chore: lint fixes part 10 (#262)

- nilnil (4 → 0): added nolint:nilnil to intentional nil, nil returns in test mocks (MockProvider.CreateInterceptor, mockServerProxier.CallTool) and lastUserPrompt (no user prompt found is not an error)
- gocritic FullResponseWriter (1 → 0): added Hijack() method to statusCapturingWriter delegating to underlying http.Hijacker
- revive defer-in-loop (1 → 0): replaced defer shutdownCancel() with explicit shutdownCancel() call after events.Shutdown
- staticcheck SA1026 (1 → 0): replaced responses.Error (which embeds *http.Request with unmarshalable GetBody func) with a plain struct matching the same JSON shape

All lint errors are now resolved — 0 remaining.

Author: pawbana

circuitbreaker/circuitbreaker.go

@@ -1,8 +1,10 @@
 package circuitbreaker
 
 import (
+	"bufio"
 	"errors"
 	"fmt"
+	"net"
 	"net/http"
 	"sync"
 	"time"
@@ -101,7 +103,8 @@ func (p *ProviderCircuitBreakers) Get(endpoint, model string) *gobreaker.Circuit
 }
 
 // statusCapturingWriter wraps http.ResponseWriter to capture the status code.
-// It also implements http.Flusher to support streaming responses.
+// It implements http.Flusher to support streaming and http.Hijacker to
+// satisfy the FullResponseWriter lint rule.
 type statusCapturingWriter struct {
 	http.ResponseWriter
 	statusCode    int
@@ -130,6 +133,14 @@ func (w *statusCapturingWriter) Flush() {
 	}
 }
 
+func (w *statusCapturingWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	h, ok := w.ResponseWriter.(http.Hijacker)
+	if !ok {
+		return nil, nil, xerrors.New("upstream ResponseWriter does not support hijacking")
+	}
+	return h.Hijack()
+}
+
 // Unwrap returns the underlying ResponseWriter for interface checks.
 func (w *statusCapturingWriter) Unwrap() http.ResponseWriter {
 	return w.ResponseWriter

intercept/chatcompletions/paramswrap.go

@@ -52,7 +52,7 @@ func (c *ChatCompletionNewParamsWrapper) lastUserPrompt() (*string, error) {
 	// We only care if the last message was issued by a user.
 	msg := c.Messages[len(c.Messages)-1]
 	if msg.OfUser == nil {
-		return nil, nil
+		return nil, nil //nolint:nilnil // no user prompt found is not an error
 	}
 
 	if msg.OfUser.Content.OfString.String() != "" {
@@ -69,5 +69,5 @@ func (c *ChatCompletionNewParamsWrapper) lastUserPrompt() (*string, error) {
 		}
 	}
 
-	return nil, nil
+	return nil, nil //nolint:nilnil // no text content found is not an error
 }

intercept/messages/base_test.go

@@ -812,7 +812,7 @@ func (m *mockServerProxier) GetTool(id string) *mcp.Tool {
 }
 
 func (*mockServerProxier) CallTool(context.Context, string, any) (*mcpgo.CallToolResult, error) {
-	return nil, nil
+	return nil, nil //nolint:nilnil // mock: no-op implementation
 }
 
 func TestFilterBedrockBetaFlags(t *testing.T) {

intercept/messages/streaming.go

@@ -515,11 +515,11 @@ newStream:
 		}
 
 		shutdownCtx, shutdownCancel := context.WithTimeout(ctx, time.Second*30)
-		defer shutdownCancel()
 		// Give the events stream 30 seconds (TODO: configurable) to gracefully shutdown.
 		if err := events.Shutdown(shutdownCtx); err != nil {
 			logger.Warn(ctx, "event stream shutdown", slog.Error(err))
 		}
+		shutdownCancel()
 
 		// Cancel the stream context, we're now done.
 		if interceptionErr != nil {

intercept/responses/base.go

@@ -127,7 +127,13 @@ func (i *responsesInterceptionBase) validateRequest(ctx context.Context, w http.
 // sendCustomErr sends custom responses.Error error to the client
 // it should only be called before any data is sent back to the client
 func (i *responsesInterceptionBase) sendCustomErr(ctx context.Context, w http.ResponseWriter, code int, err error) {
-	respErr := responses.Error{
+	// Same JSON shape as responses.Error but using a plain struct because
+	// responses.Error embeds *http.Request whose GetBody func field
+	// is not JSON-marshalable (SA1026).
+	respErr := struct {
+		Code    string `json:"code"`
+		Message string `json:"message"`
+	}{
 		Code:    strconv.Itoa(code),
 		Message: err.Error(),
 	}

internal/testutil/mockprovider.go

@@ -32,5 +32,5 @@ func (m *MockProvider) CreateInterceptor(w http.ResponseWriter, r *http.Request,
 	if m.InterceptorFunc != nil {
 		return m.InterceptorFunc(w, r, tracer)
 	}
-	return nil, nil
+	return nil, nil //nolint:nilnil // mock: no interceptor configured is not an error
 }