fix(sdk-go): improve HTTP client and make jitter thread-safe

client.go

@@ -26,18 +26,18 @@
 type ClientOption func(*Client)
 
 // WithBaseURL sets the daemon base URL (default: http://127.0.0.1:4590).
 func WithBaseURL(u string) ClientOption {
 	return func(c *Client) { c.baseURL = strings.TrimRight(u, "/") }
 }
 
 // WithHTTPClient sets a custom http.Client.
 func WithHTTPClient(hc *http.Client) ClientOption {
 	return func(c *Client) { c.httpClient = hc }
 }
 
 // WithAPIKey sets an API key for authentication. The key is sent as
 // an Authorization: Bearer header on every request.
 func WithAPIKey(key string) ClientOption {
 	return func(c *Client) { c.apiKey = key }
 }
 
@@ -48,8 +48,12 @@
 // retries with exponential backoff on transient failures.
 func New(opts ...ClientOption) *Client {
 	c := &Client{
-		baseURL:    defaultBaseURL,
-		httpClient: &http.Client{Timeout: 30 * time.Second},
+		baseURL: defaultBaseURL,
+		httpClient: &http.Client{
+			Transport: &http.Transport{
+				ResponseHeaderTimeout: 5 * time.Second,
+			},
+		},
 	}
 	for _, opt := range opts {
 		opt(c)
@@ -76,7 +80,7 @@
 }
 
 // ChatStream sends a prompt and streams the response via SSE.
 func (c *Client) ChatStream(ctx context.Context, req ChatRequest) (*StreamReader, error) {
 	body, err := json.Marshal(req)
 	if err != nil {
 		return nil, fmt.Errorf("hawk-sdk: marshal request: %w", err)

retry.go

@@ -3,13 +3,27 @@ package hawksdk
 import (
 	"bytes"
 	"context"
+	cryptorand "crypto/rand"
+	"encoding/binary"
 	"io"
 	"math"
 	"math/rand"
 	"net/http"
+	"sync/atomic"
 	"time"
 )
 
+// jitterSeed provides a per-process random seed for jitter, avoiding the
+// global math/rand state which is not safe for concurrent use in some
+// runtimes and can produce predictable sequences.
+var jitterSeed = atomic.Int64{}
+
+func init() {
+	var buf [8]byte
+	_, _ = cryptorand.Read(buf[:])
+	jitterSeed.Store(int64(binary.LittleEndian.Uint64(buf[:])))
+}
+
 // RetryConfig configures the automatic retry behavior for API requests.
 type RetryConfig struct {
 	// MaxRetries is the maximum number of retry attempts.
@@ -83,7 +97,10 @@ func (cfg *RetryConfig) backoffDuration(attempt int) time.Duration {
 		backoff = float64(cfg.MaxBackoff)
 	}
 	// Full jitter: random value between 0 and calculated backoff.
-	jittered := time.Duration(rand.Float64() * backoff)
+	// Uses a per-process seed to avoid the global math/rand state.
+	seed := jitterSeed.Add(1)
+	rng := rand.New(rand.NewSource(seed))
+	jittered := time.Duration(rng.Float64() * backoff)
 	return jittered
 }