prove-fix

name	prove-fix
version	1.1.0
description	[Code Quality] Use when you need to prove fix correctness with code proof traces, confidence scoring, and stack-trace-style evidence chains.

[BLOCKING] Execute skill steps in declared order. NEVER skip, reorder, or merge steps without explicit user approval. [BLOCKING] Before each step or sub-skill call, update task tracking: set in_progress when step starts, set completed when step ends. [BLOCKING] Every completed/skipped step MUST include brief evidence or explicit skip reason. [BLOCKING] If Task tools are unavailable, create and maintain an equivalent step-by-step plan tracker with the same status transitions.

Quick Summary

Goal: Block shipping an unproven fix — build a code proof trace (like a debugger stack trace) for each fix change with confidence percentages, so every code change carries a file:line evidence chain and confidence score and a fix ships only when its correctness is proven (≥80%), not assumed.

Summary:

• Runs AFTER /fix (never before) as the non-negotiable verification gate between /fix and /code-simplifier; build a stack-trace-style proof chain (symptom → trigger path → root cause → fix mechanism → why-correct → edge cases → side effects) per change, every arrow carrying file:line.
• Score each change with the points rubric (root cause +25, fix mechanism +20, pattern precedent +15, framework +10, edge cases +5 each, side effects +10, no regressions +5) → ≥80% ship, 60-79% flag, <60% BLOCK; pattern precedent (1+ working example) and edge cases (error/null/concurrent) are required, not optional.
• Map every fix part to a primary/contributing/latent root cause from the hypothesis matrix and prove ALL feeder paths are closed; finish with cross-change checks (interaction, completeness, regression, dependency, performance incl. paging/index DB protocol) and a final verdict.
• After the verdict, resolve the active Goal Contract: map each proof trace to its success criterion, update the Goal Satisfaction matrix — a SHIP verdict does NOT close work while any required criterion remains FAIL.

Workflow:

1. Inventory — List every code change made by the fix (file:line, before/after)
2. Trace — For each change, build a proof chain tracing from symptom → root cause → fix
3. Score — Assign confidence percentage per change with evidence
4. Verify — Cross-check fix against edge cases and side effects
5. Verdict — Overall fix confidence and any remaining risks

Key Rules:

• Every claim MUST ATTENTION have file:line evidence — no exceptions
• Each change gets its OWN proof trace and confidence score
• If ANY change scores below 80%, flag it and recommend additional investigation
• Always run this proof-trace step after /fix — non-negotiable, never skip it

Frontend/UI Context (if applicable)

When this task involves frontend or UI changes,

• Component patterns: docs/project-reference/frontend-patterns-reference.md
• Styling/BEM guide: docs/project-reference/scss-styling-guide.md
• Design system tokens: docs/project-reference/design-system/README.md

Be skeptical. Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence percentages (Idea should be more than 80%).

Prove Fix

Post-fix verification skill building evidence-based proof chains for every code change. A code debugger's stack trace, but for proving WHY a fix is correct.

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When to Use

• After /fix in bugfix, hotfix, or any fix workflow
• After applying code changes that fix a reported bug
• Verify fix correctness before review/commit

When NOT to Use

• Before fix applied (use /debug-investigate instead)
• New feature verification (use /test instead)
• Code quality review (use /code-review instead)

---

Step 1: Change Inventory

List ALL changes made by the fix. For each change, document:

CHANGE #N: [short description]
  File: [path/to/file.ext]
  Lines: [start-end]
  Before: [code snippet — the broken version]
  After:  [code snippet — the fixed version]
  Type:   [root-cause-fix | secondary-fix | defensive-fix | cleanup]

Change types:

• root-cause-fix — Directly addresses the root cause of the bug
• secondary-fix — Fixes a related issue discovered during investigation
• defensive-fix — Prevents the same class of bug from recurring
• cleanup — Removed dead code or simplified logic (no behavior change)

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Step 2: Proof Trace (per change)

For EACH change, build a stack-trace-style proof chain — the core of the skill.

