fix: route libcurl debug output through SENTRY_TRACE

[jpnurmi]

Note

This is an opinionated behavior change. Previously, sentry_options_set_debug(options, true) also made libcurl's verbose debug output visible. With this change, that output is routed through the Sentry logger at TRACE level and is therefore no longer shown by default.

Applications that still want the curl/transport diagnostics can opt in:

sentry_options_set_debug(options, true);
sentry_options_set_logger_level(options, SENTRY_LEVEL_TRACE);

Using the existing logger level provides explicit control over this useful but noisy output without introducing curl- or transport-specific configuration flags.

Problem A: Sentry logger cannot capture curl output (#887)

• Install CURLOPT_DEBUGFUNCTION and route curl debug logs through the Sentry logger. As a bonus, this makes curl debug output visible in sentry-daemon logs.

Problem B: curl debug output is overly verbose (#555)

• Use SENTRY_TRACE (instead of SENTRY_DEBUG) to avoid the verbose curl debug output being visible by default when debug logging is enabled.

Before

[sentry] DEBUG shutting down background worker thread
[sentry] DEBUG submitting task to background worker thread
< HTTP/2 200 
< server: nginx
< date: Thu, 09 Jul 2026 15:16:01 GMT
< content-type: application/json
< content-length: 2
< vary: origin, access-control-request-method, access-control-request-headers
< access-control-allow-origin: *
< access-control-expose-headers: x-sentry-error,x-sentry-rate-limits,retry-after
< cross-origin-resource-policy: cross-origin
< strict-transport-security: max-age=31536000; includeSubDomains; preload
< via: 1.1 google
< alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
< 
{}* Connection #0 to host o447951.ingest.us.sentry.io left intact
[sentry] DEBUG executing task on worker thread

After

[sentry] DEBUG shutting down background worker thread
[sentry] DEBUG submitting task to background worker thread
[sentry] TRACE < HTTP/2 200 
[sentry] TRACE < server: nginx
[sentry] TRACE < date: Thu, 09 Jul 2026 15:06:58 GMT
[sentry] TRACE < content-type: application/json
[sentry] TRACE < content-length: 2
[sentry] TRACE < vary: origin, access-control-request-method, access-control-request-headers
[sentry] TRACE < access-control-allow-origin: *
[sentry] TRACE < access-control-expose-headers: x-sentry-error,x-sentry-rate-limits,retry-after
[sentry] TRACE < cross-origin-resource-policy: cross-origin
[sentry] TRACE < strict-transport-security: max-age=31536000; includeSubDomains; preload
[sentry] TRACE < via: 1.1 google
[sentry] TRACE < alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
[sentry] TRACE {}
[sentry] TRACE * Connection #0 to host o447951.ingest.us.sentry.io left intact
[sentry] DEBUG executing task on worker thread

Close: #555
Close: #887

[JoshuaMoelans]

LGTM, also agree with putting these in "TRACE" level. Thanks for the cleanup / consolidation 🧹 !!