feat(sprints): surface frontend du modèle de sprints

Ticket #10 — volet frontend des sprints.

- Domaine et ports frontend étendus au modèle de sprints (domain/index.ts,
  ports/index.ts).
- Adaptateurs : ticket.ts et mock/index.ts câblent les opérations sprints.
- UI tickets : useTickets + TicketsPanel exposent le rattachement/gestion des
  sprints, avec tests Vitest associés.

Typecheck / vitest / build verts.

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

frontend/src/features/tickets/useTickets.ts

@@ -5,22 +5,41 @@
  * `Issue*` domain events (via {@link SystemGateway}) to refresh the list on any
  * ticket mutation — including those made by agents through MCP. Filters/search
  * are part of the query and drive a re-fetch when they change.
+ *
+ * Sprints (ticket #10): the hook also loads the project's sprints so the panel
+ * can group tickets by sprint, and exposes `assignSprint` to move a ticket into
+ * or out of a sprint. Sprint lifecycle events refresh the sprint list.
  */
 
 import { useCallback, useEffect, useMemo, useState } from "react";
 
-import { isTicketEvent, type GatewayError, type Ticket, type TicketList } from "@/domain";
+import {
+  isSprintEvent,
+  isTicketEvent,
+  type GatewayError,
+  type Sprint,
+  type Ticket,
+  type TicketList,
+} from "@/domain";
 import type { CreateTicketInput, TicketListQuery } from "@/ports";
 import { useGateways } from "@/app/di";
 
 export interface TicketsViewModel {
   list: TicketList | null;
+  /** The project's sprints, ordered by `order` (ticket #10). */
+  sprints: Sprint[];
   error: string | null;
   busy: boolean;
   query: TicketListQuery;
   setQuery: (next: TicketListQuery) => void;
   refresh: () => Promise<void>;
   create: (input: CreateTicketInput) => Promise<Ticket | null>;
+  /**
+   * Assigns a ticket to a sprint (or clears it with `sprintId === null`). Reads
+   * the ticket's current version first so the summary-based list needs no
+   * version column. Refreshes on the resulting `issueSprintChanged` event.
+   */
+  assignSprint: (ref: string, sprintId: string | null) => Promise<boolean>;
 }
 
 function describe(e: unknown): string {
@@ -33,6 +52,7 @@ function describe(e: unknown): string {
 export function useTickets(projectId: string): TicketsViewModel {
   const { ticket, system } = useGateways();
   const [list, setList] = useState<TicketList | null>(null);
+  const [sprints, setSprints] = useState<Sprint[]>([]);
   const [error, setError] = useState<string | null>(null);
   const [busy, setBusy] = useState(false);
   const [query, setQuery] = useState<TicketListQuery>({});
@@ -55,6 +75,14 @@ export function useTickets(projectId: string): TicketsViewModel {
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [projectId, ticket, queryKey]);
 
+  const refreshSprints = useCallback(async () => {
+    try {
+      setSprints(await ticket.listSprints(projectId));
+    } catch (e) {
+      setError(describe(e));
+    }
+  }, [projectId, ticket]);
+
   const create = useCallback(
     async (input: CreateTicketInput): Promise<Ticket | null> => {
       setError(null);
@@ -70,10 +98,32 @@ export function useTickets(projectId: string): TicketsViewModel {
     [projectId, ticket, refresh],
   );
 
+  const assignSprint = useCallback(
+    async (ref: string, sprintId: string | null): Promise<boolean> => {
+      setError(null);
+      try {
+        const current = await ticket.read(projectId, ref);
+        await ticket.setTicketSprint(projectId, ref, sprintId, current.version);
+        // The `issueSprintChanged` event refreshes the list; refresh the sprint
+        // counts too (and update immediately in case events are not wired).
+        await Promise.all([refresh(), refreshSprints()]);
+        return true;
+      } catch (e) {
+        setError(describe(e));
+        return false;
+      }
+    },
+    [projectId, ticket, refresh, refreshSprints],
+  );
+
   useEffect(() => {
     void refresh();
   }, [refresh]);
 
+  useEffect(() => {
+    void refreshSprints();
+  }, [refreshSprints]);
+
   useEffect(() => {
     if (!system) return;
     let unsubscribe: (() => void) | undefined;
@@ -81,6 +131,11 @@ export function useTickets(projectId: string): TicketsViewModel {
     void system
       .onDomainEvent((event) => {
         if (isTicketEvent(event)) void refresh();
+        // Sprint membership (`issueSprintChanged`) and sprint lifecycle events
+        // both change the grouping → refresh the sprint list.
+        if (isSprintEvent(event) || event.type === "issueSprintChanged") {
+          void refreshSprints();
+        }
       })
       .then((u) => {
         if (cancelled) u();
@@ -90,7 +145,17 @@ export function useTickets(projectId: string): TicketsViewModel {
       cancelled = true;
       unsubscribe?.();
     };
-  }, [refresh, system]);
+  }, [refresh, refreshSprints, system]);
 
-  return { list, error, busy, query, setQuery, refresh, create };
+  return {
+    list,
+    sprints,
+    error,
+    busy,
+    query,
+    setQuery,
+    refresh,
+    create,
+    assignSprint,
+  };
 }