Proof Trace Format

PROOF TRACE — Change #N: [description]
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

SYMPTOM (what the user sees):
  → [Observable behavior, e.g., "UI doesn't refresh after assigning PIC"]

TRIGGER PATH (how the symptom occurs):
  1. [file:line] User action → [method/event]
  2. [file:line] → calls [method]
  3. [file:line] → dispatches [action/event]
  4. [file:line] → handler/effect [name]
  5. [file:line] ← BUG HERE: [exact broken behavior]

ROOT CAUSE (proven):
  → [One sentence: what exactly is wrong and why]
  → Evidence: [file:line] shows [specific code proving the bug]
  → Hypothesis matrix mapping: RC-[N] status [primary/contributing/latent] from [report path/section]
  → Feeder paths closed: [path names or "single path verified"]; unresolved paths: [none/list]

FIX MECHANISM (how the change fixes it):
  → [One sentence: what the fix does differently]
  → Before: [broken code path with file:line]
  → After:  [fixed code path with file:line]
  → Owning fix layer: [layer/component] — why this is the lowest shared owner

WHY THIS FIX IS CORRECT:
  → [Reasoning backed by code evidence]
  → Pattern precedent: [file:line] shows same pattern working elsewhere
  → Framework behavior: [file:line or doc reference] confirms expected behavior
  → Forward convergence: [origin/trigger] -> [corrected transformations] -> [observed final output no longer stale/wrong]

EDGE CASES CHECKED:
  → [edge case 1]: [verified/not-verified] — [evidence]
  → [edge case 2]: [verified/not-verified] — [evidence]

SIDE EFFECTS:
  → [None / List of potential side effects with evidence]

CONFIDENCE: [X%]
  Verified: [list of verified items]
  Not verified: [list of unverified items, if any]

Proof Trace Rules

1. Every arrow (→) MUST ATTENTION have a file:line reference — no exceptions
2. TRIGGER PATH must be traceable — someone should be able to follow it step-by-step in the code
3. Hypothesis matrix mapping is REQUIRED for bugfixes — every fix part maps to a primary/contributing/latent root cause or is flagged as unrelated scope
4. Feeder paths must be accounted for — prove the fix closes every path that can write the final observed state, or explicitly list remaining unverified paths
5. Pattern precedent is REQUIRED — find at least 1 working example of the same pattern elsewhere in the codebase
6. Edge cases MUST ATTENTION be enumerated — at minimum: error path, null/empty input, concurrent access
7. Side effects MUST ATTENTION be assessed — what else could this change affect?
8. Spec-loop evidence is REQUIRED for a complete proof (canonical: SYNC:spec-loop-discipline) — the proof MUST carry, with file:line: (a) the regression property TC guarding the fixed invariant — a universally-quantified property ("for ALL inputs in {domain}, {invariant} holds") + boundary counter-case, not just the reproduction example; (b) mutation-kill evidence for the fixed core-logic line — show a surviving mutant on that line is now killed (MUTATION-SCORE bar, not line-coverage %); (c) a Dual-Feedback entry — the spec rule restored/added AND the guarding test that feeds it back. A proof trace missing any of (a)/(b)/(c) is INCOMPLETE — cap its confidence below the 80% ship threshold until the spec-loop evidence is supplied.

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Step 3: Confidence Scoring

Each change gets an individual confidence score:

Score	Meaning	Action Required
95-100%	Full proof trace complete, all edge cases verified, pattern precedent found	Ship it
80-94%	Main proof trace complete, some edge cases unverified	Ship with caveats noted
60-79%	Proof trace partial, some links unverified	Flag to user — recommend additional investigation
<60%	Insufficient evidence	BLOCK — do not proceed until evidence gathered

Scoring Criteria

Award points for each verified item:

Criterion	Points	Evidence Required
Root cause identified with file:line	+25	Code reference
Fix mechanism explained with before/after	+20	Code diff
Pattern precedent found in codebase	+15	Working example at file:line
Framework behavior confirmed	+10	Framework source or docs
Edge cases checked (per case)	+5 each	Verification result
Side effects assessed	+10	Impact analysis
No regressions identified	+5	Test results or code analysis

Total possible: 100+ (normalize to percentage)

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Step 4: Cross-Verification

After individual proof traces, perform cross-change verification:

1. Interaction check — Do the changes interact with each other? Could one change break another?
2. Completeness check — Does the combined fix address ALL reported symptoms?
3. Regression check — Could the combined changes introduce new bugs?
4. Dependency check — Are there other code paths that depend on the changed behavior?
5. Performance regression check — Does the fix introduce performance issues?

