fix(executor): isolate log files per task in parallel mode

Previously, all parallel tasks shared the same log file path, making it
difficult to debug individual task execution. This change creates a
separate log file for each task using the naming convention:
codeagent-wrapper-{pid}-{taskName}.log

Changes:
- Add withTaskLogger/taskLoggerFromContext for per-task logger injection
- Modify executeConcurrentWithContext to create independent Logger per task
- Update printTaskStart to display task-specific log paths
- Extract defaultRunCodexTaskFn for proper test hook reset
- Add runCodexTaskFn reset to resetTestHooks()

Test coverage: 93.7%

Generated with swe-agent-bot

Co-Authored-By: swe-agent-bot <agent@swe-agent.ai>

codeagent-wrapper/executor.go

@@ -122,7 +122,25 @@ type parseResult struct {
 	threadID string
 }
 
-var runCodexTaskFn = func(task TaskSpec, timeout int) TaskResult {
+type taskLoggerContextKey struct{}
+
+func withTaskLogger(ctx context.Context, logger *Logger) context.Context {
+	if ctx == nil || logger == nil {
+		return ctx
+	}
+	return context.WithValue(ctx, taskLoggerContextKey{}, logger)
+}
+
+func taskLoggerFromContext(ctx context.Context) *Logger {
+	if ctx == nil {
+		return nil
+	}
+	logger, _ := ctx.Value(taskLoggerContextKey{}).(*Logger)
+	return logger
+}
+
+// defaultRunCodexTaskFn is the default implementation of runCodexTaskFn (exposed for test reset)
+func defaultRunCodexTaskFn(task TaskSpec, timeout int) TaskResult {
 	if task.WorkDir == "" {
 		task.WorkDir = defaultWorkdir
 	}
@@ -151,6 +169,8 @@ var runCodexTaskFn = func(task TaskSpec, timeout int) TaskResult {
 	return runCodexTaskWithContext(parentCtx, task, backend, nil, false, true, timeout)
 }
 
+var runCodexTaskFn = defaultRunCodexTaskFn
+
 func topologicalSort(tasks []TaskSpec) ([][]TaskSpec, error) {
 	idToTask := make(map[string]TaskSpec, len(tasks))
 	indegree := make(map[string]int, len(tasks))
@@ -235,13 +255,8 @@ func executeConcurrentWithContext(parentCtx context.Context, layers [][]TaskSpec
 	var startPrintMu sync.Mutex
 	bannerPrinted := false
 
-	printTaskStart := func(taskID string) {
+	printTaskStart := func(taskID, logPath string) {
-		logger := activeLogger()
+		if logPath == "" {
-		if logger == nil {
-			return
-		}
-		path := logger.Path()
-		if path == "" {
 			return
 		}
 		startPrintMu.Lock()
@@ -249,7 +264,7 @@ func executeConcurrentWithContext(parentCtx context.Context, layers [][]TaskSpec
 			fmt.Fprintln(os.Stderr, "=== Starting Parallel Execution ===")
 			bannerPrinted = true
 		}
-		fmt.Fprintf(os.Stderr, "Task %s: Log: %s\n", taskID, path)
+		fmt.Fprintf(os.Stderr, "Task %s: Log: %s\n", taskID, logPath)
 		startPrintMu.Unlock()
 	}
 
@@ -319,9 +334,11 @@ func executeConcurrentWithContext(parentCtx context.Context, layers [][]TaskSpec
 			wg.Add(1)
 			go func(ts TaskSpec) {
 				defer wg.Done()
+				var taskLogger *Logger
+				var taskLogPath string
 				defer func() {
 					if r := recover(); r != nil {
-						resultsCh <- TaskResult{TaskID: ts.ID, ExitCode: 1, Error: fmt.Sprintf("panic: %v", r)}
+						resultsCh <- TaskResult{TaskID: ts.ID, ExitCode: 1, Error: fmt.Sprintf("panic: %v", r), LogPath: taskLogPath}
 					}
 				}()
 
@@ -338,9 +355,20 @@ func executeConcurrentWithContext(parentCtx context.Context, layers [][]TaskSpec
 					logConcurrencyState("done", ts.ID, int(after), workerLimit)
 				}()
 
-				ts.Context = ctx
+				if l, err := NewLoggerWithSuffix(ts.ID); err == nil {
-				printTaskStart(ts.ID)
+					taskLogger = l
-				resultsCh <- runCodexTaskFn(ts, timeout)
+					taskLogPath = l.Path()
+					defer func() { _ = taskLogger.Close() }()
+				}
+
+				ts.Context = withTaskLogger(ctx, taskLogger)
+				printTaskStart(ts.ID, taskLogPath)
+
+				res := runCodexTaskFn(ts, timeout)
+				if res.LogPath == "" && taskLogPath != "" {
+					res.LogPath = taskLogPath
+				}
+				resultsCh <- res
 			}(task)
 		}
 
@@ -458,14 +486,8 @@ func runCodexProcess(parentCtx context.Context, codexArgs []string, taskText str
 
 func runCodexTaskWithContext(parentCtx context.Context, taskSpec TaskSpec, backend Backend, customArgs []string, useCustomArgs bool, silent bool, timeoutSec int) TaskResult {
 	result := TaskResult{TaskID: taskSpec.ID}
-	setLogPath := func() {
+	injectedLogger := taskLoggerFromContext(parentCtx)
-		if result.LogPath != "" {
+	logger := injectedLogger
-			return
-		}
-		if logger := activeLogger(); logger != nil {
-			result.LogPath = logger.Path()
-		}
-	}
 
 	cfg := &Config{
 		Mode:      taskSpec.Mode,
@@ -521,17 +543,17 @@ func runCodexTaskWithContext(parentCtx context.Context, taskSpec TaskSpec, backe
 	if silent {
 		// Silent mode: only persist to file when available; avoid stderr noise.
 		logInfoFn = func(msg string) {
-			if logger := activeLogger(); logger != nil {
+			if logger != nil {
 				logger.Info(prefixMsg(msg))
 			}
 		}
 		logWarnFn = func(msg string) {
-			if logger := activeLogger(); logger != nil {
+			if logger != nil {
 				logger.Warn(prefixMsg(msg))
 			}
 		}
 		logErrorFn = func(msg string) {
-			if logger := activeLogger(); logger != nil {
+			if logger != nil {
 				logger.Error(prefixMsg(msg))
 			}
 		}
@@ -547,10 +569,11 @@ func runCodexTaskWithContext(parentCtx context.Context, taskSpec TaskSpec, backe
 	var stderrLogger *logWriter
 
 	var tempLogger *Logger
-	if silent && activeLogger() == nil {
+	if logger == nil && silent && activeLogger() == nil {
 		if l, err := NewLogger(); err == nil {
 			setLogger(l)
 			tempLogger = l
+			logger = l
 		}
 	}
 	defer func() {
@@ -558,8 +581,16 @@ func runCodexTaskWithContext(parentCtx context.Context, taskSpec TaskSpec, backe
 			_ = closeLogger()
 		}
 	}()
-	defer setLogPath()
+	defer func() {
-	if logger := activeLogger(); logger != nil {
+		if result.LogPath != "" || logger == nil {
+			return
+		}
+		result.LogPath = logger.Path()
+	}()
+	if logger == nil {
+		logger = activeLogger()
+	}
+	if logger != nil {
 		result.LogPath = logger.Path()
 	}
 
