chore(coach): publish the trail route, list it among the mixed reads, and ship its strings in every locale

src/app/api/__tests__/ai-route-inventory.ts

@@ -102,6 +102,11 @@ export const AI_ROUTES: Readonly<Record<string, AiRouteEntry>> = {
     capabilities: ["coach"],
     why: "POST streams a Coach reply from a model. The history GET in the same file asks nothing.",
   },
+  "src/app/api/insights/chat/[id]/messages/[messageId]/trail/route.ts": {
+    kind: "mixed",
+    capabilities: ["coach"],
+    why: "The trail's reasoning text is model-written and served only while the Coach's text may be shown; otherwise 200 with trail null and the ai state.",
+  },
   "src/app/api/insights/generate/route.ts": {
     kind: "action",
     capabilities: ["briefing"],

src/lib/ai/coach/stream-events.ts

@@ -21,7 +21,7 @@ import {
 import {
   PLAN_REVIEW_DAYS,
   REMEMBER_FACT_MAX_CHARS,
-} from "@/lib/ai/coach/memory/contract";
+} from "@/lib/ai/coach/memory/shared";
 import {
   SUGGESTED_ACTION_TYPES,
   type CheckupIntervalId,

src/lib/openapi/routes/coach.ts

@@ -44,6 +44,7 @@ import {
   coachProvenanceSchema,
   coachResultEntrySchema,
   coachStreamEventSchema,
+  coachTrailSchema,
 } from "@/lib/ai/coach/stream-events";
 import {
   coachAttachmentCreateSchema,
@@ -870,6 +871,54 @@ export const coachPaths: NonNullable<ZodOpenApiObject["paths"]> = {
       },
     },
   },
+  "/api/insights/chat/{id}/messages/{messageId}/trail": {
+    get: {
+      tags: ["Insights"],
+      summary: "Read the trail text of one Coach message",
+      description:
+        "v1.41 — the model-written text of one assistant message's trail: the screened reasoning titles and summaries by trail entry, the fact texts the turn recalled, and a pending fact proposal. The trail's structure (phases, statuses, counts) is plaintext on the message's `metricSource.activity`; this route serves only the text, decrypted for the account that owns the conversation. Fetch lazily when the person opens the trail. A mixed read: while the Coach's text may not be shown for the record, the answer is 200 with `trail: null` and the `ai` state beside it. A foreign or unknown conversation or message id maps to 404 (never 403). Auth via cookie or a full-access Bearer token.",
+      parameters: [
+        {
+          name: "id",
+          in: "path",
+          required: true,
+          schema: { type: "string" },
+          description: "Conversation id.",
+        },
+        {
+          name: "messageId",
+          in: "path",
+          required: true,
+          schema: { type: "string" },
+          description: "Assistant message id within the conversation.",
+        },
+      ],
+      responses: {
+        "200": {
+          description: "The trail text, or null while it may not be served.",
+          content: {
+            "application/json": {
+              schema: dataEnvelope(
+                z.object({
+                  trail: coachTrailSchema.nullable(),
+                  ai: aiCapabilityState.describe(
+                    "The `coach` capability. While unavailable `trail` is null.",
+                  ),
+                }),
+                "CoachMessageTrailResponse",
+              ),
+            },
+          },
+        },
+        "404": {
+          description:
+            "Conversation or message not found, or not owned by the caller.",
+          content: { "application/json": { schema: errorEnvelope } },
+        },
+        ...stdResponses,
+      },
+    },
+  },
   "/api/insights/chat/{id}": {
     get: {
       tags: ["Insights"],