[IMPORTANT] Database Performance Protocol (MANDATORY):

1. Paging Required — ALL list/collection queries MUST ATTENTION use pagination. NEVER load all records into memory. Verify: no unbounded GetAll(), ToList(), or Find() without Skip/Take or cursor-based paging.
2. Index Required — ALL query filter fields, foreign keys, and sort columns MUST ATTENTION have database indexes configured. Verify: entity expressions match index field order, database collections have index management methods, migrations include indexes for WHERE/JOIN/ORDER BY columns.

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Step 5: Final Verdict

Produce a summary verdict:

FIX VERIFICATION VERDICT
━━━━━━━━━━━━━━━━━━━━━━━

Overall Confidence: [X%]

Changes Summary:
  #1: [description] — [X%] ✅/⚠️/❌
  #2: [description] — [X%] ✅/⚠️/❌
  #N: [description] — [X%] ✅/⚠️/❌

Symbols: ✅ ≥80% (ship) | ⚠️ 60-79% (flag) | ❌ <60% (block)

Remaining Risks:
  - [risk 1]: [likelihood] × [impact] — [mitigation]
  - [risk 2]: [likelihood] × [impact] — [mitigation]

Verification Method:
  - [Manual testing required? Which scenarios?]
  - [Automated tests cover this? Which tests?]
  - [Additional monitoring needed post-deploy?]

Recommendation: [SHIP / SHIP WITH CAVEATS / INVESTIGATE FURTHER / BLOCK]

Goal Satisfaction update (MANDATORY after verdict): resolve the active Goal Contract per SYNC:goal-contract-satisfaction-loop and map each proof trace to the saved success criterion it satisfies. Append proof evidence and remaining gaps to the goal file's Iteration Log and update its Goal Satisfaction matrix (PASS/FAIL/BLOCKED per criterion). A SHIP recommendation does NOT close the work while any required goal criterion remains FAIL — route the validated gap into another bounded fix loop or escalate a blocker.

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Example: Proof Trace for NgRx Effect Fix

PROOF TRACE — Change #1: Move catchError inside switchMap
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

SYMPTOM:
  → UI doesn't refresh after assigning PIC, Job Opening, or changing stage

TRIGGER PATH:
  1. candidate-quick-card-v2.component.ts:445 — User clicks "Assign PIC"
  2. candidate-card.container.component.ts:892 — onPersonInChargeChange($event)
  3. candidate-card.effect.ts:275 — SavePersonInCharge effect
  4. candidate-card.effect.ts:284 — dispatches LoadCandidateDetailsAction
  5. candidate-card.effect.ts:48 ← EFFECT IS DEAD — never processes the action

ROOT CAUSE:
  → catchError at outer pipe level (effect.ts:64) causes effect completion on ANY error
  → Evidence: effect.ts:43-69 shows catchError OUTSIDE switchMap
  → Evidence: ngrx-effects.js:156-165 confirms defaultEffectsErrorHandler
     only catches errors, not completions

FIX MECHANISM:
  → Move catchError INSIDE switchMap so errors are caught per-request
  → Before: effect.ts:64 — catchError at outer pipe → effect COMPLETES → DEAD
  → After:  effect.ts:52 — catchError inside switchMap → inner obs completes → outer SURVIVES

WHY THIS FIX IS CORRECT:
  → RxJS: catchError inside switchMap catches per-emission, outer stream continues
  → Pattern precedent: effect.ts:120 (moveApplicationToNextState) uses same inner pattern
  → Framework: NgRx effects auto-resubscribe on ERROR but NOT on COMPLETION

EDGE CASES:
  → 403 Forbidden: verified — returns SetCandidateDetails with isAllowDisplayed=false
  → Network timeout: verified — returns EMPTY, effect survives
  → Multiple rapid requests: verified — switchMap cancels previous (unchanged)

SIDE EFFECTS:
  → None — same error handling logic, only scope changed

CONFIDENCE: 95%
  Verified: root cause, fix mechanism, pattern precedent, framework source, all edge cases
  Not verified: behavior under specific proxy/auth middleware errors (very unlikely)

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Run python .claude/scripts/code_graph trace <file> --direction downstream --json to prove fix doesn't break downstream.

