diff --git a/cmd/ragflow_server.go b/cmd/ragflow_server.go
index 6fc51720d0..7f08a78d3d 100644
--- a/cmd/ragflow_server.go
+++ b/cmd/ragflow_server.go
@@ -33,8 +33,8 @@ import (
 	"ragflow/internal/agent/runtime"
 	agenttool "ragflow/internal/agent/tool"
 	"ragflow/internal/channels"
-	native "ragflow/internal/deepdoc/native"
-	pdf "ragflow/internal/deepdoc/parser/pdf"
+	"ragflow/internal/deepdoc/native"
+	"ragflow/internal/deepdoc/parser/pdf"
 	modelModule "ragflow/internal/entity/models"
 	"ragflow/internal/handler"
 	"ragflow/internal/ingestion/knowledge_compile"
@@ -44,7 +44,7 @@ import (
 	"ragflow/internal/server/local"
 	"ragflow/internal/service"
 	"ragflow/internal/service/chunk"
-	dataset "ragflow/internal/service/dataset"
+	"ragflow/internal/service/dataset"
 	"ragflow/internal/service/document"
 	"ragflow/internal/service/file"
 	"ragflow/internal/service/nav"
@@ -682,7 +682,7 @@ func runAdmin(ctx context.Context, serverName string, args *serverArgs) error {
 	ginEngine := gin.New()
 	// Mirror Quart's merge_slashes: collapse duplicate slashes before routing.
 	ginEngine.RemoveExtraSlash = true
-	// Only honour X-Forwarded-For / X-Real-IP from the configured proxies
+	// Only honor X-Forwarded-For / X-Real-IP from the configured proxies
 	// (default: the loopback nginx bundled in the image), never from every peer.
 	if err := common.ConfigureTrustedProxies(ginEngine, globalConfig.GetAPIServerConfig().TrustedProxies); err != nil {
 		common.Fatal("Failed to configure trusted proxies", zap.Error(err))
@@ -1205,7 +1205,7 @@ func startServer(ctx context.Context, serverName string, arguments *serverArgs)
 	ginEngine := gin.New()
 	// Mirror Quart's merge_slashes: collapse duplicate slashes before routing.
 	ginEngine.RemoveExtraSlash = true
-	// Only honour X-Forwarded-For / X-Real-IP from the configured proxies
+	// Only honor X-Forwarded-For / X-Real-IP from the configured proxies
 	// (default: the loopback nginx bundled in the image), never from every
 	// peer. c.ClientIP() feeds the agent webhook ip_whitelist gate and the
 	// login audit records, so gin's trust-everything default would let any
diff --git a/internal/agent/component/switch.go b/internal/agent/component/switch.go
index 0be3658525..d1d2c1be5c 100644
--- a/internal/agent/component/switch.go
+++ b/internal/agent/component/switch.go
@@ -410,7 +410,7 @@ func evaluateClause(clause map[string]any, state *runtime.CanvasState) (bool, er
 			return ln < rn, nil
 		case ">=":
 			return ln >= rn, nil
-		case "<=":
+		default:
 			return ln <= rn, nil
 		}
 	}
diff --git a/internal/common/retry.go b/internal/common/retry.go
index a4de4be11b..2af4755a15 100644
--- a/internal/common/retry.go
+++ b/internal/common/retry.go
@@ -113,7 +113,7 @@ func IsTransientError(err error) bool {
 		if code >= 500 || code == 429 {
 			return true
 		}
-		if code >= 400 && code < 500 {
+		if code >= 400 {
 			return false
 		}
 	}
diff --git a/internal/deepdoc/native/det_helpers.go b/internal/deepdoc/native/det_helpers.go
index 6318b389a4..8be80e734b 100644
--- a/internal/deepdoc/native/det_helpers.go
+++ b/internal/deepdoc/native/det_helpers.go
@@ -268,16 +268,3 @@ func clipLine(mw, mh, x0, y0, x1, y1 int) (int, int, int, int) {
 	}
 	return x0, y0, x1, y1
 }
-
-func math_min(a, b float64) float64 {
-	if a < b {
-		return a
-	}
-	return b
-}
-func math_max(a, b float64) float64 {
-	if a > b {
-		return a
-	}
-	return b
-}
diff --git a/internal/deepdoc/parser/pdf/table/table_cells.go b/internal/deepdoc/parser/pdf/table/table_cells.go
index 84c00f4ecf..cffdb4acbe 100644
--- a/internal/deepdoc/parser/pdf/table/table_cells.go
+++ b/internal/deepdoc/parser/pdf/table/table_cells.go
@@ -656,7 +656,7 @@ func HeaderSetWithBlockType(rows [][]pdf.TSRCell, boxes []pdf.TextBox) map[int]b
 				if bt == "Nu" {
 					continue // numeric cell in a numeric table: ignored
 				}
-				if colHit[ri][ci] || bt != "Nu" {
+				if colHit[ri][ci] {
 					h++
 				}
 			}
diff --git a/internal/engine/serenedb/search.go b/internal/engine/serenedb/search.go
index d3c57e445e..0f8629c0a0 100644
--- a/internal/engine/serenedb/search.go
+++ b/internal/engine/serenedb/search.go
@@ -107,7 +107,7 @@ func (e *serenedbEngine) Search(ctx context.Context, req *types.SearchRequest) (
 	if scored && len(result.Chunks) > 1 {
 		sortByScore(result.Chunks)
 	}
-	if limit > 0 && len(result.Chunks) > limit {
+	if len(result.Chunks) > limit {
 		result.Chunks = result.Chunks[:limit]
 	}
 	if result.Total == 0 {
diff --git a/internal/harness/graph/managed/managed.go b/internal/harness/graph/managed/managed.go
index fdefd0f5dc..1ace73a1b2 100644
--- a/internal/harness/graph/managed/managed.go
+++ b/internal/harness/graph/managed/managed.go
@@ -662,23 +662,6 @@ func cloneMap(src map[string]any) map[string]any {
 	return clone
 }
 
