## Why
The transcript supplied to Guardian may omit earlier user instructions, restrictions, or revoked permissions. History retrieval lets the reviewer check relevant authorization before approving actions with side effects.
## What changed
- Add the disabled-by-default `guardian_conversation_history_tools` feature. With Apps enabled, expose `user_message.search_messages` and `user_message.read_messages` through the parent's live Apps connection and conversation identity.
- Recheck the parent's current app and tool policy on each call, rejecting disabled tools and calls requiring approval.
- Add retrieval instructions that distinguish user authorization from assistant context and account for later revocations and incomplete results. Allow overrides through `auto_review.experimental_conversation_history_prompt`.
- Limit history responses to an estimated 4,000 tokens by default, configurable through `auto_review.conversation_history_max_output_tokens`, while preserving stricter parent and reviewer limits.
- Allow explicit extension registries for isolated sessions and prevent those sessions from inheriting the implicit Apps connection.
## Testing
Add scenarios covering history tool exposure, parent connection and identity reuse, custom prompts, output truncation, stricter reviewer budgets, and live permission changes on a reused reviewer. Extend configuration coverage for blank prompt overrides.
GitOrigin-RevId: 055a69b113c8548bd58e7d5618ea026ba6d1ffb1
## Why
Session isolation relied on Guardian source attribution. An explicit policy lets callers control inherited capabilities independently of how a session is attributed.
## What changed
- Add `SessionIsolation` with default `Inherit` and opt-in `Isolated` modes, captured at session startup through `ExtensionDataInit`.
- Use the policy to control inherited instructions, extensions, execution rules, and MCP resources. Isolated sessions retain managed execution rules and omit executor-discovered MCP servers.
- Explicitly isolate Guardian reviewers while preserving source-based fallback for older callers and saved reviewers.
## Testing
Extend delegate tests to cover isolation independently of attribution, update execution-policy coverage to supply the explicit policy, and assert that managed reviewers do not inherit the parent's configured MCP tools.
GitOrigin-RevId: f0ab42fa2f0237860ec661e72693ab191216afbf
felixxia-oai