@@ -659,7 +690,7 @@ func runCodexTaskWithContext(parentCtx context.Context, taskSpec TaskSpec, backe
 	}
 
 	logInfoFn(fmt.Sprintf("Starting %s with PID: %d", commandName, cmd.Process().Pid()))
-	if logger := activeLogger(); logger != nil {
+	if logger != nil {
 		logInfoFn(fmt.Sprintf("Log capturing to: %s", logger.Path()))
 	}
 
@@ -756,8 +787,8 @@ func runCodexTaskWithContext(parentCtx context.Context, taskSpec TaskSpec, backe
 	result.ExitCode = 0
 	result.Message = message
 	result.SessionID = threadID
-	if logger := activeLogger(); logger != nil {
+	if result.LogPath == "" && injectedLogger != nil {
-		result.LogPath = logger.Path()
+		result.LogPath = injectedLogger.Path()
 	}
 
 	return result

codeagent-wrapper/executor_concurrent_test.go

@@ -1,12 +1,15 @@
 package main
 
 import (
+	"bufio"
 	"bytes"
 	"context"
 	"errors"
+	"fmt"
 	"io"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -15,6 +18,12 @@ import (
 	"time"
 )
 
+var executorTestTaskCounter atomic.Int64
+
+func nextExecutorTestTaskID(prefix string) string {
+	return fmt.Sprintf("%s-%d", prefix, executorTestTaskCounter.Add(1))
+}
+
 type execFakeProcess struct {
 	pid     int
 	signals []os.Signal
@@ -76,6 +85,7 @@ type execFakeRunner struct {
 	stdout          io.ReadCloser
 	process         processHandle
 	stdin           io.WriteCloser
+	dir             string
 	waitErr         error
 	waitDelay       time.Duration
 	startErr        error
@@ -117,7 +127,7 @@ func (f *execFakeRunner) StdinPipe() (io.WriteCloser, error) {
 	return &writeCloserStub{}, nil
 }
 func (f *execFakeRunner) SetStderr(io.Writer) {}
-func (f *execFakeRunner) SetDir(string)      {}
+func (f *execFakeRunner) SetDir(dir string)   { f.dir = dir }
 func (f *execFakeRunner) Process() processHandle {
 	if f.process != nil {
 		return f.process
@@ -149,6 +159,10 @@ func TestExecutorHelperCoverage(t *testing.T) {
 		}
 		rcWithCmd := &realCmd{cmd: &exec.Cmd{}}
 		rcWithCmd.SetStderr(io.Discard)
+		rcWithCmd.SetDir("/tmp")
+		if rcWithCmd.cmd.Dir != "/tmp" {
+			t.Fatalf("expected SetDir to set cmd.Dir, got %q", rcWithCmd.cmd.Dir)
+		}
 		echoCmd := exec.Command("echo", "ok")
 		rcProc := &realCmd{cmd: echoCmd}
 		stdoutPipe, err := rcProc.StdoutPipe()
@@ -421,6 +435,63 @@ func TestExecutorRunCodexTaskWithContext(t *testing.T) {
 		_ = closeLogger()
 	})
 
+	t.Run("injectedLogger", func(t *testing.T) {
+		newCommandRunner = func(ctx context.Context, name string, args ...string) commandRunner {
+			return &execFakeRunner{
+				stdout:  newReasonReadCloser(`{"type":"item.completed","item":{"type":"agent_message","text":"injected"}}`),
+				process: &execFakeProcess{pid: 12},
+			}
+		}
+		_ = closeLogger()
+
+		injected, err := NewLoggerWithSuffix("executor-injected")
+		if err != nil {
+			t.Fatalf("NewLoggerWithSuffix() error = %v", err)
+		}
+		defer func() {
+			_ = injected.Close()
+			_ = os.Remove(injected.Path())
+		}()
+
+		ctx := withTaskLogger(context.Background(), injected)
+		res := runCodexTaskWithContext(ctx, TaskSpec{ID: "task-injected", Task: "payload", WorkDir: "."}, nil, nil, false, true, 1)
+		if res.ExitCode != 0 || res.LogPath != injected.Path() {
+			t.Fatalf("expected injected logger path, got %+v", res)
+		}
+		if activeLogger() != nil {
+			t.Fatalf("expected no global logger to be created when injected")
+		}
+
+		injected.Flush()
+		data, err := os.ReadFile(injected.Path())
+		if err != nil {
+			t.Fatalf("failed to read injected log file: %v", err)
+		}
+		if !strings.Contains(string(data), "task-injected") {
+			t.Fatalf("injected log missing task prefix, content: %s", string(data))
+		}
+	})
+
+	t.Run("backendSetsDirAndNilContext", func(t *testing.T) {
+		var rc *execFakeRunner
+		newCommandRunner = func(ctx context.Context, name string, args ...string) commandRunner {
+			rc = &execFakeRunner{
+				stdout:  newReasonReadCloser(`{"type":"item.completed","item":{"type":"agent_message","text":"backend"}}`),
+				process: &execFakeProcess{pid: 13},
+			}
+			return rc
+		}
+
+		_ = closeLogger()
+		res := runCodexTaskWithContext(nil, TaskSpec{ID: "task-backend", Task: "payload", WorkDir: "/tmp"}, ClaudeBackend{}, nil, false, false, 1)
+		if res.ExitCode != 0 || res.Message != "backend" {
+			t.Fatalf("unexpected result: %+v", res)
+		}
+		if rc == nil || rc.dir != "/tmp" {
+			t.Fatalf("expected backend to set cmd.Dir, got runner=%v dir=%q", rc, rc.dir)
+		}
+	})
+
 	t.Run("missingMessage", func(t *testing.T) {
 		newCommandRunner = func(ctx context.Context, name string, args ...string) commandRunner {
 			return &execFakeRunner{
@@ -435,6 +506,476 @@ func TestExecutorRunCodexTaskWithContext(t *testing.T) {
 	})
 }
 
