Merge feature/ticket50-open-windows-menu-state into develop

Ticket #50 : commande backend `list_open_view_windows` + consommateur
frontend qui réconcilie l'état du menu Panneaux avec les fenêtres
détachées réellement ouvertes. Validé QA vert (frontend
typecheck+build+677 tests ; backend cargo check/build + 7 tests
view_window).

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

crates/app-tauri/src/commands.rs

@@ -2336,6 +2336,18 @@ pub struct CloseViewWindowResponseDto {
     pub closed: bool,
 }
 
+/// Snapshot returned by `list_open_view_windows`.
+#[derive(Debug, Clone, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ViewWindowSnapshot {
+    /// Panel id rendered by the detached window.
+    pub panel: String,
+    /// Stable Tauri window label.
+    pub label: String,
+    /// Whether Tauri currently reports the OS window as visible.
+    pub visible: bool,
+}
+
 /// Payload emitted on `view-window://lifecycle`.
 #[derive(Debug, Clone, Serialize)]
 #[serde(rename_all = "camelCase")]
@@ -2429,6 +2441,19 @@ pub(crate) fn view_window_url(panel: ViewPanel) -> String {
     format!("index.html?panel={}", panel.as_str())
 }
 
+fn view_panel_from_window_label(label: &str) -> Option<ViewPanel> {
+    let rest = label.strip_prefix("view-")?;
+    if let Ok(panel) = ViewPanel::parse(rest) {
+        return Some(panel);
+    }
+
+    let (panel, project_id) = rest.rsplit_once('-')?;
+    if project_id.len() != 32 || uuid::Uuid::parse_str(project_id).is_err() {
+        return None;
+    }
+    ViewPanel::parse(panel).ok()
+}
+
 pub(crate) fn emit_view_window_lifecycle(
     app: &AppHandle,
     kind: &'static str,
@@ -2468,6 +2493,30 @@ pub async fn get_focused_project(
     Ok(state.get_focused_project())
 }
 
+/// `list_open_view_windows` — return the detached panel windows currently
+/// registered by Tauri.
+#[tauri::command]
+pub fn list_open_view_windows(app: AppHandle) -> Vec<ViewWindowSnapshot> {
+    let mut windows = app
+        .webview_windows()
+        .into_iter()
+        .filter_map(|(label, window)| {
+            let panel = view_panel_from_window_label(&label)?;
+            Some(ViewWindowSnapshot {
+                panel: panel.as_str().to_owned(),
+                label,
+                visible: window.is_visible().unwrap_or(true),
+            })
+        })
+        .collect::<Vec<_>>();
+    windows.sort_by(|left, right| {
+        left.panel
+            .cmp(&right.panel)
+            .then(left.label.cmp(&right.label))
+    });
+    windows
+}
+
 /// `open_view_window` — open or focus a detached OS window for one panel.
 ///
 /// The window is a normal decorated, resizable system window. Its webview loads
@@ -2578,6 +2627,42 @@ mod view_window_tests {
         assert!(err.message.contains("invalid view panel: terminal"));
     }
 
+    #[test]
+    fn view_window_label_parser_accepts_stable_and_legacy_labels() {
+        assert_eq!(
+            view_panel_from_window_label("view-tickets")
+                .unwrap()
+                .as_str(),
+            "tickets"
+        );
+        assert_eq!(
+            view_panel_from_window_label("view-tickets-0000000000000000000000000000002a")
+                .unwrap()
+                .as_str(),
+            "tickets"
+        );
+        assert!(view_panel_from_window_label("main").is_none());
+        assert!(view_panel_from_window_label("view-unknown").is_none());
+        assert!(view_panel_from_window_label("view-tickets-not-a-project").is_none());
+    }
+
+    #[test]
+    fn view_window_snapshot_payload_is_camel_case() {
+        let payload = ViewWindowSnapshot {
+            panel: "tickets".to_owned(),
+            label: "view-tickets".to_owned(),
+            visible: true,
+        };
+
+        let json = serde_json::to_string(&payload).unwrap();
+        assert!(json.contains("\"panel\":\"tickets\""), "json was {json}");
+        assert!(
+            json.contains("\"label\":\"view-tickets\""),
+            "json was {json}"
+        );
+        assert!(json.contains("\"visible\":true"), "json was {json}");
+    }
+
     #[test]
     fn view_window_lifecycle_payload_is_camel_case() {
         let payload = ViewWindowLifecycleEventDto {

