diff --git a/packages/backend/convex/schema.ts b/packages/backend/convex/schema.ts
index 112d570..2fd482d 100644
--- a/packages/backend/convex/schema.ts
+++ b/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).
   // -----------------------------------------------------------------
diff --git a/packages/backend/convex/signals.test.ts b/packages/backend/convex/signals.test.ts
new file mode 100644
index 0000000..5e86781
--- /dev/null
+++ b/packages/backend/convex/signals.test.ts
@@ -0,0 +1,541 @@
+import { type TestConvex, convexTest } from "convex-test";
+import { anyApi } from "convex/server";
+import { describe, expect, test } from "vitest";
+
+import { internal } from "./_generated/api";
+import type { Id } from "./_generated/dataModel";
+import schema from "./schema";
+
+// `import.meta.glob` is provided by the Vitest/Vite test runner at runtime; it
+// has no type definition under the Convex tsconfig (which scopes `types` to
+// node), so declare the minimal shape the test relies on.
+declare global {
+  interface ImportMeta {
+    readonly glob: (pattern: string) => Record<string, () => Promise<unknown>>;
+  }
+}
+
+const modules = import.meta.glob("./**/*.ts");
+const api = anyApi;
+
+const ID_A = "https://convex.test|user-a";
+const ID_B = "https://convex.test|user-b";
+const identityA = { tokenIdentifier: ID_A };
+const identityB = { tokenIdentifier: ID_B };
+
+const newTest = () => convexTest({ schema, modules });
+
+const ensureOrg = async (
+  t: TestConvex<typeof schema>,
+  identity: { readonly tokenIdentifier: string }
+) => {
+  const org = await t
+    .withIdentity(identity)
+    .mutation(api.organizations.ensurePersonalOrganization, {});
+  return org._id as Id<"organizations">;
+};
+
+const problemStatement = {
+  title: "Deploy fails on staging",
+  summary: "The staging deploy command exits with a DNS resolution error.",
+  desiredOutcome: "Staging deploys successfully without DNS errors.",
+  constraints: ["Must not change the production pipeline"],
+};
+
+const processedBy = { agentInstanceId: "zopu-instance-1", agentName: "zopu" };
+
+const repository = {
+  defaultBranch: "main",
+  id: 12345,
+  name: "zopu",
+  owner: "puter",
+  url: "https://github.com/puter/zopu",
+};
+
+// Begin and admit one user message, returning its messageId.
+const seedMessage = async (
+  t: TestConvex<typeof schema>,
+  identity: { readonly tokenIdentifier: string },
+  orgId: Id<"organizations">,
+  clientRequestId: string,
+  rawText: string
+): Promise<string> => {
+  const begun = await t
+    .withIdentity(identity)
+    .mutation(api.conversationMessages.beginUserMessage, {
+      clientRequestId,
+      organizationId: orgId,
+      rawText,
+    });
+  await t
+    .withIdentity(identity)
+    .mutation(api.conversationMessages.markAdmitted, {
+      clientRequestId,
+      organizationId: orgId,
+      submissionId: `sub-${clientRequestId}`,
+    });
+  return begun.messageId;
+};
+
+const createProject = async (
+  t: TestConvex<typeof schema>,
+  ownerId: string,
+  repoId = 12345
+): Promise<Id<"projects">> => {
+  return await t.mutation(internal.projects.storeGitHubProject, {
+    ownerId,
+    repository: { ...repository, id: repoId },
+  });
+};
+
+describe("signals", () => {
+  test("unauthenticated create is rejected", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+
+    await expect(
+      t.mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: ["m1"],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      })
+    ).rejects.toThrow(/Authentication required/u);
+  });
+
+  test("creates one Signal from a single admitted user message", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+    const rawText = "  I cannot deploy to staging  ";
+    const messageId = await seedMessage(t, identityA, orgId, "req-1", rawText);
+
+    const result = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [messageId],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      });
+
+    const composed = await t
+      .withIdentity(identityA)
+      .query(api.signals.get, { signalId: result.signalId });
+
+    expect(composed).not.toBeNull();
+    expect(composed?.signal.organizationId).toBe(orgId);
+    expect(composed?.signal.projectId).toBeNull();
+    expect(composed?.signal.conversationId).toBe(orgId);
+    expect(composed?.sources).toHaveLength(1);
+    expect(composed?.sources[0]?.messageId).toBe(messageId);
+    // Exact raw snapshot preserved verbatim (whitespace intact).
