feat: expose rate limit headers via on_rate_limit_info callback#41
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Surface x-ratelimit-* headers from successful responses so callers can build observability around the rate limit (warn at thresholds, emit metrics) without inspecting internals. - Extend RateLimitInfo with method, url, and usage_pct() helper - Add RateLimitInfoCallback type alias (Arc<dyn Fn + Send + Sync>) - Add on_rate_limit_info option on Config and ConfigBuilder - Parse and emit headers on every successful response in make_request - Ship logging_rate_limit_observer as a zero-config observer (defaults: 80/90/95%) - Callback panics are caught with std::panic::catch_unwind so they cannot break requests - Fix pre-existing clippy collapsible_if warnings in invoice and credit_note examples - Backward-compatible: option is optional, default behavior unchanged
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May 11, 2026
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Adds an optional
on_rate_limit_infocallback onConfigso callers can readx-ratelimit-*headers from successful responses. Today the SDK drops them on 2xx, which makes 80/90/95% threshold observability impossible without inspecting internals. The 429 path is unchanged. Mirrors PRs getlago/lago-python-client#393, getlago/lago-go-client#336, getlago/lago-ruby-client#347, and getlago/lago-javascript-client#86.Notes for review
Option<Arc<dyn Fn(&RateLimitInfo) + Send + Sync>>so the client staysCloneandSend + Sync.std::panic::catch_unwindand logged so a buggy observer can't break a request.RateLimitInfogainedmethod,urlfields and ausage_pct()helper.Defaultis now derived so existing struct-literal tests use..Default::default().clippy::collapsible_ifwarnings in unrelated examples (invoice.rs,credit_note.rs) were folded in to keep CI green; happy to split out if you'd prefer.Tests
5 new tests in
client.rs(usage_pct happy + unusable, success path, missing-headers, panic recovery) plus 3 inobservability.rs. Backward-compatible — all existing tests pass after..Default::default()updates.