crates/app-tauri/src/lib.rs

@@ -264,6 +264,7 @@ pub fn run() {
             commands::resolve_memory_links,
             commands::set_focused_project,
             commands::get_focused_project,
+            commands::list_open_view_windows,
             commands::open_view_window,
             commands::close_view_window,
             commands::move_tab_to_new_window,

frontend/src/adapters/mock/index.ts

@@ -90,6 +90,7 @@ import type {
   UpdateTicketInput,
   UiPreferencesGateway,
   ViewWindowClosed,
+  ViewWindowSnapshot,
   WindowGateway,
   FocusedProject,
   FocusedProjectGateway,
@@ -1118,6 +1119,16 @@ export class MockWindowGateway implements WindowGateway {
     }
   }
 
+  async listOpenViewWindows(): Promise<ViewWindowSnapshot[]> {
+    // Mirror the backend enumeration: every currently-open detached window is
+    // reported visible, with a stable label derived from its panel id.
+    return [...this.open].map((panel) => ({
+      panel,
+      label: panel,
+      visible: true,
+    }));
+  }
+
   async onViewWindowClosed(
     handler: (event: ViewWindowClosed) => void,
   ): Promise<Unsubscribe> {

frontend/src/adapters/window.ts

@@ -14,7 +14,11 @@ import { invoke } from "@tauri-apps/api/core";
 import { listen } from "@tauri-apps/api/event";
 
 import type { Unsubscribe } from "@/domain";
-import type { ViewWindowClosed, WindowGateway } from "@/ports";
+import type {
+  ViewWindowClosed,
+  ViewWindowSnapshot,
+  WindowGateway,
+} from "@/ports";
 
 /** The single Tauri event carrying detached-window lifecycle transitions. */
 const VIEW_WINDOW_LIFECYCLE = "view-window://lifecycle";
@@ -41,6 +45,12 @@ export class TauriWindowGateway implements WindowGateway {
     await invoke("close_view_window", { panel });
   }
 
+  async listOpenViewWindows(): Promise<ViewWindowSnapshot[]> {
+    // Backend serialises the snapshots in camelCase (panel/label/visible), so the
+    // wire shape matches the port type directly.
+    return invoke<ViewWindowSnapshot[]>("list_open_view_windows");
+  }
+
   async onViewWindowClosed(
     handler: (event: ViewWindowClosed) => void,
   ): Promise<Unsubscribe> {

