Fix UTF-8 truncation for CJK/emoji characters

cmd/entire/cli/strategy/manual_commit_condensation.go

@@ -19,6 +19,7 @@ import (
 	"github.com/entireio/cli/cmd/entire/cli/paths"
 	"github.com/entireio/cli/cmd/entire/cli/session"
 	"github.com/entireio/cli/cmd/entire/cli/settings"
+	"github.com/entireio/cli/cmd/entire/cli/stringutil"
 	"github.com/entireio/cli/cmd/entire/cli/summarize"
 	"github.com/entireio/cli/cmd/entire/cli/textutil"
 	"github.com/entireio/cli/cmd/entire/cli/transcript"
@@ -679,11 +680,9 @@ func generateContextFromPrompts(prompts []string) []byte {
 	buf.WriteString("## User Prompts\n\n")
 
 	for i, prompt := range prompts {
-		// Truncate very long prompts for readability
-		displayPrompt := prompt
-		if len(displayPrompt) > 500 {
-			displayPrompt = displayPrompt[:500] + "..."
-		}
+		// Truncate very long prompts for readability.
+		// Use rune-based truncation to avoid splitting multi-byte UTF-8 characters (e.g. CJK).
+		displayPrompt := stringutil.TruncateRunes(prompt, 500, "...")
 		buf.WriteString(fmt.Sprintf("### Prompt %d\n\n", i+1))
 		buf.WriteString(displayPrompt)
 		buf.WriteString("\n\n")

cmd/entire/cli/strategy/manual_commit_condensation_test.go

@@ -0,0 +1,87 @@
+package strategy
+
+import (
+	"strings"
+	"testing"
+	"unicode/utf8"
+)
+
+func TestGenerateContextFromPrompts_CJKTruncation(t *testing.T) {
+	t.Parallel()
+
+	// 600 CJK characters exceeds the 500-rune truncation limit.
+	prompt := strings.Repeat("あ", 600)
+
+	result := generateContextFromPrompts([]string{prompt})
+
+	if !utf8.Valid(result) {
+		t.Error("generateContextFromPrompts produced invalid UTF-8 when truncating a CJK prompt")
+	}
+
+	resultStr := string(result)
+	if !strings.Contains(resultStr, "...") {
+		t.Error("expected truncated CJK prompt to contain '...' suffix")
+	}
+	// Should not contain more than 500 CJK characters
+	if strings.Contains(resultStr, strings.Repeat("あ", 501)) {
+		t.Error("CJK prompt was not truncated")
+	}
+}
+
+func TestGenerateContextFromPrompts_EmojiTruncation(t *testing.T) {
+	t.Parallel()
+
+	// 600 emoji exceeds the 500-rune truncation limit.
+	prompt := strings.Repeat("🎉", 600)
+
+	result := generateContextFromPrompts([]string{prompt})
+
+	if !utf8.Valid(result) {
+		t.Error("generateContextFromPrompts produced invalid UTF-8 when truncating an emoji prompt")
+	}
+
+	resultStr := string(result)
+	if !strings.Contains(resultStr, "...") {
+		t.Error("expected truncated emoji prompt to contain '...' suffix")
+	}
+}
+
+func TestGenerateContextFromPrompts_ASCIITruncation(t *testing.T) {
+	t.Parallel()
+
+	// Pure ASCII: should truncate at 500 runes with "..." suffix.
+	prompt := strings.Repeat("a", 600)
+
+	result := generateContextFromPrompts([]string{prompt})
+
+	if !utf8.Valid(result) {
+		t.Error("generateContextFromPrompts produced invalid UTF-8 when truncating an ASCII prompt")
+	}
+
+	resultStr := string(result)
+	if !strings.Contains(resultStr, "...") {
+		t.Error("expected truncated prompt to contain '...' suffix")
+	}
+
+	if strings.Contains(resultStr, strings.Repeat("a", 501)) {
+		t.Error("prompt was not truncated")
+	}
+}
+
+func TestGenerateContextFromPrompts_ShortCJKNotTruncated(t *testing.T) {
+	t.Parallel()
+
+	// 200 CJK characters is under the 500-rune limit, should not be truncated.
+	prompt := strings.Repeat("あ", 200)
+
+	result := generateContextFromPrompts([]string{prompt})
+
+	if !utf8.Valid(result) {
+		t.Error("generateContextFromPrompts produced invalid UTF-8")
+	}
+
+	resultStr := string(result)
+	if strings.Contains(resultStr, "...") {
+		t.Error("short CJK prompt should not be truncated")
+	}
+}

cmd/entire/cli/strategy/messages.go

@@ -3,22 +3,26 @@ package strategy
 import (
 	"encoding/json"
 	"fmt"
+	"unicode/utf8"
+
+	"github.com/entireio/cli/cmd/entire/cli/stringutil"
 )
 
 // MaxDescriptionLength is the maximum length for descriptions in commit messages
 // before truncation occurs.
 const MaxDescriptionLength = 60
 
-// TruncateDescription truncates a string to maxLen characters, adding "..." if truncated.
-// If maxLen is less than 3, returns a string of dots up to maxLen.
+// TruncateDescription truncates a string to maxLen runes, adding "..." if truncated.
+// Uses rune-based slicing to avoid splitting multi-byte UTF-8 characters.
+// If maxLen is less than 3, truncates without ellipsis.
 func TruncateDescription(s string, maxLen int) string {
-	if len(s) <= maxLen {
+	if utf8.RuneCountInString(s) <= maxLen {
 		return s
 	}
 	if maxLen < 3 {
-		return s[:maxLen]
+		return stringutil.TruncateRunes(s, maxLen, "")
 	}
-	return s[:maxLen-3] + "..."
+	return stringutil.TruncateRunes(s, maxLen, "...")
 }
 
 // FormatSubagentEndMessage formats a commit message for when a subagent completes.

cmd/entire/cli/stringutil/stringutil.go

@@ -21,11 +21,10 @@ func CollapseWhitespace(s string) string {
 // TruncateRunes truncates a string to at most maxRunes runes, appending suffix if truncated.
 // This is safe for multi-byte UTF-8 characters unlike byte-based slicing.
 func TruncateRunes(s string, maxRunes int, suffix string) string {
-	runes := []rune(s)
-	if len(runes) <= maxRunes {
+	if utf8.RuneCountInString(s) <= maxRunes {
 		return s
 	}
-	// Leave room for the suffix
+	runes := []rune(s)
 	suffixRunes := []rune(suffix)
 	truncateAt := maxRunes - len(suffixRunes)
 	if truncateAt < 0 {