fix: exclude Chrome/CDP browser profiles from checkpoint snapshots

[Thomasp23]

Problem

When checkpoints.enabled: true, every write_file triggers a git add -A in the working directory before creating a snapshot. On Windows, Chrome locks its profile files (Cookies, GPUPersistentCache/cache.db, etc.) while running. The git add -A blocks indefinitely on these locked files, freezing write_file for minutes.

Relevant logs:

Git command failed: git add -A (rc=128)
error: open("chrome_cdp_profile/GPUPersistentCache/DawnGraphiteCache/.../cache.db"): Permission denied
error: open("agent-browser-chrome-.../Default/Network/Cookies"): Permission denied

Fix

Add chrome_cdp_profile/ and agent-browser-chrome-*/ to DEFAULT_EXCLUDES in checkpoint_manager.py. These directories are created by the browser automation tool and should never be checkpointed.

Testing

• Python syntax: OK
• Existing checkpoint tests: not run (no pytest on this Windows install)
• Manual verification: fix resolves the write_file freeze on a Windows machine with Chrome running and checkpoints.enabled: true

[teknium1]

Thanks for tracing this Windows checkpoint failure to browser profile files.

Problems

• tools/checkpoint_manager.py:438-439 returns for every existing shared checkpoint store before the only info/exclude write at tools/checkpoint_manager.py:482-484. The added defaults therefore affect new stores only, while affected existing installations retain the old exclude file.
• Existing project checkpoints load their prior tree into a persistent index at tools/checkpoint_manager.py:1029-1034 before the git add -A at tools/checkpoint_manager.py:1048-1051. Ignore rules do not remove paths that were already tracked, so prior browser-profile snapshots need migration/cleanup too.

Suggested changes

• Refresh the managed exclude file for existing stores and remove matching already-tracked profile paths before staging; add behavioral tests for both an existing store/index and the two patterns.
• Please preserve LF line endings: the PR currently appears as +1678/-1675 for a three-line logical edit, which makes salvage unnecessarily risky.

Automated hermes-sweeper review.

[teknium1]

These defaults are only written for a newly initialized store: _init_store() returns at current main tools/checkpoint_manager.py:438-439 when store/HEAD exists, before the info/exclude write at lines 482-484. Please add an idempotent existing-store update path, otherwise the Windows installations already experiencing this issue retain the old exclude file.