Graph Intelligence (RECOMMENDED if graph.db exists)

If .code-graph/graph.db exists, enhance analysis with structural queries:

• Verify test coverage: python .claude/scripts/code_graph query tests_for <function> --json
• Trace affected code paths: python .claude/scripts/code_graph query callers_of <function> --json
• Batch analysis: python .claude/scripts/code_graph batch-query file1 file2 --json

Graph-Trace for Fix Verification

When graph DB is available, use trace to PROVE the fix doesn't break downstream consumers:

• python .claude/scripts/code_graph trace <fixed-file> --direction downstream --json — verify all downstream consumers, event handlers, and bus message listeners are unaffected
• python .claude/scripts/code_graph trace <fixed-file> --direction both --json — full context: what triggered the bug (upstream) + what the fix affects (downstream)
• Include trace results as evidence in the proof chain

Integration with Other Skills

This skill is the mandatory verification gate between /fix and /code-simplifier in fix workflows.

Workflow position:

... → /fix → /prove-fix → /code-simplifier → /review-changes → ...

If proof trace reveals issues:

• Score ≥80%: proceed to next step
• Score 60-79%: ask user whether to proceed or investigate further
• Score <60%: BLOCK — return to /debug-investigate or /fix step

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$ARGUMENTS

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Workflow Recommendation

MANDATORY IMPORTANT MUST ATTENTION — NO EXCEPTIONS: If you are NOT already in a workflow, you MUST ATTENTION use AskUserQuestion to ask the user. Do NOT judge task complexity or decide this is "simple enough to skip" — the user decides whether to use a workflow, not you:

1. Activate workflow-bugfix workflow (Recommended) — scout → investigate → debug → plan → fix → prove-fix → review → test
2. Execute /prove-fix directly — run this skill standalone

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Next Steps

MANDATORY IMPORTANT MUST ATTENTION — NO EXCEPTIONS after completing this skill, you MUST ATTENTION use AskUserQuestion to present these options. Do NOT skip because the task seems "simple" or "obvious" — the user decides:

• "/code-simplifier (Recommended)" — Clean up fix implementation
• "/integration-test" — Generate/update regression integration tests
• "/workflow-review-changes" — Review all changes before commit
• "Skip, continue manually" — user decides

[IMPORTANT] Use TaskCreate to break ALL work into small tasks BEFORE starting — including tasks for each file read. This prevents context loss from long files. For simple tasks, AI MUST ATTENTION ask user whether to skip.

Prerequisites: MUST ATTENTION READ before executing:

• docs/project-reference/domain-entities-reference.md — Domain entity catalog, relationships, cross-service sync (read when task involves business entities/models)

External Memory: For complex or lengthy work (research, analysis, scan, review), write intermediate findings and final results to a report file in plans/reports/ — prevents context loss and serves as deliverable.

Evidence Gate: MANDATORY IMPORTANT MUST ATTENTION — every claim, finding, and recommendation requires file:line proof or traced evidence with confidence percentage (>80% to act, <80% must verify first).

End-to-Start Debugger Trace — For non-trivial bugs, failed verification, regression fixes, behavior-changing code, or unclear code flow, start from the observed final state and walk backward before proposing a fix.

1. Frame 0: observed end state — Name the exact user-visible output, failing assertion, log line, persisted value, API response, rendered UI, or aggregate bucket. Record the reader/query/renderer that produced it with file:line evidence.
2. Walk backward one hop at a time — Trace final reader -> projection/cache/storage -> writer -> consumer/handler/job -> producer/caller -> original trigger. At every hop record: input, transformation, output, owner, and evidence.
3. Enumerate all feeder paths — Find every upstream producer/caller/event/job that can write into the final path, including retry, async, cache, background, and alternate UI/API paths. Mark each path verified, ruled out, or still unknown.
4. Build the hypothesis matrix — For each plausible cause, list evidence for, evidence against, how to reproduce/verify, blast radius, and status (primary, contributing, ruled out, latent). Do not fix until competing causes are explicitly resolved or bounded.
5. Choose the owning fix layer — Identify the invariant owner and the lowest shared point that protects all downstream consumers. A fix at the symptom site is rejected unless the symptom site owns the invariant.
6. Prove convergence forward — After choosing the fix, walk start -> end again and show how the corrected state reaches the observed final output. Map each root cause to a fix part and each fix part to a test/proof.

BLOCKED until: final state named · backward trace written · all feeder paths enumerated · hypothesis matrix completed · owning fix layer justified · forward convergence proof mapped to tests.

NEVER: Start at the first suspicious code path. Collapse multiple producers into one "flow". Treat duplicate symptoms as duplicate records without proving the read model. Skip ruled-out hypotheses.

