⚡ Bolt: [performance improvement] Reuse http.Client in usage API calls

.jules/bolt.md

@@ -21,3 +21,7 @@
 ## 2025-05-10 - fmt.Sscanf is lenient, strconv.Atoi is strict
 **Learning:** In Go, `fmt.Sscanf("%d")` parses digits until it encounters a non-digit character (e.g., `"2beta"` parses as `2`), while `strconv.Atoi` fails and returns `0` for the entire string. If you need the lenient parsing behavior of `fmt.Sscanf` for performance optimization, implement a custom byte-traversal loop to extract leading digits rather than relying on `strconv.Atoi` or regex, as it is over 10x faster and maintains exact functional parity.
 **Action:** When replacing `fmt.Sscanf` for performance, always evaluate whether the leniency of the parser is being implicitly relied upon by the surrounding code.
+
+## 2025-05-11 - Reuse http.Client to avoid TLS handshake overhead
+**Learning:** Recreating an `http.Client` for every request is a performance anti-pattern that prevents TCP connection reuse (keep-alive) and forces new TLS handshakes, which is significantly slower for APIs like Anthropic's.
+**Action:** Lift `http.Client` instances to package-level variables or struct fields for reuse to enable connection pooling, as they are explicitly designed to be thread-safe.

internal/plugins/usage_common.go

@@ -37,6 +37,8 @@ const (
 	usageDiskCacheTTL = 5 * time.Minute
 )
 
+var usageClient = &http.Client{Timeout: usageAPITimeout}
+
 // UsageResponse represents the API response from the usage endpoint
 type UsageResponse struct {
 	FiveHour     *UsageLimit `json:"five_hour"`
@@ -181,8 +183,7 @@ func FetchUsage(ctx context.Context, token string) (*UsageResponse, error) {
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("anthropic-beta", "oauth-2025-04-20")
 
-	client := &http.Client{Timeout: usageAPITimeout}
-	resp, err := client.Do(req)
+	resp, err := usageClient.Do(req)
 	if err != nil {
 		return nil, fmt.Errorf("failed to fetch usage: %w", err)
 	}