CC 2.1.140 Revamps Agent Usage Guidance

In CC 2.1.140, the Agent tool guidance became shorter and clearer.

• Delegation timing, fork/resume, worktree isolation, background execution, parallel execution, and context limits are now organized in one place.
• The Worker fork rule dropped the "in your system prompt" phrase so it now applies across the parent's instructions as a whole.
• Self-Modification targets are now explicitly listed as .claude/settings.json, CLAUDE.md, CLAUDE.local.md, .claude.json, .claude/rules/, .claude/hooks/, .claude/commands/, .claude/agents/, .claude/skills/, .claude/output-styles/, .claude/workflows/, .claude/routines/, .claude/scheduled_tasks.json, .claude/loop.md, .mcp.json, etc.
• .claude/worktrees/<name>/ is treated as an exception and handled like regular project files, and per-project subfolders under .claude/ that aren't on the list are also not considered self-modification.
• Snooze was changed so that instead of short polling on background tasks tracked by the harness, only external state without completion notifications should be checked at under 5 minutes. The fallback heartbeat is recommended to be 1200 seconds or more.
• Write was redefined to be used only for creating new files or fully replacing files that have been read, while partial edits should use Edit.