feat: add custom commands for tree view context menu (#19)

## Summary

- Add two new settings (`customCommands.directory`,
`customCommands.workspace`) for configuring external commands triggered
from the tree view context menu
- Each command supports template variables (`{name}`, `{branch}`,
`{ref}`, `{head}`, `{path}`, `{dir}`, `{worktree}`) and optional
environment variables
- Commands shown via QuickPick, spawned as fire-and-forget child
processes
- Add `{dir}` template variable for workspace items (parent directory of
workspace file)
- Add spec, update README, docs, and commands spec

## Test plan

- [x] Right-click worktree/repository → "Custom Commands..." appears in
context menu
- [x] Right-click workspace file → "Custom Commands..." appears (with
workspace commands configured)
- [x] QuickPick shows configured commands with rendered command preview
- [x] External editor (Zed) opens correctly for both directory and
workspace items
- [x] macOS GUI terminal (Ghostty via `open -a`) opens at correct
directory
- [x] Menu item hidden when no custom commands configured
- [x] Menu item hidden on prunable items
- [x] Invalid config entries skipped with log warning
- [x] 89 tests passing, lint clean, build clean

Closes #17
Related: #18 (VS Code integrated terminal mode — future enhancement)

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

---------

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

Author: VdustR

.changeset/custom-commands.md

@@ -0,0 +1,5 @@
+---
+"git-work-grove": minor
+---
+
+Add custom commands: configure external commands (e.g., open in Ghostty, Zed) triggered from the tree view context menu. Supports template variables for dynamic arguments and environment variables.

.gitignore

@@ -165,6 +165,9 @@ vite.config.ts.timestamp-*
 # VS Code extension packaging output
 *.vsix
 
+# Git worktrees (isolated workspaces)
+.worktrees/
+
 # ============================================
 # Overrides (highest priority - last wins)
 # ============================================

.vscodeignore

@@ -1,5 +1,6 @@
 .vscode/**
 .vscode-test/**
+.worktrees/**
 src/**
 node_modules/**
 .changeset/**

CLAUDE.md

@@ -25,6 +25,7 @@ Design specs live in `docs/spec/`. These are the **source of truth** for how fea
 | `docs/spec/open-behavior.md` | Open modes, URI resolution, click handling |
 | `docs/spec/open-in-terminal.md` | CWD resolution, terminal naming, prunable guard |
 | `docs/spec/empty-states.md` | Git unavailable, no repository, no worktrees messages |
+| `docs/spec/custom-commands.md` | Custom commands: settings, execution, context menu |
 
 ## The 4 Fundamental Types
 

README.md

@@ -36,6 +36,7 @@ If VS Code or GitLens ever ships proper `.code-workspace` support for worktrees,
 - **Favorites** — Pin any item (repository, worktree, workspace file) to the top with drag-and-drop reordering
 - **Current indicator** — Green icon and badge highlight the currently open item
 - **Customizable templates** — Full control over labels and descriptions for all 8 item types
+- **Custom Commands** — Define your own context menu commands with template variable support
 - **Open in Terminal** — Right-click to open a terminal at any worktree or workspace file location
 - **Prune** — Clean up stale worktree records
 - **Live updates** — FileSystemWatcher detects worktree changes automatically
@@ -62,6 +63,7 @@ Right-click any item in the tree to access:
 | **Open in Current Window** | Opens in the current VS Code window |
 | **Open in Terminal** | Opens a terminal at the item's location |
 | **Reveal in Finder** | Opens the item's location in your OS file manager |
+| **Custom Commands...** | Runs a user-defined command (when configured) |
 | **Copy Name** | Copy the item's display name to clipboard |
 | **Copy Path** | Copy the item's filesystem path to clipboard |
 
@@ -113,9 +115,35 @@ Open VS Code Settings (`Cmd+,` / `Ctrl+,`) and search for `git-work-grove`:
 | `git-work-grove.openBehavior` | `ask` \| `newWindow` \| `currentWindow` \| `terminal` | `ask` | Default action when opening a workspace |
 | `git-work-grove.workspaceFile.include` | `string[]` | `["*.code-workspace"]` | Glob patterns for workspace file scanning |
 | `git-work-grove.workspaceFile.exclude` | `string[]` | `[]` | Glob patterns to exclude from scanning |
+| `git-work-grove.customCommands.directory` | `array` | `[]` | Custom commands for repository/worktree items |
+| `git-work-grove.customCommands.workspace` | `array` | `[]` | Custom commands for workspace file items |
 | `git-work-grove.template.*` | `string` | *(varies)* | Display templates (label, description, terminalName) — see [Template Customization](https://github.com/vp-tw/vscode-extension-git-work-grove/blob/main/docs/templates.md) |
 | `git-work-grove.favorites` | `string[]` | `[]` | Ordered list of favorited item paths (managed via the UI) |
 
+### Custom Commands
+
+Define custom commands that appear in the tree view context menu. Two settings are available — one for directory items (repository/worktree), one for workspace file items:
+
+```json
+{
+  "git-work-grove.customCommands.directory": [
+    {
+      "command": ["npm", "run", "dev"],
+      "env": { "NODE_ENV": "development" },
+      "label": "Run Dev Server"
+    }
+  ],
+  "git-work-grove.customCommands.workspace": [
+    {
+      "command": ["code", "--goto", "{path}"],
+      "label": "Open in Terminal"
+    }
+  ]
+}
+```
+
+Each entry has a `label` (shown in QuickPick), a `command` array (`[bin, ...args]`), and an optional `env` object. Both `command` and `env` values support template variables (`{name}`, `{branch}`, `{ref}`, `{head}`, `{path}` — workspace items also have `{dir}` and `{worktree}`).
+
 ### Template Customization
 
 All tree item labels and descriptions are customizable. Templates support variables like `{name}`, `{branch}`, `{ref}`, fallback syntax (`{branch|detached}`), and conditional sections (`{?branch}({branch}){/branch}`).
@@ -145,6 +173,7 @@ These commands appear when right-clicking items in the tree view:
 | Open in Current Window | Open in the current VS Code window |
 | Open in Terminal | Open a terminal at the item's location |
 | Reveal in Finder | Open the item's location in your OS file manager |
+| Custom Commands... | Run a user-defined command (when configured) |
 | Copy Name | Copy the item's display name to clipboard |
 | Copy Path | Copy the item's filesystem path to clipboard |
 | Add Favorite | Pin this item to the Favorites section |
@@ -168,6 +197,7 @@ Design documents for contributors and AI-assisted development:
 - [Open Behavior](https://github.com/vp-tw/vscode-extension-git-work-grove/blob/main/docs/spec/open-behavior.md) — Open modes, URI resolution, click handling
 - [Open in Terminal](https://github.com/vp-tw/vscode-extension-git-work-grove/blob/main/docs/spec/open-in-terminal.md) — CWD resolution, terminal naming, prunable guard
 - [Empty States](https://github.com/vp-tw/vscode-extension-git-work-grove/blob/main/docs/spec/empty-states.md) — Git unavailable, no repository, no worktrees messages
+- [Custom Commands](https://github.com/vp-tw/vscode-extension-git-work-grove/blob/main/docs/spec/custom-commands.md) — Custom commands: settings, execution, context menu
 
 ## Installation