refactor(investigations): drop the lane table and the fan-out columns

[Makisuo]

Stack 4 of 4 — based on the web PR. Drops what the fan-out stored.

What changes

• investigation_lens_runs is dropped, along with investigations.fanout_*, plan_json, planner_*, validator_* and workflow_instance_id (migration 0058_drop_investigation_lanes, which also removes the lane table from the Electric publication).
• InvestigationDocument and the v2 Investigation resource lose lens_runs, validator and fanout. Both were documented as evolving shapes; nothing in the web app or the iOS app reads them after the previous PR.
• InvestigationService no longer loads lanes; the stale sweep has one 15-minute budget; the pass count is the run count; the diagnosis writers drop the fan-out bookkeeping.
• The Electric proxy drops the lane shape and the fan-out columns from the investigation shape.

Deploy note

Prod migrations are applied by hand. 0058 drops a table and ten columns; nothing reads them after PRs 1–3 are deployed, so apply it after those are live.

Verified

Typechecks on packages/domain, packages/backend, apps/api, apps/ai, apps/web, apps/electric-sync; vitest for the migration journal (the idempotent-replay test now replays 0035 at its own point in history), the investigation service and enqueue paths, the electric shapes, the v2 investigation routes and the web collection mapper. db:generate reports no further schema changes.

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Summary by CodeRabbit

• Changes
  • Investigation results and API responses no longer include lens-run, validator, or fan-out metadata.
  • Investigation processing now follows a single diagnosis path without fan-out lanes or related workflow tracking.
  • Stale investigations use one 15-minute timeout, regardless of workflow state.
  • Usage limits count one pass per investigation.
  • Database synchronization now scopes investigation data by investigation ID and no longer syncs separate lens-run records.
  • A database migration removes legacy investigation workflow fields and lens-run storage.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: ca78f48f-57d5-404d-a305-d8056e82b978

📥 Commits

Reviewing files that changed from the base of the PR and between f9cbff8 and 36916e9.

📒 Files selected for processing (26)

• apps/api/src/routes/v2/investigations.http.ts
• apps/api/src/routes/v2/phase1-resources.http.test.ts
• apps/electric-sync/src/electric/ElectricClient.test.ts
• apps/electric-sync/src/shapes/registry.test.ts
• apps/electric-sync/src/shapes/registry.ts
• apps/electric-sync/src/shapes/request.test.ts
• apps/web/src/components/investigations/flow/provenance-canvas.test.tsx
• apps/web/src/components/investigations/flow/provenance-graph.test.ts
• apps/web/src/lib/collections/investigations.test.ts
• apps/web/src/lib/collections/investigations.ts
• packages/backend/src/services/errors/AiTriageService.test.ts
• packages/backend/src/services/errors/InvestigationService.test.ts
• packages/backend/src/services/errors/InvestigationService.ts
• packages/backend/src/services/errors/ai-triage-enqueue.test.ts
• packages/backend/src/services/errors/ai-triage-enqueue.ts
• packages/backend/src/services/errors/apply-diagnosis.ts
• packages/backend/src/services/errors/investigation-quota.ts
• packages/backend/src/services/errors/investigation-stale.ts
• packages/backend/src/services/org/OrganizationService.ts
• packages/db/drizzle/0058_drop_investigation_lanes.sql
• packages/db/drizzle/meta/0058_snapshot.json
• packages/db/drizzle/meta/_journal.json
• packages/db/src/migrations.test.ts
• packages/db/src/schema/investigations.ts
• packages/domain/src/http/investigations.ts
• packages/domain/src/http/v2/investigations.ts

💤 Files with no reviewable changes (9)

• apps/web/src/components/investigations/flow/provenance-graph.test.ts
• packages/backend/src/services/errors/ai-triage-enqueue.test.ts
• packages/backend/src/services/org/OrganizationService.ts
• apps/web/src/lib/collections/investigations.test.ts
• apps/api/src/routes/v2/investigations.http.ts
• apps/web/src/components/investigations/flow/provenance-canvas.test.tsx
• apps/api/src/routes/v2/phase1-resources.http.test.ts
• apps/web/src/lib/collections/investigations.ts
• packages/domain/src/http/v2/investigations.ts

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📝 Walkthrough

Walkthrough

The change removes fan-out and lens-run data from investigation contracts, database persistence, backend processing, Electric synchronization, API responses, and web mappings. Stale handling and quota accounting now use single-investigation rules.

Changes

Single-Agent Investigation Model

Layer / File(s)	Summary
Investigation contracts and API shape packages/domain/src/http/investigations.ts, packages/domain/src/http/v2/investigations.ts, apps/api/src/routes/v2/investigations.http.ts, apps/api/src/routes/v2/phase1-resources.http.test.ts	Domain and V2 API models no longer define or serialize lens_runs, validator, or fanout. API fixtures match the reduced response shape.
Investigation persistence removal packages/db/src/schema/investigations.ts, packages/db/drizzle/0058_drop_investigation_lanes.sql, packages/db/drizzle/meta/_journal.json, packages/db/src/migrations.test.ts, packages/backend/src/services/org/OrganizationService.ts	The schema and migration remove fan-out columns and the investigation_lens_runs table. Migration and organization cleanup no longer treat the table as active.
Backend single-agent flow packages/backend/src/services/errors/InvestigationService.ts, packages/backend/src/services/errors/investigation-stale.ts, packages/backend/src/services/errors/ai-triage-enqueue.ts, packages/backend/src/services/errors/apply-diagnosis.ts, packages/backend/src/services/errors/investigation-quota.ts, packages/backend/src/services/errors/*test.ts	Investigation mapping, restart handling, diagnosis writes, stale detection, and quota usage no longer use fan-out state or lens-run rows. Stale detection uses one 15-minute budget, and each investigation counts as one pass.
Electric synchronization shapes apps/electric-sync/src/shapes/registry.ts, apps/electric-sync/src/shapes/request.test.ts, apps/electric-sync/src/shapes/registry.test.ts, apps/electric-sync/src/electric/ElectricClient.test.ts	Electric synchronization keeps the scoped investigation shape, removes fan-out columns, and removes the investigation_lens_runs shape. Tests verify the updated scope and projection.
Web investigation mapping and fixtures apps/web/src/lib/collections/investigations.ts, apps/web/src/lib/collections/investigations.test.ts, apps/web/src/components/investigations/flow/*test.*	The web row schema, mapped investigation object, and provenance fixtures no longer include fan-out, validator, or lens-run fields.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~60 minutes

Change: Refactor

Merge Risk: ⚪ Minimal · up to 36916

The single-agent investigation model is consistently reflected across the provided contracts, persistence, backend flow, and synchronization shapes. No actionable issue remains before merge.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main changes: removing the investigation lane table and fan-out columns.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch inv/04-drop-lane-schema

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