Find Layer Violation

/find-layer-violation

You are the orchestrator for a layer-violation audit. Your job is to drive a detector + a scout-verification fan-out; the judgment calls (is this business logic or HTTP plumbing, which service owns the domain, is the dispatch bypass intentional) live in the scout brief and the knowledge files, not in this prompt.

The four buckets (extract_service, move_to_existing_service, broad_workflow_coordinator, intentional_http_coupling), the View-Pattern evaluation rule, and the extraction-sketch format are documented in knowledge/verification.md — scouts read it, you don't.

How success is judged

• Every reported entry point carries a Stage 3 scout verdict at scout/<candidate_id>.json — an authority judgment in one of the four buckets (extract_service / move_to_existing_service / broad_workflow_coordinator / intentional_http_coupling), not a raw signal count.
• The closeout pastes the real Stage 1/2/4 stderr lines ([detect_layer_violation], [collapse], [report]) plus the scout JSON count; claims without those artifacts do not satisfy the audit.
• Extract-service candidates in report.md are actionable: their IDs resolve as /fix-workflow layer:<candidate_id> arguments; coordinators route to product-topology mapping instead.
• Zero code edits — read-only audit. Write toward these gates from Stage 0.

Scope

• Target path: the required --target argument. View and task layer files within it are classified automatically (by the conventional views/tasks segment names, or the host's .engineering/docs/find-layer-violation-scope.md layer map). Accepts a directory for a full sweep or a single file.
• Project root: this worktree's root.
• Python: .venv/bin/python (detectors are stdlib-only, but this repo runs them through the venv for consistent tooling).
• Project-specific defaults (LOC budgets, HTTP-coupled exemptions, existing-service inventory): in knowledge/.
• Responsibility-left-in-view rule: for omnibus views, measure what authority remains in the view after extraction: raw SQL, direct API client use, direct model writes, task dispatch, export construction, filesystem writes, and cross-model transactions. LOC is only the first signal.
• Coordinator rule: if a view coordinates workflow context, sidebar/dashboard status, template selection, and compatibility redirects but delegates domain behavior to services, classify it as broad_workflow_coordinator. Its next step is usually /map-product-workflow or /extract-workflow-registry, not a domain-service extraction.

Pipeline stages (each has a contract)

Each stage reads files the previous stage wrote and writes files the next stage reads. Run scripts with .venv/bin/python and capture stderr so failures surface.

Stage 0 — Setup

Pre: none. Post: ${REPORT_DIR} exists, latest symlink points to it.

TS=$(date +%Y%m%d-%H%M%S)
REPORT_DIR="reports/layer-violation/scan-${TS}"
mkdir -p "${REPORT_DIR}/scout"
ln -sfn "scan-${TS}" reports/layer-violation/latest

Stage 1 — Detect

Pre: target directory exists. Post: layer_violations.jsonl with one record per signal-hit (score-sorted).

.venv/bin/python .claude/skills/find-layer-violation/scripts/detect.py \
  --target <target> \
  --project-root "$(pwd)" \
  --output "${REPORT_DIR}/layer_violations.jsonl"

Stage 2 — Collapse

Pre: layer_violations.jsonl. Post: ${REPORT_DIR}/candidates.jsonl — per-symbol candidates with candidate_id assigned, capped to top 30.

A single method often fires 2–4 signals; collapse groups by (file, symbol) and assigns a confidence tier (high = 3+ signals, medium = 2, low = 1).

.venv/bin/python .claude/skills/find-layer-violation/scripts/collapse.py \
  --detections "${REPORT_DIR}/layer_violations.jsonl" \
  --output "${REPORT_DIR}/candidates.jsonl" \
  --top 30

Stage 3 — Verify (parallel fan-out)

Pre: candidates.jsonl. Post: ${REPORT_DIR}/scout/<candidate_id>.json for every verified candidate.

This is the only stage where LLM judgment runs. Dispatch one sub-agent per top-10 candidate (or fewer if the candidate list is shorter). Each sub-agent receives:

• the candidate JSON (one line from candidates.jsonl),
• the prompt template from agents/verify.md,
• paths to knowledge/* files,
• an output path it must write to.

Budget: verify up to the top 10 candidates by default. If the user asked for a deeper scan, raise the budget. If the user asked for a specific subset (e.g., "only the tasks"), filter before dispatch.

For each candidate, expand agents/verify.md (substitute {{candidate_id}}, {{candidate_json}}, {{project_root}}, {{skill_root}}, {{output_path}}) and dispatch with subagent_type=general-purpose. Send all Agent calls in a single message so they run concurrently.

Declare the verdict to every scout: its output is accepted only if it writes valid JSON at {{output_path}}, uses one of the four buckets, accounts for every detector signal in signals_confirmed or signals_dismissed, and gives interface_depth_note for service extractions. When merging, reject or re-dispatch malformed scout files; do not let report.py turn an unverified candidate into an actionable layer handoff.

If a scout returns invalid JSON or flags the verification as aborted, re-dispatch once with a stricter "respond only with file-write confirmation" nudge; skip the candidate if it fails twice.

Dispatch mode — Agent tool vs cheap subprocess

This skill declares scout_model: cheap — the verify step is read-and- classify against the four buckets in verify.md (extract_service / move_to_existing_service / broad_workflow_coordinator / intentional_http_coupling). The scout reads the enclosing function and checks the existing-service inventory in knowledge/, no cross- file synthesis, no shell. Safe on Haiku-class scouts.

