Introduces internal/requestid package with shared context key to avoid
circular imports between server and middleware packages. Server's
RequestID middleware now uses the shared key. Client middleware picks up
the ID from context and sets X-Request-Id on outgoing requests.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Deduplicate sentinel errors: httpx.ErrNoHealthy, ErrCircuitOpen, and
ErrRetryExhausted are now aliases to the canonical sub-package values
so errors.Is works across package boundaries
- Retry transport returns ErrRetryExhausted only when all attempts are
actually exhausted, not on early policy exit
- Balancer: pre-parse endpoint URLs at construction, replace req.Clone
with cheap shallow struct copy to avoid per-request allocations
- Circuit breaker: Load before LoadOrStore to avoid allocating a Breaker
on every request for known hosts
- Health checker: drain response body before close for connection reuse,
probe endpoints concurrently, run initial probe synchronously in Start
- Client: add Close() to shut down health checker goroutine, propagate
URL resolution errors instead of silently discarding them
- MockClock: fix lock ordering in Reset (clock.mu before t.mu), fix
timer slice compaction to avoid backing-array aliasing, extract
fireExpired to deduplicate Advance/Set
Introduce the core building blocks for the httpx library:
- middleware.Middleware type and Chain() composer
- Error struct with sentinel errors (ErrRetryExhausted, ErrCircuitOpen, ErrNoHealthy)
- internal/clock package with Clock interface and MockClock for deterministic testing
