Trigger docs deploy via repository_dispatch instead of a Vercel hook

[somacdivad]

Source and scope

Requirement: a merge to this repo's main must trigger a fresh deployment of the docs website. This is the templates-repo half; it pairs with docs-repo PR RelationalAI/relationalai-docs#864, which adds the matching repository_dispatch trigger. Merge order doesn't matter — this dispatch is a harmless no-op until #864 is on the docs repo's main.

Why not the Vercel deploy hook it replaces

The public docs site is published by relationalai-docs' Vercel branch deploys pipeline: vercel build --prod → validate → deploy candidate → publish the prod_relationalai_docs Algolia index → vercel promote → verify. The docs project has Vercel git-deploy disabled (vercel.json → "git": { "deploymentEnabled": false }) precisely because deploys are meant to go through that pipeline. The old curl "$VERCEL_HOOK_MAIN" triggered a Vercel-side build that bypasses the indexing/validation/promote steps, so it can't correctly publish the site.

What changed

• Renamed vercel-main-deploy-hook.yml → trigger-docs-deploy.yml.
• On push to main, it now fires a repository_dispatch (event_type: templates-updated) to relationalai/relationalai-docs via gh api, instead of curling the Vercel hook. That runs the docs repo's real public deploy pipeline, which re-clones templates main during templates:sync and republishes.

Why

Templates content is pulled into the docs site at build time; with the docs project's git-deploy disabled, a merge here otherwise never reached the live site. Dispatching the docs pipeline closes that gap correctly.

Risks

• Token scope: DOCS_REPO_TOKEN must be allowed to create a repository_dispatch on relationalai-docs (contents: write). It's already used here to check out that repo (read); if it lacks write, the gh api call returns 404/403 and the step fails visibly.
• Assumption about the old hook: I treated VERCEL_HOOK_MAIN as targeting the public/main docs deployment (its name, vs. the separate VERCEL_HOOK_PRIVATE the docs repo uses for the private site). If that secret was load-bearing for something else, flag it in review — it becomes unused after this change.
• Every main merge now triggers a full public redeploy (Algolia reindex + promote). Intended, but higher deploy volume.

How to verify

1. Merge this and #864.
2. Push a trivial change to main here; confirm this workflow runs and the gh api … /dispatches step succeeds.
3. Confirm a Vercel branch deploys run starts in relationalai-docs and docs.relational.ai/deployment.json updates.

[github-actions]

The templates docs preview for this pull request has been deployed to Vercel!

✅ Preview:	https://relationalai-docs-3ztokwm18-relationalai.vercel.app/build/templates
🔍 Inspect:	https://vercel.com/relationalai/relationalai-docs/8vybZoU8hSP5mMPvSQM6GYkU2Mvs