documentation

---
name: documentation
description: Feature documentation and release notes patterns. Use when documenting changes, writing PR descriptions, or preparing releases.
---

# Documentation

## PR Description

Use the repository template at `.github/pull_request_template.md` — read the FULL file before drafting (the required sections continue past the first screen). CI (`.github/workflows/pr-lint.yml`) fails any PR whose description is missing one of these exact headings:

- `## Details`
- `## Change checklist`
- `## Issues`
- `## Testing`
- `## Documentation`

Also fill in the template's `## AI-WATERMARK` section (yes/no; if yes: Tools, Model(s), Scope, Human verification). Never invent a different structure such as `## Summary` / `## Test Plan`.

A section that does not apply gets `N/A` — never delete a heading.

### `## Details` — style

Write what changes for a user. A reviewer reads the diff for the code; this section tells them what is different when they use the product.

- **Short.** Most PRs need 3–10 bullets. If it runs longer, the section is doing the diff's job — cut it.
- **Bullets, not prose paragraphs.** One behavior per bullet. Nest one level for sub-cases.
- **Authoritative.** State what happens: "The run is scored once." Not "This should now mean that the run will be scored once."
- **No fluff.** No motivation paragraph, no "this PR …", no approach summary, no benefits list, no restating the diff.
- **Observable behavior first.** What the UI shows, what the API returns, what gets scored, stored or logged. Name a class, method or file only when the behavior makes no sense without it.

Pick the shape that fits the change — do not force one:

- **Before / After bullet lists** when a behavior changed and the contrast is the point.
- **A flat bullet list** for a new capability, where there is no "before".
- **One or two lines** when users cannot see the change (refactor, dependency bump) — say what is unchanged and what improved, then stop.

## Changelog Entry

```markdown
### [VERSION] - [DATE]

#### New Features
- **Feature Name**: Brief description

#### Improvements
- **Improvement**: What changed and why

#### Bug Fixes
- **Fix**: What was broken (#issue)

#### Breaking Changes
- **Change**: What breaks, migration steps
```

## Feature Documentation

When documenting a feature, cover:

**User Impact**
- What capability does this add?
- How do users access it?

**Technical Changes**
- API changes (endpoints, params)
- SDK changes (new methods)
- Database migrations
- Config changes

**Breaking Changes** (if any)
- What breaks
- Migration steps

## Key Files

- `apps/opik-documentation/documentation/fern/docs-v2/self-host/changelog.mdx` - Self-hosted deployment changelog (breaking/critical changes only; the former repo-root `CHANGELOG.md` was removed)
- `apps/opik-documentation/documentation/fern/docs-v2/changelog/` - Main product docs changelog entries (dated `.mdx` files)
- `apps/opik-documentation/documentation/fern/docs-v2/development/optimization-runs/changelog.mdx` - Agent Optimizer release changelog
- `apps/opik-documentation/documentation/fern/docs.yml` - Docs routing/navigation source of truth for changelog surfaces
- `.github/release-drafter.yml` - Release template

## Changelog Routing Rules

- Pick the changelog target by scope; do not default everything to one surface.
- Use `apps/opik-documentation/documentation/fern/docs-v2/self-host/changelog.mdx` only for self-hosted deployment breaking/critical/security-impacting notes.
- Use `apps/opik-documentation/documentation/fern/docs-v2/changelog/*.mdx` for general Opik product release notes shown in `/docs/opik/changelog`.
- Use `apps/opik-documentation/documentation/fern/docs-v2/development/optimization-runs/changelog.mdx` for Agent Optimizer version updates (for example `sdks/opik_optimizer` releases like `3.1.0`).
- Liquibase `changelog.xml` files are migration manifests, not user-facing release-note changelogs.
- If unsure where an entry belongs, confirm the surface from `apps/opik-documentation/documentation/fern/docs.yml` before editing.

## Images in documentation

- **Use `fern/img`** for documentation images (e.g. `apps/opik-documentation/documentation/fern/img/...`).
- **Do not use `static/img`** for new assets; it is a legacy folder used by external integrations and cannot be deleted.
- Reference images in docs as `/img/...` (e.g. `/img/tracing/openai_integration.png`).
- In repos that define `docs.yaml`/`docs.yml`, treat that file as the routing source of truth; do not assume URLs mirror directory layout.

## Internationalized READMEs

Non-English README files (`readme_CN.md`, `readme_ES.md`, `readme_FR.md`, `readme_DE.md`) are AI machine-translated from the English `README.md`.

- Each non-English README must have a notice at the top (as a blockquote) warning that the file is AI-translated and welcoming improvements.
- When the English README is updated with significant content changes, re-translate the affected non-English READMEs using AI and update accordingly.
- Do not manually edit translated READMEs for content changes; update the English source and re-translate.

## Style

- User perspective, not implementation details
- Specific (version numbers, dates)
- Code examples for API/SDK changes
- Concise - link to docs, don't duplicate

More agent context in comet-ml/opik

20 other files this repository gives its agents.