+    expect(composed?.sources[0]?.rawTextSnapshot).toBe(rawText);
+    expect(composed?.sources[0]?.submissionId).toBe("sub-req-1");
+    expect(composed?.sources[0]?.ordinal).toBe(0);
+  });
+
+  test("composes several ordered user messages into one Signal", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+    const m1 = await seedMessage(t, identityA, orgId, "req-a", "first message");
+    const m2 = await seedMessage(
+      t,
+      identityA,
+      orgId,
+      "req-b",
+      "second message"
+    );
+    const m3 = await seedMessage(t, identityA, orgId, "req-c", "third message");
+
+    const result = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [m1, m2, m3],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      });
+
+    const composed = await t
+      .withIdentity(identityA)
+      .query(api.signals.get, { signalId: result.signalId });
+
+    expect(composed?.sources).toHaveLength(3);
+    expect(composed?.sources[0]?.messageId).toBe(m1);
+    expect(composed?.sources[0]?.ordinal).toBe(0);
+    expect(composed?.sources[1]?.messageId).toBe(m2);
+    expect(composed?.sources[1]?.ordinal).toBe(1);
+    expect(composed?.sources[2]?.messageId).toBe(m3);
+    expect(composed?.sources[2]?.ordinal).toBe(2);
+    expect(
+      composed?.sources.map(
+        (s: { rawTextSnapshot: string }) => s.rawTextSnapshot
+      )
+    ).toEqual(["first message", "second message", "third message"]);
+  });
+
+  test("preserves exact raw snapshots and a separate structured problem statement", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+    const rawText = "\n\t  leading and trailing  \n";
+    const messageId = await seedMessage(
+      t,
+      identityA,
+      orgId,
+      "req-exact",
+      rawText
+    );
+
+    const result = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [messageId],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      });
+
+    const composed = await t
+      .withIdentity(identityA)
+      .query(api.signals.get, { signalId: result.signalId });
+
+    // Raw evidence is exact and untouched.
+    expect(composed?.sources[0]?.rawTextSnapshot).toBe(rawText);
+    // The structured problem statement is stored separately.
+    expect(composed?.signal.problemStatement).toEqual(problemStatement);
+  });
+
+  test("rejects cross-organization messages", async () => {
+    const t = newTest();
+    const orgA = await ensureOrg(t, identityA);
+    const orgB = await ensureOrg(t, identityB);
+    // Message belongs to org A.
+    const messageId = await seedMessage(
+      t,
+      identityA,
+      orgA,
+      "req-x",
+      "secret A"
+    );
+
+    // User B tries to build a signal under org B referencing org A's message.
+    await expect(
+      t.withIdentity(identityB).mutation(api.signals.createFromMessages, {
+        conversationId: orgB,
+        messageIds: [messageId],
+        organizationId: orgB,
+        problemStatement,
+        processedBy,
+      })
+    ).rejects.toThrow(/Source message not found/u);
+  });
+
+  test("rejects cross-conversation mismatch", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+    const messageId = await seedMessage(t, identityA, orgId, "req-conv", "hi");
+
+    await expect(
+      t.withIdentity(identityA).mutation(api.signals.createFromMessages, {
+        conversationId: "different-conversation",
+        messageIds: [messageId],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      })
+    ).rejects.toThrow(/Conversation does not belong to organization/u);
+  });
+
+  test("rejects a failed (non-admitted) message", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+
+    // Begin then fail a message.
