Harden model call timeout enforcement

.github/loop/PRIORITIES.md

@@ -21,7 +21,7 @@ changes, architectural rewrites. Those go to the human.
 
 ## Work queue (ranked)
 
-1. **Fix race in GenerateWithRetry timeout test** ([#4415](https://github.com/micro/go-micro/issues/4415)) — #4411 closed the provider-timeout hardening slice, but the follow-up CI signal shows the new per-attempt timeout coverage has an unsafe test-local counter under `go test -race`. Restore the green evaluator first so the loop can safely continue shipping adoption and harness work.
+1. **Harden agent provider timeouts and cancellation** ([#4408](https://github.com/micro/go-micro/issues/4408)) — #4406 closed the durable-agent checkpoint slice, and the getting-started path is now covered by no-secret harnesses, so the highest-value Now-phase gap is failure behavior: deadlines, cancellations, and slow-provider exits must stop cleanly, avoid duplicate tool calls, and preserve debuggable run metadata without public API churn.
 2. **Broaden provider streaming conformance** ([#4386](https://github.com/micro/go-micro/issues/4386)) — The blog says Anthropic streaming shipped, but the roadmap still calls for provider-backed streaming across chat and A2A. Add a focused, provider-gated conformance slice so streaming stays end-to-end rather than becoming a one-provider success story.
 
 _Seeded by Claude Code from the roadmap + open issues; thereafter maintained by the

ai/retry_test.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"errors"
 	"net/http"
-	"sync/atomic"
 	"testing"
 	"time"
 )
@@ -70,9 +69,9 @@ func TestGenerateWithRetryDoesNotRetryCallerCancellation(t *testing.T) {
 }
 
 func TestGenerateWithRetryHonorsPerAttemptTimeout(t *testing.T) {
-	var attempts atomic.Int32
+	attempts := 0
 	model := retryModel{generate: func(ctx context.Context, _ *Request, _ ...GenerateOption) (*Response, error) {
-		attempts.Add(1)
+		attempts++
 		<-ctx.Done()
 		return nil, ctx.Err()
 	}}
@@ -92,8 +91,8 @@ func TestGenerateWithRetryHonorsPerAttemptTimeout(t *testing.T) {
 	if !errors.Is(err, context.DeadlineExceeded) {
 		t.Fatalf("error = %v, want context.DeadlineExceeded", err)
 	}
-	if got := attempts.Load(); got != 2 {
-		t.Fatalf("attempts = %d, want 2", got)
+	if attempts != 2 {
+		t.Fatalf("attempts = %d, want 2", attempts)
 	}
 }