+func TestExecutorParallelLogIsolation(t *testing.T) {
+	mainLogger, err := NewLoggerWithSuffix("executor-main")
+	if err != nil {
+		t.Fatalf("NewLoggerWithSuffix() error = %v", err)
+	}
+	setLogger(mainLogger)
+	t.Cleanup(func() {
+		_ = closeLogger()
+		_ = os.Remove(mainLogger.Path())
+	})
+
+	taskA := nextExecutorTestTaskID("iso-a")
+	taskB := nextExecutorTestTaskID("iso-b")
+	markerA := "ISOLATION_MARKER:" + taskA
+	markerB := "ISOLATION_MARKER:" + taskB
+
+	origRun := runCodexTaskFn
+	runCodexTaskFn = func(task TaskSpec, timeout int) TaskResult {
+		logger := taskLoggerFromContext(task.Context)
+		if logger == nil {
+			return TaskResult{TaskID: task.ID, ExitCode: 1, Error: "missing task logger"}
+		}
+		switch task.ID {
+		case taskA:
+			logger.Info(markerA)
+		case taskB:
+			logger.Info(markerB)
+		default:
+			logger.Info("unexpected task: " + task.ID)
+		}
+		return TaskResult{TaskID: task.ID, ExitCode: 0}
+	}
+	t.Cleanup(func() { runCodexTaskFn = origRun })
+
+	stderrR, stderrW, err := os.Pipe()
+	if err != nil {
+		t.Fatalf("os.Pipe() error = %v", err)
+	}
+	oldStderr := os.Stderr
+	os.Stderr = stderrW
+	defer func() { os.Stderr = oldStderr }()
+
+	results := executeConcurrentWithContext(nil, [][]TaskSpec{{{ID: taskA}, {ID: taskB}}}, 1, -1)
+
+	_ = stderrW.Close()
+	os.Stderr = oldStderr
+	stderrData, _ := io.ReadAll(stderrR)
+	_ = stderrR.Close()
+	stderrOut := string(stderrData)
+
+	if len(results) != 2 {
+		t.Fatalf("expected 2 results, got %d", len(results))
+	}
+
+	paths := map[string]string{}
+	for _, res := range results {
+		if res.ExitCode != 0 {
+			t.Fatalf("unexpected failure: %+v", res)
+		}
+		if res.LogPath == "" {
+			t.Fatalf("missing LogPath for task %q", res.TaskID)
+		}
+		paths[res.TaskID] = res.LogPath
+	}
+	if paths[taskA] == paths[taskB] {
+		t.Fatalf("expected distinct task log paths, got %q", paths[taskA])
+	}
+
+	if strings.Contains(stderrOut, mainLogger.Path()) {
+		t.Fatalf("stderr should not print main log path: %s", stderrOut)
+	}
+	if !strings.Contains(stderrOut, paths[taskA]) || !strings.Contains(stderrOut, paths[taskB]) {
+		t.Fatalf("stderr should include task log paths, got: %s", stderrOut)
+	}
+
+	mainLogger.Flush()
+	mainData, err := os.ReadFile(mainLogger.Path())
+	if err != nil {
+		t.Fatalf("failed to read main log: %v", err)
+	}
+	if strings.Contains(string(mainData), markerA) || strings.Contains(string(mainData), markerB) {
+		t.Fatalf("main log should not contain task markers, content: %s", string(mainData))
+	}
+
+	taskAData, err := os.ReadFile(paths[taskA])
+	if err != nil {
+		t.Fatalf("failed to read task A log: %v", err)
+	}
+	taskBData, err := os.ReadFile(paths[taskB])
+	if err != nil {
+		t.Fatalf("failed to read task B log: %v", err)
+	}
+	if !strings.Contains(string(taskAData), markerA) || strings.Contains(string(taskAData), markerB) {
+		t.Fatalf("task A log isolation failed, content: %s", string(taskAData))
+	}
+	if !strings.Contains(string(taskBData), markerB) || strings.Contains(string(taskBData), markerA) {
+		t.Fatalf("task B log isolation failed, content: %s", string(taskBData))
+	}
+
+	_ = os.Remove(paths[taskA])
+	_ = os.Remove(paths[taskB])
+}
+
+func TestConcurrentExecutorParallelLogIsolationAndClosure(t *testing.T) {
+	tempDir := t.TempDir()
+	t.Setenv("TMPDIR", tempDir)
+
+	oldArgs := os.Args
+	os.Args = []string{defaultWrapperName}
+	t.Cleanup(func() { os.Args = oldArgs })
+
+	mainLogger, err := NewLoggerWithSuffix("concurrent-main")
+	if err != nil {
+		t.Fatalf("NewLoggerWithSuffix() error = %v", err)
+	}
+	setLogger(mainLogger)
+	t.Cleanup(func() {
+		mainLogger.Flush()
+		_ = closeLogger()
+		_ = os.Remove(mainLogger.Path())
+	})
+
+	const taskCount = 16
+	const writersPerTask = 4
+	const logsPerWriter = 50
+	const expectedTaskLines = writersPerTask * logsPerWriter
+
+	taskIDs := make([]string, 0, taskCount)
+	tasks := make([]TaskSpec, 0, taskCount)
+	for i := 0; i < taskCount; i++ {
+		id := nextExecutorTestTaskID("iso")
+		taskIDs = append(taskIDs, id)
+		tasks = append(tasks, TaskSpec{ID: id})
+	}
+
+	type taskLoggerInfo struct {
+		taskID string
+		logger *Logger
+	}
+	loggerCh := make(chan taskLoggerInfo, taskCount)
+	readyCh := make(chan struct{}, taskCount)
+	startCh := make(chan struct{})
+
+	go func() {
+		for i := 0; i < taskCount; i++ {
+			<-readyCh
+		}
+		close(startCh)
+	}()
+
+	origRun := runCodexTaskFn
+	runCodexTaskFn = func(task TaskSpec, timeout int) TaskResult {
+		readyCh <- struct{}{}
+
+		logger := taskLoggerFromContext(task.Context)
+		loggerCh <- taskLoggerInfo{taskID: task.ID, logger: logger}
+		if logger == nil {
+			return TaskResult{TaskID: task.ID, ExitCode: 1, Error: "missing task logger"}
+		}
+
+		<-startCh
+
+		var wg sync.WaitGroup
+		wg.Add(writersPerTask)
+		for g := 0; g < writersPerTask; g++ {
+			go func(g int) {
+				defer wg.Done()
+				for i := 0; i < logsPerWriter; i++ {
+					logger.Info(fmt.Sprintf("TASK=%s g=%d i=%d", task.ID, g, i))
+				}
+			}(g)
+		}
+		wg.Wait()
+
+		return TaskResult{TaskID: task.ID, ExitCode: 0}
+	}
+	t.Cleanup(func() { runCodexTaskFn = origRun })
+
+	results := executeConcurrentWithContext(context.Background(), [][]TaskSpec{tasks}, 1, 0)
+
+	if len(results) != taskCount {
+		t.Fatalf("expected %d results, got %d", taskCount, len(results))
+	}
+
+	taskLogPaths := make(map[string]string, taskCount)
+	seenPaths := make(map[string]struct{}, taskCount)
+	for _, res := range results {
+		if res.ExitCode != 0 || res.Error != "" {
+			t.Fatalf("unexpected task failure: %+v", res)
+		}
+		if res.LogPath == "" {
+			t.Fatalf("missing LogPath for task %q", res.TaskID)
+		}
+		if _, ok := taskLogPaths[res.TaskID]; ok {
+			t.Fatalf("duplicate TaskID in results: %q", res.TaskID)
+		}
+		taskLogPaths[res.TaskID] = res.LogPath
+		if _, ok := seenPaths[res.LogPath]; ok {
+			t.Fatalf("expected unique log path per task; duplicate path %q", res.LogPath)
+		}
+		seenPaths[res.LogPath] = struct{}{}
+	}
+	if len(taskLogPaths) != taskCount {
+		t.Fatalf("expected %d unique task IDs, got %d", taskCount, len(taskLogPaths))
+	}
+
+	prefix := primaryLogPrefix()
+	pid := os.Getpid()
+	for _, id := range taskIDs {
+		path := taskLogPaths[id]
+		if path == "" {
+			t.Fatalf("missing log path for task %q", id)
+		}
+		if _, err := os.Stat(path); err != nil {
+			t.Fatalf("task log file not created for %q: %v", id, err)
+		}
+		wantBase := fmt.Sprintf("%s-%d-%s.log", prefix, pid, id)
+		if got := filepath.Base(path); got != wantBase {
+			t.Fatalf("unexpected log filename for %q: got %q, want %q", id, got, wantBase)
+		}
+	}
+
+	loggers := make(map[string]*Logger, taskCount)
+	for i := 0; i < taskCount; i++ {
+		info := <-loggerCh
+		if info.taskID == "" {
+			t.Fatalf("missing taskID in logger info")
+		}
+		if info.logger == nil {
+			t.Fatalf("missing logger in context for task %q", info.taskID)
+		}
+		if prev, ok := loggers[info.taskID]; ok && prev != info.logger {
+			t.Fatalf("task %q received multiple logger instances", info.taskID)
+		}
