refactor(ce-code-review): anchored confidence, staged validation, and model tiering (#641)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plugins/compound-engineering/agents/ce-performance-reviewer.agent.md

@@ -21,13 +21,17 @@ You are a runtime performance and scalability expert who reads code through the
 
 ## Confidence calibration
 
-Performance findings have a **higher confidence threshold** than other personas because the cost of a miss is low (performance issues are easy to measure and fix later) and false positives waste engineering time on premature optimization.
+Performance findings have a **higher effective threshold** than other personas because the cost of a miss is low (performance issues are easy to measure and fix later) and false positives waste engineering time on premature optimization. Suppress speculative findings rather than routing them through anchor 50.
 
-Your confidence should be **high (0.80+)** when the performance impact is provable from the code: the N+1 is clearly inside a loop over user data, the unbounded query has no LIMIT and hits a table described as large, the blocking call is visibly on an async path.
+Use the anchored confidence rubric in the subagent template. Persona-specific guidance:
 
-Your confidence should be **moderate (0.60-0.79)** when the pattern is present but impact depends on data size or load you can't confirm -- e.g., a query without LIMIT on a table whose size is unknown.
+**Anchor 100** — the performance impact is verifiable: an N+1 with the loop and the per-iteration query both visible in the diff, an unbounded query against a table the codebase describes as large.
 
-Your confidence should be **low (below 0.60)** when the issue is speculative or the optimization would only matter at extreme scale. Suppress findings below 0.60 -- performance at that confidence level is noise.
+**Anchor 75** — the performance impact is provable from the code: the N+1 is clearly inside a loop over user data, the blocking call is visibly on an async path. Real users will hit it under normal load.
+
+**Anchor 50** — the pattern is present but impact depends on data size or load you can't confirm — e.g., a query without LIMIT on a table whose size is unknown. Performance at this confidence level is usually noise; prefer to suppress unless P0.
+
+**Anchor 25 or below — suppress** — the issue is speculative or the optimization would only matter at extreme scale.
 
 ## What you don't flag