What does this PR do?

Mounts ~/.hermes/images into remote sandboxes in addition to the existing cache directories. Clipboard screenshots are saved under ~/.hermes/images, but remote backends only mirrored cache directories like image_cache, which left pasted screenshots invisible inside Docker/remote sandboxes. This PR adds the missing mount + per-file sync coverage so pasted clipboard images become visible to sandboxed runs.

Related Issue

Closes #6004

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

• Add ("images", "images") to _CACHE_DIRS in tools/credential_files.py
• Add tests verifying:
  • sandbox mount entry for /root/.hermes/images
  • per-file iteration includes files from ~/.hermes/images

How to Test

1. Activate the repo venv
2. Run:

   /workspace/Projects/hermes-agent/.venv/bin/python -m pytest -n 0 \
     tests/tools/test_credential_files.py \
     tests/tools/test_clipboard.py -q

3. Confirm all tests pass (observed locally: 126 passed in 7.58s)

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: macOS 15 (Darwin 24.6.0)

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

Screenshots / Logs

/workspace/Projects/hermes-agent/.venv/bin/python -m pytest -n 0 \
  tests/tools/test_credential_files.py \
  tests/tools/test_clipboard.py -q
# 126 passed in 7.58s