diff --git a/.gitignore b/.gitignore
index 626818bb5..bbf76b856 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,7 @@
 .DS_Store
 
 node_modules
+.pnpm-store/
 dist/
 build/
 out/
diff --git a/.prettierignore b/.prettierignore
index b1e0c132d..44b32ea4a 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -2,3 +2,7 @@ build/
 out/
 
 pnpm-lock.yaml
+
+# Each live worktree is a second copy of the repo, inside it. Without this the
+# gate checks every one of them, and fails on a branch you cannot fix from here.
+.claude/worktrees/
diff --git a/jest.config.js b/jest.config.js
index 434bb33ba..e632d81c8 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -46,6 +46,12 @@ export default {
         // Stylesheet imports have no transform here; the `.js` rule above runs first, so the
         // `*.css.ts` style modules are unaffected.
         '\\.s?css$': '<rootDir>/src/__tests__/mocks/styleStub.ts',
+        // jsdom's ElementInternals has no setFormValue, so a form-associated element fails on
+        // its first update, and vscode-icon warns on every connect about the missing codicon
+        // stylesheet. Every importer wants the side effect only. vscode-single-select is the
+        // exception: VsSelect extends the class and reads its styles, so it must stay real.
+        '^#vscode-elements/(?!vscode-single-select\\.js$)':
+          '<rootDir>/src/__tests__/mocks/vscodeElementStub.ts',
       },
       transformIgnorePatterns: [
         // allow transformation of pixi.js and its dependencies
diff --git a/lana/src/__tests__/Main.test.ts b/lana/src/__tests__/Main.test.ts
index 1ef26067c..c0422f57c 100644
--- a/lana/src/__tests__/Main.test.ts
+++ b/lana/src/__tests__/Main.test.ts
@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
-import { beforeEach, describe, expect, it } from '@jest/globals';
+import { describe, expect, it } from '@jest/globals';
 
 import { createMockExtensionContext } from './mocks/vscode.js';
 import { Context } from '../Context.js';
@@ -22,10 +22,6 @@ const mockDisposeServices = disposeServices as jest.Mock;
 const mockInitServices = initServices as jest.Mock;
 
 describe('Main', () => {
-  beforeEach(() => {
-    jest.clearAllMocks();
-  });
-
   it('activates without initializing Salesforce Services', () => {
     const extensionContext = createMockExtensionContext();
 
diff --git a/lana/src/__tests__/helpers/test-builders.ts b/lana/src/__tests__/helpers/test-builders.ts
index 8ea2cce15..b8630024d 100644
--- a/lana/src/__tests__/helpers/test-builders.ts
+++ b/lana/src/__tests__/helpers/test-builders.ts
@@ -8,7 +8,13 @@
 
 import type { ApexLog, LogEvent } from 'apex-log-parser';
 
-import { createMockExtensionContext, type MockExtensionContext } from '../mocks/vscode.js';
+import type { Context } from '../../Context.js';
+
+import {
+  commands,
+  createMockExtensionContext,
+  type MockExtensionContext,
+} from '../mocks/vscode.js';
 
 /**
  * Partial type for creating mock LogEvent objects.
@@ -200,3 +206,25 @@ export function createMockContext(overrides: Partial<MockContext> = {}): MockCon
 
   return { ...base, ...overrides };
 }
+
+/**
+ * A mock where the code under test wants the real Context. The mock carries the
+ * fields a command reaches for and nothing else, so the compiler cannot see it as
+ * one without being told.
+ */
+export function asContext(mock: MockContext): Context {
+  return mock as unknown as Context;
+}
+
+/**
+ * The handler the code under test registered last. A command registers on apply,
+ * so the last call is the one the case just made. Every handler is `Command.run`,
+ * which is why one signature covers them all.
+ */
+export function lastRegisteredCommand(): (...args: unknown[]) => Promise<unknown> {
+  const handler = commands.registerCommand.mock.calls.at(-1)?.[1];
+  if (!handler) {
+    throw new Error('no command registered — did the case call apply()?');
+  }
+  return handler as (...args: unknown[]) => Promise<unknown>;
+}
diff --git a/lana/src/__tests__/log-utils.test.ts b/lana/src/__tests__/log-utils.test.ts
index e781caa78..a6e0534df 100644
--- a/lana/src/__tests__/log-utils.test.ts
+++ b/lana/src/__tests__/log-utils.test.ts
@@ -8,154 +8,55 @@ import { createMockLogEvent } from './helpers/test-builders.js';
 
 describe('log-utils', () => {
   describe('formatDuration', () => {
-    describe('milliseconds (< 1 second)', () => {
-      it('should format nanoseconds as milliseconds for small values', () => {
-        expect(formatDuration(1_000_000)).toBe('1.00ms');
-      });
-
-      it('should format sub-millisecond values', () => {
-        expect(formatDuration(500_000)).toBe('0.50ms');
-      });
-
-      it('should format zero duration', () => {
-        expect(formatDuration(0)).toBe('0.00ms');
-      });
-
-      it('should format values just under 1 second', () => {
-        expect(formatDuration(999_000_000)).toBe('999.00ms');
-      });
-
-      it('should format with 2 decimal places', () => {
-        expect(formatDuration(123_456_789)).toBe('123.46ms');
-      });
-    });
-
-    describe('seconds (1-60 seconds)', () => {
-      it('should format exactly 1 second', () => {
-        expect(formatDuration(1_000_000_000)).toBe('1.00s');
-      });
-
-      it('should format seconds with decimals', () => {
-        expect(formatDuration(1_500_000_000)).toBe('1.50s');
-      });
-
-      it('should format values just under 60 seconds', () => {
-        expect(formatDuration(59_990_000_000)).toBe('59.99s');
-      });
-
-      it('should format 30 seconds', () => {
-        expect(formatDuration(30_000_000_000)).toBe('30.00s');
-      });
+    // The unit steps at 1s and at 60s, so the rows either side of each are the ones
+    // that matter.
+    it.each([
+      [0, '0.00ms'],
+      [500_000, '0.50ms'],
+      [1_000_000, '1.00ms'],
+      [999_000_000, '999.00ms'],
+      [1_000_000_000, '1.00s'],
+      [1_500_000_000, '1.50s'],
+      [30_000_000_000, '30.00s'],
+      [59_990_000_000, '59.99s'],
+      [60_000_000_000, '1m 0.00s'],
+      [90_000_000_000, '1m 30.00s'],
+      [150_000_000_000, '2m 30.00s'],
+      [600_000_000_000, '10m 0.00s'],
+    ])('formats %d ns as %s', (ns, expected) => {
+      expect(formatDuration(ns)).toBe(expected);
     });
 
-    describe('minutes (>= 60 seconds)', () => {
-      it('should format exactly 1 minute', () => {
-        expect(formatDuration(60_000_000_000)).toBe('1m 0.00s');
-      });
-
-      it('should format 1 minute and 30 seconds', () => {
-        expect(formatDuration(90_000_000_000)).toBe('1m 30.00s');
-      });
-
-      it('should format multiple minutes', () => {
-        expect(formatDuration(150_000_000_000)).toBe('2m 30.00s');
-      });
-
-      it('should format large duration', () => {
-        expect(formatDuration(600_000_000_000)).toBe('10m 0.00s');
-      });
-
-      it('should format minutes with fractional seconds', () => {
-        expect(formatDuration(61_234_567_890)).toBe('1m 1.23s');
-      });
+    it.each([
+      [123_456_789, '123.46ms'],
+      [61_234_567_890, '1m 1.23s'],
+    ])('rounds %d ns to two decimal places, giving %s', (ns, expected) => {
+      expect(formatDuration(ns)).toBe(expected);
     });
   });
 
   describe('TIMESTAMP_REGEX', () => {
-    describe('valid timestamps', () => {
-      it('should match standard timestamp format', () => {
-        const line = '09:45:31.888 (38889007737)|METHOD_ENTRY';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).not.toBeNull();
-        expect(match?.[1]).toBe('38889007737');
-      });
-
-      it('should match timestamp at start of log line', () => {
-        const line = '12:00:00.000 (1000)|CODE_UNIT_STARTED';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).not.toBeNull();
-        expect(match?.[1]).toBe('1000');
-      });
-
-      it('should match timestamp with long nanoseconds', () => {
-        const line = '23:59:59.999 (999999999999)|SOQL_EXECUTE_BEGIN';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).not.toBeNull();
-        expect(match?.[1]).toBe('999999999999');
-      });
-
-      it('should match timestamp with short nanoseconds', () => {
-        const line = '00:00:00.001 (1)|DML_BEGIN';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).not.toBeNull();
-        expect(match?.[1]).toBe('1');
-      });
-
-      it('should match timestamp with varying decimal precision', () => {
-        const line = '10:30:45.1 (12345)|EXECUTION_STARTED';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).not.toBeNull();
-        expect(match?.[1]).toBe('12345');
-      });
-
-      it('should match timestamp with space before parentheses', () => {
-        const line = '09:45:31.888 (38889007737)|METHOD_ENTRY';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).not.toBeNull();
-      });
+    it.each([
+      ['09:45:31.888 (38889007737)|METHOD_ENTRY', '38889007737'],
+      ['12:00:00.000 (1000)|CODE_UNIT_STARTED', '1000'],
+      ['23:59:59.999 (999999999999)|SOQL_EXECUTE_BEGIN', '999999999999'],
+      ['00:00:00.001 (1)|DML_BEGIN', '1'],
+      // One decimal place, not three.
+      ['10:30:45.1 (12345)|EXECUTION_STARTED', '12345'],
+    ])('captures the nanoseconds of %s', (line, expected) => {
+      expect(line.match(TIMESTAMP_REGEX)?.[1]).toBe(expected);
     });
 
-    describe('invalid timestamps', () => {
-      it('should not match line without timestamp', () => {
-        const line = 'This is just some text';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).toBeNull();
-      });
-
-      it('should not match malformed time', () => {
-        const line = '9:45:31.888 (38889007737)|METHOD_ENTRY';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).toBeNull();
-      });
-
-      it('should not match timestamp without pipe', () => {
-        const line = '09:45:31.888 (38889007737) METHOD_ENTRY';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).toBeNull();
-      });
-
-      it('should not match timestamp in middle of line', () => {
-        const line = 'prefix 09:45:31.888 (38889007737)|METHOD_ENTRY';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).toBeNull();
-      });
-
-      it('should not match empty string', () => {
-        const line = '';
-        const match = line.match(TIMESTAMP_REGEX);
-
-        expect(match).toBeNull();
-      });
+    it.each([
+      'This is just some text',
+      // A single-digit hour.
+      '9:45:31.888 (38889007737)|METHOD_ENTRY',
+      '09:45:31.888 (38889007737) METHOD_ENTRY',
+      // Anchored, so a timestamp that does not start the line is not one.
+      'prefix 09:45:31.888 (38889007737)|METHOD_ENTRY',
+      '',
+    ])('does not match %p', (line) => {
+      expect(line.match(TIMESTAMP_REGEX)).toBeNull();
     });
   });
 
diff --git a/lana/src/cache/__tests__/LogEventCache.test.ts b/lana/src/cache/__tests__/LogEventCache.test.ts
index 3d569fe35..480f66420 100644
--- a/lana/src/cache/__tests__/LogEventCache.test.ts
+++ b/lana/src/cache/__tests__/LogEventCache.test.ts
@@ -6,6 +6,7 @@ import { Uri, workspace } from 'vscode';
 
 import {
   createMockApexLog,
+  asContext,
   createMockContext,
   createMockDisplay,
   createMockLogEvent,
@@ -396,7 +397,7 @@ describe('LogEventCache', () => {
     it('should register onDidCloseTextDocument listener', () => {
       const mockContext = createMockContext();
 
-      LogEventCache.apply(mockContext as unknown as import('../../Context.js').Context);
+      LogEventCache.apply(asContext(mockContext));
 
       expect(workspace.onDidCloseTextDocument).toHaveBeenCalledTimes(1);
       expect(mockContext.context.subscriptions.length).toBe(1);
@@ -418,7 +419,7 @@ describe('LogEventCache', () => {
       });
 
       const mockContext = createMockContext();
-      LogEventCache.apply(mockContext as unknown as import('../../Context.js').Context);
+      LogEventCache.apply(asContext(mockContext));
 
       // Simulate closing an apexlog document
       closeCallback!({
@@ -446,7 +447,7 @@ describe('LogEventCache', () => {
       });
 
       const mockContext = createMockContext();
-      LogEventCache.apply(mockContext as unknown as import('../../Context.js').Context);
+      LogEventCache.apply(asContext(mockContext));
 
       // A log saved as .trace or pasted into an untitled buffer never gets the apexlog
       // language, but the decoration provider still parses it, so it must still clear.
diff --git a/lana/src/commands/__tests__/Command.test.ts b/lana/src/commands/__tests__/Command.test.ts
index 41263160d..292ee3c41 100644
--- a/lana/src/commands/__tests__/Command.test.ts
+++ b/lana/src/commands/__tests__/Command.test.ts
@@ -1,26 +1,21 @@
 /*
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
-import { beforeEach, describe, expect, it } from '@jest/globals';
+import { describe, expect, it } from '@jest/globals';
 import { commands } from 'vscode';
 
-import type { Context } from '../../Context.js';
-import { createMockContext } from '../../__tests__/helpers/test-builders.js';
+import { asContext, createMockContext } from '../../__tests__/helpers/test-builders.js';
 import { Command } from '../Command.js';
 
 const mockRegisterCommand = commands.registerCommand as jest.Mock;
 
 describe('Command', () => {
-  beforeEach(() => {
-    jest.clearAllMocks();
-  });
-
   it('returns what the handler returns', async () => {
     const context = createMockContext();
     const command = new Command(
       'aCommand',
       'A Command',
-      context as unknown as Context,
+      asContext(context),
       'Error running the command',
       () => Promise.resolve('a result'),
     );
@@ -34,7 +29,7 @@ describe('Command', () => {
     const command = new Command(
       'aCommand',
       'A Command',
-      context as unknown as Context,
+      asContext(context),
       'Error running the command',
       () => Promise.reject(new Error('it broke')),
     );
@@ -50,7 +45,7 @@ describe('Command', () => {
     const command = new Command(
       'aCommand',
       'A Command',
-      context as unknown as Context,
+      asContext(context),
       'Error running the command',
       () => {
         throw new Error('it broke');
@@ -65,12 +60,8 @@ describe('Command', () => {
 
   it('registers the guarded handler, not the raw one', async () => {
     const context = createMockContext();
-    new Command(
-      'aCommand',
-      'A Command',
-      context as unknown as Context,
-      'Error running the command',
-      () => Promise.reject(new Error('it broke')),
+    new Command('aCommand', 'A Command', asContext(context), 'Error running the command', () =>
+      Promise.reject(new Error('it broke')),
     ).register();
 
     const [name, registered] = mockRegisterCommand.mock.calls[0] as [
diff --git a/lana/src/commands/__tests__/LogView.test.ts b/lana/src/commands/__tests__/LogView.test.ts
index 1afb75652..934870fc8 100644
--- a/lana/src/commands/__tests__/LogView.test.ts
+++ b/lana/src/commands/__tests__/LogView.test.ts
@@ -3,7 +3,7 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-import { createMockContext } from '../../__tests__/helpers/test-builders.js';
+import { asContext, createMockContext } from '../../__tests__/helpers/test-builders.js';
 import { Uri, workspace } from '../../__tests__/mocks/vscode.js';
 import { getConfig } from '../../workspace/AppConfig.js';
 import { WebView } from '../../display/WebView.js';
@@ -75,7 +75,7 @@ describe('LogView', () => {
     );
 
     await LogView.createView(
-      createMockContext() as unknown as import('../../Context.js').Context,
+      asContext(createMockContext()),
       Promise.resolve(),
       Uri.parse('memfs:/repository/logs/virtual.log'),
       'log body',
@@ -109,12 +109,7 @@ describe('LogView', () => {
     const context = createMockContext();
     const logUri = Uri.parse('memfs:/repository/logs/virtual.log');
 
-    await LogView.createView(
-      context as unknown as import('../../Context.js').Context,
-      Promise.resolve(),
-      logUri,
-      'log body',
-    );
+    await LogView.createView(asContext(context), Promise.resolve(), logUri, 'log body');
     // createView must resolve and rewrite the bundled index.html. It read that
     // file through a service needing another extension's initialisation, so it
     // rejected before the webview had any content.
@@ -147,7 +142,7 @@ describe('LogView', () => {
       new TextEncoder().encode('<script src="bundle.js"></script><link href="codicon.css">'),
     );
 
-    await LogView.createView(createMockContext() as unknown as import('../../Context.js').Context);
+    await LogView.createView(asContext(createMockContext()));
 
     expect(mockReadFile).toHaveBeenCalledWith(Uri.parse('file:///test/extension/out/index.html'));
     expect(panel.webview.html).toContain('webview:/test/extension/out/bundle.js');
@@ -166,7 +161,7 @@ describe('LogView', () => {
     try {
       const context = createMockContext();
       const failed = Promise.reject(new Error('org unreachable'));
-      await LogView.createView(context as unknown as import('../../Context.js').Context, failed);
+      await LogView.createView(asContext(context), failed);
       // No fetchLog is posted, so nothing here awaits the body.
       await new Promise((resolve) => setImmediate(resolve));
       expect(unhandled).toEqual([]);
@@ -185,9 +180,9 @@ describe('LogView', () => {
     mockApplyWebView.mockReturnValue(panel as unknown as import('vscode').WebviewPanel);
     mockReadFile.mockRejectedValue(new Error('ENOENT'));
 
-    await expect(
-      LogView.createView(createMockContext() as unknown as import('../../Context.js').Context),
-    ).rejects.toThrow('Could not read the log viewer at /test/extension/out/index.html: ENOENT');
+    await expect(LogView.createView(asContext(createMockContext()))).rejects.toThrow(
+      'Could not read the log viewer at /test/extension/out/index.html: ENOENT',
+    );
   });
 
   it('answers a request whose case throws, so the webview stops waiting', async () => {
diff --git a/lana/src/commands/__tests__/RetrieveLogFile.test.ts b/lana/src/commands/__tests__/RetrieveLogFile.test.ts
index bd89fec92..3e0fd9057 100644
--- a/lana/src/commands/__tests__/RetrieveLogFile.test.ts
+++ b/lana/src/commands/__tests__/RetrieveLogFile.test.ts
@@ -2,8 +2,12 @@
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
 import { beforeEach, describe, expect, it } from '@jest/globals';
-import { commands, Uri, window, workspace } from 'vscode';
-import { createMockContext } from '../../__tests__/helpers/test-builders.js';
+import { Uri, window, workspace } from 'vscode';
+import {
+  asContext,
+  createMockContext,
+  lastRegisteredCommand,
+} from '../../__tests__/helpers/test-builders.js';
 import { QuickPick } from '../../display/QuickPick.js';
 import {
   ensureServicesAvailable,
@@ -56,7 +60,6 @@ const mockListLogs = listLogs as jest.Mock;
 const mockGetLogBody = getLogBody as jest.Mock;
 const mockWriteFile = writeFile as jest.Mock;
 const mockCreateView = LogView.createView as jest.Mock;
-const mockRegisterCommand = commands.registerCommand as jest.Mock;
 const mockWorkspace = workspace as unknown as {
   workspaceFolders: Array<{
     uri: ReturnType<typeof Uri.file>;
@@ -82,7 +85,6 @@ function retrieveLogPromise(): Promise<string | void> {
 
 describe('RetrieveLogFile', () => {
   beforeEach(() => {
-    jest.clearAllMocks();
     mockEnsureServicesAvailable.mockResolvedValue(true);
     mockFileOrFolderExists.mockResolvedValue(false);
     mockWorkspace.workspaceFolders = [
@@ -114,13 +116,12 @@ describe('RetrieveLogFile', () => {
 
   const settle = () => new Promise((resolve) => setImmediate(resolve));
 
-  const command = (): (() => Promise<unknown>) =>
-    mockRegisterCommand.mock.calls[mockRegisterCommand.mock.calls.length - 1]?.[1];
+  const command = () => lastRegisteredCommand();
 
   it('closes the loading picker and says so when Salesforce cannot list the logs', async () => {
     mockListLogs.mockRejectedValue(new Error('no org connection'));
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
 
     await command()();
 
@@ -133,7 +134,7 @@ describe('RetrieveLogFile', () => {
   it('cancels the log list when the user dismisses the picker', async () => {
     mockListLogs.mockReturnValue(new Promise(() => {}));
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
 
     const running = command()();
     await settle();
@@ -149,7 +150,7 @@ describe('RetrieveLogFile', () => {
   it('closes the loading picker and reports nothing when the user dismisses it', async () => {
     mockListLogs.mockReturnValue(new Promise(() => {}));
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
 
     const running = command()();
     await settle();
@@ -163,13 +164,13 @@ describe('RetrieveLogFile', () => {
 
   it('registers the command', () => {
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
     expect(context.context.subscriptions).toHaveLength(1);
   });
 
   it('lists logs through Salesforce Services', async () => {
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
     await command()();
     expect(mockEnsureServicesAvailable).toHaveBeenCalledWith();
     expect(mockListLogs).toHaveBeenCalledWith(expect.any(AbortSignal));
@@ -179,7 +180,7 @@ describe('RetrieveLogFile', () => {
     mockListLogs.mockResolvedValue([log('selected-log')]);
     mockPick.mockResolvedValue([{ logId: 'selected-log' }]);
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
     await command()();
 
     expect(mockCreateView).toHaveBeenCalledWith(
@@ -207,7 +208,7 @@ describe('RetrieveLogFile', () => {
     mockListLogs.mockResolvedValue([log('selected-log')]);
     mockPick.mockResolvedValue([{ logId: 'selected-log' }]);
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
 
     await command()();
 
@@ -226,7 +227,7 @@ describe('RetrieveLogFile', () => {
     mockPick.mockResolvedValue([{ logId: 'cached-log' }]);
     mockFileOrFolderExists.mockResolvedValue(true);
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
     await command()();
 
     expect(mockGetLogBody).not.toHaveBeenCalled();
@@ -242,7 +243,7 @@ describe('RetrieveLogFile', () => {
     mockEnsureServicesAvailable.mockResolvedValue(false);
     mockWorkspace.workspaceFolders = [];
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
     await command()();
 
     expect(mockListLogs).not.toHaveBeenCalled();
@@ -254,7 +255,7 @@ describe('RetrieveLogFile', () => {
     mockPick.mockResolvedValue([{ logId: 'selected-log' }]);
     mockWriteFile.mockRejectedValue(new Error('read-only workspace'));
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
     await command()();
 
     expect(mockCreateView).toHaveBeenCalled();
@@ -276,7 +277,7 @@ describe('RetrieveLogFile', () => {
       return Promise.resolve([]);
     });
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
     await command()();
     expect(items.map((item) => item.logId)).toEqual(['new', 'old']);
   });
@@ -299,7 +300,7 @@ describe('RetrieveLogFile', () => {
       return Promise.resolve([]);
     });
     const context = createMockContext();
-    RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+    RetrieveLogFile.apply(asContext(context));
     await command()();
     expect(description).toContain(expectedDuration);
   });
@@ -311,7 +312,7 @@ describe('RetrieveLogFile', () => {
       mockPick.mockResolvedValue([{ logId: 'denied' }]);
       mockGetLogBody.mockResolvedValue(response);
       const context = createMockContext();
-      RetrieveLogFile.apply(context as unknown as import('../../Context.js').Context);
+      RetrieveLogFile.apply(asContext(context));
       await command()();
       await expect(retrieveLogPromise()).rejects.toThrow('Salesforce denied access');
     },
diff --git a/lana/src/commands/__tests__/ShowInLogAnalysis.test.ts b/lana/src/commands/__tests__/ShowInLogAnalysis.test.ts
index 8f1037947..993567a28 100644
--- a/lana/src/commands/__tests__/ShowInLogAnalysis.test.ts
+++ b/lana/src/commands/__tests__/ShowInLogAnalysis.test.ts
@@ -2,10 +2,12 @@
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
 import { beforeEach, describe, expect, it } from '@jest/globals';
-import { commands } from 'vscode';
 
-import type { Context } from '../../Context.js';
-import { createMockContext } from '../../__tests__/helpers/test-builders.js';
+import {
+  asContext,
+  createMockContext,
+  lastRegisteredCommand,
+} from '../../__tests__/helpers/test-builders.js';
 import { LogView } from '../LogView.js';
 import { ShowInLogAnalysis } from '../ShowInLogAnalysis.js';
 
@@ -20,21 +22,18 @@ jest.mock('../LogView.js', () => ({
 
 const mockCreateView = LogView.createView as jest.Mock;
 const mockGetCurrentView = LogView.getCurrentView as jest.Mock;
-const mockRegisterCommand = commands.registerCommand as jest.Mock;
 
 describe('ShowInLogAnalysis', () => {
   beforeEach(() => {
-    jest.clearAllMocks();
     mockGetCurrentView.mockReturnValue(undefined);
     mockCreateView.mockResolvedValue(undefined);
   });
 
-  const command = (): ((args: unknown) => Promise<unknown>) =>
-    mockRegisterCommand.mock.calls[mockRegisterCommand.mock.calls.length - 1]?.[1];
+  const command = () => lastRegisteredCommand();
 
   it('opens the log at the timestamp', async () => {
     const context = createMockContext();
-    ShowInLogAnalysis.apply(context as unknown as Context);
+    ShowInLogAnalysis.apply(asContext(context));
 
     await command()({ timestamp: 42, filePath: 'memfs:/logs/a.log' });
 
@@ -46,7 +45,7 @@ describe('ShowInLogAnalysis', () => {
   it('reports a failure to open the log rather than failing silently', async () => {
     mockCreateView.mockRejectedValue(new Error('viewer is missing'));
     const context = createMockContext();
-    ShowInLogAnalysis.apply(context as unknown as Context);
+    ShowInLogAnalysis.apply(asContext(context));
 
     await expect(
       command()({ timestamp: 42, filePath: 'memfs:/logs/a.log' }),
diff --git a/lana/src/commands/__tests__/ShowLogAnalysis.test.ts b/lana/src/commands/__tests__/ShowLogAnalysis.test.ts
index 55aeb13f8..aa1820234 100644
--- a/lana/src/commands/__tests__/ShowLogAnalysis.test.ts
+++ b/lana/src/commands/__tests__/ShowLogAnalysis.test.ts
@@ -2,9 +2,13 @@
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
 import { beforeEach, describe, expect, it } from '@jest/globals';
-import { commands, Uri } from 'vscode';
+import { Uri } from 'vscode';
 
-import { createMockContext } from '../../__tests__/helpers/test-builders.js';
+import {
+  asContext,
+  createMockContext,
+  lastRegisteredCommand,
+} from '../../__tests__/helpers/test-builders.js';
 import { fileOrFolderExists } from '../../fs/workspaceFs.js';
 import { LogView } from '../LogView.js';
 import { ShowLogAnalysis } from '../ShowLogAnalysis.js';
@@ -14,21 +18,18 @@ jest.mock('../LogView.js', () => ({ LogView: { createView: jest.fn() } }));
 
 const mockFileOrFolderExists = fileOrFolderExists as jest.Mock;
 const mockCreateView = LogView.createView as jest.Mock;
-const mockRegisterCommand = commands.registerCommand as jest.Mock;
 
 describe('ShowLogAnalysis', () => {
   beforeEach(() => {
-    jest.clearAllMocks();
     mockFileOrFolderExists.mockResolvedValue(true);
     mockCreateView.mockResolvedValue(undefined);
   });
 
-  const command = (): ((uri: unknown) => Promise<unknown>) =>
-    mockRegisterCommand.mock.calls[mockRegisterCommand.mock.calls.length - 1]?.[1];
+  const command = () => lastRegisteredCommand();
 
   it('opens the log passed to it', async () => {
     const context = createMockContext();
-    ShowLogAnalysis.apply(context as unknown as import('../../Context.js').Context);
+    ShowLogAnalysis.apply(asContext(context));
 
     await command()(Uri.parse('memfs:/logs/a.log'));
 
@@ -39,7 +40,7 @@ describe('ShowLogAnalysis', () => {
   it('reports a failure to open the log rather than failing silently', async () => {
     mockCreateView.mockRejectedValue(new Error('viewer is missing'));
     const context = createMockContext();
-    ShowLogAnalysis.apply(context as unknown as import('../../Context.js').Context);
+    ShowLogAnalysis.apply(asContext(context));
 
     await expect(command()(Uri.parse('memfs:/logs/a.log'))).resolves.toBeUndefined();
 
diff --git a/lana/src/commands/__tests__/SwitchTimelineTheme.test.ts b/lana/src/commands/__tests__/SwitchTimelineTheme.test.ts
index a4733b238..e4845cfb2 100644
--- a/lana/src/commands/__tests__/SwitchTimelineTheme.test.ts
+++ b/lana/src/commands/__tests__/SwitchTimelineTheme.test.ts
@@ -5,7 +5,7 @@ import { beforeEach, describe, expect, it } from '@jest/globals';
 
 import { Uri, window } from 'vscode';
 
