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Fix Resend requests being blocked by Cloudflare (missing User-Agent) - #19
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_post_to_resend() sent no User-Agent header, so it fell through to Python's default "Python-urllib/x.y" signature -- Resend's Cloudflare WAF blocks that outright (HTTP 403, Cloudflare error 1010) before the request ever reaches Resend's own API. Found during a controlled real -send verification against Resend's sandbox sender (onboarding@resend.dev -> yajats@gmail.com, using a disposable local SQLite database, never production Neon): the request was rejected by Cloudflare, not Resend, until a normal User-Agent was added, after which Resend accepted it (200) and the local delivery row correctly recorded SENT. Also captures the HTTPError response body (previously only status/reason) so a future failure like the "domain not verified" 403 encountered during this same verification is diagnosable from the stored error message alone, without needing to reproduce it manually. send_weekly_summary() in app.py and _send_via_resend() in services/pin_recovery_service.py have the same missing-User-Agent gap and are very likely affected the same way in production -- deliberately left untouched here, out of scope for this fix. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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_post_to_resend() sent no User-Agent header, so it fell through to Python's default "Python-urllib/x.y" signature -- Resend's Cloudflare WAF blocks that outright (HTTP 403, Cloudflare error 1010) before the request ever reaches Resend's own API. Found during a controlled real -send verification against Resend's sandbox sender (onboarding@resend.dev -> yajats@gmail.com, using a disposable local SQLite database, never production Neon): the request was rejected by Cloudflare, not Resend, until a normal User-Agent was added, after which Resend accepted it (200) and the local delivery row correctly recorded SENT.
Also captures the HTTPError response body (previously only status/reason) so a future failure like the "domain not verified" 403 encountered during this same verification is diagnosable from the stored error message alone, without needing to reproduce it manually.
send_weekly_summary() in app.py and _send_via_resend() in services/pin_recovery_service.py have the same missing-User-Agent gap and are very likely affected the same way in production -- deliberately left untouched here, out of scope for this fix.