feat(crawler): live status surface, runtime session, dead-job repo, auto-restart

Adds the in-process observability + control infrastructure the admin
dashboard consumes:

- status.rs: CrawlerStatus/Phase/WorkerState + StatusHandle. The daemon
  publishes its current phase (idle/walking/fetching-metadata/cover-backfill),
  per-worker activity, and last-pass summary. Wired through the cron,
  run_metadata_pass, and the worker loop.
- session_control.rs: SessionController refreshes PHPSESSID at runtime —
  rewrites the shared reqwest cookie jar, updates the value on_launch reads,
  persists to crawler_state (survives restart), and clears the expired flag.
  on_launch now reads the live session instead of a startup snapshot.
- RealChapterDispatcher auto-triggers a coordinated browser restart after
  CRAWLER_BROWSER_RESTART_THRESHOLD consecutive transient failures.
- repo::crawler: list_dead_jobs, requeue_dead_jobs (all/manga/job, bypassing
  the quarantine, skipping live duplicates), job_state_counts.
- AppState gains CrawlerControl bundling browser_manager + session + status
  + metadata_pass for the admin endpoints.

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

backend/tests/crawler_dead_jobs.rs

@@ -0,0 +1,171 @@
+//! Integration tests for the dead-letter admin queries in
+//! `repo::crawler`: listing dead jobs with manga/chapter context and the
+//! scoped requeue (all / per-manga / single) used by the admin dashboard.
+
+use mangalord::repo::crawler::{self, RequeueScope};
+use serde_json::json;
+use sqlx::PgPool;
+use uuid::Uuid;
+
+/// Seed a manga + chapter and return their ids.
+async fn seed_chapter(pool: &PgPool, title: &str, number: i32) -> (Uuid, Uuid) {
+    let manga_id = Uuid::new_v4();
+    let chapter_id = Uuid::new_v4();
+    sqlx::query("INSERT INTO mangas (id, title) VALUES ($1, $2)")
+        .bind(manga_id)
+        .bind(title)
+        .execute(pool)
+        .await
+        .unwrap();
+    sqlx::query("INSERT INTO chapters (id, manga_id, number) VALUES ($1, $2, $3)")
+        .bind(chapter_id)
+        .bind(manga_id)
+        .bind(number)
+        .execute(pool)
+        .await
+        .unwrap();
+    (manga_id, chapter_id)
+}
+
+/// Insert a crawler_jobs row in a given state for a chapter-content job.
+async fn insert_job(pool: &PgPool, chapter_id: Uuid, state: &str, attempts: i32) -> Uuid {
+    let id = Uuid::new_v4();
+    let payload = json!({
+        "kind": "sync_chapter_content",
+        "source_id": "target",
+        "chapter_id": chapter_id,
+        "source_chapter_key": "k",
+    });
+    sqlx::query(
+        "INSERT INTO crawler_jobs (id, payload, state, attempts, last_error) \
+         VALUES ($1, $2, $3, $4, 'boom')",
+    )
+    .bind(id)
+    .bind(payload)
+    .bind(state)
+    .bind(attempts)
+    .execute(pool)
+    .await
+    .unwrap();
+    id
+}
+
+async fn state_of(pool: &PgPool, id: Uuid) -> String {
+    sqlx::query_scalar::<_, String>("SELECT state FROM crawler_jobs WHERE id = $1")
+        .bind(id)
+        .fetch_one(pool)
+        .await
+        .unwrap()
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn list_dead_jobs_returns_context_and_total(pool: PgPool) {
+    let (_m, c1) = seed_chapter(&pool, "Naruto", 700).await;
+    insert_job(&pool, c1, "dead", 5).await;
+    // A non-dead job must not appear.
+    let (_m2, c2) = seed_chapter(&pool, "Bleach", 1).await;
+    insert_job(&pool, c2, "pending", 0).await;
+
+    let (items, total) = crawler::list_dead_jobs(&pool, None, 50, 0).await.unwrap();
+    assert_eq!(total, 1);
+    assert_eq!(items.len(), 1);
+    let row = &items[0];
+    assert_eq!(row.manga_title.as_deref(), Some("Naruto"));
+    assert_eq!(row.chapter_number, Some(700));
