feat(schema): add signals and signal sources tables

packages/backend/convex/schema.ts

@@ -199,6 +199,52 @@ export default defineSchema({
       "clientRequestId",
     ]),
 
+  // -----------------------------------------------------------------
+  // Product Signals. A Signal is the agent-produced interpretation of one
+  // or more exact user messages into a structured problem statement. It is
+  // organization-scoped, optionally project-scoped, and idempotent by
+  // organization + ordered source-message selection (`sourceKey`). Raw text
+  // is never accepted from the agent: it is copied server-side from the
+  // normalized conversation messages into immutable source snapshots.
+  // -----------------------------------------------------------------
+  signals: defineTable({
+    organizationId: v.id("organizations"),
+    projectId: v.optional(v.id("projects")),
+    conversationId: v.string(),
+    sourceKey: v.string(),
+    problemStatement: v.object({
+      title: v.string(),
+      summary: v.string(),
+      desiredOutcome: v.string(),
+      constraints: v.array(v.string()),
+    }),
+    processedByAgentName: v.string(),
+    processedByAgentInstanceId: v.string(),
+    createdAt: v.number(),
+  })
+    .index("by_organization_and_createdAt", ["organizationId", "createdAt"])
+    .index("by_organization_and_sourceKey", ["organizationId", "sourceKey"])
+    .index("by_project_and_createdAt", ["projectId", "createdAt"]),
+
+  // Immutable ordered source snapshots copied from `conversationMessages`.
+  // `ordinal` is the zero-based position in the agent's ordered selection.
+  signalSources: defineTable({
+    signalId: v.id("signals"),
+    organizationId: v.id("organizations"),
+    conversationId: v.string(),
+    messageId: v.string(),
+    ordinal: v.number(),
+    rawTextSnapshot: v.string(),
+    sourceCreatedAt: v.number(),
+    submissionId: v.optional(v.string()),
+  })
+    .index("by_signal_and_ordinal", ["signalId", "ordinal"])
+    .index("by_organization_and_message", [
+      "organizationId",
+      "conversationId",
+      "messageId",
+    ]),
+
   // -----------------------------------------------------------------
   // Flue persistence stores (schema/format version 4).
   // -----------------------------------------------------------------