feat(ce-review): improve signal-to-noise with confidence rubric, FP suppression, and intent verification (#434)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plugins/compound-engineering/skills/ce-review/references/subagent-template.md

@@ -22,8 +22,25 @@ Return ONLY valid JSON matching the findings schema below. No prose, no markdown
 
 {schema}
 
+Confidence rubric (0.0-1.0 scale):
+- 0.00-0.29: Not confident / likely false positive. Do not report.
+- 0.30-0.49: Somewhat confident. Do not report -- too speculative for actionable review.
+- 0.50-0.59: Moderately confident. Real but uncertain. Do not report unless P0 severity.
+- 0.60-0.69: Confident enough to flag. Include only when the issue is clearly actionable.
+- 0.70-0.84: Highly confident. Real and important. Report with full evidence.
+- 0.85-1.00: Certain. Verifiable from the code alone. Report.
+
+Suppress threshold: 0.60. Do not emit findings below 0.60 confidence (except P0 at 0.50+).
+
+False-positive categories to actively suppress:
+- Pre-existing issues unrelated to this diff (mark pre_existing: true for unchanged code the diff does not interact with; if the diff makes it newly relevant, it is secondary, not pre-existing)
+- Pedantic style nitpicks that a linter/formatter would catch
+- Code that looks wrong but is intentional (check comments, commit messages, PR description for intent)
+- Issues already handled elsewhere in the codebase (check callers, guards, middleware)
+- Suggestions that restate what the code already does in different words
+- Generic "consider adding" advice without a concrete failure mode
+
 Rules:
-- Suppress any finding below your stated confidence floor (see your Confidence calibration section).
 - Every finding MUST include at least one evidence item grounded in the actual code.
 - Set pre_existing to true ONLY for issues in unchanged code that are unrelated to this diff. If the diff makes the issue newly relevant, it is NOT pre-existing.
 - You are operationally read-only. You may use non-mutating inspection commands, including read-oriented `git` / `gh` commands, to gather evidence. Do not edit files, change branches, commit, push, create PRs, or otherwise mutate the checkout or repository state.
@@ -32,8 +49,13 @@ Rules:
 - Set `requires_verification` to true whenever the likely fix needs targeted tests, a focused re-review, or operational validation before it should be trusted.
 - suggested_fix is optional. Only include it when the fix is obvious and correct. A bad suggestion is worse than none.
 - If you find no issues, return an empty findings array. Still populate residual_risks and testing_gaps if applicable.
+- **Intent verification:** Compare the code changes against the stated intent (and PR title/body when available). If the code does something the intent does not describe, or fails to do something the intent promises, flag it as a finding. Mismatches between stated intent and actual code are high-value findings.
 </output-contract>
 
+<pr-context>
+{pr_metadata}
+</pr-context>
+
 <review-context>
 Intent: {intent_summary}
 
@@ -52,5 +74,6 @@ Diff:
 | `{diff_scope_rules}` | `references/diff-scope.md` content | Primary/secondary/pre-existing tier rules |
 | `{schema}` | `references/findings-schema.json` content | The JSON schema reviewers must conform to |
 | `{intent_summary}` | Stage 2 output | 2-3 line description of what the change is trying to accomplish |
+| `{pr_metadata}` | Stage 1 output | PR title, body, and URL when reviewing a PR. Empty string when reviewing a branch or standalone checkout |
 | `{file_list}` | Stage 1 output | List of changed files from the scope step |
 | `{diff}` | Stage 1 output | The actual diff content to review |