+    const begun = await t
+      .withIdentity(identityA)
+      .mutation(api.conversationMessages.beginUserMessage, {
+        clientRequestId: "req-failed",
+        organizationId: orgId,
+        rawText: "doomed",
+      });
+    await t
+      .withIdentity(identityA)
+      .mutation(api.conversationMessages.markFailed, {
+        clientRequestId: "req-failed",
+        organizationId: orgId,
+      });
+
+    await expect(
+      t.withIdentity(identityA).mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [begun.messageId],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      })
+    ).rejects.toThrow(/not admitted/u);
+  });
+
+  test("rejects a missing message id", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+
+    await expect(
+      t.withIdentity(identityA).mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: ["nonexistent-id"],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      })
+    ).rejects.toThrow(/Source message not found/u);
+  });
+
+  test("rejects duplicate message ids in the selection", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+    const messageId = await seedMessage(t, identityA, orgId, "req-dup", "dup");
+
+    await expect(
+      t.withIdentity(identityA).mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [messageId, messageId],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      })
+    ).rejects.toThrow(/must be unique/u);
+  });
+
+  test("rejects an empty message selection", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+
+    await expect(
+      t.withIdentity(identityA).mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      })
+    ).rejects.toThrow(/At least one source message is required/u);
+  });
+
+  test("idempotent retry returns the same signal without duplicate sources", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+    const m1 = await seedMessage(t, identityA, orgId, "req-idem-1", "a");
+    const m2 = await seedMessage(t, identityA, orgId, "req-idem-2", "b");
+
+    const first = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [m1, m2],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      });
+
+    // Retry with the same ordered selection.
+    const second = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [m1, m2],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      });
+
+    expect(second.signalId).toBe(first.signalId);
+
+    // Exactly one signal and two sources exist.
+    const list = await t
+      .withIdentity(identityA)
+      .query(api.signals.list, { organizationId: orgId });
+    expect(list).toHaveLength(1);
+    expect(list[0]?.sources).toHaveLength(2);
+  });
+
+  test("different ordered selections produce different signals", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+    const m1 = await seedMessage(t, identityA, orgId, "req-ord-1", "x");
+    const m2 = await seedMessage(t, identityA, orgId, "req-ord-2", "y");
+
+    const first = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [m1, m2],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      });
+    const second = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [m2, m1],
+        organizationId: orgId,
+        problemStatement,
+        processedBy,
+      });
+
+    expect(second.signalId).not.toBe(first.signalId);
+
+    const list = await t
+      .withIdentity(identityA)
+      .query(api.signals.list, { organizationId: orgId });
+    expect(list).toHaveLength(2);
+  });
+
+  test("creates a project-scoped signal when the project owner is an org member", async () => {
+    const t = newTest();
+    const orgId = await ensureOrg(t, identityA);
+    // Project owned by user A, who is a member of orgId.
+    const projectId = await createProject(t, ID_A);
+    const messageId = await seedMessage(
+      t,
+      identityA,
+      orgId,
+      "req-proj",
+      "build"
+    );
+
+    const result = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgId,
+        messageIds: [messageId],
+        organizationId: orgId,
+        problemStatement,
+        projectId,
+        processedBy,
+      });
+
+    const composed = await t
+      .withIdentity(identityA)
+      .query(api.signals.get, { signalId: result.signalId });
+
+    expect(composed?.signal.projectId).toBe(projectId);
+  });
+
+  test("rejects a project whose owner is not an org member (cross-tenant)", async () => {
+    const t = newTest();
+    const orgA = await ensureOrg(t, identityA);
+    const _orgB = await ensureOrg(t, identityB);
+    // Project owned by user B.
+    const projectId = await createProject(t, ID_B);
+    const messageId = await seedMessage(
+      t,
+      identityA,
+      orgA,
+      "req-cross-proj",
+      "z"
+    );
+
+    // User A is a member of orgA but the project owner (B) is not.