UI System Context — For ANY task touching .ts, .html, .scss, or .css files:

MUST ATTENTION READ before implementing:

1. docs/project-reference/frontend-patterns-reference.md — component base classes, stores, forms
2. docs/project-reference/scss-styling-guide.md — BEM methodology, SCSS variables, mixins, responsive
3. docs/project-reference/design-system/README.md — design tokens, component inventory, icons

Reference docs/project-config.json for project-specific paths.

Graph-Assisted Investigation — MANDATORY when .code-graph/graph.db exists.

HARD-GATE: MUST ATTENTION run at least ONE graph command on key files before concluding any investigation.

Pattern: Grep finds files → trace --direction both reveals full system flow → Grep verifies details

Task	Minimum Graph Action
Investigation/Scout	trace --direction both on 2-3 entry files
Fix/Debug	callers_of on buggy function + tests_for
Feature/Enhancement	connections on files to be modified
Code Review	tests_for on changed functions
Blast Radius	trace --direction downstream

CLI: python .claude/scripts/code_graph {command} --json. Use --node-mode file first (10-30x less noise), then --node-mode function for detail.

Critical Thinking Mindset — Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence >80% to act. Anti-hallucination: Never present guess as fact — cite sources for every claim, admit uncertainty freely, self-check output for errors, cross-reference independently, stay skeptical of own confidence — certainty without evidence root of all hallucination.

Understand Code First — HARD-GATE: Do NOT write, plan, or fix until you READ existing code.

1. Search 3+ similar patterns (grep/glob) — cite file:line evidence
2. Read existing files in target area — understand structure, base classes, conventions
3. Run python .claude/scripts/code_graph trace <file> --direction both --json when .code-graph/graph.db exists
4. Map dependencies via connections or callers_of — know what depends on your target
5. Write investigation to .ai/workspace/analysis/ for non-trivial tasks (3+ files)
6. Re-read analysis file before implementing — never work from memory alone. — why: long context drifts from the file; the file is ground truth
7. NEVER invent new patterns when existing ones work — match exactly or document deviation. — why: divergent patterns fragment the codebase and slow every future reader

BLOCKED until: - [ ] Read target files - [ ] Grep 3+ patterns - [ ] Graph trace (if graph.db exists) - [ ] Assumptions verified with evidence

Fix-Layer Accountability — NEVER fix at the crash site. Trace the full flow, fix at the owning layer.

AI default behavior: see error at Place A → fix Place A. This is WRONG. The crash site is a SYMPTOM, not the cause.

MANDATORY before ANY fix:

1. Trace full data flow — Map the complete path from data origin to crash site across ALL layers (storage → backend → API → frontend → UI). Identify where the bad state ENTERS, not where it CRASHES.
2. Identify the invariant owner — Which layer's contract guarantees this value is valid? That layer is responsible. Fix at the LOWEST layer that owns the invariant — not the highest layer that consumes it.
3. One fix, maximum protection — Ask: "If I fix here, does it protect ALL downstream consumers with ONE change?" If fix requires touching 3+ files with defensive checks, you are at the wrong layer — go lower.
4. Verify no bypass paths — Confirm all data flows through the fix point. Check for: direct construction skipping factories, clone/spread without re-validation, raw data not wrapped in domain models, mutations outside the model layer.

BLOCKED until: - [ ] Full data flow traced (origin → crash) - [ ] Invariant owner identified with file:line evidence - [ ] All access sites audited (grep count) - [ ] Fix layer justified (lowest layer that protects most consumers)

Anti-patterns (REJECT these):

• "Fix it where it crashes" — Crash site ≠ cause site. Trace upstream.
• "Add defensive checks at every consumer" — Scattered defense = wrong layer. One authoritative fix > many scattered guards.
• "Both fix is safer" — Pick ONE authoritative layer. Redundant checks across layers send mixed signals about who owns the invariant.

Source/test drift check. For coding, fix, debug, investigation, test, or review work: when source behavior changes, inspect affected unit/integration/E2E tests and decide from evidence whether tests should change to match intended behavior or the source change is an unintended bug to fix. Do not write tests for migration code; schema/data migrations are one-time execution paths, not core application logic.

