feat(review): simplification specialist — advisory over-engineering lens with ponytail's tag vocabulary

New 8th Review Army specialist (DIFF_LINES > 100, --simplification force flag)
hunting unrequested STRUCTURE only: delete/stdlib/native/speculative/shrink
closed tags, one-line findings, lines_removable field. speculative: replaces
ponytail's yagni: tag — we import the lens, not the posture; coverage stays
sacred (Completeness Gaps owns it, suppressions inlined, shrink needs >=5 lines).

Advisory carve-out in the merge step: advisory findings are excluded from
quality_score and the findings-count header, render with an [ADVISORY] label,
and are ASK-only in Fix-First. Zero-findings case prints the lens-scoped
'Simplification: lean already — nothing to cut.' from the PARENT (the
specialist keeps the exact NO FINDINGS contract); with findings, the parent
prints 'net: -N lines possible' summed from lines_removable.

Tests: static pins for the carve-out + early-out contract (gen-skill-docs),
two periodic e2e cases with planted fixtures — activation (over-build traps:
hand-rolled Intl, one-impl abstract, dead config) and false-flag precision
(a lean ETHOS 'choose A' diff must yield NO FINDINGS).

Inspired by dietrichgebert/ponytail's /ponytail-review.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ship/sections/review-army.md

@@ -183,6 +183,7 @@ Based on the scope signals above, select which specialists to dispatch.
 5. **Data Migration** — if SCOPE_MIGRATIONS=true. Read `~/.claude/skills/gstack/review/specialists/data-migration.md`
 6. **API Contract** — if SCOPE_API=true. Read `~/.claude/skills/gstack/review/specialists/api-contract.md`
 7. **Design** — if SCOPE_FRONTEND=true. Use the existing design review checklist at `~/.claude/skills/gstack/review/design-checklist.md`
+8. **Simplification** — if DIFF_LINES > 100. Read `~/.claude/skills/gstack/review/specialists/simplification.md`. Advisory-only lens: hunts unrequested structure (hand-rolled stdlib, one-implementation abstractions, dependencies duplicating platform features), never coverage.
 
 ### Adaptive gating
 
@@ -192,7 +193,7 @@ For each conditional specialist that passed scope gating, check the `gstack-spec
 - If tagged `[GATE_CANDIDATE]` (0 findings in 10+ dispatches): skip it. Print: "[specialist] auto-gated (0 findings in N reviews)."
 - If tagged `[NEVER_GATE]`: always dispatch regardless of hit rate. Security and data-migration are insurance policy specialists — they should run even when silent.
 
-**Force flags:** If the user's prompt includes `--security`, `--performance`, `--testing`, `--maintainability`, `--data-migration`, `--api-contract`, `--design`, or `--all-specialists`, force-include that specialist regardless of gating.
+**Force flags:** If the user's prompt includes `--security`, `--performance`, `--testing`, `--maintainability`, `--data-migration`, `--api-contract`, `--design`, `--simplification`, or `--all-specialists`, force-include that specialist regardless of gating.
 
 Note which specialists were selected, gated, and skipped. Print the selection:
 "Dispatching N specialists: [names]. Skipped: [names] (scope not detected). Gated: [names] (0 findings in N+ reviews)."
@@ -277,8 +278,14 @@ Group findings by fingerprint. For findings sharing the same fingerprint:
 - Confidence 3-4: move to appendix (suppress from main findings)
 - Confidence 1-2: suppress entirely
 
+**Advisory carve-out (simplification specialist):**
+Findings with `"advisory": true` are excluded from BOTH the quality_score
+summation and the findings-count header below — they are structure suggestions,
+not defects, and must not make "5 findings … 10/10" look contradictory. In
+Fix-First they are ASK-only: NEVER auto-applied, even when mechanical.
+
 **Compute PR Quality Score:**
-After merging, compute the quality score:
+After merging, compute the quality score over NON-advisory findings only:
 `quality_score = max(0, 10 - (critical_count * 2 + informational_count * 0.5))`
 Cap at 10. Log this in the review result at the end.
 
@@ -288,7 +295,8 @@ Present the merged findings in the same format as the current review:
 ```
 SPECIALIST REVIEW: N findings (X critical, Y informational) from Z specialists
 
-[For each finding, in order: CRITICAL first, then INFORMATIONAL, sorted by confidence descending]
+[For each finding, in order: CRITICAL first, then INFORMATIONAL, sorted by confidence descending;
+ advisory findings last, each rendered with an [ADVISORY] label in place of the severity]
 [SEVERITY] (confidence: N/10, specialist: name) path:line — summary
   Fix: recommended fix
   [If MULTI-SPECIALIST CONFIRMED: show confirmation note]
@@ -296,12 +304,20 @@ SPECIALIST REVIEW: N findings (X critical, Y informational) from Z specialists
 PR Quality Score: X/10
 ```
 
+**Simplification footer (after the score line):**
+- If the simplification specialist was dispatched and returned findings, sum
+  their `lines_removable` values and print: `net: -N lines possible` (omit
+  findings without the field from the sum).
+- If it was dispatched and returned NO FINDINGS, print:
+  `Simplification: lean already — nothing to cut.`
+- If it was not dispatched, print neither line.
+
 These findings flow into the Fix-First flow (item 4) alongside the checklist pass (Step 9).
-The Fix-First heuristic applies identically — specialist findings follow the same AUTO-FIX vs ASK classification.
+The Fix-First heuristic applies identically — specialist findings follow the same AUTO-FIX vs ASK classification (except advisory findings, which are ASK-only per the carve-out above).
 
 **Compile per-specialist stats:**
 After merging findings, compile a `specialists` object for the review-log persist.
-For each specialist (testing, maintainability, security, performance, data-migration, api-contract, design, red-team):
+For each specialist (testing, maintainability, security, performance, data-migration, api-contract, design, simplification, red-team):
 - If dispatched: `{"dispatched": true, "findings": N, "critical": N, "informational": N}`
 - If skipped by scope: `{"dispatched": false, "reason": "scope"}`
 - If skipped by gating: `{"dispatched": false, "reason": "gated"}`