-import { createMockContext } from '../../__tests__/helpers/test-builders.js';
+import { asContext, createMockContext } from '../../__tests__/helpers/test-builders.js';
 import { SwitchTimelineTheme } from '../SwitchTimelineTheme.js';
 
 // Mock AppConfig
@@ -82,18 +82,14 @@ describe('SwitchTimelineTheme', () => {
   describe('getCommand', () => {
     it('should return command with correct name', () => {
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       expect(command.name).toBe('switchTimelineTheme');
     });
 
     it('should return command with correct title', () => {
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       expect(command.title).toBe('Log: Timeline Theme');
     });
@@ -103,9 +99,7 @@ describe('SwitchTimelineTheme', () => {
         throw new Error('config unavailable');
       });
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await expect(command.run(Uri.parse('memfs:/logs/a.log'))).resolves.toBeUndefined();
 
@@ -118,9 +112,7 @@ describe('SwitchTimelineTheme', () => {
   describe('theme list building', () => {
     it('should include all preset themes', async () => {
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -143,9 +135,7 @@ describe('SwitchTimelineTheme', () => {
       });
 
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -170,9 +160,7 @@ describe('SwitchTimelineTheme', () => {
       });
 
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -183,9 +171,7 @@ describe('SwitchTimelineTheme', () => {
 
     it('should mark default theme with description', async () => {
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -195,9 +181,7 @@ describe('SwitchTimelineTheme', () => {
 
     it('should not mark non-default built-in themes as custom', async () => {
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -216,9 +200,7 @@ describe('SwitchTimelineTheme', () => {
       });
 
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -237,9 +219,7 @@ describe('SwitchTimelineTheme', () => {
       });
 
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -255,9 +235,7 @@ describe('SwitchTimelineTheme', () => {
       });
 
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -274,9 +252,7 @@ describe('SwitchTimelineTheme', () => {
       mockGetCurrentView.mockReturnValue({ webview: mockWebview });
 
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -293,9 +269,7 @@ describe('SwitchTimelineTheme', () => {
       mockGetCurrentView.mockReturnValue(null);
 
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -308,9 +282,7 @@ describe('SwitchTimelineTheme', () => {
   describe('theme selection', () => {
     it('should update config on accept', async () => {
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -324,9 +296,7 @@ describe('SwitchTimelineTheme', () => {
 
     it('should hide picker on accept', async () => {
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -340,9 +310,7 @@ describe('SwitchTimelineTheme', () => {
     it('reports a failure to save the chosen theme', async () => {
       mockUpdateConfig.mockRejectedValue(new Error('settings are read-only'));
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -371,9 +339,7 @@ describe('SwitchTimelineTheme', () => {
       });
 
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -391,9 +357,7 @@ describe('SwitchTimelineTheme', () => {
 
     it('should dispose picker on hide', async () => {
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
       onDidHideCallback();
@@ -415,9 +379,7 @@ describe('SwitchTimelineTheme', () => {
       });
 
       const mockContext = createMockContext();
-      const command = SwitchTimelineTheme.getCommand(
-        mockContext as unknown as import('../../Context.js').Context,
-      );
+      const command = SwitchTimelineTheme.getCommand(asContext(mockContext));
 
       await command.run({} as never);
 
@@ -437,7 +399,7 @@ describe('SwitchTimelineTheme', () => {
     it('should register command with context', () => {
       const mockContext = createMockContext();
 
-      SwitchTimelineTheme.apply(mockContext as unknown as import('../../Context.js').Context);
+      SwitchTimelineTheme.apply(asContext(mockContext));
 
       expect(mockContext.context.subscriptions.length).toBe(1);
     });
@@ -445,7 +407,7 @@ describe('SwitchTimelineTheme', () => {
     it('should output registration message', () => {
       const mockContext = createMockContext();
 
-      SwitchTimelineTheme.apply(mockContext as unknown as import('../../Context.js').Context);
+      SwitchTimelineTheme.apply(asContext(mockContext));
 
       expect(mockContext.display.output).toHaveBeenCalledWith(
         "Registered command 'Lana: Timeline Theme'",
diff --git a/lana/src/decorations/__tests__/RawLogLineDecoration.test.ts b/lana/src/decorations/__tests__/RawLogLineDecoration.test.ts
index 4d82492ae..1748c4cba 100644
--- a/lana/src/decorations/__tests__/RawLogLineDecoration.test.ts
+++ b/lana/src/decorations/__tests__/RawLogLineDecoration.test.ts
@@ -7,6 +7,7 @@ import { window, type TextDocument, type TextEditor } from 'vscode';
 
 import {
   createMockApexLog,
+  asContext,
   createMockContext,
   createMockLogEvent,
 } from '../../__tests__/helpers/test-builders.js';
@@ -19,7 +20,6 @@ import {
   setOpenTabs,
 } from '../../__tests__/mocks/vscode.js';
 import { LogEventCache } from '../../cache/LogEventCache.js';
-import type { Context } from '../../Context.js';
 import { RawLogLineDecoration } from '../RawLogLineDecoration.js';
 
 jest.mock('../../cache/LogEventCache.js', () => ({
@@ -60,13 +60,12 @@ describe('RawLogLineDecoration', () => {
   let mockContext: ReturnType<typeof createMockContext>;
 
   beforeEach(() => {
-    jest.clearAllMocks();
     jest.useFakeTimers();
     // The class keeps one instance for the life of the extension host.
     (RawLogLineDecoration as unknown as { instance: unknown }).instance = null;
     setOpenTabs(new TabInputText(Uri.file(LOG_URI)));
     mockContext = createMockContext();
-    RawLogLineDecoration.apply(mockContext as unknown as Context);
+    RawLogLineDecoration.apply(asContext(mockContext));
   });
 
   afterEach(() => {
@@ -79,8 +78,8 @@ describe('RawLogLineDecoration', () => {
     });
 
     it('registers once, however many times it is applied', () => {
-      RawLogLineDecoration.apply(mockContext as unknown as Context);
-      RawLogLineDecoration.apply(mockContext as unknown as Context);
+      RawLogLineDecoration.apply(asContext(mockContext));
+      RawLogLineDecoration.apply(asContext(mockContext));
 
       expect(mockOnSelectionChange).toHaveBeenCalledTimes(1);
     });
diff --git a/lana/src/display/__tests__/OpenFileInPackage.test.ts b/lana/src/display/__tests__/OpenFileInPackage.test.ts
index 6a0aa871e..f0a4c660f 100644
--- a/lana/src/display/__tests__/OpenFileInPackage.test.ts
+++ b/lana/src/display/__tests__/OpenFileInPackage.test.ts
@@ -2,7 +2,7 @@
  * Copyright (c) 2025 Certinia Inc. All rights reserved.
  */
 import { workspace } from 'vscode';
-import type { Context } from '../../Context';
+import { asContext, createMockContext } from '../../__tests__/helpers/test-builders.js';
 import { getMethodLine, parseApex } from '../../salesforce/ApexParser/ApexSymbolLocator';
 import { OpenFileInPackage } from '../OpenFileInPackage';
 
@@ -15,20 +15,13 @@ const mockGetMethodLine = getMethodLine as jest.Mock;
 const mockOpenTextDocument = workspace.openTextDocument as jest.Mock;
 
 function createContext() {
-  const workspaceManager = {
-    findSymbol: jest.fn(),
-  };
-  const display = {
-    showErrorMessage: jest.fn(),
-    showFile: jest.fn(),
-  };
-  const context = { workspaceManager, display } as unknown as Context;
-  return { context, workspaceManager, display };
+  const workspaceManager = { findSymbol: jest.fn() };
+  const mock = createMockContext({ workspaceManager });
+  return { context: asContext(mock), workspaceManager, display: mock.display };
 }
 
 describe('OpenFileInPackage.openFileForSymbol', () => {
   beforeEach(() => {
-    jest.clearAllMocks();
     mockParseApex.mockReturnValue({ name: 'myclass', children: [] });
     mockOpenTextDocument.mockResolvedValue({ getText: () => 'public class MyClass {}' });
   });
diff --git a/lana/src/display/__tests__/WhatsNewNotification.test.ts b/lana/src/display/__tests__/WhatsNewNotification.test.ts
index 9b122a4c4..f58970214 100644
--- a/lana/src/display/__tests__/WhatsNewNotification.test.ts
+++ b/lana/src/display/__tests__/WhatsNewNotification.test.ts
@@ -5,8 +5,7 @@ import { beforeEach, describe, expect, it } from '@jest/globals';
 
 import { commands, window } from 'vscode';
 
-import { createMockContext } from '../../__tests__/helpers/test-builders.js';
-import type { Context } from '../../Context.js';
+import { asContext, createMockContext } from '../../__tests__/helpers/test-builders.js';
 import { WhatsNewNotification } from '../WhatsNewNotification.js';
 
 const mockShowInformationMessage = window.showInformationMessage as jest.Mock;
@@ -22,12 +21,8 @@ function contextForVersion(version: string, viewed: string[] = []) {
   return mockContext;
 }
 
-const asContext = (mockContext: ReturnType<typeof createMockContext>) =>
-  mockContext as unknown as Context;
-
 describe('WhatsNewNotification', () => {
   beforeEach(() => {
-    jest.clearAllMocks();
     mockShowInformationMessage.mockResolvedValue(undefined);
   });
 
diff --git a/lana/src/folding/__tests__/RawLogFoldingProvider.test.ts b/lana/src/folding/__tests__/RawLogFoldingProvider.test.ts
index 8758a7fd8..a9569f06d 100644
--- a/lana/src/folding/__tests__/RawLogFoldingProvider.test.ts
+++ b/lana/src/folding/__tests__/RawLogFoldingProvider.test.ts
@@ -8,6 +8,7 @@ import { FoldingRangeKind, languages, window, workspace } from 'vscode';
 import {
   createMockDisplay,
   createMockApexLog,
+  asContext,
   createMockContext,
   createMockLogEvent,
 } from '../../__tests__/helpers/test-builders.js';
@@ -316,7 +317,7 @@ describe('RawLogFoldingProvider', () => {
     it('should register folding range provider for apexlog', () => {
       const mockContext = createMockContext();
 
-      RawLogFoldingProvider.apply(mockContext as unknown as import('../../Context.js').Context);
+      RawLogFoldingProvider.apply(asContext(mockContext));
 
       expect(languages.registerFoldingRangeProvider).toHaveBeenCalledTimes(1);
       expect(languages.registerFoldingRangeProvider).toHaveBeenCalledWith(
@@ -328,7 +329,7 @@ describe('RawLogFoldingProvider', () => {
     it('warms on tab changes, not on document open', () => {
       const mockContext = createMockContext();
 
-      RawLogFoldingProvider.apply(mockContext as unknown as import('../../Context.js').Context);
+      RawLogFoldingProvider.apply(asContext(mockContext));
 
       // onDidOpenTextDocument fires before the tab model updates, so isOpenAsTextTab
       // would reject a legitimate open.
@@ -339,7 +340,7 @@ describe('RawLogFoldingProvider', () => {
     it('should add disposables to context subscriptions', () => {
       const mockContext = createMockContext();
 
-      RawLogFoldingProvider.apply(mockContext as unknown as import('../../Context.js').Context);
+      RawLogFoldingProvider.apply(asContext(mockContext));
 
       // emitter + folding provider registration + tab listener + active-editor listener
       expect(mockContext.context.subscriptions.length).toBe(4);
@@ -352,7 +353,7 @@ describe('RawLogFoldingProvider', () => {
 
     function applyAndCapture() {
       const mockContext = createMockContext();
-      RawLogFoldingProvider.apply(mockContext as unknown as import('../../Context.js').Context);
+      RawLogFoldingProvider.apply(asContext(mockContext));
 
       const registeredProvider = (languages.registerFoldingRangeProvider as jest.Mock).mock
         .calls[0]?.[1] as RawLogFoldingProvider;
diff --git a/lana/src/language/__tests__/ApexLogLanguageDetector.test.ts b/lana/src/language/__tests__/ApexLogLanguageDetector.test.ts
index 4b4f8a506..98da3db04 100644
--- a/lana/src/language/__tests__/ApexLogLanguageDetector.test.ts
+++ b/lana/src/language/__tests__/ApexLogLanguageDetector.test.ts
@@ -3,7 +3,7 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-import { createMockContext } from '../../__tests__/helpers/test-builders.js';
+import { asContext, createMockContext } from '../../__tests__/helpers/test-builders.js';
 import { createMockTextDocument } from '../../__tests__/mocks/vscode.js';
 import {
   TabInputText,
@@ -115,9 +115,7 @@ describe('ApexLogLanguageDetector', () => {
     });
     workspace.textDocuments = [doc];
 
-    ApexLogLanguageDetector.apply(
-      createMockContext() as unknown as import('../../Context.js').Context,
-    );
+    ApexLogLanguageDetector.apply(asContext(createMockContext()));
 
     expect(languages.setTextDocumentLanguage).toHaveBeenCalledWith(doc, 'apexlog');
   });
@@ -130,9 +128,7 @@ describe('ApexLogLanguageDetector', () => {
     Object.defineProperty(doc, 'uri', { value: Uri.parse('git:/repository/logs/virtual.json') });
     workspace.textDocuments = [doc];
 
-    ApexLogLanguageDetector.apply(
-      createMockContext() as unknown as import('../../Context.js').Context,
-    );
+    ApexLogLanguageDetector.apply(asContext(createMockContext()));
 
     expect(languages.setTextDocumentLanguage).not.toHaveBeenCalled();
   });
@@ -142,9 +138,7 @@ describe('ApexLogLanguageDetector', () => {
       input: new TabInputText(Uri.parse('memfs:/logs/huge.log')),
     };
 
-    ApexLogLanguageDetector.apply(
-      createMockContext() as unknown as import('../../Context.js').Context,
-    );
+    ApexLogLanguageDetector.apply(asContext(createMockContext()));
 
     expect(commands.executeCommand).toHaveBeenLastCalledWith('setContext', 'lana.isApexLog', true);
   });
@@ -154,9 +148,7 @@ describe('ApexLogLanguageDetector', () => {
       input: new TabInputText(Uri.parse('memfs:/logs/huge.log')),
     };
 
-    ApexLogLanguageDetector.apply(
-      createMockContext() as unknown as import('../../Context.js').Context,
-    );
+    ApexLogLanguageDetector.apply(asContext(createMockContext()));
 
     expect(workspace.fs.readFile).not.toHaveBeenCalled();
   });
@@ -166,9 +158,7 @@ describe('ApexLogLanguageDetector', () => {
       input: new TabInputText(Uri.parse('memfs:/notes.json')),
     };
 
-    ApexLogLanguageDetector.apply(
-      createMockContext() as unknown as import('../../Context.js').Context,
-    );
+    ApexLogLanguageDetector.apply(asContext(createMockContext()));
 
     expect(commands.executeCommand).toHaveBeenLastCalledWith('setContext', 'lana.isApexLog', false);
   });
@@ -176,9 +166,7 @@ describe('ApexLogLanguageDetector', () => {
   it('clears the key when the active tab is not a text tab', () => {
     window.tabGroups.activeTabGroup.activeTab = { input: {} };
 
-    ApexLogLanguageDetector.apply(
-      createMockContext() as unknown as import('../../Context.js').Context,
-    );
+    ApexLogLanguageDetector.apply(asContext(createMockContext()));
 
     expect(commands.executeCommand).toHaveBeenLastCalledWith('setContext', 'lana.isApexLog', false);
   });
diff --git a/lana/src/salesforce/__tests__/ApexVisitor.test.ts b/lana/src/salesforce/__tests__/ApexVisitor.test.ts
index bd7f67648..1a59e1e15 100644
--- a/lana/src/salesforce/__tests__/ApexVisitor.test.ts
+++ b/lana/src/salesforce/__tests__/ApexVisitor.test.ts
@@ -360,12 +360,8 @@ describe('ApexVisitor', () => {
   });
 
   describe('visit', () => {
-    it('should return empty object when ctx is null', () => {
-      expect(visitor.visit(asVisitCtx(null))).toEqual({});
-    });
-
-    it('should return empty object when ctx is undefined', () => {
-      expect(visitor.visit(asVisitCtx(undefined))).toEqual({});
+    it.each([null, undefined])('should return empty object when ctx is %p', (ctx) => {
+      expect(visitor.visit(asVisitCtx(ctx))).toEqual({});
     });
 
     it('should call accept on context when ctx exists', () => {
diff --git a/lana/src/salesforce/codesymbol/__tests__/SfdxProject.test.ts b/lana/src/salesforce/codesymbol/__tests__/SfdxProject.test.ts
index 6143a1f00..88345abbb 100644
--- a/lana/src/salesforce/codesymbol/__tests__/SfdxProject.test.ts
+++ b/lana/src/salesforce/codesymbol/__tests__/SfdxProject.test.ts
@@ -23,7 +23,6 @@ describe('SfdxProject', () => {
   const anotherAppUri = fileUri('/workspace/another-app');
 
   beforeEach(() => {
-    jest.clearAllMocks();
     project = createProject([forceAppUri]);
   });
 
diff --git a/lana/src/salesforce/codesymbol/__tests__/SfdxProjectReader.test.ts b/lana/src/salesforce/codesymbol/__tests__/SfdxProjectReader.test.ts
index 8307b5f12..2a9235252 100644
--- a/lana/src/salesforce/codesymbol/__tests__/SfdxProjectReader.test.ts
+++ b/lana/src/salesforce/codesymbol/__tests__/SfdxProjectReader.test.ts
@@ -29,7 +29,6 @@ describe('getProjects', () => {
   } as WorkspaceFolder;
 
   beforeEach(() => {
-    jest.clearAllMocks();
     // Mirror the real Uri.joinPath: join segments and normalize '..'
     (Uri.joinPath as jest.Mock).mockImplementation((base: Uri, ...segments: string[]) =>
       fileUri(joinPath(base.path, ...segments)),
diff --git a/lana/src/salesforce/codesymbol/__tests__/SymbolFinder.test.ts b/lana/src/salesforce/codesymbol/__tests__/SymbolFinder.test.ts
index abc14537f..3cd9907f6 100644
--- a/lana/src/salesforce/codesymbol/__tests__/SymbolFinder.test.ts
+++ b/lana/src/salesforce/codesymbol/__tests__/SymbolFinder.test.ts
@@ -31,10 +31,6 @@ function createMockWorkspace(findClassResult: Uri[]): VSWorkspace {
 }
 
 describe('SymbolFinder', () => {
-  beforeEach(() => {
-    jest.clearAllMocks();
-  });
-
   describe('findSymbol', () => {
     it('should report not-found when no classes match', async () => {
       const mockWorkspace = createMockWorkspace([]);
diff --git a/lana/src/services/__tests__/salesforceServices.test.ts b/lana/src/services/__tests__/salesforceServices.test.ts
index 823f39351..59ba605a3 100644
--- a/lana/src/services/__tests__/salesforceServices.test.ts
+++ b/lana/src/services/__tests__/salesforceServices.test.ts
@@ -14,7 +14,6 @@ const mockListLogs = jest.fn((limit: number) => ({ limit }));
 const mockGetLogBody = jest.fn((id: string) => ({ id }));
 
 beforeEach(() => {
-  jest.clearAllMocks();
   (getRuntime as jest.Mock).mockReturnValue({ runPromise: mockRunPromise });
   (getServicesApi as jest.Mock).mockReturnValue({
     services: { ApexLogService: { listLogs: mockListLogs, getLogBody: mockGetLogBody } },
diff --git a/lana/src/services/__tests__/servicesRuntime.test.ts b/lana/src/services/__tests__/servicesRuntime.test.ts
index ad7ae2872..34cd862e9 100644
--- a/lana/src/services/__tests__/servicesRuntime.test.ts
+++ b/lana/src/services/__tests__/servicesRuntime.test.ts
@@ -32,7 +32,6 @@ const validApi = () => ({
 
 describe('servicesRuntime', () => {
   beforeEach(() => {
-    jest.clearAllMocks();
     mockGetExtension.mockReturnValue(undefined);
     mockShowErrorMessage.mockResolvedValue(undefined);
   });
diff --git a/lana/src/symbols/__tests__/RawLogSymbolProvider.test.ts b/lana/src/symbols/__tests__/RawLogSymbolProvider.test.ts
index 894133ef0..957374dac 100644
--- a/lana/src/symbols/__tests__/RawLogSymbolProvider.test.ts
+++ b/lana/src/symbols/__tests__/RawLogSymbolProvider.test.ts
@@ -8,6 +8,7 @@ import { SymbolKind, languages } from 'vscode';
 import {
   createMockDisplay,
   createMockApexLog,
+  asContext,
   createMockContext,
   createMockLogEvent,
 } from '../../__tests__/helpers/test-builders.js';
@@ -167,14 +168,14 @@ describe('RawLogSymbolProvider', () => {
   describe('apply', () => {
     const applyProvider = () => {
       const mockContext = createMockContext();
-      RawLogSymbolProvider.apply(mockContext as unknown as import('../../Context.js').Context);
+      RawLogSymbolProvider.apply(asContext(mockContext));
       return (languages.registerDocumentSymbolProvider as jest.Mock).mock.calls[0]?.[1] as
         RawLogSymbolProvider | undefined;
     };
 
     it('gives the registered provider the context display to report through', async () => {
       const mockContext = createMockContext();
-      RawLogSymbolProvider.apply(mockContext as unknown as import('../../Context.js').Context);
+      RawLogSymbolProvider.apply(asContext(mockContext));
       const registered = (languages.registerDocumentSymbolProvider as jest.Mock).mock
         .calls[0]?.[1] as RawLogSymbolProvider;
       mockGetApexLog.mockResolvedValue(null);
diff --git a/lana/src/workspace/__tests__/VSWorkspace.test.ts b/lana/src/workspace/__tests__/VSWorkspace.test.ts
index cbcb3b45c..a42a9d136 100644
--- a/lana/src/workspace/__tests__/VSWorkspace.test.ts
+++ b/lana/src/workspace/__tests__/VSWorkspace.test.ts
@@ -20,7 +20,6 @@ describe('VSWorkspace', () => {
   let vsWorkspace: VSWorkspace;
 
   beforeEach(() => {
-    jest.clearAllMocks();
     vsWorkspace = new VSWorkspace(mockWorkspaceFolder);
   });
 
diff --git a/lana/src/workspace/__tests__/VSWorkspaceManager.test.ts b/lana/src/workspace/__tests__/VSWorkspaceManager.test.ts
index 7927cc857..df98f3a3c 100644
--- a/lana/src/workspace/__tests__/VSWorkspaceManager.test.ts
+++ b/lana/src/workspace/__tests__/VSWorkspaceManager.test.ts
@@ -27,7 +27,6 @@ function createManager(...folders: object[]): VSWorkspaceManager {
 
 describe('VSWorkspaceManager', () => {
   beforeEach(() => {
-    jest.clearAllMocks();
     (workspace as { workspaceFolders?: unknown[] }).workspaceFolders = undefined;
   });
 
diff --git a/log-viewer/src/__tests__/Util.test.ts b/log-viewer/src/__tests__/Util.test.ts
deleted file mode 100644
index f504b9397..000000000
--- a/log-viewer/src/__tests__/Util.test.ts
+++ /dev/null
@@ -1,94 +0,0 @@
-/*
- * Copyright (c) 2020 Certinia Inc. All rights reserved.
- */
-import { describe, expect, it } from '@jest/globals';
-
-import { formatDuration } from '../core/utility/Util.js';
-
-describe('Format duration tests', () => {
-  it('Shows ms with decimals for very small values (sub-millisecond)', () => {
-    expect(formatDuration(5)).toBe('0 ms'); // 0.000005 ms rounds to 0
-    expect(formatDuration(50)).toBe('0 ms'); // 0.00005 ms rounds to 0
-    expect(formatDuration(500)).toBe('0.001 ms');
-    expect(formatDuration(1000)).toBe('0.001 ms');
-    expect(formatDuration(5000)).toBe('0.005 ms');
-    expect(formatDuration(9999)).toBe('0.01 ms');
-    expect(formatDuration(10000)).toBe('0.01 ms');
-    expect(formatDuration(50000)).toBe('0.05 ms');
-    expect(formatDuration(99999)).toBe('0.1 ms');
-  });
-
-  it('handles ms duration', () => {
-    expect(formatDuration(100_000)).toBe('0.1 ms');
-    expect(formatDuration(500_000)).toBe('0.5 ms');
-    expect(formatDuration(1_000_000)).toBe('1 ms');
-    expect(formatDuration(1_234_567)).toBe('1.23 ms');
-    expect(formatDuration(9_999_999)).toBe('10 ms');
-    expect(formatDuration(10_000_000)).toBe('10 ms');
-    expect(formatDuration(99_999_999)).toBe('100 ms');
-    expect(formatDuration(100_000_000)).toBe('100 ms');
-    expect(formatDuration(999_000_000)).toBe('999 ms');
-  });
-
-  it('handles zero duration', () => {
-    expect(formatDuration(0)).toBe('0 ms');
-  });
-
-  it('handles seconds', () => {
-    expect(formatDuration(5_000_000_000)).toBe('5 s');
-    expect(formatDuration(59_500_000_000)).toBe('59.5 s');
-  });
-
-  it('handles minutes and seconds', () => {
-    expect(formatDuration(60_000_000_000)).toBe('1m');
-    expect(formatDuration(125_000_000_000)).toBe('2m 5s');
-    expect(formatDuration(125_500_000_000)).toBe('2m 5.5s');
-  });
-
-  it('handles remove trailing 0 for all units types', () => {
-    expect(formatDuration(5000)).toBe('0.005 ms');
-    expect(formatDuration(100_000)).toBe('0.1 ms');
-    expect(formatDuration(5_000_000_000)).toBe('5 s');
-    expect(formatDuration(60_000_000_000)).toBe('1m');
-  });
-
-  it('handles rounding to appropriate precision', () => {
-    // sub-milliseconds (up to 3 decimal places)
-    expect(formatDuration(1234)).toBe('0.001 ms');
-    expect(formatDuration(9876)).toBe('0.01 ms');
-
-    // milliseconds (up to 2 decimal places)
-    expect(formatDuration(1_234_567)).toBe('1.23 ms');
-    expect(formatDuration(9_876_543)).toBe('9.88 ms');
-
-    // seconds (up to 2 decimal places)
-    expect(formatDuration(1_234_567_890)).toBe('1.23 s');
-    expect(formatDuration(9_876_543_210)).toBe('9.88 s');
-  });
-
-  it('rounds to 1dp for min and s', () => {
-    // minutes with fractional seconds
-    expect(formatDuration(125_670_000_000)).toBe('2m 5.7s');
-  });
-
-  describe('compact option', () => {
-    it('omits spaces for milliseconds', () => {
-      expect(formatDuration(0, { compact: true })).toBe('0ms');
-      expect(formatDuration(50000, { compact: true })).toBe('0.05ms');
-      expect(formatDuration(1_000_000, { compact: true })).toBe('1ms');
-      expect(formatDuration(1_234_567, { compact: true })).toBe('1.23ms');
-      expect(formatDuration(100_000_000, { compact: true })).toBe('100ms');
-    });
-
-    it('omits spaces for seconds', () => {
-      expect(formatDuration(5_000_000_000, { compact: true })).toBe('5s');
-      expect(formatDuration(59_500_000_000, { compact: true })).toBe('59.5s');
-    });
-
-    it('omits spaces for minutes', () => {
-      expect(formatDuration(60_000_000_000, { compact: true })).toBe('1m');
-      expect(formatDuration(125_000_000_000, { compact: true })).toBe('2m5s');
-      expect(formatDuration(125_500_000_000, { compact: true })).toBe('2m5.5s');
-    });
-  });
-});
diff --git a/log-viewer/src/__tests__/helpers/apexLog.ts b/log-viewer/src/__tests__/helpers/apexLog.ts
new file mode 100644
index 000000000..0e036a94b
--- /dev/null
+++ b/log-viewer/src/__tests__/helpers/apexLog.ts
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2026 Certinia Inc. All rights reserved.
+ */
+import { LOG_LEVEL, parse, type ApexLog } from 'apex-log-parser';
+
+import { logStoreFor, type LogStore } from '../../core/log/LogStore.js';
+
+/**
+ * The header line, which decides what the log records. The level comes from the
+ * enum the code under test branches on, so the two cannot drift apart.
+ */
+export const SETTINGS = {
+  finest: `64.0 APEX_CODE,${LOG_LEVEL.Finest};APEX_PROFILING,NONE;DB,NONE\n`,
+  fine: `64.0 APEX_CODE,${LOG_LEVEL.Fine};APEX_PROFILING,NONE;DB,NONE\n`,
+};
+
+/**
+ * `body` inside the execution and code unit a real log wraps it in. The body is
+ * what a test is about, so it stays in the test; this is the envelope that has to
+ * be there for the parser to reach it.
+ *
+ * Stamp the body between 200 and 900000. A duration is `exitStamp - timestamp`,
+ * so a line stamped past the footer gives the code unit a negative one.
+ */
+function logText(body: string, settings = SETTINGS.finest): string {
+  return (
+    settings +
+    '09:18:22.6 (100)|EXECUTION_STARTED\n' +
+    '09:18:22.6 (200)|CODE_UNIT_STARTED|[EXTERNAL]|066d0000002m8ij|apex://pkg.Entry\n' +
+    body +
+    '09:18:22.6 (900000)|CODE_UNIT_FINISHED|apex://pkg.Entry\n' +
+    '09:18:22.6 (901000)|EXECUTION_FINISHED\n'
+  );
+}
+
+/**
+ * {@link logText}, parsed, with the store the components read it through. The
+ * two are one graph: `store.log` is the same object as `log`.
+ */
+export function storeOf(
+  body: string,
+  settings = SETTINGS.finest,
+): { log: ApexLog; store: LogStore } {
+  const log = parse(logText(body, settings));
+  return { log, store: logStoreFor(log) };
+}
+
+/** The eventIndex of the frame or event whose log text is `text`. */
+export function indexOf(log: ApexLog, text: string): number {
+  const found = log.eventsById.find((event) => event.text === text);
+  if (!found) {
+    throw new Error(`no event with text ${text}`);
+  }
+  return found.eventIndex;
+}
+
+/**
+ * Every frame whose log text is `text`, in log order. Frames only: a METHOD_EXIT
+ * carries the same text as the entry it closes.
+ */
+export function indexesOf(log: ApexLog, text: string): number[] {
+  return log.eventsById
+    .filter((event) => event.isParent && event.text === text)
+    .map((event) => event.eventIndex);
+}
diff --git a/log-viewer/src/__tests__/helpers/events.ts b/log-viewer/src/__tests__/helpers/events.ts
new file mode 100644
index 000000000..c4880ec68
--- /dev/null
+++ b/log-viewer/src/__tests__/helpers/events.ts
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2026 Certinia Inc. All rights reserved.
+ */
+import type { LogEvent } from 'apex-log-parser';
+
+/**
+ * The fields the call tree and analysis passes read. Every count is a self/total
+ * pair, so a test names only the half it asserts on and the rest stay zero.
+ */
+export interface EventOptions {
+  text: string;
+  type?: string;
+  namespace?: string;
+  self?: number;
+  total?: number;
+  exitStamp?: number | null;
+  suffix?: string | null;
+  parent?: LogEvent | null;
+  dmlSelf?: number;
+  dmlTotal?: number;
+  soqlSelf?: number;
+  soqlTotal?: number;
+  soslSelf?: number;
+  soslTotal?: number;
+  dmlRowSelf?: number;
+  dmlRowTotal?: number;
+  soqlRowSelf?: number;
+  soqlRowTotal?: number;
+  soslRowSelf?: number;
+  soslRowTotal?: number;
+  thrown?: number;
+  heapSelf?: number;
+  heapTotal?: number;
+}
+
+// Only so two events are told apart in a debugger. Nothing under test reads it,
+// which is why no suite resets it.
+let nextTimestamp = 1;
+
+/**
+ * A `LogEvent` carrying the fields these passes read, and no others. `Partial`
+ * rather than a blind cast, so a renamed or reshaped field on the real class
+ * fails the typecheck here instead of drifting silently.
+ *
+ * Do not add `eventIndex`. A built frame has none, so `keyPathIds.ts:61` finds
+ * `undefined >= 0` false and skips its key cache. Give every frame index 0 — the
+ * real class default — and they all read back the first frame's key.
+ */
+export function createEvent(options: EventOptions): LogEvent {
+  const event: Partial<LogEvent> = {
+    parent: options.parent ?? null,
+    children: [],
+    type: (options.type ?? 'METHOD_ENTRY') as LogEvent['type'],
+    text: options.text,
+    namespace: options.namespace ?? 'default',
+    suffix: options.suffix ?? null,
+    cpuType: '',
+    timestamp: nextTimestamp++,
+    exitStamp: options.exitStamp ?? null,
+    duration: { self: options.self ?? 0, total: options.total ?? 0 },
+    dmlRowCount: { self: options.dmlRowSelf ?? 0, total: options.dmlRowTotal ?? 0 },
+    soqlRowCount: { self: options.soqlRowSelf ?? 0, total: options.soqlRowTotal ?? 0 },
+    soslRowCount: { self: options.soslRowSelf ?? 0, total: options.soslRowTotal ?? 0 },
+    dmlCount: { self: options.dmlSelf ?? 0, total: options.dmlTotal ?? 0 },
+    soqlCount: { self: options.soqlSelf ?? 0, total: options.soqlTotal ?? 0 },
+    soslCount: { self: options.soslSelf ?? 0, total: options.soslTotal ?? 0 },
+    thrownCount: { self: options.thrown ?? 0, total: options.thrown ?? 0 },
+    heapAllocated: { self: options.heapSelf ?? 0, total: options.heapTotal ?? 0 },
+    heapGross: { self: 0, total: 0 },
+    heapPeak: 0,
+  };
+
+  const built = event as LogEvent;
+  options.parent?.children.push(built);
+  return built;
+}
diff --git a/log-viewer/src/__tests__/helpers/flameChart.ts b/log-viewer/src/__tests__/helpers/flameChart.ts
new file mode 100644
index 000000000..c6fd2942e
--- /dev/null
+++ b/log-viewer/src/__tests__/helpers/flameChart.ts
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2026 Certinia Inc. All rights reserved.
+ */
+import { jest } from '@jest/globals';
+
+import type { FlameChart } from '../../features/timeline/optimised/FlameChart.js';
+import type { RenderDirtyState } from '../../features/timeline/types/flamechart.types.js';
+
+/**
+ * The chart's private fields, writable. Reaching past the public API is what
+ * these suites are for: they drive `render` and `resize` without a canvas.
+ */
+export function internalsOf(chart: FlameChart): Record<string, unknown> {
+  return chart as unknown as Record<string, unknown>;
+}
+
+/**
+ * The private collaborators no suite varies, stubbed, and the same record back to
+ * write the rest onto. `app`, `viewport` and the hit-test collaborators stay with
+ * the suite, which needs a different handle on each to observe its own case.
+ *
+ * Naming the shared fields once means a rename inside FlameChart lands here
+ * rather than in each suite.
+ *
+ * Every dirty flag starts false, unlike the real `init()`, so a case proves the
+ * render it asked for rather than the one init already asked for. `dirty` names
+ * the flags a case does depend on.
+ */
+export function stubChartInternals(
+  chart: FlameChart,
+  dirty: Partial<RenderDirtyState> = {},
+): Record<string, unknown> {
+  const internals = internalsOf(chart);
+  internals['container'] = document.createElement('div');
+  internals['index'] = { maxDepth: 1 };
+  internals['worldContainer'] = { position: { set: jest.fn() } };
+  internals['batchRenderer'] = { render: jest.fn(), clear: jest.fn() };
+  internals['rectangleManager'] = {
+    getCulledRectangles: () => ({ visibleRects: new Map(), buckets: new Map() }),
+  };
+  internals['state'] = {
+    needsRender: false,
+    batchColorsCache: new Map(),
+    renderDirty: {
+      background: false,
+      culling: false,
+      eventRendering: false,
+      highlights: false,
+      overlays: false,
+      minimap: false,
+      metricStrip: false,
+      ...dirty,
+    },
+  };
+  return internals;
+}
diff --git a/log-viewer/src/__tests__/helpers/mount.ts b/log-viewer/src/__tests__/helpers/mount.ts
new file mode 100644
index 000000000..8bf87d45b
--- /dev/null
+++ b/log-viewer/src/__tests__/helpers/mount.ts
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2026 Certinia Inc. All rights reserved.
+ */
+import type { LitElement } from 'lit';
+
+/** Props to assign, or a callback for a suite that needs more than assignment. */
+type Configure<T> = Partial<T> | ((element: T) => void);
+
+/**
+ * Create a custom element, configure it, put it in the document and wait for its first
+ * render. A suite needing more settling than one render awaits it itself, so the extra
+ * wait stays where a reader can see what it is for.
+ *
+ * The tag is a string, not a `HTMLElementTagNameMap` key: 44 of the 65 components declare
+ * no map entry, so the element type is named at the call site.
+ */
+export async function mountElement<T extends LitElement>(
+  tag: string,
+  configure?: Configure<T>,
+): Promise<T> {
+  const element = document.createElement(tag) as unknown as T;
+  if (!('updateComplete' in element)) {
+    // Without this, a tag that is unregistered or registered to a non-Lit element awaits its
+    // undefined `updateComplete` happily and the suite fails later on a null shadowRoot. The
+    // usual cause is a missing side-effect `import '../Thing.js'`: a type-only import of the
+    // class is elided, so the module never runs and never registers.
+    throw new Error(`<${tag}> is not a rendered Lit element — is its module imported?`);
+  }
+  if (typeof configure === 'function') {
+    configure(element);
+  } else if (configure) {
+    Object.assign(element, configure);
+  }
+  document.body.appendChild(element);
+  await element.updateComplete;
+  return element;
+}
diff --git a/log-viewer/src/__tests__/helpers/viewport.ts b/log-viewer/src/__tests__/helpers/viewport.ts
new file mode 100644
index 000000000..d0a3711ed
--- /dev/null
+++ b/log-viewer/src/__tests__/helpers/viewport.ts
@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2026 Certinia Inc. All rights reserved.
+ */
+import type { ViewportState } from '../../features/timeline/types/flamechart.types.js';
+
+/**
+ * A viewport a test can vary one field of. The canvas a renderer measures against
+ * is stated here once, so a case that does depend on its size says so by passing it.
+ */
+export function makeViewport(over: Partial<ViewportState> = {}): ViewportState {
+  return {
+    zoom: 1,
+    offsetX: 0,
+    offsetY: 0,
+    displayWidth: 1000,
+    displayHeight: 600,
+    ...over,
+  };
+}
diff --git a/log-viewer/src/__tests__/mocks/vscodeElementStub.ts b/log-viewer/src/__tests__/mocks/vscodeElementStub.ts
new file mode 100644
index 000000000..8f503c8c7
--- /dev/null
+++ b/log-viewer/src/__tests__/mocks/vscodeElementStub.ts
@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) 2026 Certinia Inc. All rights reserved.
+ */
+
+/**
+ * Stands in for a `#vscode-elements/*` import under jest. The real modules register custom
+ * elements jsdom cannot construct, and an importer only needs the tag to exist in its
+ * template — an unregistered tag renders as an unknown element and loses no coverage.
+ */
+export {};
diff --git a/log-viewer/src/__tests__/setup.ts b/log-viewer/src/__tests__/setup.ts
index c25f5ca09..538ec287e 100644
--- a/log-viewer/src/__tests__/setup.ts
+++ b/log-viewer/src/__tests__/setup.ts
@@ -16,3 +16,18 @@ class NoopResizeObserver implements ResizeObserver {
 if (!('ResizeObserver' in globalThis)) {
   (globalThis as unknown as Record<string, unknown>).ResizeObserver = NoopResizeObserver;
 }
+
+/**
+ * A mounted component stays connected until something removes it, and its
+ * `connectedCallback` subscriptions stay live with it. One test's leftovers then
+ * hear the next test's events. `replaceChildren` over `innerHTML = ''` so
+ * `disconnectedCallback` runs and the subscriptions actually release.
+ *
+ * The suites run under `node` unless a file asks for jsdom, so there is not
+ * always a document.
+ */
+if (typeof document !== 'undefined') {
+  afterEach(() => {
+    document.body.replaceChildren();
+  });
+}
diff --git a/log-viewer/src/components/VsSelect.ts b/log-viewer/src/components/VsSelect.ts
index 92ccbc564..5b7ec0864 100644
--- a/log-viewer/src/components/VsSelect.ts
+++ b/log-viewer/src/components/VsSelect.ts
@@ -232,6 +232,10 @@ export const selectSizingStyles = css`
 `;
 
 /** vscode-single-select where the control fits the selected value and the popup its widest option. */
+// jest.config.js stubs every `#vscode-elements/*` module and exempts this one, because a stub
+// cannot be extended. A new component that extends a vendor element needs the same exemption.
+// The exemption keeps the real element, which is form-associated: a suite that mounts
+// `<vs-select>` has to shim `ElementInternals.setFormValue`, absent in jsdom.
 @customElement('vs-select')
 export class VsSelect extends VscodeSingleSelect {
   static styles = [...VscodeSingleSelect.styles, ...globalStyles, selectSizingStyles];
diff --git a/log-viewer/src/components/__tests__/AnchoredPopover.test.ts b/log-viewer/src/components/__tests__/AnchoredPopover.test.ts
index 1dbea84d6..2f423fc41 100644
--- a/log-viewer/src/components/__tests__/AnchoredPopover.test.ts
+++ b/log-viewer/src/components/__tests__/AnchoredPopover.test.ts
@@ -5,22 +5,19 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-// jsdom can't run the real elements (they read document.baseURI / setFormValue).
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { AnchoredPopover } from '../AnchoredPopover.js';
 import '../AnchoredPopover.js';
 
 async function mount(panelContent: string, showHeading = false): Promise<AnchoredPopover> {
-  const el = document.createElement('anchored-popover') as AnchoredPopover;
-  el.heading = 'Log problems';
-  el.emptyMessage = 'No problems found in this log';
-  if (showHeading) {
-    el.setAttribute('show-heading', '');
-  }
-  el.innerHTML = `<span slot="trigger">face</span>${panelContent}`;
-  document.body.appendChild(el);
-  await el.updateComplete;
+  const el = await mountElement<AnchoredPopover>('anchored-popover', (e) => {
+    e.heading = 'Log problems';
+    e.emptyMessage = 'No problems found in this log';
+    if (showHeading) {
+      e.setAttribute('show-heading', '');
+    }
+    e.innerHTML = `<span slot="trigger">face</span>${panelContent}`;
+  });
   // The panel slot is only readable after the first render, which schedules a second.
   await el.updateComplete;
   return el;
diff --git a/log-viewer/src/components/__tests__/CallStackDetail.test.ts b/log-viewer/src/components/__tests__/CallStackDetail.test.ts
index 802bce40b..ecde5bb4c 100644
--- a/log-viewer/src/components/__tests__/CallStackDetail.test.ts
+++ b/log-viewer/src/components/__tests__/CallStackDetail.test.ts
@@ -41,6 +41,7 @@ jest.mock('../callStackData.js', () => ({
   buildCallStackData: () => ({ rows: [], rootTotal: 0 }),
 }));
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { CallStackDetail } from '../CallStackDetail.js';
 import '../CallStackDetail.js';
 import {
@@ -50,13 +51,8 @@ import {
   type InspectorRevealEvent,
 } from '../inspectorReveal.js';
 
-async function mount(eventIndex: number): Promise<CallStackDetail> {
-  const el = document.createElement('call-stack-detail') as CallStackDetail;
-  el.eventIndex = eventIndex;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (eventIndex: number): Promise<CallStackDetail> =>
+  mountElement<CallStackDetail>('call-stack-detail', { eventIndex });
 
 describe('CallStackDetail', () => {
   it('renders the table host and a context menu for the row actions', async () => {
diff --git a/log-viewer/src/components/__tests__/CallTreeDetail.test.ts b/log-viewer/src/components/__tests__/CallTreeDetail.test.ts
index 868b878db..e1e394f99 100644
--- a/log-viewer/src/components/__tests__/CallTreeDetail.test.ts
+++ b/log-viewer/src/components/__tests__/CallTreeDetail.test.ts
@@ -18,11 +18,10 @@ jest.mock('tabulator-tables', () => ({
   Module: class {},
   Renderer: class {},
 }));
-// vscode-button needs ElementInternals.setFormValue (absent in jsdom).
-jest.mock('#vscode-elements/vscode-button.js', () => ({}));
 
 import type { CellComponent } from 'tabulator-tables';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { LogStore } from '../../core/log/LogStore.js';
 import type { CallTreeDetail } from '../CallTreeDetail.js';
 import '../CallTreeDetail.js';
@@ -64,15 +63,12 @@ function nameTooltip(
 const thisLog = {} as LogStore;
 const nextLog = {} as LogStore;
 
-async function mount(props: Partial<CallTreeDetail> = {}): Promise<CallTreeDetail> {
-  const el = document.createElement('call-tree-detail') as CallTreeDetail;
-  el.eventIndex = -1; // no selection in the test — no table is built
-  el.logStore = thisLog;
-  Object.assign(el, props);
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (props: Partial<CallTreeDetail> = {}): Promise<CallTreeDetail> =>
+  mountElement<CallTreeDetail>('call-tree-detail', {
+    eventIndex: -1, // no selection in the test — no table is built
+    logStore: thisLog,
+    ...props,
+  });
 
 async function pick(el: CallTreeDetail, value: string): Promise<void> {
   switchEl(el).dispatchEvent(
diff --git a/log-viewer/src/components/__tests__/CallTreeDetailScopedBuild.test.ts b/log-viewer/src/components/__tests__/CallTreeDetailScopedBuild.test.ts
index 173cfac11..472435928 100644
--- a/log-viewer/src/components/__tests__/CallTreeDetailScopedBuild.test.ts
+++ b/log-viewer/src/components/__tests__/CallTreeDetailScopedBuild.test.ts
@@ -28,8 +28,6 @@ jest.mock('tabulator-tables', () => {
   }
   return { Tabulator, Module: class {}, Renderer: class {} };
 });
-// vscode-button needs ElementInternals.setFormValue (absent in jsdom).
-jest.mock('#vscode-elements/vscode-button.js', () => ({}));
 
 // The walk is what this suite is about, so it's stubbed; each test says whether
 // it yields a tree or nothing, and when.
@@ -44,6 +42,8 @@ jest.mock('../scopedCallTree.js', () => ({
 
 import { Tabulator, type RowComponent } from 'tabulator-tables';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
+import { waitForNextFrame } from '../../core/utility/FrameBudget.js';
 import type { CallTreeDetail } from '../CallTreeDetail.js';
 import '../CallTreeDetail.js';
 import { buildScopedCallTree, type ScopedCallTree, type ScopedRow } from '../scopedCallTree.js';
@@ -113,25 +113,15 @@ async function settle(el: CallTreeDetail): Promise<void> {
 
 /** Lets the rAF the build waits behind fire, then settles the render. */
 async function frame(el: CallTreeDetail): Promise<void> {
-  await new Promise((resolve) => requestAnimationFrame(resolve));
+  await waitForNextFrame();
   await settle(el);
 }
 
-async function mount(
-  eventIndex: number,
-  sourceView?: 'callers' | 'callees',
-): Promise<CallTreeDetail> {
-  const el = document.createElement('call-tree-detail') as CallTreeDetail;
-  el.eventIndex = eventIndex;
-  el.sourceView = sourceView;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (eventIndex: number, sourceView?: 'callers' | 'callees'): Promise<CallTreeDetail> =>
+  mountElement<CallTreeDetail>('call-tree-detail', { eventIndex, sourceView });
 
 describe('CallTreeDetail scoped build', () => {
   beforeEach(() => {
-    document.body.replaceChildren();
     build.mockReset();
     build.mockResolvedValue(null);
     tables.instances.length = 0;
diff --git a/log-viewer/src/components/__tests__/CodeBlock.test.ts b/log-viewer/src/components/__tests__/CodeBlock.test.ts
index 2650779c0..20d3e068c 100644
--- a/log-viewer/src/components/__tests__/CodeBlock.test.ts
+++ b/log-viewer/src/components/__tests__/CodeBlock.test.ts
@@ -5,18 +5,12 @@
  */
 import { beforeAll, describe, expect, it } from '@jest/globals';
 
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { CodeBlock } from '../CodeBlock.js';
 import '../CodeBlock.js';
 
-async function mount(configure: (el: CodeBlock) => void): Promise<CodeBlock> {
-  const el = document.createElement('code-block') as CodeBlock;
-  configure(el);
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (configure: (el: CodeBlock) => void): Promise<CodeBlock> =>
+  mountElement<CodeBlock>('code-block', configure);
 
 describe('CodeBlock', () => {
   beforeAll(() => {
diff --git a/log-viewer/src/components/__tests__/ColorSwatch.test.ts b/log-viewer/src/components/__tests__/ColorSwatch.test.ts
index 86983422e..5dc906b02 100644
--- a/log-viewer/src/components/__tests__/ColorSwatch.test.ts
+++ b/log-viewer/src/components/__tests__/ColorSwatch.test.ts
@@ -5,16 +5,12 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { ColorSwatch } from '../ColorSwatch.js';
 import '../ColorSwatch.js';
 
-async function mount(props: Partial<Pick<ColorSwatch, 'color'>> = {}) {
-  const element = document.createElement('color-swatch');
-  Object.assign(element, props);
-  document.body.appendChild(element);
-  await element.updateComplete;
-  return element;
-}
+const mount = (props: Partial<Pick<ColorSwatch, 'color'>> = {}) =>
+  mountElement<ColorSwatch>('color-swatch', props);
 
 describe('ColorSwatch', () => {
   it('paints itself in the colour it is given', async () => {
diff --git a/log-viewer/src/components/__tests__/DetailDock.test.ts b/log-viewer/src/components/__tests__/DetailDock.test.ts
index c9539d306..becd34d21 100644
--- a/log-viewer/src/components/__tests__/DetailDock.test.ts
+++ b/log-viewer/src/components/__tests__/DetailDock.test.ts
@@ -6,9 +6,7 @@
 import { beforeAll, describe, expect, it } from '@jest/globals';
 import { html } from 'lit';
 
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-jest.mock('#vscode-elements/vscode-badge.js', () => ({}));
-
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { DetailDock } from '../DetailDock.js';
 import '../DetailDock.js';
 import type { PaneSection } from '../PaneView.js';
@@ -18,13 +16,8 @@ const sections: PaneSection[] = [
   { id: 'b', title: 'B', content: html`<div>b</div>` },
 ];
 
-async function mount(configure: (el: DetailDock) => void): Promise<DetailDock> {
-  const el = document.createElement('detail-dock') as DetailDock;
-  configure(el);
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (configure: (el: DetailDock) => void): Promise<DetailDock> =>
+  mountElement<DetailDock>('detail-dock', configure);
 
 describe('DetailDock', () => {
   beforeAll(() => {
diff --git a/log-viewer/src/components/__tests__/DockLayout.test.ts b/log-viewer/src/components/__tests__/DockLayout.test.ts
index edcab3e47..22ed1e084 100644
--- a/log-viewer/src/components/__tests__/DockLayout.test.ts
+++ b/log-viewer/src/components/__tests__/DockLayout.test.ts
@@ -5,9 +5,7 @@
  */
 import { describe, expect, it, beforeAll } from '@jest/globals';
 
-// <detail-dock> pulls in vscode-elements icons, which need APIs jsdom lacks.
-jest.mock('../DetailDock.js', () => ({}));
-
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { DockLayout } from '../DockLayout.js';
 import '../DockLayout.js';
 
@@ -25,15 +23,8 @@ beforeAll(() => {
   Object.defineProperty(HTMLElement.prototype, 'clientHeight', { value: 800, configurable: true });
 });
 
-async function mount(dock: 'left' | 'right' | 'bottom', size = 500): Promise<DockLayout> {
-  const el = document.createElement('dock-layout') as DockLayout;
-  el.dock = dock;
-  el.size = size;
-  el.visible = true;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (dock: 'left' | 'right' | 'bottom', size = 500): Promise<DockLayout> =>
+  mountElement<DockLayout>('dock-layout', { dock, size, visible: true });
 
 function gutter(el: DockLayout): HTMLElement {
   const found = el.shadowRoot?.querySelector('.gutter');
diff --git a/log-viewer/src/components/__tests__/EventVitals.test.ts b/log-viewer/src/components/__tests__/EventVitals.test.ts
index be3de3b91..e7ee5751f 100644
--- a/log-viewer/src/components/__tests__/EventVitals.test.ts
+++ b/log-viewer/src/components/__tests__/EventVitals.test.ts
@@ -6,6 +6,7 @@
 import { beforeAll, describe, expect, it } from '@jest/globals';
 import { parse } from 'apex-log-parser';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import { logStoreFor, type LogStore } from '../../core/log/LogStore.js';
 
 // Avoid the heavy CodeBlock import chain (vscode-elements, soql formatter); the
@@ -42,13 +43,8 @@ function valueFor(el: EventVitals, label: string): string | undefined {
 }
 
 /** No provider in the test, so the consumed store is assigned straight on. */
-async function mount(store: LogStore, props: Partial<EventVitals>): Promise<EventVitals> {
-  const el = document.createElement('event-vitals') as EventVitals;
-  Object.assign(el, { logStore: store }, props);
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (store: LogStore, props: Partial<EventVitals>): Promise<EventVitals> =>
+  mountElement<EventVitals>('event-vitals', { logStore: store, ...props });
 
 describe('EventVitals', () => {
   let store: LogStore;
diff --git a/log-viewer/src/components/__tests__/GovernorTrends.test.ts b/log-viewer/src/components/__tests__/GovernorTrends.test.ts
index 01b342d52..94822730b 100644
--- a/log-viewer/src/components/__tests__/GovernorTrends.test.ts
+++ b/log-viewer/src/components/__tests__/GovernorTrends.test.ts
@@ -6,6 +6,7 @@
 import { beforeEach, describe, expect, it } from '@jest/globals';
 import type { LitElement } from 'lit';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import { eventBus } from '../../core/events/EventBus.js';
 import type { LogStore } from '../../core/log/LogStore.js';
 import type { TrendSeries } from '../governorTrendData.js';
@@ -21,6 +22,7 @@ jest.mock('../../features/timeline/optimised/apex-limit-series.js', () => ({
   apexLimitTimeSeries: () => ({ events: [] }),
 }));
 
+import type { GovernorTrends } from '../GovernorTrends.js';
 import '../GovernorTrends.js';
 
 const LOG_NS = 1_000;
@@ -40,14 +42,9 @@ const trend = (label = 'SOQL queries'): TrendSeries => ({
 
 const aLog = () => ({ log: { duration: { total: LOG_NS } } }) as unknown as LogStore;
 
-async function mount(): Promise<LitElement> {
-  const element = document.createElement('governor-trends');
+const mount = (): Promise<GovernorTrends> =>
   // No provider in the test, so the consumed store is assigned straight on.
-  (element as unknown as { logStore: LogStore }).logStore = aLog();
-  document.body.append(element);
-  await element.updateComplete;
-  return element;
-}
+  mountElement<GovernorTrends>('governor-trends', { logStore: aLog() });
 
 /** The chart, given a width so a pointer x maps to a time. */
 function chartOf(element: LitElement, at = 0): HTMLButtonElement {
@@ -73,7 +70,6 @@ let seeks: { timestamp?: number; mode?: string }[];
 let unsubscribe: () => void;
 
 beforeEach(() => {
-  document.body.replaceChildren();
   series = [trend()];
   seeks = [];
   unsubscribe?.();
@@ -304,18 +300,13 @@ describe('governor-trends', () => {
       return [...classes].find((name) => name.startsWith('trend--')) ?? null;
     };
 
-    it('reads safe below the warn threshold', async () => {
-      expect(await tierOf(79)).toBe('trend--safe');
-    });
-
-    it('warns from the threshold', async () => {
+    // Where the bands fall is proved once, in
+    // features/database/components/__tests__/GovernorSummary.test.ts. This proves the
+    // trend applies them, and that finalRatio reaches governorTier as a percent.
+    it('puts the tier the policy gives on the figure', async () => {
       expect(await tierOf(80)).toBe('trend--warn');
     });
 
-    it('reads danger at the limit', async () => {
-      expect(await tierOf(100)).toBe('trend--danger');
-    });
-
     // No limit, so no tier to report against.
     it('takes none where the log reported no limit', async () => {
       expect(await tierOf(90, 0)).toBeNull();
diff --git a/log-viewer/src/components/__tests__/HeaderMenu.test.ts b/log-viewer/src/components/__tests__/HeaderMenu.test.ts
index c569a1344..37f514b03 100644
--- a/log-viewer/src/components/__tests__/HeaderMenu.test.ts
+++ b/log-viewer/src/components/__tests__/HeaderMenu.test.ts
@@ -5,25 +5,16 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-// jsdom can't run the real elements (they read document.baseURI / setFormValue).
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { HeaderMenu } from '../HeaderMenu.js';
 import '../HeaderMenu.js';
 