-// DEFAULT_RUNTIME is the default runtime instance with nil values.
-// Configurable is nil (not an empty map) so that direct mutation via Set
-// panics with nil pointer dereference rather than silently corrupting a
-// shared global. Callers must use Clone() to obtain a safe copy.
-// This corresponds to Python's DEFAULT_RUNTIME in runtime.py
-var DEFAULT_RUNTIME = &Runtime{
-	TaskID:       "",
-	NodeName:     "",
-	Step:         0,
-	Configurable: nil,
-	CheckpointNS: "",
-	Context:      nil,
-	Store:        nil,
-	StreamWriter: nil,
-	Previous:     nil,
-}
-
 // GetTaskID returns the task ID from config.
 func GetTaskID(config map[string]interface{}) string {
 	if config == nil {
diff --git a/internal/harness/graph/pregel/traced_engine.go b/internal/harness/graph/pregel/traced_engine.go
index 8cc68e4381..d45ab95603 100644
--- a/internal/harness/graph/pregel/traced_engine.go
+++ b/internal/harness/graph/pregel/traced_engine.go
@@ -225,10 +225,8 @@ func (te *TracedEngine) traceEvent(ctx context.Context, event any, rootSpan trac
 		intSpan.SetStatus(codes.Ok, "")
 		intSpan.End()
 	case EventTypeError:
-		if rootSpan != nil {
-			rootSpan.SetStatus(codes.Error, fmt.Sprintf("%v", se.Error))
-			rootSpan.RecordError(se.Error)
-		}
+		rootSpan.SetStatus(codes.Error, fmt.Sprintf("%v", se.Error))
+		rootSpan.RecordError(se.Error)
 	case EventTypeTaskStart:
 		_, taskSpan := te.tracer.Start(ctx, SpanNodeExecute,
 			trace.WithSpanKind(trace.SpanKindInternal),
diff --git a/internal/ingestion/task/constants.go b/internal/ingestion/task/constants.go
deleted file mode 100644
index d7eebaa8b5..0000000000
--- a/internal/ingestion/task/constants.go
+++ /dev/null
@@ -1,23 +0,0 @@
-//
-//  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
-//
-//  Licensed under the Apache License, Version 2.0 (the "License");
-//  you may not use this file except in compliance with the License.
-//  You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-//  Unless required by applicable law or agreed to in writing, software
-//  distributed under the License is distributed on an "AS IS" BASIS,
-//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-//  See the License for the specific language governing permissions and
-//  limitations under the License.
-//
-
-package task
-
-// Special doc_id values used in task messages (mirrors Python constants).
-const (
-	// GRAPH_RAPTOR_FAKE_DOC_ID is the fake doc_id used for RAPTOR-generated chunks.
-	GRAPH_RAPTOR_FAKE_DOC_ID = "graph_raptor_fake_doc"
-)
diff --git a/internal/ingestion/task/golden_compare.go b/internal/ingestion/task/golden_compare.go
index d5f94b89e1..437e039f7a 100644
--- a/internal/ingestion/task/golden_compare.go
+++ b/internal/ingestion/task/golden_compare.go
@@ -19,7 +19,7 @@ package task
 import (
 	"time"
 