frontend/src/features/projects/ProjectsView.reconcile.test.tsx

@@ -0,0 +1,98 @@
+/**
+ * #50 — at mount, `ProjectsView` reconciles its `placements` with the detached
+ * view windows already open at the OS level (a panel-only window restored by the
+ * OS before the main window mounted). Without this, the Panneaux menu would show
+ * such a window as « Fermé ». This exercises the wiring end-to-end through the
+ * {@link WindowGateway}; the reconciliation invariants themselves are unit-tested
+ * in `viewPlacement.test.ts`.
+ */
+import { describe, it, expect } from "vitest";
+import {
+  render,
+  screen,
+  within,
+  waitFor,
+  fireEvent,
+} from "@testing-library/react";
+
+import {
+  MockAgentGateway,
+  MockGitGateway,
+  MockProfileGateway,
+  MockFocusedProjectGateway,
+  MockProjectGateway,
+  MockSystemGateway,
+  MockTemplateGateway,
+  MockWindowGateway,
+  MockWorkStateGateway,
+} from "@/adapters/mock";
+import type { Gateways, WindowGateway } from "@/ports";
+import { DIProvider } from "@/app/di";
+import { ProjectsView } from "./ProjectsView";
+
+async function renderWith(windowGateway: WindowGateway) {
+  const project = new MockProjectGateway();
+  await project.createProject("alpha", "/p/a");
+  const agentGateway = new MockAgentGateway();
+  const gateways = {
+    system: new MockSystemGateway(),
+    project,
+    agent: agentGateway,
+    profile: new MockProfileGateway(),
+    template: new MockTemplateGateway(agentGateway),
+    git: new MockGitGateway(),
+    workState: new MockWorkStateGateway(),
+    window: windowGateway,
+    focusedProject: new MockFocusedProjectGateway(),
+  } as unknown as Gateways;
+  render(
+    <DIProvider gateways={gateways}>
+      <ProjectsView />
+    </DIProvider>,
+  );
+  fireEvent.click(await screen.findByRole("button", { name: "Open" }));
+  await waitFor(() =>
+    expect(
+      within(screen.getByRole("tablist")).getAllByRole("tab"),
+    ).toHaveLength(1),
+  );
+}
+
+/** Opens « Panneaux → Git » and returns the « Fenêtre détachée » submenu leaf. */
+function openGitDetachedLeaf() {
+  fireEvent.click(screen.getByRole("button", { name: "Panneaux" }));
+  fireEvent.click(screen.getByRole("button", { name: "Git" }));
+  return screen.getByRole("button", { name: "Fenêtre détachée" });
+}
+
+describe("ProjectsView startup reconciliation (#50)", () => {
+  it("marks an already-open detached window as « détaché » at mount", async () => {
+    const windowGateway = new MockWindowGateway();
+    // A panel-only Git window is already open at the OS level before mount.
+    windowGateway.open.add("git");
+
+    await renderWith(windowGateway);
+
+    // The « Fenêtre détachée » leaf reads ACTIVE (●) — not « Fermé ».
+    await waitFor(() =>
+      expect(openGitDetachedLeaf().textContent).toContain("●"),
+    );
+  });
+
+  it("does not reconcile when enumeration fails (no ghost detached slot)", async () => {
+    const windowGateway = new MockWindowGateway();
+    windowGateway.listOpenViewWindows = () =>
+      Promise.reject(new Error("boom"));
+
+    await renderWith(windowGateway);
+
+    // Git stays « Fermé »: the detached leaf is not active.
+    fireEvent.click(screen.getByRole("button", { name: "Panneaux" }));
+    fireEvent.click(screen.getByRole("button", { name: "Git" }));
+    await waitFor(() =>
+      expect(
+        screen.getByRole("button", { name: "Fenêtre détachée" }).textContent,
+      ).not.toContain("●"),
+    );
+  });
+});

frontend/src/features/projects/ProjectsView.tsx

@@ -61,6 +61,7 @@ import {
   isDockedTo,
   panelsDockedTo,
   placementOf,
+  reconcileDetachedWindows,
   type PanelId,
   type ViewPlacement,
   type ViewPlacements,
@@ -281,6 +282,31 @@ export function ProjectsView() {
     };
   }, [windowGateway]);
 
+  // On mount, reconcile `placements` with detached windows already open at the
+  // OS level (#50): a panel-only window restored by the OS before the main
+  // window mounted is unknown to `placements`, so the Panneaux menu would wrongly
+  // show it "Fermé". Enumerate them once and mark each as "detached" — but only
+  // best-effort and without clobbering more specific state: skip non-visible
+  // snapshots, skip `projects`/unknown panels, and never overwrite a placement
+  // the user (or a UI restore) already set to something other than "closed". A
+  // failed enumeration leaves `placements` untouched (no ghost slots). Independent
+  // of `active`: a panel-only window can be open with no active project.
+  useEffect(() => {
+    let cancelled = false;
+    void windowGateway
+      .listOpenViewWindows()
+      .then((snapshots) => {
+        if (cancelled) return;
+        setPlacements((prev) => reconcileDetachedWindows(prev, snapshots));
+      })
+      .catch(() => {
+        /* best-effort only: no reconciliation on failure */
+      });
+    return () => {
+      cancelled = true;
+    };
+  }, [windowGateway]);
+
   // Opening a conversation viewer takes over the main area — dismiss floating
   // windows so they don't obscure the viewer (LS7). Docked views stay beside it.
   function openConversation(conversationId: string) {