-async function mount(
+const mount = (
   marker: boolean,
   collapsed = '',
   collapsedCount = collapsed ? 1 : 0,
-): Promise<HeaderMenu> {
-  const el = document.createElement('header-menu') as HeaderMenu;
-  el.marker = marker;
-  el.collapsedCount = collapsedCount;
-  el.innerHTML = collapsed;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+): Promise<HeaderMenu> =>
+  mountElement<HeaderMenu>('header-menu', { marker, collapsedCount, innerHTML: collapsed });
 
 function rowLabels(el: HeaderMenu): string[] {
   return Array.from(el.shadowRoot?.querySelectorAll('.filter-popover-row') ?? []).map(
diff --git a/log-viewer/src/components/__tests__/HotPath.test.ts b/log-viewer/src/components/__tests__/HotPath.test.ts
index 0f9f3b5d4..e36a628e9 100644
--- a/log-viewer/src/components/__tests__/HotPath.test.ts
+++ b/log-viewer/src/components/__tests__/HotPath.test.ts
@@ -5,11 +5,10 @@
  */
 import { beforeEach, describe, expect, it } from '@jest/globals';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { LogStore } from '../../core/log/LogStore.js';
 import type { ExecutionHighlights } from '../../features/call-tree/utils/ExecutionHighlights.js';
 
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-
 let highlights: ExecutionHighlights | null = null;
 jest.mock('../../features/call-tree/utils/ExecutionHighlights.js', () => ({
   getExecutionHighlights: () => highlights,
@@ -37,13 +36,10 @@ const pathOf = (frameCount: number): ExecutionHighlights => ({
   truncation: null,
 });
 
-const hotPath = async () => {
-  const element = document.createElement('hot-path');
-  element.logStore = { log: {} } as unknown as LogStore;
-  document.body.append(element);
-  await element.updateComplete;
-  return element;
-};
+const hotPath = () =>
+  mountElement<HTMLElementTagNameMap['hot-path']>('hot-path', {
+    logStore: { log: {} } as unknown as LogStore,
+  });
 
 const rowNames = (element: Element) =>
   [...element.shadowRoot!.querySelectorAll('.reveal-row__name')].map((name) => name.textContent);
@@ -61,7 +57,6 @@ const rowCaptions = (element: Element) =>
 
 describe('hot-path', () => {
   beforeEach(() => {
-    document.body.replaceChildren();
     highlights = null;
   });
 
diff --git a/log-viewer/src/components/__tests__/HotSpots.test.ts b/log-viewer/src/components/__tests__/HotSpots.test.ts
index 874502943..1dcd0eadc 100644
--- a/log-viewer/src/components/__tests__/HotSpots.test.ts
+++ b/log-viewer/src/components/__tests__/HotSpots.test.ts
@@ -5,6 +5,7 @@
  */
 import { beforeEach, describe, expect, it } from '@jest/globals';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { LogStore } from '../../core/log/LogStore.js';
 import type { ExecutionHighlights } from '../../features/call-tree/utils/ExecutionHighlights.js';
 
@@ -34,17 +35,13 @@ const spotsOf = (): ExecutionHighlights => ({
   truncation: null,
 });
 
-const hotSpots = async () => {
-  const element = document.createElement('hot-spots');
-  element.logStore = { log: {} } as unknown as LogStore;
-  document.body.append(element);
-  await element.updateComplete;
-  return element;
-};
+const hotSpots = () =>
+  mountElement<HTMLElementTagNameMap['hot-spots']>('hot-spots', {
+    logStore: { log: {} } as unknown as LogStore,
+  });
 
 describe('hot-spots', () => {
   beforeEach(() => {
-    document.body.replaceChildren();
     highlights = null;
   });
 
diff --git a/log-viewer/src/components/__tests__/LogInspector.test.ts b/log-viewer/src/components/__tests__/LogInspector.test.ts
index cd156ad0f..2de60b82a 100644
--- a/log-viewer/src/components/__tests__/LogInspector.test.ts
+++ b/log-viewer/src/components/__tests__/LogInspector.test.ts
@@ -6,9 +6,6 @@
 import { beforeEach, describe, expect, it } from '@jest/globals';
 import { html } from 'lit';
 
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-jest.mock('#vscode-elements/vscode-badge.js', () => ({}));
-jest.mock('#vscode-elements/vscode-button.js', () => ({}));
 // The swc transform can't parse `.scss`/`.css`; stub the stylesheet assets.
 jest.mock('../../tabulator/style/DataGrid.scss', () => ({ default: '' }));
 jest.mock('../../tabulator/format/Progress.css', () => ({}));
@@ -79,6 +76,8 @@ jest.mock('../detailSections.js', () => ({
   },
 }));
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
+import { waitForNextFrame } from '../../core/utility/FrameBudget.js';
 import { eventBus, type DetailSource } from '../../core/events/EventBus.js';
 import type { LogStore } from '../../core/log/LogStore.js';
 import type { LogInspector } from '../LogInspector.js';
@@ -102,7 +101,7 @@ async function settle(el: LogInspector): Promise<void> {
 
 /** `settle`, plus the rAF wait that lets the debounced rebuild fire first. */
 async function flush(el: LogInspector): Promise<void> {
-  await new Promise((resolve) => requestAnimationFrame(resolve));
+  await waitForNextFrame();
   await settle(el);
 }
 
@@ -112,9 +111,7 @@ function inspectorSettings(overrides: Record<string, unknown> = {}): Record<stri
 }
 
 async function mount(activeTab: string): Promise<LogInspector> {
-  const el = document.createElement('log-inspector') as LogInspector;
-  el.activeTab = activeTab;
-  document.body.appendChild(el);
+  const el = await mountElement<LogInspector>('log-inspector', { activeTab });
   await flush(el);
   return el;
 }
@@ -229,7 +226,6 @@ describe('LogInspector', () => {
     deferSections = false;
     pendingSections.length = 0;
     builtHiding.length = 0;
-    document.body.replaceChildren();
   });
 
   it('applies the persisted collapse to the list it was made in', async () => {
@@ -397,7 +393,7 @@ describe('LogInspector', () => {
     // awaited; the toggle must not be undone when that build lands.
     deferSections = true;
     select('timeline', 2);
-    await new Promise((resolve) => requestAnimationFrame(resolve));
+    await waitForNextFrame();
     openSectionMenu(el);
     pickMenuItem(el, 'section:callstack');
     await settle(el);
@@ -860,9 +856,9 @@ describe('LogInspector', () => {
     deferSections = true;
 
     select('timeline', 1);
-    await new Promise((resolve) => requestAnimationFrame(resolve)); // debounce fires -> _rebuild() epoch 1 starts, awaiting buildDetailSections
+    await waitForNextFrame(); // debounce fires -> _rebuild() epoch 1 starts, awaiting buildDetailSections
     select('timeline', 2);
-    await new Promise((resolve) => requestAnimationFrame(resolve)); // debounce fires -> _rebuild() epoch 2 starts, awaiting buildDetailSections
+    await waitForNextFrame(); // debounce fires -> _rebuild() epoch 2 starts, awaiting buildDetailSections
     expect(pendingSections).toHaveLength(2);
 
     // The newer selection's build resolves first (it's the one the user is
diff --git a/log-viewer/src/components/__tests__/LogOverview.test.ts b/log-viewer/src/components/__tests__/LogOverview.test.ts
index fada16750..018033280 100644
--- a/log-viewer/src/components/__tests__/LogOverview.test.ts
+++ b/log-viewer/src/components/__tests__/LogOverview.test.ts
@@ -6,6 +6,7 @@
 import type { GovernorLimits } from 'apex-log-parser';
 import { beforeEach, describe, expect, it } from '@jest/globals';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { LogStore } from '../../core/log/LogStore.js';
 import type { HeatStripTimeSeries } from '../../features/timeline/types/flamechart.types.js';
 import { emptyLimits, seriesEvent, timeSeries } from './limitsTestUtils.js';
@@ -20,12 +21,7 @@ jest.mock('../../features/timeline/optimised/apex-limit-series.js', () => ({
 import type { LogOverview } from '../LogOverview.js';
 import '../LogOverview.js';
 
-const overview = async () => {
-  const element = document.createElement('log-overview');
-  document.body.append(element);
-  await element.updateComplete;
-  return element;
-};
+const overview = () => mountElement<LogOverview>('log-overview');
 
 /** No provider in the test, so the consumed store is assigned straight on. */
 const loadLog = async (element: LogOverview, governorLimits: GovernorLimits) => {
@@ -35,7 +31,6 @@ const loadLog = async (element: LogOverview, governorLimits: GovernorLimits) =>
 
 describe('log-overview', () => {
   beforeEach(() => {
-    document.body.replaceChildren();
     mockSeries = timeSeries();
   });
 
diff --git a/log-viewer/src/components/__tests__/LogProblemsChip.test.ts b/log-viewer/src/components/__tests__/LogProblemsChip.test.ts
index 0ac2c28fd..df7dd2e03 100644
--- a/log-viewer/src/components/__tests__/LogProblemsChip.test.ts
+++ b/log-viewer/src/components/__tests__/LogProblemsChip.test.ts
@@ -5,10 +5,7 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-// jsdom can't run the real elements (they read document.baseURI / setFormValue).
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-jest.mock('#vscode-elements/vscode-button.js', () => ({}));
-
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { IssueSeverity, LogIssue } from '../../features/notifications/types.js';
 
 import type { LogProblemsChip } from '../LogProblemsChip.js';
@@ -26,13 +23,8 @@ function issue(severity: IssueSeverity): LogIssue {
   };
 }
 
-async function mount(issues: readonly LogIssue[] | null): Promise<LogProblemsChip> {
-  const el = document.createElement('log-problems') as LogProblemsChip;
-  el.issues = issues;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (issues: readonly LogIssue[] | null): Promise<LogProblemsChip> =>
+  mountElement<LogProblemsChip>('log-problems', { issues });
 
 function chip(el: LogProblemsChip): HTMLElement | null {
   return el.shadowRoot?.querySelector('.header-control') ?? null;
diff --git a/log-viewer/src/components/__tests__/NamespaceTimeBar.test.ts b/log-viewer/src/components/__tests__/NamespaceTimeBar.test.ts
index ca4cde2af..da5a47979 100644
--- a/log-viewer/src/components/__tests__/NamespaceTimeBar.test.ts
+++ b/log-viewer/src/components/__tests__/NamespaceTimeBar.test.ts
@@ -8,6 +8,7 @@ import type { ApexLog } from 'apex-log-parser';
 
 let apexLog: ApexLog | null = null;
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { LogStore } from '../../core/log/LogStore.js';
 import type { NamespaceTimeBar } from '../NamespaceTimeBar.js';
 import { DEFAULT_MAX_SEGMENTS } from '../StackedTimeBar.js';
@@ -20,7 +21,6 @@ const logOf = (children: FakeEvent[], namespaces: string[]) => {
 };
 
 async function mount(props: Partial<Pick<NamespaceTimeBar, 'eventIndex' | 'instances'>> = {}) {
-  const element = document.createElement('namespace-time-bar');
   // No provider in the test, so the consumed store is assigned straight on.
   const store =
     apexLog &&
@@ -28,8 +28,10 @@ async function mount(props: Partial<Pick<NamespaceTimeBar, 'eventIndex' | 'insta
       log: apexLog,
       eventByIndex: (index: number) => eventByIndex(index),
     } as unknown as LogStore);
-  Object.assign(element, { logStore: store }, props);
-  document.body.append(element);
+  const element = await mountElement<NamespaceTimeBar>('namespace-time-bar', {
+    logStore: store,
+    ...props,
+  });
   // The first render only starts the walk; the result lands a task later.
   for (let settle = 0; settle < 5; settle++) {
     await element.updateComplete;
@@ -46,7 +48,6 @@ const segments = (element: NamespaceTimeBar) => bar(element)?.segments ?? [];
 
 describe('namespace-time-bar', () => {
   beforeEach(() => {
-    document.body.replaceChildren();
     resetEvents();
     apexLog = null;
   });
diff --git a/log-viewer/src/components/__tests__/NavBar.test.ts b/log-viewer/src/components/__tests__/NavBar.test.ts
index 3e2756a1d..dd5863204 100644
--- a/log-viewer/src/components/__tests__/NavBar.test.ts
+++ b/log-viewer/src/components/__tests__/NavBar.test.ts
@@ -5,11 +5,7 @@
  */
 import { afterAll, beforeAll, beforeEach, describe, expect, it } from '@jest/globals';
 
-// jsdom can't run the real elements (they read document.baseURI / setFormValue).
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-jest.mock('#vscode-elements/vscode-toolbar-button.js', () => ({}));
-jest.mock('#vscode-elements/vscode-button.js', () => ({}));
-
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { LogIdentityData } from '../../features/app/logIdentity.js';
 import type { IssueSeverity, LogIssue } from '../../features/notifications/types.js';
 
@@ -116,18 +112,15 @@ function issue(severity: IssueSeverity): LogIssue {
   };
 }
 
-async function mount(
+const mount = (
   problems: readonly LogIssue[] = [],
   notifications: readonly LogIssue[] = [],
-): Promise<NavBar> {
-  const el = document.createElement('nav-bar') as NavBar;
-  el.logName = 'test.log';
-  el.logProblems = problems;
-  el.notifications = notifications;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+): Promise<NavBar> =>
+  mountElement<NavBar>('nav-bar', {
+    logName: 'test.log',
+    logProblems: problems,
+    notifications,
+  });
 
 async function resize(el: NavBar, width: number): Promise<NavBar> {
   notify?.(width);
diff --git a/log-viewer/src/components/__tests__/PaneView.test.ts b/log-viewer/src/components/__tests__/PaneView.test.ts
index c12c7e108..2f210cc4f 100644
--- a/log-viewer/src/components/__tests__/PaneView.test.ts
+++ b/log-viewer/src/components/__tests__/PaneView.test.ts
@@ -6,9 +6,7 @@
 import { beforeAll, describe, expect, it } from '@jest/globals';
 import { html } from 'lit';
 
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-jest.mock('#vscode-elements/vscode-badge.js', () => ({}));
-
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { PaneOrientation, PaneSection, PaneView } from '../PaneView.js';
 import '../PaneView.js';
 
@@ -22,16 +20,15 @@ const sections: PaneSection[] = [
  * Collapse is controlled: the consumer owns the record and feeds it back. Mount
  * with that loop wired, the way the inspector does.
  */
-async function mountSections(
+const mountSections = (
   paneSections: PaneSection[],
   props: Partial<PaneView> = {},
-): Promise<PaneView> {
-  const el = document.createElement('pane-view') as PaneView;
-  Object.assign(el, { orientation: 'vertical', sections: paneSections }, props);
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+): Promise<PaneView> =>
+  mountElement<PaneView>('pane-view', {
+    orientation: 'vertical',
+    sections: paneSections,
+    ...props,
+  });
 
 /** With the collapse loop wired, the way the inspector owns the record. */
 async function mount(orientation: PaneOrientation): Promise<PaneView> {
diff --git a/log-viewer/src/components/__tests__/SectionSkeleton.test.ts b/log-viewer/src/components/__tests__/SectionSkeleton.test.ts
index 42c18f647..94374a53c 100644
--- a/log-viewer/src/components/__tests__/SectionSkeleton.test.ts
+++ b/log-viewer/src/components/__tests__/SectionSkeleton.test.ts
@@ -5,22 +5,17 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { LogStatus } from '../../core/log/logStatus.js';
 import { NO_GOVERNOR_USAGE_TEXT, NO_LOG_TEXT } from '../governorCopy.js';
 import type { SectionSkeleton, SkeletonShape } from '../SectionSkeleton.js';
 import '../SectionSkeleton.js';
 
-async function mount(props: {
+const mount = (props: {
   logStatus?: LogStatus;
   shape?: SkeletonShape;
   fallback?: string;
-}): Promise<SectionSkeleton> {
-  const el = document.createElement('section-skeleton') as SectionSkeleton;
-  Object.assign(el, props);
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+}): Promise<SectionSkeleton> => mountElement<SectionSkeleton>('section-skeleton', props);
 
 /** How many bars each row holds, top to bottom. */
 function rowWidths(el: SectionSkeleton): string[][] {
diff --git a/log-viewer/src/components/__tests__/StackedTimeBar.test.ts b/log-viewer/src/components/__tests__/StackedTimeBar.test.ts
index 45bf28a31..364b30aa7 100644
--- a/log-viewer/src/components/__tests__/StackedTimeBar.test.ts
+++ b/log-viewer/src/components/__tests__/StackedTimeBar.test.ts
@@ -3,25 +3,19 @@
  *
  * @jest-environment jsdom
  */
-import { beforeEach, describe, expect, it } from '@jest/globals';
+import { describe, expect, it } from '@jest/globals';
 
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import '../StackedTimeBar.js';
-import type { StackedSegment } from '../StackedTimeBar.js';
+import type { StackedSegment, StackedTimeBar } from '../StackedTimeBar.js';
 
 const SEGMENTS: StackedSegment[] = [
   { label: 'SOQL', value: 200_000_000, color: 'red' },
   { label: 'DML', value: 100_000_000, color: 'blue' },
 ];
 
-async function mount(segments: StackedSegment[], total = 0, legend = false) {
-  const element = document.createElement('stacked-time-bar');
-  element.segments = segments;
-  element.total = total;
-  element.legend = legend;
-  document.body.append(element);
-  await element.updateComplete;
-  return element;
-}
+const mount = (segments: StackedSegment[], total = 0, legend = false) =>
+  mountElement<StackedTimeBar>('stacked-time-bar', { segments, total, legend });
 
 const widths = (element: Element) =>
   [...(element.shadowRoot?.querySelectorAll('rect') ?? [])].map((rect) =>
@@ -29,10 +23,6 @@ const widths = (element: Element) =>
   );
 
 describe('stacked-time-bar', () => {
-  beforeEach(() => {
-    document.body.replaceChildren();
-  });
-
   it('renders nothing without a length to show', async () => {
     expect((await mount([])).shadowRoot?.querySelector('svg')).toBeNull();
   });
diff --git a/log-viewer/src/components/__tests__/VariablesDetail.test.ts b/log-viewer/src/components/__tests__/VariablesDetail.test.ts
index ac3413599..9ebb92d0f 100644
--- a/log-viewer/src/components/__tests__/VariablesDetail.test.ts
+++ b/log-viewer/src/components/__tests__/VariablesDetail.test.ts
@@ -4,16 +4,15 @@
  * @jest-environment jsdom
  */
 import { describe, expect, it } from '@jest/globals';
-import { parse } from 'apex-log-parser';
 
+import { SETTINGS, indexOf, indexesOf, storeOf } from '../../__tests__/helpers/apexLog.js';
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import { MAX_MARKED_PER_VALUE } from '../../core/log/aggregateVariables.js';
-import { logStoreFor, type LogStore } from '../../core/log/LogStore.js';
+import type { LogStore } from '../../core/log/LogStore.js';
 
-// Avoid the heavy CodeBlock import chain (vscode-elements, soql formatter). The
+// Avoid the heavy CodeBlock import chain (the soql formatter). The
 // raw value it renders is covered by variableValue's own tests.
 jest.mock('../CodeBlock.js', () => ({}));
-// The chevron is a vscode-icon, and its connectedCallback throws under jsdom.
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
 
 const frameReads: { store: unknown; index: unknown }[] = [];
 jest.mock('../../core/log/frameVariables.js', () => {
@@ -32,21 +31,7 @@ jest.mock('../../core/log/frameVariables.js', () => {
 import { STATICS_NOTE, type VariablesDetail } from '../VariablesDetail.js';
 import '../VariablesDetail.js';
 
-const FINEST = '64.0 APEX_CODE,FINEST;APEX_PROFILING,NONE;DB,NONE\n';
-const FINE = '64.0 APEX_CODE,FINE;APEX_PROFILING,NONE;DB,NONE\n';
-
-function logOf(body: string, settings = FINEST): LogStore {
-  return logStoreFor(
-    parse(
-      settings +
-        '09:18:22.6 (100)|EXECUTION_STARTED\n' +
-        '09:18:22.6 (200)|CODE_UNIT_STARTED|[EXTERNAL]|066d0000002m8ij|apex://pkg.Entry\n' +
-        body +
-        '09:18:22.6 (900000)|CODE_UNIT_FINISHED|apex://pkg.Entry\n' +
-        '09:18:22.6 (901000)|EXECUTION_FINISHED\n',
-    ),
-  );
-}
+const logOf = (body: string, settings?: string): LogStore => storeOf(body, settings).store;
 
 const FRAME =
   '09:18:22.6 (1000)|METHOD_ENTRY|[1]|01p|ns.Outer.run()\n' +
@@ -56,21 +41,12 @@ const FRAME =
   '09:18:22.6 (1300)|VARIABLE_ASSIGNMENT|[4]|ns.Cache.hits|{"a":1,"b":2}\n' +
   '09:18:22.6 (1700)|METHOD_EXIT|[1]|ns.Outer.run()\n';
 
-/** The eventIndex of the frame whose log text is `text`. */
-function indexOf(store: LogStore, text: string): number {
-  const found = store.log.eventsById.find((event) => event.text === text);
-  if (!found) {
-    throw new Error(`no event with text ${text}`);
-  }
-  return found.eventIndex;
-}
-
 /** No provider in the test, so the consumed store is assigned straight on. */
 async function mount(store: LogStore, props: Partial<VariablesDetail>): Promise<VariablesDetail> {
-  const el = document.createElement('variables-detail') as VariablesDetail;
-  Object.assign(el, { logStore: store }, props);
-  document.body.appendChild(el);
-  await el.updateComplete;
+  const el = await mountElement<VariablesDetail>('variables-detail', {
+    logStore: store,
+    ...props,
+  });
   // The statics index is built on the first ask, so the first paint is a note.
   await el.updateComplete;
   await new Promise((resolve) => setTimeout(resolve, 0));
@@ -117,14 +93,14 @@ describe('VariablesDetail swapping logs', () => {
   // The wrong read is discarded before it paints, so only the read itself shows it.
   it('does not read the new log through the index of the last one', async () => {
     const first = logOf(FRAME);
-    const el = await mount(first, { eventIndex: indexOf(first, 'ns.Outer.run()') });
+    const el = await mount(first, { eventIndex: indexOf(first.log, 'ns.Outer.run()') });
     expect(rowNames(el)).toContain('total');
     const firstIndex = frameReads.find((read) => read.store === first)?.index;
     expect(firstIndex).toBeDefined();
 
     const second = logOf(FRAME);
     el.logStore = second;
-    el.eventIndex = indexOf(second, 'ns.Outer.run()');
+    el.eventIndex = indexOf(second.log, 'ns.Outer.run()');
     await el.updateComplete;
 
     expect(frameReads.some((read) => read.store === second && read.index === firstIndex)).toBe(
@@ -145,7 +121,7 @@ describe('VariablesDetail read failure', () => {
     });
     const errorSpy = jest.spyOn(console, 'error').mockImplementation(() => {});
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(notes(el)).toContain('Could not read the log for variables.');
     errorSpy.mockRestore();
@@ -158,8 +134,8 @@ describe('VariablesDetail skips the frame read for an aggregate', () => {
   it('never asks for the frame when more than one instance is selected', async () => {
     const store = logOf(FRAME);
     const el = await mount(store, {
-      eventIndex: indexOf(store, 'ns.Outer.run()'),
-      frames: [indexOf(store, 'ns.Outer.run()'), indexOf(store, 'ns.Outer.run()')],
+      eventIndex: indexOf(store.log, 'ns.Outer.run()'),
+      frames: [indexOf(store.log, 'ns.Outer.run()'), indexOf(store.log, 'ns.Outer.run()')],
     });
 
     expect((el as unknown as { _frame: unknown })._frame).toBeNull();
@@ -170,9 +146,9 @@ describe('VariablesDetail empty states', () => {
   // Telling a FINEST user to set FINEST is the worst answer available, so each
   // case has to read differently.
   it('names the log level that would fill it', async () => {
-    const store = logOf(FRAME, FINE);
+    const store = logOf(FRAME, SETTINGS.fine);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(notes(el)).toEqual(['Variables available with the Apex Code log level at FINEST.']);
   });
@@ -180,7 +156,7 @@ describe('VariablesDetail empty states', () => {
   it('says a FINEST log recorded no write at all', async () => {
     const store = logOf('09:18:22.6 (1000)|METHOD_ENTRY|[1]|01p|ns.Outer.run()\n');
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(notes(el)).toEqual(['This log records no variable assignments.']);
   });
@@ -192,7 +168,7 @@ describe('VariablesDetail empty states', () => {
         '09:18:22.6 (1900)|METHOD_EXIT|[9]|ns.Quiet.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Quiet.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Quiet.run()') });
 
     // The statics are still visible from it, so this frame reports them.
     expect(groupNames(el)).toContain('Static');
@@ -237,7 +213,7 @@ describe('VariablesDetail groups', () => {
   it('shows Local, this and Static, in that order', async () => {
     const store = logOf(FRAME);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(groupNames(el)).toEqual(['Local', 'this', 'Static']);
   });
@@ -245,7 +221,7 @@ describe('VariablesDetail groups', () => {
   it('opens Local and leaves the rest closed', async () => {
     const store = logOf(FRAME);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     const groups = treeRows(el).filter((row) => row.querySelector('.group-name'));
     expect(groups.map((row) => row.getAttribute('aria-expanded'))).toEqual([
@@ -261,7 +237,7 @@ describe('VariablesDetail groups', () => {
   it('gives every row that opens a chevron, and every other row its gap', async () => {
     const store = logOf(FRAME);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     for (const row of treeRows(el)) {
       const opens = row.getAttribute('aria-expanded') !== null;
@@ -273,7 +249,7 @@ describe('VariablesDetail groups', () => {
   it('shows the declared type the log recorded', async () => {
     const store = logOf(FRAME);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(rowText(el)).toContain('Integer');
   });
@@ -285,11 +261,11 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1850)|VARIABLE_ASSIGNMENT|[10]|other|7\n' +
         '09:18:22.6 (1900)|METHOD_EXIT|[9]|ns.Second.run()\n',
     );
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     treeRows(el)[0]?.click();
     await el.updateComplete;
-    el.eventIndex = indexOf(store, 'ns.Second.run()');
+    el.eventIndex = indexOf(store.log, 'ns.Second.run()');
     await el.updateComplete;
 
     expect(treeRows(el)[0]?.getAttribute('aria-expanded')).toBe('false');
@@ -299,7 +275,7 @@ describe('VariablesDetail groups', () => {
   it('offers no expander on a value a row can hold', async () => {
     const store = logOf(FRAME);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     // `total` is 42, so its row opens on nothing.
     const total = rowNamed(el, 'total');
@@ -314,7 +290,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1100)|VARIABLE_ASSIGNMENT|[2]|held|{"a":1,"b":2}\n' +
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const held = () => treeRows(el).find((row) => row.dataset.id === 'local/held');
 
     const before = held()?.querySelector('.value')?.textContent?.trim();
@@ -336,7 +312,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(rowText(el)).toContain('not assigned');
   });
@@ -345,7 +321,7 @@ describe('VariablesDetail groups', () => {
   it('joins a name to its value with a colon', async () => {
     const store = logOf(FRAME);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(rowNamed(el, 'total')?.querySelector('.name')?.textContent).toBe('total:');
   });
@@ -358,7 +334,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(rowNamed(el, 'never')?.querySelector('.name')?.textContent).toBe('never');
   });
@@ -372,7 +348,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const alias = rowNamed(el, 'alias');
 
     expect(alias?.querySelector('.missing')?.textContent).toContain('no value recorded');
@@ -392,7 +368,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1600)|METHOD_EXIT|[4]|ns.Outer.after()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const alias = rowNamed(el, 'alias');
 
     expect(alias?.querySelector('.missing')?.textContent).toContain('recorded later');
@@ -415,7 +391,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const writer = rowNamed(el, 'writer');
 
     // The row has no width for the namespace, so the hover carries it whole.
@@ -438,7 +414,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(rowNamed(el, 'writer')?.querySelector('.cls')).toBeNull();
   });
@@ -454,7 +430,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Writer.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Writer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Writer.run()') });
 
     expect(rowNames(el)).not.toContain('this');
     expect(groupNames(el)).toContain('this');
@@ -471,7 +447,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(rowNamed(el, 'payload')?.querySelector('.chip')?.textContent).toBe('json');
   });
@@ -484,7 +460,7 @@ describe('VariablesDetail groups', () => {
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const alias = rowNamed(el, 'alias');
 
     expect(alias?.querySelector('.value')?.textContent).toContain('Id');
@@ -507,7 +483,7 @@ describe('VariablesDetail keyboard', () => {
         '09:18:22.6 (1000)|METHOD_ENTRY|[2]|01p|ns.Outer.run()\n' +
         '09:18:22.6 (1300)|METHOD_EXIT|[2]|ns.Outer.run()\n',
     );
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     // Local starts open with no locals, so it opens onto a note.
     expect(tabStop(el)).toBe('local');
@@ -522,7 +498,7 @@ describe('VariablesDetail keyboard', () => {
   it('gives the tree one tab stop', async () => {
     const store = logOf(FRAME);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(el.shadowRoot?.querySelectorAll('[tabindex="0"]')).toHaveLength(1);
     expect(tabStop(el)).toBe('local');
@@ -530,7 +506,7 @@ describe('VariablesDetail keyboard', () => {
 
   it('walks down and up', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     await press(el, 'ArrowDown');
     const second = tabStop(el);
@@ -542,7 +518,7 @@ describe('VariablesDetail keyboard', () => {
 
   it('opens with the right arrow and closes with the left', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     // Walk to `this`, which starts closed.
     while (tabStop(el) !== 'this') {
@@ -559,7 +535,7 @@ describe('VariablesDetail keyboard', () => {
 
   it('steps out to the row that holds it', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     // Local is open, so the row below it is one of its own.
     await press(el, 'ArrowDown');
@@ -570,7 +546,7 @@ describe('VariablesDetail keyboard', () => {
 
   it('reaches the first and last row', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     await press(el, 'End');
     const last = tabStop(el);
@@ -582,7 +558,7 @@ describe('VariablesDetail keyboard', () => {
 
   it('opens every group at one depth with a star', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     await press(el, '*');
 
