## Why
Guardian V2 needs the requested action and its conversation context to assess
risk; a tool name and call ID alone do not describe what the tool will do.
## What changed
- Expose the original, pre-hook `ToolPayload` to tool lifecycle contributors.
- Build Guardian V2 classifier input from the bounded conversation transcript
and a structured planned-action object containing the tool name and arguments.
- Warn and skip classification if the planned action cannot be serialized.
## Testing
- Verify lifecycle contributors receive tool arguments.
- Verify Guardian V2 sends transcript history and planned-action JSON to the
classifier.
GitOrigin-RevId: 28266ef7c1d2267ba705fcfbd9be4ef48e64e104
## What changed
- Add a shared, read-only `ConversationHistorySnapshot` capability to the extension API.
- Include the snapshot in `ToolStartInput`, preserving conversation order while excluding contextual user messages.
- Avoid acquiring a history snapshot when no tool lifecycle contributors are registered.
## Testing
- Verify snapshots share existing response items, remain stable as history changes, and filter contextual user messages.
- Verify tool-start callbacks receive the history available for successive tool calls.
GitOrigin-RevId: 822cae33781dd876ea628f104be08d8a449a4900
felixxia-oai