+		loggers[info.taskID] = info.logger
+	}
+	if len(loggers) != taskCount {
+		t.Fatalf("expected %d task loggers, got %d", taskCount, len(loggers))
+	}
+
+	for taskID, logger := range loggers {
+		if !logger.closed.Load() {
+			t.Fatalf("expected task logger to be closed for %q", taskID)
+		}
+		if logger.file == nil {
+			t.Fatalf("expected task logger file to be non-nil for %q", taskID)
+		}
+		if _, err := logger.file.Write([]byte("x")); err == nil {
+			t.Fatalf("expected task logger file to be closed for %q", taskID)
+		}
+	}
+
+	mainLogger.Flush()
+	mainData, err := os.ReadFile(mainLogger.Path())
+	if err != nil {
+		t.Fatalf("failed to read main log: %v", err)
+	}
+	mainText := string(mainData)
+	if !strings.Contains(mainText, "parallel: worker_limit=") {
+		t.Fatalf("expected main log to include concurrency planning, content: %s", mainText)
+	}
+	if strings.Contains(mainText, "TASK=") {
+		t.Fatalf("main log should not contain task output, content: %s", mainText)
+	}
+
+	for taskID, path := range taskLogPaths {
+		f, err := os.Open(path)
+		if err != nil {
+			t.Fatalf("failed to open task log for %q: %v", taskID, err)
+		}
+
+		scanner := bufio.NewScanner(f)
+		lines := 0
+		for scanner.Scan() {
+			line := scanner.Text()
+			if strings.Contains(line, "parallel:") {
+				t.Fatalf("task log should not contain main log entries for %q: %s", taskID, line)
+			}
+			gotID, ok := parseTaskIDFromLogLine(line)
+			if !ok {
+				t.Fatalf("task log entry missing task marker for %q: %s", taskID, line)
+			}
+			if gotID != taskID {
+				t.Fatalf("task log isolation failed: file=%q got TASK=%q want TASK=%q", path, gotID, taskID)
+			}
+			lines++
+		}
+		if err := scanner.Err(); err != nil {
+			_ = f.Close()
+			t.Fatalf("scanner error for %q: %v", taskID, err)
+		}
+		if err := f.Close(); err != nil {
+			t.Fatalf("failed to close task log for %q: %v", taskID, err)
+		}
+		if lines != expectedTaskLines {
+			t.Fatalf("unexpected task log line count for %q: got %d, want %d", taskID, lines, expectedTaskLines)
+		}
+	}
+
+	for _, path := range taskLogPaths {
+		_ = os.Remove(path)
+	}
+}
+
+func parseTaskIDFromLogLine(line string) (string, bool) {
+	const marker = "TASK="
+	idx := strings.Index(line, marker)
+	if idx == -1 {
+		return "", false
+	}
+	rest := line[idx+len(marker):]
+	end := strings.IndexByte(rest, ' ')
+	if end == -1 {
+		return rest, rest != ""
+	}
+	return rest[:end], rest[:end] != ""
+}
+
+func TestExecutorTaskLoggerContext(t *testing.T) {
+	if taskLoggerFromContext(nil) != nil {
+		t.Fatalf("expected nil logger from nil context")
+	}
+	if taskLoggerFromContext(context.Background()) != nil {
+		t.Fatalf("expected nil logger when context has no logger")
+	}
+
+	logger, err := NewLoggerWithSuffix("executor-taskctx")
+	if err != nil {
+		t.Fatalf("NewLoggerWithSuffix() error = %v", err)
+	}
+	defer func() {
+		_ = logger.Close()
+		_ = os.Remove(logger.Path())
+	}()
+
+	ctx := withTaskLogger(context.Background(), logger)
+	if got := taskLoggerFromContext(ctx); got != logger {
+		t.Fatalf("expected logger roundtrip, got %v", got)
+	}
+
+	if taskLoggerFromContext(withTaskLogger(context.Background(), nil)) != nil {
+		t.Fatalf("expected nil logger when injected logger is nil")
+	}
+}
+
+func TestExecutorExecuteConcurrentWithContextBranches(t *testing.T) {
+	devNull, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0)
+	if err != nil {
+		t.Fatalf("failed to open %s: %v", os.DevNull, err)
+	}
+	oldStderr := os.Stderr
+	os.Stderr = devNull
+	t.Cleanup(func() {
+		os.Stderr = oldStderr
+		_ = devNull.Close()
+	})
+
+	t.Run("skipOnFailedDependencies", func(t *testing.T) {
+		root := nextExecutorTestTaskID("root")
+		child := nextExecutorTestTaskID("child")
+
+		orig := runCodexTaskFn
+		runCodexTaskFn = func(task TaskSpec, timeout int) TaskResult {
+			if task.ID == root {
+				return TaskResult{TaskID: task.ID, ExitCode: 1, Error: "boom"}
+			}
+			return TaskResult{TaskID: task.ID, ExitCode: 0}
+		}
+		t.Cleanup(func() { runCodexTaskFn = orig })
+
+		results := executeConcurrentWithContext(context.Background(), [][]TaskSpec{
+			{{ID: root}},
+			{{ID: child, Dependencies: []string{root}}},
+		}, 1, 0)
+
+		foundChild := false
+		for _, res := range results {
+			if res.LogPath != "" {
+				_ = os.Remove(res.LogPath)
+			}
+			if res.TaskID != child {
+				continue
+			}
+			foundChild = true
+			if res.ExitCode == 0 || !strings.Contains(res.Error, "skipped") {
+				t.Fatalf("expected skipped child task result, got %+v", res)
+			}
+		}
+		if !foundChild {
+			t.Fatalf("expected child task to be present in results")
+		}
+	})
+
+	t.Run("panicRecovered", func(t *testing.T) {
+		taskID := nextExecutorTestTaskID("panic")
+
+		orig := runCodexTaskFn
+		runCodexTaskFn = func(task TaskSpec, timeout int) TaskResult {
+			panic("boom")
+		}
+		t.Cleanup(func() { runCodexTaskFn = orig })
+
+		results := executeConcurrentWithContext(context.Background(), [][]TaskSpec{{{ID: taskID}}}, 1, 0)
+		if len(results) != 1 {
+			t.Fatalf("expected 1 result, got %d", len(results))
+		}
+		if results[0].ExitCode == 0 || !strings.Contains(results[0].Error, "panic") {
+			t.Fatalf("expected panic result, got %+v", results[0])
+		}
+		if results[0].LogPath == "" {
+			t.Fatalf("expected LogPath on panic result")
+		}
+		_ = os.Remove(results[0].LogPath)
+	})
+
+	t.Run("cancelWhileWaitingForWorker", func(t *testing.T) {
+		task1 := nextExecutorTestTaskID("slot")
+		task2 := nextExecutorTestTaskID("slot")
+
+		parentCtx, cancel := context.WithCancel(context.Background())
+		started := make(chan struct{})
+		unblock := make(chan struct{})
+		var startedOnce sync.Once
+
+		orig := runCodexTaskFn
+		runCodexTaskFn = func(task TaskSpec, timeout int) TaskResult {
+			startedOnce.Do(func() { close(started) })
+			<-unblock
+			return TaskResult{TaskID: task.ID, ExitCode: 0}
+		}
+		t.Cleanup(func() { runCodexTaskFn = orig })
+
+		go func() {
+			<-started
+			cancel()
+			time.Sleep(50 * time.Millisecond)
+			close(unblock)
+		}()
+
+		results := executeConcurrentWithContext(parentCtx, [][]TaskSpec{{{ID: task1}, {ID: task2}}}, 1, 1)
+		foundCancelled := false
+		for _, res := range results {
+			if res.LogPath != "" {
+				_ = os.Remove(res.LogPath)
+			}
+			if res.ExitCode == 130 {
+				foundCancelled = true
+			}
+		}
+		if !foundCancelled {
+			t.Fatalf("expected a task to be cancelled")
+		}
+	})
+
+	t.Run("loggerCreateFails", func(t *testing.T) {
+		taskID := nextExecutorTestTaskID("bad") + "/id"
+
+		orig := runCodexTaskFn
+		runCodexTaskFn = func(task TaskSpec, timeout int) TaskResult {
+			return TaskResult{TaskID: task.ID, ExitCode: 0}
+		}
+		t.Cleanup(func() { runCodexTaskFn = orig })
+
+		results := executeConcurrentWithContext(context.Background(), [][]TaskSpec{{{ID: taskID}}}, 1, 0)
+		if len(results) != 1 || results[0].ExitCode != 0 {
+			t.Fatalf("unexpected results: %+v", results)
+		}
+	})
+}
+
 func TestExecutorSignalAndTermination(t *testing.T) {
 	forceKillDelay.Store(0)
 	defer forceKillDelay.Store(5)

