feat(tickets): persistance de l'édition d'un ticket côté frontend

Ticket #9 — l'édition d'un ticket (titre, corps, champs) est désormais
persistée depuis le détail : useTicketDetail porte l'état d'édition et le
flux de sauvegarde, TicketDetail expose l'UI d'édition/validation.

Tests Vitest tickets verts (13/13), typecheck et build OK.

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

frontend/src/features/tickets/tickets.test.tsx

@@ -227,6 +227,126 @@ describe("TicketsView", () => {
     );
   });
 
+  it("preserves an in-progress description edit across a priority change (#9)", async () => {
+    const t = await ticket.create(PROJECT_ID, { title: "Persisted" });
+    renderView(ticket, system, agent);
+
+    fireEvent.click(await screen.findByText("Persisted"));
+    const dialog = await screen.findByRole("dialog");
+
+    // Start editing the description WITHOUT saving.
+    const desc = within(dialog).getByLabelText("Description") as HTMLTextAreaElement;
+    fireEvent.change(desc, { target: { value: "draft in progress" } });
+    // Also edit the title to cover both draft fields.
+    const titleInput = within(dialog).getByLabelText("Title") as HTMLInputElement;
+    fireEvent.change(titleInput, { target: { value: "Persisted (wip)" } });
+
+    // Change the priority — an immediate-apply mutation that re-fetches the ticket
+    // and bumps its version. The unsaved draft must survive.
+    fireEvent.change(within(dialog).getByLabelText("ticket priority"), {
+      target: { value: "high" },
+    });
+
+    // The backend applied the priority bump…
+    await waitFor(async () => {
+      const fresh = await ticket.read(PROJECT_ID, t.ref);
+      expect(fresh.priority).toBe("high");
+      expect(fresh.version).toBe(2);
+    });
+
+    // …and the in-progress edits are still there (not reverted).
+    expect(
+      (within(dialog).getByLabelText("Description") as HTMLTextAreaElement).value,
+    ).toBe("draft in progress");
+    expect(
+      (within(dialog).getByLabelText("Title") as HTMLInputElement).value,
+    ).toBe("Persisted (wip)");
+    // The description was never persisted.
+    const persisted = await ticket.read(PROJECT_ID, t.ref);
+    expect(persisted.description).toBe("");
+  });
+
+  it("prompts before closing with unsaved changes, and closes directly when clean (#9)", async () => {
+    const t = await ticket.create(PROJECT_ID, { title: "CloseGuard" });
+    const onClose = vi.fn();
+    const gateways = { ticket, system, agent } as unknown as Gateways;
+    render(
+      <DIProvider gateways={gateways}>
+        <TicketDetail
+          projectId={PROJECT_ID}
+          ticketRef={t.ref}
+          onClose={onClose}
+          onOpenRef={() => {}}
+        />
+      </DIProvider>,
+    );
+
+    const detail = await screen.findByRole("dialog", { name: `ticket ${t.ref}` });
+
+    // Clean state → Close fires onClose directly, no confirmation dialog.
+    fireEvent.click(within(detail).getByText("Close"));
+    expect(onClose).toHaveBeenCalledTimes(1);
+    expect(screen.queryByRole("dialog", { name: "unsaved changes" })).toBeNull();
+
+    // Now make the draft dirty and try to close again.
+    fireEvent.change(within(detail).getByLabelText("Description"), {
+      target: { value: "unsaved body" },
+    });
+    fireEvent.click(within(detail).getByText("Close"));
+
+    // The confirmation appears and onClose was NOT called again.
+    const confirm = await screen.findByRole("dialog", { name: "unsaved changes" });
+    expect(onClose).toHaveBeenCalledTimes(1);
+
+    // "Annuler" dismisses the popup and keeps the editor open.
+    fireEvent.click(within(confirm).getByLabelText("cancel close"));
+    await waitFor(() =>
+      expect(screen.queryByRole("dialog", { name: "unsaved changes" })).toBeNull(),
+    );
+    expect(onClose).toHaveBeenCalledTimes(1);
+
+    // Re-open the confirmation and choose "Fermer sans sauvegarder".
+    fireEvent.click(within(detail).getByText("Close"));
+    const confirm2 = await screen.findByRole("dialog", { name: "unsaved changes" });
+    fireEvent.click(within(confirm2).getByLabelText("close without saving"));
+    expect(onClose).toHaveBeenCalledTimes(2);
+    // The unsaved description was discarded (never persisted).
+    const fresh = await ticket.read(PROJECT_ID, t.ref);
+    expect(fresh.description).toBe("");
+  });
+
+  it("saves unsaved changes then closes when choosing « Sauvegarder » (#9)", async () => {
+    const t = await ticket.create(PROJECT_ID, { title: "SaveOnClose" });
+    const onClose = vi.fn();
+    const gateways = { ticket, system, agent } as unknown as Gateways;
+    render(
+      <DIProvider gateways={gateways}>
+        <TicketDetail
+          projectId={PROJECT_ID}
+          ticketRef={t.ref}
+          onClose={onClose}
+          onOpenRef={() => {}}
+        />
+      </DIProvider>,
+    );
+
+    const detail = await screen.findByRole("dialog", { name: `ticket ${t.ref}` });
+    fireEvent.change(within(detail).getByLabelText("Description"), {
+      target: { value: "final body" },
+    });
+    fireEvent.click(within(detail).getByText("Close"));
+
+    const confirm = await screen.findByRole("dialog", { name: "unsaved changes" });
+    fireEvent.click(within(confirm).getByLabelText("save and close"));
+
+    // The change is persisted and the panel closes.
+    await waitFor(async () => {
+      const fresh = await ticket.read(PROJECT_ID, t.ref);
+      expect(fresh.description).toBe("final body");
+    });
+    await waitFor(() => expect(onClose).toHaveBeenCalledTimes(1));
+  });
+
   it("copies a delegation context prompt (F7)", async () => {
     const writeText = stubClipboard();
     const t = await ticket.create(PROJECT_ID, { title: "Delegate me" });