feat(agent): orchestration v3 — surface MCP model-agnostic (M0→M4) — §14.3

Expose l'orchestration IdeA comme serveur MCP par-dessus le même
OrchestratorService::dispatch, avec repli fichier .ideai/requests pour les
CLI sans MCP. v3 réduite à la surface MCP : la messagerie inter-agents et la
corrélation requête↔réponse étaient déjà résolues par §17 (send_blocking).

- M0 capacité MCP sur le profil (McpCapability/McpConfigStrategy/McpTransport)
- M1 injection conf MCP au LaunchAgent + prose adaptée selon la surface
- M2 serveur/adapter MCP (JSON-RPC 2.0 maison ; outils idea_*) + ListAgents
- M3 câblage par projet (registre mcp_servers jumeau du watcher)
- M4 observabilité UI : OrchestratorRequestProcessed.source = file|mcp + badge

Trois portes d'entrée (fichier, MCP, UI) → un seul dispatch ; aucun nouveau
port applicatif ; MCP confiné à l'adapter infra. Tous lots verts (cycle §3).
Cadrage : .ideai/briefs/orchestration-v3-cadrage.md ; ARCHITECTURE.md §14.3.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/features/agents/agents.test.tsx

@@ -582,3 +582,94 @@ describe("AgentsPanel live refresh on domain events", () => {
     expect(screen.getByText("No agents yet.")).toBeTruthy();
   });
 });
+
+// ---------------------------------------------------------------------------
+// M4 — orchestration source badge (mcp / file) on `orchestratorRequestProcessed`
+// ---------------------------------------------------------------------------
+
+describe("AgentsPanel orchestration source badge (M4)", () => {
+  /** Mounts the panel with a live `MockSystemGateway`, returning all the pieces. */
+  async function renderWithSystem() {
+    const agent = new MockAgentGateway();
+    const profile = new MockProfileGateway();
+    const system = new MockSystemGateway();
+    const template = new MockTemplateGateway(agent);
+    const gateways = { agent, profile, system, template } as unknown as Gateways;
+    // The badge keys on `a.id === requesterId`, so create the agent first and use
+    // its id as the requester in the emitted event.
+    const created = await agent.createAgent(PROJECT_ID, {
+      name: "Requester",
+      profileId: "p1",
+    });
+    render(
+      <DIProvider gateways={gateways}>
+        <AgentsPanel projectId={PROJECT_ID} projectRoot="/home/me/proj" />
+      </DIProvider>,
+    );
+    await waitFor(() => expect(screen.getByText("Requester")).toBeTruthy());
+    return { agent, system, created };
+  }
+
+  it("shows an `mcp` badge when a delegation arrives via the MCP door", async () => {
+    const { system, created } = await renderWithSystem();
+
+    system.emit({
+      type: "orchestratorRequestProcessed",
+      requesterId: created.id,
+      action: "idea_ask_agent",
+      ok: true,
+      source: "mcp",
+    });
+
+    const badge = await screen.findByLabelText("delegation source mcp");
+    expect(badge.textContent?.toLowerCase()).toContain("mcp");
+  });
+
+  it("shows a `file` badge when a delegation arrives via the .ideai/requests door", async () => {
+    const { system, created } = await renderWithSystem();
+
+    system.emit({
+      type: "orchestratorRequestProcessed",
+      requesterId: created.id,
+      action: "spawn_agent",
+      ok: true,
+      source: "file",
+    });
+
+    const badge = await screen.findByLabelText("delegation source file");
+    expect(badge.textContent?.toLowerCase()).toContain("file");
+  });
+
+  it("renders NO badge when the event carries no `source` (older backend)", async () => {
+    const { system, created } = await renderWithSystem();
+
+    // Same requester, but the event omits `source` entirely.
+    system.emit({
+      type: "orchestratorRequestProcessed",
+      requesterId: created.id,
+      action: "spawn_agent",
+      ok: true,
+    });
+
+    // Give the effect a tick; the map must stay empty → no badge for any source.
+    await waitFor(() => expect(screen.getByText("Requester")).toBeTruthy());
+    expect(screen.queryByLabelText("delegation source mcp")).toBeNull();
+    expect(screen.queryByLabelText("delegation source file")).toBeNull();
+  });
+
+  it("does not badge an agent whose id never matched a processed requester", async () => {
+    const { system } = await renderWithSystem();
+
+    // A processed event for a *different* requester id leaves our agent un-badged.
+    system.emit({
+      type: "orchestratorRequestProcessed",
+      requesterId: "some-other-requester",
+      action: "idea_ask_agent",
+      ok: true,
+      source: "mcp",
+    });
+
+    await waitFor(() => expect(screen.getByText("Requester")).toBeTruthy());
+    expect(screen.queryByLabelText("delegation source mcp")).toBeNull();
+  });
+});