Page 3 of 8~112 min topic

Eval gates in code

Build the first working CI eval release gate

Page 3 implements the shortest complete path for the release eval gate in CI with inspectable intermediate values.

~14 min this pageImplementation

1Learn the idea

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Implement the minimal working path

Build only what the claim requires: gate exits non-zero on regression and zero on the pinned baseline. Prefer boring, deterministic code over frameworks you cannot yet explain. Run the path twice; identical output on this fixture is a feature, not a lack of creativity.

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Run the working path

def run_case(case, *, release, trace_id):
    # Adapters are injected in production; the orchestration owns policy.
    answer = staging_agent(case["question"], request_id=trace_id)
    reasons = evaluate(answer if "answer" in locals() else locals().get("result", locals().get("decision", locals().get("job", locals().get("choice")))))
    return {"passed": not reasons, "reasons": reasons,
            "release": release, "trace_id": trace_id}

result = run_case({"id":"refund-window","question":"Can I return headphones after 20 days?","must_include":["30 days","receipt"],"must_not_include":["no returns"],"severity":"critical"}, release="candidate", trace_id="trace-42")
assert result["trace_id"] == "trace-42"

Expected evidence: the new prompt omits the 30-day refund window while producing fluent prose. Read each printed intermediate as part of the argument that the path works—not as decoration.

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Trace one input end to end

Narrate the journey from raw input to result for a single example from golden JSONL + threshold.yaml. If you cannot name an intermediate, the implementation is still too opaque for this lab. Only after this path is solid should you generalize data sources or UI.

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Lab notebook: intermediates worth printing

While implementing the CI eval release gate, print or log at least three intermediates that map to the claim (gate exits non-zero on regression and zero on the pinned baseline). Good intermediates are values a teammate could recompute with a calculator or diff. Bad intermediates are framework traces you cannot explain.

Re-run with golden JSONL + threshold.yaml twice. If the second run differs, either the path is nondeterministic (document the seed) or you have hidden global state—both are lab bugs until named.

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Worked judgment

Stop adding features once the path supports fail a candidate release when golden-task metrics regress past a pinned threshold. Extra UI, extra tools, or extra models belong in later chapters. The mastery bar for this page is simply: a deterministic end-to-end path with intermediates.

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Why this stage matters for the CI eval release gate

At the implementation stage for eval-in-code, the job is narrower than finishing a product demo. You are creating one progressive evidence piece about golden JSONL + threshold.yaml that later pages inherit without redefining success. Keep that fixture small enough to inspect by hand, keep outputs copy-pasteable as text, and refuse to narrate this baseline as if it were a production SLA: last known good release metrics.

For this page specifically, success looks like a deterministic path with printed intermediates while still centering the user decision to fail a candidate release when golden-task metrics regress past a pinned threshold. If you cannot point to a file, command, or assertion that proves that for the CI eval release gate, stay on this page instead of advancing.

How-to: ship agent with eval gate · Glossary: eval set

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Before you start

Why this matters

Without running code, predict the final output for fixture golden JSONL + threshold.yaml. Name one intermediate value that would prove the prediction. Then answer: what could look successful while actually being wrong at this stage for the CI eval release gate?

In the wild

See how this idea shows up as a product and a company — then come back to the lesson. Skills transfer across vendors.

Check your understanding

Page assessment

Answer from memory. Completion is saved from this evidence, not from opening the next page.

1. Can you narrate every intermediate value?
2. Is the fixture deterministic and independently inspectable?
3. Did you avoid framework behavior you cannot explain yet?
4. Does the output still support the decision: fail a candidate release when golden-task metrics regress past a pinned threshold?

All responses are required.