frontend/src/features/projects/viewPlacement.test.ts

@@ -0,0 +1,89 @@
+/**
+ * #50 — startup reconciliation of `placements` with the detached view windows
+ * already open at the OS level. Unit-tests the pure `isDetachablePanel` guard
+ * and `reconcileDetachedWindows`, covering every Architect invariant:
+ * only-visible, known-detachable-only (projects/unknown excluded), and the
+ * no-clobber rule (never overwrite a non-closed placement).
+ */
+import { describe, it, expect } from "vitest";
+
+import type { ViewWindowSnapshot } from "@/ports";
+import {
+  isDetachablePanel,
+  reconcileDetachedWindows,
+  type ViewPlacements,
+} from "./viewPlacement";
+
+const snap = (
+  panel: string,
+  visible = true,
+): ViewWindowSnapshot => ({ panel, label: panel, visible });
+
+describe("isDetachablePanel (#50)", () => {
+  it("accepts every known panel except projects", () => {
+    expect(isDetachablePanel("git")).toBe(true);
+    expect(isDetachablePanel("tickets")).toBe(true);
+    expect(isDetachablePanel("memory")).toBe(true);
+  });
+
+  it("excludes projects (main-window-only chrome) and unknown panels", () => {
+    expect(isDetachablePanel("projects")).toBe(false);
+    expect(isDetachablePanel("bogus")).toBe(false);
+    expect(isDetachablePanel("")).toBe(false);
+  });
+});
+
+describe("reconcileDetachedWindows (#50)", () => {
+  it("marks a visible detachable snapshot as detached from an empty state", () => {
+    const next = reconcileDetachedWindows({}, [snap("git")]);
+    expect(next).toEqual({ git: "detached" });
+  });
+
+  it("reconciles several panels at once", () => {
+    const next = reconcileDetachedWindows({}, [snap("git"), snap("tickets")]);
+    expect(next).toEqual({ git: "detached", tickets: "detached" });
+  });
+
+  it("ignores non-visible snapshots", () => {
+    const prev: ViewPlacements = {};
+    const next = reconcileDetachedWindows(prev, [snap("git", false)]);
+    expect(next).toBe(prev); // referentially unchanged
+  });
+
+  it("excludes the projects panel", () => {
+    const prev: ViewPlacements = {};
+    const next = reconcileDetachedWindows(prev, [snap("projects")]);
+    expect(next).toBe(prev);
+  });
+
+  it("ignores unknown panel ids", () => {
+    const prev: ViewPlacements = {};
+    const next = reconcileDetachedWindows(prev, [snap("bogus")]);
+    expect(next).toBe(prev);
+  });
+
+  it("never clobbers a non-closed placement (floating/dock/detached preserved)", () => {
+    const prev: ViewPlacements = {
+      git: "floating",
+      tickets: { dock: "left" },
+      memory: "detached",
+    };
+    const next = reconcileDetachedWindows(prev, [
+      snap("git"),
+      snap("tickets"),
+      snap("memory"),
+    ]);
+    expect(next).toBe(prev); // nothing changed → same reference
+  });
+
+  it("reconciles only the closed panels, leaving others intact", () => {
+    const prev: ViewPlacements = { git: "floating" };
+    const next = reconcileDetachedWindows(prev, [snap("git"), snap("agents")]);
+    expect(next).toEqual({ git: "floating", agents: "detached" });
+  });
+
+  it("returns the same reference when there is nothing to reconcile", () => {
+    const prev: ViewPlacements = {};
+    expect(reconcileDetachedWindows(prev, [])).toBe(prev);
+  });
+});

frontend/src/features/projects/viewPlacement.ts

@@ -17,6 +17,7 @@
  */
 
 import type { DockSide } from "@/shared";
+import type { ViewWindowSnapshot } from "@/ports";
 
