docs(specs): SDD fix-loop redesign design spec

Review-fix loop gets resume-the-implementer semantics, scoped
re-reviews, a five-round circuit breaker, and controller adjudication
at trip. SKILL.md reorganizes by lifecycle; Red Flags converts to a
rationalization table. Brainstormed with Jesse 2026-07-15.

Author: obra

docs/superpowers/specs/2026-07-15-sdd-fix-loop-redesign-design.md

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+# SDD Fix-Loop Redesign — Design Spec
+
+**Status:** Approved design (brainstormed with Jesse 2026-07-15); implementation
+plan to follow.
+**Objective:** make the subagent-driven-development skill's review-fix loop
+convergent and autonomous, and make the document readable, without rewriting
+its eval-tuned language.
+**Hard invariant:** existing eval-tuned sentences move; they do not get
+reworded. New machinery ships with drill evidence.
+
+## Problems
+
+Four, all observed in real sessions:
+
+1. **Pathological review loops.** The loop is literally "Repeat until
+   approved" — no round cap. Each re-review is a fresh full review of the
+   whole diff, so a nondeterministic frontier reviewer surfaces new findings
+   every round instead of verifying fixes. Result: implement, review, fix,
+   review, review, fix, review, fix — with no circuit breaker. The
+   strict-cost spec (2026-06-10) independently measured review-loop count as
+   the biggest run-to-run cost variance.
+2. **Contradictory fix policy.** The process diagram and "Constructing
+   Reviewer Prompts" dispatch dedicated fix subagents; Red Flags says
+   "Implementer (same subagent) fixes them"; implementer-prompt.md's "After
+   Review Findings" section assumes the implementer will be re-engaged. Three
+   answers to "who fixes?" in one skill.
+3. **Accreted structure.** Thirteen top-level sections; guidance for one
+   activity is scattered across four of them. "Constructing Reviewer Prompts"
+   is a grab-bag holding reviewer guidance, fix policy, final-review policy,
+   and plan-conflict adjudication.
+4. **Red Flags format.** Seven sibling skills use the `| Excuse | Reality |`
+   rationalization table; SDD carries a 17-bullet "Never" list plus three
+   "If X" mini-blocks.
+
+## Design Decisions
+
+| # | Decision | Rationale |
+|---|----------|-----------|
+| 1 | The original implementer fixes its own review findings — resume it in place. | It already holds the task context; ownership beats a drive-by patcher. Fresh "fix subagents" rebuild context per finding and lack the task frame. |
+| 2 | Re-reviews are scoped to the findings. | Fresh full reviews each round are the churn engine. Scoped re-reviews make the loop structurally convergent; the final whole-branch review remains the broad safety net. |
+| 3 | Circuit breaker at five fix rounds: three resumes, then two fresh dispatches on a more capable model. | Jesse's call. A loop that survives three resumes usually means the implementer cannot see its own problem — the fresh capable dispatch de-anchors and capability-bumps in one move. |
+| 4 | At trip, the controller adjudicates and routes. No new human checkpoint — structural failures reach the existing BLOCKED stop. | SDD's point is autonomous execution. The controller holds the plan and cross-task context the reviewer lacks; the existing text already sanctions it ("adjudicate it in the review loop") without ever specifying the mechanism. |
+| 5 | Reorganize SKILL.md by lifecycle, preserving tuned sentences. | Fixes "hard to follow" at the root. Content moves to its point of use, matching the house direction (recent commits fold recap sections into points of use). |
+| 6 | Convert Red Flags to a `| Excuse | Reality |` rationalization table; relocate hard rules to their points of use. | Matches the other seven skills. Excuses get rebuttals; rules get enforced where the reader acts. |
+
+## The Fix Loop
+
+Trigger: a task review returns spec ❌ or any Critical/Important finding.
+
+**Rounds 1–3 — resume the original implementer.** Send the findings verbatim
+(Critical/Important plus spec gaps). The implementer fixes, re-runs the
+covering tests, appends the fix report to its existing report file, and
+returns the short contract. On a harness without agent resume, a "resume" is
+a fresh dispatch carrying the brief, the report file, and the findings — the
+report file is the persistent memory either way.
+
+**Rounds 4–5 — fresh implementer, more capable model.** Full task context:
+brief, report file, open findings, and the framing "a prior implementer
+attempted this N times; you own the task now."
+
+**Every round's re-review is scoped.** The re-reviewer receives the brief,
+the updated report, the original findings list, and a fix-scoped diff package
+(`review-package FIX_BASE HEAD`, where FIX_BASE is the head the reviewer
+last reviewed; the script already takes arbitrary ranges).
+It verdicts each finding addressed / not addressed and flags new breakage in
+the fix diff only. Novel findings on code the fix did not touch are reported
+as non-blocking; the controller ledgers them for the final review.
+
+**Fix-report completeness gate (existing rule, kept):** before dispatching a
+re-review, confirm the fix report names the covering tests, the command run,
+and the output.
+
+**No early exit.** The controller never adjudicates before the cap — an early
+exit reopens the "pre-judge findings to spare yourself a review loop" hole
+the current content deliberately closed. One exception, unchanged from
+today: a finding that conflicts with what the plan's text mandates goes to
+the human immediately (plan authority, not loop churn).
+
+**Minor findings** never enter the loop: ledger them as they arrive (existing
+rule, kept).
+
+### Adjudication at Trip
