Replace subagent review loops with lightweight inline self-review

The subagent review loop (dispatching a fresh agent to review plans/specs)
doubled execution time (~25 min overhead) without measurably improving plan
quality. Regression testing across 5 versions (v3.6.0 through v5.0.4) with
5 trials each showed identical plan sizes, task counts, and quality scores
regardless of whether the review loop ran.

Changes:
- writing-plans: Replace subagent Plan Review Loop with inline Self-Review
  checklist (spec coverage, placeholder scan, type consistency)
- writing-plans: Add explicit "No Placeholders" section listing plan failures
  (TBD, vague descriptions, undefined references, "similar to Task N")
- brainstorming: Replace subagent Spec Review Loop with inline Spec Self-Review
  (placeholder scan, internal consistency, scope check, ambiguity check)
- Both skills now use "look at it with fresh eyes" framing

Testing: 5 trials with the new skill show self-review catches 3-5 real bugs
per run (spawn positions, API mismatches, seed bugs, grid indexing) in ~30s
instead of ~25 min. Remaining defects are comparable to the subagent approach.

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

skills/brainstorming/SKILL.md

@@ -27,7 +27,7 @@ You MUST create a task for each of these items and complete them in order:
 4. **Propose 2-3 approaches** — with trade-offs and your recommendation
 5. **Present design** — in sections scaled to their complexity, get user approval after each section
 6. **Write design doc** — save to `docs/superpowers/specs/YYYY-MM-DD-<topic>-design.md` and commit
-7. **Spec review loop** — dispatch spec-document-reviewer subagent with precisely crafted review context (never your session history); fix issues and re-dispatch until approved (max 3 iterations, then surface to human)
+7. **Spec self-review** — quick inline check for placeholders, contradictions, ambiguity, scope (see below)
 8. **User reviews written spec** — ask user to review the spec file before proceeding
 9. **Transition to implementation** — invoke writing-plans skill to create implementation plan
 
@@ -43,8 +43,7 @@ digraph brainstorming {
     "Present design sections" [shape=box];
     "User approves design?" [shape=diamond];
     "Write design doc" [shape=box];
-    "Spec review loop" [shape=box];
-    "Spec review passed?" [shape=diamond];
+    "Spec self-review\n(fix inline)" [shape=box];
     "User reviews spec?" [shape=diamond];
     "Invoke writing-plans skill" [shape=doublecircle];
 
@@ -57,10 +56,8 @@ digraph brainstorming {
     "Present design sections" -> "User approves design?";
     "User approves design?" -> "Present design sections" [label="no, revise"];
     "User approves design?" -> "Write design doc" [label="yes"];
-    "Write design doc" -> "Spec review loop";
-    "Spec review loop" -> "Spec review passed?";
-    "Spec review passed?" -> "Spec review loop" [label="issues found,\nfix and re-dispatch"];
-    "Spec review passed?" -> "User reviews spec?" [label="approved"];
+    "Write design doc" -> "Spec self-review\n(fix inline)";
+    "Spec self-review\n(fix inline)" -> "User reviews spec?";
     "User reviews spec?" -> "Write design doc" [label="changes requested"];
     "User reviews spec?" -> "Invoke writing-plans skill" [label="approved"];
 }
@@ -116,12 +113,15 @@ digraph brainstorming {
 - Use elements-of-style:writing-clearly-and-concisely skill if available
 - Commit the design document to git
 
-**Spec Review Loop:**
-After writing the spec document:
+**Spec Self-Review:**
+After writing the spec document, look at it with fresh eyes:
 
-1. Dispatch spec-document-reviewer subagent (see spec-document-reviewer-prompt.md)
-2. If Issues Found: fix, re-dispatch, repeat until Approved
-3. If loop exceeds 3 iterations, surface to human for guidance
+1. **Placeholder scan:** Any "TBD", "TODO", incomplete sections, or vague requirements? Fix them.
+2. **Internal consistency:** Do any sections contradict each other? Does the architecture match the feature descriptions?
+3. **Scope check:** Is this focused enough for a single implementation plan, or does it need decomposition?
+4. **Ambiguity check:** Could any requirement be interpreted two different ways? If so, pick one and make it explicit.
+
+Fix any issues inline. No need to re-review — just fix and move on.
 
 **User Review Gate:**
 After the spec review loop passes, ask the user to review the written spec before proceeding: