shareAI-lab/learn-claude-code · error · ValueError

Dependency not found: {dependency}

Error message

Dependency not found: {dependency}

What it means

Raised by TaskStore.create() in s10_task_system/code.py:109 when a dependency listed in blocked_by does not exist as a task file in the store. Before creating a task, create() de-duplicates the blocked_by list and calls self.exists(dependency) for each entry, which resolves '{dependency}.json' under the store root. Any missing or malformed dependency ID aborts creation, preserving the invariant that blockedBy references are always live tasks.

Source

Thrown at s10_task_system/code.py:109

        root = self._root(create=create_root)
        path = (root / f"{task_id}.json").resolve()
        if not path.is_relative_to(root):
            raise ValueError(f"Invalid task ID: {task_id!r}")
        return path

    def exists(self, task_id: str) -> bool:
        return self._path(task_id).is_file()

    def create(self, subject: str, description: str = "",
               blocked_by: list[str] | None = None) -> Task:
        subject = subject.strip()
        if not subject:
            raise ValueError("Task subject cannot be empty")

        dependencies = list(dict.fromkeys(blocked_by or []))
        for dependency in dependencies:
            if not self.exists(dependency):
                raise ValueError(f"Dependency not found: {dependency}")

        self._root(create=True)
        for _ in range(100):
            task = Task(
                id=f"task_{secrets.token_hex(4)}",
                subject=subject,
                description=description,
                status="pending",
                owner=None,
                blockedBy=dependencies,
            )
            try:
                with self._path(task.id, create_root=True).open(
                    "x", encoding="utf-8"
                ) as handle:
                    json.dump(asdict(task), handle, indent=2)
                return task
            except FileExistsError:

View on GitHub (pinned to 985456f4ad)

Solutions

1. Verify each dependency with store.exists(dep) before create(), and drop or resolve missing ones explicitly.
2. Re-derive dependency IDs at runtime (e.g. look tasks up by subject with store.list()) instead of caching IDs across sessions.
3. If a referenced task vanished legitimately, recreate it first or create the new task without that dependency.

Example fix

# before
store.create('ship release', blocked_by=['task_deadbeef', 'task_00000000'])

# after
blocked = [d for d in ['task_deadbeef', 'task_00000000'] if store.exists(d)]
store.create('ship release', blocked_by=blocked)

def missing_deps(store, blocked_by):
    return [d for d in (blocked_by or []) if not store.exists(d)]

try:
    store.create(subject, blocked_by=deps)
except ValueError as e:
    if str(e).startswith('Dependency not found'):
        deps = [d for d in deps if store.exists(d)]
        store.create(subject, blocked_by=deps)
    else:
        raise

When it happens

Trigger: Calling store.create('x', blocked_by=['task_00000000']) when no such file exists; passing a dependency ID with a typo or wrong length; passing a bg_ or cron_ ID from a different subsystem; referencing a task that was deleted after you copied its ID. Note the dependency must also match the task_ ID pattern or exists() itself raises 'Invalid task ID'.

Common situations: Scripts that hardcode dependency IDs from a previous run in a fresh store; UIs offering a task picker fed by stale data; concurrent deletion racing with creation; multi-agent flows where one agent creates tasks referencing another agent's store.

Related errors

• Invalid task ID: {task_id!r}
• Task subject cannot be empty
• Invalid task status: {task.status}
• Dependency not found: {dependency}
• Dependency not found: {dependency}

AI-assisted analysis of shareAI-lab/learn-claude-code@985456f4ad (2026-08-14). Data as JSON: /api/errors/335ea65e617c1735. Report an issue: GitHub.