Merge branch 'feature/issue-ticket-system' into feature/background-tasks-first-class

Intègre le système de tickets/issues V1 (validé QA vert de bout en bout,
mémoire tickets-v1-e2e-validated-qa) dans la branche des tâches de fond.
Conflits résolus : app-tauri/state.rs, domain/events.rs, domain/lib.rs, domain/ports.rs.

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

frontend/src/ports/index.ts

@@ -41,6 +41,12 @@ import type {
   SkillScope,
   Template,
   TerminalSession,
+  Ticket,
+  TicketCarnet,
+  TicketLinkKind,
+  TicketList,
+  TicketPriority,
+  TicketStatus,
   TurnPage,
   Unsubscribe,
 } from "@/domain";
@@ -698,6 +704,98 @@ export interface ConversationGateway {
   ): Promise<TurnPage>;
 }
 
+/** Filter/search criteria for {@link TicketGateway.list}. */
+export interface TicketListQuery {
+  status?: TicketStatus;
+  priority?: TicketPriority;
+  assignedAgentId?: string;
+  /** Free-text match over title/description. */
+  text?: string;
+  limit?: number;
+  cursor?: string;
+}
+
+/** Input for {@link TicketGateway.create}. */
+export interface CreateTicketInput {
+  title: string;
+  description?: string;
+  priority?: TicketPriority;
+  status?: TicketStatus;
+  assignedAgentIds?: string[];
+}
+
+/**
+ * Fields to change on {@link TicketGateway.update}. Only the provided keys are
+ * touched; `expectedVersion` is mandatory (optimistic concurrency — a stale
+ * value surfaces a `versionConflict` {@link GatewayError}).
+ */
+export interface UpdateTicketInput {
+  title?: string;
+  description?: string;
+  status?: TicketStatus;
+  priority?: TicketPriority;
+  assignedAgentIds?: string[];
+  expectedVersion: number;
+}
+
+/**
+ * Ticket gateway (public wire name for the backend `Issue` model). The only
+ * frontend place that knows the `ticket_*` command names; features consume this
+ * port through DI. Every mutation carries an `expectedVersion` and rejects with
+ * a `versionConflict` {@link GatewayError} when the ticket moved underneath.
+ */
+export interface TicketGateway {
+  /** Creates a ticket and returns it. */
+  create(projectId: string, input: CreateTicketInput): Promise<Ticket>;
+  /** Reads one ticket, optionally including its carnet body. */
+  read(
+    projectId: string,
+    ref: string,
+    includeCarnet?: boolean,
+  ): Promise<Ticket>;
+  /** Lists tickets matching the (optional) filter/search query. */
+  list(projectId: string, query?: TicketListQuery): Promise<TicketList>;
+  /** Applies partial edits (title/description/status/priority/assignees). */
+  update(
+    projectId: string,
+    ref: string,
+    input: UpdateTicketInput,
+  ): Promise<Ticket>;
+  /** Reads the ticket-scoped Markdown carnet. */
+  readCarnet(projectId: string, ref: string): Promise<TicketCarnet>;
+  /** Replaces (not appends) the ticket-scoped carnet body. */
+  updateCarnet(
+    projectId: string,
+    ref: string,
+    carnet: string,
+    expectedVersion: number,
+  ): Promise<Ticket>;
+  /** Links this ticket to another `#id` with the given relationship kind. */
+  link(
+    projectId: string,
+    ref: string,
+    targetRef: string,
+    kind: TicketLinkKind,
+    expectedVersion: number,
+  ): Promise<Ticket>;
+  /** Removes a link (optionally scoped to a single kind). */
+  unlink(
+    projectId: string,
+    ref: string,
+    targetRef: string,
+    expectedVersion: number,
+    kind?: TicketLinkKind,
+  ): Promise<Ticket>;
+  /** Assigns/unassigns an agent to the ticket. */
+  assign(
+    projectId: string,
+    ref: string,
+    agentId: string,
+    assigned: boolean,
+    expectedVersion: number,
+  ): Promise<Ticket>;
+}
+
 /**
  * The full set of gateways the app depends on, injected via the DI provider.
  * The composition (real vs mock) is chosen in `app/`.
@@ -719,4 +817,5 @@ export interface Gateways {
   permission: PermissionGateway;
   workState: WorkStateGateway;
   conversation: ConversationGateway;
+  ticket: TicketGateway;
 }