Runaway copilot-file-search thread consumes CPU and unbounded disk while session is idle

Version: GitHub Copilot CLI 1.0.83-3 on Ubuntu 24.04

Summary

While a copilot --yolo session reports its status as idle, an internal copilot-file-search thread can continue running indefinitely, pinning a CPU core and writing an unbounded per-process diagnostic log under ~/.copilot/logs/ until the disk fills to 100%.

Observed behavior

• The session's foreground process stays alive and its reported status is idle, but the process is not actually idle at the OS level.
• The internal copilot-file-search thread crawls/indexes the working directory at ~50% CPU and does not stop on its own.
• The per-process diagnostic log in ~/.copilot/logs/ grows continuously — observed rates around 8 MiB per 10 seconds — with no apparent size cap or rotation. Individual logs reached 6–22 GB before intervention.
• On large or deeply nested directory trees, the crawler appears to get stuck (repeated traversal, symlink-loop-like behavior) rather than completing and going quiet.

Impact

• Root filesystem exhaustion (reached 100% used in the worst case), which affects the whole machine, not just the session.
• Sustained CPU consumption for an ostensibly idle session.

Reproduced

Seen multiple times in a 24h span, all with the identical signature: idle status + active copilot-file-search thread + a continuously growing diagnostic log under ~/.copilot/logs/. Killing the process is the only thing that stops it; the log then has to be deleted manually to reclaim space.

Expected behavior

• File-search/indexing should terminate (or throttle) when the session is idle.
• The crawler should detect and break traversal loops instead of looping indefinitely.
• Diagnostic logs should be size-capped or rotated so a single session cannot exhaust the disk.

Start by reproducing the idle-session behavior and inspect the copilot-file-search activity alongside per-process files under ~/.copilot/logs/. Trace whether traversal repeats and whether logging grows without bounds. Done means idle sessions stop or throttle indexing, traversal loops terminate, and diagnostic logs are capped or rotated.