@@ -596,7 +572,7 @@ describe('VariablesDetail keyboard', () => {
 
   it('toggles with Enter', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     await press(el, 'Enter');
 
@@ -607,7 +583,7 @@ describe('VariablesDetail keyboard', () => {
 describe('VariablesDetail keyboard, key repeat', () => {
   it('holds a row where a held Enter left it, rather than flapping', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     await press(el, 'Enter');
     await press(el, 'Enter', { repeat: true });
@@ -620,7 +596,7 @@ describe('VariablesDetail keyboard, key repeat', () => {
 
   it('leaves a group closed that a held star would re-open', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const local = () => treeRows(el).find((row) => row.dataset.id === 'local');
 
     // Local starts open, and holds the tab stop, so Enter closes it.
@@ -632,7 +608,7 @@ describe('VariablesDetail keyboard, key repeat', () => {
 
   it('keeps the key consumed on a suppressed repeat', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     const event = await press(el, 'Enter', { repeat: true });
 
@@ -641,7 +617,7 @@ describe('VariablesDetail keyboard, key repeat', () => {
 
   it('walks on every repeat, so holding an arrow scrubs', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     await press(el, 'ArrowDown');
     const second = tabStop(el);
@@ -660,7 +636,7 @@ describe('VariablesDetail reads the scope once per selection', () => {
 
   it('keeps the same reading when a row opens', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const before = held(el);
 
     treeRows(el)[0]?.click();
@@ -679,7 +655,7 @@ describe('VariablesDetail reads the scope once per selection', () => {
   // pay it again: a held arrow key fires ~20 times a second.
   it('keeps the same rows when the tab stop moves', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const before = rows(el);
 
     tree(el).dispatchEvent(new KeyboardEvent('keydown', { key: 'ArrowDown', bubbles: true }));
@@ -691,7 +667,7 @@ describe('VariablesDetail reads the scope once per selection', () => {
 
   it('builds the rows again when a row opens', async () => {
     const store = logOf(FRAME);
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const before = rows(el);
 
     treeRows(el)[0]?.click();
@@ -707,10 +683,10 @@ describe('VariablesDetail reads the scope once per selection', () => {
         '09:18:22.6 (1850)|VARIABLE_ASSIGNMENT|[10]|other|7\n' +
         '09:18:22.6 (1900)|METHOD_EXIT|[9]|ns.Second.run()\n',
     );
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const before = held(el);
 
-    el.eventIndex = indexOf(store, 'ns.Second.run()');
+    el.eventIndex = indexOf(store.log, 'ns.Second.run()');
     await el.updateComplete;
 
     expect(held(el)).not.toBe(before);
@@ -725,7 +701,7 @@ describe('VariablesDetail properties', () => {
         '09:18:22.6 (1100)|VARIABLE_ASSIGNMENT|[2]|outer|{"inner":{"a":1,"b":2},"n":3}\n' +
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const at = (id: string) => treeRows(el).find((r) => r.dataset.id === id);
 
     at('local/outer')?.click();
@@ -746,7 +722,7 @@ describe('VariablesDetail properties', () => {
         '09:18:22.6 (1100)|VARIABLE_ASSIGNMENT|[2]|outer|{"n":3}\n' +
         '09:18:22.6 (1300)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     treeRows(el)
       .find((r) => r.dataset.id === 'local/outer')
@@ -778,7 +754,7 @@ describe('VariablesDetail object fields', () => {
   it('counts the fields beside a value the log wrote as {}', async () => {
     const store = logOf(BUILT);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const holder = rowNamed(el, 'holder');
 
     expect(holder?.querySelector('.count')?.textContent?.trim()).toBe('1');
@@ -789,7 +765,7 @@ describe('VariablesDetail object fields', () => {
   it('previews the recorded fields on the closed row', async () => {
     const store = logOf(BUILT);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const holder = rowNamed(el, 'holder');
 
     expect(holder?.querySelector('.value')?.textContent).toContain('sObj: "Account"');
@@ -806,7 +782,7 @@ describe('VariablesDetail object fields', () => {
         '09:18:22.6 (1040)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const big = rowNamed(el, 'big');
 
     expect(big?.querySelector('.missing')).toBeNull();
@@ -824,7 +800,7 @@ describe('VariablesDetail object fields', () => {
         '09:18:22.6 (1030)|VARIABLE_ASSIGNMENT|[3]|holder|{}|0xddd\n' +
         '09:18:22.6 (1040)|METHOD_EXIT|[1]|ns.Loop.run()\n',
     );
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Loop.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Loop.run()') });
 
     // The field names the object it belongs to, so it may be read but not opened.
     treeRows(el)
@@ -841,7 +817,7 @@ describe('VariablesDetail object fields', () => {
   it('offers nothing to open where the log recorded no fields', async () => {
     const store = logOf(BUILT);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
     const plain = rowNamed(el, 'plain');
 
     expect(plain?.querySelector('.count')).toBeNull();
@@ -866,17 +842,10 @@ describe('VariablesDetail comparing a merged row', () => {
 
   const CALLS = call(1000, 'true') + call(2000, 'false') + call(3000, 'false');
 
-  /** Every frame whose text is `text`: a METHOD_EXIT carries the entry's text. */
-  function framesOf(store: LogStore, text: string): number[] {
-    return store.log.eventsById
-      .filter((event) => event.isParent && event.text === text)
-      .map((event) => event.eventIndex);
-  }
-
   /** The comparison on screen, once its walk has answered. */
   async function compared(body = CALLS): Promise<VariablesDetail> {
     const store = logOf(body);
-    const frames = framesOf(store, 'ns.Svc.run()');
+    const frames = indexesOf(store.log, 'ns.Svc.run()');
     const el = await mount(store, { eventIndex: frames[0]!, frames });
     // The comparison is a walk of its own, after the index it reads through.
     await new Promise((resolve) => setTimeout(resolve, 0));
@@ -945,7 +914,7 @@ describe('VariablesDetail comparing a merged row', () => {
     const el = await compared();
     const values = await valuesOf(el, 'retry');
     const seen = locates(el);
-    const calls = framesOf(el.logStore!, 'ns.Svc.run()');
+    const calls = indexesOf(el.logStore!.log, 'ns.Svc.run()');
 
     values[0]?.dispatchEvent(new MouseEvent('pointerenter', { bubbles: true }));
     values[0]?.dispatchEvent(new MouseEvent('pointerleave', { bubbles: true }));
@@ -961,7 +930,7 @@ describe('VariablesDetail comparing a merged row', () => {
     const el = await compared();
     const values = await valuesOf(el, 'retry');
     const seen = locates(el);
-    const calls = framesOf(el.logStore!, 'ns.Svc.run()');
+    const calls = indexesOf(el.logStore!.log, 'ns.Svc.run()');
 
     values[1]?.dispatchEvent(new MouseEvent('click', { bubbles: true }));
 
@@ -975,7 +944,7 @@ describe('VariablesDetail comparing a merged row', () => {
     const el = await compared();
     await valuesOf(el, 'retry');
     const seen = locates(el);
-    const calls = framesOf(el.logStore!, 'ns.Svc.run()');
+    const calls = indexesOf(el.logStore!.log, 'ns.Svc.run()');
 
     // Opening `retry` left the tab stop on it, so one step down lands on its
     // first value.
@@ -1055,7 +1024,7 @@ describe('VariablesDetail comparing a merged row', () => {
   it('does not say the statics are not compared for a single frame', async () => {
     const store = logOf(FRAME);
 
-    const el = await mount(store, { eventIndex: indexOf(store, 'ns.Outer.run()') });
+    const el = await mount(store, { eventIndex: indexOf(store.log, 'ns.Outer.run()') });
 
     expect(notes(el)).not.toContain(STATICS_NOTE);
   });
@@ -1075,15 +1044,13 @@ describe('VariablesDetail comparing a merged row', () => {
         '09:18:22.6 (1070)|METHOD_EXIT|[3]|ns.Svc.query()\n' +
         '09:18:22.6 (1080)|METHOD_EXIT|[1]|ns.Outer.run()\n',
     );
-    const calls = store.log.eventsById
-      .filter((event) => event.isParent && event.text === 'ns.Svc.query()')
-      .map((event) => event.eventIndex);
+    const calls = indexesOf(store.log, 'ns.Svc.query()');
 
     // What a bottom-up caller row hands over: the calls it counts, and the one
     // frame that made them.
     const el = await mount(store, {
       eventIndex: calls[0]!,
-      frames: [indexOf(store, 'ns.Outer.run()')],
+      frames: [indexOf(store.log, 'ns.Outer.run()')],
     });
 
     expect(rowNames(el)).toContain('outerLocal');
diff --git a/log-viewer/src/components/__tests__/ViewModeSwitch.test.ts b/log-viewer/src/components/__tests__/ViewModeSwitch.test.ts
index d3bad7c70..b2d83b353 100644
--- a/log-viewer/src/components/__tests__/ViewModeSwitch.test.ts
+++ b/log-viewer/src/components/__tests__/ViewModeSwitch.test.ts
@@ -5,10 +5,7 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-// vscode-button needs ElementInternals.setFormValue (absent in jsdom); skip its
-// registration so `<vscode-button>` stays a plain element we can assert on.
-jest.mock('#vscode-elements/vscode-button.js', () => ({}));
-
+import { mountElement } from '../../__tests__/helpers/mount.js';
 import type { ViewModeSwitch } from '../ViewModeSwitch.js';
 import '../ViewModeSwitch.js';
 
@@ -22,14 +19,8 @@ function buttons(el: ViewModeSwitch): HTMLElement[] {
   return Array.from(el.shadowRoot?.querySelectorAll('vscode-button') ?? []) as HTMLElement[];
 }
 
-async function mount(value = 'a'): Promise<ViewModeSwitch> {
-  const el = document.createElement('view-mode-switch') as ViewModeSwitch;
-  el.options = OPTIONS;
-  el.value = value;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (value = 'a'): Promise<ViewModeSwitch> =>
+  mountElement<ViewModeSwitch>('view-mode-switch', { options: OPTIONS, value });
 
 describe('ViewModeSwitch', () => {
   it('renders one button per option and marks the active one non-secondary', async () => {
diff --git a/log-viewer/src/components/__tests__/skeletonStatus.test.ts b/log-viewer/src/components/__tests__/skeletonStatus.test.ts
index 28ef3416d..1d6674a3e 100644
--- a/log-viewer/src/components/__tests__/skeletonStatus.test.ts
+++ b/log-viewer/src/components/__tests__/skeletonStatus.test.ts
@@ -5,10 +5,6 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-// jsdom can't run the real elements (they read document.baseURI / setFormValue).
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-jest.mock('#vscode-elements/vscode-button.js', () => ({}));
-
 import { ContextProvider } from '@lit/context';
 
 import { logStatusContext, type LogStatus } from '../../core/log/logStatus.js';
diff --git a/log-viewer/src/core/log/__tests__/aggregateVariables.test.ts b/log-viewer/src/core/log/__tests__/aggregateVariables.test.ts
index 3bf0b5f79..34bb1f812 100644
--- a/log-viewer/src/core/log/__tests__/aggregateVariables.test.ts
+++ b/log-viewer/src/core/log/__tests__/aggregateVariables.test.ts
@@ -2,7 +2,8 @@
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
 import { describe, expect, it, jest } from '@jest/globals';
-import { type ApexLog, parse } from 'apex-log-parser';
+
+import { indexesOf, storeOf } from '../../../__tests__/helpers/apexLog.js';
 
 import {
   aggregateVariablesFor,
@@ -10,34 +11,11 @@ import {
   MAX_VALUES_PER_NAME,
 } from '../aggregateVariables.js';
 import { variableIndexFor } from '../frameVariables.js';
-import { logStoreFor, type LogStore } from '../LogStore.js';
-
-const SETTINGS = '64.0 APEX_CODE,FINEST;APEX_PROFILING,NONE;DB,NONE\n';
 
 /** Resolves at once, so a test measures the walk rather than the frames it
  *  would leave to the next paint. */
 const yieldSlice = (): Promise<void> => Promise.resolve();
 
-function storeOf(body: string): { log: ApexLog; store: LogStore } {
-  const log = parse(
-    SETTINGS +
-      '09:18:22.6 (100)|EXECUTION_STARTED\n' +
-      '09:18:22.6 (200)|CODE_UNIT_STARTED|[EXTERNAL]|066d0000002m8ij|apex://pkg.Entry\n' +
-      body +
-      '09:18:22.6 (900000)|CODE_UNIT_FINISHED|apex://pkg.Entry\n' +
-      '09:18:22.6 (901000)|EXECUTION_FINISHED\n',
-  );
-  return { log, store: logStoreFor(log) };
-}
-
-/** Every frame whose log text is `text`, in log order. Frames only: a
- *  METHOD_EXIT carries the same text as the entry it closes. */
-function indexesOf(log: ApexLog, text: string): number[] {
-  return log.eventsById
-    .filter((event) => event.isParent && event.text === text)
-    .map((event) => event.eventIndex);
-}
-
 /** One call of `ns.Svc.run()` writing `retry` and `accountId`. */
 function call(at: number, retry: string, accountId: string): string {
   const t = (offset: number): string => `09:18:22.6 (${at + offset})`;
diff --git a/log-viewer/src/core/log/__tests__/frameVariables.test.ts b/log-viewer/src/core/log/__tests__/frameVariables.test.ts
index 5046f7d59..0927eb2e4 100644
--- a/log-viewer/src/core/log/__tests__/frameVariables.test.ts
+++ b/log-viewer/src/core/log/__tests__/frameVariables.test.ts
@@ -2,7 +2,8 @@
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
 import { describe, expect, it } from '@jest/globals';
-import { type ApexLog, parse } from 'apex-log-parser';
+
+import { SETTINGS, indexOf, storeOf } from '../../../__tests__/helpers/apexLog.js';
 
 import {
   apexCodeLevel,
@@ -10,35 +11,6 @@ import {
   recordsVariables,
   variableIndexFor,
 } from '../frameVariables.js';
-import { logStoreFor, type LogStore } from '../LogStore.js';
-
-const SETTINGS = '64.0 APEX_CODE,FINEST;APEX_PROFILING,NONE;DB,NONE\n';
-
-/** Wraps `body` in the header and footer the parser needs to build a tree. */
-function logOf(body: string, settings = SETTINGS): string {
-  return (
-    settings +
-    '09:18:22.6 (100)|EXECUTION_STARTED\n' +
-    '09:18:22.6 (200)|CODE_UNIT_STARTED|[EXTERNAL]|066d0000002m8ij|apex://pkg.Entry\n' +
-    body +
-    '09:18:22.6 (900000)|CODE_UNIT_FINISHED|apex://pkg.Entry\n' +
-    '09:18:22.6 (901000)|EXECUTION_FINISHED\n'
-  );
-}
-
-function storeOf(body: string, settings = SETTINGS): { log: ApexLog; store: LogStore } {
-  const log = parse(logOf(body, settings));
-  return { log, store: logStoreFor(log) };
-}
-
-/** The eventIndex of the frame or event whose log text is `text`. */
-function indexOf(log: ApexLog, text: string): number {
-  const found = log.eventsById.find((event) => event.text === text);
-  if (!found) {
-    throw new Error(`no event with text ${text}`);
-  }
-  return found.eventIndex;
-}
 
 const OUTER =
   '09:18:22.6 (1000)|METHOD_ENTRY|[1]|01p|ns.Outer.run()\n' +
@@ -52,12 +24,14 @@ const OUTER =
 
 describe('apexCodeLevel', () => {
   it('reads the level the log was captured at', () => {
-    expect(apexCodeLevel(storeOf('').log)).toBe('FINEST');
-    expect(recordsVariables(storeOf('').log)).toBe(true);
+    const { log } = storeOf('', SETTINGS.finest);
+
+    expect(apexCodeLevel(log)).toBe('FINEST');
+    expect(recordsVariables(log)).toBe(true);
   });
 
   it('tells a level that records no variables from one that does', () => {
-    const { log } = storeOf('', '64.0 APEX_CODE,FINE;APEX_PROFILING,NONE;DB,NONE\n');
+    const { log } = storeOf('', SETTINGS.fine);
 
     expect(apexCodeLevel(log)).toBe('FINE');
     expect(recordsVariables(log)).toBe(false);
@@ -107,14 +81,13 @@ describe('frameVariablesFor', () => {
     // The inner call sits between the two writes to `total`.
     const atInner = frameVariablesFor(store, indexOf(log, 'ns.Inner.step()'), null);
     const outerIndex = indexOf(log, 'ns.Outer.run()');
-    const inner = log.eventsById.find((event) => event.text === 'ns.Inner.step()')!;
     const fromParent = frameVariablesFor(store, outerIndex, null);
 
     // Asked of the inner frame, the answer is the inner frame's own scope.
     expect(atInner?.frameLabel).toBe('ns.Inner.step()');
     // Asked of the outer frame, both of its writes are in.
     expect(fromParent?.locals[0]?.value).toBe('2');
-    expect(inner.eventIndex).toBeGreaterThan(outerIndex);
+    expect(indexOf(log, 'ns.Inner.step()')).toBeGreaterThan(outerIndex);
   });
 
   it('splits instance fields out of the locals', () => {
diff --git a/log-viewer/src/__tests__/EventSearch.test.ts b/log-viewer/src/core/utility/__tests__/EventSearch.test.ts
similarity index 94%
rename from log-viewer/src/__tests__/EventSearch.test.ts
rename to log-viewer/src/core/utility/__tests__/EventSearch.test.ts
index e371a4b4c..623f558c9 100644
--- a/log-viewer/src/__tests__/EventSearch.test.ts
+++ b/log-viewer/src/core/utility/__tests__/EventSearch.test.ts
@@ -4,7 +4,7 @@
 import { describe, expect, it } from '@jest/globals';
 import { parse } from 'apex-log-parser';
 
-import { findEventByEventIndex } from '../core/utility/EventSearch.js';
+import { findEventByEventIndex } from '../EventSearch.js';
 
 describe('EventSearch', () => {
   it('finds the exact event by eventIndex when timestamps are duplicated', () => {
diff --git a/log-viewer/src/core/utility/__tests__/Util.test.ts b/log-viewer/src/core/utility/__tests__/Util.test.ts
index e9903a640..c03773da8 100644
--- a/log-viewer/src/core/utility/__tests__/Util.test.ts
+++ b/log-viewer/src/core/utility/__tests__/Util.test.ts
@@ -3,61 +3,41 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-import { computeWallClockMs, formatByteSize, formatWallClockTime } from '../Util.js';
+import {
+  computeWallClockMs,
+  formatByteSize,
+  formatDuration,
+  formatWallClockTime,
+} from '../Util.js';
 
 describe('formatWallClockTime', () => {
-  it('should format midnight as 00:00:00.000', () => {
-    expect(formatWallClockTime(0)).toBe('00:00:00.000');
-  });
-
-  it('should format a mid-day time', () => {
-    // 14:30:05.122 = (14*3600 + 30*60 + 5) * 1000 + 122 = 52205122
-    expect(formatWallClockTime(52205122)).toBe('14:30:05.122');
-  });
-
-  it('should format end-of-day time', () => {
-    // 23:59:59.999
-    expect(formatWallClockTime(86399999)).toBe('23:59:59.999');
-  });
-
-  it('should pad single-digit hours, minutes, seconds', () => {
-    // 01:02:03.004
-    expect(formatWallClockTime(3723004)).toBe('01:02:03.004');
-  });
-
-  it('should handle exact seconds (no fractional ms)', () => {
-    // 10:00:00.000
-    expect(formatWallClockTime(36000000)).toBe('10:00:00.000');
-  });
-
-  it('should handle sub-millisecond precision by rounding', () => {
-    // 1000.5 ms → rounds to 1001 ms fraction → 00:00:01.001
-    expect(formatWallClockTime(1000.5)).toBe('00:00:01.001');
+  it.each([
+    ['midnight', 0, '00:00:00.000'],
+    ['a mid-day time', 52205122, '14:30:05.122'],
+    ['the end of the day', 86399999, '23:59:59.999'],
+    ['single-digit hours, minutes and seconds, padded', 3723004, '01:02:03.004'],
+    ['exact seconds, with no fractional ms', 36000000, '10:00:00.000'],
+    ['sub-millisecond precision, rounded up', 1000.5, '00:00:01.001'],
+  ])('formats %s', (_case, ms, expected) => {
+    expect(formatWallClockTime(ms)).toBe(expected);
   });
 });
 
 describe('computeWallClockMs', () => {
-  it('should return startTime when event is the first event', () => {
-    const result = computeWallClockMs(37764600, 6329577, 6329577);
-    expect(result).toBe(37764600);
-  });
+  // The first event: stamped FIRST_NS, on the wall clock at START_MS.
+  const START_MS = 37764600;
+  const FIRST_NS = 6329577;
 
-  it('should compute wall-clock for a later event', () => {
-    // Event is 1ms (1,000,000 ns) after first event
-    const result = computeWallClockMs(37764600, 6329577, 7329577);
-    expect(result).toBe(37764601);
+  it.each([
+    ['the first event itself', FIRST_NS, START_MS],
+    ['an event 1ms later', FIRST_NS + 1_000_000, START_MS + 1],
+    ['an event 1s later', FIRST_NS + 1_000_000_000, START_MS + 1000],
+  ])('reads %s', (_case, timestamp, expected) => {
+    expect(computeWallClockMs(START_MS, FIRST_NS, timestamp)).toBe(expected);
   });
 
-  it('should compute wall-clock for an event 1 second later', () => {
-    // 1 second = 1,000,000,000 ns
-    const result = computeWallClockMs(37764600, 6329577, 1006329577);
-    expect(result).toBe(37765600);
-  });
-
-  it('should handle fractional nanosecond differences', () => {
-    // 500,000 ns = 0.5 ms
-    const result = computeWallClockMs(0, 0, 500000);
-    expect(result).toBe(0.5);
+  it('keeps a fractional millisecond', () => {
+    expect(computeWallClockMs(0, 0, 500000)).toBe(0.5);
   });
 });
 
@@ -80,3 +60,91 @@ describe('formatByteSize', () => {
     expect(formatByteSize(-1_500_000)).toBe('-1.5 MB');
   });
 });
+
+describe('Format duration tests', () => {
+  it('Shows ms with decimals for very small values (sub-millisecond)', () => {
+    expect(formatDuration(5)).toBe('0 ms'); // 0.000005 ms rounds to 0
+    expect(formatDuration(50)).toBe('0 ms'); // 0.00005 ms rounds to 0
+    expect(formatDuration(500)).toBe('0.001 ms');
+    expect(formatDuration(1000)).toBe('0.001 ms');
+    expect(formatDuration(5000)).toBe('0.005 ms');
+    expect(formatDuration(9999)).toBe('0.01 ms');
+    expect(formatDuration(10000)).toBe('0.01 ms');
+    expect(formatDuration(50000)).toBe('0.05 ms');
+    expect(formatDuration(99999)).toBe('0.1 ms');
+  });
+
+  it('handles ms duration', () => {
+    expect(formatDuration(100_000)).toBe('0.1 ms');
+    expect(formatDuration(500_000)).toBe('0.5 ms');
+    expect(formatDuration(1_000_000)).toBe('1 ms');
+    expect(formatDuration(1_234_567)).toBe('1.23 ms');
+    expect(formatDuration(9_999_999)).toBe('10 ms');
+    expect(formatDuration(10_000_000)).toBe('10 ms');
+    expect(formatDuration(99_999_999)).toBe('100 ms');
+    expect(formatDuration(100_000_000)).toBe('100 ms');
+    expect(formatDuration(999_000_000)).toBe('999 ms');
+  });
+
+  it('handles zero duration', () => {
+    expect(formatDuration(0)).toBe('0 ms');
+  });
+
+  it('handles seconds', () => {
+    expect(formatDuration(5_000_000_000)).toBe('5 s');
+    expect(formatDuration(59_500_000_000)).toBe('59.5 s');
+  });
+
+  it('handles minutes and seconds', () => {
+    expect(formatDuration(60_000_000_000)).toBe('1m');
+    expect(formatDuration(125_000_000_000)).toBe('2m 5s');
+    expect(formatDuration(125_500_000_000)).toBe('2m 5.5s');
+  });
+
+  it('handles remove trailing 0 for all units types', () => {
+    expect(formatDuration(5000)).toBe('0.005 ms');
+    expect(formatDuration(100_000)).toBe('0.1 ms');
+    expect(formatDuration(5_000_000_000)).toBe('5 s');
+    expect(formatDuration(60_000_000_000)).toBe('1m');
+  });
+
+  it('handles rounding to appropriate precision', () => {
+    // sub-milliseconds (up to 3 decimal places)
+    expect(formatDuration(1234)).toBe('0.001 ms');
+    expect(formatDuration(9876)).toBe('0.01 ms');
+
+    // milliseconds (up to 2 decimal places)
+    expect(formatDuration(1_234_567)).toBe('1.23 ms');
+    expect(formatDuration(9_876_543)).toBe('9.88 ms');
+
+    // seconds (up to 2 decimal places)
+    expect(formatDuration(1_234_567_890)).toBe('1.23 s');
+    expect(formatDuration(9_876_543_210)).toBe('9.88 s');
+  });
+
+  it('rounds to 1dp for min and s', () => {
+    // minutes with fractional seconds
+    expect(formatDuration(125_670_000_000)).toBe('2m 5.7s');
+  });
+
+  describe('compact option', () => {
+    it('omits spaces for milliseconds', () => {
+      expect(formatDuration(0, { compact: true })).toBe('0ms');
+      expect(formatDuration(50000, { compact: true })).toBe('0.05ms');
+      expect(formatDuration(1_000_000, { compact: true })).toBe('1ms');
+      expect(formatDuration(1_234_567, { compact: true })).toBe('1.23ms');
+      expect(formatDuration(100_000_000, { compact: true })).toBe('100ms');
+    });
+
+    it('omits spaces for seconds', () => {
+      expect(formatDuration(5_000_000_000, { compact: true })).toBe('5s');
+      expect(formatDuration(59_500_000_000, { compact: true })).toBe('59.5s');
+    });
+
+    it('omits spaces for minutes', () => {
+      expect(formatDuration(60_000_000_000, { compact: true })).toBe('1m');
+      expect(formatDuration(125_000_000_000, { compact: true })).toBe('2m5s');
+      expect(formatDuration(125_500_000_000, { compact: true })).toBe('2m5.5s');
+    });
+  });
+});
diff --git a/log-viewer/src/features/analysis/components/__tests__/AnalysisView.test.ts b/log-viewer/src/features/analysis/components/__tests__/AnalysisView.test.ts
index 453398113..82a95f1f4 100644
--- a/log-viewer/src/features/analysis/components/__tests__/AnalysisView.test.ts
+++ b/log-viewer/src/features/analysis/components/__tests__/AnalysisView.test.ts
@@ -29,10 +29,6 @@ jest.mock('../../../call-tree/components/BottomUpTable.js', () => ({
     tableBuilt: new Promise<Tabulator>(() => {}),
   }),
 }));
-// vscode-button needs ElementInternals.setFormValue (absent in jsdom).
-jest.mock('#vscode-elements/vscode-button.js', () => ({}));
-jest.mock('#vscode-elements/vscode-option.js', () => ({}));
-jest.mock('#vscode-elements/vscode-toolbar-button.js', () => ({}));
 
 import {
   eventBus,
diff --git a/log-viewer/src/features/analysis/components/__tests__/LogDiagnosticsView.test.ts b/log-viewer/src/features/analysis/components/__tests__/LogDiagnosticsView.test.ts
index 78ec13ff1..4a8d3230a 100644
--- a/log-viewer/src/features/analysis/components/__tests__/LogDiagnosticsView.test.ts
+++ b/log-viewer/src/features/analysis/components/__tests__/LogDiagnosticsView.test.ts
@@ -5,10 +5,9 @@
  */
 import { beforeEach, describe, expect, it } from '@jest/globals';
 
+import { mountElement } from '../../../../__tests__/helpers/mount.js';
 import type { LogDiagnostics } from '../../services/LogDiagnostics.js';
 
