feat(cli): dispatch du callback plugin slash-command vers le runtime registry — #166 (QA verte)

Boucle le gap end-to-end de #165 : à l'exécution d'une commande slash plugin
depuis le composer custom, l'UI traite l'effet pluginCallback et le dispatche
au PluginRuntimeRegistry pour que la callback du plugin s'exécute réellement.

- runtime/registry: runCommandStrict (échec explicite si handler absent) +
  propagation de la valeur de retour ; élargit les types de retour (unknown).
- runtime/loader: chargement de contributes.slashCommands au registre +
  propagation du retour du handler.
- features/plugins/usePluginMenus: runCommand retourne unknown.
- features/agents/CustomAgentChatView: handler de l'effet pluginCallback ->
  pluginRuntime.registry.runCommandStrict, avec retour utilisateur en cas
  d'échec (commande indisponible / callback absente).

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

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

@@ -4,6 +4,13 @@ import { describe, expect, it, vi } from "vitest";
 
 import { DIProvider } from "@/app/di";
 import type { AgentProfile } from "@/domain";
+import { PluginRuntimeProvider } from "@/features/plugins";
+import {
+  PluginCommandRegistry,
+  PluginLayoutRegistry,
+  PluginMenuRegistry,
+  PluginRuntimeRegistry,
+} from "@/plugins/runtime";
 import type { Gateways } from "@/ports";
 import { CustomAgentChatView } from "./CustomAgentChatView";
 
@@ -18,6 +25,27 @@ const profile: AgentProfile = {
   structuredAdapter: "codex",
 };
 
+function addPluginCommand(
+  registry: PluginRuntimeRegistry,
+  pluginId: string,
+  commandId: string,
+  handler: (...args: unknown[]) => unknown | Promise<unknown>,
+) {
+  const commands = new PluginCommandRegistry(pluginId, new Set([commandId]));
+  commands.register(commandId, handler);
+  registry.add({
+    pluginId,
+    displayName: "Acme Plugin",
+    contributes: {
+      commands: [{ id: commandId, title: "Explain", shortDescription: "Explain selection" }],
+    },
+    commands,
+    layouts: new PluginLayoutRegistry(pluginId, new Set()),
+    menu: new PluginMenuRegistry(pluginId),
+    dispose: async () => {},
+  });
+}
+
 describe("CustomAgentChatView", () => {
   it("cancels only the current turn and keeps the structured session alive", async () => {
     const agent = {
@@ -522,6 +550,173 @@ describe("CustomAgentChatView", () => {
     expect(screen.queryByRole("listbox", { name: "suggestions commandes slash" })).toBeNull();
   });
 