+    await expect(
+      t.withIdentity(identityA).mutation(api.signals.createFromMessages, {
+        conversationId: orgA,
+        messageIds: [messageId],
+        organizationId: orgA,
+        problemStatement,
+        projectId,
+        processedBy,
+      })
+    ).rejects.toThrow(/does not belong to the target organization/u);
+  });
+
+  test("authorized list returns only the organization's signals with composed sources", async () => {
+    const t = newTest();
+    const orgA = await ensureOrg(t, identityA);
+    const orgB = await ensureOrg(t, identityB);
+
+    const mA1 = await seedMessage(t, identityA, orgA, "req-list-1", "a1");
+    const mA2 = await seedMessage(t, identityA, orgA, "req-list-2", "a2");
+    await seedMessage(t, identityB, orgB, "req-list-b", "b1");
+
+    await t.withIdentity(identityA).mutation(api.signals.createFromMessages, {
+      conversationId: orgA,
+      messageIds: [mA1],
+      organizationId: orgA,
+      problemStatement,
+      processedBy,
+    });
+    await t.withIdentity(identityA).mutation(api.signals.createFromMessages, {
+      conversationId: orgA,
+      messageIds: [mA1, mA2],
+      organizationId: orgA,
+      problemStatement,
+      processedBy,
+    });
+
+    const forA = await t
+      .withIdentity(identityA)
+      .query(api.signals.list, { organizationId: orgA });
+    const forB = await t
+      .withIdentity(identityB)
+      .query(api.signals.list, { organizationId: orgB });
+
+    expect(forA).toHaveLength(2);
+    expect(forA[0]?.sources.length).toBeGreaterThan(0);
+    expect(forB).toHaveLength(0);
+
+    // Cross-org list is denied.
+    await expect(
+      t
+        .withIdentity(identityB)
+        .query(api.signals.list, { organizationId: orgA })
+    ).rejects.toThrow(/Organization membership required/u);
+  });
+
+  test("authorized get denies cross-organization signal access", async () => {
+    const t = newTest();
+    const orgA = await ensureOrg(t, identityA);
+    const _orgB = await ensureOrg(t, identityB);
+
+    const messageId = await seedMessage(
+      t,
+      identityA,
+      orgA,
+      "req-get",
+      "secret"
+    );
+    const result = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgA,
+        messageIds: [messageId],
+        organizationId: orgA,
+        problemStatement,
+        processedBy,
+      });
+
+    // User B cannot read org A's signal.
+    await expect(
+      t
+        .withIdentity(identityB)
+        .query(api.signals.get, { signalId: result.signalId })
+    ).rejects.toThrow(/Organization membership required/u);
+
+    // get returns null for an unknown but well-formed id when authorized.
+    const other = await t
+      .withIdentity(identityA)
+      .mutation(api.signals.createFromMessages, {
+        conversationId: orgA,
+        messageIds: [await seedMessage(t, identityA, orgA, "req-ghost", "g")],
+        organizationId: orgA,
+        problemStatement,
+        processedBy,
+      });
+    expect(other.signalId).not.toBe(result.signalId);
+  });
+});
diff --git a/packages/backend/convex/signals.ts b/packages/backend/convex/signals.ts
new file mode 100644
index 0000000..2046478
--- /dev/null
+++ b/packages/backend/convex/signals.ts
@@ -0,0 +1,370 @@
+import { composeSignal, SignalValidationError } from "@code/primitives/signal";
+import { ConvexError, v } from "convex/values";
+import { Effect } from "effect";
+
+import type { Doc, Id } from "./_generated/dataModel";
+import {
+  type MutationCtx,
+  mutation,
+  type QueryCtx,
+  query,
+} from "./_generated/server";
+import { requireOrganizationMember } from "./authz";
+
+const PROBLEM_STATEMENT = v.object({
+  title: v.string(),
+  summary: v.string(),
+  desiredOutcome: v.string(),
+  constraints: v.array(v.string()),
+});
+
+interface SignalSourceView {
+  readonly _id: Id<"signalSources">;
+  readonly _creationTime: number;
+  readonly signalId: Id<"signals">;
+  readonly organizationId: Id<"organizations">;
+  readonly conversationId: string;
+  readonly messageId: string;
+  readonly ordinal: number;
+  readonly rawTextSnapshot: string;
+  readonly sourceCreatedAt: number;
+  readonly submissionId: string | null;
+}
+
