feat(background): livraison auto au propriétaire + projection des tâches de fond dans le work-state (T1+T3)

T1 — Wake automatique du propriétaire à la complétion.
La complétion d'une tâche de fond est désormais livrée à l'agent
propriétaire dès que la session accepte l'envoi (wake.rs :
mark_completion_delivered au send accepté), via un drain de flux dédié
(structured.rs : drain_reply_stream_with_readiness). L'inbox médiée
enfile l'item sans démarrer de tour ni marquer l'agent busy
(input/mod.rs : enqueue FIFO silencieux). Régression couverte
(tests/agent_wake.rs, tests input/mod.rs).

T3 — Tâches de fond projetées dans le read-model du panneau Work.
AgentWorkState porte désormais background_tasks
(VO AgentBackgroundTaskState), alimenté par un builder best-effort
with_background_tasks(store) : union list_open_for_agent + dispatch des
completions non livrées par owner_agent_id, erreur store => Vec vide
(aucune régression live/busy/tickets). DTO Tauri backgroundTasks et
wiring du BackgroundTaskStore côté state.rs. Le frontend, déjà câblé,
affiche Cancel/Retry (mapping queued/waiting -> pending, tri sur
updatedAtMs). Borne V1 : une tâche terminale déjà livrée n'est plus
énumérable (Retry limité à la fenêtre non livrée).

Tests : cargo build --workspace OK ; cargo test -p application /
-p app-tauri / -p infrastructure verts ; frontend build + vitest verts.

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

crates/app-tauri/src/dto.rs

@@ -9,11 +9,12 @@
 use serde::{Deserialize, Serialize};
 
 use application::{
-    AgentTicketState, AppError, AttachLiveAgentOutput, ConversationPreviewStatus,
-    ConversationTurnWorkPreview, ConversationWorkSummary, CreateProjectInput, CreateProjectOutput,
-    GitGraphOutput, HealthInput, HealthReport, LayoutKind, ListProjectsOutput, LiveSessionKind,
-    LiveSessionSnapshot, OpenProjectOutput, ProjectWorkState, StopLiveAgentOutput,
-    TicketWorkSource, TicketWorkStatus, TurnPage, TurnSource, TurnView,
+    AgentBackgroundTaskState, AgentTicketState, AppError, AttachLiveAgentOutput,
+    BackgroundTaskKindLabel, ConversationPreviewStatus, ConversationTurnWorkPreview,
+    ConversationWorkSummary, CreateProjectInput, CreateProjectOutput, GitGraphOutput, HealthInput,
+    HealthReport, LayoutKind, ListProjectsOutput, LiveSessionKind, LiveSessionSnapshot,
+    OpenProjectOutput, ProjectWorkState, StopLiveAgentOutput, TicketWorkSource, TicketWorkStatus,
+    TurnPage, TurnSource, TurnView,
 };
 use domain::{AgentBusyState, PageCursor, PageDirection, Project, ProjectId, TurnRole};
 
@@ -1607,6 +1608,50 @@ impl From<AgentTicketState> for AgentTicketStateDto {
     }
 }
 
+/// One background task owned by an agent in the Work panel read model.
+#[derive(Debug, Clone, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct AgentBackgroundTaskStateDto {
+    /// Stable task id (UUID string).
+    pub task_id: String,
+    /// Kind discriminant.
+    pub kind: String,
+    /// Lifecycle state.
+    pub state: String,
+    /// Process exit code, when the terminal result carries one.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub exit_code: Option<i32>,
+    /// Human-readable summary / error / reason of the terminal result.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub summary: Option<String>,
+    /// Bounded stdout tail.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub stdout_tail: Option<String>,
+    /// Bounded stderr tail.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub stderr_tail: Option<String>,
+    /// Creation timestamp, epoch milliseconds.
+    pub created_at_ms: u64,
+    /// Last update timestamp, epoch milliseconds.
+    pub updated_at_ms: u64,
+}
+
+impl From<AgentBackgroundTaskState> for AgentBackgroundTaskStateDto {
+    fn from(task: AgentBackgroundTaskState) -> Self {
+        Self {
+            task_id: task.task_id.to_string(),
+            kind: background_kind_label_from_work_state(task.kind).to_owned(),
+            state: background_state_label(task.state).to_owned(),
+            exit_code: task.exit_code,
+            summary: task.summary,
+            stdout_tail: task.stdout_tail,
+            stderr_tail: task.stderr_tail,
+            created_at_ms: task.created_at_ms,
+            updated_at_ms: task.updated_at_ms,
+        }
+    }
+}
+
 /// One manifest agent's current live/busy state.
 #[derive(Debug, Clone, Serialize)]
 #[serde(rename_all = "camelCase")]
@@ -1623,6 +1668,8 @@ pub struct AgentWorkStateDto {
     pub busy: AgentBusyState,
     /// Pending/in-progress delegation tickets, in FIFO order.
     pub tickets: Vec<AgentTicketStateDto>,
+    /// Best-effort first-class background tasks owned by this agent.
+    pub background_tasks: Vec<AgentBackgroundTaskStateDto>,
 }
 
 /// How much of a [`ConversationWorkSummaryDto`] could be derived, best-effort.
@@ -1748,6 +1795,11 @@ impl From<ProjectWorkState> for ProjectWorkStateDto {
                         .into_iter()
                         .map(AgentTicketStateDto::from)
                         .collect(),
+                    background_tasks: agent
+                        .background_tasks
+                        .into_iter()
+                        .map(AgentBackgroundTaskStateDto::from)
+                        .collect(),
                 })
                 .collect(),
             conversations: state
@@ -2924,6 +2976,16 @@ fn background_kind_label(kind: &BackgroundTaskKind) -> &'static str {
     }
 }
 
+/// Kind discriminant string for a work-state [`BackgroundTaskKindLabel`].
+fn background_kind_label_from_work_state(kind: BackgroundTaskKindLabel) -> &'static str {
+    match kind {
+        BackgroundTaskKindLabel::Command => "command",
+        BackgroundTaskKindLabel::HeadlessRendezvous => "headlessRendezvous",
+        BackgroundTaskKindLabel::SessionResume => "sessionResume",
+        BackgroundTaskKindLabel::Maintenance => "maintenance",
+    }
+}
+
 /// Lifecycle state string for a [`BackgroundTaskState`].
 fn background_state_label(state: BackgroundTaskState) -> &'static str {
     match state {