diff --git a/plugin/markdown/extensions/tag.go b/plugin/markdown/extensions/tag.go
index 572f1ce31..9b04955ed 100644
--- a/plugin/markdown/extensions/tag.go
+++ b/plugin/markdown/extensions/tag.go
@@ -10,7 +10,7 @@ import (
 
 type tagExtension struct{}
 
-// TagExtension is a goldmark extension for #tag syntax
+// TagExtension is a goldmark extension for #tag syntax.
 var TagExtension = &tagExtension{}
 
 // Extend extends the goldmark parser with tag support.
diff --git a/plugin/markdown/extensions/wikilink.go b/plugin/markdown/extensions/wikilink.go
index 8d7bb046c..a68e8e6ca 100644
--- a/plugin/markdown/extensions/wikilink.go
+++ b/plugin/markdown/extensions/wikilink.go
@@ -10,7 +10,7 @@ import (
 
 type wikilinkExtension struct{}
 
-// WikilinkExtension is a goldmark extension for [[...]] wikilink syntax
+// WikilinkExtension is a goldmark extension for [[...]] wikilink syntax.
 var WikilinkExtension = &wikilinkExtension{}
 
 // Extend extends the goldmark parser with wikilink support.
diff --git a/plugin/markdown/markdown.go b/plugin/markdown/markdown.go
index ab4f95c36..1ee630fb8 100644
--- a/plugin/markdown/markdown.go
+++ b/plugin/markdown/markdown.go
@@ -17,7 +17,7 @@ import (
 	storepb "github.com/usememos/memos/proto/gen/store"
 )
 
-// ExtractedData contains all metadata extracted from markdown in a single pass
+// ExtractedData contains all metadata extracted from markdown in a single pass.
 type ExtractedData struct {
 	Tags       []string
 	Property   *storepb.MemoPayload_Property
@@ -57,12 +57,12 @@ type Service interface {
 	RenameTag(content []byte, oldTag, newTag string) (string, error)
 }
 
-// service implements the Service interface
+// service implements the Service interface.
 type service struct {
 	md goldmark.Markdown
 }
 
-// Option configures the markdown service
+// Option configures the markdown service.
 type Option func(*config)
 
 type config struct {
@@ -70,21 +70,21 @@ type config struct {
 	enableWikilink bool
 }
 
-// WithTagExtension enables #tag parsing
+// WithTagExtension enables #tag parsing.
 func WithTagExtension() Option {
 	return func(c *config) {
 		c.enableTags = true
 	}
 }
 
-// WithWikilinkExtension enables [[wikilink]] parsing
+// WithWikilinkExtension enables [[wikilink]] parsing.
 func WithWikilinkExtension() Option {
 	return func(c *config) {
 		c.enableWikilink = true
 	}
 }
 
-// NewService creates a new markdown service with the given options
+// NewService creates a new markdown service with the given options.
 func NewService(opts ...Option) Service {
 	cfg := &config{}
 	for _, opt := range opts {
@@ -115,14 +115,14 @@ func NewService(opts ...Option) Service {
 	}
 }
 
-// parse is an internal helper to parse content into AST
+// parse is an internal helper to parse content into AST.
 func (s *service) parse(content []byte) (gast.Node, error) {
 	reader := text.NewReader(content)
 	doc := s.md.Parser().Parse(reader)
 	return doc, nil
 }
 
-// ExtractTags returns all #tags found in content
+// ExtractTags returns all #tags found in content.
 func (s *service) ExtractTags(content []byte) ([]string, error) {
 	root, err := s.parse(content)
 	if err != nil {
@@ -153,7 +153,7 @@ func (s *service) ExtractTags(content []byte) ([]string, error) {
 	return uniqueLowercase(tags), nil
 }
 
-// ExtractProperties computes boolean properties about the content
+// ExtractProperties computes boolean properties about the content.
 func (s *service) ExtractProperties(content []byte) (*storepb.MemoPayload_Property, error) {
 	root, err := s.parse(content)
 	if err != nil {
@@ -171,15 +171,9 @@ func (s *service) ExtractProperties(content []byte) (*storepb.MemoPayload_Proper
 		case gast.KindLink, mast.KindWikilink:
 			prop.HasLink = true
 
-		case mast.KindWikilink:
-			prop.HasLink = true
-
 		case gast.KindCodeBlock, gast.KindFencedCodeBlock, gast.KindCodeSpan:
 			prop.HasCode = true
 
