# Decisions

## Evidence Reference

Use `source_invocation_id + raw_path + evidence_excerpt` as the precise evidence reference for Executor claim bindings.

Reason:

- Invocation ID alone only identifies a tool call, not the evidence inside it.
- `raw_path` is enough for the first version when paired with `retrieval_details.evidence_refs`.
- `evidence_excerpt` remains the text Verifier reads, but only after Gatekeeper validates it.

## Raw Path

Only support stable locators in the first version:

- `$.alerts[i]`
- `$.logs[i]`
- `$.evidence_blocks[i]`

No full JSONPath engine is introduced.

## Gatekeeper Severity

Gatekeeper output includes:

- `status`
- `severity`
- `checked_bindings`
- `failed_rules`
- `warnings`
- `errors`

Severity meaning:

- `none`: precise references passed.
- `low_confid`: evidence is missing or incomplete, but not fabricated.
- `reject`: fabricated ID, wrong tool, unknown raw path, or mismatched excerpt.

## Verifier Boundary

Verifier uses verified claim-local excerpts as primary derivability evidence. `tool_trace_summary` remains available for navigation and audit, but no longer needs to carry every concrete fact.

## Hook Placement

Gatekeeper remains in the Verifier input hook path. This version does not retry Executor on Gatekeeper failure.

## Planner

Planner is not changed. `scope_contract` remains a later-stage idea. This phase uses prompt constraints to reduce narrow-scope over-expansion.

## Database

No new tables. Evidence refs are stored in `tool_invocation.retrieval_details.evidence_refs`; audit is stored in `diagnosis_session.self_evaluation.verifier_evaluation.gatekeeper_result`.