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-
 let result: LogDiagnostics = {
   diagnostics: [],
   queryPlansKnown: true,
@@ -36,12 +35,10 @@ const loadLog = (element: HTMLElementTagNameMap['log-diagnostics']) => {
 };
 
 const view = async (scope?: { instances: number[] }) => {
-  const element = document.createElement('log-diagnostics');
-  if (scope) {
-    element.instances = scope.instances;
-  }
-  document.body.append(element);
-  await element.updateComplete;
+  const element = await mountElement<HTMLElementTagNameMap['log-diagnostics']>(
+    'log-diagnostics',
+    scope ? { instances: scope.instances } : {},
+  );
   // One more turn: the findings arrive from an async call in connectedCallback.
   await element.updateComplete;
   return element;
@@ -65,7 +62,6 @@ const text = (element: HTMLElement, selector: string) =>
 
 describe('log-diagnostics', () => {
   beforeEach(() => {
-    document.body.replaceChildren();
     result = {
       diagnostics: [],
       queryPlansKnown: true,
diff --git a/log-viewer/src/features/analysis/components/__tests__/SelfTimeSpreadView.test.ts b/log-viewer/src/features/analysis/components/__tests__/SelfTimeSpreadView.test.ts
index b1d3b7ed3..27dfbd1bd 100644
--- a/log-viewer/src/features/analysis/components/__tests__/SelfTimeSpreadView.test.ts
+++ b/log-viewer/src/features/analysis/components/__tests__/SelfTimeSpreadView.test.ts
@@ -5,6 +5,7 @@
  */
 import { beforeEach, describe, expect, it } from '@jest/globals';
 
+import { mountElement } from '../../../../__tests__/helpers/mount.js';
 import type { LogStore } from '../../../../core/log/LogStore.js';
 import type { SelfTimeSpread } from '../../services/SelfTimeSpread.js';
 
@@ -39,20 +40,16 @@ const spreadOf = (overrides: Partial<SelfTimeSpread> = {}): SelfTimeSpread => ({
   ...overrides,
 });
 
-const view = async () => {
-  const element = document.createElement('self-time-spread');
-  element.logStore = { log: {} } as unknown as LogStore;
-  document.body.append(element);
-  await element.updateComplete;
-  return element;
-};
+const view = () =>
+  mountElement<HTMLElementTagNameMap['self-time-spread']>('self-time-spread', {
+    logStore: { log: {} } as unknown as LogStore,
+  });
 
 const text = (element: Element, selector: string) =>
   element.shadowRoot!.querySelector(selector)?.textContent?.replace(/\s+/g, ' ').trim();
 
 describe('self-time-spread', () => {
   beforeEach(() => {
-    document.body.replaceChildren();
     spread = null;
   });
 
diff --git a/log-viewer/src/features/analysis/services/__tests__/CallStackSum.test.ts b/log-viewer/src/features/analysis/services/__tests__/CallStackSum.test.ts
index e2c9dab01..2d1d99b0b 100644
--- a/log-viewer/src/features/analysis/services/__tests__/CallStackSum.test.ts
+++ b/log-viewer/src/features/analysis/services/__tests__/CallStackSum.test.ts
@@ -1,8 +1,7 @@
 /**
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
-import { beforeEach, describe, expect, it } from '@jest/globals';
-import type { LogEvent } from 'apex-log-parser';
+import { describe, expect, it } from '@jest/globals';
 
 import {
   sumDurationTotalForRootEvents,
@@ -10,47 +9,9 @@ import {
   sumTotalForRootEvents,
 } from '../CallStackSum.js';
 import type { Metric } from '../RowGrouper.js';
-
-type EventOptions = {
-  text: string;
-  total: number;
-  heapTotal?: number;
-  parent?: LogEvent | null;
-};
-
-let nextTimestamp = 1;
-
-function createEvent(options: EventOptions): LogEvent {
-  const event = {
-    parent: options.parent ?? null,
-    children: [],
-    type: 'METHOD_ENTRY' as LogEvent['type'],
-    text: options.text,
-    namespace: 'default',
-    timestamp: nextTimestamp++,
-    duration: { self: 0, total: options.total },
-    heapAllocated: { self: 0, total: options.heapTotal ?? 0 },
-    dmlRowCount: { self: 0, total: 0 },
-    soqlRowCount: { self: 0, total: 0 },
-    soslRowCount: { self: 0, total: 0 },
-    dmlCount: { self: 0, total: 0 },
-    soqlCount: { self: 0, total: 0 },
-    soslCount: { self: 0, total: 0 },
-    thrownCount: { self: 0, total: 0 },
-  } as unknown as LogEvent;
-
-  if (options.parent) {
-    options.parent.children.push(event);
-  }
-
-  return event;
-}
+import { createEvent } from '../../../../__tests__/helpers/events.js';
 
 describe('sumDurationTotalForRootEvents', () => {
-  beforeEach(() => {
-    nextTimestamp = 1;
-  });
-
   it('counts each call-stack root once and skips events whose ancestors are visible', () => {
     // ParentA(80) → LeafA(80); ParentB(30) → LeafB(30).
     // Naive sum = 80+30+80+30 = 220 (double-counts).
@@ -76,10 +37,6 @@ describe('sumDurationTotalForRootEvents', () => {
 });
 
 describe('sumTotalForRootEvents (generic accessor)', () => {
-  beforeEach(() => {
-    nextTimestamp = 1;
-  });
-
   it('dedups by call stack for an arbitrary field (heap total)', () => {
     // Parent heap 100 (subtree total), its leaf 100; another parent 30, its leaf 30.
     // Naive sum = 260; root-only dedup = 130. Proves the BottomUp heap-total footer
@@ -96,10 +53,6 @@ describe('sumTotalForRootEvents (generic accessor)', () => {
 });
 
 describe('sumRootNodesOnly (Metric adapter)', () => {
-  beforeEach(() => {
-    nextTimestamp = 1;
-  });
-
   it('extracts Metric.nodes and applies the root-only sum', () => {
     const parent = createEvent({ text: 'parent', total: 100 });
     const child = createEvent({ text: 'child', total: 60, parent });
diff --git a/log-viewer/src/features/analysis/services/__tests__/RowGrouper.test.ts b/log-viewer/src/features/analysis/services/__tests__/RowGrouper.test.ts
index 64fb8be64..c60a2588e 100644
--- a/log-viewer/src/features/analysis/services/__tests__/RowGrouper.test.ts
+++ b/log-viewer/src/features/analysis/services/__tests__/RowGrouper.test.ts
@@ -1,74 +1,12 @@
 /**
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
-import { beforeEach, describe, expect, it } from '@jest/globals';
-import type { LogEvent } from 'apex-log-parser';
+import { describe, expect, it } from '@jest/globals';
 
+import { createEvent } from '../../../../__tests__/helpers/events.js';
 import { group } from '../RowGrouper.js';
 
-type EventOptions = {
-  text: string;
-  self: number;
-  total: number;
-  parent?: LogEvent | null;
-  type?: string;
-  namespace?: string;
-  dmlSelf?: number;
-  dmlTotal?: number;
-  soqlSelf?: number;
-  soqlTotal?: number;
-  thrown?: number;
-};
-
-let nextTimestamp = 1;
-
-function createEvent(options: EventOptions): LogEvent {
-  const event = {
-    logParser: null,
-    parent: options.parent ?? null,
-    children: [],
-    type: (options.type ?? 'METHOD_ENTRY') as LogEvent['type'],
-    logLine: '',
-    text: options.text,
-    acceptsText: false,
-    isExit: false,
-    isParent: false,
-    isTruncated: false,
-    nextLineIsExit: false,
-    lineNumber: null,
-    namespace: options.namespace ?? 'default',
-    hasValidSymbols: true,
-    suffix: null,
-    discontinuity: false,
-    timestamp: nextTimestamp++,
-    exitStamp: null,
-    category: '',
-    debugCategory: '',
-    debugLevel: '',
-    cpuType: '',
-    duration: { self: options.self, total: options.total },
-    dmlRowCount: { self: 0, total: 0 },
-    soqlRowCount: { self: 0, total: 0 },
-    soslRowCount: { self: 0, total: 0 },
-    dmlCount: { self: options.dmlSelf ?? 0, total: options.dmlTotal ?? 0 },
-    soqlCount: { self: options.soqlSelf ?? 0, total: options.soqlTotal ?? 0 },
-    soslCount: { self: 0, total: 0 },
-    thrownCount: { self: options.thrown ?? 0, total: options.thrown ?? 0 },
-    exitTypes: [],
-  } as unknown as LogEvent;
-
-  if (options.parent) {
-    options.parent.children.push(event);
-  }
-
-  return event;
-}
-
 describe('RowGrouper.group', () => {
-  beforeEach(() => {
-    nextTimestamp = 1;
-  });
-
   it('includes zero-time leaves so DML/SOQL/exception counts and call counts roll up', () => {
     const root = createEvent({ text: 'LOG_ROOT', self: 0, total: 0, type: 'EXECUTION_STARTED' });
     createEvent({
diff --git a/log-viewer/src/features/app/__tests__/escapeDeselect.test.ts b/log-viewer/src/features/app/__tests__/escapeDeselect.test.ts
index cbc938d12..07482402c 100644
--- a/log-viewer/src/features/app/__tests__/escapeDeselect.test.ts
+++ b/log-viewer/src/features/app/__tests__/escapeDeselect.test.ts
@@ -62,10 +62,6 @@ function toggleFor(panelId: string): HTMLElement {
 }
 
 describe('isDeselectEscape', () => {
-  afterEach(() => {
-    document.body.innerHTML = '';
-  });
-
   it('accepts a plain Escape', () => {
     expect(judge(document.body)).toBe(true);
   });
diff --git a/log-viewer/src/features/app/__tests__/logLoadFailure.test.ts b/log-viewer/src/features/app/__tests__/logLoadFailure.test.ts
index 717ec8fac..8e855f458 100644
--- a/log-viewer/src/features/app/__tests__/logLoadFailure.test.ts
+++ b/log-viewer/src/features/app/__tests__/logLoadFailure.test.ts
@@ -5,11 +5,6 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-// jsdom can't run the real elements (they read document.baseURI).
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-jest.mock('#vscode-elements/vscode-tabs.js', () => ({}));
-jest.mock('#vscode-elements/vscode-tab-header.js', () => ({}));
-jest.mock('#vscode-elements/vscode-tab-panel.js', () => ({}));
 // The header and the inspector pull in every grid, and Tabulator needs a real DOM.
 jest.mock('../AppHeader.js', () => ({}));
 jest.mock('../../../components/LogInspector.js', () => ({}));
@@ -18,6 +13,7 @@ jest.mock('../../../core/messaging/VSCodeExtensionMessenger.js', () => ({
   VSCodeExtensionMessenger: { listen: jest.fn(() => () => {}) },
 }));
 
+import { mountElement } from '../../../__tests__/helpers/mount.js';
 import type { LogViewer } from '../LogViewer.js';
 import '../LogViewer.js';
 
@@ -32,12 +28,7 @@ const MINIMAL_LOG = [
   '12:00:00.1 (100)|EXECUTION_FINISHED',
 ].join('\n');
 
-async function mount(): Promise<LogViewer> {
-  const el = document.createElement('log-viewer') as LogViewer;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (): Promise<LogViewer> => mountElement<LogViewer>('log-viewer');
 
 describe('a log that could not be read', () => {
   it('reports a failed load rather than an empty log', async () => {
diff --git a/log-viewer/src/features/call-tree/utils/__tests__/Aggregation.test.ts b/log-viewer/src/features/call-tree/utils/__tests__/Aggregation.test.ts
index 5100079cd..4d2b7a0ca 100644
--- a/log-viewer/src/features/call-tree/utils/__tests__/Aggregation.test.ts
+++ b/log-viewer/src/features/call-tree/utils/__tests__/Aggregation.test.ts
@@ -1,9 +1,10 @@
 /**
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
-import { beforeEach, describe, expect, it } from '@jest/globals';
+import { describe, expect, it } from '@jest/globals';
 import type { LogEvent } from 'apex-log-parser';
 
+import { createEvent } from '../../../../__tests__/helpers/events.js';
 import { outermostEvents } from '../../../../core/utility/EventTree.js';
 import {
   toAggregatedCallTree,
@@ -13,76 +14,6 @@ import {
 } from '../Aggregation.js';
 import { KeyPathIds } from '../../../../core/log/keyPathIds.js';
 
-type EventOptions = {
-  text: string;
-  self: number;
-  total: number;
-  parent?: LogEvent | null;
-  type?: string;
-  dmlSelf?: number;
-  dmlTotal?: number;
-  soqlSelf?: number;
-  soqlTotal?: number;
-  soslSelf?: number;
-  soslTotal?: number;
-  dmlRowSelf?: number;
-  dmlRowTotal?: number;
-  soqlRowSelf?: number;
-  soqlRowTotal?: number;
-  soslRowSelf?: number;
-  soslRowTotal?: number;
-  thrown?: number;
-  heapSelf?: number;
-  heapTotal?: number;
-};
-
-let nextTimestamp = 1;
-
-function createEvent(options: EventOptions): LogEvent {
-  const event = {
-    logParser: null,
-    parent: options.parent ?? null,
-    children: [],
-    type: (options.type ?? 'METHOD_ENTRY') as LogEvent['type'],
-    logLine: '',
-    text: options.text,
-    acceptsText: false,
-    isExit: false,
-    isParent: false,
-    isTruncated: false,
-    nextLineIsExit: false,
-    lineNumber: null,
-    namespace: 'default',
-    hasValidSymbols: true,
-    suffix: null,
-    discontinuity: false,
-    timestamp: nextTimestamp++,
-    exitStamp: null,
-    category: '',
-    debugCategory: '',
-    debugLevel: '',
-    cpuType: '',
-    duration: { self: options.self, total: options.total },
-    dmlRowCount: { self: options.dmlRowSelf ?? 0, total: options.dmlRowTotal ?? 0 },
-    soqlRowCount: { self: options.soqlRowSelf ?? 0, total: options.soqlRowTotal ?? 0 },
-    soslRowCount: { self: options.soslRowSelf ?? 0, total: options.soslRowTotal ?? 0 },
-    dmlCount: { self: options.dmlSelf ?? 0, total: options.dmlTotal ?? 0 },
-    soqlCount: { self: options.soqlSelf ?? 0, total: options.soqlTotal ?? 0 },
-    soslCount: { self: options.soslSelf ?? 0, total: options.soslTotal ?? 0 },
-    thrownCount: { self: options.thrown ?? 0, total: options.thrown ?? 0 },
-    heapAllocated: { self: options.heapSelf ?? 0, total: options.heapTotal ?? 0 },
-    heapGross: { self: 0, total: 0 },
-    heapPeak: 0,
-    exitTypes: [],
-  } as unknown as LogEvent;
-
-  if (options.parent) {
-    options.parent.children.push(event);
-  }
-
-  return event;
-}
-
 /** A table per build: the fixtures below reuse event indexes for different
  *  frames, so one frame's key must not be read back for another. */
 function bottomUpOf(children: LogEvent[]): BottomUpRow[] {
@@ -200,10 +131,6 @@ function sumTraceSelfTime(events: LogEvent[]): number {
 }
 
 describe('toBottomUpTree', () => {
-  beforeEach(() => {
-    nextTimestamp = 1;
-  });
-
   it('attributes caller rows using the current node contribution, not the caller event metrics', () => {
     const root = createEvent({ text: 'LOG_ROOT', self: 0, total: 0, type: 'EXECUTION_STARTED' });
     const parentA = createEvent({
@@ -1031,10 +958,6 @@ describe('toBottomUpTree', () => {
 });
 
 describe('bottom-up caller row scope', () => {
-  beforeEach(() => {
-    nextTimestamp = 1;
-  });
-
   /** A -> B -> A on one branch, A -> C -> A on the other, so a caller bucket
    *  reaches a strict subset of the root bucket's occurrences. */
   function recursiveRoot(): LogEvent {
@@ -1107,10 +1030,6 @@ describe('bottom-up caller row scope', () => {
 });
 
 describe('toAggregatedCallTree', () => {
-  beforeEach(() => {
-    nextTimestamp = 1;
-  });
-
   it('includes zero-time frames so DML/SOQL/exception counts and callCount roll up', () => {
     const root = createEvent({ text: 'LOG_ROOT', self: 0, total: 0, type: 'EXECUTION_STARTED' });
     createEvent({
@@ -1130,10 +1049,6 @@ describe('toAggregatedCallTree', () => {
 });
 
 describe('_hasDetailsDeep precomputation', () => {
-  beforeEach(() => {
-    nextTimestamp = 1;
-  });
-
   it('aggregated: marks zero-time leaf with no excluded type as not significant', () => {
     const root = createEvent({ text: 'LOG_ROOT', self: 0, total: 0, type: 'EXECUTION_STARTED' });
     createEvent({ text: 'NoTime', self: 0, total: 0, parent: root });
diff --git a/log-viewer/src/features/call-tree/utils/__tests__/eventText.test.ts b/log-viewer/src/features/call-tree/utils/__tests__/eventText.test.ts
index 46865eaff..8d40eb240 100644
--- a/log-viewer/src/features/call-tree/utils/__tests__/eventText.test.ts
+++ b/log-viewer/src/features/call-tree/utils/__tests__/eventText.test.ts
@@ -2,56 +2,11 @@
  * Copyright (c) 2026 Certinia Inc. All rights reserved.
  */
 import { describe, expect, it } from '@jest/globals';
-import type { GovernorLimits, LogEvent } from 'apex-log-parser';
+import type { GovernorLimits } from 'apex-log-parser';
 
+import { createEvent } from '../../../../__tests__/helpers/events.js';
 import { eventLabel, eventName, formatCallStack, formatEventDetails } from '../eventText.js';
 
-type EventOptions = {
-  text: string;
-  type?: string;
-  self?: number;
-  total?: number;
-  exitStamp?: number | null;
-  suffix?: string | null;
-  parent?: LogEvent | null;
-  soqlTotal?: number;
-  soqlSelf?: number;
-  soqlRowTotal?: number;
-  soqlRowSelf?: number;
-  dmlTotal?: number;
-  dmlSelf?: number;
-  soslRowTotal?: number;
-  soslRowSelf?: number;
-};
-
-let nextTimestamp = 1;
-
-function createEvent(options: EventOptions): LogEvent {
-  const event = {
-    parent: options.parent ?? null,
-    children: [],
-    type: (options.type ?? 'METHOD_ENTRY') as LogEvent['type'],
-    text: options.text,
-    suffix: options.suffix ?? null,
-    namespace: 'default',
-    timestamp: nextTimestamp++,
-    exitStamp: options.exitStamp === undefined ? 1000 : options.exitStamp,
-    cpuType: '',
-    duration: { self: options.self ?? 0, total: options.total ?? 0 },
-    dmlRowCount: { self: 0, total: 0 },
-    soqlRowCount: { self: options.soqlRowSelf ?? 0, total: options.soqlRowTotal ?? 0 },
-    soslRowCount: { self: options.soslRowSelf ?? 0, total: options.soslRowTotal ?? 0 },
-    dmlCount: { self: options.dmlSelf ?? 0, total: options.dmlTotal ?? 0 },
-    soqlCount: { self: options.soqlSelf ?? 0, total: options.soqlTotal ?? 0 },
-    soslCount: { self: 0, total: 0 },
-  } as unknown as LogEvent;
-
-  if (options.parent) {
-    options.parent.children.push(event);
-  }
-  return event;
-}
-
 const limits = {
   soqlQueries: { used: 1, limit: 100 },
   queryRows: { used: 300, limit: 50000 },
@@ -110,6 +65,8 @@ describe('formatEventDetails', () => {
       text: 'MyClass.run()',
       total: 5_000_000,
       self: 2_000_000,
+      // The duration is only reported for a frame that exited.
+      exitStamp: 1000,
     });
     expect(formatEventDetails(event)).toBe(
       ['Name: MyClass.run()', 'Type: METHOD_ENTRY', 'Duration: 5 ms (self 2 ms)'].join('\n'),
@@ -126,6 +83,7 @@ describe('formatEventDetails', () => {
       text: 'SELECT Id FROM Account',
       type: 'SOQL_EXECUTE_BEGIN',
       total: 1_000_000,
+      exitStamp: 1000,
       soqlTotal: 1,
       soqlSelf: 1,
       soqlRowTotal: 300,
diff --git a/log-viewer/src/features/database/components/__tests__/DatabaseOverview.test.ts b/log-viewer/src/features/database/components/__tests__/DatabaseOverview.test.ts
index 4f7af333b..5db46afba 100644
--- a/log-viewer/src/features/database/components/__tests__/DatabaseOverview.test.ts
+++ b/log-viewer/src/features/database/components/__tests__/DatabaseOverview.test.ts
@@ -5,8 +5,8 @@
  */
 import { beforeEach, describe, expect, it } from '@jest/globals';
 import type { ApexLog } from 'apex-log-parser';
-import type { LitElement } from 'lit';
 
+import { mountElement } from '../../../../__tests__/helpers/mount.js';
 import type { StackedTimeBar } from '../../../../components/StackedTimeBar.js';
 import type { LogStore } from '../../../../core/log/LogStore.js';
 import type {
@@ -20,8 +20,6 @@ import type {
 const apexLog = { namespaces: ['pkg', 'trigPkg'] } as unknown as ApexLog;
 let overview: DatabaseOverview | null = null;
 
-// jsdom has no stylesheet for the icon element to adopt, so it is left unregistered.
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
 // The tabulator ESM build and its module registrations don't load under jest; the
 // tree's grid is never built here, only its row mapper is exercised.
 jest.mock('tabulator-tables', () => ({
@@ -196,18 +194,12 @@ const namespaceSplit = (): DatabaseBreakdown[] => [
   },
 ];
 
-async function mount<K extends keyof HTMLElementTagNameMap>(
-  tag: K,
-): Promise<HTMLElementTagNameMap[K] & LitElement> {
-  const element = document.createElement(tag);
+const mount = <K extends 'database-concentration' | 'database-namespaces'>(tag: K) =>
   // No provider in the test, so the consumed store is assigned straight on.
-  (element as unknown as { logStore: LogStore }).logStore = {
-    log: apexLog,
-  } as unknown as LogStore;
-  document.body.append(element);
-  await (element as LitElement).updateComplete;
-  return element as HTMLElementTagNameMap[K] & LitElement;
-}
+  // Both elements hold a `logStore`, which a generic tag cannot prove on its own.
+  mountElement<HTMLElementTagNameMap[K]>(tag, {
+    logStore: { log: apexLog } as unknown as LogStore,
+  } as Partial<HTMLElementTagNameMap[K]>);
 
 const texts = (element: Element, selector: string) =>
   [...(element.shadowRoot?.querySelectorAll(selector) ?? [])].map((node) =>
@@ -267,7 +259,6 @@ describe('databaseTreeRows', () => {
 
 describe('database-concentration', () => {
   beforeEach(() => {
-    document.body.replaceChildren();
     overview = null;
   });
 
@@ -390,7 +381,6 @@ describe('database-concentration', () => {
 
 describe('database-namespaces', () => {
   beforeEach(() => {
-    document.body.replaceChildren();
     overview = null;
   });
 
diff --git a/log-viewer/src/features/database/components/__tests__/DatabaseRowBudget.test.ts b/log-viewer/src/features/database/components/__tests__/DatabaseRowBudget.test.ts
index e74f6a1b9..bdd13672c 100644
--- a/log-viewer/src/features/database/components/__tests__/DatabaseRowBudget.test.ts
+++ b/log-viewer/src/features/database/components/__tests__/DatabaseRowBudget.test.ts
@@ -5,8 +5,8 @@
  */
 import { beforeEach, describe, expect, it } from '@jest/globals';
 import type { ApexLog } from 'apex-log-parser';
-import type { LitElement } from 'lit';
 
+import { mountElement } from '../../../../__tests__/helpers/mount.js';
 import type { StackedTimeBar } from '../../../../components/StackedTimeBar.js';
 import type { LogStore } from '../../../../core/log/LogStore.js';
 import type { RowBudget, RowBudgets } from '../../services/rowBudget.js';
@@ -18,8 +18,8 @@ let budgets: RowBudgets;
 jest.mock('../../services/rowBudget.js', () => ({
   rowBudgets: () => budgets,
 }));
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
 
+import type { DatabaseRowBudget } from '../DatabaseRowBudget.js';
 import '../DatabaseRowBudget.js';
 import { settledNote } from '../../../../components/__tests__/sectionTestUtils.js';
 
@@ -67,16 +67,11 @@ const withBudgets = (...changes: Partial<RowBudget>[]): RowBudgets => {
   };
 };
 
-async function mount(): Promise<LitElement> {
-  const element = document.createElement('database-rows');
+const mount = (): Promise<DatabaseRowBudget> =>
   // No provider in the test, so the consumed store is assigned straight on.
-  (element as unknown as { logStore: LogStore }).logStore = {
-    log: apexLog,
-  } as unknown as LogStore;
-  document.body.append(element);
-  await element.updateComplete;
-  return element;
-}
+  mountElement<DatabaseRowBudget>('database-rows', {
+    logStore: { log: apexLog } as unknown as LogStore,
+  });
 
 const texts = (element: Element, selector: string) =>
   [...(element.shadowRoot?.querySelectorAll(selector) ?? [])].map((node) =>
@@ -96,7 +91,6 @@ const barOf = (element: Element, label: string) =>
   bars(element).find((bar) => bar.getAttribute('label') === label);
 
 beforeEach(() => {
-  document.body.replaceChildren();
   budgets = full();
 });
 
diff --git a/log-viewer/src/features/database/components/__tests__/DatabaseView.test.ts b/log-viewer/src/features/database/components/__tests__/DatabaseView.test.ts
index ee8b4f006..bcf9efe47 100644
--- a/log-viewer/src/features/database/components/__tests__/DatabaseView.test.ts
+++ b/log-viewer/src/features/database/components/__tests__/DatabaseView.test.ts
@@ -4,6 +4,7 @@
  * @jest-environment jsdom
  */
 import { afterEach, beforeEach, describe, expect, it } from '@jest/globals';
+import type { LitElement } from 'lit';
 
 import {
   eventBus,
@@ -21,6 +22,7 @@ jest.mock('../GovernorSummary.js', () => ({}));
 jest.mock('../DatabaseSection.js', () => ({}));
 
 import '../DatabaseView.js';
+import { mountElement } from '../../../../__tests__/helpers/mount.js';
 
 /** The slice of a grid DatabaseView drives, standing in for the real element. */
 interface FakeGrid extends HTMLElement {
@@ -49,16 +51,13 @@ function fakeGrid(tag: string, owns: number | null = null): FakeGrid {
 }
 
 describe('database-view selection', () => {
-  let view: HTMLElement;
+  let view: LitElement;
   let grids: Record<StatementType, FakeGrid>;
   let seen: Array<{ source: DetailSource; selection: DetailSelection | null }>;
   let off: () => void;
 
   beforeEach(async () => {
-    document.body.replaceChildren();
-    view = document.createElement('database-view');
-    document.body.append(view);
-    await (view as HTMLElement & { updateComplete: Promise<unknown> }).updateComplete;
+    view = await mountElement<LitElement>('database-view');
     grids = {
       dml: fakeGrid('dml-view'),
       soql: fakeGrid('soql-view', 42),
@@ -71,7 +70,6 @@ describe('database-view selection', () => {
 
   afterEach(() => {
     off();
-    document.body.replaceChildren();
   });
 
   /** The grids report upward; DatabaseView alone turns that into a selection. */
@@ -181,17 +179,10 @@ describe('database-view selection', () => {
 });
 
 describe('database-view find totals', () => {
-  let view: HTMLElement & { updateComplete: Promise<unknown> };
+  let view: LitElement;
 
   beforeEach(async () => {
-    document.body.replaceChildren();
-    view = document.createElement('database-view') as typeof view;
-    document.body.append(view);
-    await view.updateComplete;
-  });
-
-  afterEach(() => {
-    document.body.replaceChildren();
+    view = await mountElement<LitElement>('database-view');
   });
 
   /** The totals DatabaseView rolls up to the find widget while `run` happens. */
diff --git a/log-viewer/src/features/database/components/__tests__/GovernorSummary.test.ts b/log-viewer/src/features/database/components/__tests__/GovernorSummary.test.ts
index e83650103..35d0f1031 100644
--- a/log-viewer/src/features/database/components/__tests__/GovernorSummary.test.ts
+++ b/log-viewer/src/features/database/components/__tests__/GovernorSummary.test.ts
@@ -3,26 +3,23 @@
  *
  * @jest-environment jsdom
  */
-import { beforeEach, describe, expect, it } from '@jest/globals';
+import { describe, expect, it } from '@jest/globals';
 
 import { NO_LIMIT_FOR_METRIC_TEXT } from '../../../../components/governorCopy.js';
 import { formatInteger } from '../../../../core/utility/Util.js';
-import type { GaugeMetric, GovernorSummary } from '../GovernorSummary.js';
+import { mountElement } from '../../../../__tests__/helpers/mount.js';
+import {
+  GOVERNOR_WARN_PERCENT,
+  governorTier,
+  type GaugeMetric,
+  type GovernorSummary,
+} from '../GovernorSummary.js';
 import '../GovernorSummary.js';
 
