[BUG] Silent file write failure — Claude claims to write files but never creates them (cross-surface, cross-account)

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?

Claude Code completes research and planning phases normally (tool calls execute, tokens are consumed), but when it attempts to write output files, it claims the file has been written while no file is ever created on the filesystem. No error message is returned. Tokens continue to be consumed.

When prompted to retry ("where is the document?", "can you please try again?"), Claude acknowledges the delay and says it's writing — but still produces no file. This cycle repeats indefinitely, burning tokens each time.

This is reproducible across two completely independent environments:

1. Claude Code CLI (v2.1.80) — enterprise/team API account
2. Claude.ai web interface (code execution / "create files" feature) — separate personal paid plan

Both on macOS. Two different accounts, two different billing arrangements, two different surfaces. This rules out local sandbox configuration, account-level permissions, and client-side bugs.

At least one other user has independently confirmed the same behavior today (March 20, 2026).

Observed behavior (CLI):

• Two explore agents complete successfully (54 tool uses / 78.6k tokens + 42 tool uses / 26.3k tokens)
• Claude says: "Excellent — I have a rich picture of both the workspace and n8n's capabilities. Now let me write the explainer document."
• Claude churns for 8m 55s with no output
• User: "Are you still churning?"
• Claude: "Nope — research is done. Writing the document now."
• Churns for 2m 3s — no file created
• User: "where is the document?"
• Claude: "Writing it now — apologies for the delay."
• Churns for 2m 3s — no file created
• User: "can you please try again?"
• Claude: "On it."
• Churns for 2m 3s — no file created

What Should Happen?

Claude should create the file it claims to be writing, or return an error explaining why it cannot. Silent consumption of tokens with no file output and no error is the worst possible failure mode — it's indistinguishable from normal operation until the user manually checks the filesystem.

Error Messages/Logs

No error messages are returned. The CLI shows only the churn timer labels ("Churned for 8m 55s", "Churned for 2m 3s", "Cooked for 2m 3s", "Sautéed for 2m 3s") with no error output, no Write tool invocation visible, and no file created.

Steps to Reproduce

1. Start a Claude Code session on a project
2. Ask Claude to research a topic and then write a document based on findings
3. Claude completes research phase normally (explore agents finish, tool calls succeed, tokens consumed)
4. Claude states it will now write the output document
5. Claude churns indefinitely — no file is created
6. Prompt Claude to retry — it acknowledges and claims to be writing, but still no file
7. Repeat — file is never produced

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Worked as recently as earlier this week — exact version unknown

Claude Code Version

2.1.80

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Cross-surface: Also reproducible on claude.ai web code execution (separate personal paid account, same macOS machine)
Cross-account: Enterprise/team API account (CLI) + personal paid plan (web) — both exhibit identical behavior
Second user confirmed: At least one other user independently experiencing the same silent write failure today
Status page shows all systems operational — this appears to be an undeclared degradation in the file-write / tool-execution layer
Possibly related: #36364 (sandbox bug, March 19), #13286 (similar silent write failure pattern), #5505 (lost file system write capability)

<img width="1136" height="651" alt="Image" src="https://github.com/user-attachments/assets/0bbade6b-fa32-4490-8c23-0ff6e933c9dc" />