Security And Hardening
Audits a code diff for security vulnerabilities before it can ship. MUST run as a fresh, code-cold reviewer on every Implement diff in the Review fan-out — and any time code touches user input, auth, sessions, secrets, data storage, external/URL fetches, file uploads, or LLM output. A CRITICAL/HIGH finding or a secret in the diff is a hard STOP: the slice is halted, never opened as a PR.
Test Driven Development
Rigid RED-GREEN-REFACTOR test-first loop. Use when implementing ANY feature or bugfix inside a slice, before writing one line of production code — turns each signed acceptance.md scenario into a test you watch fail first. If you're about to write impl, or about to "just relax a failing test so it passes," stop and load this.
Environment Manifest
Capture every external thing the autonomous run needs — API keys, MCP servers, services, runtime deps, test fixtures, accounts — as a typed-kind manifest with NO values and NO commands. Use during Spec right after the PRD lands, and again during Plan once slices exist. ALWAYS run this before an AFK/autonomous wave so preflight-readiness can refuse to start on a missing dependency. If you are abou…
Incremental Implementation
Builds one assigned slice as thin, individually-tested vertical increments — skeleton-first (stub→mock→wire→fill), simplicity-first, test-first. Use the moment you start writing code for a planned slice, and ESPECIALLY when you're tempted to write more than ~100 lines before running a test, land a whole feature in one pass, "clean up" code outside the slice, or weaken a test to get green. Runs in…
Pull Request
Open a design-anchored DRAFT pull request that ENDS a slice — turn green, reviewed code into it, then STOP. Reach for this the moment a slice's three internal gates are green (qa.md pass · review fan-out clear · evaluator floors met). It anchors the Summary to prd.md + ADRs (NEVER a commit-log dump), names the 3-5 highest-risk files as a mandatory reviewer code-reading checklist, builds the test…
Browser Testing With Devtools
Tests in real browsers via whatever browser-automation MCP is configured (Chrome DevTools, Claude-in-Chrome, Playwright, or agent-browser) — the live-runtime engine the quality-verification skill drives. Use when building, debugging, or verifying anything that runs in a browser, or when you need to inspect the DOM, capture console errors, analyze network requests, profile performance, or verify v…
Using Agent Skills
The meta-dispatcher for the achilles-skills suite. Maps any task to the right stage skill and the artifact-chain lifecycle (Ideate → Spec → Plan → Implement → Verify → Review → Ship). Use this FIRST — at the start of every session and whenever you are unsure which skill applies — before writing any plan, spec, or code. Acting without consulting this index is how the wrong skill gets run and the a…
Deprecation And Migration
Removes code that no longer earns its keep and migrates users off it safely. Use this the moment you''re about to delete, sunset, or replace an old system, API, feature, or duplicate implementation — and STOP before deleting anything: this skill makes you measure usage, build the replacement first, and migrate consumers so you don''t leave users stranded. Use when consolidating duplicates, when f…
Debugging And Error Recovery
Stop-the-line root-cause debugging. Use the MOMENT a test fails, a build breaks, behavior contradicts an expectation, or any unexpected error appears — before you write another line. Do NOT guess at a fix or patch the symptom; run the five-step triage (reproduce, localize, reduce, fix, guard). This is the engine `incremental-implementation` reaches for when a slice's tests break and `quality-veri…
To Prd
Synthesize the grilled intent + design substrate into a product-altitude prd.md — NO interview, just synthesis of what you already discussed. Reach for this the moment intent.md is pinned and the ADRs are written and you need the dual-audience product spec the whole pipeline reads. STAY at product altitude: reference ADRs by id, use CONTEXT.md terms verbatim, and NEVER paste a file path, signatur…
Quality Verification
Proves a finished slice actually works before it ships — a fresh, code-cold, maker≠checker Verify pass. Reach for this the moment a slice reaches `verify` — it exercises every signed acceptance.md scenario against the running app, runs the design gate against frontend-design's signed contract (UI only), drives the browser-testing-with-devtools engine, and writes qa.md with an exercised/not-reacha…
Doubt Driven Development
