feat(skills): add edge case hunter as parallel review layer in PR review

Wire review-edge-case-hunter.xml into bmad-os-review-pr as a second
review layer running in parallel with the adversarial review. Both
subagents receive the same PR diff concurrently. Findings are merged,
deduplicated, and tagged by source before tone transformation.

.claude/skills/bmad-os-review-pr/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: bmad-os-review-pr
-description: Adversarial PR review tool (Raven's Verdict). Cynical deep review transformed into professional engineering findings. Use when user asks to 'review a PR' and provides a PR url or id.
+description: Dual-layer PR review tool (Raven's Verdict). Runs adversarial cynical review and edge case hunter in parallel, merges and deduplicates findings into professional engineering output. Use when user asks to 'review a PR' and provides a PR url or id.
 ---
 
 Read `prompts/instructions.md` and execute.

.claude/skills/bmad-os-review-pr/prompts/instructions.md

@@ -93,13 +93,17 @@ gh pr diff {PR_NUMBER} [--repo {REPO}] --name-only | grep -E '\.(png|jpg|jpeg|gi
 
 Store list of binary files to skip. Note them in final output.
 
-## Adversarial Review
+## Review Layers
 
-### 1.1 Run Cynical Review
+**Launch steps 1.1 and 1.2 as parallel subagents** using the Task tool. Both receive the same PR diff and run concurrently. Wait for both to complete before proceeding to step 1.3.
+
+### 1.1 Run Cynical Review (subagent)
+
+Spawn a subagent with the following prompt. Pass the full PR diff as context.
 
 **INTERNAL PERSONA - Never post this directly:**
 
-Task: You are a cynical, jaded code reviewer with zero patience for sloppy work. This PR was submitted by a clueless weasel and you expect to find problems. Find at least five issues to fix or improve in it. Number them. Be skeptical of everything. Ultrathink.
+Task: You are a cynical, jaded code reviewer with zero patience for sloppy work. This PR was submitted by a clueless weasel and you expect to find problems. Find at least five issues to fix or improve in it. Number them. Be skeptical of everything.
 
 Output format:
 
@@ -124,14 +128,64 @@ Likely tag:
 - Add `[likely]` to findings with high confidence, e.g. with direct evidence
 - Sort findings by severity (Critical → Moderate → Minor), not by confidence
 
+### 1.2 Run Edge Case Hunter (subagent)
+
+Spawn a subagent that executes the task defined in `_bmad/core/tasks/review-edge-case-hunter.xml`. Pass the full PR diff as the `content` input. Omit `also_consider` unless the user specified extra focus areas.
+
+The task returns a JSON array of objects, each with: `location`, `trigger_condition`, `guard_snippet`, `potential_consequence`.
+
+**Map each JSON finding to the standard finding format:**
+
+```markdown
+### [NUMBER]. [trigger_condition] [likely]
+
+**Severity:** [INFERRED_EMOJI] [INFERRED_LEVEL]
+
+**`[location]`** — [trigger_condition]. [potential_consequence].
+
+**Suggested fix:**
+```
+[guard_snippet]
+```
+```
+
+Severity inference rules for edge case findings:
+
+- **Critical** — data loss, security, or crash conditions (null deref, unhandled throw, auth bypass)
+- **Moderate** — logic errors, silent wrong results, race conditions
+- **Minor** — cosmetic edge cases, unlikely boundary conditions
+
+Add `[likely]` to all edge case findings — they are derived from mechanical path tracing, so confidence is inherently high.
+
+If the edge case hunter returns zero findings or halts, note it internally and proceed — step 1.1 findings still stand.
+
+### 1.3 Merge and Deduplicate
+
+Combine the findings from step 1.1 (adversarial) and step 1.2 (edge case hunter) into a single list.
+
+**Deduplication rules:**
+
+1. Compare each edge case finding against each adversarial finding
+2. Two findings are duplicates if they reference the same file location AND describe the same gap (use description similarity — same function/variable/condition mentioned)
+3. When a duplicate is found, keep the version with more specificity (usually the edge case hunter's, since it includes `guard_snippet`)
+4. Mark the kept finding with the source that produced it
+
+**After dedup, renumber all findings sequentially and sort by severity (Critical → Moderate → Minor).**
+
+Tag each finding with its source:
+
+- `[Adversarial]` — from step 1.1 only
+- `[Edge Case]` — from step 1.2 only
+- `[Both]` — flagged by both layers (deduped)
+
 ## Tone Transformation
 
-**Transform the cynical output into cold engineering professionalism.**
+**Transform the merged findings into cold engineering professionalism.**
 
 **Transformation rules:**
 
 1. Remove all inflammatory language, insults, assumptions about the author
-2. Keep all technical substance, file references, severity ratings and likely tag
+2. Keep all technical substance, file references, severity ratings, likely tag, and **source tags**
 3. Replace accusatory phrasing with neutral observations:
    - ❌ "The author clearly didn't think about..."
    - ✅ "This implementation may not account for..."
@@ -140,6 +194,7 @@ Likely tag:
    - ✅ "This pattern has historically caused issues in production environments"
 5. Add the suggested fixes.
 6. Keep suggestions actionable and specific
+7. Edge case hunter findings need no persona cleanup, but still apply professional formatting consistently
 
 Output format after transformation:
 
@@ -149,18 +204,20 @@ Output format after transformation:
 **Title:** {PR_TITLE}
 **Author:** @{AUTHOR}
 **Branch:** {HEAD} → {BASE}
+**Review layers:** Adversarial + Edge Case Hunter
 
 ---
 
 ### Findings
 
-[TRANSFORMED FINDINGS HERE]
+[TRANSFORMED FINDINGS HERE — each tagged with source]
 
 ---
 
 ### Summary
 
 **Critical:** {COUNT} | **Moderate:** {COUNT} | **Minor:** {COUNT}
+**Sources:** {ADVERSARIAL_COUNT} adversarial | {EDGE_CASE_COUNT} edge case | {BOTH_COUNT} both
 
 [BINARY_FILES_NOTE if any]