fix(kanban): avoid fragile failure-column renames

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()
+
+
 
 # ---------------------------------------------------------------------------
 # Gateway-embedded dispatcher: config, CLI warnings, daemon deprecation stub