diff --git a/.dockerignore b/.dockerignore
index 44021c6..f2f978d 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -11,4 +11,8 @@ uploads
 .env.*
 !.env.example
 test
-docs
+
+# docs/ is NOT ignored: the board serves it at /docs, rendering the same
+# markdown files the repository keeps. Excluding it builds an image whose
+# documentation pages all 404 while the index quietly renders its "deployed
+# without its docs directory" fallback — a failure that looks like nothing.
diff --git a/apps/server/src/routes/docs.ts b/apps/server/src/routes/docs.ts
index 2871fee..e75f279 100644
--- a/apps/server/src/routes/docs.ts
+++ b/apps/server/src/routes/docs.ts
@@ -1,4 +1,4 @@
-import { readFileSync, statSync } from 'node:fs';
+import { existsSync, readFileSync, statSync } from 'node:fs';
 import { dirname, join, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { Hono } from 'hono';
@@ -180,6 +180,21 @@ function load(doc: Doc): Rendered | null {
 export function docsRoutes(services: Services) {
   const app = new Hono<AppEnv>();
 
+  /*
+   * Say so at boot if the documents are not in the image.
+   *
+   * They ship as files, so a build that excludes them — one line in
+   * .dockerignore did exactly this — leaves every /docs page answering 404
+   * while the index renders its "no documentation" fallback perfectly happily.
+   * That is a failure with no symptom anybody would notice from the outside,
+   * which is precisely the kind worth a line in the log.
+   */
+  if (!existsSync(DOCS_DIR)) {
+    console.warn(
+      `[tsbb] no docs directory at ${DOCS_DIR} — /docs will be empty. Is it excluded from the build?`,
+    );
+  }
+
   app.get('/docs', async (c) => {
     const entries = DOCS.map((doc) => ({ doc, rendered: load(doc) })).filter(
       (entry): entry is { doc: Doc; rendered: Rendered } => entry.rendered !== null,
diff --git a/test/docs.test.ts b/test/docs.test.ts
index 0a5e1a5..ae4c857 100644
--- a/test/docs.test.ts
+++ b/test/docs.test.ts
@@ -113,6 +113,31 @@ describe('the documentation pages', () => {
     assert.equal(missing.status, 404);
   });
 
+  /*
+   * These pages passed every test above and still 404'd in production, because
+   * .dockerignore excluded docs/ and the deployed image had no files to render.
+   * Nothing that boots the app in a checkout can catch that — the guard has to
+   * be on the thing that was wrong, which is the build configuration.
+   */
+  it('ships the documents in the image', async () => {
+    const { readFileSync } = await import('node:fs');
+    const { dirname, join } = await import('node:path');
+    const { fileURLToPath } = await import('node:url');
+    const root = join(dirname(fileURLToPath(import.meta.url)), '..');
+
+    const ignored = readFileSync(join(root, '.dockerignore'), 'utf8')
+      .split('\n')
+      .map((line) => line.trim())
+      .filter((line) => line && !line.startsWith('#'));
+
+    for (const pattern of ['docs', 'docs/', '/docs', './docs']) {
+      assert.ok(
+        !ignored.includes(pattern),
+        `.dockerignore excludes ${pattern}, so the built image would serve no documentation`,
+      );
+    }
+  });
+
   it('points at the docs from the API index, for a human who found the JSON', async () => {
     const response = await app.fetch(new Request('http://localhost:3993/api/v1'));
     const index = (await response.json()) as { docs: string };