-		case gast.KindCodeSpan:
-			prop.HasCode = true
-
 		case east.KindTaskCheckBox:
 			prop.HasTaskList = true
 			if checkBox, ok := n.(*east.TaskCheckBox); ok {
@@ -187,6 +181,8 @@ func (s *service) ExtractProperties(content []byte) (*storepb.MemoPayload_Proper
 					prop.HasIncompleteTasks = true
 				}
 			}
+		default:
+			// No special handling for other node types
 		}
 
 		return gast.WalkContinue, nil
@@ -199,7 +195,7 @@ func (s *service) ExtractProperties(content []byte) (*storepb.MemoPayload_Proper
 	return prop, nil
 }
 
-// ExtractReferences returns all wikilink references found in content
+// ExtractReferences returns all wikilink references found in content.
 func (s *service) ExtractReferences(content []byte) ([]string, error) {
 	root, err := s.parse(content)
 	if err != nil {
@@ -229,7 +225,7 @@ func (s *service) ExtractReferences(content []byte) ([]string, error) {
 	return references, nil
 }
 
-// RenderMarkdown renders goldmark AST back to markdown text
+// RenderMarkdown renders goldmark AST back to markdown text.
 func (s *service) RenderMarkdown(content []byte) (string, error) {
 	root, err := s.parse(content)
 	if err != nil {
@@ -240,7 +236,7 @@ func (s *service) RenderMarkdown(content []byte) (string, error) {
 	return mdRenderer.Render(root, content), nil
 }
 
-// RenderHTML renders markdown content to HTML using goldmark's built-in HTML renderer
+// RenderHTML renders markdown content to HTML using goldmark's built-in HTML renderer.
 func (s *service) RenderHTML(content []byte) (string, error) {
 	var buf bytes.Buffer
 	if err := s.md.Convert(content, &buf); err != nil {
@@ -249,7 +245,7 @@ func (s *service) RenderHTML(content []byte) (string, error) {
 	return buf.String(), nil
 }
 
-// GenerateSnippet creates a plain text summary from markdown content
+// GenerateSnippet creates a plain text summary from markdown content.
 func (s *service) GenerateSnippet(content []byte, maxLength int) (string, error) {
 	root, err := s.parse(content)
 	if err != nil {
@@ -265,6 +261,8 @@ func (s *service) GenerateSnippet(content []byte, maxLength int) (string, error)
 			switch n.Kind() {
 			case gast.KindCodeBlock, gast.KindFencedCodeBlock, gast.KindCodeSpan:
 				return gast.WalkSkipChildren, nil
+			default:
+				// Continue walking for other node types
 			}
 
 			// Add space before block elements (except first)
@@ -273,6 +271,8 @@ func (s *service) GenerateSnippet(content []byte, maxLength int) (string, error)
 				if buf.Len() > 0 && lastNodeWasBlock {
 					buf.WriteByte(' ')
 				}
+			default:
+				// No space needed for other node types
 			}
 		}
 
@@ -281,6 +281,8 @@ func (s *service) GenerateSnippet(content []byte, maxLength int) (string, error)
 			switch n.Kind() {
 			case gast.KindParagraph, gast.KindHeading, gast.KindListItem:
 				lastNodeWasBlock = true
+			default:
+				// Not a block element
 			}
 			return gast.WalkContinue, nil
 		}
@@ -321,14 +323,14 @@ func (s *service) GenerateSnippet(content []byte, maxLength int) (string, error)
 	return strings.TrimSpace(snippet), nil
 }
 
-// ValidateContent checks if the markdown content is valid
+// ValidateContent checks if the markdown content is valid.
 func (s *service) ValidateContent(content []byte) error {
 	// Try to parse the content
 	_, err := s.parse(content)
 	return err
 }
 
-// ExtractAll extracts tags, properties, and references in a single parse for efficiency
+// ExtractAll extracts tags, properties, and references in a single parse for efficiency.
 func (s *service) ExtractAll(content []byte) (*ExtractedData, error) {
 	root, err := s.parse(content)
 	if err != nil {
@@ -362,15 +364,9 @@ func (s *service) ExtractAll(content []byte) (*ExtractedData, error) {
 		case gast.KindLink, mast.KindWikilink:
 			data.Property.HasLink = true
 
-		case mast.KindWikilink:
-			data.Property.HasLink = true
-
 		case gast.KindCodeBlock, gast.KindFencedCodeBlock, gast.KindCodeSpan:
 			data.Property.HasCode = true
 
-		case gast.KindCodeSpan:
-			data.Property.HasCode = true
-
 		case east.KindTaskCheckBox:
 			data.Property.HasTaskList = true
 			if checkBox, ok := n.(*east.TaskCheckBox); ok {
@@ -378,6 +374,8 @@ func (s *service) ExtractAll(content []byte) (*ExtractedData, error) {
 					data.Property.HasIncompleteTasks = true
 				}
 			}
+		default:
+			// No special handling for other node types
 		}
 
 		return gast.WalkContinue, nil
@@ -393,7 +391,7 @@ func (s *service) ExtractAll(content []byte) (*ExtractedData, error) {
 	return data, nil
 }
 