+
+After round five fails, the controller stops dispatching and judges each open
+finding against the brief, the plan, and cross-task context:
+
+- **Contested or wrong** → ledger with a one-line adjudication ("controller:
+  reviewer wrong because X"), continue. The final review sees both sides.
+- **Real, not load-bearing** → ledger as known-open, continue. Later
+  dispatches touching that area carry a pointer to the entry.
+- **Real and load-bearing** (later tasks build on it, or it reveals a plan
+  defect) → the existing BLOCKED stop. Park-and-continue defers a structural
+  failure to the most expensive point and lets dependents build on it, so
+  structural failures stop the run — through the stop condition that already
+  exists, not a new checkpoint.
+
+Every adjudication is a ledger entry. Silent discards stay forbidden.
+
+## Document Restructure
+
+New skeleton, in execution order:
+
+1. Intro — why subagents, core principle, narration, continuous execution
+2. When to Use — unchanged, including the decision graph
+3. The Process — diagram updated for the new loop
+4. Setup — worktree, ledger check/resume, pre-flight plan review, todos
+5. Model Selection — stays one cross-cutting section; every dispatch
+   consults it, so folding it into points of use would repeat it five times
+6. The Task Loop — five numbered steps:
+   1. Dispatch the implementer (task-brief script, five-part dispatch
+      composition, model line required)
+   2. Handle the report (DONE / DONE_WITH_CONCERNS / NEEDS_CONTEXT / BLOCKED)
+   3. Review the task (review-package script, reviewer dispatch composition,
+      constraints lens, no pre-judging, ⚠️ handling)
+   4. Fix loop (the machinery above)
+   5. Complete the task (ledger append, todo update)
+7. Final Review — package, model pin, one fix wave, one scoped re-review,
+   adjudication
+8. Finish — finishing-a-development-branch
+9. Common Rationalizations — the table
+10. Example Workflow — updated to show a resume-based fix round and the
+    breaker not tripping
+
+"Constructing Reviewer Prompts," "File Handoffs," and "Durable Progress"
+dissolve into the steps where each rule applies. Every eval-tuned sentence
+lands in exactly one new location; a move map in the implementation plan
+tracks source → destination so review can verify nothing was dropped or
+reworded.
+
+## Rationalization Table
+
+Excuse-shaped Never items convert to rows; new rows cover the loop
+pathology. Draft rows (final wording at implementation):
+
+| Excuse | Reality |
+|--------|---------|
+| "Close enough on spec compliance" | Reviewer found gaps = not done. |
+| "I'll fix it myself, dispatching is overhead" | Controller fixes pollute your context and skip review. Resume the implementer. |
+| "One more round will converge" | Past the cap, rounds don't converge. Adjudicate. |
+| "The reviewer will just find something new anyway" | Scoped re-reviews check fixes, not taste. New findings on untouched code go to the ledger, not the loop. |
+| "This finding is obviously wrong, I'll drop it" | You adjudicate only at the cap, and every adjudication is a ledger entry. Silent discards are forbidden. |
+| "The fix was small, skip the re-review" | Unreviewed fixes are how regressions land. |
+
+Hard rules that are not excuses (never parallel implementers, never dispatch
+a reviewer without a diff file, model line required, never re-dispatch
+ledger-complete tasks) move to their points of use.
+
+## Prompt Templates
+
+- **implementer-prompt.md** — "After Review Findings" rewritten for resume
+  semantics: you will be resumed with findings; fix, re-run covering tests,
+  append to your report file, return the short contract.
+- **task-reviewer-prompt.md** — initial review only; the trailing re-review
+  sentence moves out.
+- **re-review-prompt.md (new)** — the scoped re-review contract: inputs are
+  brief, updated report, original findings, fix-scoped diff package; output
+  is a per-finding verdict (addressed / not addressed), new breakage in the
+  fix diff, and non-blocking observations outside it. A separate template
+  because it is a different contract — overloading the full-review template
+  produced the current ambiguity.
+- **Takeover dispatch (rounds 4–5)** — composed from implementer-prompt.md
+  plus SKILL.md guidance (brief, report path, open findings, takeover
+  framing); no new template file.
+
+## Final Review Loop
+
+Unchanged: merge-base package, most capable model, ONE fixer with the
+complete findings list. New: exactly one scoped re-review of the fix wave,
+then controller adjudication. Residual load-bearing findings surface at
+finishing-a-development-branch, where the human already is. The end of the
+branch gets a bounded loop too.
+
+## Evals
+
+Three new drill scenarios in `evals/`:
+
+1. **Resume, don't re-dispatch:** a task review returns findings; the
+   controller must resume the same implementer rather than dispatch a fix
+   subagent.
+2. **Breaker trips:** a seeded never-satisfied reviewer; the controller must
+   stop dispatching after the fifth round fails, adjudicate, ledger, and
+   continue — not loop.
+3. **Structural finding stops:** a load-bearing finding (later tasks depend
+   on it); the controller must stop via BLOCKED rather than park.
+
+Plus before/after runs of the existing SDD scenarios to catch regressions
+from the reorganization.
+
+## Non-Goals
+
+- Ledger session-scoping — PR #1943 owns it. This work touches the same
+  sections, so the implementation plan notes the collision risk.
+- Script changes — task-brief and review-package already do what the new
+  loop needs.
+- Changes to executing-plans or requesting-code-review beyond the final-
+  review pointer continuing to resolve.