3 files changed, 19 insertions, 34 deletions

diff --git a/internal/tmuxedit/history.go b/internal/tmuxedit/history.go
index eab4db2..eac3114 100644
--- a/internal/tmuxedit/history.go
+++ b/internal/tmuxedit/history.go
@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"codeberg.org/snonux/hexai/internal/appconfig"
+	"codeberg.org/snonux/hexai/internal/textutil"
 )
 
 // HistoryEntry represents a single submission to the AI agent via tmux popup.
@@ -52,14 +53,15 @@ func AppendHistory(text, agent, cwd string) error {
 	if err != nil {
 		return fmt.Errorf("cannot open history file: %w", err)
 	}
-	defer f.Close()
+	defer func() { _ = f.Close() }() // best-effort on error paths
 
 	// Write entry
 	if _, err := f.Write(data); err != nil {
 		return fmt.Errorf("cannot write history entry: %w", err)
 	}
 
-	return nil
+	// Check Close error to catch deferred-write failures (e.g. disk full).
+	return f.Close()
 }
 
 // GetHistory retrieves the most recent history entries (up to limit).
@@ -84,7 +86,7 @@ func GetHistory(limit int) ([]HistoryEntry, error) {
 
 	// Parse JSONL line by line
 	var entries []HistoryEntry
-	lines := splitLines(data)
+	lines := textutil.SplitLinesBytes(data)
 	for i, line := range lines {
 		if len(line) == 0 {
 			continue // Skip empty lines
@@ -107,25 +109,3 @@ func GetHistory(limit int) ([]HistoryEntry, error) {
 
 	return entries, nil
 }
-
-// splitLines splits data into lines (handles both \n and \r\n)
-func splitLines(data []byte) [][]byte {
-	var lines [][]byte
-	start := 0
-	for i := 0; i < len(data); i++ {
-		if data[i] == '\n' {
-			// Include everything before the newline (excluding \r if present)
-			end := i
-			if end > start && data[end-1] == '\r' {
-				end--
-			}
-			lines = append(lines, data[start:end])
-			start = i + 1
-		}
-	}
-	// Handle last line if it doesn't end with newline
-	if start < len(data) {
-		lines = append(lines, data[start:])
-	}
-	return lines
-}
diff --git a/internal/tmuxedit/history_test.go b/internal/tmuxedit/history_test.go
index b9d59d3..f6d6d7d 100644
--- a/internal/tmuxedit/history_test.go
+++ b/internal/tmuxedit/history_test.go
@@ -6,6 +6,8 @@ import (
 	"path/filepath"
 	"testing"
 	"time"
+
+	"codeberg.org/snonux/hexai/internal/textutil"
 )
 
 func TestAppendHistory(t *testing.T) {
@@ -164,7 +166,7 @@ func TestSplitLines(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			got := splitLines([]byte(tt.input))
+			got := textutil.SplitLinesBytes([]byte(tt.input))
 			gotStr := make([]string, len(got))
 			for i, b := range got {
 				gotStr[i] = string(b)
diff --git a/internal/tmuxedit/run.go b/internal/tmuxedit/run.go
index efa503b..da484df 100644
--- a/internal/tmuxedit/run.go
+++ b/internal/tmuxedit/run.go
@@ -112,22 +112,23 @@ func loadConfig(configPath string) appconfig.App {
 var debugLog *log.Logger
 
 // initDebugLog creates a debug log file in the state directory
-// (~/.local/state/hexai/hexai-tmux-edit.log). Returns an error if the
-// state directory cannot be resolved. Silently skips logging if the
-// log file itself cannot be opened.
-func initDebugLog() error {
+// (~/.local/state/hexai/hexai-tmux-edit.log). Returns a closer for the
+// log file handle and an error if the state directory cannot be resolved.
+// Silently skips logging (returns a no-op closer) if the log file cannot
+// be opened.
+func initDebugLog() (func(), error) {
 	stateDir, err := appconfig.StateDir()
 	if err != nil {
-		return fmt.Errorf("cannot create state directory: %w", err)
+		return nil, fmt.Errorf("cannot create state directory: %w", err)
 	}
 
 	logPath := filepath.Join(stateDir, "hexai-tmux-edit.log")
 	f, err := os.OpenFile(logPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o644)
 	if err != nil {
-		return nil
+		return func() {}, nil
 	}
 	debugLog = log.New(f, "", log.LstdFlags|log.Lmicroseconds)
-	return nil
+	return func() { _ = f.Close() }, nil
 }
 
 func dbg(format string, args ...any) {
@@ -140,9 +141,11 @@ func dbg(format string, args ...any) {
 // It resolves the agent (by name or auto-detect), extracts the current
 // prompt, opens the editor popup, then clears and sends the result.
 func runWithConfig(opts Options, cfg appconfig.App) error {
-	if err := initDebugLog(); err != nil {
+	closeLog, err := initDebugLog()
+	if err != nil {
 		return fmt.Errorf("init debug log: %w", err)
 	}
+	defer closeLog()
 	dbg("=== hexai-tmux-edit start ===")
 	dbg("opts: pane=%q agent=%q config=%q", opts.Pane, opts.Agent, opts.ConfigPath)