+interface SignalView {
+  readonly _id: Id<"signals">;
+  readonly _creationTime: number;
+  readonly organizationId: Id<"organizations">;
+  readonly projectId: Id<"projects"> | null;
+  readonly conversationId: string;
+  readonly problemStatement: {
+    readonly title: string;
+    readonly summary: string;
+    readonly desiredOutcome: string;
+    readonly constraints: readonly string[];
+  };
+  readonly processedByAgentName: string;
+  readonly processedByAgentInstanceId: string;
+  readonly createdAt: number;
+}
+
+interface ComposedSignal {
+  readonly signal: SignalView;
+  readonly sources: readonly SignalSourceView[];
+}
+
+const toSignalView = (doc: Doc<"signals">): SignalView => ({
+  _creationTime: doc._creationTime,
+  _id: doc._id,
+  conversationId: doc.conversationId,
+  createdAt: doc.createdAt,
+  organizationId: doc.organizationId,
+  problemStatement: doc.problemStatement,
+  processedByAgentInstanceId: doc.processedByAgentInstanceId,
+  processedByAgentName: doc.processedByAgentName,
+  projectId: doc.projectId ?? null,
+});
+
+const toSourceView = (doc: Doc<"signalSources">): SignalSourceView => ({
+  _creationTime: doc._creationTime,
+  _id: doc._id,
+  conversationId: doc.conversationId,
+  messageId: doc.messageId,
+  ordinal: doc.ordinal,
+  organizationId: doc.organizationId,
+  rawTextSnapshot: doc.rawTextSnapshot,
+  signalId: doc.signalId,
+  sourceCreatedAt: doc.sourceCreatedAt,
+  submissionId: doc.submissionId ?? null,
+});
+
+/**
+ * Build a deterministic, collision-safe key from the organization, the
+ * conversation, and the ordered message selection. The key is the JSON
+ * encoding of `[organizationId, conversationId, ...messageIds]`, so no
+ * delimiter inside arbitrary message IDs can ever cause a collision and the
+ * caller's selection order is part of the identity.
+ */
+const buildSourceKey = (
+  organizationId: Id<"organizations">,
+  conversationId: string,
+  messageIds: readonly string[]
+): string => JSON.stringify([organizationId, conversationId, ...messageIds]);
+
+/**
+ * Resolve all selected conversation messages server-side. Each message must
+ * belong to the same organization and conversation, be a `user` message, be
+ * `admitted`, and appear exactly once in the ordered selection. Raw text,
+ * timestamps, and submission ids are copied from the stored rows; the agent
+ * never supplies them. Returns the messages in the caller's requested order.
+ */
+const resolveSources = async (
+  ctx: MutationCtx,
+  organizationId: Id<"organizations">,
+  conversationId: string,
+  messageIds: readonly string[]
+): Promise<Doc<"conversationMessages">[]> => {
+  if (messageIds.length === 0) {
+    throw new ConvexError("At least one source message is required");
+  }
+  if (new Set(messageIds).size !== messageIds.length) {
+    throw new ConvexError("Source message ids must be unique");
+  }
+  const resolved: Doc<"conversationMessages">[] = [];
+  for (const messageId of messageIds) {
+    const doc = await ctx.db
+      .query("conversationMessages")
+      .withIndex("by_organization_and_message", (q) =>
+        q
+          .eq("organizationId", organizationId)
+          .eq("conversationId", conversationId)
+          .eq("messageId", messageId)
+      )
+      .unique();
+    if (!doc) {
+      throw new ConvexError(`Source message not found: ${messageId}`);
+    }
+    if (doc.role !== "user") {
+      throw new ConvexError(
+        `Source message is not a user message: ${messageId}`
+      );
+    }
+    if (doc.status !== "admitted") {
+      throw new ConvexError(`Source message is not admitted: ${messageId}`);
+    }
+    resolved.push(doc);
+  }
+  return resolved;
+};
+
+/**
+ * Resolve whether an optional project belongs to the same organization. Until
+ * projects carry an explicit `organizationId`, a project is attachable to an
+ * organization's signal only when the project owner is a member of that
+ * organization. The caller is already proven to be a member, so this is a
+ * security-preserving temporary mapping: an organization's project set is the
+ * intersection of (caller is a member) and (project owner is a member), which
+ * cannot weaken cross-tenant isolation.