-const strip = async (metrics: GaugeMetric[]) => {
-  const element = document.createElement('governor-summary') as GovernorSummary;
-  element.metrics = metrics;
-  document.body.append(element);
-  await element.updateComplete;
-  return element;
-};
+const strip = (metrics: GaugeMetric[]) =>
+  mountElement<GovernorSummary>('governor-summary', { metrics });
 
 describe('governor-summary', () => {
-  beforeEach(() => {
-    document.body.replaceChildren();
-  });
-
   describe('a limit the log reported', () => {
     it('meters the value against it', async () => {
       const element = await strip([
@@ -96,21 +93,29 @@ describe('governor-summary', () => {
       return [...classes].find((name) => name.startsWith('gauge__value--')) ?? null;
     };
 
-    it('reads safe below the warn threshold', async () => {
-      expect(await tierOf(79, 100)).toBe('gauge__value--safe');
-    });
-
-    it('warns from the threshold', async () => {
+    it('puts the tier the policy gives on the figure', async () => {
       expect(await tierOf(80, 100)).toBe('gauge__value--warn');
     });
 
-    it('reads danger at the limit', async () => {
-      expect(await tierOf(100, 100)).toBe('gauge__value--danger');
-    });
-
     // No limit, so no tier to report against.
     it('takes none where the log reported no limit', async () => {
       expect(await tierOf(12, 0)).toBeNull();
     });
   });
 });
+
+// The boundaries of the policy its three importers read, stated here and nowhere
+// else. A component proves it applies what it is given, not where the bands fall.
+// DatabaseMetricCard.ts:29 does not import it — it holds a fourth copy, on a bare 80.
+describe('governorTier', () => {
+  it.each([
+    [0, 'safe'],
+    [GOVERNOR_WARN_PERCENT - 0.1, 'safe'],
+    [GOVERNOR_WARN_PERCENT, 'warn'],
+    [99.9, 'warn'],
+    [100, 'danger'],
+    [250, 'danger'],
+  ])('reads %p percent as %s', (percent, expected) => {
+    expect(governorTier(percent)).toBe(expected);
+  });
+});
diff --git a/log-viewer/src/features/notifications/__tests__/IssueList.test.ts b/log-viewer/src/features/notifications/__tests__/IssueList.test.ts
index 47f73cb5d..a5d15211f 100644
--- a/log-viewer/src/features/notifications/__tests__/IssueList.test.ts
+++ b/log-viewer/src/features/notifications/__tests__/IssueList.test.ts
@@ -5,9 +5,7 @@
  */
 import { afterEach, beforeAll, describe, expect, it } from '@jest/globals';
 
-// jsdom can't run the real elements (they read document.baseURI / setFormValue).
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-
+import { mountElement } from '../../../__tests__/helpers/mount.js';
 import type { IssueAction, IssueSeverity, LogIssue } from '../types.js';
 
 import type { IssueList } from '../components/IssueList.js';
@@ -30,13 +28,8 @@ function issue(
   };
 }
 
-async function mount(issues: readonly LogIssue[]): Promise<IssueList> {
-  const el = document.createElement('issue-list') as IssueList;
-  el.issues = issues;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (issues: readonly LogIssue[]): Promise<IssueList> =>
+  mountElement<IssueList>('issue-list', { issues });
 
 function cards(el: IssueList): HTMLElement[] {
   return Array.from(el.shadowRoot?.querySelectorAll<HTMLElement>('.issue') ?? []);
diff --git a/log-viewer/src/features/notifications/__tests__/NotificationCentre.test.ts b/log-viewer/src/features/notifications/__tests__/NotificationCentre.test.ts
index 5496a0f07..8e9a936df 100644
--- a/log-viewer/src/features/notifications/__tests__/NotificationCentre.test.ts
+++ b/log-viewer/src/features/notifications/__tests__/NotificationCentre.test.ts
@@ -5,10 +5,7 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-// jsdom can't run the real elements (they read document.baseURI / setFormValue).
-jest.mock('#vscode-elements/vscode-icon.js', () => ({}));
-jest.mock('#vscode-elements/vscode-button.js', () => ({}));
-
+import { mountElement } from '../../../__tests__/helpers/mount.js';
 import type { IssueSeverity, LogIssue } from '../types.js';
 
 import type { NotificationCentre } from '../components/NotificationCentre.js';
@@ -26,13 +23,8 @@ function issue(severity: IssueSeverity): LogIssue {
   };
 }
 
-async function mount(issues: readonly LogIssue[]): Promise<NotificationCentre> {
-  const el = document.createElement('notification-centre') as NotificationCentre;
-  el.issues = issues;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (issues: readonly LogIssue[]): Promise<NotificationCentre> =>
+  mountElement<NotificationCentre>('notification-centre', { issues });
 
 function badge(el: NotificationCentre): HTMLElement | null {
   return el.shadowRoot?.querySelector('.header-control__badge') ?? null;
diff --git a/log-viewer/src/__tests__/soql/SOQLLinter.test.ts b/log-viewer/src/features/soql/services/__tests__/SOQLLinter.test.ts
similarity index 83%
rename from log-viewer/src/__tests__/soql/SOQLLinter.test.ts
rename to log-viewer/src/features/soql/services/__tests__/SOQLLinter.test.ts
index 90311b9ec..845936e6f 100644
--- a/log-viewer/src/__tests__/soql/SOQLLinter.test.ts
+++ b/log-viewer/src/features/soql/services/__tests__/SOQLLinter.test.ts
@@ -4,7 +4,7 @@
 import { describe, expect, it } from '@jest/globals';
 import { ApexLogParser, LogEvent } from 'apex-log-parser';
 
-import { SOQLLinter } from '../../features/soql/services/SOQLLinter.js';
+import { SOQLLinter } from '../SOQLLinter.js';
 
 class DummySOQLLine extends LogEvent {
   constructor(parser: ApexLogParser, parts: string[]) {
@@ -88,41 +88,13 @@ describe('Negative Filter Operator Rule tests', () => {
     severity: 'Warning',
   };
 
-  it('!= : should return rule', async () => {
-    const soql = "SELECT Id FROM ANOBJECT__c WHERE Name != 'A Name'";
-
-    const results = await new SOQLLinter().lint(soql);
-
-    expect(results).toEqual([negativeFilterRule]);
-  });
-
-  it('<> : should return rule', async () => {
-    const soql = "SELECT Id FROM ANOBJECT__c WHERE Name <> 'A Name'";
-
-    const results = await new SOQLLinter().lint(soql);
-
-    expect(results).toEqual([negativeFilterRule]);
-  });
-
-  it('EXCLUDES : should return rule', async () => {
-    const soql = "SELECT Id FROM ANOBJECT__c WHERE Name EXCLUDES ('A Name')";
-
-    const results = await new SOQLLinter().lint(soql);
-
-    expect(results).toEqual([negativeFilterRule]);
-  });
-
-  it('NOT : should return rule', async () => {
-    const soql = "SELECT Id FROM ANOBJECT__c WHERE NOT Name = 'A Name'";
-
-    const results = await new SOQLLinter().lint(soql);
-
-    expect(results).toEqual([negativeFilterRule]);
-  });
-
-  it('NOT IN : should return rule', async () => {
-    const soql = "SELECT Id FROM ANOBJECT__c WHERE Id NOT IN ('a0000000000aaaa')";
-
+  it.each([
+    "SELECT Id FROM ANOBJECT__c WHERE Name != 'A Name'",
+    "SELECT Id FROM ANOBJECT__c WHERE Name <> 'A Name'",
+    "SELECT Id FROM ANOBJECT__c WHERE Name EXCLUDES ('A Name')",
+    "SELECT Id FROM ANOBJECT__c WHERE NOT Name = 'A Name'",
+    "SELECT Id FROM ANOBJECT__c WHERE Id NOT IN ('a0000000000aaaa')",
+  ])('should return rule for %s', async (soql) => {
     const results = await new SOQLLinter().lint(soql);
 
     expect(results).toEqual([negativeFilterRule]);
diff --git a/log-viewer/src/__tests__/SOQLParser.test.ts b/log-viewer/src/features/soql/services/__tests__/SOQLParser.test.ts
similarity index 96%
rename from log-viewer/src/__tests__/SOQLParser.test.ts
rename to log-viewer/src/features/soql/services/__tests__/SOQLParser.test.ts
index 4455197f7..b291e96ae 100644
--- a/log-viewer/src/__tests__/SOQLParser.test.ts
+++ b/log-viewer/src/features/soql/services/__tests__/SOQLParser.test.ts
@@ -3,7 +3,7 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-import { SOQLParser, SyntaxException } from '../features/soql/services/SOQLParser.js';
+import { SOQLParser, SyntaxException } from '../SOQLParser.js';
 
 describe('Analyse database tests', () => {
   it('throws on unparsable query', async () => {
diff --git a/log-viewer/src/features/timeline/__tests__/TimelineKey.test.ts b/log-viewer/src/features/timeline/__tests__/TimelineKey.test.ts
index 9fb041c3a..b797b77b8 100644
--- a/log-viewer/src/features/timeline/__tests__/TimelineKey.test.ts
+++ b/log-viewer/src/features/timeline/__tests__/TimelineKey.test.ts
@@ -5,19 +5,12 @@
  */
 import { describe, expect, it } from '@jest/globals';
 
-// jsdom can't run the real element (vscode-icon reads document.baseURI).
-jest.mock('../../../components/OverflowList.js', () => ({}));
-
+import { mountElement } from '../../../__tests__/helpers/mount.js';
 import type { TimelineKeyEntry, Timelinekey } from '../components/TimelineKey.js';
 import '../components/TimelineKey.js';
 
-async function mount(entries: TimelineKeyEntry[]): Promise<Timelinekey> {
-  const el = document.createElement('timeline-key') as Timelinekey;
-  el.timelineKeys = entries;
-  document.body.appendChild(el);
-  await el.updateComplete;
-  return el;
-}
+const mount = (entries: TimelineKeyEntry[]): Promise<Timelinekey> =>
+  mountElement<Timelinekey>('timeline-key', { timelineKeys: entries });
 
 function chips(el: Timelinekey): HTMLElement[] {
   return [...(el.shadowRoot?.querySelectorAll<HTMLElement>('.chip') ?? [])];
diff --git a/log-viewer/src/features/timeline/__tests__/event-index.test.ts b/log-viewer/src/features/timeline/__tests__/event-index.test.ts
index 265e70a2b..2dc7f98cf 100644
--- a/log-viewer/src/features/timeline/__tests__/event-index.test.ts
+++ b/log-viewer/src/features/timeline/__tests__/event-index.test.ts
@@ -14,8 +14,8 @@
 import { describe, expect, it } from '@jest/globals';
 import type { LogEvent } from 'apex-log-parser';
 
+import { makeViewport } from '../../../__tests__/helpers/viewport.js';
 import { TimelineEventIndex } from '../optimised/TimelineEventIndex.js';
-import type { ViewportState } from '../types/flamechart.types.js';
 
 describe('TimelineEventIndex', () => {
   /**
@@ -37,23 +37,6 @@ describe('TimelineEventIndex', () => {
     } as unknown as LogEvent;
   }
 
-  /**
-   * Helper to create a simple viewport state
-   */
-  function createViewport(
-    zoom: number = 1,
-    offsetX: number = 0,
-    offsetY: number = 0,
-  ): ViewportState {
-    return {
-      zoom,
-      offsetX,
-      offsetY,
-      displayWidth: 1000,
-      displayHeight: 600,
-    };
-  }
-
   describe('initialization and metadata', () => {
     it('should calculate max depth correctly for flat events', () => {
       const events = [createEvent(0, 100), createEvent(200, 100), createEvent(400, 100)];
@@ -101,7 +84,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(0, 100), createEvent(200, 100), createEvent(400, 100)];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Click at screenX=50 (middle of first event)
       const event = index.findEventAtPosition(50, 300, viewport, 0, false);
@@ -115,7 +98,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(0, 100), createEvent(200, 100), createEvent(400, 100)];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(2, 0, 0); // 2x zoom
+      const viewport = makeViewport({ zoom: 2 }); // 2x zoom
 
       // With 2x zoom, event [0-100] is rendered at [0-200] screen pixels
       const event = index.findEventAtPosition(100, 300, viewport, 0, false);
@@ -129,7 +112,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(0, 100), createEvent(200, 100), createEvent(400, 100)];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 100, 0); // Pan 100px right
+      const viewport = makeViewport({ offsetX: 100 }); // Pan 100px right
 
       // With offsetX=100, event [0-100] is rendered at [-100 to 0]
       // Event [200-300] is rendered at [100-200]
@@ -144,7 +127,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(0, 100), createEvent(200, 100)];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Click at screenX=150 (gap between events)
       const event = index.findEventAtPosition(150, 300, viewport, 0, false);
@@ -156,7 +139,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(100, 100), createEvent(300, 100)];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Click at screenX=50 (before first event)
       const event = index.findEventAtPosition(50, 300, viewport, 0, false);
@@ -168,7 +151,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(0, 100), createEvent(200, 100)];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Click at screenX=500 (after last event)
       const event = index.findEventAtPosition(500, 300, viewport, 0, false);
@@ -181,7 +164,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(0, 0.01)]; // 0.01ns duration
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0); // 1px per ns
+      const viewport = makeViewport(); // 1px per ns
 
       // Event width = 0.01px (below 0.05 threshold)
       const event = index.findEventAtPosition(0, 300, viewport, 0, false);
@@ -194,7 +177,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(0, 0.01)]; // 0.01ns duration
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // With shouldIgnoreWidth=true
       const event = index.findEventAtPosition(0, 300, viewport, 0, true);
@@ -211,7 +194,7 @@ describe('TimelineEventIndex', () => {
       const events = [parent];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Click on parent at depth 0
       const event = index.findEventAtPosition(10, 300, viewport, 0, false);
@@ -226,7 +209,7 @@ describe('TimelineEventIndex', () => {
       const events = [parent];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Click on child at depth 1
       const event = index.findEventAtPosition(60, 300, viewport, 1, false);
@@ -241,7 +224,7 @@ describe('TimelineEventIndex', () => {
       const events = [parent];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Click on child position but search at depth 0 (parent level)
       const event = index.findEventAtPosition(60, 300, viewport, 0, false);
@@ -257,7 +240,7 @@ describe('TimelineEventIndex', () => {
       const events = [level0];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Find event at depth 2
       const event = index.findEventAtPosition(65, 300, viewport, 2, false);
@@ -272,7 +255,7 @@ describe('TimelineEventIndex', () => {
       const events = [parent];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Search at depth 5 (doesn't exist)
       const event = index.findEventAtPosition(60, 300, viewport, 5, false);
@@ -412,7 +395,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(100, 50), createEvent(100, 50), createEvent(100, 50)];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Should find one of them
       const event = index.findEventAtPosition(120, 300, viewport, 0, false);
@@ -425,7 +408,7 @@ describe('TimelineEventIndex', () => {
       const events = [createEvent(100, 0)];
 
       const index = new TimelineEventIndex(events);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = makeViewport();
 
       // Zero-duration event has no width, can't be found normally
       const event = index.findEventAtPosition(100, 300, viewport, 0, false);
diff --git a/log-viewer/src/features/timeline/__tests__/keyboard-handler.test.ts b/log-viewer/src/features/timeline/__tests__/keyboard-handler.test.ts
index eb6cb2bbf..8577e97f8 100644
--- a/log-viewer/src/features/timeline/__tests__/keyboard-handler.test.ts
+++ b/log-viewer/src/features/timeline/__tests__/keyboard-handler.test.ts
@@ -181,34 +181,16 @@ describe('KeyboardHandler', () => {
   });
 
   describe('zoom keys (W / S / + / - / =)', () => {
-    it('should zoom in on W key', () => {
-      dispatchKeyEvent('keydown', 'w');
-
-      expect(callbacks.onZoom).toHaveBeenCalledWith('in');
-    });
-
-    it('should zoom out on S key', () => {
-      dispatchKeyEvent('keydown', 's');
-
-      expect(callbacks.onZoom).toHaveBeenCalledWith('out');
-    });
-
-    it('should zoom in on + key', () => {
-      dispatchKeyEvent('keydown', '+');
-
-      expect(callbacks.onZoom).toHaveBeenCalledWith('in');
-    });
-
-    it('should zoom in on = key', () => {
-      dispatchKeyEvent('keydown', '=');
+    it.each([
+      ['in', 'w'],
+      ['out', 's'],
+      ['in', '+'],
+      ['in', '='],
+      ['out', '-'],
+    ] as const)('should zoom %s on the %s key', (direction, key) => {
+      dispatchKeyEvent('keydown', key);
 
-      expect(callbacks.onZoom).toHaveBeenCalledWith('in');
-    });
-
-    it('should zoom out on - key', () => {
-      dispatchKeyEvent('keydown', '-');
-
-      expect(callbacks.onZoom).toHaveBeenCalledWith('out');
+      expect(callbacks.onZoom).toHaveBeenCalledWith(direction);
     });
 
     it('should zoom with + and - even when Shift is pressed', () => {
@@ -299,37 +281,21 @@ describe('KeyboardHandler', () => {
   });
 
   describe('frame navigation (onFrameNav)', () => {
-    it('should call onFrameNav with "up" on ArrowUp when handler returns true', () => {
-      (callbacks.onFrameNav as jest.Mock).mockReturnValue(true);
-      dispatchKeyEvent('keydown', 'ArrowUp');
-
-      expect(callbacks.onFrameNav).toHaveBeenCalledWith('up');
-      expect(callbacks.onPan).not.toHaveBeenCalled();
-    });
-
-    it('should call onFrameNav with "down" on ArrowDown when handler returns true', () => {
-      (callbacks.onFrameNav as jest.Mock).mockReturnValue(true);
-      dispatchKeyEvent('keydown', 'ArrowDown');
-
-      expect(callbacks.onFrameNav).toHaveBeenCalledWith('down');
-      expect(callbacks.onPan).not.toHaveBeenCalled();
-    });
-
-    it('should call onFrameNav with "left" on ArrowLeft when handler returns true', () => {
-      (callbacks.onFrameNav as jest.Mock).mockReturnValue(true);
-      dispatchKeyEvent('keydown', 'ArrowLeft');
-
-      expect(callbacks.onFrameNav).toHaveBeenCalledWith('left');
-      expect(callbacks.onPan).not.toHaveBeenCalled();
-    });
-
-    it('should call onFrameNav with "right" on ArrowRight when handler returns true', () => {
-      (callbacks.onFrameNav as jest.Mock).mockReturnValue(true);
-      dispatchKeyEvent('keydown', 'ArrowRight');
-
-      expect(callbacks.onFrameNav).toHaveBeenCalledWith('right');
-      expect(callbacks.onPan).not.toHaveBeenCalled();
-    });
+    it.each([
+      ['up', 'ArrowUp'],
+      ['down', 'ArrowDown'],
+      ['left', 'ArrowLeft'],
+      ['right', 'ArrowRight'],
+    ] as const)(
+      'should call onFrameNav with "%s" on %s when handler returns true',
+      (direction, key) => {
+        (callbacks.onFrameNav as jest.Mock).mockReturnValue(true);
+        dispatchKeyEvent('keydown', key);
+
+        expect(callbacks.onFrameNav).toHaveBeenCalledWith(direction);
+        expect(callbacks.onPan).not.toHaveBeenCalled();
+      },
+    );
 
     it('should fall through to pan when onFrameNav returns false', () => {
       (callbacks.onFrameNav as jest.Mock).mockReturnValue(false);
@@ -683,6 +649,7 @@ describe('KeyboardHandler', () => {
       dispatchKeyEvent('keydown', 'Home', { repeat: true });
       dispatchKeyEvent('keydown', 'End');
       dispatchKeyEvent('keydown', 'End', { repeat: true });
+      // 0 and Escape are the same command, so a repeat of either is suppressed.
       dispatchKeyEvent('keydown', '0');
       dispatchKeyEvent('keydown', 'Escape', { repeat: true });
 
diff --git a/log-viewer/src/features/timeline/__tests__/search-highlight.test.ts b/log-viewer/src/features/timeline/__tests__/search-highlight.test.ts
index 5f6eb16d3..6deebc1bb 100644
--- a/log-viewer/src/features/timeline/__tests__/search-highlight.test.ts
+++ b/log-viewer/src/features/timeline/__tests__/search-highlight.test.ts
@@ -16,7 +16,8 @@ import * as PIXI from 'pixi.js';
 
 import type { PrecomputedRect } from '../optimised/RectangleCache.js';
 import { SearchHighlightRenderer } from '../optimised/search/SearchHighlightRenderer.js';
-import type { EventNode, ViewportState } from '../types/flamechart.types.js';
+import { makeViewport } from '../../../__tests__/helpers/viewport.js';
+import type { EventNode } from '../types/flamechart.types.js';
 import type { SearchCursor, SearchMatch } from '../types/search.types.js';
 
 describe('SearchHighlightRenderer', () => {
@@ -144,13 +145,7 @@ describe('SearchHighlightRenderer', () => {
     it('should render overlay and border for current match', () => {
       // Given: event with normal screen width
       const match = createMockMatch(0, 10000, 0);
-      const viewport: ViewportState = {
-        zoom: 0.005, // screenWidth = 10000 * 0.005 = 50px
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.005 }); // screenWidth = 10000 * 0.005 = 50px
 
       // When: rendering highlight
       const cursor = createMockCursor([match], 0);
@@ -167,13 +162,7 @@ describe('SearchHighlightRenderer', () => {
     it('should render for small rectangles', () => {
       // Given: event with small screen width
       const match = createMockMatch(0, 100, 0);
-      const viewport: ViewportState = {
-        zoom: 0.002, // screenWidth = 100 * 0.002 = 0.2px
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.002 }); // screenWidth = 100 * 0.002 = 0.2px
 
       // When: rendering
       const cursor = createMockCursor([match], 0);
@@ -186,13 +175,7 @@ describe('SearchHighlightRenderer', () => {
     it('should render for large rectangles', () => {
       // Given: event with large screen width
       const match = createMockMatch(0, 40000, 0);
-      const viewport: ViewportState = {
-        zoom: 0.005, // screenWidth = 40000 * 0.005 = 200px
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.005 }); // screenWidth = 40000 * 0.005 = 200px
 
       // When: rendering
       const cursor = createMockCursor([match], 0);
@@ -206,13 +189,7 @@ describe('SearchHighlightRenderer', () => {
   describe('edge cases', () => {
     it('should handle event at timestamp zero', () => {
       const match = createMockMatch(0, 100, 0);
-      const viewport: ViewportState = {
-        zoom: 0.001, // screenWidth = 0.1px
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.001 }); // screenWidth = 0.1px
 
       // Should not throw and should render
       const cursor = createMockCursor([match], 0);
@@ -222,13 +199,7 @@ describe('SearchHighlightRenderer', () => {
 
     it('should handle very large duration events', () => {
       const match = createMockMatch(0, 1_000_000, 0); // 1ms
-      const viewport: ViewportState = {
-        zoom: 0.005, // screenWidth = 5000px
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.005 }); // screenWidth = 5000px
 
       const cursor = createMockCursor([match], 0);
       expect(() => renderer.render(cursor, viewport)).not.toThrow();
@@ -237,13 +208,7 @@ describe('SearchHighlightRenderer', () => {
 
     it('should handle negative offset (panned left)', () => {
       const match = createMockMatch(500, 100, 0);
-      const viewport: ViewportState = {
-        zoom: 0.001,
-        offsetX: -100, // Panned left
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.001, offsetX: -100 }); // Panned left
 
       const cursor = createMockCursor([match], 0);
       expect(() => renderer.render(cursor, viewport)).not.toThrow();
@@ -252,13 +217,8 @@ describe('SearchHighlightRenderer', () => {
     it('should not render when match is outside viewport', () => {
       // Event far off-screen to the right
       const match = createMockMatch(1_000_000, 100, 0);
-      const viewport: ViewportState = {
-        zoom: 0.001,
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      // The cull is `timestamp >= displayWidth / zoom`, so both numbers decide this one.
+      const viewport = makeViewport({ zoom: 0.001, displayWidth: 1000 });
 
       const cursor = createMockCursor([match], 0);
       renderer.render(cursor, viewport);
@@ -269,13 +229,7 @@ describe('SearchHighlightRenderer', () => {
 
     it('should not render when currentIndex is invalid', () => {
       const match = createMockMatch(0, 100, 0);
-      const viewport: ViewportState = {
-        zoom: 0.005,
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.005 });
 
       // Invalid index (-1)
       const invalidCursor1 = createMockCursor([match], -1);
@@ -291,13 +245,7 @@ describe('SearchHighlightRenderer', () => {
     });
 
     it('should handle empty matches array', () => {
-      const viewport: ViewportState = {
-        zoom: 0.005,
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.005 });
 
       const emptyCursor = createMockCursor([], 0);
       expect(() => renderer.render(emptyCursor, viewport)).not.toThrow();
@@ -308,13 +256,7 @@ describe('SearchHighlightRenderer', () => {
   describe('multiple render calls', () => {
     it('should clear graphics before each render', () => {
       const match = createMockMatch(0, 100, 0);
-      const viewport: ViewportState = {
-        zoom: 0.005,
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.005 });
 
       // First render
       const cursor = createMockCursor([match], 0);
@@ -332,13 +274,7 @@ describe('SearchHighlightRenderer', () => {
     });
 
     it('should handle undefined cursor', () => {
-      const viewport: ViewportState = {
-        zoom: 0.005,
-        offsetX: 0,
-        offsetY: 0,
-        displayWidth: 1000,
-        displayHeight: 600,
-      };
+      const viewport = makeViewport({ zoom: 0.005 });
 
       expect(() => renderer.render(undefined, viewport)).not.toThrow();
       expect(mockGraphics.rect).not.toHaveBeenCalled();
diff --git a/log-viewer/src/features/timeline/__tests__/timeline-dispose.test.ts b/log-viewer/src/features/timeline/__tests__/timeline-dispose.test.ts
index 43260b4ab..070e61f8a 100644
--- a/log-viewer/src/features/timeline/__tests__/timeline-dispose.test.ts
+++ b/log-viewer/src/features/timeline/__tests__/timeline-dispose.test.ts
@@ -41,7 +41,6 @@ describe('legacy timeline listener lifetime', () => {
     dispose();
     added.mockRestore();
     removed.mockRestore();
-    document.body.replaceChildren();
   });
 
   it('listens for the find events once the chart is built', () => {
diff --git a/log-viewer/src/features/timeline/optimised/__tests__/FlameChartResize.test.ts b/log-viewer/src/features/timeline/optimised/__tests__/FlameChartResize.test.ts
index c0e77fc96..7d19f968b 100644
--- a/log-viewer/src/features/timeline/optimised/__tests__/FlameChartResize.test.ts
+++ b/log-viewer/src/features/timeline/optimised/__tests__/FlameChartResize.test.ts
@@ -13,9 +13,11 @@
  */
 
 import { afterEach, describe, expect, it, jest } from '@jest/globals';
+import { internalsOf, stubChartInternals } from '../../../../__tests__/helpers/flameChart.js';
+import { makeViewport } from '../../../../__tests__/helpers/viewport.js';
 import { FlameChart } from '../FlameChart.js';
 
-/** The private collaborators `resize` and `render` need, and nothing else. */
+/** The shared stub, plus the app and viewport handles this suite asserts on. */
 function stubbedChart(displayHeight = 300): {
   chart: FlameChart;
   rendererResize: jest.Mock;
@@ -25,46 +27,19 @@ function stubbedChart(displayHeight = 300): {
   const rendererResize = jest.fn();
   const appRender = jest.fn();
 
