feat: add session resume support and improve output format

- Support session_id in parallel task config for resuming failed tasks
- Change output format from JSON to human-readable text
- Add helper functions (hello, greet, farewell) with tests
- Clean up code formatting

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

codex-wrapper/main.go

@@ -26,7 +26,6 @@ const (
 	stdinSpecialChars = "\n\\\"'`$"
 )
 
-
 // Test hooks for dependency injection
 var (
 	stdinReader      io.Reader = os.Stdin
@@ -58,8 +57,8 @@ type TaskSpec struct {
 	Task         string   `json:"task"`
 	WorkDir      string   `json:"workdir,omitempty"`
 	Dependencies []string `json:"dependencies,omitempty"`
+	SessionID    string   `json:"session_id,omitempty"`
 	Mode         string   `json:"-"`
-	SessionID    string   `json:"-"`
 	UseStdin     bool     `json:"-"`
 }
 
@@ -72,7 +71,6 @@ type TaskResult struct {
 	Error     string `json:"error"`
 }
 
-
 func parseParallelConfig(data []byte) (*ParallelConfig, error) {
 	trimmed := bytes.TrimSpace(data)
 	if len(trimmed) == 0 {
@@ -115,6 +113,9 @@ func parseParallelConfig(data []byte) (*ParallelConfig, error) {
 				task.ID = value
 			case "workdir":
 				task.WorkDir = value
+			case "session_id":
+				task.SessionID = value
+				task.Mode = "resume"
 			case "dependencies":
 				for _, dep := range strings.Split(value, ",") {
 					dep = strings.TrimSpace(dep)
@@ -396,7 +397,6 @@ func run() int {
 		}
 	}
 
-
 	logInfo("Script started")
 
 	cfg, err := parseArgs()
@@ -856,8 +856,16 @@ func min(a, b int) int {
 	return b
 }
 
-func test() string {
-	return "hello $world"
+func hello() string {
+	return "hello world"
+}
+
+func greet(name string) string {
+	return "hello " + name
+}
+
+func farewell(name string) string {
+	return "goodbye " + name
 }
 
 func logInfo(msg string) {

codex-wrapper/main_test.go

@@ -624,6 +624,34 @@ func TestMin(t *testing.T) {
 	}
 }
 
+func TestHello(t *testing.T) {
+	got := hello()
+	if got != "hello world" {
+		t.Fatalf("hello() = %q, want %q", got, "hello world")
+	}
+}
+
+func TestGreet(t *testing.T) {
+	got := greet("Linus")
+	if got != "hello Linus" {
+		t.Fatalf("greet() = %q, want %q", got, "hello Linus")
+	}
+}
+
+func TestFarewell(t *testing.T) {
+	got := farewell("Linus")
+	if got != "goodbye Linus" {
+		t.Fatalf("farewell() = %q, want %q", got, "goodbye Linus")
+	}
+}
+
+func TestFarewellEmpty(t *testing.T) {
+	got := farewell("")
+	if got != "goodbye " {
+		t.Fatalf("farewell(\"\") = %q, want %q", got, "goodbye ")
+	}
+}
+
 func TestLogFunctions(t *testing.T) {
 	// Capture stderr
 	oldStderr := os.Stderr

skills/codex/SKILL.md

@@ -206,17 +206,36 @@ EOF
 - `id: <task-id>`: Required, unique task identifier
 - `workdir: <path>`: Optional, working directory (default: `.`)
 - `dependencies: <id1>, <id2>`: Optional, comma-separated task IDs
+- `session_id: <uuid>`: Optional, resume a previous session
 - `---CONTENT---`: Separates metadata from task content
 - Task content: Any text, code, special characters (no escaping needed)
 
-**Output**: JSON with results and summary
-```json
-{
-  "results": [
-    {"task_id": "T1", "exit_code": 0, "message": "...", "session_id": "...", "error": ""}
-  ],
-  "summary": {"total": 3, "success": 3, "failed": 0}
-}
+**Resume Failed Tasks**:
+```bash
+# Use session_id from previous output to resume
+codex-wrapper --parallel - <<'EOF'
+---TASK---
+id: T2
+session_id: 019xxx-previous-session-id
+---CONTENT---
+fix the previous error and retry
+EOF
+```
+
+**Output**: Human-readable text format
+```
+=== Parallel Execution Summary ===
+Total: 3 | Success: 2 | Failed: 1
+
+--- Task: T1 ---
+Status: SUCCESS
+Session: 019xxx
+
+Task output message...
+
+--- Task: T2 ---
+Status: FAILED (exit code 1)
+Error: some error message
 ```
 
 **Features**: