feat(db): add reset_running_tasks() for durable scheduler restart

scripts/db.py

@@ -366,6 +366,18 @@ def kill_stuck_tasks(db_path: Path = DEFAULT_DB) -> int:
     return count
 
 
+def reset_running_tasks(db_path: Path = DEFAULT_DB) -> int:
+    """On restart: mark in-flight tasks failed. Queued tasks survive for the scheduler."""
+    conn = sqlite3.connect(db_path)
+    count = conn.execute(
+        "UPDATE background_tasks SET status='failed', error='Interrupted by restart',"
+        " finished_at=datetime('now') WHERE status='running'"
+    ).rowcount
+    conn.commit()
+    conn.close()
+    return count
+
+
 def purge_email_data(db_path: Path = DEFAULT_DB) -> tuple[int, int]:
     """Delete all job_contacts rows and email-sourced pending jobs.
     Returns (contacts_deleted, jobs_deleted).

tests/test_task_scheduler.py

@@ -0,0 +1,58 @@
+# tests/test_task_scheduler.py
+"""Tests for scripts/task_scheduler.py and related db helpers."""
+import sqlite3
+import threading
+import time
+from collections import deque
+from pathlib import Path
+
+import pytest
+
+from scripts.db import init_db, reset_running_tasks
+
+
+@pytest.fixture
+def tmp_db(tmp_path):
+    db = tmp_path / "test.db"
+    init_db(db)
+    return db
+
+
+def test_reset_running_tasks_resets_only_running(tmp_db):
+    """reset_running_tasks() marks running→failed but leaves queued untouched."""
+    conn = sqlite3.connect(tmp_db)
+    conn.execute(
+        "INSERT INTO background_tasks (task_type, job_id, status) VALUES (?,?,?)",
+        ("cover_letter", 1, "running"),
+    )
+    conn.execute(
+        "INSERT INTO background_tasks (task_type, job_id, status) VALUES (?,?,?)",
+        ("company_research", 2, "queued"),
+    )
+    conn.commit()
+    conn.close()
+
+    count = reset_running_tasks(tmp_db)
+
+    conn = sqlite3.connect(tmp_db)
+    rows = {r[0]: r[1] for r in conn.execute(
+        "SELECT task_type, status FROM background_tasks"
+    ).fetchall()}
+    conn.close()
+
+    assert count == 1
+    assert rows["cover_letter"] == "failed"
+    assert rows["company_research"] == "queued"
+
+
+def test_reset_running_tasks_returns_zero_when_nothing_running(tmp_db):
+    """Returns 0 when no running tasks exist."""
+    conn = sqlite3.connect(tmp_db)
+    conn.execute(
+        "INSERT INTO background_tasks (task_type, job_id, status) VALUES (?,?,?)",
+        ("cover_letter", 1, "queued"),
+    )
+    conn.commit()
+    conn.close()
+
+    assert reset_running_tasks(tmp_db) == 0