Preserve caller cancellation in HTTP smoke probes

internal/usecase/smoke_reachability.go

@@ -2,6 +2,7 @@ package usecase
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/http"
 	"net/url"
@@ -58,7 +59,7 @@ func (p reachabilityProbe) run(
 		result.reachable = boolPointer(false)
 	}
 	if requestErr != nil {
-		result.failure = generation.ClassifyFailure(fmt.Errorf("%w: %w", llm.ErrTransport, requestErr))
+		result.failure = httpProbeFailure(ctx, requestErr)
 		if !evidence.DispatchInvoked {
 			return result, fmt.Errorf("execute reachability request: %w", requestErr)
 		}
@@ -66,6 +67,15 @@ func (p reachabilityProbe) run(
 	return result, nil
 }
 
+// Failed I/O can lose context error identity. Check the caller at that boundary,
+// without reclassifying a probe that already established its result.
+func httpProbeFailure(ctx context.Context, err error) domain.ExecutionFailureKind {
+	if contextErr := ctx.Err(); contextErr != nil {
+		return generation.ClassifyFailure(contextErr)
+	}
+	return generation.ClassifyFailure(errors.Join(llm.ErrTransport, err))
+}
+
 func endpointWithoutUserInfo(endpoint string) (string, error) {
 	parsed, err := url.Parse(endpoint)
 	if err != nil {