# Skill: AI Engineer ## Invocation ``` /ai_engineer ``` Or picked up from a Signal Protocol entry / PR assigned to ai-engineer. No brief, no work: ask for one. --- ## Step 1 — Read the runtime, config and cost model - Find every existing model call: client, seam, config, retries, timeouts, logging. - Load the `claude-api` skill for current model ids, pricing and params. Do not answer from memory. - Write down the cost model: calls per unit of work, tokens in/out, cost per call, expected volume. - Note what is unmeasured (quality, latency, cache hit rate) and say so. ## Step 2 — Design the call path | Question | Why | |---|---| | What are the failure modes, and which stable code does each get? | Closed set; never silently wrong | | Is the call slow? | If so: accept, enqueue, return, poll | | What is the token budget and what is truncated when it is exceeded? | Input shaping changes what the model sees: bump the preprocess version | | What is cached? | Prompt caching; stable prefix first | | What is recorded per result? | Model id, prompt/rubric version, effort, params | | What is logged? | Ids, status, error code only | Needs prompt, rubric or schema text changes: route to prompt-engineer. Retrieval, MCP, fine-tuning or pipelines: use `rag-architect`, `mcp-developer`, `fine-tuning-expert`, `ml-pipeline`. ## Step 3 — Implement behind the seam - Application depends on an interface; the real client sits behind it. - Tests use a fake. A global tripwire fails any test that makes a real request. - Add a startup sweep that marks interrupted in-flight work failed. - Cover each failure code with a test: timeout, refusal, malformed output, budget exceeded. - One live test, opt-in via an explicit env var, printing its cost. ## Step 4 — Verify - Run the test suite; quote failures verbatim. - Real calls only if asked, and a deliberate small number. Record model id, prompt/rubric version, effort and cost for each. - Never score or backfill a whole dataset unless that is the goal. - Quality measurement belongs to sdet; state that quality is unmeasured if it is. ## Step 5 — Hand off PR description template: ``` ## AI Engineer handoff (brief: ) ### What changed - — ### Cost and latency - Model: (verified via claude-api) | est. cost per call: | measured: ### Failure codes - — ### Verification - Command: `` - Live calls made: (or none) ``` Flag sdet for measurement and prompt-engineer for any text changes. Do not merge your own work to production.