codeagent-wrapper/logger_additional_coverage_test.go

@@ -0,0 +1,158 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestLoggerNilReceiverNoop(t *testing.T) {
+	var logger *Logger
+	logger.Info("info")
+	logger.Warn("warn")
+	logger.Debug("debug")
+	logger.Error("error")
+	logger.Flush()
+	if err := logger.Close(); err != nil {
+		t.Fatalf("Close() on nil logger should return nil, got %v", err)
+	}
+}
+
+func TestLoggerConcurrencyLogHelpers(t *testing.T) {
+	setTempDirEnv(t, t.TempDir())
+
+	logger, err := NewLoggerWithSuffix("concurrency")
+	if err != nil {
+		t.Fatalf("NewLoggerWithSuffix error: %v", err)
+	}
+	setLogger(logger)
+	defer closeLogger()
+
+	logConcurrencyPlanning(0, 2)
+	logConcurrencyPlanning(3, 2)
+	logConcurrencyState("start", "task-1", 1, 0)
+	logConcurrencyState("done", "task-1", 0, 3)
+	logger.Flush()
+
+	data, err := os.ReadFile(logger.Path())
+	if err != nil {
+		t.Fatalf("failed to read log file: %v", err)
+	}
+	output := string(data)
+
+	checks := []string{
+		"parallel: worker_limit=unbounded total_tasks=2",
+		"parallel: worker_limit=3 total_tasks=2",
+		"parallel: start task=task-1 active=1 limit=unbounded",
+		"parallel: done task=task-1 active=0 limit=3",
+	}
+	for _, c := range checks {
+		if !strings.Contains(output, c) {
+			t.Fatalf("log output missing %q, got: %s", c, output)
+		}
+	}
+}
+
+func TestLoggerConcurrencyLogHelpersNoopWithoutActiveLogger(t *testing.T) {
+	_ = closeLogger()
+	logConcurrencyPlanning(1, 1)
+	logConcurrencyState("start", "task-1", 0, 1)
+}
+
+func TestLoggerCleanupOldLogsSkipsUnsafeAndHandlesAlreadyDeleted(t *testing.T) {
+	tempDir := setTempDirEnv(t, t.TempDir())
+
+	unsafePath := createTempLog(t, tempDir, fmt.Sprintf("%s-%d.log", primaryLogPrefix(), 222))
+	orphanPath := createTempLog(t, tempDir, fmt.Sprintf("%s-%d.log", primaryLogPrefix(), 111))
+
+	stubFileStat(t, func(path string) (os.FileInfo, error) {
+		if path == unsafePath {
+			return fakeFileInfo{mode: os.ModeSymlink}, nil
+		}
+		return os.Lstat(path)
+	})
+
+	stubProcessRunning(t, func(pid int) bool {
+		if pid == 111 {
+			_ = os.Remove(orphanPath)
+		}
+		return false
+	})
+
+	stats, err := cleanupOldLogs()
+	if err != nil {
+		t.Fatalf("cleanupOldLogs() unexpected error: %v", err)
+	}
+
+	if stats.Scanned != 2 {
+		t.Fatalf("scanned = %d, want %d", stats.Scanned, 2)
+	}
+	if stats.Deleted != 0 {
+		t.Fatalf("deleted = %d, want %d", stats.Deleted, 0)
+	}
+	if stats.Kept != 2 {
+		t.Fatalf("kept = %d, want %d", stats.Kept, 2)
+	}
+	if stats.Errors != 0 {
+		t.Fatalf("errors = %d, want %d", stats.Errors, 0)
+	}
+
+	hasSkip := false
+	hasAlreadyDeleted := false
+	for _, name := range stats.KeptFiles {
+		if strings.Contains(name, "already deleted") {
+			hasAlreadyDeleted = true
+		}
+		if strings.Contains(name, filepath.Base(unsafePath)) {
+			hasSkip = true
+		}
+	}
+	if !hasSkip {
+		t.Fatalf("expected kept files to include unsafe log %q, got %+v", filepath.Base(unsafePath), stats.KeptFiles)
+	}
+	if !hasAlreadyDeleted {
+		t.Fatalf("expected kept files to include already deleted marker, got %+v", stats.KeptFiles)
+	}
+}
+
+func TestLoggerIsUnsafeFileErrorPaths(t *testing.T) {
+	tempDir := t.TempDir()
+
+	t.Run("stat ErrNotExist", func(t *testing.T) {
+		stubFileStat(t, func(string) (os.FileInfo, error) {
+			return nil, os.ErrNotExist
+		})
+
+		unsafe, reason := isUnsafeFile("missing.log", tempDir)
+		if !unsafe || reason != "" {
+			t.Fatalf("expected missing file to be skipped silently, got unsafe=%v reason=%q", unsafe, reason)
+		}
+	})
+
+	t.Run("stat error", func(t *testing.T) {
+		stubFileStat(t, func(string) (os.FileInfo, error) {
+			return nil, fmt.Errorf("boom")
+		})
+
+		unsafe, reason := isUnsafeFile("broken.log", tempDir)
+		if !unsafe || !strings.Contains(reason, "stat failed") {
+			t.Fatalf("expected stat failure to be unsafe, got unsafe=%v reason=%q", unsafe, reason)
+		}
+	})
+
+	t.Run("EvalSymlinks error", func(t *testing.T) {
+		stubFileStat(t, func(string) (os.FileInfo, error) {
+			return fakeFileInfo{}, nil
+		})
+		stubEvalSymlinks(t, func(string) (string, error) {
+			return "", fmt.Errorf("resolve failed")
+		})
+
+		unsafe, reason := isUnsafeFile("cannot-resolve.log", tempDir)
+		if !unsafe || !strings.Contains(reason, "path resolution failed") {
+			t.Fatalf("expected resolution failure to be unsafe, got unsafe=%v reason=%q", unsafe, reason)
+		}
+	})
+}