-  const internals = chart as unknown as Record<string, unknown>;
+  const internals = stubChartInternals(chart);
   internals['app'] = {
     renderer: { resize: rendererResize },
     screen: { height: 300 },
     render: appRender,
   };
-  internals['container'] = document.createElement('div');
-  internals['index'] = { maxDepth: 1 };
-  internals['worldContainer'] = { position: { set: jest.fn() } };
-  internals['batchRenderer'] = { render: jest.fn(), clear: jest.fn() };
-  internals['rectangleManager'] = {
-    getCulledRectangles: () => ({ visibleRects: new Map(), buckets: new Map() }),
-  };
   internals['viewport'] = {
-    getState: () => ({
-      zoom: 1,
-      offsetX: 0,
-      offsetY: 0,
-      displayWidth: 400,
-      displayHeight,
-    }),
+    getState: () => makeViewport({ displayWidth: 400, displayHeight }),
     setStateForResize: jest.fn(),
   };
   // The geometry init applied: 364 container - 60 minimap - 4 gap = the 300 below.
   internals['appliedMinimapHeight'] = 60;
   internals['appliedOverheadHeight'] = 64;
-  internals['state'] = {
-    viewport: null,
-    needsRender: false,
-    batchColorsCache: new Map(),
-    renderDirty: {
-      background: false,
-      culling: false,
-      eventRendering: false,
-      highlights: false,
-      overlays: false,
-      minimap: false,
-      metricStrip: false,
-    },
-  };
 
   return { chart, rendererResize, appRender };
 }
@@ -124,7 +99,7 @@ describe('FlameChart.resize', () => {
   // so every value the guard used to compare was unchanged while the overhead moved by 19.
   it('draws when the overhead moved but the main timeline height did not', () => {
     const { chart, appRender } = stubbedChart();
-    const internals = chart as unknown as Record<string, unknown>;
+    const internals = internalsOf(chart);
     internals['metricStripOrchestrator'] = {
       getIsVisible: () => true,
       getHeight: () => 15,
@@ -157,7 +132,7 @@ describe('FlameChart.resize', () => {
   // is still owed, or the chart stays blank with nothing left to fill it.
   it('books the dropped frame again when it cannot draw after all', () => {
     const { chart, appRender } = stubbedChart();
-    const internals = chart as unknown as Record<string, unknown>;
+    const internals = internalsOf(chart);
     // No rectangleManager, so `canRender` fails and `render` bails.
     internals['rectangleManager'] = null;
     (internals['state'] as { needsRender: boolean }).needsRender = true;
@@ -172,12 +147,12 @@ describe('FlameChart.resize', () => {
   it('drops a render already queued, rather than painting twice', () => {
     const { chart, appRender } = stubbedChart();
     const cancel = jest.spyOn(window, 'cancelAnimationFrame').mockImplementation(() => {});
-    (chart as unknown as Record<string, unknown>)['renderLoopId'] = 7;
+    internalsOf(chart)['renderLoopId'] = 7;
 
     chart.resize(500, 400);
 
     expect(cancel).toHaveBeenCalledWith(7);
     expect(appRender).toHaveBeenCalledTimes(1);
-    expect((chart as unknown as Record<string, number | null>)['renderLoopId']).toBeNull();
+    expect(internalsOf(chart)['renderLoopId']).toBeNull();
   });
 });
diff --git a/log-viewer/src/features/timeline/optimised/__tests__/HighlightHalo.test.ts b/log-viewer/src/features/timeline/optimised/__tests__/HighlightHalo.test.ts
index d1529f547..839fe637c 100644
--- a/log-viewer/src/features/timeline/optimised/__tests__/HighlightHalo.test.ts
+++ b/log-viewer/src/features/timeline/optimised/__tests__/HighlightHalo.test.ts
@@ -14,20 +14,15 @@
 
 import { describe, expect, it } from '@jest/globals';
 import { Graphics } from 'pixi.js';
-import { TIMELINE_CONSTANTS, type ViewportState } from '../../types/flamechart.types.js';
+import { makeViewport } from '../../../../__tests__/helpers/viewport.js';
+import { TIMELINE_CONSTANTS } from '../../types/flamechart.types.js';
 import {
   createHighlightColors,
   MIN_HIGHLIGHT_WIDTH,
   renderHighlight,
 } from '../rendering/HighlightRenderer.js';
 
-const viewport: ViewportState = {
-  zoom: 1,
-  offsetX: 0,
-  offsetY: 0,
-  displayWidth: 800,
-  displayHeight: 300,
-} as ViewportState;
+const viewport = makeViewport({ displayWidth: 800, displayHeight: 300 });
 
 /** The colours the graphics was told to stroke with, in order: the halo, then the border. */
 function strokeColors(graphics: Graphics): number[] {
diff --git a/log-viewer/src/features/timeline/optimised/__tests__/HoverRehit.test.ts b/log-viewer/src/features/timeline/optimised/__tests__/HoverRehit.test.ts
index 983274cac..94ecc5aea 100644
--- a/log-viewer/src/features/timeline/optimised/__tests__/HoverRehit.test.ts
+++ b/log-viewer/src/features/timeline/optimised/__tests__/HoverRehit.test.ts
@@ -14,49 +14,31 @@
  */
 
 import { describe, expect, it, jest } from '@jest/globals';
+import { internalsOf, stubChartInternals } from '../../../../__tests__/helpers/flameChart.js';
+import { makeViewport } from '../../../../__tests__/helpers/viewport.js';
 import { FlameChart } from '../FlameChart.js';
 
 const HIT_NODE = { id: '0-0', timestamp: 0, duration: 10, depth: 0, original: { eventIndex: 1 } };
 
-/** The private collaborators one `render()` needs to reach the wash, and nothing else. */
+/** The shared stub, plus the hit-test and wash handles this suite asserts on. */
 function stubbedChart(): { chart: FlameChart; hoverRender: jest.Mock; hitTest: jest.Mock } {
   const chart = new FlameChart();
   const hoverRender = jest.fn();
   const hitTest = jest.fn(() => ({ eventNode: HIT_NODE, marker: null }));
 
-  const internals = chart as unknown as Record<string, unknown>;
+  // Culling dirty: the re-hit this is about happens inside the cull the render then does.
+  const internals = stubChartInternals(chart, { culling: true });
   internals['app'] = {
     renderer: { resize: jest.fn() },
     screen: { height: 300 },
     render: jest.fn(),
   };
-  internals['container'] = document.createElement('div');
-  internals['index'] = { maxDepth: 1 };
-  internals['worldContainer'] = { position: { set: jest.fn() } };
-  internals['batchRenderer'] = { render: jest.fn(), clear: jest.fn() };
-  internals['rectangleManager'] = {
-    getCulledRectangles: () => ({ visibleRects: new Map(), buckets: new Map() }),
-  };
   internals['hitDetector'] = { setVisibleRects: jest.fn(), setBuckets: jest.fn(), hitTest };
   internals['hoverHighlightRenderer'] = { render: hoverRender };
   internals['viewport'] = {
-    getState: () => ({ zoom: 1, offsetX: 0, offsetY: 0, displayWidth: 400, displayHeight: 300 }),
+    getState: () => makeViewport({ displayWidth: 400, displayHeight: 300 }),
     screenYToDepth: () => 0,
   };
-  internals['state'] = {
-    viewport: null,
-    needsRender: false,
-    batchColorsCache: new Map(),
-    renderDirty: {
-      background: false,
-      culling: true,
-      eventRendering: false,
-      highlights: false,
-      overlays: false,
-      minimap: false,
-      metricStrip: false,
-    },
-  };
 
   return { chart, hoverRender, hitTest };
 }
@@ -64,7 +46,7 @@ function stubbedChart(): { chart: FlameChart; hoverRender: jest.Mock; hitTest: j
 describe('the hover wash after the frames move', () => {
   it('washes the frame now under the pointer, in the render that moved it', () => {
     const { chart, hoverRender } = stubbedChart();
-    const internals = chart as unknown as Record<string, unknown>;
+    const internals = internalsOf(chart);
     const tracker = internals['hoverTracker'] as {
       setPointer: (x: number, y: number) => void;
       invalidateHit: () => void;
@@ -83,7 +65,7 @@ describe('the hover wash after the frames move', () => {
   // doing. A panel put on a frame by find or by the keyboard reads that and stays put.
   it('reports a re-hit as the frames moving, not as a pointer move', () => {
     const { chart } = stubbedChart();
-    const internals = chart as unknown as Record<string, unknown>;
+    const internals = internalsOf(chart);
     const onMouseMove = jest.fn();
     internals['callbacks'] = { onMouseMove };
     const tracker = internals['hoverTracker'] as {
@@ -102,7 +84,7 @@ describe('the hover wash after the frames move', () => {
   // and a tooltip churning through frames as they slide past, are both noise.
   it('washes nothing while a drag owns the pointer, and asks once it ends', () => {
     const { chart, hitTest, hoverRender } = stubbedChart();
-    const internals = chart as unknown as Record<string, unknown>;
+    const internals = internalsOf(chart);
     let dragging = true;
     internals['interactionHandler'] = {
       isPointerDragging: () => dragging,
@@ -137,7 +119,7 @@ describe('the hover wash after the frames move', () => {
   // Culling is what moves the frames, so a render that reuses it leaves the answer standing.
   it('does not ask again on a render that reuses the culled frames', () => {
     const { chart, hitTest } = stubbedChart();
-    const internals = chart as unknown as Record<string, unknown>;
+    const internals = internalsOf(chart);
     (internals['hoverTracker'] as { setPointer: (x: number, y: number) => void }).setPointer(
       40,
       10,
diff --git a/log-viewer/src/features/timeline/optimised/__tests__/HoverWash.test.ts b/log-viewer/src/features/timeline/optimised/__tests__/HoverWash.test.ts
index 9296dd928..8eeefe24b 100644
--- a/log-viewer/src/features/timeline/optimised/__tests__/HoverWash.test.ts
+++ b/log-viewer/src/features/timeline/optimised/__tests__/HoverWash.test.ts
@@ -13,20 +13,15 @@
 
 import { describe, expect, it } from '@jest/globals';
 import { Graphics } from 'pixi.js';
-import { TIMELINE_CONSTANTS, type ViewportState } from '../../types/flamechart.types.js';
+import { makeViewport } from '../../../../__tests__/helpers/viewport.js';
+import { TIMELINE_CONSTANTS } from '../../types/flamechart.types.js';
 import {
   createHighlightColors,
   renderHighlight,
   renderWash,
 } from '../rendering/HighlightRenderer.js';
 
-const viewport: ViewportState = {
-  zoom: 1,
-  offsetX: 0,
-  offsetY: 0,
-  displayWidth: 800,
-  displayHeight: 300,
-} as ViewportState;
+const viewport = makeViewport({ displayWidth: 800, displayHeight: 300 });
 
 /** The actions the graphics recorded, in order. */
 function actions(graphics: Graphics): string[] {
diff --git a/log-viewer/src/features/timeline/optimised/__tests__/RectangleCache.bucket.test.ts b/log-viewer/src/features/timeline/optimised/__tests__/RectangleCache.bucket.test.ts
index 3dc578acd..a02fcf029 100644
--- a/log-viewer/src/features/timeline/optimised/__tests__/RectangleCache.bucket.test.ts
+++ b/log-viewer/src/features/timeline/optimised/__tests__/RectangleCache.bucket.test.ts
@@ -4,6 +4,7 @@
 import { describe, expect, it } from '@jest/globals';
 import type { LogCategory, LogEvent } from 'apex-log-parser';
 
+import { makeViewport } from '../../../../__tests__/helpers/viewport.js';
 import type { ViewportState } from '../../types/flamechart.types.js';
 import { TIMELINE_CONSTANTS } from '../../types/flamechart.types.js';
 import { legacyCullRectangles } from '../LegacyViewportCuller.js';
@@ -38,21 +39,9 @@ function createEvent(
   } as unknown as LogEvent;
 }
 
-// Helper to create viewport state
-function createViewport(
-  zoom = 1,
-  offsetX = 0,
-  offsetY = 0,
-  displayWidth = 1000,
-  displayHeight = 500,
-): ViewportState {
-  return {
-    zoom,
-    offsetX,
-    offsetY,
-    displayWidth,
-    displayHeight,
-  };
+/** The 1000x500 canvas both culling oracles measure against. */
+function createViewport(over: Partial<ViewportState> = {}): ViewportState {
+  return makeViewport({ displayHeight: 500, ...over });
 }
 
 // Helper to cull rectangles using the legacy O(n) algorithm
@@ -99,7 +88,7 @@ describe('Legacy bucket aggregation', () => {
     it('should return events > 2px in visibleRects', () => {
       // Event with duration 3ns at zoom=1 gives 3px width (> MIN_RECT_SIZE)
       const events = [createEvent(0, 3, 'Apex')];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       expect(result.visibleRects.get('Apex')).toHaveLength(1);
@@ -111,7 +100,7 @@ describe('Legacy bucket aggregation', () => {
     it('should aggregate events <= 2px into buckets', () => {
       // Event with duration 1ns at zoom=1 gives 1px width (<= MIN_RECT_SIZE)
       const events = [createEvent(0, 1, 'Apex')];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       // No visible rects (event is too small), so category has no entry
@@ -128,7 +117,7 @@ describe('Legacy bucket aggregation', () => {
         createEvent(20, 3, 'SOQL'), // 3px at zoom=1 - visible
         createEvent(30, 0.5, 'SOQL'), // 0.5px at zoom=1 - bucketed
       ];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       expect(result.visibleRects.get('Apex')).toHaveLength(1);
@@ -142,7 +131,7 @@ describe('Legacy bucket aggregation', () => {
     it('should create time-aligned bucket boundaries', () => {
       // At zoom=1, bucket width is 2ns (2px / 1)
       const events = [createEvent(5, 1, 'Apex')]; // Event at timestamp 5
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       const allBuckets = getAllBuckets(result.buckets);
@@ -158,7 +147,7 @@ describe('Legacy bucket aggregation', () => {
     it('should group events in same time bucket together', () => {
       // Two events at timestamps 4 and 5 should be in same bucket (index 2, range [4,6))
       const events = [createEvent(4, 1, 'Apex'), createEvent(5, 1, 'Apex')];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       const allBuckets = getAllBuckets(result.buckets);
@@ -173,7 +162,7 @@ describe('Legacy bucket aggregation', () => {
         createEvent(0, 1, 'Apex'), // bucket index 0
         createEvent(10, 1, 'Apex'), // bucket index 5
       ];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       expect(countBuckets(result.buckets)).toBe(2);
@@ -186,7 +175,7 @@ describe('Legacy bucket aggregation', () => {
       const child = createEvent(0, 1, 'SOQL');
       const parent = createEvent(0, 1, 'Apex', [child]);
       const events = [parent];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       // Should have 2 buckets (one per depth)
@@ -199,7 +188,7 @@ describe('Legacy bucket aggregation', () => {
 
     it('should set correct Y position based on depth', () => {
       const events = [createEvent(0, 1, 'Apex')];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       const allBuckets = getAllBuckets(result.buckets);
@@ -211,7 +200,7 @@ describe('Legacy bucket aggregation', () => {
       const events2 = [parent];
 
       // At zoom=0.5, parent (2ns) becomes 1px (bucketed), child (1ns) becomes 0.5px (bucketed)
-      const viewport2 = createViewport(0.5, 0, 0);
+      const viewport2 = createViewport({ zoom: 0.5 });
       const result2 = cullRectanglesLegacy(events2, categories, viewport2);
 
       const allBuckets2 = getAllBuckets(result2.buckets);
@@ -227,7 +216,7 @@ describe('Legacy bucket aggregation', () => {
         createEvent(1, 1, 'SOQL'),
         createEvent(0.5, 1, 'Apex'),
       ];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       // All 3 events at zoom=1 with duration 1ns are < 2px, so all bucketed
@@ -242,7 +231,7 @@ describe('Legacy bucket aggregation', () => {
 
     it('should track total duration per category', () => {
       const events = [createEvent(0, 1, 'Apex'), createEvent(0.5, 0.5, 'Apex')];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       const allBuckets = getAllBuckets(result.buckets);
@@ -254,7 +243,7 @@ describe('Legacy bucket aggregation', () => {
   describe('bucket color resolution', () => {
     it('should prioritize DML over Method in mixed bucket', () => {
       const events = [createEvent(0, 1, 'Apex'), createEvent(0.5, 1, 'DML')];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       // Get bucket from DML category (dominant)
@@ -267,7 +256,7 @@ describe('Legacy bucket aggregation', () => {
 
     it('should prioritize SOQL over Method in mixed bucket', () => {
       const events = [createEvent(0, 1, 'Apex'), createEvent(0.5, 1, 'SOQL')];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       // Get bucket from SOQL category (dominant)
@@ -279,7 +268,7 @@ describe('Legacy bucket aggregation', () => {
   describe('bucket color blending', () => {
     it('should have a valid color for single event', () => {
       const events = [createEvent(0, 1, 'Apex')];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       // Color should be a valid numeric color value (pre-blended opaque)
@@ -294,7 +283,7 @@ describe('Legacy bucket aggregation', () => {
 
       // Create a bucket with a single event
       const singleEvent = [createEvent(0, 1, 'Apex')];
-      const singleViewport = createViewport(1, 0, 0);
+      const singleViewport = createViewport();
       const singleResult = cullRectanglesLegacy(singleEvent, categories, singleViewport);
       const singleBuckets = getAllBuckets(singleResult.buckets);
       const singleBucketColor = singleBuckets[0]!.color;
@@ -304,7 +293,7 @@ describe('Legacy bucket aggregation', () => {
       for (let i = 0; i < 50; i++) {
         manyEvents.push(createEvent(i * 0.03, 0.01, 'Apex')); // All in bucket index 0
       }
-      const manyViewport = createViewport(1, 0, 0);
+      const manyViewport = createViewport();
       const manyResult = cullRectanglesLegacy(manyEvents, categories, manyViewport);
       const manyBuckets = getAllBuckets(manyResult.buckets);
       const manyBucketColor = manyBuckets[0]!.color;
@@ -319,7 +308,7 @@ describe('Legacy bucket aggregation', () => {
       const event1 = createEvent(0, 1, 'Apex');
       const event2 = createEvent(0.5, 1, 'Apex');
       const events = [event1, event2];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       const allBuckets = getAllBuckets(result.buckets);
@@ -336,7 +325,7 @@ describe('Legacy bucket aggregation', () => {
         createEvent(10, 1, 'Apex'), // bucketed
         createEvent(20, 1, 'SOQL'), // bucketed
       ];
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       expect(result.stats.visibleCount).toBe(1);
@@ -350,7 +339,7 @@ describe('Legacy bucket aggregation', () => {
       for (let i = 0; i < 5; i++) {
         events.push(createEvent(i * 0.3, 0.1, 'Apex'));
       }
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = cullRectanglesLegacy(events, categories, viewport);
 
       expect(result.stats.maxEventsPerBucket).toBe(5);
diff --git a/log-viewer/src/features/timeline/optimised/__tests__/TemporalSegmentTree.test.ts b/log-viewer/src/features/timeline/optimised/__tests__/TemporalSegmentTree.test.ts
index 592df6087..a811d0649 100644
--- a/log-viewer/src/features/timeline/optimised/__tests__/TemporalSegmentTree.test.ts
+++ b/log-viewer/src/features/timeline/optimised/__tests__/TemporalSegmentTree.test.ts
@@ -4,6 +4,7 @@
 import { describe, expect, it } from '@jest/globals';
 import type { LogCategory, LogEvent } from 'apex-log-parser';
 
+import { makeViewport } from '../../../../__tests__/helpers/viewport.js';
 import type { PixelBucket, ViewportState } from '../../types/flamechart.types.js';
 import { TIMELINE_CONSTANTS } from '../../types/flamechart.types.js';
 import type { BatchColorInfo } from '../BucketColorResolver.js';
@@ -39,21 +40,9 @@ function createEvent(
   } as unknown as LogEvent;
 }
 
-// Helper to create viewport state
-function createViewport(
-  zoom = 1,
-  offsetX = 0,
-  offsetY = 0,
-  displayWidth = 1000,
-  displayHeight = 500,
-): ViewportState {
-  return {
-    zoom,
-    offsetX,
-    offsetY,
-    displayWidth,
-    displayHeight,
-  };
+/** The 1000x500 canvas both culling oracles measure against. */
+function createViewport(over: Partial<ViewportState> = {}): ViewportState {
+  return makeViewport({ displayHeight: 500, ...over });
 }
 
 // Helper to flatten buckets Map into array for testing
@@ -124,7 +113,7 @@ describe('TemporalSegmentTree', () => {
       const manager = new RectangleCache(events, categories);
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       expect(result.visibleRects.get('Apex')).toHaveLength(1);
@@ -138,7 +127,7 @@ describe('TemporalSegmentTree', () => {
       const manager = new RectangleCache(events, categories);
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       // Pre-initialized map has empty arrays for known categories
@@ -157,7 +146,7 @@ describe('TemporalSegmentTree', () => {
       const manager = new RectangleCache(events, categories);
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
-      const viewport = createViewport(0.1, 0, 0);
+      const viewport = createViewport({ zoom: 0.1 });
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       // All events should be bucketed at this zoom level
@@ -177,11 +166,11 @@ describe('TemporalSegmentTree', () => {
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
       // Zoomed out: all events are small
-      const zoomedOut = createViewport(0.1, 0, 0, 1000);
+      const zoomedOut = createViewport({ zoom: 0.1 });
       const resultOut = tree.query(zoomedOut, EMPTY_BATCH_COLORS);
 
       // Zoomed in: all events are visible
-      const zoomedIn = createViewport(2, 0, 0, 1000);
+      const zoomedIn = createViewport({ zoom: 2 });
       const resultIn = tree.query(zoomedIn, EMPTY_BATCH_COLORS);
 
       // More visible rects when zoomed in
@@ -197,9 +186,9 @@ describe('TemporalSegmentTree', () => {
       const manager = new RectangleCache(events, categories);
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
-      const zoomed1 = createViewport(0.1, 0, 0, 1000);
-      const zoomed2 = createViewport(1, 0, 0, 1000);
-      const zoomed3 = createViewport(10, 0, 0, 1000);
+      const zoomed1 = createViewport({ zoom: 0.1 });
+      const zoomed2 = createViewport();
+      const zoomed3 = createViewport({ zoom: 10 });
 
       const result1 = tree.query(zoomed1, EMPTY_BATCH_COLORS);
       const result2 = tree.query(zoomed2, EMPTY_BATCH_COLORS);
@@ -227,7 +216,7 @@ describe('TemporalSegmentTree', () => {
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
       // Viewport only shows time 50-150 (should only include second event)
-      const viewport = createViewport(1, 50, 0, 100);
+      const viewport = createViewport({ offsetX: 50, displayWidth: 100 });
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       // Only the middle event should be visible
@@ -246,23 +235,15 @@ describe('TemporalSegmentTree', () => {
       // offsetY = 0, height = 2 rows (30px)
       // worldYBottom = 0, worldYTop = 30
       // depthStart = 0, depthEnd = 2
-      const viewportSmall = createViewport(
-        1,
-        0,
-        0,
-        1000,
-        TIMELINE_CONSTANTS.EVENT_HEIGHT * 2, // shows depths 0-1
-      );
+      const viewportSmall = createViewport({
+        displayHeight: TIMELINE_CONSTANTS.EVENT_HEIGHT * 2, // shows depths 0-1
+      });
       const resultSmall = tree.query(viewportSmall, EMPTY_BATCH_COLORS);
 
       // Create a larger viewport that shows all 3 depths
-      const viewportLarge = createViewport(
-        1,
-        0,
-        0,
-        1000,
-        TIMELINE_CONSTANTS.EVENT_HEIGHT * 4, // shows depths 0-3
-      );
+      const viewportLarge = createViewport({
+        displayHeight: TIMELINE_CONSTANTS.EVENT_HEIGHT * 4, // shows depths 0-3
+      });
       const resultLarge = tree.query(viewportLarge, EMPTY_BATCH_COLORS);
 
       // Smaller viewport should have fewer or equal events
@@ -280,7 +261,7 @@ describe('TemporalSegmentTree', () => {
       const manager = new RectangleCache(events, categories);
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       const allBuckets = getAllBuckets(result.buckets);
@@ -299,7 +280,7 @@ describe('TemporalSegmentTree', () => {
       const manager = new RectangleCache(events, categories);
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
-      const viewport = createViewport(0.5, 0, 0); // threshold = 4ns
+      const viewport = createViewport({ zoom: 0.5 }); // threshold = 4ns
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       // All events should be in buckets with correct count
@@ -311,7 +292,7 @@ describe('TemporalSegmentTree', () => {
       const manager = new RectangleCache(events, categories);
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
-      const viewport = createViewport(0.1, 0, 0); // threshold = 20ns
+      const viewport = createViewport({ zoom: 0.1 }); // threshold = 20ns
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       // Bucket should have stats for both categories
@@ -334,7 +315,7 @@ describe('TemporalSegmentTree', () => {
       // Both implementations now use segment tree (legacy is in LegacyViewportCuller)
       // This test verifies the manager produces consistent results
       const manager = new RectangleCache(events, categories);
-      const viewport = createViewport(1, 0, 0);
+      const viewport = createViewport();
       const result = manager.getCulledRectangles(viewport, EMPTY_BATCH_COLORS);
 
       // For comparison with legacy, use the legacy culler directly
@@ -369,7 +350,7 @@ describe('TemporalSegmentTree', () => {
       // Query time range that only intersects with the long event (not the short one)
       // Using viewport that shows time [70, 90]
       // At zoom=1, offset=70, width=20: timeStart=70, timeEnd=90
-      const viewport = createViewport(1, 70, 0, 20, 500);
+      const viewport = createViewport({ offsetX: 70, displayWidth: 20 });
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       // The long event (Method) should be visible because it spans [0, 100]
@@ -391,7 +372,7 @@ describe('TemporalSegmentTree', () => {
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
       // Query time range [80, 120] - only overlaps with the SOQL event (timeEnd=110)
-      const viewport = createViewport(1, 80, 0, 40, 500);
+      const viewport = createViewport({ offsetX: 80, displayWidth: 40 });
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       const totalEvents = result.stats.visibleCount + result.stats.bucketedEventCount;
@@ -423,7 +404,7 @@ describe('TemporalSegmentTree', () => {
       const manager = new RectangleCache(events, categories);
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
-      const viewport = createViewport(0.1, 0, 0); // threshold = 20ns, event = 1ns
+      const viewport = createViewport({ zoom: 0.1 }); // threshold = 20ns, event = 1ns
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       const allBuckets = getAllBuckets(result.buckets);
@@ -438,7 +419,7 @@ describe('TemporalSegmentTree', () => {
       const manager = new RectangleCache(events, categories);
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
-      const viewport = createViewport(1, 0, 0); // threshold = 2ns, event = 1ns
+      const viewport = createViewport(); // threshold = 2ns, event = 1ns
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       const allBuckets = getAllBuckets(result.buckets);
@@ -460,7 +441,7 @@ describe('TemporalSegmentTree', () => {
       const tree = new TemporalSegmentTree(manager.getRectsByCategory());
 
       // Zoom out so all events aggregate into one bucket
-      const viewport = createViewport(0.01, 0, 0, 1000);
+      const viewport = createViewport({ zoom: 0.01 });
       const result = tree.query(viewport, EMPTY_BATCH_COLORS);
 
       // Bucket should be categorized as DML (priority 0 beats priority 1)
diff --git a/log-viewer/src/features/timeline/optimised/metric-strip/MetricStripTooltipRenderer.test.ts b/log-viewer/src/features/timeline/optimised/metric-strip/MetricStripTooltipRenderer.test.ts
index 6dd09446a..5a77fb4dd 100644
--- a/log-viewer/src/features/timeline/optimised/metric-strip/MetricStripTooltipRenderer.test.ts
+++ b/log-viewer/src/features/timeline/optimised/metric-strip/MetricStripTooltipRenderer.test.ts
@@ -12,6 +12,7 @@ import type {
   MetricStripClassifiedMetric,
   MetricStripDataPoint,
 } from '../../types/flamechart.types.js';
+import { waitForNextFrame } from '../../../../core/utility/FrameBudget.js';
 import { PERCENT_COLORS } from '../rendering/tooltip-utils.js';
 import { MetricStripTooltipRenderer } from './MetricStripTooltipRenderer.js';
 
@@ -63,9 +64,7 @@ describe('MetricStripTooltipRenderer', () => {
   }
 
   /** Placement is batched into a frame, so it has to be let through. */
-  function flushFrame(): Promise<void> {
-    return new Promise((resolve) => requestAnimationFrame(() => resolve()));
-  }
+  const flushFrame = waitForNextFrame;
 
   /** One always-show metric, enough to get a row on the panel. */
   const oneMetric = [metric('cpuTime', 'CPU Time', 0.9)];
diff --git a/package.json b/package.json
index d7d9f072c..23fd6008c 100644
--- a/package.json
+++ b/package.json
@@ -47,7 +47,7 @@
     "typecheck": "tsc -b && tsc -p scripts/tsconfig.json",
     "typecheck:tsc6": "tsc6 -b",
     "measure": "rolldown -c scripts/measure/rolldown.config.ts && node --expose-gc --max-old-space-size=12288 scripts/measure/out/measure.mjs",
-    "lint": "concurrently -r -g 'eslint . --cache --cache-location node_modules/.cache/eslint/' 'prettier --cache **/*.{ts,css,md,mdx,scss} --check --experimental-cli' 'pnpm run typecheck'",
+    "lint": "concurrently -r -g 'eslint . --cache --cache-location node_modules/.cache/eslint/' 'prettier --cache \"**/*.{ts,css,md,mdx,scss}\" --check --experimental-cli' 'pnpm run typecheck'",
     "test": "jest",
     "test:ci": "jest --runInBand",
     "test:e2e:web": "pnpm build && playwright test --config=lana/test/playwright/playwright.config.web.ts",