Cowork scheduled-tasks MCP: 3 issues with UNC/junction paths after storage migration

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Summary

After migrating Cowork scheduled-tasks storage from OneDrive to a network share (Pi5 SMB) via an NTFS junction on 2026-05-04, three behaviors became visible in the scheduled-tasks MCP. Filing as one issue because they share root cause (path-handling around UNC and junctions); split if preferred.

Environment

• Cowork (Claude desktop app), latest stable as of 2026-05-22
• Windows 11, Cowork scheduled-tasks storage migrated to UNC path via NTFS junction
• Junction: C:\Users\<user>\OneDrive\Documenten\Claude\Scheduled\ → \\<host>\<share>\cowork-scheduled\
• Two task-population states coexist in list_scheduled_tasks:
• Pre-migration tasks (created before 2026-05-04): path-string still contains the junction parent (C:\Users\...\OneDrive\...) but physical files live on the share
• Post-migration tasks (created after 2026-05-04): path-string is the resolved UNC (\\<host>\<share>\cowork-scheduled\<task>), because the cowork service runs as LocalSystem and cannot resolve a user-owned junction; it resolves to UNC on write

Bug 1 — No delete_scheduled_task tool

The MCP exposes create_scheduled_task, list_scheduled_tasks, and update_scheduled_task but no delete. The only way to remove a task is to delete the underlying SKILL.md from the filesystem, which then triggers Bug 3.

Expected: A delete_scheduled_task tool that removes both the file and the register entry atomically.

Actual: No delete tool; filesystem delete leaves a ghost in list_scheduled_tasks.

Bug 2 — update_scheduled_task fails with "path traversal detected" on UNC paths

Any task whose stored path begins with \\ (i.e. all post-migration tasks) cannot be updated via the MCP.

Repro:

1. Create a task via create_scheduled_task while Cowork scheduled-storage is configured as a UNC path (directly, or via a junction whose target is UNC).
2. Inspect list_scheduled_tasks and confirm the path string starts with \\.
3. Call update_scheduled_task on that task with any field change (e.g. cron expression).
4. Observe error: "path traversal detected".

Expected: UNC paths should be allowed; the leading \\ is part of standard Windows UNC syntax, not a traversal sequence.

Actual: The path validator appears to treat \\ as suspicious and rejects, making all post-migration tasks read-only via the MCP. Tasks with the junction-style path (pre-migration) remain updateable because the string starts with C:\.

Workaround used: Recreate the task (which overwrites the register entry). Inefficient for small changes such as a single cron-expression tweak.

Bug 3 — Filesystem delete of SKILL.md leaves a ghost in list_scheduled_tasks

After a manual filesystem delete of SKILL.md, the task continues to appear in list_scheduled_tasks with an empty description. For post-migration tasks (UNC path), the ghost is permanent because Bug 2 prevents setting enabled: false.

Expected: list_scheduled_tasks should reconcile against the filesystem and either omit orphaned register entries or surface them with an explicit orphaned: true flag so they can be ignored or cleaned up.

Actual: Ghost entries persist with no remediation path for UNC tasks.

Why these matter (use-case context)

We're building a local "expired one-time task cleanup" handler that detects ghosts based on fire-date < now and absence of corresponding SKILL.md. Because of Bug 2 and Bug 3, our handler can only clean the filesystem side; the register-side ghost is by-design unreachable from the MCP. Our handler therefore restricts itself to filesystem cleanup and surfaces register-ghosts as a digest warning. We'd prefer the MCP itself reconciled.

Suggested fix priorities (subjective)

1. Bug 2 (path validator) — single behavioral change, unblocks Bug 3 workaround
2. Bug 3 (orphan reconciliation) — improves correctness even when Bug 2 stands
3. Bug 1 (delete tool) — nice-to-have once Bug 2 is fixed (delete via update enabled:false becomes viable)

Happy to provide additional traces or path-string examples on request.

What Should Happen?

Each of the three issues described above has its own Expected/Actual section in the body. Compact summary:

1. delete_scheduled_task tool should exist as a sibling of create/list/update.
2. update_scheduled_task should accept paths starting with \\ (valid Windows UNC syntax), not flag them as path traversal.
3. list_scheduled_tasks should reconcile against the filesystem — either omit orphaned register entries or surface them with an explicit orphaned: true flag.

Error Messages/Logs

update_scheduled_task — error string returned by MCP:

  "path traversal detected"

(User-facing error from the MCP response; no stack trace available at this layer. The leading `\\` of standard Windows UNC paths is being misclassified as a traversal sequence.)

Steps to Reproduce

Steps below reproduce Bug 2 (most concrete, deterministic). Bugs 1 and 3 are behavioral observations against the same MCP, fully described in the main body above.

Bug 2 reproduction:

1. On Windows 11, configure Cowork scheduled-tasks storage as a path that resolves to UNC. This can be a direct UNC path, or an NTFS junction whose target is UNC. In our environment: C:\Users\<user>\OneDrive\Documenten\Claude\Scheduled\ is a junction with target \\<host>\<share>\cowork-scheduled\.

1. Call create_scheduled_task via the MCP with any valid task definition. Confirm it creates successfully.

1. Call list_scheduled_tasks and inspect the new task. Confirm its path field starts with \\ (UNC). This happens because the cowork service runs as LocalSystem and cannot resolve a user-owned junction, so it stores the resolved UNC.

1. Call update_scheduled_task on that task with any field change (e.g. change the cron expression).

1. Observe: MCP returns error "path traversal detected". Task remains unchanged.

Expected: update succeeds, just as it does for pre-migration tasks whose path string still begins with C:\.

Bugs 1 and 3 are observational (no error to capture) — see main body.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.146 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Context note for triager: this report is about the Cowork (Claude desktop app) scheduled-tasks MCP, not Claude Code CLI itself. Some template fields (Claude Code Version, Terminal/Shell, Regression status) are filled because the form requires them, but they aren't diagnostic for this bug — the issue lives in the MCP server's path-validation and register-reconciliation layers. If a more appropriate template or repo exists for Cowork MCP bugs, please redirect.

"Filing as one issue" (vs three separate) is deliberate: all three behaviors share a single root cause (path-handling around UNC paths and NTFS junctions on Windows after storage-relocation). Bug 3 (orphan reconciliation) is meaningfully harder to triage without Bug 2 (UNC validator) context, because Bug 2 is the reason workarounds for Bug 3 are unreachable. Happy to split into separate issues if you prefer — please let me know.