+    assert_eq!(row.attempts, 5);
+    assert_eq!(row.last_error.as_deref(), Some("boom"));
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn list_dead_jobs_filters_by_title_search(pool: PgPool) {
+    let (_m, c1) = seed_chapter(&pool, "Naruto", 700).await;
+    insert_job(&pool, c1, "dead", 5).await;
+    let (_m2, c2) = seed_chapter(&pool, "One Piece", 1).await;
+    insert_job(&pool, c2, "dead", 5).await;
+
+    let (items, total) = crawler::list_dead_jobs(&pool, Some("piece"), 50, 0)
+        .await
+        .unwrap();
+    assert_eq!(total, 1);
+    assert_eq!(items[0].manga_title.as_deref(), Some("One Piece"));
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn requeue_all_resets_dead_jobs_to_pending(pool: PgPool) {
+    let (_m, c1) = seed_chapter(&pool, "A", 1).await;
+    let (_m2, c2) = seed_chapter(&pool, "B", 1).await;
+    let j1 = insert_job(&pool, c1, "dead", 5).await;
+    let j2 = insert_job(&pool, c2, "dead", 5).await;
+
+    let n = crawler::requeue_dead_jobs(&pool, RequeueScope::All)
+        .await
+        .unwrap();
+    assert_eq!(n, 2);
+    assert_eq!(state_of(&pool, j1).await, "pending");
+    assert_eq!(state_of(&pool, j2).await, "pending");
+    let attempts: i32 = sqlx::query_scalar("SELECT attempts FROM crawler_jobs WHERE id = $1")
+        .bind(j1)
+        .fetch_one(&pool)
+        .await
+        .unwrap();
+    assert_eq!(attempts, 0, "attempts reset on requeue");
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn requeue_by_manga_scopes_to_that_manga(pool: PgPool) {
+    let (m1, c1) = seed_chapter(&pool, "A", 1).await;
+    let (_m2, c2) = seed_chapter(&pool, "B", 1).await;
+    let j1 = insert_job(&pool, c1, "dead", 5).await;
+    let j2 = insert_job(&pool, c2, "dead", 5).await;
+
+    let n = crawler::requeue_dead_jobs(&pool, RequeueScope::Manga(m1))
+        .await
+        .unwrap();
+    assert_eq!(n, 1);
+    assert_eq!(state_of(&pool, j1).await, "pending");
+    assert_eq!(state_of(&pool, j2).await, "dead", "other manga untouched");
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn requeue_single_job(pool: PgPool) {
+    let (_m, c1) = seed_chapter(&pool, "A", 1).await;
+    let (_m2, c2) = seed_chapter(&pool, "B", 1).await;
+    let j1 = insert_job(&pool, c1, "dead", 5).await;
+    let j2 = insert_job(&pool, c2, "dead", 5).await;
+
+    let n = crawler::requeue_dead_jobs(&pool, RequeueScope::Job(j1))
+        .await
+        .unwrap();
+    assert_eq!(n, 1);
+    assert_eq!(state_of(&pool, j1).await, "pending");
+    assert_eq!(state_of(&pool, j2).await, "dead");
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn requeue_skips_dead_when_live_job_exists_for_same_chapter(pool: PgPool) {
+    let (_m, c1) = seed_chapter(&pool, "A", 1).await;
+    let dead = insert_job(&pool, c1, "dead", 5).await;
+    // A live pending job for the SAME chapter already exists.
+    insert_job(&pool, c1, "pending", 0).await;
+
+    let n = crawler::requeue_dead_jobs(&pool, RequeueScope::All)
+        .await
+        .unwrap();
+    assert_eq!(n, 0, "must not resurrect a dead job that has a live counterpart");
+    assert_eq!(state_of(&pool, dead).await, "dead");
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn job_state_counts_groups_by_state(pool: PgPool) {
+    let (_m, c1) = seed_chapter(&pool, "A", 1).await;
+    let (_m2, c2) = seed_chapter(&pool, "B", 1).await;
+    let (_m3, c3) = seed_chapter(&pool, "C", 1).await;
+    insert_job(&pool, c1, "pending", 0).await;
+    insert_job(&pool, c2, "dead", 5).await;
+    insert_job(&pool, c3, "dead", 5).await;
+
+    let (pending, running, dead) = crawler::job_state_counts(&pool).await.unwrap();
+    assert_eq!(pending, 1);
+    assert_eq!(running, 0);
+    assert_eq!(dead, 2);
+}