I've completed all phases. Here's my analysis before the summary:

**Phase 1–3 (drift):** fn-81.2 changed review-backend **plumbing** (file composition, single-entry responses, fix-loop cap, snapshot-scoped staging, unique temp paths) in `flow-next-plan-review`, `flow-next-impl-review`, `flow-next-spec-completion-review`, and `flow-next-export-context`. The done summary is detailed and self-consistent with the spec's R8/R9/R10/R11/R13. No new names/APIs/paths were invented that diverge from the spec's `path-persistence` template.

**Phase 4 (downstream):**
- **fn-81.3** (R3/R4/R5/R6/R7/R12/R13) touches an entirely disjoint file set — `flow-next-plan` (≠ `plan-review`), `deps`, `make-pr`, `tracker-sync`, `work`, `resolve-pr`, `prime`. It depends on fn-81.1's conventions, not fn-81.2's, and contains **no reference** to fn-81.2's review-skill outputs. Nothing stale.
- **fn-81.4** (R13/R14/R15) is the validation gate; its cross-task greps (`[PASTE` empty; `git add -A` empty in impl-review/spec-completion-review; absent fixed paths `/tmp/review-prompt.md`, `/tmp/re-review.md`, `/tmp/updated-plan.md`, `/tmp/export-prompt.md`, `/tmp/completion-review-prompt.md`) **exactly match** what fn-81.2's done summary reports it produced. No stale expectations.

**Phase 3b:** Not a husk (glossary 38 terms, 2 decisions, populated strategy), so I checked each signal — but none flag against this task: **3b.1** every glossary entry has `avoid: []` → no aliases to detect. **3b.2** both decisions name files (`platforms.md`/capture/make-pr/setup/interview/plan/hooks.json; tracker-sync/make-pr/land) that fn-81.2 never touched → no override. **3b.3** fn-81.2 is pure in-repo skill plumbing that *serves* the Ralph/Self-improving/Cross-parity tracks — no SaaS/dep/hosted contradiction, no track-rename.

**Phase 5 traceability:** parent spec's `## Requirement coverage` table already lists fn-81.2 for R8/R9/R10/R11/R13, matching delivered scope. No row change.

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Drift detected: no

- fn-81.2 implemented per spec: RP file composition (zero `[PASTE` content-re-typing placeholders; surviving brackets scalar-only), single-entry responses in all three RP handlers, backend-agnostic fix-loop cap (`MAX_REVIEW_ITERATIONS`, default 3), snapshot-scoped staging replacing `git add -A`, and unique temp paths. No naming/API/path divergence from the spec.

Downstream tasks checked — no stale references, no updates warranted:
- fn-81.3: disjoint file set (`plan`/`deps`/`make-pr`/`tracker-sync`/`work`/`resolve-pr`/`prime`); anchors on fn-81.1 conventions, not fn-81.2. Clean.
- fn-81.4: validation-gate greps align exactly with fn-81.2's actual output (no `[PASTE`, no `git add -A` in the two RP review skills, old fixed temp paths absent). Clean.

Would update traceability: none — `## Requirement coverage` already maps R8/R9/R10/R11/R13 to fn-81.2 correctly.

Decision overrides flagged for review: none — neither active decision names a file fn-81.2 modified.

Strategy drift flagged for review: none — plumbing changes align with the Ralph autonomous mode, Cross-platform parity, and Self-improving tracks; no SaaS/dependency/hosted-endpoint contradiction.

No files modified (DRY_RUN).