feat: project init with config package and root command

Go module, cobra root command, config resolution (CTASK_ROOT, CTASK_AGENT, EnvVars) with tests.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/config/config.go

@@ -0,0 +1,48 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// ResolveRoot returns the absolute workspace root path.
+// Reads CTASK_ROOT env var, falls back to ~/ai-workspaces (or %USERPROFILE%\ai-workspaces on Windows).
+func ResolveRoot() string {
+	root := os.Getenv("CTASK_ROOT")
+	if root == "" {
+		home, _ := os.UserHomeDir()
+		return filepath.Join(home, "ai-workspaces")
+	}
+	// Expand leading tilde
+	if strings.HasPrefix(root, "~/") || root == "~" {
+		home, _ := os.UserHomeDir()
+		root = filepath.Join(home, root[2:])
+	}
+	abs, err := filepath.Abs(root)
+	if err != nil {
+		return root
+	}
+	return abs
+}
+
+// ResolveAgent returns the agent command.
+// Reads CTASK_AGENT env var, falls back to "claude".
+func ResolveAgent() string {
+	agent := os.Getenv("CTASK_AGENT")
+	if agent == "" {
+		return "claude"
+	}
+	return agent
+}
+
+// EnvVars returns the environment variables to export into child sessions.
+func EnvVars(slug, mode, root, workspace, category string) map[string]string {
+	return map[string]string{
+		"CTASK_TASK":      slug,
+		"CTASK_MODE":      mode,
+		"CTASK_ROOT":      root,
+		"CTASK_WORKSPACE": workspace,
+		"CTASK_CATEGORY":  category,
+	}
+}

internal/config/config_test.go

@@ -0,0 +1,85 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+func TestDefaultRoot(t *testing.T) {
+	os.Unsetenv("CTASK_ROOT")
+	root := ResolveRoot()
+	home, _ := os.UserHomeDir()
+	expected := filepath.Join(home, "ai-workspaces")
+	if root != expected {
+		t.Errorf("expected %q, got %q", expected, root)
+	}
+}
+
+func TestCustomRoot(t *testing.T) {
+	dir := t.TempDir()
+	os.Setenv("CTASK_ROOT", dir)
+	defer os.Unsetenv("CTASK_ROOT")
+	root := ResolveRoot()
+	if root != dir {
+		t.Errorf("expected %q, got %q", dir, root)
+	}
+}
+
+func TestRootResolvesRelative(t *testing.T) {
+	os.Setenv("CTASK_ROOT", "relative/path")
+	defer os.Unsetenv("CTASK_ROOT")
+	root := ResolveRoot()
+	if !filepath.IsAbs(root) {
+		t.Errorf("expected absolute path, got %q", root)
+	}
+}
+
+func TestDefaultAgent(t *testing.T) {
+	os.Unsetenv("CTASK_AGENT")
+	agent := ResolveAgent()
+	if agent != "claude" {
+		t.Errorf("expected \"claude\", got %q", agent)
+	}
+}
+
+func TestCustomAgent(t *testing.T) {
+	os.Setenv("CTASK_AGENT", "aider")
+	defer os.Unsetenv("CTASK_AGENT")
+	agent := ResolveAgent()
+	if agent != "aider" {
+		t.Errorf("expected \"aider\", got %q", agent)
+	}
+}
+
+func TestRootResolvesTilde(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("tilde expansion not typical on Windows")
+	}
+	os.Setenv("CTASK_ROOT", "~/my-workspaces")
+	defer os.Unsetenv("CTASK_ROOT")
+	root := ResolveRoot()
+	if root[0] == '~' {
+		t.Errorf("tilde not expanded: %q", root)
+	}
+	if !filepath.IsAbs(root) {
+		t.Errorf("expected absolute path, got %q", root)
+	}
+}
+
+func TestEnvVars(t *testing.T) {
+	vars := EnvVars("my-slug", "local", "/abs/root", "/abs/root/cat/ws", "general")
+	expected := map[string]string{
+		"CTASK_TASK":      "my-slug",
+		"CTASK_MODE":      "local",
+		"CTASK_ROOT":      "/abs/root",
+		"CTASK_WORKSPACE": "/abs/root/cat/ws",
+		"CTASK_CATEGORY":  "general",
+	}
+	for k, v := range expected {
+		if vars[k] != v {
+			t.Errorf("env %s: expected %q, got %q", k, v, vars[k])
+		}
+	}
+}