Expand description
Session-start environment snapshot (C1 in CC’s taxonomy).
Captures git branch / HEAD / working-tree status once at session
start (or on ChangeDir), memoized by ownership: the struct lives on
AgentLoop, is constructed in new(), and renders into
build_system_prompt as a dedicated section.
§Why snapshot, not live
Git status changes every turn (every tool call shifts working tree state). If we re-read each turn, the system-prompt prefix changes every turn → prompt cache breaks → every turn re-bills full prefix. CC observed this tradeoff and chose snapshot-at-session-start with an explicit disclaimer in prompt text, so the model doesn’t mistake stale info for live state. We follow that pattern.
§Graceful degradation
Non-git directories, no git binary on PATH, detached HEAD, permission
errors — all surface as git: None and the prompt section is simply
omitted. No panics, no half-rendered sections.
Structs§
- EnvSnapshot
- Session-start environment snapshot.
- GitSnapshot
- Git repository state at the moment of capture.