In-flight adversarial review — subjects every non-trivial decision to a fresh-context reviewer biased to disprove, not approve, BEFORE it stands. Use during Plan and Implement (not at the merge gate) when correctness outweighs speed, when working in unfamiliar code, when stakes are high (production, security-sensitive logic, irreversible operations), or any time a confident output would be cheape…
Documentation And Adrs
The repo's ADR and documentation STANDARD — capture the WHY (context, constraints, rejected alternatives), not just the what. Reach for this whenever you make a hard-to-reverse architectural decision, supersede an old one, change a public API, ship a user-facing feature, or record context a future engineer or agent will need. spec-grilling, codebase-design, api-design, and the Ship skills all def…
Interview Me
Extracts what the user actually wants instead of what they think they should want. Achieves this through one-question-at-a-time interview until ~95% confidence about the underlying intent. Use when an ask is underspecified ("build me X" without "for whom" or "why now"), when the user explicitly invokes ("interview me", "grill me", "are we sure?", "stress-test my thinking"), when you catch yoursel…
Worktree
Use the instant a slice is about to be implemented and needs its own isolated, clean-baseline workspace — BEFORE any code is written. Detects existing isolation first (never double-nests, never fights the harness), prefers a native worktree tool over raw `git worktree add`, installs deps, and proves the test baseline is green so new failures are distinguishable from old ones. If you are about to…
Ci Cd
Stands up and hardens the quality-gate CI/CD pipeline so no change reaches production without passing lint, types, tests, build, and audit. Use when setting up or modifying build/deploy pipelines, automating quality gates, configuring test runners or branch protection in CI, debugging CI failures, or deciding a deployment/feature-flag/rollback strategy. Reach for this whenever a change should tri…
Observability And Instrumentation
Instruments code so production behavior is visible and diagnosable from the outside. Use the moment you add logging, metrics, tracing, or alerting — and as you build ANY feature that runs in production and will need evidence it works. Instrument as you build, not after the first incident becomes archaeology. Use when a production issue is reported but the telemetry can't tell you what happened. R…
Source Driven Development
Ground every framework- or library-specific decision in official docs you actually fetched — never in training-data memory. Use the moment you are about to write version-sensitive code (routing, forms, data fetching, auth, state, config, build setup): detect the installed version from the dependency file, deep-link the matching doc page, follow it exactly, and cite the full URL. Use whenever corr…
Code Simplification
Reduce code complexity without changing behavior — the Review-stage QUALITY axis. Use the moment a slice''s code is green but reads heavier than it should: deep nesting, nested ternaries, dead code, generic names, copy-paste duplication, speculative abstractions. Apply Chesterton''s Fence (understand before you cut) and stay scoped to what changed. Quality only — it does NOT hunt for bugs (that i…
Spec Grilling
Use BEFORE writing any PRD or design doc — whenever the user wants to design a feature from an idea or intent.md, stress-test a design, pin down domain terminology, surface design decisions the user hasn't considered, or record an architectural decision. Interview relentlessly, ONE question at a time, with a recommended answer each. Emits ADRs + CONTEXT.md; never a PRD.
Spec Review
Use this LAST in the Spec stage, before the human signs off — a fresh code-cold agent that FIXES the spec instead of listing complaints. You MUST run it after spec-grilling/to-prd/acceptance-criteria/environment-manifest (and frontend-design for UI) land and before the Spec gate. It auto-fixes decidable facts (stray file paths/signatures in prd.md, dangling `see ADR-NNN`, non-verbatim CONTEXT ter…
Shipping And Launch
Prepares production releases and authors the launch runbook. Use the moment you are preparing to ship to production, batching merged PRs into a release, or anyone asks for a pre-launch checklist, a feature-flag rollout, a staged/canary rollout plan, monitoring setup, or a rollback strategy. In the v1 autonomous run this AUTHORS the runbook only — it never fires deploy/rollout/rollback commands it…
Frontend Design
Use whenever you build or reshape ANY UI surface — a page, screen, component, or flow. Explore throwaway variants, commit ONE high-fidelity prototype as the reference-spec build target, and write the signed design contract that Verify grades against. Invoke BEFORE any production UI; don't reach for a cream-serif-terracotta default.