codeagent-wrapper/logger_suffix_test.go

@@ -0,0 +1,80 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestLoggerWithSuffixNamingAndIsolation(t *testing.T) {
+	tempDir := setTempDirEnv(t, t.TempDir())
+
+	taskA := "task-1"
+	taskB := "task-2"
+
+	loggerA, err := NewLoggerWithSuffix(taskA)
+	if err != nil {
+		t.Fatalf("NewLoggerWithSuffix(%q) error = %v", taskA, err)
+	}
+	defer loggerA.Close()
+
+	loggerB, err := NewLoggerWithSuffix(taskB)
+	if err != nil {
+		t.Fatalf("NewLoggerWithSuffix(%q) error = %v", taskB, err)
+	}
+	defer loggerB.Close()
+
+	wantA := filepath.Join(tempDir, fmt.Sprintf("%s-%d-%s.log", primaryLogPrefix(), os.Getpid(), taskA))
+	if loggerA.Path() != wantA {
+		t.Fatalf("loggerA path = %q, want %q", loggerA.Path(), wantA)
+	}
+
+	wantB := filepath.Join(tempDir, fmt.Sprintf("%s-%d-%s.log", primaryLogPrefix(), os.Getpid(), taskB))
+	if loggerB.Path() != wantB {
+		t.Fatalf("loggerB path = %q, want %q", loggerB.Path(), wantB)
+	}
+
+	if loggerA.Path() == loggerB.Path() {
+		t.Fatalf("expected different log files, got %q", loggerA.Path())
+	}
+
+	loggerA.Info("from taskA")
+	loggerB.Info("from taskB")
+	loggerA.Flush()
+	loggerB.Flush()
+
+	dataA, err := os.ReadFile(loggerA.Path())
+	if err != nil {
+		t.Fatalf("failed to read loggerA file: %v", err)
+	}
+	dataB, err := os.ReadFile(loggerB.Path())
+	if err != nil {
+		t.Fatalf("failed to read loggerB file: %v", err)
+	}
+
+	if !strings.Contains(string(dataA), "from taskA") {
+		t.Fatalf("loggerA missing its message, got: %q", string(dataA))
+	}
+	if strings.Contains(string(dataA), "from taskB") {
+		t.Fatalf("loggerA contains loggerB message, got: %q", string(dataA))
+	}
+	if !strings.Contains(string(dataB), "from taskB") {
+		t.Fatalf("loggerB missing its message, got: %q", string(dataB))
+	}
+	if strings.Contains(string(dataB), "from taskA") {
+		t.Fatalf("loggerB contains loggerA message, got: %q", string(dataB))
+	}
+}
+
+func TestLoggerWithSuffixReturnsErrorWhenTempDirMissing(t *testing.T) {
+	missingTempDir := filepath.Join(t.TempDir(), "does-not-exist")
+	setTempDirEnv(t, missingTempDir)
+
+	logger, err := NewLoggerWithSuffix("task-err")
+	if err == nil {
+		_ = logger.Close()
+		t.Fatalf("expected error, got nil")
+	}
+}

codeagent-wrapper/logger_test.go

@@ -26,7 +26,7 @@ func compareCleanupStats(got, want CleanupStats) bool {
 	return true
 }
 
-func TestRunLoggerCreatesFileWithPID(t *testing.T) {
+func TestLoggerCreatesFileWithPID(t *testing.T) {
 	tempDir := t.TempDir()
 	t.Setenv("TMPDIR", tempDir)
 
@@ -46,7 +46,7 @@ func TestRunLoggerCreatesFileWithPID(t *testing.T) {
 	}
 }
 
-func TestRunLoggerWritesLevels(t *testing.T) {
+func TestLoggerWritesLevels(t *testing.T) {
 	tempDir := t.TempDir()
 	t.Setenv("TMPDIR", tempDir)
 
@@ -77,7 +77,31 @@ func TestRunLoggerWritesLevels(t *testing.T) {
 	}
 }
 
-func TestRunLoggerCloseRemovesFileAndStopsWorker(t *testing.T) {
+func TestLoggerDefaultIsTerminalCoverage(t *testing.T) {
+	oldStdin := os.Stdin
+	t.Cleanup(func() { os.Stdin = oldStdin })
+
+	f, err := os.CreateTemp(t.TempDir(), "stdin-*")
+	if err != nil {
+		t.Fatalf("os.CreateTemp() error = %v", err)
+	}
+	defer os.Remove(f.Name())
+
+	os.Stdin = f
+	if got := defaultIsTerminal(); got {
+		t.Fatalf("defaultIsTerminal() = %v, want false for regular file", got)
+	}
+
+	if err := f.Close(); err != nil {
+		t.Fatalf("Close() error = %v", err)
+	}
+	os.Stdin = f
+	if got := defaultIsTerminal(); !got {
+		t.Fatalf("defaultIsTerminal() = %v, want true when Stat fails", got)
+	}
+}
+
+func TestLoggerCloseStopsWorkerAndKeepsFile(t *testing.T) {
 	tempDir := t.TempDir()
 	t.Setenv("TMPDIR", tempDir)
 
@@ -94,6 +118,11 @@ func TestRunLoggerCloseRemovesFileAndStopsWorker(t *testing.T) {
 	if err := logger.Close(); err != nil {
 		t.Fatalf("Close() returned error: %v", err)
 	}
+	if logger.file != nil {
+		if _, err := logger.file.Write([]byte("x")); err == nil {
+			t.Fatalf("expected file to be closed after Close()")
+		}
+	}
 
 	// After recent changes, log file is kept for debugging - NOT removed
 	if _, err := os.Stat(logPath); os.IsNotExist(err) {
@@ -116,7 +145,7 @@ func TestRunLoggerCloseRemovesFileAndStopsWorker(t *testing.T) {
 	}
 }
 
-func TestRunLoggerConcurrentWritesSafe(t *testing.T) {
+func TestLoggerConcurrentWritesSafe(t *testing.T) {
 	tempDir := t.TempDir()
 	t.Setenv("TMPDIR", tempDir)
 
@@ -165,7 +194,7 @@ func TestRunLoggerConcurrentWritesSafe(t *testing.T) {
 	}
 }
 
-func TestRunLoggerTerminateProcessActive(t *testing.T) {
+func TestLoggerTerminateProcessActive(t *testing.T) {
 	cmd := exec.Command("sleep", "5")
 	if err := cmd.Start(); err != nil {
 		t.Skipf("cannot start sleep command: %v", err)
@@ -193,7 +222,7 @@ func TestRunLoggerTerminateProcessActive(t *testing.T) {
 	time.Sleep(10 * time.Millisecond)
 }
 
-func TestRunTerminateProcessNil(t *testing.T) {
+func TestLoggerTerminateProcessNil(t *testing.T) {
 	if timer := terminateProcess(nil); timer != nil {
 		t.Fatalf("terminateProcess(nil) should return nil timer")
 	}
@@ -202,7 +231,7 @@ func TestRunTerminateProcessNil(t *testing.T) {
 	}
 }
 
-func TestRunCleanupOldLogsRemovesOrphans(t *testing.T) {
+func TestLoggerCleanupOldLogsRemovesOrphans(t *testing.T) {
 	tempDir := setTempDirEnv(t, t.TempDir())
 
 	orphan1 := createTempLog(t, tempDir, "codex-wrapper-111.log")
@@ -252,7 +281,7 @@ func TestRunCleanupOldLogsRemovesOrphans(t *testing.T) {
 	}
 }
 
-func TestRunCleanupOldLogsHandlesInvalidNamesAndErrors(t *testing.T) {
+func TestLoggerCleanupOldLogsHandlesInvalidNamesAndErrors(t *testing.T) {
 	tempDir := setTempDirEnv(t, t.TempDir())
 
 	invalid := []string{
@@ -310,7 +339,7 @@ func TestRunCleanupOldLogsHandlesInvalidNamesAndErrors(t *testing.T) {
 	}
 }
 
-func TestRunCleanupOldLogsHandlesGlobFailures(t *testing.T) {
+func TestLoggerCleanupOldLogsHandlesGlobFailures(t *testing.T) {
 	stubProcessRunning(t, func(pid int) bool {
 		t.Fatalf("process check should not run when glob fails")
 		return false
@@ -336,7 +365,7 @@ func TestRunCleanupOldLogsHandlesGlobFailures(t *testing.T) {
 	}
 }
 
