fix(pluginhost): detach context and log rpc failures in usage handling

- Detach cancellation from context before dispatching usage records to plugins.
- Log debug messages when RPC `usage.handle` calls fail.

Closes: #5244

internal/pluginhost/adapters_test.go

@@ -2283,6 +2283,49 @@ func TestUsageAdapterPreservesExplicitGenerateFalse(t *testing.T) {
 	}
 }
 
+func TestUsageAdapterDetachesContext(t *testing.T) {
+	var receivedCtx context.Context
+	plugin := usagePluginFunc(func(ctx context.Context, record pluginapi.UsageRecord) {
+		receivedCtx = ctx
+	})
+	host := newHostWithRecords(capabilityRecord{
+		id: "usage-detach",
+		plugin: pluginapi.Plugin{Capabilities: pluginapi.Capabilities{
+			UsagePlugin: plugin,
+		}},
+	})
+	adapter := &usageAdapter{
+		host:     host,
+		pluginID: "usage-detach",
+	}
+
+	canceledCtx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	adapter.HandleUsage(canceledCtx, coreusage.Record{
+		Provider: "provider",
+		Model:    "gpt-5.4",
+	})
+	if receivedCtx == nil {
+		t.Fatal("plugin did not receive context")
+	}
+	if errCtx := receivedCtx.Err(); errCtx != nil {
+		t.Fatalf("expected detached context without error, got ctx.Err() = %v", errCtx)
+	}
+
+	receivedCtx = nil
+	adapter.HandleUsage(nil, coreusage.Record{
+		Provider: "provider",
+		Model:    "gpt-5.4",
+	})
+	if receivedCtx == nil {
+		t.Fatal("plugin did not receive context for nil input")
+	}
+	if errCtx := receivedCtx.Err(); errCtx != nil {
+		t.Fatalf("expected non-nil context without error for nil input, got ctx.Err() = %v", errCtx)
+	}
+}
+
 func TestUsageManagerRegisterNamedReplacesWithoutDuplicateDispatch(t *testing.T) {
 	manager := coreusage.NewManager(0)
 	defer manager.Stop()

internal/pluginhost/adapters_usage_translation.go

@@ -136,6 +136,11 @@ func (a *usageAdapter) HandleUsage(ctx context.Context, record coreusage.Record)
 	if plugin == nil {
 		return
 	}
+	if ctx == nil {
+		ctx = context.Background()
+	} else {
+		ctx = context.WithoutCancel(ctx)
+	}
 	defer func() {
 		if recovered := recover(); recovered != nil {
 			a.host.fusePlugin(a.pluginID, "UsagePlugin.HandleUsage", recovered)

internal/pluginhost/rpc_client.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/router-for-me/CLIProxyAPI/v7/sdk/pluginabi"
 	"github.com/router-for-me/CLIProxyAPI/v7/sdk/pluginapi"
+	log "github.com/sirupsen/logrus"
 )
 
 type rpcPluginAdapter struct {
@@ -539,7 +540,9 @@ func (a rpcThinkingApplier) ApplyThinking(ctx context.Context, req pluginapi.Thi
 }
 
 func (a *rpcPluginAdapter) HandleUsage(ctx context.Context, record pluginapi.UsageRecord) {
-	_, _ = callPlugin[rpcEmptyResponse](ctx, a.client, pluginabi.MethodUsageHandle, record)
+	if _, errCall := callPlugin[rpcEmptyResponse](ctx, a.client, pluginabi.MethodUsageHandle, record); errCall != nil {
+		log.Debugf("pluginhost: usage.handle to %s failed: %v", a.id, errCall)
+	}
 }
 
 func (a *rpcPluginAdapter) RegisterCommandLine(ctx context.Context, req pluginapi.CommandLineRegistrationRequest) (pluginapi.CommandLineRegistrationResponse, error) {