-// RenameTag renames all occurrences of oldTag to newTag in content
+// RenameTag renames all occurrences of oldTag to newTag in content.
 func (s *service) RenameTag(content []byte, oldTag, newTag string) (string, error) {
 	root, err := s.parse(content)
 	if err != nil {
@@ -425,7 +423,7 @@ func (s *service) RenameTag(content []byte, oldTag, newTag string) (string, erro
 	return mdRenderer.Render(root, content), nil
 }
 
-// uniqueLowercase returns unique lowercase strings from input
+// uniqueLowercase returns unique lowercase strings from input.
 func uniqueLowercase(strs []string) []string {
 	seen := make(map[string]bool)
 	var result []string
@@ -441,7 +439,7 @@ func uniqueLowercase(strs []string) []string {
 	return result
 }
 
-// truncateAtWord truncates a string at the last word boundary before maxLength
+// truncateAtWord truncates a string at the last word boundary before maxLength.
 func truncateAtWord(s string, maxLength int) string {
 	if len(s) <= maxLength {
 		return s
diff --git a/plugin/markdown/markdown_test.go b/plugin/markdown/markdown_test.go
index 9768d2f2a..6260c7470 100644
--- a/plugin/markdown/markdown_test.go
+++ b/plugin/markdown/markdown_test.go
@@ -446,7 +446,7 @@ func TestTruncateAtWord(t *testing.T) {
 	}
 }
 
-// Benchmark tests
+// Benchmark tests.
 func BenchmarkGenerateSnippet(b *testing.B) {
 	svc := NewService()
 	content := []byte(`# Large Document
diff --git a/plugin/markdown/parser/tag.go b/plugin/markdown/parser/tag.go
index b5f01f492..348e3da11 100644
--- a/plugin/markdown/parser/tag.go
+++ b/plugin/markdown/parser/tag.go
@@ -10,7 +10,7 @@ import (
 
 type tagParser struct{}
 
-// NewTagParser creates a new inline parser for #tag syntax
+// NewTagParser creates a new inline parser for #tag syntax.
 func NewTagParser() parser.InlineParser {
 	return &tagParser{}
 }
@@ -20,8 +20,8 @@ func (*tagParser) Trigger() []byte {
 	return []byte{'#'}
 }
 
-// Parse parses #tag syntax
-func (p *tagParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+// Parse parses #tag syntax.
+func (*tagParser) Parse(_ gast.Node, block text.Reader, _ parser.Context) gast.Node {
 	line, _ := block.PeekLine()
 
 	// Must start with #
diff --git a/plugin/markdown/parser/tag_test.go b/plugin/markdown/parser/tag_test.go
index 5a67f49a6..a08755076 100644
--- a/plugin/markdown/parser/tag_test.go
+++ b/plugin/markdown/parser/tag_test.go
@@ -110,7 +110,8 @@ func TestTagParser(t *testing.T) {
 				require.NotNil(t, node, "Expected tag to be parsed")
 				require.IsType(t, &mast.TagNode{}, node)
 
-				tagNode := node.(*mast.TagNode)
+				tagNode, ok := node.(*mast.TagNode)
+				require.True(t, ok, "Expected node to be *mast.TagNode")
 				assert.Equal(t, tt.expectedTag, string(tagNode.Tag))
 			} else {
 				assert.Nil(t, node, "Expected tag NOT to be parsed")
@@ -137,7 +138,8 @@ func TestTagParser_MultipleTags(t *testing.T) {
 	// Parse first tag
 	node1 := p.Parse(nil, reader, ctx)
 	require.NotNil(t, node1)
-	tagNode1 := node1.(*mast.TagNode)
+	tagNode1, ok := node1.(*mast.TagNode)
+	require.True(t, ok, "Expected node1 to be *mast.TagNode")
 	assert.Equal(t, "tag1", string(tagNode1.Tag))
 
 	// Advance past the space
@@ -146,7 +148,8 @@ func TestTagParser_MultipleTags(t *testing.T) {
 	// Parse second tag
 	node2 := p.Parse(nil, reader, ctx)
 	require.NotNil(t, node2)
-	tagNode2 := node2.(*mast.TagNode)
+	tagNode2, ok := node2.(*mast.TagNode)
+	require.True(t, ok, "Expected node2 to be *mast.TagNode")
 	assert.Equal(t, "tag2", string(tagNode2.Tag))
 }
 
diff --git a/plugin/markdown/parser/wikilink.go b/plugin/markdown/parser/wikilink.go
index 9d026e439..492a1f370 100644
--- a/plugin/markdown/parser/wikilink.go
+++ b/plugin/markdown/parser/wikilink.go
@@ -12,7 +12,7 @@ import (
 
 type wikilinkParser struct{}
 
-// NewWikilinkParser creates a new inline parser for [[...]] wikilink syntax
+// NewWikilinkParser creates a new inline parser for [[...]] wikilink syntax.
 func NewWikilinkParser() parser.InlineParser {
 	return &wikilinkParser{}
 }
@@ -23,7 +23,7 @@ func (*wikilinkParser) Trigger() []byte {
 }
 