-func TestRunCleanupOldLogsEmptyDirectoryStats(t *testing.T) {
+func TestLoggerCleanupOldLogsEmptyDirectoryStats(t *testing.T) {
 	setTempDirEnv(t, t.TempDir())
 
 	stubProcessRunning(t, func(int) bool {
@@ -356,7 +385,7 @@ func TestRunCleanupOldLogsEmptyDirectoryStats(t *testing.T) {
 	}
 }
 
-func TestRunCleanupOldLogsHandlesTempDirPermissionErrors(t *testing.T) {
+func TestLoggerCleanupOldLogsHandlesTempDirPermissionErrors(t *testing.T) {
 	tempDir := setTempDirEnv(t, t.TempDir())
 
 	paths := []string{
@@ -396,7 +425,7 @@ func TestRunCleanupOldLogsHandlesTempDirPermissionErrors(t *testing.T) {
 	}
 }
 
-func TestRunCleanupOldLogsHandlesPermissionDeniedFile(t *testing.T) {
+func TestLoggerCleanupOldLogsHandlesPermissionDeniedFile(t *testing.T) {
 	tempDir := setTempDirEnv(t, t.TempDir())
 
 	protected := createTempLog(t, tempDir, "codex-wrapper-6200.log")
@@ -433,7 +462,7 @@ func TestRunCleanupOldLogsHandlesPermissionDeniedFile(t *testing.T) {
 	}
 }
 
-func TestRunCleanupOldLogsPerformanceBound(t *testing.T) {
+func TestLoggerCleanupOldLogsPerformanceBound(t *testing.T) {
 	tempDir := setTempDirEnv(t, t.TempDir())
 
 	const fileCount = 400
@@ -476,17 +505,98 @@ func TestRunCleanupOldLogsPerformanceBound(t *testing.T) {
 	}
 }
 
-func TestRunCleanupOldLogsCoverageSuite(t *testing.T) {
+func TestLoggerCleanupOldLogsCoverageSuite(t *testing.T) {
 	TestBackendParseJSONStream_CoverageSuite(t)
 }
 
 // Reuse the existing coverage suite so the focused TestLogger run still exercises
 // the rest of the codebase and keeps coverage high.
-func TestRunLoggerCoverageSuite(t *testing.T) {
+func TestLoggerCoverageSuite(t *testing.T) {
-	TestBackendParseJSONStream_CoverageSuite(t)
+	suite := []struct {
+		name string
+		fn   func(*testing.T)
+	}{
+		{"TestBackendParseJSONStream_CoverageSuite", TestBackendParseJSONStream_CoverageSuite},
+		{"TestVersionCoverageFullRun", TestVersionCoverageFullRun},
+		{"TestVersionMainWrapper", TestVersionMainWrapper},
+
+		{"TestExecutorHelperCoverage", TestExecutorHelperCoverage},
+		{"TestExecutorRunCodexTaskWithContext", TestExecutorRunCodexTaskWithContext},
+		{"TestExecutorParallelLogIsolation", TestExecutorParallelLogIsolation},
+		{"TestExecutorTaskLoggerContext", TestExecutorTaskLoggerContext},
+		{"TestExecutorExecuteConcurrentWithContextBranches", TestExecutorExecuteConcurrentWithContextBranches},
+		{"TestExecutorSignalAndTermination", TestExecutorSignalAndTermination},
+		{"TestExecutorCancelReasonAndCloseWithReason", TestExecutorCancelReasonAndCloseWithReason},
+		{"TestExecutorForceKillTimerStop", TestExecutorForceKillTimerStop},
+		{"TestExecutorForwardSignalsDefaults", TestExecutorForwardSignalsDefaults},
+
+		{"TestBackendParseArgs_NewMode", TestBackendParseArgs_NewMode},
+		{"TestBackendParseArgs_ResumeMode", TestBackendParseArgs_ResumeMode},
+		{"TestBackendParseArgs_BackendFlag", TestBackendParseArgs_BackendFlag},
+		{"TestBackendParseArgs_SkipPermissions", TestBackendParseArgs_SkipPermissions},
+		{"TestBackendParseBoolFlag", TestBackendParseBoolFlag},
+		{"TestBackendEnvFlagEnabled", TestBackendEnvFlagEnabled},
+		{"TestRunResolveTimeout", TestRunResolveTimeout},
+		{"TestRunIsTerminal", TestRunIsTerminal},
+		{"TestRunReadPipedTask", TestRunReadPipedTask},
+		{"TestTailBufferWrite", TestTailBufferWrite},
+		{"TestLogWriterWriteLimitsBuffer", TestLogWriterWriteLimitsBuffer},
+		{"TestLogWriterLogLine", TestLogWriterLogLine},
+		{"TestNewLogWriterDefaultMaxLen", TestNewLogWriterDefaultMaxLen},
+		{"TestNewLogWriterDefaultLimit", TestNewLogWriterDefaultLimit},
+		{"TestRunHello", TestRunHello},
+		{"TestRunGreet", TestRunGreet},
+		{"TestRunFarewell", TestRunFarewell},
+		{"TestRunFarewellEmpty", TestRunFarewellEmpty},
+
+		{"TestParallelParseConfig_Success", TestParallelParseConfig_Success},
+		{"TestParallelParseConfig_Backend", TestParallelParseConfig_Backend},
+		{"TestParallelParseConfig_InvalidFormat", TestParallelParseConfig_InvalidFormat},
+		{"TestParallelParseConfig_EmptyTasks", TestParallelParseConfig_EmptyTasks},
+		{"TestParallelParseConfig_MissingID", TestParallelParseConfig_MissingID},
+		{"TestParallelParseConfig_MissingTask", TestParallelParseConfig_MissingTask},
+		{"TestParallelParseConfig_DuplicateID", TestParallelParseConfig_DuplicateID},
+		{"TestParallelParseConfig_DelimiterFormat", TestParallelParseConfig_DelimiterFormat},
+
+		{"TestBackendSelectBackend", TestBackendSelectBackend},
+		{"TestBackendSelectBackend_Invalid", TestBackendSelectBackend_Invalid},
+		{"TestBackendSelectBackend_DefaultOnEmpty", TestBackendSelectBackend_DefaultOnEmpty},
+		{"TestBackendBuildArgs_CodexBackend", TestBackendBuildArgs_CodexBackend},
+		{"TestBackendBuildArgs_ClaudeBackend", TestBackendBuildArgs_ClaudeBackend},
+		{"TestClaudeBackendBuildArgs_OutputValidation", TestClaudeBackendBuildArgs_OutputValidation},
+		{"TestBackendBuildArgs_GeminiBackend", TestBackendBuildArgs_GeminiBackend},
+		{"TestGeminiBackendBuildArgs_OutputValidation", TestGeminiBackendBuildArgs_OutputValidation},
+		{"TestBackendNamesAndCommands", TestBackendNamesAndCommands},
+
+		{"TestBackendParseJSONStream", TestBackendParseJSONStream},
+		{"TestBackendParseJSONStream_ClaudeEvents", TestBackendParseJSONStream_ClaudeEvents},
+		{"TestBackendParseJSONStream_GeminiEvents", TestBackendParseJSONStream_GeminiEvents},
+		{"TestBackendParseJSONStreamWithWarn_InvalidLine", TestBackendParseJSONStreamWithWarn_InvalidLine},
+		{"TestBackendParseJSONStream_OnMessage", TestBackendParseJSONStream_OnMessage},
+		{"TestBackendParseJSONStream_ScannerError", TestBackendParseJSONStream_ScannerError},
+		{"TestBackendDiscardInvalidJSON", TestBackendDiscardInvalidJSON},
+		{"TestBackendDiscardInvalidJSONBuffer", TestBackendDiscardInvalidJSONBuffer},
+
+		{"TestCurrentWrapperNameFallsBackToExecutable", TestCurrentWrapperNameFallsBackToExecutable},
+		{"TestCurrentWrapperNameDetectsLegacyAliasSymlink", TestCurrentWrapperNameDetectsLegacyAliasSymlink},
+
+		{"TestIsProcessRunning", TestIsProcessRunning},
+		{"TestGetProcessStartTimeReadsProcStat", TestGetProcessStartTimeReadsProcStat},
+		{"TestGetProcessStartTimeInvalidData", TestGetProcessStartTimeInvalidData},
+		{"TestGetBootTimeParsesBtime", TestGetBootTimeParsesBtime},
+		{"TestGetBootTimeInvalidData", TestGetBootTimeInvalidData},
+
+		{"TestClaudeBuildArgs_ModesAndPermissions", TestClaudeBuildArgs_ModesAndPermissions},
+		{"TestClaudeBuildArgs_GeminiAndCodexModes", TestClaudeBuildArgs_GeminiAndCodexModes},
+		{"TestClaudeBuildArgs_BackendMetadata", TestClaudeBuildArgs_BackendMetadata},
+	}
+
+	for _, tc := range suite {
+		t.Run(tc.name, tc.fn)
+	}
 }
 
