Dart Lifecycle Disposed Flag Overload

What it does

When your agent uses it

• A repository/service/controller has startListening/stopListening
• Subscribe/unsubscribe
• Similar lifecycle methods
• Re-opening the service after closing it appears to do nothing — no subscription

Example prompts

• “in the middle of tearing down this instance forever”
• “currently stopped, can be re-started”
• “/dart-lifecycle-disposed-flag-overload”

Workflow steps

2 steps, taken from the first numbered list in SKILL.md.

1. 1"This instance is permanently torn down" (e.g. user switched accounts, object
2. 2"Currently not listening, but could be re-started" (e.g. user navigated away

What it can do on your machine

Read from SKILL.md and the folder at commit c3d6f7e. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are dart).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • api.dart.dev
  • api.flutter.dev

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Dart Lifecycle Disposed Flag Overload loads about 2k tokens when it runs. Until then it costs about 225 tokens; SKILL.md has 658 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~225

When it runs · the whole SKILL.md, loaded when a task matches

~2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from divinevideo/divine-mobile at commit c3d6f7e, republished under its MPL-2.0 licence (© divinevideo). 658 words, ~1,955 tokens.

name

dart-lifecycle-disposed-flag-overload

description

Fix Dart/Flutter services where calling start() after stop() is a silent no-op because stop() sets a _disposed (or similar) flag that start()'s guard short-circuits on. Use when: (1) A repository/service/controller has startListening/stopListening, subscribe/unsubscribe, open/close, or similar lifecycle methods, (2) Re-opening the service after closing it appears to do nothing — no subscription, no events, no error, (3) Unit tests that only exercise a single mount/open/start cycle pass while the real app breaks on the second visit to a screen, (4) A boolean flag is used both for "in the middle of tearing down this instance forever" AND for "currently stopped, can be re-started". Common in Riverpod/Bloc-driven screens that wire startListening() in initState and stopListening() in dispose — the second time the user visits the screen, nothing happens.

author

Claude Code

version

1.0.0

date

2026-04-05

class MyRepository {
  bool _disposed = false;
  StreamSubscription<Event>? _subscription;

  void startListening() {
    if (_subscription != null || _disposed || !isInitialized) return;
    _subscription = _client.subscribe(...).listen(...);
  }

  Future<void> stopListening() async {
    _disposed = true;                    // ← THE BUG
    await _subscription?.cancel();
    _subscription = null;
  }

  void _resetState() {
    _disposed = true;
    // ... wipe credentials ...
    _disposed = false;
  }
}

class MyRepository {
  bool _disposed = false;
  StreamSubscription<Event>? _subscription;

  void startListening() {
    // Guard still checks _disposed for the permanent-teardown case — that
    // window is only open during _resetState()'s synchronous body.
    if (_subscription != null || _disposed || !isInitialized) return;
    _subscription = _client.subscribe(...).listen(...);
  }

  Future<void> stopListening() async {
    // Do NOT set _disposed here — _disposed is reserved for _resetState()
    // (permanent teardown, e.g. user switch). Setting it would make a
    // subsequent startListening() call a silent no-op and break re-open
    // flows like "user leaves the screen and comes back later".
    await _subscription?.cancel();
    _subscription = null;
  }

  void _resetState() {
    _disposed = true;
    // ... wipe credentials, cancel subscription, etc. ...
    _disposed = false;
  }
}

© divinevideo, MPL-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/dart-lifecycle-disposed-flag-overload of divinevideo/divine-mobile.

Open the folder on GitHubat commit c3d6f7e