Cowork: Project-bound scheduled tasks fail to spawn ("Failed to run scheduled task")

Summary

In Claude Desktop (Cowork, macOS), any local scheduled task that carries a Project binding fails to run. "Run now" shows the toast "Failed to run scheduled task. You can try again." Scheduled fires show "Skipped" in History. No session or transcript is ever created. The identical prompt created with no Project binding runs normally.

Environment

• macOS 26 (Darwin 25.6.0), Claude Desktop, Cowork, Max plan
• Local scheduled tasks (stored under ~/Documents/Claude/Scheduled/)
• Observed Sep 23 to 25, 2026

Steps to reproduce

1. Open a Cowork chat that is inside any Project.
2. Ask Claude to create a scheduled task (it calls create_scheduled_task). The task page shows Project = that project, Folders "(from project ...)", badge "Only on this computer."
3. Click Run now.

Result: toast "Failed to run scheduled task. You can try again." No session opens. If the task has a cron schedule, each fire is recorded as "Skipped."

Control: create the same task from Scheduled > New task > Set up manually, leave Project empty, grant one folder. Badge reads "Requires your computer." Run now succeeds and scheduled fires run.

Evidence

• Minimal case: a manual-only task with Project A bound, prompt "Do not use any tools. Reply with exactly one line and stop." No tools, no browser, no file access. Run now fails. This isolates the Project binding; nothing in the prompt can be at fault.
• Task X (Canvas monitoring, Chrome + one local folder): Project A bound, one inherited folder. Scheduled fire Sep 24: Skipped. Run now Sep 25: fails.
• Task X-2: same prompt, no Project, same single folder granted directly. Ran Sep 23 (manual), Sep 23 (scheduled), Sep 24 (scheduled), Sep 25 (manual). All succeeded.
• Two further tasks bound to Project B with three inherited folders: never spawned, Run now fails.
• Two tasks recreated via create_scheduled_task from a Project A chat: inherited Project A and four folders, Run now fails.
• Control group: about 20 tasks created July to September 2026 from chats with no Project ran on schedule through Sep 24.

Expected behavior

A Project-bound task runs like any other task; or create_scheduled_task exposes a way to create a task without inheriting the calling chat's Project; or the binding and its effect are documented. The help article "Schedule recurring tasks in Claude Cowork" describes both creation paths and does not mention Project binding.

Impact

Every task created conversationally from inside a Project (the primary way Cowork users create tasks) is dead on arrival. Scheduled fires fail silently as "Skipped," so the user does not learn the task never ran.

Workaround

Create tasks only from Scheduled > New task > Set up manually with Project empty, or from a chat that has no Project attached. Existing Project-bound tasks cannot be unbound through the tool; they must be recreated.