feat(infra,app): store FS live-state + use cases (LS2)

Adapter d'infrastructure et use cases applicatifs du live-state agent.
- `FsLiveStateStore` : persistance fichier avec écriture atomique
  (write-temp + rename) pour éviter tout snapshot partiel/corrompu.
- Use cases `UpdateLiveState` / `GetLiveStateLean` + DTO « lean » (vue
  allégée, bornée pour l'injection/affichage).
- Rétention bornée côté store (TTL + max_n) au-dessus des invariants
  domaine (keyed last-writer-wins, prune).
- Garde-fou versionné : `.gitignore` exclut `.ideai/live-state.json`
  (snapshot runtime reconstruit, non versionné — contrairement à
  `.ideai/memory/`).

cargo test -p infrastructure -p application : 0 échec (dont 5 tests
live_state_store) ; cargo fmt --all --check : exit 0.

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

crates/infrastructure/tests/live_state_store.rs

@@ -0,0 +1,157 @@
+//! LS2 integration tests for [`FsLiveStateStore`] against a **real** temp
+//! directory (programme live-state).
+//!
+//! These lock the durable behaviour an in-memory double cannot prove:
+//! - round-trip `upsert`/`load` survives a fresh instance ("restart");
+//! - a missing file => empty `LiveState` (never an error);
+//! - the write is atomic (no `.tmp` residue left behind);
+//! - `upsert` is keyed last-writer-wins, persisted (no duplicate per agent);
+//! - `prune` (TTL + max_n) is persisted.
+//!
+//! Convention: a hand-rolled [`TempDir`] over the OS temp dir (calqué sur
+//! `conversation_log.rs`) — absolute path for `ProjectPath::new`, cleaned on drop.
+
+use std::path::PathBuf;
+
+use domain::live_state::{LiveEntry, WorkStatus};
+use domain::ports::LiveStateStore;
+use domain::project::ProjectPath;
+use domain::AgentId;
+use infrastructure::FsLiveStateStore;
+use uuid::Uuid;
+
+struct TempDir(PathBuf);
+impl TempDir {
+    fn new() -> Self {
+        let p = std::env::temp_dir().join(format!("idea-ls2-livestate-{}", Uuid::new_v4()));
+        std::fs::create_dir_all(&p).unwrap();
+        Self(p)
+    }
+    fn project_path(&self) -> ProjectPath {
+        ProjectPath::new(self.0.to_string_lossy().into_owned()).unwrap()
+    }
+    fn file_path(&self) -> PathBuf {
+        self.0.join(".ideai").join("live-state.json")
+    }
+    fn tmp_path(&self) -> PathBuf {
+        self.0.join(".ideai").join("live-state.json.tmp")
+    }
+}
+impl Drop for TempDir {
+    fn drop(&mut self) {
+        let _ = std::fs::remove_dir_all(&self.0);
+    }
+}
+
+fn aid(n: u128) -> AgentId {
+    AgentId::from_uuid(Uuid::from_u128(n))
+}
+
+fn entry(agent: u128, intent: &str, status: WorkStatus, updated_at_ms: u64) -> LiveEntry {
+    LiveEntry::new(aid(agent), None, intent, status, None, None, updated_at_ms).unwrap()
+}
+
+#[tokio::test]
+async fn missing_file_loads_empty_without_error() {
+    let tmp = TempDir::new();
+    let store = FsLiveStateStore::new(&tmp.project_path());
+
+    let state = store.load().await.unwrap();
+    assert!(state.entries.is_empty(), "no file ⇒ empty live-state");
+    // load() must not have created the file.
+    assert!(!tmp.file_path().exists(), "load does not write");
+}
+
+#[tokio::test]
+async fn upsert_round_trips_across_a_fresh_instance() {
+    let tmp = TempDir::new();
+    {
+        let store = FsLiveStateStore::new(&tmp.project_path());
+        store
+            .upsert(entry(1, "building", WorkStatus::Working, 100))
+            .await
+            .unwrap();
+    }
+    // A fresh instance on the same root relits the persisted row.
+    let store = FsLiveStateStore::new(&tmp.project_path());
+    let state = store.load().await.unwrap();
+    assert_eq!(state.entries.len(), 1);
+    assert_eq!(state.entries[0].intent, "building");
+    assert_eq!(state.entries[0].status, WorkStatus::Working);
+
+    // Persisted JSON is camelCase.
+    let raw = std::fs::read_to_string(tmp.file_path()).unwrap();
+    assert!(raw.contains("\"agentId\""), "camelCase on disk: {raw}");
+    assert!(raw.contains("\"updatedAtMs\""));
+}
+
+#[tokio::test]
+async fn write_is_atomic_no_tmp_residue() {
+    let tmp = TempDir::new();
+    let store = FsLiveStateStore::new(&tmp.project_path());
+    store
+        .upsert(entry(1, "a", WorkStatus::Working, 1))
+        .await
+        .unwrap();
+    store
+        .upsert(entry(2, "b", WorkStatus::Idle, 2))
+        .await
+        .unwrap();
+
+    assert!(tmp.file_path().exists(), "final file present");
+    assert!(
+        !tmp.tmp_path().exists(),
+        "tmp file must be renamed away, not left behind"
+    );
+}
+
+#[tokio::test]
+async fn upsert_is_last_writer_wins_persisted() {
+    let tmp = TempDir::new();
+    let store = FsLiveStateStore::new(&tmp.project_path());
+
+    store
+        .upsert(entry(1, "first", WorkStatus::Working, 1))
+        .await
+        .unwrap();
+    store
+        .upsert(entry(1, "second", WorkStatus::Blocked, 2))
+        .await
+        .unwrap();
+
+    let state = store.load().await.unwrap();
+    assert_eq!(state.entries.len(), 1, "same agent ⇒ one row, no duplicate");
+    assert_eq!(state.entries[0].intent, "second");
+    assert_eq!(state.entries[0].status, WorkStatus::Blocked);
+}
+
+#[tokio::test]
+async fn prune_ttl_and_max_n_persisted() {
+    let tmp = TempDir::new();
+    let store = FsLiveStateStore::new(&tmp.project_path());
+
+    // Three rows at t=10/20/30; now=50, ttl=35 ⇒ t=10 (age 40>35) dropped,
+    // t=20 (age 30) and t=30 (age 20) kept.
+    store
+        .upsert(entry(1, "old", WorkStatus::Idle, 10))
+        .await
+        .unwrap();
+    store
+        .upsert(entry(2, "mid", WorkStatus::Working, 20))
+        .await
+        .unwrap();
+    store
+        .upsert(entry(3, "new", WorkStatus::Working, 30))
+        .await
+        .unwrap();
+
+    store.prune(50, 35, 100).await.unwrap();
+    let after_ttl = store.load().await.unwrap();
+    assert_eq!(after_ttl.entries.len(), 2, "TTL dropped the oldest");
+
+    // Now bound to 1 ⇒ keep the most recent (t=30).
+    store.prune(50, 35, 1).await.unwrap();
+    let after_cap = store.load().await.unwrap();
+    assert_eq!(after_cap.entries.len(), 1);
+    assert_eq!(after_cap.entries[0].updated_at_ms, 30);
+}