fix(auth): send explicit User-Agent from ResendClient so Cloudflare stops blocking magic-link emails#239
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api.resend.com sits behind Cloudflare, which blocks urllib's default
`Python-urllib/x.y` User-Agent with HTTP 403 ("error code: 1010")
before the request reaches Resend's API. Every magic-link sign-in
email was silently dropped in production as a result: Resend logged
zero send attempts and the API key showed zero uses, while wot-api
logged a bare `resend_send_exception: HTTP Error 403: Forbidden`.
Proven by two identical curl calls to api.resend.com differing only
in the User-Agent string: `Python-urllib/3.11` -> 403 "error code:
1010"; a normal UA -> 200 with a message id.
Changes:
- ResendClient sends an explicit `User-Agent: WorldOfTaxonomy/1.0`.
- HTTP 4xx/5xx is now caught as urllib.error.HTTPError and logged
with the response body, so an edge block ("error code: 1010") is
distinguishable from an API error (bad key / unverified domain).
- Adds TestResendClient: payload, User-Agent, and error-handling
regression coverage.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Magic-link sign-in emails have been silently dropped in production since the developer-auth feature shipped. The cause is not the email account, the API key, or DNS — it is the HTTP
User-Agent.api.resend.comsits behind Cloudflare.ResendClient.send()calls it with Python'surllib, which sends the defaultUser-Agent: Python-urllib/3.x. Cloudflare bot protection blocks that signature with HTTP 403 / "error code: 1010" before the request ever reaches Resend's API.Symptom
POST /api/v1/developers/signupreturns202and the UI shows "Check your inbox" (the endpoint deliberately never 500s on an email failure).resend_send_exception: HTTP Error 403: Forbidden— with no response body, so the real cause was invisible.Root cause — proven
Two identical
curlcalls toapi.resend.com/emails— same key, same IP, same TLS — differing only in theUser-Agent:Python-urllib/3.11HTTP 403—error code: 1010HTTP 200—{"id":"..."}(email delivered)The
200call delivered a real email to the account inbox, confirming the API key, the verifiedaixcelerator.aidomain, and thenoreply@aixcelerator.aisender all work. The block is entirelyUser-Agent-string based.Changes
world_of_taxonomy/auth/email.py—ResendClient:User-Agent: WorldOfTaxonomy/1.0header.urllib.error.HTTPErrorand logged with the response body (resend_send_failed: status=... body=...). The previous code logged a bareHTTP Error 403, hiding whether the cause was the API (bad key / unverified domain) or the Cloudflare edge. The oldif response.status >= 400branch was also dead code —urllibraisesHTTPErrorfor 4xx/5xx, it never returns them.tests/test_magic_link.py:TestResendClient— covers the request payload, theUser-Agentheader (regression guard: asserts it is set and is notpython-urllib), and the swallow-and-log behaviour on HTTP errors.Testing
TestResendClient(3 tests) — verified via a mockedurlopen, no network or key needed.curlsend with a normalUser-Agentdelivered to inbox — DKIM + SPF pass and align, clearing theaixcelerator.aip=rejectDMARC policy.Deployment context (already provisioned — no action in this PR)
On the
wot-apiCloud Run service:RESEND_API_KEY— GCP Secret ManagerRESEND_SENDER=noreply@aixcelerator.aiaixcelerator.aiverified in Resend (DKIM + SPF DNS records)Merging to
maintriggerswot-main-autodeploy, which builds and deploys wot-api. After deploy, a sign-in request on https://www.worldoftaxonomy.com/login should deliver the magic link.Risk
Low. Two-file change scoped to
ResendClient: one added request header plus improved error logging. No change to the sign-in flow, token handling, or any other code path.🤖 Generated with Claude Code