feat(frontend): système de plugins — runtime, menus, layouts custom (#43)

Lots F1-F4 : runtime de chargement/registre plugin, extension des menus
existants, panneau de gestion des plugins, types de layout custom
(sélecteur, fallback, cellule dédiée) branchés sur le port plugin.
Suite npm typecheck/test verte (947/947).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/features/plugins/menus.test.ts

@@ -0,0 +1,155 @@
+/**
+ * F3 — plugin menu contribution resolution (ticket #43, carnet §10 F3
+ * acceptance criteria: "ordre déterministe, disabledReason, plugin disabled
+ * absent, command handler appelé").
+ */
+import { describe, expect, it } from "vitest";
+
+import type { PluginContributionDto } from "@/domain";
+import { PluginRuntimeRegistry, type LoadedPlugin, type WhenContext } from "@/plugins/runtime";
+import { PluginCommandRegistry, PluginLayoutRegistry, PluginMenuRegistry } from "@/plugins/runtime";
+import { resolveMenuItems, resolveTopLevelMenus } from "./menus";
+
+const NO_CONTEXT: WhenContext = {
+  projectOpen: false,
+  gitRepository: false,
+  agentSelected: false,
+  terminalFocused: false,
+  layoutCellFocused: false,
+};
+
+function stubPlugin(pluginId: string, displayName: string, contributes: PluginContributionDto): LoadedPlugin {
+  return {
+    pluginId,
+    displayName,
+    contributes,
+    commands: new PluginCommandRegistry(pluginId, new Set(contributes.menuItems.map((i) => i.command))),
+    layouts: new PluginLayoutRegistry(pluginId, new Set(contributes.layouts.map((l) => l.type))),
+    menu: new PluginMenuRegistry(pluginId),
+    dispose: async () => {},
+  };
+}
+
+function empty(): PluginContributionDto {
+  return { menus: [], menuItems: [], layouts: [], mcpServers: [] };
+}
+
+describe("resolveTopLevelMenus", () => {
+  it("sorts by order, then plugin display name, then label", () => {
+    const registry = new PluginRuntimeRegistry();
+    registry.add(
+      stubPlugin("dev.b", "Beta", {
+        ...empty(),
+        menus: [{ id: "b.menu", label: "B Menu", topLevel: true, order: 0 }],
+      }),
+    );
+    registry.add(
+      stubPlugin("dev.a", "Alpha", {
+        ...empty(),
+        menus: [{ id: "a.menu", label: "A Menu", topLevel: true, order: 0 }],
+      }),
+    );
+    registry.add(
+      stubPlugin("dev.z", "Zulu", {
+        ...empty(),
+        menus: [{ id: "z.menu", label: "Z Menu", topLevel: true, order: -1 }],
+      }),
+    );
+
+    const resolved = resolveTopLevelMenus(registry);
+    expect(resolved.map((m) => m.label)).toEqual(["Z Menu", "A Menu", "B Menu"]);
+  });
+});
+
+describe("resolveMenuItems", () => {
+  it("only returns items targeting the requested menu, and only from loaded (i.e. enabled) plugins", () => {
+    const registry = new PluginRuntimeRegistry();
+    registry.add(
+      stubPlugin("dev.acme", "Acme", {
+        ...empty(),
+        menuItems: [
+          { id: "dev.acme.a", targetMenuId: "panels", label: "Open A", command: "dev.acme.a.cmd" },
+          { id: "dev.acme.b", targetMenuId: "settings", label: "Open B", command: "dev.acme.b.cmd" },
+        ],
+      }),
+    );
+    // A disabled plugin never appears in the registry at all (carnet §1.3) —
+    // simulated here by simply not adding it.
+
+    const panelsItems = resolveMenuItems(registry, "panels", NO_CONTEXT);
+    expect(panelsItems).toHaveLength(1);
+    expect(panelsItems[0].label).toBe("Open A");
+
+    const settingsItems = resolveMenuItems(registry, "settings", NO_CONTEXT);
+    expect(settingsItems).toHaveLength(1);
+    expect(settingsItems[0].label).toBe("Open B");
+  });
+
+  it("evaluates `when` and disables with a diagnostic reason on failure, enables on success", () => {
+    const registry = new PluginRuntimeRegistry();
+    registry.add(
+      stubPlugin("dev.acme", "Acme", {
+        ...empty(),
+        menuItems: [
+          {
+            id: "dev.acme.needs-git",
+            targetMenuId: "panels",
+            label: "Needs git",
+            command: "dev.acme.git.cmd",
+            when: "gitRepository",
+          },
+          {
+            id: "dev.acme.broken-when",
+            targetMenuId: "panels",
+            label: "Broken when",
+            command: "dev.acme.broken.cmd",
+            when: "notAVariable",
+          },
+        ],
+      }),
+    );
+
+    const withoutGit = resolveMenuItems(registry, "panels", NO_CONTEXT);
+    const needsGit = withoutGit.find((i) => i.label === "Needs git")!;
+    expect(needsGit.enabled).toBe(false);
+    expect(needsGit.disabledReason).toBeUndefined();
+
+    const withGit = resolveMenuItems(registry, "panels", { ...NO_CONTEXT, gitRepository: true });
+    expect(withGit.find((i) => i.label === "Needs git")!.enabled).toBe(true);
+
+    const broken = withoutGit.find((i) => i.label === "Broken when")!;
+    expect(broken.enabled).toBe(false);
+    expect(broken.disabledReason).toMatch(/unknown variable/);
+  });
+
+  it("sorts resolved items deterministically", () => {
+    const registry = new PluginRuntimeRegistry();
+    registry.add(
+      stubPlugin("dev.acme", "Acme", {
+        ...empty(),
+        menuItems: [
+          { id: "dev.acme.z", targetMenuId: "panels", label: "Z item", command: "dev.acme.z.cmd", order: 1 },
+          { id: "dev.acme.a", targetMenuId: "panels", label: "A item", command: "dev.acme.a.cmd", order: 0 },
+        ],
+      }),
+    );
+    const items = resolveMenuItems(registry, "panels", NO_CONTEXT);
+    expect(items.map((i) => i.label)).toEqual(["A item", "Z item"]);
+  });
+
+  it("dispatches a command via the registry's runCommand", async () => {
+    const registry = new PluginRuntimeRegistry();
+    let ran = false;
+    const plugin = stubPlugin("dev.acme", "Acme", {
+      ...empty(),
+      menuItems: [{ id: "dev.acme.a", targetMenuId: "panels", label: "Open A", command: "dev.acme.a.cmd" }],
+    });
+    plugin.commands.register("dev.acme.a.cmd", () => {
+      ran = true;
+    });
+    registry.add(plugin);
+
+    await registry.runCommand("dev.acme", "dev.acme.a.cmd");
+    expect(ran).toBe(true);
+  });
+});