+ */
+const authorizeProject = async (
+  ctx: MutationCtx,
+  organizationId: Id<"organizations">,
+  projectId: Id<"projects">
+): Promise<void> => {
+  const project = await ctx.db.get(projectId);
+  if (!project) {
+    throw new ConvexError("Project not found");
+  }
+  const ownerMembership = await ctx.db
+    .query("organizationMembers")
+    .withIndex("by_organizationId_and_userId", (q) =>
+      q.eq("organizationId", organizationId).eq("userId", project.ownerId)
+    )
+    .unique();
+  if (!ownerMembership) {
+    throw new ConvexError("Project does not belong to the target organization");
+  }
+};
+
+/**
+ * Atomically create one idempotent Signal from an ordered selection of user
+ * messages plus a structured problem statement produced by the agent.
+ *
+ * Authorization: the authenticated identity must be a member of the target
+ * organization. When a project is supplied it must belong to the same
+ * organization. Every message id is resolved server-side from
+ * `conversationMessages` under the same organization and conversation; raw
+ * text, timestamps, and submission ids are copied from those rows and never
+ * accepted from the agent.
+ *
+ * Idempotency: if a Signal with the same `(organizationId, sourceKey)` already
+ * exists, it is returned as-is without creating duplicate sources. The whole
+ * lookup-or-insert runs in one Convex mutation transaction, so retries cannot
+ * produce duplicates.
+ *
+ * Returns the new (or existing) signal id.
+ */
+export const createFromMessages = mutation({
+  args: {
+    organizationId: v.id("organizations"),
+    projectId: v.optional(v.id("projects")),
+    conversationId: v.string(),
+    messageIds: v.array(v.string()),
+    problemStatement: PROBLEM_STATEMENT,
+    processedBy: v.object({
+      agentName: v.string(),
+      agentInstanceId: v.string(),
+    }),
+  },
+  handler: async (ctx, args): Promise<{ signalId: Id<"signals"> }> => {
+    await requireOrganizationMember(ctx, args.organizationId);
+    if (args.projectId) {
+      await authorizeProject(ctx, args.organizationId, args.projectId);
+    }
+
+    // The global conversation id equals the organization id; the caller's
+    // conversation id must match.
+    if (args.conversationId !== args.organizationId) {
+      throw new ConvexError("Conversation does not belong to organization");
+    }
+
+    const sourceKey = buildSourceKey(
+      args.organizationId,
+      args.conversationId,
+      args.messageIds
+    );
+
+    const existing = await ctx.db
+      .query("signals")
+      .withIndex("by_organization_and_sourceKey", (q) =>
+        q.eq("organizationId", args.organizationId).eq("sourceKey", sourceKey)
+      )
+      .unique();
+    if (existing) {
+      return { signalId: existing._id };
+    }
+
+    const sources = await resolveSources(
+      ctx,
+      args.organizationId,
+      args.conversationId,
+      args.messageIds
+    );
+
+    // Compose the pure Effect Signal before writes, using a prospective id.
+    // `composeSignal` decodes an `unknown` input, so pass plain objects.
