[svc-agent]

Hotfix to main: run Vercel functions in fra1 (Frankfurt), next to the Upstash database (eu-central-1). Already on staging (3430f27). After merge, main and staging hold identical files.

Why

Functions ran in Vercel's default iad1 (Washington DC), so every Redis call crossed the Atlantic. Measured on production after #260:

• One Upstash round trip is ~85 ms: /api/auth/session (four Redis calls in a row) has a median of 542 ms; an endpoint without Redis takes 185 ms.
• Redis is on the hot path of every signed-in request: the session cookie lookup, the OAuth request lock (fix(auth): OAuth request lock, and keep sessions through transient restore failures (TECH-807) #260, taken twice per proxied call and serialising one user's parallel requests), the session store and rate limits.
• A burst of 12 parallel signed-in reads of your own records took up to 6.3 s (7.5 s for the burst). The same burst of public reads, which skip the session, took 0.5 s.
• Production responses show x-vercel-id: fra1::iad1::…: requests enter Vercel in Frankfurt, run in Washington DC, and call Redis back in Frankfurt.

Our infrastructure is in Europe; only Bluesky services (plc.directory, the Bluesky AppView and bsky.network PDSes) are in the US, and calls to those get slower from Frankfurt.

Change

• vercel.json: "regions": ["fra1"]. No region was set anywhere before (no vercel.json, no preferredRegion).
• AGENTS.md: the region and why, in §19, and the file map.

Review (three subagents: Vercel config, outbound latency, region-bound side effects)

• Config: regions in vercel.json covers every function, including src/proxy.ts, which runs as a Node lambda in the function region. The deployment API shows regions: ["fra1"] on staging (the previous staging deployment showed iad1). Nothing else about the deployment changed. The project's dashboard default was still iad1; it is now fra1 too, so both agree.
• Upstreams in the EU: certified.one (PDS + OAuth server), the group service and the indexer, so those calls get faster as well. Staging's Upstash database is also in eu-central-1.
• Slower now: calls to US-hosted Bluesky services (plc.directory, public.api.bsky.app, *.host.bsky.network PDSes, Resend). The noticeable case is profile resolution for many Bluesky-hosted identities on a cold cache (/api/resolve-dids, up to about +0.6 to 1.3 s), plus uncached handle lookups in page metadata. Caching is the follow-up; don't give those routes a preferredRegion, because they also use Redis.
• No issues: rate limiting (client IP comes from the edge), allowlists, OAuth/DPoP, CSP and caches (the per-region data cache warms up once). The privacy policy already says "primarily within the European Union".

Testing

• Staging: x-vercel-id: fra1::fra1::… on /api/auth/session. Pages, public xrpc reads and the well-known endpoints all answer normally.
• After merge: repeat the production measurement signed in. Redis calls should drop to a few ms and the 12-read burst to about a second.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation
  • Updated deployment guidance to explain how regional hosting is configured and how services stay aligned with their data infrastructure.
  • No changes to app features or user-facing behavior.

Confidence Score: 5/5

This PR appears safe to merge.

Summary

Sets Vercel functions to fra1 and documents why they should stay near Redis.

• Vercel functions now run in Frankfurt near Redis.

_{Reviews (1) · Last reviewed commit: "docs(agents): record the dashboard regio..." · Reviewed by Greptile}

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
certified-app	Ready	Preview	Oct 29, 2026 2:01pm UTC

[coderabbitai]

No actionable comments were generated in the recent review.

Recent review info

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Commits

Reviewing files that changed from the base of the PR and between 17b3a70 and 70d2656.

Files selected for processing: 2

• AGENTS.md
• vercel.json

Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review.

Walkthrough

The Vercel configuration sets the function region to fra1. AGENTS.md documents this setting and advises keeping Redis-backed services in eu-central-1.

Changes: Function region configuration

Layer / File(s)	Summary
Configure and document the function region vercel.json, AGENTS.md	vercel.json sets the function region to fra1. AGENTS.md documents the region, Redis placement, and the preferredRegion guidance.

Priority: Normal

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Other

Suggested reviewers: holkeb

Merge Risk: Minimal · up to 70d26

No actionable merge-blocking risk was found in this configuration-only change.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: configuring Vercel functions to run in fra1 near Upstash.
Docstring Coverage		No eligible functions found in the changed files. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentat…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No eligible functions found in the changed files. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 0 functions across 0 files. (2 skipped: 2 unsupported.)

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