eval-writer

name	eval-writer
description	Turn acceptance criteria into a runnable Smithers eval suite (JSONL cases + rubric) and wire it to `smithers eval`. Use when a workflow's quality must be measured and regression-tested — not "looks good" once, but a repeatable check that fails when the model OR the harness regresses.

Eval Writer

This skill is about the backpressure layer: the suite that pushes evidence back against the agent's claim that a workflow is done. A single passing run proves nothing repeatable. An eval suite turns acceptance criteria into cases (input + expected + rubric), runs the whole workflow over them, and exits non-zero when any case regresses. That is the difference between "the agent said it works" and a gate that can fail.

The key insight: an eval evaluates the model AND the harness together. You're not scoring a prompt in isolation — you run the real <Workflow> (its agents, schemas, retries, branches, loops) against fixed inputs and assert on the persisted output. A regression anywhere in that stack — a worse model, a broken prompt, a dropped field, a mis-wired branch — turns a case red.

When to reach for it

• A workflow ships something whose quality matters (release notes, a triage decision, a generated patch) and you need to know if it gets worse next week.
• You're about to accept "looks good" as verification. Encode a check that can fail instead.
• You changed a prompt, swapped a model, or refactored the graph and need to prove you didn't regress behavior.
• You want a baseline to optimize against (smithers optimize runs a suite twice).

Skip it for one-off prompts nothing downstream depends on. Backpressure is for behavior you'll need to hold steady over time.

Cases: input + expected + rubric, as JSONL

A suite is a .jsonl file under .smithers/evals/, one case per line. Each case is an input for the workflow plus an expected assertion. Assertions support status (run reached finished), output (exact match), and outputContains (partial / deep-subset match — the usual choice).

{"id":"happy-path","input":{"prompt":"Draft release notes"},"expected":{"status":"finished"}}
{"id":"lists-breaking-changes","input":{"prompt":"Release notes for v2"},"expected":{"status":"finished","outputContains":{"notes":{"breakingChanges":[{"severity":"high"}]}}}}

Turn each acceptance criterion into at least one case: a happy path, the quality-gate criterion itself, and an adversarial/edge case that should trip a weak run. Keep outputContains keyed to the load-bearing fields of the output schema (see skills/schema-author/SKILL.md) — assert on the typed fields a human would actually check, not on prose.

Run it

bunx smithers-orchestrator eval .smithers/workflows/release.tsx \
  --cases .smithers/evals/release-quality.jsonl \
  --suite release-quality --force

• --suite <name> is a stable ID used in run IDs and the report path; reuse it so runs are comparable over time.
• Report lands at .smithers/evals/<suite>.json; the command exits non-zero on any failure — wire that into CI as the gate.
• --dry-run plans run IDs without launching (cheap shape check before spend).
• -j/--concurrency N runs cases in parallel; --max-cases N smoke-tests a subset.
• --optimization <artifact.json> runs the suite with GEPA-patched prompts.

Attach scorers for graded, non-binary quality

Assertions are pass/fail; scorers grade quality on a Task and run after completion (they never block the run). Attach them to the <Task> whose output you care about, then read them with smithers scores.

import { schemaAdherenceScorer, faithfulnessScorer, relevancyScorer } from "smithers-orchestrator/scorers";
import { llmJudge } from "smithers-orchestrator/scorers";

<Task id="draft" output={outputs.notes} agent={writer}
  scorers={{
    schema:    { scorer: schemaAdherenceScorer() },
    grounded:  { scorer: faithfulnessScorer() },
    onTopic:   { scorer: relevancyScorer() },
    quality:   { scorer: llmJudge({ model: claude, prompt: "Rate completeness 0-1" }),
                 sampling: { kind: "ratio", ratio: 0.1 } },
  }}>
  Draft the release notes.
</Task>

faithfulness (grounded in source), relevancy (on-topic), schemaAdherence (shape held), and llmJudge(...) (rubric-as-judge) are the workhorses. Sample expensive judges with { kind: "ratio", ratio: 0.1 }. Inspect:

bunx smithers-orchestrator scores <run-id>

Use assertions for the hard gate (must-be-true), scorers for the trend (is it getting better or worse).

The automated path: the eval-author workflow

You don't have to hand-write the suite. The seeded eval-author workflow turns plain-English acceptance criteria into a JSONL fixture (id, input, expected, rubric) under .smithers/evals/, then reports the exact smithers eval command:

bunx smithers-orchestrator workflow run eval-author \
  --input '{"prompt":"Release notes must list every breaking change","workflow":".smithers/workflows/release.tsx"}'

Reach for it to bootstrap a suite from criteria, then hand-tighten the cases and add scorers. See skills/smithers/SKILL.md for the runtime/CLI surface and docs/llms-core.txt ("Eval suites for regressions", "Scorers") for the exact report format and the full scorer list.