+    const now = Date.now();
+    const prospectiveId = crypto.randomUUID();
+    const scope =
+      args.projectId === undefined
+        ? { _tag: "Organization" as const, organizationId: args.organizationId }
+        : {
+            _tag: "Project" as const,
+            organizationId: args.organizationId,
+            projectId: args.projectId,
+          };
+
+    const signal = await Effect.runPromise(
+      composeSignal({
+        createdAt: now,
+        id: prospectiveId,
+        problemStatement: args.problemStatement,
+        processedBy: args.processedBy,
+        scope,
+        sourceMessages: sources.map((doc) => ({
+          conversationId: doc.conversationId,
+          createdAt: doc.createdAt,
+          messageId: doc.messageId,
+          rawText: doc.rawText,
+        })),
+      })
+    ).catch((error: unknown) => {
+      if (error instanceof SignalValidationError) {
+        throw new ConvexError(`Invalid signal: ${error.message}`);
+      }
+      throw new ConvexError(
+        `Invalid signal: ${error instanceof Error ? error.message : "unknown"}`
+      );
+    });
+
+    const signalId = await ctx.db.insert("signals", {
+      conversationId: args.conversationId,
+      createdAt: now,
+      organizationId: args.organizationId,
+      problemStatement: {
+        constraints: [...signal.problemStatement.constraints],
+        desiredOutcome: signal.problemStatement.desiredOutcome,
+        summary: signal.problemStatement.summary,
+        title: signal.problemStatement.title,
+      },
+      processedByAgentInstanceId: args.processedBy.agentInstanceId,
+      processedByAgentName: args.processedBy.agentName,
+      ...(args.projectId === undefined ? {} : { projectId: args.projectId }),
+      sourceKey,
+    });
+
+    await Promise.all(
+      sources.map((doc, ordinal) =>
+        ctx.db.insert("signalSources", {
+          conversationId: doc.conversationId,
+          messageId: doc.messageId,
+          ordinal,
+          organizationId: args.organizationId,
+          rawTextSnapshot: doc.rawText,
+          signalId,
+          ...(doc.submissionId === undefined
+            ? {}
+            : { submissionId: doc.submissionId }),
+          sourceCreatedAt: doc.createdAt,
+        })
+      )
+    );
+
+    return { signalId };
+  },
+});
+
+/**
+ * Load the composed source rows for a signal in ordinal order.
+ */
+const loadComposedSources = async (
+  ctx: QueryCtx,
+  signal: Doc<"signals">
+): Promise<SignalSourceView[]> => {
+  const rows = await ctx.db
+    .query("signalSources")
+    .withIndex("by_signal_and_ordinal", (q) => q.eq("signalId", signal._id))
+    .collect();
+  // `collect` does not guarantee index order across all backends; sort by
+  // ordinal to be deterministic.
+  rows.sort((a, b) => a.ordinal - b.ordinal);
+  return rows.map(toSourceView);
+};
+
+/**
+ * List the Signals for the authenticated user's organization, newest first.
+ * Membership is required; cross-organization access is denied. Each entry
+ * includes its composed source records in ordinal order.
+ */
+export const list = query({
+  args: {
+    organizationId: v.id("organizations"),
+  },
+  handler: async (ctx, args): Promise<ComposedSignal[]> => {
+    await requireOrganizationMember(ctx, args.organizationId);
+    const signals = await ctx.db
+      .query("signals")
+      .withIndex("by_organization_and_createdAt", (q) =>
+        q.eq("organizationId", args.organizationId)
+      )
+      .order("desc")
+      .take(50);
+    return Promise.all(
+      signals.map(async (signal) => ({
+        signal: toSignalView(signal),
+        sources: await loadComposedSources(ctx, signal),
+      }))
+    );
+  },
+});
+
+/**
+ * Get one Signal by id with its composed sources. Membership in the signal's
+ * organization is required; access to another organization's signal is denied.
+ */
+export const get = query({
+  args: {
+    signalId: v.id("signals"),
+  },
+  handler: async (ctx, args): Promise<ComposedSignal | null> => {
+    const signal = await ctx.db.get(args.signalId);
+    if (!signal) {
+      return null;
+    }
+    await requireOrganizationMember(ctx, signal.organizationId);
+    return {
+      signal: toSignalView(signal),
+      sources: await loadComposedSources(ctx, signal),
+    };
+  },
+});