feat(agents): role orchestrateur du contexte global expose et configurable par agent — isOrchestrator distinct des permissions MCP, DTO update_project_orchestrator (terminologie wire legacy conservee), refus idea_context_update explicite avec writer effectif + orientation idea_context_propose, surface AgentsPanel + adaptateurs frontend — #276 (QA verte: cargo fmt/check, tests cibles application/app-tauri/infrastructure/backend, npm typecheck, 69/69 tests frontend agents/adapters)

frontend/src/adapters/agent.test.ts

@@ -176,6 +176,18 @@ describe("TauriAgentGateway invoke payloads", () => {
     });
   });
 
+  it("update_project_orchestrator wraps the project and agent in the request DTO", async () => {
+    invoke.mockResolvedValueOnce({ orchestratorAgentId: "agent-2" });
+
+    await expect(
+      new TauriAgentGateway().updateProjectOrchestrator("proj-1", "agent-2"),
+    ).resolves.toEqual({ orchestratorAgentId: "agent-2" });
+
+    expect(invoke).toHaveBeenCalledWith("update_project_orchestrator", {
+      request: { projectId: "proj-1", agentId: "agent-2" },
+    });
+  });
+
   it("cancelAgentChat invokes cancel_agent_chat without closing the session", async () => {
     await new TauriAgentGateway().cancelAgentChat("chat-session-1");
 

frontend/src/adapters/agent.ts

@@ -154,6 +154,16 @@ export class TauriAgentGateway implements AgentGateway {
     });
   }
 
+  updateProjectOrchestrator(
+    projectId: string,
+    agentId: string,
+  ): Promise<{ orchestratorAgentId: string }> {
+    return invoke<{ orchestratorAgentId: string }>(
+      "update_project_orchestrator",
+      { request: { projectId, agentId } },
+    );
+  }
+
   readContext(projectId: string, agentId: string): Promise<string> {
     return invoke<AgentContextDocument>("read_agent_context", {
       projectId,

frontend/src/adapters/http/agentGateway.test.ts

@@ -141,6 +141,26 @@ describe("HttpAgentGateway WS round-trip (B6 frames)", () => {
     });
   });
 
+  it("updates the project orchestrator through the dedicated request DTO", async () => {
+    const response = { orchestratorAgentId: "agent-2" };
+    const { gw, calls } = httpAgentGateway(async () => ({
+      ok: true,
+      status: 200,
+      json: async () => response,
+      text: async () => JSON.stringify(response),
+    }));
+
+    await expect(
+      gw.updateProjectOrchestrator("proj-1", "agent-2"),
+    ).resolves.toEqual(response);
+
+    const init = calls[0].init as { body: string };
+    expect(JSON.parse(init.body)).toEqual({
+      command: "update_project_orchestrator",
+      args: { request: { projectId: "proj-1", agentId: "agent-2" } },
+    });
+  });
+
   it("launch → attached: conforming agent.launch frame, assignedConversationId consumed", async () => {
     const { gw, sockets } = gateway();
     const chunks: Uint8Array[] = [];

frontend/src/adapters/http/streamGateways.ts

@@ -258,6 +258,15 @@ export class HttpAgentGateway implements AgentGateway {
       request: { projectId, agentId, contactable },
     });
   }
+  updateProjectOrchestrator(
+    projectId: string,
+    agentId: string,
+  ): Promise<{ orchestratorAgentId: string }> {
+    return this.http.invoke<{ orchestratorAgentId: string }>(
+      "update_project_orchestrator",
+      { request: { projectId, agentId } },
+    );
+  }
   readContext(projectId: string, agentId: string): Promise<string> {
     return this.http
       .invoke<AgentContextDocument>("read_agent_context", { projectId, agentId })

frontend/src/adapters/mock/index.ts

@@ -720,6 +720,24 @@ export class MockAgentGateway implements AgentGateway {
     return structuredClone(list[idx]);
   }
 
+  async updateProjectOrchestrator(
+    projectId: string,
+    agentId: string,
+  ): Promise<{ orchestratorAgentId: string }> {
+    const list = this.getAgents(projectId);
+    if (!list.some((agent) => agent.id === agentId)) {
+      const err: GatewayError = {
+        code: "NOT_FOUND",
+        message: `agent ${agentId} not found in project ${projectId}`,
+      };
+      throw err;
+    }
+    for (let index = 0; index < list.length; index += 1) {
+      list[index] = { ...list[index], isOrchestrator: list[index].id === agentId };
+    }
+    return { orchestratorAgentId: agentId };
+  }
+
   // ── Internal helpers for MockTemplateGateway (same-package use only) ──
 
   /**