Generate randomized worktree names when omitted

README.md

@@ -88,7 +88,7 @@ See [Commands Reference](docs/commands.md) for full documentation.
 - `stack prune` - Clean up branches with merged PRs
 - `stack rename <new-name>` - Rename branch preserving stack relationships
 - `stack parent <new-parent>` - Change the parent of the current branch
-- `stack worktree <branch-name>` - Create a worktree for a branch
+- `stack worktree [branch-name]` - Create a worktree, generating a randomized branch name when omitted
 
 ## Configuration
 

cmd/worktree.go

@@ -1,6 +1,8 @@
 package cmd
 
 import (
+	"crypto/rand"
+	"encoding/hex"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -18,20 +20,24 @@ var worktreePruneAll bool
 var worktreeList bool
 
 var worktreeCmd = &cobra.Command{
-	Use:   "worktree <branch-name> [base-branch]",
+	Use:   "worktree [branch-name] [base-branch]",
 	Short: "Create a worktree in the configured worktrees directory",
-	Long: `Create a git worktree in the configured worktrees directory for the specified branch.
+	Long: `Create a git worktree in the configured worktrees directory.
 
 If the branch exists locally or on the remote, it will be used.
 If the branch doesn't exist, a new branch will be created from the current branch
 (or from base-branch if specified) and stack tracking will be set up automatically.
+If no branch name is specified, a randomized branch name will be generated.
 Use --list to show worktrees for this repository, or --list --all for all repos.
 Use --prune to clean up worktrees for branches with merged PRs.
 Use --prune --all to remove all worktrees for this repository.
 
 By default, worktrees are created under ~/.stack/worktrees/<reponame>.
 You can change this with: git config stack.worktreesDir <path> (or use 'stack config set')`,
-	Example: `  # Create worktree for new branch (from current branch, with stack tracking)
+	Example: `  # Create a worktree with a randomized branch name
+  stack worktree
+
+  # Create worktree for new branch (from current branch, with stack tracking)
   stack worktree my-feature
 
   # Create worktree from a fresh main branch
@@ -55,6 +61,9 @@ You can change this with: git config stack.worktreesDir <path> (or use 'stack co
   # Preview without executing
   stack worktree my-feature --dry-run`,
 	Args: func(cmd *cobra.Command, args []string) error {
+		if worktreePruneAll && !worktreeList && !worktreePrune {
+			return fmt.Errorf("--all requires --list or --prune")
+		}
 		if worktreeList {
 			if len(args) > 0 {
 				return fmt.Errorf("--list does not take arguments")
@@ -67,8 +76,8 @@ You can change this with: git config stack.worktreesDir <path> (or use 'stack co
 			}
 			return nil
 		}
-		if len(args) < 1 || len(args) > 2 {
-			return fmt.Errorf("requires 1 or 2 arguments: branch name [base-branch]")
+		if len(args) > 2 {
+			return fmt.Errorf("accepts at most 2 arguments: branch name [base-branch]")
 		}
 		return nil
 	},
@@ -83,11 +92,23 @@ You can change this with: git config stack.worktreesDir <path> (or use 'stack co
 		} else if worktreePrune {
 			err = runWorktreePrune(gitClient, githubClient)
 		} else {
+			branchName := ""
+			if len(args) > 0 {
+				branchName = args[0]
+			}
 			var baseBranch string
 			if len(args) > 1 {
 				baseBranch = args[1]
 			}
-			err = runWorktree(gitClient, githubClient, args[0], baseBranch)
+			if branchName == "" {
+				branchName, err = generateRandomWorktreeName()
+				if err == nil {
+					fmt.Printf("Generated branch name %s\n", ui.Branch(branchName))
+				}
+			}
+			if err == nil {
+				err = runWorktree(gitClient, githubClient, branchName, baseBranch)
+			}
 		}
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
@@ -96,6 +117,14 @@ You can change this with: git config stack.worktreesDir <path> (or use 'stack co
 	},
 }
 
