Merge pull request #417 from tmchow/docs/eval-not-in-ci-solution

docs: capture eval-not-in-CI design decision under docs/solutions/
This commit is contained in:
Trevin Chow
2026-05-16 22:31:39 -07:00
committed by GitHub
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---
title: Search-quality eval is manual by default, not a CI gate on every PR
date: 2026-05-10
category: docs/solutions/architecture
module: skills/last30days/scripts/evaluate_search_quality.py
problem_type: design_decision
component: ci_policy
severity: low
applies_when:
- a contributor proposes wiring search-quality eval into PR CI
- a change affects retrieval, ranking, grounding, or synthesis quality and a reviewer asks "why aren't we testing this in CI?"
- someone is deciding whether a new evaluator-style script belongs in the default CI workflow
related_components:
- search_quality_evaluation
- ci_workflow
- llm_judging
tags:
- ci-policy
- eval
- design-decision
- cost-vs-signal
- non-determinism
- manual-gates
---
# Search-quality eval is manual by default, not a CI gate on every PR
## Context
`skills/last30days/scripts/evaluate_search_quality.py` compares a baseline revision against a candidate revision across a fixed pool of reviewer topics. It produces two flavors of metrics: deterministic overlap (Jaccard, retention) and LLM-judged quality scores. The natural impulse on seeing an evaluator script is to wire it into CI on every PR — "regression catcher, run it automatically." We deliberately don't.
Three properties of this particular evaluator make CI-on-every-PR the wrong default:
1. **Live API access.** The candidate revision typically needs the engine to actually run, which means real ScrapeCreators calls, real reddit fetches, real YouTube searches. CI runs would either need production credentials or a record/replay fixture set that drifts almost immediately as external APIs change shape.
2. **Cost and latency.** A full eval pass runs the pipeline N times across reviewer topics. Multiplied by every PR (including doc-only PRs), the spend is meaningful and the wall-clock pushes CI from ~30s to many minutes.
3. **Non-determinism in the judging path.** The LLM-judged metrics are valuable for review but depend on judge-model behavior on a given day. A flaky eval that fails 1 PR in 20 because the judge re-scored an item differently is a worse CI signal than no eval at all — it teaches contributors to retry rather than read the result.
The deterministic overlap metrics are useful regression signals but they are not the same as user-facing correctness. A change that improves overlap can degrade synthesis quality; a change that drops overlap can be a deliberate improvement. So even the deterministic side isn't safe to auto-fail on.
## Guidance
### 1. Keep search-quality eval available, just not automatic
The script stays runnable by maintainers and contributors. The pattern is:
```bash
LAST30DAYS_PYTHON=python3.13 \
python3 skills/last30days/scripts/evaluate_search_quality.py \
--baseline main --candidate HEAD
```
Reviewers can request a manual eval run when a PR is in the retrieval/ranking/synthesis path and the risk warrants it. Contributors can run it locally before submitting if they want signal upfront.
### 2. Standard PR CI gates remain deterministic and contract-shaped
`pytest` (offline-safe), plugin-contract checks, version-consistency contracts, ruff/lint. Anything that returns the same answer twice for the same input. Quality-of-output assessment lives outside that loop.
### 3. The middle ground is `workflow_dispatch`, not auto-PR-gating
If maintainers want a GitHub-triggered eval that doesn't make every PR pay the live-API cost, the right shape is a manually-dispatched workflow (or a label-triggered one) — not a `pull_request:` workflow that runs unconditionally. That keeps the cost knob in human hands.
### 4. Revisit if the eval can ever be made offline-deterministic
The blocker is the live-API + non-determinism combination. If a future iteration of the script can compute meaningful Jaccard/retention metrics against static fixtures (no live API calls, no LLM judging), the decision flips and it becomes a candidate for default CI. The decision below tracks that condition; revisit when it's met.
## What this means in practice
- Don't merge PRs that wire `evaluate_search_quality.py` into the default `validate.yml` workflow.
- Do merge PRs that add `workflow_dispatch` triggers or label-gated runs.
- When reviewing a retrieval/ranking change, request a manual eval if the diff suggests it could regress quality — don't expect CI to catch it.
## Links
- `skills/last30days/scripts/evaluate_search_quality.py` — the evaluator script
- `docs/search-quality-eval.md` — user-facing usage documentation
- `.github/workflows/validate.yml` — the default CI workflow (deterministic gates only)
---
*Adapted from a draft ADR proposed by @hnshah in [#374](https://github.com/mvanhorn/last30days-skill/pull/374), restructured into the `docs/solutions/` convention. The original ADR text correctly identified the constraint; this version adds the "why workflow_dispatch is the middle ground" framing and the revisit-condition.*