[BUG] Task list (TaskCreate/TaskList) not restored on --resume/--continue — task-list id resolves to a new runtime id

Environment

• Claude Code version: 2.1.207
• Platform: macOS (darwin 25.4.0), zsh
• Task system: the current TaskCreate/TaskList/TaskUpdate tools (not the deprecated TodoWrite)

Bug description

Tasks created with TaskCreate are not restored when a session is resumed with claude --resume or claude --continue. After resume, TaskList returns an empty list and task numbering restarts from #1, even though the original task files are still present on disk.

Steps to reproduce

1. Start a session, have Claude create a task via TaskCreate ("Test task").
2. Observe it persisted on disk: ~/.claude/tasks/session-<8-hex>/1.json.
3. Exit the session.
4. claude --resume <that-session> (or claude --continue).
5. Ask for the task list.

Expected: the task list from the resumed session is visible ("Test task" present).

Actual: the task list is empty; a newly created task lands in a different directory and gets id #1 again.

Diagnosis

Task lists are stored per list-id under ~/.claude/tasks/<list-id>/N.json. On resume, the conversation transcript correctly continues in the same ~/.claude/projects/<project>/<session-id>.jsonl, but the task-list id resolves to a new runtime id, so the session gets a fresh empty directory:

• Original session 9201ae0c-… wrote tasks to ~/.claude/tasks/session-9201ae0c/.
• After --resume, the same conversation wrote new tasks to ~/.claude/tasks/session-92efd67b/ (verified by creating a marker task and checking which directory received it).
• The old directory with the original tasks remains on disk, orphaned.

From the minified binary (2.1.207), the list id is resolved roughly as: CLAUDE_CODE_TASK_LIST_ID env var → team name → runtime session id. The env var works as a stable, shareable list id (verified: launching with CLAUDE_CODE_TASK_LIST_ID=test-list routes new tasks to ~/.claude/tasks/test-list/), but it is undocumented; the default session-derived fallback is what breaks resume continuity.

Expected behavior

Resuming a session should reattach the task list the session was using before exit (the harness even nudges the model about "existing tasks", which makes the silent reset more confusing). Alternatively/additionally, documenting CLAUDE_CODE_TASK_LIST_ID would give users a supported way to keep a task list across sessions.