AI Mistake Prevention — Failure modes to avoid on every task:

Re-read files after context changes. Context compaction, resume, or long-running work can make memory stale; verify current files before acting. Verify generated content against source evidence. AI hallucinates APIs, names, claims, and document facts. Check the relevant source before documenting or referencing. Check downstream references before deleting or renaming. Removing an artifact can stale docs, generated mirrors, configs, and callers; map references first. Trace the full impact chain after edits. Changing a definition can miss derived outputs and consumers. Follow the affected chain before declaring done. Verify ALL affected outputs, not just the first. One green check is not all green checks; validate every output surface the change can affect. Assume existing values are intentional — ask WHY before changing. Before changing a constant, limit, flag, wording, or pattern, read nearby context and history. Surface ambiguity before acting — don't pick silently. Multiple valid interpretations require an explicit question or stated assumption with risk. Keep shared guidance role-relevant. Universal guidance must help every receiving skill or agent; code-specific obligations belong only in code-specific protocols.

IMPORTANT MUST ATTENTION search 3+ existing patterns and read code BEFORE any modification. Run graph trace when graph.db exists.

• MANDATORY IMPORTANT MUST ATTENTION cite file:line evidence for every claim. Confidence >80% to act, <60% = do NOT recommend.

IMPORTANT MUST ATTENTION read frontend-patterns-reference, scss-styling-guide, design-system/README before any UI change.

IMPORTANT MUST ATTENTION run at least ONE graph command on key files when graph.db exists. Pattern: grep → graph trace → grep verify.

IMPORTANT MUST ATTENTION trace full data flow and fix at the owning layer, not the crash site. Audit all access sites before adding ?..

MUST ATTENTION apply critical + sequential thinking — every claim needs appropriate traced evidence (file:line for repo/code claims; source URL or artifact section for research, product, content, and docs claims); confidence >80% to act, <60% DO NOT recommend. Anti-hallucination: never present guess as fact, admit uncertainty freely, cross-reference independently, stay skeptical of own confidence.

MUST ATTENTION apply AI mistake prevention — verify generated content against evidence, trace downstream references before deleting or renaming, verify all affected outputs, re-read files after context loss, and surface ambiguity before acting.

IMPORTANT MUST ATTENTION debugger trace gate: for non-trivial bug/fix/investigation/review work, start at the observed final output and trace backward through reader -> storage/projection -> writer -> consumer/job -> producer/trigger. Enumerate all feeder paths and hypotheses before fixing. BLOCKED until trace, hypothesis matrix, owning fix layer, and forward convergence proof exist.

• MANDATORY Resolve the active Goal Contract BEFORE work (active plan goal.md → plans/goals/{YYMMDD-HHmm}-{slug}/goal.md → create from current request) and read saved success criteria before editing.
• MANDATORY Append iteration evidence after execution; emit a Goal Satisfaction matrix (PASS/FAIL/BLOCKED) before reporting PASS; loop on validated FAIL; escalate repeated no-progress or blockers. NEVER store secrets in goal files.

Prompt-Enhance Closing Anchors

IMPORTANT MUST ATTENTION follow declared step order for this skill; NEVER skip, reorder, or merge steps without explicit user approval IMPORTANT MUST ATTENTION for every step/sub-skill call: set in_progress before execution, set completed after execution IMPORTANT MUST ATTENTION every skipped step MUST include explicit reason; every completed step MUST include concise evidence IMPORTANT MUST ATTENTION if Task tools unavailable, maintain an equivalent step-by-step plan tracker with synchronized statuses

Closing Reminders

IMPORTANT MUST ATTENTION Goal: block shipping an unproven fix — build a file:line proof trace (debugger-style: symptom → root cause → fix mechanism → why-correct → edge cases → side effects) and confidence score per change, so a fix ships only when correctness is PROVEN (≥80%), never assumed.

Protocols in force (concise digest of the SYNC/shared blocks this skill carries):

• End-to-Start Trace: start at observed output, trace backward, hypothesis matrix before fixing.
• UI System Context: read frontend-patterns, scss-styling, design-system before any UI change.
• Graph Investigation: run ≥1 graph command on key files when graph.db exists.
• Critical Thinking: traced file:line proof per claim; confidence >80% to act.
• Understand Code First: grep 3+ patterns and read code before any modification.
• Fix-Layer Accountability: trace full data flow, fix at owning layer not crash site.
• Source/Test Drift: when source behavior changes, reconcile affected unit/integration/E2E tests from evidence.
• AI Mistake Prevention: verify generated content against evidence, trace downstream references, verify all affected outputs, re-read after context loss, surface ambiguity.

