[BUG] Writes Truncated SKILL.md to Disk While Internal Prompt is Complete

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?

Product: Cowork (desktop, Windows)
Version: Current as of May 2026
Severity: Medium — no data loss, but causes persistent incorrect state and wastes significant user time

Issue 2: update_scheduled_task Writes Truncated SKILL.md to Disk While Internal Prompt is Complete

What Should Happen?

Expected behavior: The SKILL.md file on disk matches the prompt stored internally and used when the task runs.

Actual behavior: The SKILL.md file on disk is truncated mid-content. The internal prompt used by the scheduler is complete and correct — the task runs as expected — but the file on disk ends partway through, often mid-sentence or mid-section, with no error or indication of truncation.

Error Messages/Logs

**How the discrepancy was confirmed:**

- A scheduled task (weekly pipeline audit) ran correctly, executing all agreed-upon workflow steps
- The corresponding SKILL.md file on disk ended at line 92 of what should have been ~300+ lines
- Diagnostic analysis based on the truncated file incorrectly concluded that multiple workflow steps were missing
- The task's actual run proved the internal prompt was complete

Steps to Reproduce

Steps to reproduce:

1. Update a scheduled task's prompt using the update_scheduled_task tool
2. In a later session, read the task's SKILL.md file from disk (e.g., via the Read tool or by opening the file directly)

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.7196.0 (2dbd78)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Impact:

The truncated file becomes a permanently misleading reference. Future sessions that read the file to audit, debug, or update the task will produce incorrect conclusions. The .scheduled folder is also mounted read-only, so the only path to correct the on-disk file is through the same tool that caused the truncation — creating a circular dependency with risk of overwriting a working internal prompt.

Workaround: None that doesn't carry risk of disrupting the working internal prompt. Current recommendation is to leave the task untouched and treat the SKILL.md file as unreliable.