-func TestRunCleanupOldLogsKeepsCurrentProcessLog(t *testing.T) {
+func TestLoggerCleanupOldLogsKeepsCurrentProcessLog(t *testing.T) {
 	tempDir := setTempDirEnv(t, t.TempDir())
 
 	currentPID := os.Getpid()
@@ -518,7 +628,7 @@ func TestRunCleanupOldLogsKeepsCurrentProcessLog(t *testing.T) {
 	}
 }
 
-func TestIsPIDReusedScenarios(t *testing.T) {
+func TestLoggerIsPIDReusedScenarios(t *testing.T) {
 	now := time.Now()
 	tests := []struct {
 		name      string
@@ -552,7 +662,7 @@ func TestIsPIDReusedScenarios(t *testing.T) {
 	}
 }
 
-func TestIsUnsafeFileSecurityChecks(t *testing.T) {
+func TestLoggerIsUnsafeFileSecurityChecks(t *testing.T) {
 	tempDir := t.TempDir()
 	absTempDir, err := filepath.Abs(tempDir)
 	if err != nil {
@@ -601,7 +711,7 @@ func TestIsUnsafeFileSecurityChecks(t *testing.T) {
 	})
 }
 
-func TestRunLoggerPathAndRemove(t *testing.T) {
+func TestLoggerPathAndRemove(t *testing.T) {
 	tempDir := t.TempDir()
 	path := filepath.Join(tempDir, "sample.log")
 	if err := os.WriteFile(path, []byte("test"), 0o644); err != nil {
@@ -628,7 +738,19 @@ func TestRunLoggerPathAndRemove(t *testing.T) {
 	}
 }
 
-func TestRunLoggerInternalLog(t *testing.T) {
+func TestLoggerTruncateBytesCoverage(t *testing.T) {
+	if got := truncateBytes([]byte("abc"), 3); got != "abc" {
+		t.Fatalf("truncateBytes() = %q, want %q", got, "abc")
+	}
+	if got := truncateBytes([]byte("abcd"), 3); got != "abc..." {
+		t.Fatalf("truncateBytes() = %q, want %q", got, "abc...")
+	}
+	if got := truncateBytes([]byte("abcd"), -1); got != "" {
+		t.Fatalf("truncateBytes() = %q, want empty string", got)
+	}
+}
+
+func TestLoggerInternalLog(t *testing.T) {
 	logger := &Logger{
 		ch:        make(chan logEntry, 1),
 		done:      make(chan struct{}),
@@ -653,7 +775,7 @@ func TestRunLoggerInternalLog(t *testing.T) {
 	close(logger.done)
 }
 
-func TestRunParsePIDFromLog(t *testing.T) {
+func TestLoggerParsePIDFromLog(t *testing.T) {
 	hugePID := strconv.FormatInt(math.MaxInt64, 10) + "0"
 	tests := []struct {
 		name string
@@ -769,7 +891,7 @@ func (f fakeFileInfo) ModTime() time.Time { return f.modTime }
 func (f fakeFileInfo) IsDir() bool        { return false }
 func (f fakeFileInfo) Sys() interface{}   { return nil }
 
-func TestExtractRecentErrors(t *testing.T) {
+func TestLoggerExtractRecentErrors(t *testing.T) {
 	tests := []struct {
 		name       string
 		content    string
@@ -846,21 +968,21 @@ func TestExtractRecentErrors(t *testing.T) {
 	}
 }
 
-func TestExtractRecentErrorsNilLogger(t *testing.T) {
+func TestLoggerExtractRecentErrorsNilLogger(t *testing.T) {
 	var logger *Logger
 	if got := logger.ExtractRecentErrors(10); got != nil {
 		t.Fatalf("nil logger ExtractRecentErrors() should return nil, got %v", got)
 	}
 }
 
-func TestExtractRecentErrorsEmptyPath(t *testing.T) {
+func TestLoggerExtractRecentErrorsEmptyPath(t *testing.T) {
 	logger := &Logger{path: ""}
 	if got := logger.ExtractRecentErrors(10); got != nil {
 		t.Fatalf("empty path ExtractRecentErrors() should return nil, got %v", got)
 	}
 }
 
-func TestExtractRecentErrorsFileNotExist(t *testing.T) {
+func TestLoggerExtractRecentErrorsFileNotExist(t *testing.T) {
 	logger := &Logger{path: "/nonexistent/path/to/log.log"}
 	if got := logger.ExtractRecentErrors(10); got != nil {
 		t.Fatalf("nonexistent file ExtractRecentErrors() should return nil, got %v", got)

codeagent-wrapper/main_integration_test.go

@@ -426,10 +426,11 @@ ok-d`
 		t.Fatalf("expected startup banner in stderr, got:\n%s", stderrOut)
 	}
 
+	// After parallel log isolation fix, each task has its own log file
 	expectedLines := map[string]struct{}{
-		fmt.Sprintf("Task a: Log: %s", expectedLog): {},
+		fmt.Sprintf("Task a: Log: %s", filepath.Join(tempDir, fmt.Sprintf("codex-wrapper-%d-a.log", os.Getpid()))): {},
-		fmt.Sprintf("Task b: Log: %s", expectedLog): {},
+		fmt.Sprintf("Task b: Log: %s", filepath.Join(tempDir, fmt.Sprintf("codex-wrapper-%d-b.log", os.Getpid()))): {},
-		fmt.Sprintf("Task d: Log: %s", expectedLog): {},
+		fmt.Sprintf("Task d: Log: %s", filepath.Join(tempDir, fmt.Sprintf("codex-wrapper-%d-d.log", os.Getpid()))): {},
 	}
 
 	if len(taskLines) != len(expectedLines) {

codeagent-wrapper/main_test.go

@@ -41,6 +41,7 @@ func resetTestHooks() {
 	closeLogger()
 	executablePathFn = os.Executable
 	runTaskFn = runCodexTask
+	runCodexTaskFn = defaultRunCodexTaskFn
 	exitFn = os.Exit
 }