 // Parse parses [[target]] or [[target?params]] wikilink syntax.
-func (*wikilinkParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+func (*wikilinkParser) Parse(_ gast.Node, block text.Reader, _ parser.Context) gast.Node {
 	line, _ := block.PeekLine()
 
 	// Must start with [[
@@ -64,8 +64,8 @@ func (*wikilinkParser) Parse(parent gast.Node, block text.Reader, pc parser.Cont
 	return node
 }
 
-// findClosingBrackets finds the position of ]] in the byte slice
-// Returns -1 if not found
+// findClosingBrackets finds the position of ]] in the byte slice.
+// Returns -1 if not found.
 func findClosingBrackets(data []byte) int {
 	for i := 0; i < len(data)-1; i++ {
 		if data[i] == ']' && data[i+1] == ']' {
@@ -75,7 +75,7 @@ func findClosingBrackets(data []byte) int {
 	return -1
 }
 
-// parseTargetAndParams splits content on ? to extract target and parameters
+// parseTargetAndParams splits content on ? to extract target and parameters.
 func parseTargetAndParams(content []byte) (target []byte, params []byte) {
 	// Find ? separator
 	idx := bytes.IndexByte(content, '?')
diff --git a/plugin/markdown/parser/wikilink_test.go b/plugin/markdown/parser/wikilink_test.go
index 2501b6be3..33a8876cc 100644
--- a/plugin/markdown/parser/wikilink_test.go
+++ b/plugin/markdown/parser/wikilink_test.go
@@ -124,7 +124,8 @@ func TestWikilinkParser(t *testing.T) {
 				require.NotNil(t, node, "Expected wikilink to be parsed")
 				require.IsType(t, &mast.WikilinkNode{}, node)
 
-				wikilinkNode := node.(*mast.WikilinkNode)
+				wikilinkNode, ok := node.(*mast.WikilinkNode)
+				require.True(t, ok, "Expected node to be *mast.WikilinkNode")
 				assert.Equal(t, tt.expectedTarget, string(wikilinkNode.Target))
 				assert.Equal(t, tt.expectedParams, string(wikilinkNode.Params))
 			} else {
diff --git a/plugin/markdown/renderer/markdown_renderer.go b/plugin/markdown/renderer/markdown_renderer.go
index c63e79fa7..e9971d6be 100644
--- a/plugin/markdown/renderer/markdown_renderer.go
+++ b/plugin/markdown/renderer/markdown_renderer.go
@@ -252,7 +252,7 @@ func (r *MarkdownRenderer) renderListItem(node *gast.ListItem, source []byte, de
 
 	// Add list marker
 	if list.IsOrdered() {
-		r.buf.WriteString(fmt.Sprintf("%d. ", list.Start))
+		fmt.Fprintf(r.buf, "%d. ", list.Start)
 		list.Start++ // Increment for next item
 	} else {
 		r.buf.WriteString("- ")
diff --git a/server/router/api/v1/memo_service.go b/server/router/api/v1/memo_service.go
index 6270529c6..0bb90ecf8 100644
--- a/server/router/api/v1/memo_service.go
+++ b/server/router/api/v1/memo_service.go
@@ -6,7 +6,6 @@ import (
 	"log/slog"
 	"strings"
 	"time"
-	"unicode/utf8"
 
 	"github.com/lithammer/shortuuid/v4"
 	"github.com/pkg/errors"
@@ -845,25 +844,6 @@ func (s *APIV1Service) getMemoContentSnippet(content string) (string, error) {
 	return snippet, nil
 }
 
-func substring(s string, length int) string {
-	if length <= 0 {
-		return ""
-	}
-
-	runeCount := 0
-	byteIndex := 0
-	for byteIndex < len(s) {
-		_, size := utf8.DecodeRuneInString(s[byteIndex:])
-		byteIndex += size
-		runeCount++
-		if runeCount == length {
-			break
-		}
-	}
-
-	return s[:byteIndex]
-}
-
 // parseMemoOrderBy parses the order_by field and sets the appropriate ordering in memoFind.
 // Follows AIP-132: supports comma-separated list of fields with optional "desc" suffix.
 // Example: "pinned desc, display_time desc" or "create_time asc".