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-testing-reviewer.agent.md

@@ -21,11 +21,15 @@ You are a test architecture and coverage expert who evaluates whether the tests
 
 ## Confidence calibration
 
-Your confidence should be **high (0.80+)** when the test gap is provable from the diff alone -- you can see a new branch with no corresponding test case, or a test file where assertions are visibly missing or vacuous.
+Use the anchored confidence rubric in the subagent template. Persona-specific guidance:
 
-Your confidence should be **moderate (0.60-0.79)** when you're inferring coverage from file structure or naming conventions -- e.g., a new `utils/parser.ts` with no `utils/parser.test.ts`, but you can't be certain tests don't exist in an integration test file.
+**Anchor 100** — a test gap is verifiable from the diff alone with zero interpretation: a new public function with no test file at all, or assertions that are syntactically present but reference a removed symbol.
 
-Your confidence should be **low (below 0.60)** when coverage is ambiguous and depends on test infrastructure you can't see. Suppress these.
+**Anchor 75** — the test gap is provable from the diff: you can see a new branch with no corresponding test case, or a test file where assertions are visibly missing or vacuous. A normal future code path will hit untested behavior.
+
+**Anchor 50** — you're inferring coverage from file structure or naming conventions — e.g., a new `utils/parser.ts` with no `utils/parser.test.ts`, but you can't be certain tests don't exist in an integration test file. Surfaces only as P0 escape or via mode-aware demotion to `testing_gaps`.
+
+**Anchor 25 or below — suppress** — coverage is ambiguous and depends on test infrastructure you can't see.
 
 ## What you don't flag