-	indexdoc "ragflow/internal/ingestion/task/indexdoc"
+	"ragflow/internal/ingestion/task/indexdoc"
 )
 
 // GoldenCompareResult is the structured output used by the local golden tools.
diff --git a/internal/rag/agentic-rag/runtime/action_session.go b/internal/rag/agentic-rag/runtime/action_session.go
index fee5baf7bb..5819e9c442 100644
--- a/internal/rag/agentic-rag/runtime/action_session.go
+++ b/internal/rag/agentic-rag/runtime/action_session.go
@@ -1675,11 +1675,9 @@ func (m *InvokerSessionModel) CompleteWithTemperature(ctx context.Context, messa
 		return nil, err
 	}
 	reply := &ModelReply{Content: resp.Content}
-	if resp != nil {
-		reply.Usage = resp.Usage
-		reply.Tokens = totalOf(resp)
-		reply.ToolCalls = nativeToHarnessCalls(resp.ToolCalls)
-	}
+	reply.Usage = resp.Usage
+	reply.Tokens = totalOf(resp)
+	reply.ToolCalls = nativeToHarnessCalls(resp.ToolCalls)
 	return reply, nil
 }
 
@@ -1724,11 +1722,9 @@ func (m *InvokerSessionModel) Complete(ctx context.Context, messages []schema.Me
 		return nil, err
 	}
 	reply := &ModelReply{Content: resp.Content}
-	if resp != nil {
-		reply.Usage = resp.Usage
-		reply.Tokens = totalOf(resp)
-		reply.ToolCalls = nativeToHarnessCalls(resp.ToolCalls)
-	}
+	reply.Usage = resp.Usage
+	reply.Tokens = totalOf(resp)
+	reply.ToolCalls = nativeToHarnessCalls(resp.ToolCalls)
 	return reply, nil
 }
 
diff --git a/internal/service/connector_box_oauth_test.go b/internal/service/connector_box_oauth_test.go
index 139c73af8a..e4f6fec10e 100644
--- a/internal/service/connector_box_oauth_test.go
+++ b/internal/service/connector_box_oauth_test.go
@@ -8,7 +8,7 @@ import (
 	"testing"
 
 	"ragflow/internal/common"
-	kvrocks "ragflow/internal/engine/kvrocks"
+	"ragflow/internal/engine/kvrocks"
 )
 
 type roundTripFunc func(*http.Request) (*http.Response, error)
diff --git a/internal/service/document/knowledge_compile_status.go b/internal/service/document/knowledge_compile_status.go
index cda55970ec..0683d78484 100644
--- a/internal/service/document/knowledge_compile_status.go
+++ b/internal/service/document/knowledge_compile_status.go
@@ -24,7 +24,7 @@ import (
 	"ragflow/internal/common"
 	"ragflow/internal/engine/types"
 	kccommon "ragflow/internal/ingestion/component/knowledge_compiler/common"
-	knowledge_compile "ragflow/internal/ingestion/knowledge_compile"
+	"ragflow/internal/ingestion/knowledge_compile"
 