Preflight Readiness
Environment-readiness gate that blocks an autonomous wave until every environment.md manifest row is provisioned — runs at the human→AFK boundary right after environment.md is signed and BEFORE the orchestrator dispatches slice one. Probes every manifest row with a read-only, value-blind prober and REFUSES to start the wave on any red or un-attested amber — never optimistically. Re-fire mid-run a…
Acceptance Criteria
Turn a prd.md into acceptance.md — the Given/When/Then prose contract that is the SOLE human-anchored oracle for the entire autonomous run. Reach for this the MOMENT a prd.md exists and BEFORE any planning, TDD, or QA — test-driven-development and quality-verification REFUSE to run without a signed acceptance.md. If you are about to write "acceptance criteria", "definition of done", test scenario…
Api Design
Designs stable, hard-to-misuse interface contracts BEFORE implementation — the types ARE the spec. Reach for this the moment plan-breakdown needs to pin a module boundary, a REST or GraphQL endpoint, a component prop interface, or a cross-module type contract: define the contract first, validate only at boundaries, prefer addition over modification, and treat every observable behavior as a commit…
Handoff
Compact the current session into a cold-start handoff the MOMENT context fills, the work pauses, or you are about to /clear — so a fresh agent resumes from durable state, not a lost conversation. Writes the 5-field handoff, references artifacts by path instead of duplicating them, and redacts every secret. Use BEFORE you lose context, not after.
Orchestrator
Drives the autonomous Implement→Verify→Review→Ship loop once the human-owned Spec+Plan is signed and STATE.md holds a slice DAG. Use it to run a build AFK — it sorts slices into topological waves, runs each wave's ready slices in parallel (one worktree per slice, disjoint files only), holds a barrier until every slice reaches a TERMINAL state (done/halted/blocked — never just "success"), and ends…
Code Review
Five-axis code review — correctness, readability, architecture, security, performance — INCLUDING test quality, with severity-labeled findings (Critical/Required/Optional/Nit/FYI) and change-sizing. Reach for this BEFORE any slice's PR opens; never eyeball a diff. Use whenever you review code written by yourself, another agent, or a human, or whenever the orchestrator dispatches the Review fan-ou…
Idea Refine
Refine a raw or half-formed idea into a sharp, buildable concept through structured divergent-then-convergent thinking, always surfacing hidden assumptions and an explicit "Not Doing" list. Use this in the Ideate stage BEFORE Spec whenever an idea is still vague, whenever you are tempted to jump straight to a plan without stress-testing it, or whenever you want to expand options before converging…
Performance Optimization
Measure-first performance review of a code change. Use the moment a slice''s diff touches data fetching, rendering, bundle size, or any hot path, or when Core Web Vitals / load-time budgets are in play. Do NOT eyeball performance: profile the running app, cite before/after numbers, and flag N+1 queries, unbounded fetches, oversized bundles, and needless re-renders before the PR opens.
Codebase Research
Map the codebase/DB exactly as it is today — a goal-blind, fact-only survey produced by parallel read sub-agents that never see the design — BEFORE anyone writes plan.md. Use this the moment Plan starts, whenever someone says "research the codebase," "do the codebase dive," or is tempted to plan against a guess about how the code works. Skip it and plan-breakdown plans on fiction.
Codebase Design
Shared vocabulary and method for designing deep modules — a lot of behaviour behind a small interface, at a clean seam, testable through it. Use when planning a module's interface during plan-breakdown, when the user wants to design or improve an interface, find deepening opportunities, decide where a seam goes, make code more testable or AI-navigable, or when another skill needs the deep-module…
Plan Breakdown
THE planner — turns a signed prd.md + research.md into a concrete, agent-executable plan.md. Reach for it the moment Plan starts and someone says "plan this", "break it into tasks", "write the implementation plan", or is tempted to hand the build agent a prose sketch. Produces vertical tracer-bullet slices (each demoable, cross-layer, with an observable checkpoint) where every non-trivial step na…
Project Setup
Scaffolds the repo ecosystem every achilles skill assumes — a one-time bootstrap that creates the STATE.md board, the CONTEXT.md glossary, docs/adr/, and docs/features/, and — when the repo has neither a CLAUDE.md nor an AGENTS.md and you opt to create CLAUDE.md — seeds it from a bundled behavioral template. Run this ONCE before the first feature, before interview-me or spec-grilling. The pipelin…
Git Workflow
Trunk-based git discipline — atomic save-point commits (~100 lines, one logical change), short-lived branches, descriptive why-not-what messages, and a hard secret scan before every commit. Use this BEFORE every commit, branch, merge, or revert. Git is always on: if you are about to write code or type `git commit`, you are already in this skill''s scope. Skipping it means giant unreviewable commi…