[docs] docs: sync with selective mounting and security features

[github-actions]

Documentation Sync - February 5-12, 2026

This PR synchronizes documentation with code changes from the past 7 days, focusing on the selective mounting security feature and related architectural updates.

Changes Made

• docs/usage.md: Added missing --allow-full-filesystem-access CLI flag documentation with security warning
• README.md: Added link to docs/selective-mounting.md in the "Explore the docs" section
• AGENTS.md: Updated Container Architecture section to reflect selective mounting as the default behavior (line 220)
• docs/architecture.md: Added documentation for three security features:
  • Selective mounting and credential protection (default behavior)
  • One-shot token library (LD_PRELOAD) for environment variable protection
  • MCP logs directory protection via tmpfs

Code Changes Referenced

• PR feat: implement selective mounting to prevent credential exfiltration #681 (f1e2b4e): Selective mounting implementation - the --allow-full-filesystem-access flag was added but not documented in docs/usage.md
• PR feat: hide /tmp/gh-aw/mcp-logs/ from agent containers #706, fix: use tmpfs to hide /tmp/gh-aw/mcp-logs directory from containers #709, fix: use 0o777 permissions for mcp-logs and squid-logs directories #710 (8d65bc9): MCP logs directory hiding via tmpfs - architectural change not documented
• PR feat: add one-shot token LD_PRELOAD library for single-use token access #604, feat: add skip-unset mode to one-shot token library with value preview (enabled by default) #640: One-shot token library implementation - architectural change not documented
• PR [docs] docs: add missing CLI flags to reference documentation #695 (6a967cd): CLI flags were documented in docs-site but docs/usage.md was missing the selective mounting flag

Verification

• ✅ All documentation changes reflect actual code behavior
• ✅ Links to docs/selective-mounting.md are correct (document exists and is current)
• ✅ Security warnings properly highlight the implications of --allow-full-filesystem-access
• ✅ Changes are minimal and focused on bringing docs in sync with recent code

Impact

These documentation updates are critical for security awareness - users need to know that:

1. Selective mounting is now the default (protects credentials)
2. The --allow-full-filesystem-access flag disables this protection
3. The architecture includes multiple layers of credential protection

AI generated by Documentation Maintainer

[github-actions]

PRs: [docs] docs: sync with selective mounting and security features | Lpcox/port one shot token rust
Tests: GitHub MCP ✅, Safeinputs GH ✅, Playwright ✅, Tavily ❌, File write ✅, Bash cat ✅, Discussion comment ✅, Build ✅
Overall: FAIL

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