IMPORTANT MUST ATTENTION every arrow (→) in every proof trace MUST ATTENTION carry a file:line reference — no exceptions; a claim without traced evidence is speculation and BLOCKS the ship. — why: a proof chain with an unproven link proves nothing. IMPORTANT MUST ATTENTION score each change with the points rubric (root cause +25, fix mechanism +20, pattern precedent +15, framework +10, edge cases +5 each, side effects +10, no regressions +5) → ≥80% ship · 60-79% flag to user · <60% BLOCK; NEVER ship a <80% change — route it back to /debug-investigate or /fix. — why: the threshold is the gate; bypassing it defeats the skill. IMPORTANT MUST ATTENTION run AFTER /fix, never before — this is the non-negotiable verification gate between /fix and /code-simplifier; NEVER skip it because the fix "looks obviously right". — why: obviousness is the exact illusion this gate exists to break.

Domain protocols this proof MUST NOT skip:

IMPORTANT MUST ATTENTION pattern precedent is REQUIRED, not optional — cite at least 1 working example of the same pattern at file:line elsewhere in the codebase; "no precedent found" caps confidence below 80%. — why: a fix with no precedent is an unproven invention. IMPORTANT MUST ATTENTION edge cases are REQUIRED — enumerate at minimum error path, null/empty input, concurrent access, each verified with evidence; assess side effects (what else this change touches). — why: the happy path passing is not the change being correct. IMPORTANT MUST ATTENTION spec-loop evidence is REQUIRED for a complete proof (SYNC:spec-loop-discipline) — (a) a regression PROPERTY TC (∀ inputs in {domain}, invariant holds) + boundary counter-case, (b) mutation-kill evidence on the fixed line (MUTATION-SCORE, not line-coverage %), (c) a Dual-Feedback entry (spec rule restored + guarding test); missing any one caps confidence below 80%. — why: line coverage and a single reproduction example let the original defect class survive. IMPORTANT MUST ATTENTION map every fix part to a primary/contributing/latent root cause from the hypothesis matrix and prove ALL feeder paths are closed; fix at the LOWEST shared owning layer, NEVER patch the crash/symptom site. — why: a symptom-site patch leaves the real cause writing bad state through other paths. IMPORTANT MUST ATTENTION for non-trivial bug/fix work, start at the observed final output and trace BACKWARD (reader → storage/projection → writer → consumer/job → producer/trigger) before proposing a fix; build the hypothesis matrix first. — why: starting at the first suspicious line fixes a symptom, not the cause. IMPORTANT MUST ATTENTION run the Database Performance Protocol in cross-verification — ALL list/collection queries paginated (no unbounded GetAll/ToList/Find), ALL filter/FK/sort columns indexed. — why: a correct fix that degrades query performance ships a new regression. IMPORTANT MUST ATTENTION when .code-graph/graph.db exists, run a trace --direction downstream on the fixed file to prove no downstream consumer breaks; include trace output as proof evidence. — why: a green local change can silently break a distant caller. IMPORTANT MUST ATTENTION resolve the active Goal Contract AFTER the verdict (SYNC:goal-contract-satisfaction-loop) — map each proof trace to its success criterion, emit the PASS/FAIL/BLOCKED matrix; a SHIP verdict does NOT close work while any required criterion remains FAIL. — why: a verified change is not a satisfied goal. MANDATORY IMPORTANT MUST ATTENTION break work into small TaskCreate todos BEFORE starting (one task per change/proof), keep exactly one in_progress, add a final review todo; on context loss first — resume, never duplicate.

Anti-Rationalization:

Evasion	Rebuttal
"Fix is obviously correct, skip the proof"	Obviousness is the illusion this gate breaks. Build the trace anyway — every arrow file:line.
"No precedent, but it's clearly right"	No precedent caps confidence <80%. Find a working example or mark the change unproven.
"Reproduction test passes, that's enough"	A single example ≠ a property. Add the universally-quantified regression TC + boundary case.
"Line coverage is green"	Coverage ≠ kill. Show the surviving mutant on the fixed line is now killed (mutation score).
"I'll just patch where it crashes"	Crash site ≠ cause site. Trace backward, fix the lowest invariant owner that protects all paths.
"Score is 75%, close enough to ship"	<80% BLOCKS. Flag to user or return to /debug-investigate — never round a confidence up.

IMPORTANT MUST ATTENTION run AFTER /fix only; every arrow carries file:line; score ≥80% to ship, <60% BLOCK — these three are the gate. (primacy-recency echo of the top three)

[TASK-PLANNING] Before acting, analyze task scope and break it into small TaskCreate todos systematically before starting — this is very important.