Companion to **o2-enterprise #2157**. Opt-in, **OFF by default**. When
an OSS PR **merges**, this caller dispatches the DocGen engine
automatically.
### Gate (all must hold)
- `github.event.pull_request.merged == true`
- title starts with `feat:`
- same-repo branch (fork guard)
- **`vars.DOCGEN_AUTO_TRIGGER == 'true'`** (opt-in)
- `vars.DOCGEN_DISABLED != 'true'`
### How
- `on:` adds `pull_request: [closed]`; the job `if:` gains the auto path
(manual `/docgen` + dispatch unchanged).
- `ctx` resolves the `pull_request` event → full run, actor = PR author,
`auto=true`, and passes `-f auto` so the engine **suppresses the
"waiting for merge" comment** on the auto path.
- The ack comment stays manual-only, so the auto path is silent until
the docs PR lands.
Nothing fires until `DOCGEN_AUTO_TRIGGER=true` is set on both repos.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>