 	"go.uber.org/zap"
 )
diff --git a/internal/service/ingestion_task_service.go b/internal/service/ingestion_task_service.go
index a4483561f1..f16648cb77 100644
--- a/internal/service/ingestion_task_service.go
+++ b/internal/service/ingestion_task_service.go
@@ -9,7 +9,7 @@ import (
 
 	"ragflow/internal/common"
 	"ragflow/internal/dao"
-	kvrocks "ragflow/internal/engine/kvrocks"
+	"ragflow/internal/engine/kvrocks"
 	"ragflow/internal/entity"
 
 	"go.uber.org/zap"
diff --git a/internal/service/memory.go b/internal/service/memory.go
index cd097fe819..521727be35 100644
--- a/internal/service/memory.go
+++ b/internal/service/memory.go
@@ -21,6 +21,11 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"ragflow/internal/common"
+	"ragflow/internal/entity"
+	"ragflow/internal/entity/models"
+	"ragflow/internal/utility"
+
 	"slices"
 	"sort"
 	"strconv"
@@ -30,14 +35,10 @@ import (
 	"go.uber.org/zap"
 	"gorm.io/gorm"
 
-	"ragflow/internal/common"
 	"ragflow/internal/dao"
 	"ragflow/internal/engine"
 	enginetypes "ragflow/internal/engine/types"
-	"ragflow/internal/entity"
-	models "ragflow/internal/entity/models"
 	"ragflow/internal/service/nlp"
-	"ragflow/internal/utility"
 )
 
 const (
diff --git a/internal/service/memory_extractor.go b/internal/service/memory_extractor.go
index 1c2d7a55a5..6f5c328b0d 100644
--- a/internal/service/memory_extractor.go
+++ b/internal/service/memory_extractor.go
@@ -46,7 +46,7 @@ import (
 	"ragflow/internal/common"
 	"ragflow/internal/dao"
 	"ragflow/internal/entity"
-	models "ragflow/internal/entity/models"
+	"ragflow/internal/entity/models"
 
 	"go.uber.org/zap"
 	"gorm.io/gorm"
diff --git a/internal/service/memory_message_service.go b/internal/service/memory_message_service.go
index a1f2463253..51c8637895 100644
--- a/internal/service/memory_message_service.go
+++ b/internal/service/memory_message_service.go
@@ -61,9 +61,9 @@ import (
 
 	"ragflow/internal/common"
 	"ragflow/internal/dao"
-	kvrocks "ragflow/internal/engine/kvrocks"
+	"ragflow/internal/engine/kvrocks"
 	"ragflow/internal/entity"
-	models "ragflow/internal/entity/models"
+	"ragflow/internal/entity/models"
 	"ragflow/internal/utility"
 
 	"gorm.io/gorm"
diff --git a/internal/syncer/connector/rest_api.go b/internal/syncer/connector/rest_api.go
index b1d364f4ca..ba13175bcc 100644
--- a/internal/syncer/connector/rest_api.go
+++ b/internal/syncer/connector/rest_api.go
@@ -1669,11 +1669,7 @@ func restAPIQuoteString(s string) string {
 			b.WriteString(`\f`)
 		default:
 			if r < 0x20 || r == 0x7f {
-				if r < 0x100 {
-					b.WriteString(fmt.Sprintf(`\x%02x`, r))
-				} else {
-					b.WriteString(fmt.Sprintf(`\u%04x`, r))
-				}
+				b.WriteString(fmt.Sprintf(`\x%02x`, r))
 			} else {
 				b.WriteRune(r)
 			}
diff --git a/internal/tokenizer/spm.go b/internal/tokenizer/spm.go
index ca712052b9..03540bcfc5 100644
--- a/internal/tokenizer/spm.go
+++ b/internal/tokenizer/spm.go
@@ -315,11 +315,11 @@ func (m *sentencePieceModel) parseNormalizerSpec(raw []byte) error {
 				m.addDummyPrefix = on
 			case 4:
 				m.removeExtraWhitespaces = on
-			case 5:
+			default:
 				m.escapeWhitespaces = on
 			}
 		default:
-			if err := r.skip(wire); err != nil {
+			if err = r.skip(wire); err != nil {
 				return fmt.Errorf("sentencepiece: normalizer_spec: %w", err)
 			}
 		}