fix(kanban): avoid fragile failure-column renames

hermes_cli/kanban_db.py

@@ -953,31 +953,29 @@ def _migrate_add_optional_columns(conn: sqlite3.Connection) -> None:
             "CREATE INDEX IF NOT EXISTS idx_tasks_idempotency "
             "ON tasks(idempotency_key)"
         )
-    # Legacy column rename: ``spawn_failures`` → ``consecutive_failures``
-    # and ``last_spawn_error`` → ``last_failure_error``. The counter was
-    # originally spawn-only; it's now unified across spawn/timeout/
-    # crash outcomes. Rename when only the legacy columns exist to
-    # preserve historical counter values across upgrades. Add fresh
-    # otherwise.
+    # Legacy column migration: ``spawn_failures`` → ``consecutive_failures``
+    # and ``last_spawn_error`` → ``last_failure_error``. Avoid
+    # ``ALTER TABLE ... RENAME COLUMN`` here: existing board DBs may have
+    # related schema objects from older Kanban builds, and SQLite reparses
+    # the whole schema during a rename. Adding/copying is more tolerant and
+    # still preserves the historical counter/error values.
     if "consecutive_failures" not in cols:
+        conn.execute(
+            "ALTER TABLE tasks ADD COLUMN consecutive_failures "
+            "INTEGER NOT NULL DEFAULT 0"
+        )
         if "spawn_failures" in cols:
             conn.execute(
-                "ALTER TABLE tasks RENAME COLUMN spawn_failures TO consecutive_failures"
-            )
-        else:
-            conn.execute(
-                "ALTER TABLE tasks ADD COLUMN consecutive_failures "
-                "INTEGER NOT NULL DEFAULT 0"
+                "UPDATE tasks SET consecutive_failures = COALESCE(spawn_failures, 0)"
             )
     if "worker_pid" not in cols:
         conn.execute("ALTER TABLE tasks ADD COLUMN worker_pid INTEGER")
     if "last_failure_error" not in cols:
+        conn.execute("ALTER TABLE tasks ADD COLUMN last_failure_error TEXT")
         if "last_spawn_error" in cols:
             conn.execute(
-                "ALTER TABLE tasks RENAME COLUMN last_spawn_error TO last_failure_error"
+                "UPDATE tasks SET last_failure_error = last_spawn_error"
             )
-        else:
-            conn.execute("ALTER TABLE tasks ADD COLUMN last_failure_error TEXT")
     if "max_runtime_seconds" not in cols:
         conn.execute("ALTER TABLE tasks ADD COLUMN max_runtime_seconds INTEGER")
     if "last_heartbeat_at" not in cols:

tests/hermes_cli/test_kanban_core_functionality.py

@@ -2648,6 +2648,78 @@ def test_legacy_db_without_skills_column_migrates(tmp_path):
     conn.close()
 
 
+def test_legacy_spawn_failure_columns_are_copied_not_renamed(tmp_path):
+    """Legacy failure counters survive migration without fragile column renames."""
+    import sqlite3
+    db_path = tmp_path / "legacy-failures.db"
+    conn = sqlite3.connect(str(db_path))
+    conn.row_factory = sqlite3.Row
+    conn.execute("""
+        CREATE TABLE tasks (
+            id TEXT PRIMARY KEY,
+            title TEXT NOT NULL,
+            body TEXT,
+            assignee TEXT,
+            status TEXT NOT NULL,
+            priority INTEGER DEFAULT 0,
+            created_by TEXT,
+            created_at INTEGER NOT NULL,
+            started_at INTEGER,
+            completed_at INTEGER,
+            workspace_kind TEXT NOT NULL DEFAULT 'scratch',
+            workspace_path TEXT,
+            claim_lock TEXT,
+            claim_expires INTEGER,
+            tenant TEXT,
+            result TEXT,
+            idempotency_key TEXT,
+            spawn_failures INTEGER NOT NULL DEFAULT 0,
+            worker_pid INTEGER,
+            last_spawn_error TEXT
+        )
+    """)
+    conn.execute("""
+        CREATE TABLE task_events (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            task_id TEXT NOT NULL,
+            kind TEXT NOT NULL,
+            payload TEXT,
+            created_at INTEGER NOT NULL
+        )
+    """)
+    conn.execute(
+        "INSERT INTO tasks "
+        "(id, title, body, assignee, status, priority, created_by, created_at, "
+        "started_at, completed_at, workspace_kind, workspace_path, claim_lock, "
+        "claim_expires, tenant, result, idempotency_key, spawn_failures, "
+        "worker_pid, last_spawn_error) "
+        "VALUES ('legacy', 'old task', NULL, 'default', 'ready', 0, NULL, 1, "
+        "NULL, NULL, 'scratch', NULL, NULL, NULL, NULL, NULL, NULL, 4, NULL, "
+        "'missing profile')"
+    )
+    conn.commit()
+
+    kb._migrate_add_optional_columns(conn)
+    cols = {r[1] for r in conn.execute("PRAGMA table_info(tasks)")}
+    assert "spawn_failures" in cols
+    assert "consecutive_failures" in cols
+    assert "last_spawn_error" in cols
+    assert "last_failure_error" in cols
+
+    row = conn.execute("SELECT * FROM tasks WHERE id = 'legacy'").fetchone()
+    assert row["consecutive_failures"] == 4
+    assert row["last_failure_error"] == "missing profile"
+    task = kb.Task.from_row(row)
+    assert task.consecutive_failures == 4
+    assert task.last_failure_error == "missing profile"
+
+    kb._migrate_add_optional_columns(conn)
+    row_again = conn.execute("SELECT * FROM tasks WHERE id = 'legacy'").fetchone()
+    assert row_again["consecutive_failures"] == 4
+    assert row_again["last_failure_error"] == "missing profile"
+    conn.close()
+
+
 
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