+  it("dispatches plugin slash-command callback effects through the plugin runtime", async () => {
+    const commandHandler = vi.fn(async () => {});
+    const registry = new PluginRuntimeRegistry();
+    addPluginCommand(
+      registry,
+      "dev.acme.explain",
+      "dev.acme.explain.run",
+      commandHandler,
+    );
+    const agent = {
+      launchAgentChat: vi.fn(),
+      reattachAgentChat: vi.fn(async (sessionId: string) => ({
+        sessionId,
+        scrollback: [],
+      })),
+      sendAgentChat: vi.fn(async () => {}),
+      executeSlashCommand: vi.fn(async (_name: string, options) => ({
+        command: {
+          name: "/explain",
+          shortDescription: "Explain selection",
+          requiresConfirmation: false,
+          availability: { status: "available" as const },
+          source: { plugin: { pluginId: "dev.acme.explain" } },
+          plugin: {
+            pluginId: "dev.acme.explain",
+            commandId: "dev.acme.explain.run",
+          },
+        },
+        effect: {
+          kind: "pluginCallback" as const,
+          pluginId: "dev.acme.explain",
+          commandId: "dev.acme.explain.run",
+          sessionId: options.sessionId,
+          arguments: options.arguments ?? [],
+        },
+      })),
+      cancelAgentChat: vi.fn(async () => {}),
+      closeAgentChat: vi.fn(async () => {}),
+    };
+
+    render(
+      <DIProvider
+        gateways={{
+          agent,
+          system: { pickFile: vi.fn(async () => null) },
+        } as unknown as Gateways}
+      >
+        <PluginRuntimeProvider
+          value={{ registry, failures: [], pending: [], loading: false }}
+        >
+          <CustomAgentChatView
+            projectId="project-1"
+            agentId="agent-1"
+            agentName="Worker"
+            profile={profile}
+            cwd="/repo"
+            nodeId="node-1"
+            sessionId="chat-session-1"
+            conversationId="conversation-1"
+            onSessionId={vi.fn()}
+            onConversationId={vi.fn()}
+          />
+        </PluginRuntimeProvider>
+      </DIProvider>,
+    );
+
+    await waitFor(() =>
+      expect(agent.reattachAgentChat).toHaveBeenCalledWith(
+        "chat-session-1",
+        expect.any(Function),
+      ),
+    );
+
+    const composer = screen.getByLabelText(/message CLI custom/) as HTMLTextAreaElement;
+    fireEvent.change(composer, { target: { value: "/explain focus this" } });
+    fireEvent.keyDown(composer, { key: "Enter" });
+
+    await waitFor(() =>
+      expect(agent.executeSlashCommand).toHaveBeenCalledWith("/explain", {
+        sessionId: "chat-session-1",
+        arguments: ["focus this"],
+      }),
+    );
+    await waitFor(() => expect(commandHandler).toHaveBeenCalledWith("focus this"));
+    expect(agent.sendAgentChat).not.toHaveBeenCalled();
+    expect(
+      await screen.findByText("Commande plugin /explain exécutée."),
+    ).toBeTruthy();
+    expect(composer.value).toBe("");
+  });
+
+  it("shows feedback when a plugin slash-command callback cannot be dispatched", async () => {
+    const registry = new PluginRuntimeRegistry();
+    const agent = {
+      launchAgentChat: vi.fn(),
+      reattachAgentChat: vi.fn(async (sessionId: string) => ({
+        sessionId,
+        scrollback: [],
+      })),
+      sendAgentChat: vi.fn(async () => {}),
+      executeSlashCommand: vi.fn(async () => ({
+        command: {
+          name: "/explain",
+          shortDescription: "Explain selection",
+          requiresConfirmation: false,
+          availability: { status: "available" as const },
+          source: { plugin: { pluginId: "dev.acme.missing" } },
+          plugin: {
+            pluginId: "dev.acme.missing",
+            commandId: "dev.acme.missing.run",
+          },
+        },
+        effect: {
+          kind: "pluginCallback" as const,
+          pluginId: "dev.acme.missing",
+          commandId: "dev.acme.missing.run",
+          arguments: [],
+        },
+      })),
+      cancelAgentChat: vi.fn(async () => {}),
+      closeAgentChat: vi.fn(async () => {}),
+    };
+
+    render(
+      <DIProvider
+        gateways={{
+          agent,
+          system: { pickFile: vi.fn(async () => null) },
+        } as unknown as Gateways}
+      >
+        <PluginRuntimeProvider
+          value={{ registry, failures: [], pending: [], loading: false }}
+        >
+          <CustomAgentChatView
+            projectId="project-1"
+            agentId="agent-1"
+            agentName="Worker"
+            profile={profile}
+            cwd="/repo"
+            nodeId="node-1"
+            sessionId="chat-session-1"
+            conversationId="conversation-1"
+            onSessionId={vi.fn()}
+            onConversationId={vi.fn()}
+          />
+        </PluginRuntimeProvider>
+      </DIProvider>,
+    );
+
+    await waitFor(() =>
+      expect(agent.reattachAgentChat).toHaveBeenCalledWith(
+        "chat-session-1",
+        expect.any(Function),
+      ),
+    );
+
+    const composer = screen.getByLabelText(/message CLI custom/);
+    fireEvent.change(composer, { target: { value: "/explain" } });
+    fireEvent.keyDown(composer, { key: "Enter" });
+
+    const alert = await screen.findByRole("alert");
+    expect(alert.textContent).toContain("Commande /explain échouée");
+    expect(alert.textContent).toContain('plugin "dev.acme.missing" is not loaded');
+    expect(screen.getAllByText(/Commande \/explain échouée/)).toHaveLength(2);
+    expect(agent.sendAgentChat).not.toHaveBeenCalled();
+  });
+
   it("executes /profile as a confirmed profile-switch flow that resets the current session", async () => {
     const agent = {
       launchAgentChat: vi.fn(async () => ({

frontend/src/features/agents/CustomAgentChatView.tsx

@@ -26,6 +26,7 @@ import type {
   SlashCommand,
 } from "@/domain";
 import { useGateways } from "@/app/di";
+import { usePluginRuntime } from "@/features/plugins/PluginRuntimeProvider";
 import { Button, Spinner, cn } from "@/shared";
 import type { ChatAttachmentInput } from "@/ports";
 
