MCP server logs (stderr/stdout) are not rotated - can fill disk space

[piotrlo]

Pre-submit Checks

• I have searched Warp bugs and there are no duplicates
• I have searched Warp known issues page and my issue is not there
• I have an issue with AI and have included the debugging ID (Optional, but helps expedite the AI quality fix). Debugging ID instructions
• I have technical issue and have included the logs (optional, but helps expedite the bug fix). Log instructions

Describe the bug

Warp captures MCP server stderr/stdout to ~/Library/Group Containers/.../dev.warp.Warp-Stable/mcp/*.log but does NOT rotate these logs, unlike Warp's own logs in ~/Library/Logs/warp.log* which are properly rotated.

Result: Verbose MCP servers can fill disk space. In my case: 20GB in 5 days from iMCP heartbeat logging.

To reproduce

1. Add verbose MCP server (e.g., iMCP with debug logging)
2. Use Warp normally for several days
3. Check: du -sh ~/Library/Group\ Containers/2BBY89MBSN.dev.warp/Library/Application\ Support/dev.warp.Warp-Stable/mcp/
4. Observe unbounded log growth

Related: mattt/iMCP#105

Expected behavior

MCP logs should be rotated like Warp's own logs:

• Max file size (e.g., 100MB)
• Keep last N rotations (e.g., 5)
• Automatic cleanup
• Total directory size limit

Comparison:

• ✅ Warp logs: warp.log, warp.log.old.0, warp.log.old.1, etc. (rotated)
• ❌ MCP logs: No rotation → unbounded growth

Industry practice:

• VS Code rotates LSP server logs
• JetBrains IDEs limit external process logs

Screenshots, videos, and logs

No response

Operating system (OS)

macOS

Operating system and version

15.6.0

Shell Version

zsh 5.9 (arm64-apple-darwin24.0)

Current Warp version

v0.2025.10.01.08.12.stable_02

Regression

No, this bug or issue has existed throughout my experience using Warp

Recent working Warp date

No response

Additional context

Related Issues:

• iMCP verbose logging: Critical: DEBUG logging causes 20GB+ log file in 5 days due to heartbeat spam (no log rotation) mattt/iMCP#105 (being fixed on their side, but Warp should still handle unbounded logs gracefully)

Does this block you from using Warp daily?

Yes, this issue prevents me from using Warp daily.

Is this an issue only in Warp?

Yes, I confirmed that this only happens in Warp, not other terminals.

Warp Internal (ignore): linear-label:b9d78064-c89e-4973-b153-5178a31ee54e

None

[vorporeal]

@piotrlo - thanks for the report; I've forwarded it to the folks working on MCP improvements.

[martenzi]

Please fix this as it leads to almost crashing mac system where logs on 40+ gb eats internal drive. Ive symlinked to an external but its not sustainable.

[greenharry12]

Holy! I was confused why my Mac went from 120GB free space to completely full in 24 hours.

Turns out this issue caused Warp to write a 92GB log file from repeatedly failing to connect to an offline MCP server (Docker OAuth notifications). The log just kept growing with connection retry attempts.

File: ~/Library/Group Containers/2BBY89MBSN.dev.warp/Library/Application Support/dev.warp.Warp-Stable/mcp/j4BpIFnm03oguA6NbBaQxZ.log

Log rotation would definitely help prevent this!!! This should be high priority as that's pretty ridiculous!

[peicodes]

Quick update! We added some log clearing functionality which should go live in the next stable build on Dec 4.

Logs will clear when:

• A server is started
• A server is deleted

I know this isn't true log rotation, but it should help with keeping the logs manageable without having to manually delete them. We'll be looking into a longer term fix where logs are rotated even when the server continues to run.