fix: resolve review comment lines with blank snippets

internal/diff/resolver.go

@@ -75,6 +75,9 @@ type indexedLine struct {
 	content string
 }
 
+// maxMatchLineSpanFactor prevents matching snippets across excessive blank-line gaps.
+const maxMatchLineSpanFactor = 2
+
 // resolveFromHunk tries to find startLine/endLine by matching ExistingCode
 // against hunk lines. It tries the new-side first (context + added lines →
 // new-file line numbers), then falls back to old-side (context + deleted →
@@ -149,16 +152,30 @@ func matchConsecutive(sideLines []indexedLine, targetLines []string) (startLine,
 	if len(targetLines) == 0 || len(sideLines) < len(targetLines) {
 		return 0, 0, false
 	}
-	for i := 0; i <= len(sideLines)-len(targetLines); i++ {
-		matched := true
-		for j, target := range targetLines {
-			if sideLines[i+j].content != target {
-				matched = false
+	for i := 0; i < len(sideLines); i++ {
+		targetIndex := 0
+		start, end := 0, 0
+
+		for j := i; j < len(sideLines) && targetIndex < len(targetLines); j++ {
+			// ExistingCode normalization drops blank lines. Skip blank lines on the
+			// diff/file side as well so snippets containing internal blank lines
+			// can still resolve to their real line range.
+			if sideLines[j].content == "" {
+				continue
+			}
+			if sideLines[j].content != targetLines[targetIndex] {
 				break
 			}
+			if start == 0 {
+				start = sideLines[j].lineNum
+			}
+			end = sideLines[j].lineNum
+			targetIndex++
 		}
-		if matched {
-			return sideLines[i].lineNum, sideLines[i+len(targetLines)-1].lineNum, true
+		if targetIndex == len(targetLines) {
+			if end-start+1 <= len(targetLines)*maxMatchLineSpanFactor {
+				return start, end, true
+			}
 		}
 	}
 	return 0, 0, false
@@ -177,19 +194,17 @@ func resolveFromFileContent(d *model.Diff, cm *model.LlmComment) bool {
 		return false
 	}
 
-	for i := 0; i <= len(fileLines)-len(targetLines); i++ {
-		matched := true
-		for j, target := range targetLines {
-			if normalizeLine(strings.TrimRight(fileLines[i+j], "\r")) != target {
-				matched = false
-				break
-			}
-		}
-		if matched {
-			cm.StartLine = i + 1
-			cm.EndLine = i + len(targetLines)
-			return true
-		}
+	indexed := make([]indexedLine, 0, len(fileLines))
+	for i, line := range fileLines {
+		indexed = append(indexed, indexedLine{
+			lineNum: i + 1,
+			content: normalizeLine(strings.TrimRight(line, "\r")),
+		})
+	}
+	if start, end, ok := matchConsecutive(indexed, targetLines); ok {
+		cm.StartLine = start
+		cm.EndLine = end
+		return true
 	}
 
 	return false

internal/diff/resolver_test.go

@@ -117,6 +117,53 @@ import "fmt"`},
 	}
 }
 
+func TestResolveLineNumbers_NewFileSnippetWithInternalBlankLine(t *testing.T) {
+	raw := `diff --git a/internal/handler/file/file_handler_base.go b/internal/handler/file/file_handler_base.go
+new file mode 100644
+index 0000000..1b3ffb7
+--- /dev/null
++++ b/internal/handler/file/file_handler_base.go
+@@ -0,0 +1,17 @@
++package file
++
++import (
++	"example.com/acme/review-agent/internal/types"
++	"example.com/acme/review-agent/pkg/log"
++)
++
++// processFileTransfer processes file transfer with given direction
++func (h *Handler) processFileTransfer(fileInfo *types.FileInfo, direction string) *types.SystemStatus {
++	log.Infof("processing transfer: direction=%s, src=%s, dst=%s",
++		direction, fileInfo.SrcPath, fileInfo.DstPath)
++
++	if direction == "download" {
++		return h.performDownload(fileInfo.DstPath, nil)
++	}
++	return h.performUpload(fileInfo.SrcPath)
++}`
+
+	diffs := []model.Diff{
+		{NewPath: "internal/handler/file/file_handler_base.go", Diff: raw},
+	}
+	comments := []model.LlmComment{
+		{Path: "internal/handler/file/file_handler_base.go", ExistingCode: `func (h *Handler) processFileTransfer(fileInfo *types.FileInfo, direction string) *types.SystemStatus {
+	log.Infof("processing transfer: direction=%s, src=%s, dst=%s",
+		direction, fileInfo.SrcPath, fileInfo.DstPath)
+
+	if direction == "download" {
+		return h.performDownload(fileInfo.DstPath, nil)
+	}
+	return h.performUpload(fileInfo.SrcPath)
+}`},
+	}
+
+	result := ResolveLineNumbers(comments, diffs)
+	cm := result[0]
+	if cm.StartLine != 9 || cm.EndLine != 17 {
+		t.Errorf("new file with internal blank line: expected 9..17, got %d..%d", cm.StartLine, cm.EndLine)
+	}
+}
+
 func TestResolveLineNumbers_NoMatchKeepsZero(t *testing.T) {
 	diffs := []model.Diff{
 		{NewPath: "test.go", Diff: testDiff},
@@ -429,6 +476,34 @@ func TestMatchConsecutive_ExactFull(t *testing.T) {
 	}
 }
 
+func TestMatchConsecutive_SkipsInternalBlankLines(t *testing.T) {
+	lines := []indexedLine{
+		{lineNum: 10, content: "alpha"},
+		{lineNum: 11, content: ""},
+		{lineNum: 12, content: "beta"},
+	}
+
+	start, end, ok := matchConsecutive(lines, []string{"alpha", "beta"})
+	if !ok || start != 10 || end != 12 {
+		t.Errorf("blank-line match: got (%d, %d, %v), want (10, 12, true)", start, end, ok)
+	}
+}
+
+func TestMatchConsecutive_RejectsExcessiveBlankLineGap(t *testing.T) {
+	lines := []indexedLine{
+		{lineNum: 10, content: "alpha"},
+		{lineNum: 11, content: ""},
+		{lineNum: 12, content: ""},
+		{lineNum: 13, content: ""},
+		{lineNum: 14, content: "beta"},
+	}
+
+	start, end, ok := matchConsecutive(lines, []string{"alpha", "beta"})
+	if ok {
+		t.Errorf("expected excessive blank-line gap to be rejected, got (%d, %d, true)", start, end)
+	}
+}
+
 // ---------------------------------------------------------------------------
 // resolveFromHunk integration tests
 // ---------------------------------------------------------------------------