+func generateRandomWorktreeName() (string, error) {
+	randomBytes := make([]byte, 8)
+	if _, err := rand.Read(randomBytes); err != nil {
+		return "", fmt.Errorf("failed to generate random worktree name: %w", err)
+	}
+	return "worktree-" + hex.EncodeToString(randomBytes), nil
+}
+
 func init() {
 	worktreeCmd.Flags().BoolVarP(&worktreeList, "list", "l", false, "List all worktrees for this repository")
 	worktreeCmd.Flags().BoolVar(&worktreePrune, "prune", false, "Remove worktrees for branches with merged PRs")

cmd/worktree_test.go

@@ -0,0 +1,43 @@
+package cmd
+
+import (
+	"regexp"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGenerateRandomWorktreeName(t *testing.T) {
+	first, err := generateRandomWorktreeName()
+	require.NoError(t, err)
+	second, err := generateRandomWorktreeName()
+	require.NoError(t, err)
+
+	assert.Regexp(t, regexp.MustCompile(`^worktree-[0-9a-f]{16}$`), first)
+	assert.Regexp(t, regexp.MustCompile(`^worktree-[0-9a-f]{16}$`), second)
+	assert.NotEqual(t, first, second)
+}
+
+func TestWorktreeArgs(t *testing.T) {
+	originalList := worktreeList
+	originalPrune := worktreePrune
+	originalAll := worktreePruneAll
+	t.Cleanup(func() {
+		worktreeList = originalList
+		worktreePrune = originalPrune
+		worktreePruneAll = originalAll
+	})
+
+	worktreeList = false
+	worktreePrune = false
+	worktreePruneAll = false
+
+	assert.NoError(t, worktreeCmd.Args(worktreeCmd, nil))
+	assert.NoError(t, worktreeCmd.Args(worktreeCmd, []string{"feature"}))
+	assert.NoError(t, worktreeCmd.Args(worktreeCmd, []string{"feature", "main"}))
+	assert.Error(t, worktreeCmd.Args(worktreeCmd, []string{"feature", "main", "extra"}))
+
+	worktreePruneAll = true
+	assert.EqualError(t, worktreeCmd.Args(worktreeCmd, nil), "--all requires --list or --prune")
+}

decision-log.md

@@ -2,6 +2,14 @@
 
 Architectural and design decisions for Stackinator.
 
+## 2026-08-17 — Generate a randomized worktree when no branch is provided
+
+**Decision**: Allow `stack worktree` with no arguments to create a new branch and worktree using a randomized `worktree-<16 hex characters>` name.
+
+**Context**: Creating a disposable worktree required inventing and typing a branch name even when the name itself was unimportant.
+
+**Resolution**: Made the branch-name argument optional. No-argument invocation generates the name with the operating system's cryptographic random source, then follows the existing new-branch worktree flow so the current branch is recorded as its stack parent. Explicit branch names and worktree management flags retain their existing behavior.
+
 ## 2026-08-12 — Bound and separate sync network operations
 
 **Decision**: Give git fetches a five-minute timeout and GitHub CLI operations a 30-second timeout. Display fetch and PR loading as separate sync progress steps, and propagate PR lookup failures.

docs/commands.md

@@ -109,9 +109,9 @@ stack rename feature-improved-name
 stack rename feature-improved-name --dry-run
 ```
 
-## `stack worktree <branch-name> [base-branch]`
+## `stack worktree [branch-name] [base-branch]`
 
-Create a git worktree in the configured worktrees directory for the specified branch.
+Create a git worktree in the configured worktrees directory. With no arguments, Stackinator generates a randomized branch name such as `worktree-a1b2c3d4e5f60718` and creates it from the current branch.
 
 If the branch exists locally or on the remote, it will be used. If the branch doesn't exist, a new branch will be created from the current branch (or from base-branch if specified) and stack tracking will be set up automatically.
 
@@ -137,6 +137,9 @@ Interactively choose where worktrees are created for this repo:
 - `./.worktrees` (project-local)
 
 ```bash
+# Create a worktree with a randomized branch name
+stack worktree
+
 # Create worktree for new branch (from current branch, with stack tracking)
 stack worktree my-feature