 /** A panel reachable from the menu bar. */
 export type PanelId =
@@ -95,3 +96,44 @@ export function floatingPanels(placements: ViewPlacements): PanelId[] {
 export function isDetached(placement: ViewPlacement): boolean {
   return placement === "detached";
 }
+
+/**
+ * True when `panel` is a known, detachable {@link PanelId} — every panel except
+ * `projects`, which is main-window-only chrome (its submenu never offers the
+ * detached-window action). Used by the startup reconciliation (#50) to accept
+ * only detachable panels from a `ViewWindowSnapshot`: `projects` is excluded and
+ * any unknown panel string is ignored.
+ */
+export function isDetachablePanel(panel: string): boolean {
+  return panel !== "projects" && panel in PANEL_TITLE;
+}
+
+/**
+ * Reconcile `prev` placements with the detached windows already open at the OS
+ * level (#50), returning the merged placements — or `prev` unchanged when there
+ * is nothing to reconcile (referential-stability so a React setter is a no-op).
+ *
+ * Strict, best-effort merge honouring the Architect invariants:
+ *  - only `visible === true` snapshots are considered;
+ *  - only known detachable panels — `projects` and unknown panel strings are
+ *    dropped ({@link isDetachablePanel});
+ *  - a panel is set to `"detached"` **only** when its current placement is
+ *    `"closed"`/absent — an existing `floating`/dock/`detached` is never
+ *    clobbered (no loss of user state or of a more specific UI restore).
+ */
+export function reconcileDetachedWindows(
+  prev: ViewPlacements,
+  snapshots: ViewWindowSnapshot[],
+): ViewPlacements {
+  let changed = false;
+  const next: ViewPlacements = { ...prev };
+  for (const item of snapshots) {
+    if (!item.visible) continue;
+    if (!isDetachablePanel(item.panel)) continue;
+    const panel = item.panel as PanelId;
+    if (placementOf(prev, panel) !== "closed") continue;
+    next[panel] = "detached";
+    changed = true;
+  }
+  return changed ? next : prev;
+}

frontend/src/ports/index.ts

@@ -947,6 +947,21 @@ export interface ViewWindowClosed {
   panel: string;
 }
 
+/**
+ * A snapshot of one detached view window currently open at the OS level
+ * (ticket #50). Enumerated at startup so the main window can reconcile its
+ * `placements` state with windows that were already open before it mounted (a
+ * panel-only window restored by the OS shows as "detached", not "closed").
+ *
+ * `panel` is a `PanelId`-shaped string (kept as `string` at the port seam);
+ * `visible` distinguishes a truly-open window from a tracked-but-hidden one.
+ */
+export interface ViewWindowSnapshot {
+  panel: string;
+  label: string;
+  visible: boolean;
+}
+
 /**
  * Detaching a View into its own OS window (ticket #23, reworked in #47).
  *
@@ -968,6 +983,14 @@ export interface WindowGateway {
   openViewWindow(panel: string): Promise<void>;
   /** Closes the detached window for `panel` if one is open. */
   closeViewWindow(panel: string): Promise<void>;
+  /**
+   * Lists the detached view windows currently open at the OS level (ticket #50).
+   * Called once at main-window mount to reconcile `placements` with windows that
+   * survived a restart / were opened before mount, so a panel-only window shows
+   * as "detached" rather than "closed" in the Panneaux menu. Best-effort: callers
+   * treat a rejection as "no reconciliation".
+   */
+  listOpenViewWindows(): Promise<ViewWindowSnapshot[]>;
   /**
    * Subscribes to detached-window close events (OS close or programmatic). The
    * handler receives the `{ panel }` that closed. Returns an unsubscribe.