gap-trap

Sets up a quality framework for repositories where agents write most of the code. Every rule the agents follow has a gate that fails a commit, a push, or a CI run when the rule breaks. A rule a script could check but that names no gate is a defect. The framework is the one described in reference/framework.md; read it before either mode.

Two modes: setup builds the framework in a repo that has none. refine audits a repo that has it and proposes the next rules and gates from what broke. Bare gap-trap with no keyword means setup when the repo has no AGENTS.project.md, otherwise refine. A hand-written AGENTS.md or CLAUDE.md on its own is input to setup, not a sign the framework exists.

Model gate

This skill runs on the top coding model of your harness: in Claude Code, Opus or a more capable model (Opus 4.8 or newer, Opus 5, Fable, Mythos); in Codex, the frontier coding model at high or xhigh reasoning effort. Discovery decides which parts of a codebase get a contract, and a wrong contract costs every later session. Your system prompt names your model.

If it is a cheaper or faster tier (Sonnet, Haiku, a mini model, or low reasoning effort), stop. Read nothing, write nothing. Say exactly this and end the turn:

gap-trap runs on the top coding model of this harness. You are on . Switch with /model, then run gap-trap again.

Do not dispatch stronger subagents from a weaker orchestrator, start "the easy parts", or offer a lighter version.

setup

1. Discover. Follow reference/discovery.md. It produces a plan file in your scratch directory: stack, commands, CI provider, contract candidates with real symbol names, the first domain facts from history (the revert probe runs at any commit count), and one row per rule found in an existing instruction file with where it goes and what gates it.
2. Confirm once. Show the plan as a short list: the contracts you will write (at most six), the gates you will add, the test and lint commands you found, the migrated-rules table, and where slop-mop goes. A build, type check, or lint that is already red is the first item: setup fixes only what its own gate files need (a missing type package, a lockfile) and records the rest as a ratchet count or an out-of-scope entry. Name the cause of each red before recording it: reproduce it, read the failure, and say what is broken. A failure that names an environment variable can still be a code defect. In one trial, seven tests failing with Environment variable not found: DATABASE_URL were a Prisma mock loaded after the module under test, not a missing .env; recording that as an environment gap would have buried the bug and the contract that prevents it. Ask one round of questions, only about what discovery could not settle. Then proceed.
3. Install slop-mop. git clone https://github.com/pliablepixels/slop-mop.git into your scratch directory and copy slop-mop/slop-mop to the skills directory of the harness you are running in (Claude Code: ~/.claude/skills/; Codex: ~/.agents/skills/), skipping it if present. It is not vendored into the repo; the project rule in AGENTS.project.md requires it. A harness loads its skill list when the session starts, so a skill installed here is not available to the run that installed it: write this run's prose from P10 in AGENTS.md, and tell the user in the report that slop-mop applies from their next session.
4. Write the instruction files from templates/. AGENTS.md and agents/generic/agent-workflows.md are copied unchanged, with one exception: a rule whose gate cannot exist in this repo (I3's accessibility lint and C3's locales in a repo with no UI) gets its Gate: clause replaced by Gate: n/a, no <thing> in this repo. Nothing else in AGENTS.md changes. AGENTS.project.md, CLAUDE.md, and agents/project/ are filled from the plan; drop the UI and end-to-end lines and {{E2E_CMD}} when the repo has no UI, and delete every placeholder you cannot fill with a verified value. Contracts name real symbols only. Existing instruction files (AGENTS.md, CLAUDE.md, .cursorrules, .github/copilot-instructions.md, CONTRIBUTING.md) are migrated from the plan's migrated-rules table, one row at a time: a contract row becomes a contract block, a rule row becomes a project rule with its gate name or Gate: review, a playbook row goes verbatim into the named agents/project/ file, a command row fills the verification block, and a duplicate or dropped row is left out. No rule is dropped silently; the confirm step showed the table. A file whose name a template owns (AGENTS.md, CLAUDE.md) is replaced by that template. Any other instruction file (.cursorrules, .github/copilot-instructions.md) becomes a one-line pointer to AGENTS.md, so the agent that reads it lands on the rules instead of a stale copy. CONTRIBUTING.md stays where it is. The user sees the diff.
5. Write the gates from reference/gates.md, in the repo's own test runner and CI provider: the instruction gate, proven red, the PR body check, the ratchet (always, seeded with the counters the repo supports: files over the C2 length, lint problems per rule when a linter runs, each contract Never clause that has violations today), and the mutation smoke when discovery named a risky module (auth, a parser, the API client); otherwise refine adds it after the first fix chain. The stack table there picks the reference: native ports for Node and Python, shell references that need only git, grep, and awk for every other language. Set the instruction gate's word budget at the current count plus half, rounded up to the next 500.
6. Prove each gate red with a scratch violation, remove the violation, run the repo's full test command, and commit one logical change per commit, in this order: the instruction files with the gate that checks them; one commit per gate after that (ratchet, proven red, mutation smoke, PR body check); the combined gate command and the pre-commit hook; CI last. One commit holding the whole framework hides which gate was proven red against what, and leaves nothing to revert on its own. Do not push unless asked.
7. Report what was written, the instruction word count against the budget, which contracts say Gate: review and why, whether this run installed slop-mop and so it applies from the next session, any always-loaded file outside the repo whose prose style conflicts with the repo's (~/.codex/AGENTS.md, ~/.claude/CLAUDE.md, a terse or compressed house style): name the file, and say that the repo's rule governs repo prose. End with the one next step: run gap-trap refine after the first incident or in a month.
8. Offer a check. End the report with one question: check the repo against the new framework now? On no, stop. On yes, change no files and list, grouped by contract or rule ID:
   • each ratchet counter, its count, and the file and line behind each unit of it;
   • each Gate: review contract: read the code its Path: and Never: lines cover and list suspected violations with file and line, marked unverified because no gate checks them;
   • the red build, type check, or lint items recorded in step 2. Fix nothing in this pass. A fix the user picks is its own commit, and a fix that lowers a count reruns the ratchet with --update.

Instruction files are read by agents. Write them as terse statements with IDs and gate names. Human-voice prose belongs in the repo's docs, not in AGENTS*.md or agents/.

refine

Follow reference/refine.md. It audits rules without gates, contract names that no longer exist, and the commit history since the last refine, and it proposes edits through the self-improvement protocol as one PR. It removes rules with no incident behind them as readily as it adds gates.

Common mistakes

Mistake	Fix
A contract with a guessed symbol name	Every name in a Path: line is greppable in the tree; the instruction gate fails otherwise
Writing ten contracts on day one	Start with the places that have one sanctioned path and a violation today; add the rest through refine
A gate that passed on first run	Prove it red with a scratch violation first; a gate that never failed proves nothing
Vendoring slop-mop into the repo	It installs per agent from its repo; the project rule requires it
Instruction prose polished for people	Agents read it. Statement, one-clause why, gate name
Skipping the model gate because the repo is small	Discovery quality is the deliverable; the gate is first for a reason