create-evlog-adapter

name	create-evlog-adapter
description	Create a new built-in evlog adapter to send wide events to an external observability platform. Use when adding a new drain adapter (e.g., for Datadog, Sentry, Loki, Elasticsearch, etc.) to the evlog package. Covers source code, build config, package exports, tests, and all documentation.

Create evlog Adapter

Add a new built-in adapter to evlog. Every adapter follows the same architecture. This skill walks through all 8 touchpoints. Every single touchpoint is mandatory -- do not skip any.

PR Title

Recommended format for the pull request title:

feat: add {name} adapter

The exact wording may vary depending on the adapter (e.g., feat: add OTLP adapter, feat: add Axiom drain adapter), but it should always follow the feat: conventional commit prefix.

Touchpoints Checklist

#	File	Action
1	packages/evlog/src/adapters/{name}.ts	Create adapter source
2	packages/evlog/tsdown.config.ts	Add build entry
3	packages/evlog/package.json	Add exports + typesVersions entries
4	packages/evlog/test/adapters/{name}.test.ts	Create tests
5	apps/docs/content/3.adapters/{n}.{name}.md	Create adapter doc page (before custom.md)
6	apps/docs/content/3.adapters/1.overview.md	Add adapter to overview (links, card, env vars)
7	AGENTS.md	Add adapter to the "Built-in Adapters" table
8	Renumber custom.md	Ensure custom.md stays last after the new adapter

Important: Do NOT consider the task complete until all 8 touchpoints have been addressed.

Naming Conventions

Use these placeholders consistently:

Placeholder	Example (Datadog)	Usage
{name}	datadog	File names, import paths, env var suffix
{Name}	Datadog	PascalCase in function/interface names
{NAME}	DATADOG	SCREAMING_CASE in env var prefixes

Step 1: Adapter Source

Create packages/evlog/src/adapters/{name}.ts.

Read references/adapter-template.md for the full annotated template.

Key architecture rules:

1. Config interface -- service-specific fields (API key, endpoint, etc.) plus optional timeout?: number
2. getRuntimeConfig() -- import from ./_utils (shared helper, do NOT redefine locally)
3. Config priority (highest to lowest):
   • Overrides passed to create{Name}Drain()
   • runtimeConfig.evlog.{name}
   • runtimeConfig.{name}
   • Environment variables: NUXT_{NAME}_* then {NAME}_*
4. Factory function -- create{Name}Drain(overrides?: Partial<Config>) returns (ctx: DrainContext) => Promise<void>
5. Exported send functions -- sendTo{Name}(event, config) and sendBatchTo{Name}(events, config) for direct use and testability
6. Error handling -- try/catch with console.error('[evlog/{name}] ...'), never throw from the drain
7. Timeout -- AbortController with 5000ms default, configurable via config.timeout
8. Event transformation -- if the service needs a specific format, export a to{Name}Event() converter

Step 2: Build Config

Add a build entry in packages/evlog/tsdown.config.ts alongside the existing adapters:

'adapters/{name}': 'src/adapters/{name}.ts',

Place it after the last adapter entry (currently sentry at line 22).

Step 3: Package Exports

In packages/evlog/package.json, add two entries:

In exports (after the last adapter, currently ./posthog):

"./{name}": {
  "types": "./dist/adapters/{name}.d.mts",
  "import": "./dist/adapters/{name}.mjs"
}

In typesVersions["*"] (after the last adapter):

"{name}": [
  "./dist/adapters/{name}.d.mts"
]

Step 4: Tests

Create packages/evlog/test/adapters/{name}.test.ts.

Read references/test-template.md for the full annotated template.

Required test categories:

1. URL construction (default + custom endpoint)
2. Headers (auth, content-type, service-specific)
3. Request body format (JSON structure matches service API)
4. Error handling (non-OK responses throw with status)
5. Batch operations (sendBatchTo{Name})
6. Timeout handling (default 5000ms + custom)

Step 5: Adapter Documentation Page

Create apps/docs/content/3.adapters/{n}.{name}.md where {n} is the next number before custom.md (custom should always be last).

Use the existing Axiom adapter page (apps/docs/content/3.adapters/2.axiom.md) as a reference for frontmatter structure, tone, and sections. Key sections: intro, quick setup, configuration (env vars table + priority), advanced usage, querying in the target service, troubleshooting, direct API usage, next steps.

Step 6: Update Adapters Overview Page

Edit apps/docs/content/3.adapters/1.overview.md to add the new adapter in three places (follow the pattern of existing adapters):

1. Frontmatter links array -- add a link entry with icon and path
2. ::card-group section -- add a card block before the Custom card
3. Zero-Config Setup .env example -- add the adapter's env vars

Step 7: Update AGENTS.md

In the root AGENTS.md file, "Log Draining & Adapters" section:

1. Add a row to the "Built-in Adapters" table
2. Add a "Using {Name} Adapter" usage example block with create{Name}Drain() and env vars

Follow the pattern of existing adapters in the file.

Step 8: Renumber custom.md

If the new adapter's number conflicts with custom.md, renumber custom.md to be the last entry. For example, if the new adapter is 5.{name}.md, rename 5.custom.md to 6.custom.md.

Verification

After completing all steps, run:

cd packages/evlog
bun run build    # Verify build succeeds with new entry
bun run test     # Verify tests pass