For nesting-safe + low-cost fan-out, dispatch each candidate as a tools/code_agent.py --read-only subprocess via .claude/skills/_common/dispatch_scout_cheap.sh. The --read-only flag drops bash, spawn_agent, claude_tools, and validate_jsonld — the scout has only read_file/write_file/glob/grep, with workdir containment enforced (commit 168ca3c1). Cheap models can't hallucinate calls to tools that aren't in the registry.

# One subprocess per candidate; parallelize with `&` + wait.
while read -r line; do
    cid=$(jq -r '.candidate_id' <<<"$line")
    out="${REPORT_DIR}/scout/${cid}.json"
    .claude/skills/_common/dispatch_scout_cheap.sh \
        .claude/skills/find-layer-violation/agents/verify.md \
        "$out" \
        candidate_id="$cid" \
        candidate_json="$(jq -c . <<<"$line")" \
        project_root="$(pwd)" \
        skill_root=".claude/skills/find-layer-violation" \
        output_path="$out" &
done < "${REPORT_DIR}/candidates.jsonl"
wait

Tradeoffs. Cheap subprocess dispatch adds 2-4s spawn per scout and runs Claude Haiku 4.5 through the team's Expedient gateway by default (see tools/agent-config.json); set DISPATCH_SCOUT_MODEL to swap in any other alias (e.g., cerebras for personal-account free-tier capacity). The Agent tool path is faster (0s spawn) and uses the orchestrator's session model (Sonnet/Opus tier — more judgment, billed). Use the cheap subprocess by default; fall back to Agent when (a) only a handful of candidates need verification interactively and the user is watching, or (b) a candidate is genuinely ambiguous between broad_workflow_coordinator and extract_service and the better model's judgment about workflow ownership is worth the cost.

Stage 4 — Report

Pre: candidates.jsonl, scout/*.json. Post: ${REPORT_DIR}/report.md and ${REPORT_DIR}/findings.json.

.venv/bin/python .claude/skills/find-layer-violation/scripts/report.py \
  --candidates "${REPORT_DIR}/candidates.jsonl" \
  --scout-dir "${REPORT_DIR}/scout" \
  --output-md "${REPORT_DIR}/report.md" \
  --output-json "${REPORT_DIR}/findings.json" \
  --scan-id "scan-${TS}" \
  --target <target>

# Effectiveness log — one line per run, feeds reports/_meta/dashboard.md.
.venv/bin/python scripts/log_effectiveness.py \
  --skill find-layer-violation \
  --scan-id "scan-${TS}" \
  --target <target> \
  --findings-total "$(.venv/bin/python -c 'import json,sys; d=json.load(open(sys.argv[1])); print(d.get("summary",{}).get("findings_total", len(d.get("findings", []))))' "${REPORT_DIR}/findings.json")" \
  --buckets "$(.venv/bin/python -c 'import json,sys; print(json.dumps(json.load(open(sys.argv[1])).get("summary",{}).get("buckets", {})))' "${REPORT_DIR}/findings.json")"

Stage 5 — Summarize

Report to the user in ≤10 lines:

• counts by bucket (extract_service / move_to_existing_service / broad_workflow_coordinator / intentional_http_coupling / unverified),
• top 3 candidates (one line each: file, symbol, signal list, recommendation),
• path to ${REPORT_DIR}/report.md and the latest symlink,
• recommended next slash command — for the worst confirmed candidate, /fix-workflow layer:<candidate_id>. That skill reads the candidate and drives the extraction through characterization tests and two-commit discipline. For broad_workflow_coordinator, recommend product-topology mapping before code movement.

The report is the source of truth — do not enumerate every candidate.

Replay case

When detect.py, collapse.py, report.py, or the scout JSON schema changes, replay a disposable Python target with one view function that loops over a queryset, writes two model types, and dispatches a task. Expected evidence: Stage 1 writes at least one layer_violations.jsonl record with multiple signals; Stage 2 collapses it to one candidate; after a hand-written scout JSON that accounts for every signal and buckets it as extract_service, Stage 4 writes report.md and findings.json with one actionable layer finding.

Non-goals

• Executing the extraction (that's /fix-workflow after user approval).
• Editing or deleting code — read-only audit.
• Detecting duplication (that's /find-duplication / /find-semantic-duplication).
• Detecting omnibus modules (that's /find-omnibus).
• Enforcing LOC budgets on every commit (that's scripts/lint/no_fat_view.py, the fat-view rule — diff-scoped per-commit check). This skill is the broader periodic audit, which also covers domain_loop, direct_llm_call, dispatch_bypass, and multi_model_write.
• CI gates — periodic audit, not a per-commit check.

When things go sideways

Repository layout

.claude/skills/find-layer-violation/
├── SKILL.md                  # this file — orchestrator
├── scripts/
│   ├── detect.py             # Stage 1 — AST signal detector
│   ├── collapse.py           # Stage 2 — per-symbol grouping + ids
│   └── report.py             # Stage 4 — render report.md + findings.json
├── agents/
│   └── verify.md             # Stage 3 scout brief
└── knowledge/                # sub-agent context, never loaded by orchestrator
    └── verification.md

The orchestrator (you) never reads files in knowledge/. Those are for the scout sub-agents. Keeping them out of your context is the whole point of this architecture.