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/domain/index.ts

@@ -124,8 +124,60 @@ export type DomainEvent =
        */
       source?: "mcp" | "file";
     }
+  | { type: "issueCreated"; issueId: string; issueRef: string }
+  | { type: "issueUpdated"; issueRef: string; version: number }
+  | {
+      type: "issueStatusChanged";
+      issueRef: string;
+      status: TicketStatus;
+      version: number;
+    }
+  | {
+      type: "issuePriorityChanged";
+      issueRef: string;
+      priority: TicketPriority;
+      version: number;
+    }
+  | { type: "issueCarnetUpdated"; issueRef: string; version: number }
+  | {
+      type: "issueLinked";
+      issueRef: string;
+      target: string;
+      kind: TicketLinkKind;
+      version: number;
+    }
+  | {
+      type: "issueUnlinked";
+      issueRef: string;
+      target: string;
+      kind: TicketLinkKind;
+      version: number;
+    }
+  | {
+      type: "issueAgentAssigned";
+      issueRef: string;
+      agentId: string;
+      version: number;
+    }
+  | {
+      type: "issueAgentUnassigned";
+      issueRef: string;
+      agentId: string;
+      version: number;
+    }
   | { type: "ptyOutput"; sessionId: string; bytes: number[] };
 
+/**
+ * Whether a domain event is one of the ticket (`Issue*`) events. A small helper
+ * so ticket view-models refresh on any ticket mutation without re-enumerating
+ * every variant at each call site.
+ */
+export function isTicketEvent(
+  event: DomainEvent,
+): event is Extract<DomainEvent, { type: `issue${string}` }> {
+  return event.type.startsWith("issue");
+}
+
 /** Where a project physically lives (mirror of the backend `RemoteRef`). */
 export type RemoteRef =
   | { kind: "local" }
@@ -757,3 +809,84 @@ export interface GitBranches {
   branches: string[];
   current: string | null;
 }
+
+// ---------------------------------------------------------------------------
+// Tickets (public wire name for the backend `Issue` model — "ticket" is the
+// user-visible term; all commands/DTOs/events speak `ticket`/`issue`). Mirrors
+// the `Ticket*Dto` shapes in `crates/app-tauri/src/tickets.rs` (camelCase).
+// ---------------------------------------------------------------------------
+
+/** A ticket reference on the wire, always `#<n>` (e.g. `"#42"`). */
+export type TicketRef = string;
+
+/** Lifecycle status of a ticket. */
+export type TicketStatus = "open" | "inProgress" | "QA" | "closed";
+
+/** Priority of a ticket. */
+export type TicketPriority = "low" | "medium" | "high" | "critical";
+
+/** The kind of relationship between two tickets. */
+export type TicketLinkKind =
+  | "relatesTo"
+  | "blocks"
+  | "blockedBy"
+  | "duplicates"
+  | "dependsOn";
+
+/** Who performed a ticket mutation (mirror of `TicketActorDto`, tagged `kind`). */
+export type TicketActor =
+  | { kind: "user" }
+  | { kind: "agent"; agentId: string }
+  | { kind: "system" };
+
+/** One directed link from a ticket to another (mirror of `TicketLinkDto`). */
+export interface TicketLink {
+  targetRef: TicketRef;
+  kind: TicketLinkKind;
+}
+
+/** The full ticket, as returned by `ticket_read`/`ticket_create`/… . */
+export interface Ticket {
+  id: string;
+  ref: TicketRef;
+  number: number;
+  title: string;
+  description: string;
+  status: TicketStatus;
+  priority: TicketPriority;
+  /** Present only when the ticket was read with `includeCarnet`. */
+  carnet?: string;
+  links: TicketLink[];
+  assignedAgentIds: string[];
+  createdBy: TicketActor;
+  updatedBy: TicketActor;
+  createdAt: number;
+  updatedAt: number;
+  /** Optimistic-concurrency version; echoed back as `expectedVersion` on writes. */
+  version: number;
+}
+
+/** A ticket summary row from `ticket_list` (mirror of `TicketSummaryDto`). */
+export interface TicketSummary {
+  ref: TicketRef;
+  path: string;
+  title: string;
+  status: TicketStatus;
+  priority: TicketPriority;
+  assignedAgentIds: string[];
+  updatedAt: number;
+}
+
+/** One page of ticket summaries (mirror of `TicketListDto`). */
+export interface TicketList {
+  items: TicketSummary[];
+  /** Opaque cursor for the next page, absent when the list is exhausted. */
+  nextCursor?: string;
+}
+
+/** The scoped-to-a-ticket Markdown carnet (mirror of `TicketCarnetDto`). */
+export interface TicketCarnet {
+  ref: TicketRef;
+  carnet: string;
+  version: number;
+}