@@ -66,6 +67,11 @@ interface ProfileCommandDialogState {
   error: string | null;
 }
 
+interface SlashCommandInvocation {
+  name: string;
+  arguments: unknown[];
+}
+
 function describe(e: unknown): string {
   if (e && typeof e === "object" && "message" in e) {
     return String((e as GatewayError).message);
@@ -274,6 +280,17 @@ function slashCommandPrefix(draft: string): string | null {
   return draft;
 }
 
+function slashCommandInvocation(text: string): SlashCommandInvocation | null {
+  if (!text.startsWith("/")) return null;
+  const [name, ...argumentParts] = text.split(/\s+/);
+  if (!name) return null;
+  const rawArguments = argumentParts.join(" ").trim();
+  return {
+    name,
+    arguments: rawArguments ? [rawArguments] : [],
+  };
+}
+
 function isSlashCommandAvailable(command: SlashCommand): boolean {
   return command.availability.status === "available";
 }
@@ -328,6 +345,7 @@ export function CustomAgentChatView({
   onConversationId,
 }: CustomAgentChatViewProps) {
   const { agent, profile: profileGateway, system } = useGateways();
+  const pluginRuntime = usePluginRuntime();
   const [turns, setTurns] = useState<ChatTurn[]>([]);
   const [currentSession, setCurrentSession] = useState(sessionId);
   const [externalSessionId, setExternalSessionId] = useState(sessionId);
@@ -756,6 +774,45 @@ export function CustomAgentChatView({
     }
   }
 
+  async function executeSlashCommand(invocation: SlashCommandInvocation) {
+    if (!agent.executeSlashCommand) {
+      setError(`Commande ${invocation.name} indisponible dans ce runtime.`);
+      return;
+    }
+    setDraft("");
+    setError(null);
+    try {
+      const sid =
+        currentSession ??
+        (await recoverStructuredSession({
+          applyScrollback: false,
+          retryAttachNotFound: true,
+        }));
+      const result = await agent.executeSlashCommand(invocation.name, {
+        sessionId: sid,
+        arguments: invocation.arguments,
+      });
+      if (result.effect.kind !== "pluginCallback") {
+        throw new Error(
+          `La commande ${invocation.name} n'a pas renvoyé d'effet pluginCallback.`,
+        );
+      }
+      await pluginRuntime.registry.runCommandStrict(
+        result.effect.pluginId,
+        result.effect.commandId,
+        ...result.effect.arguments,
+      );
+      setTurns((prev) => [
+        ...prev,
+        { role: "tool", label: `Commande plugin ${result.command.name} exécutée.` },
+      ]);
+    } catch (e) {
+      const message = `Commande ${invocation.name} échouée: ${describe(e)}`;
+      setError(message);
+      setTurns((prev) => [...prev, { role: "error", text: message }]);
+    }
+  }
+
   async function pickAttachment() {
     const path = await system.pickFile();
     if (path) {
@@ -804,6 +861,11 @@ export function CustomAgentChatView({
       await openProfileCommandFlow();
       return;
     }
+    const slashInvocation = slashCommandInvocation(text);
+    if (slashInvocation) {
+      await executeSlashCommand(slashInvocation);
+      return;
+    }
     const outgoingAttachments = attachments;
     const attachmentInputs = outgoingAttachments.map((item) => item.input);
     const attachmentLabels = outgoingAttachments.map((item) => item.label);

frontend/src/features/plugins/usePluginMenus.ts

@@ -23,7 +23,7 @@ export interface UsePluginMenusResult {
   topLevelMenus: MenuBarMenu[];
   /** Resolved+ordered `MenuBarItem`s to append to a native menu's items. */
   itemsFor: (targetMenuId: MenuTargetId) => MenuBarItem[];
-  runCommand: (pluginId: string, commandId: string) => Promise<void>;
+  runCommand: (pluginId: string, commandId: string) => Promise<unknown>;
 }
 
 function describeError(e: unknown): string {