feat: add multi-project workspace commands (#1241)

Three new commands for managing isolated GSD workspaces:
- /gsd:new-workspace — create workspace with repo worktrees/clones
- /gsd:list-workspaces — scan ~/gsd-workspaces/ for active workspaces
- /gsd:remove-workspace — clean up workspace and git worktrees

Supports both multi-repo orchestration (subset of repos from a parent
directory) and feature branch isolation (worktree of current repo with
independent .planning/).

Includes init functions, command routing, workflows, 24 tests, and
user documentation.

Closes #1241

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/COMMANDS.md

@@ -32,6 +32,62 @@ Initialize a new project with deep context gathering.
 
 ---
 
+### `/gsd:new-workspace`
+
+Create an isolated workspace with repo copies and independent `.planning/` directory.
+
+| Flag | Description |
+|------|-------------|
+| `--name <name>` | Workspace name (required) |
+| `--repos repo1,repo2` | Comma-separated repo paths or names |
+| `--path /target` | Target directory (default: `~/gsd-workspaces/<name>`) |
+| `--strategy worktree\|clone` | Copy strategy (default: `worktree`) |
+| `--branch <name>` | Branch to checkout (default: `workspace/<name>`) |
+| `--auto` | Skip interactive questions |
+
+**Use cases:**
+- Multi-repo: work on a subset of repos with isolated GSD state
+- Feature isolation: `--repos .` creates a worktree of the current repo
+
+**Produces:** `WORKSPACE.md`, `.planning/`, repo copies (worktrees or clones)
+
+```bash
+/gsd:new-workspace --name feature-b --repos hr-ui,ZeymoAPI
+/gsd:new-workspace --name feature-b --repos . --strategy worktree  # Same-repo isolation
+/gsd:new-workspace --name spike --repos api,web --strategy clone   # Full clones
+```
+
+---
+
+### `/gsd:list-workspaces`
+
+List active GSD workspaces and their status.
+
+**Scans:** `~/gsd-workspaces/` for `WORKSPACE.md` manifests
+**Shows:** Name, repo count, strategy, GSD project status
+
+```bash
+/gsd:list-workspaces
+```
+
+---
+
+### `/gsd:remove-workspace`
+
+Remove a workspace and clean up git worktrees.
+
+| Argument | Required | Description |
+|----------|----------|-------------|
+| `<name>` | Yes | Workspace name to remove |
+
+**Safety:** Refuses removal if any repo has uncommitted changes. Requires name confirmation.
+
+```bash
+/gsd:remove-workspace feature-b
+```
+
+---
+
 ### `/gsd:discuss-phase`
 
 Capture implementation decisions before planning.

docs/USER-GUIDE.md

@@ -625,6 +625,31 @@ claude --dangerously-skip-permissions
 /gsd:remove-phase 7         # Descope phase 7 and renumber
 ```
 
+### Multi-Project Workspaces
+
+Work on multiple repos or features in parallel with isolated GSD state.
+
+```bash
+# Create a workspace with repos from your monorepo
+/gsd:new-workspace --name feature-b --repos hr-ui,ZeymoAPI
+
+# Feature branch isolation — worktree of current repo with its own .planning/
+/gsd:new-workspace --name feature-b --repos .
+
+# Then cd into the workspace and initialize GSD
+cd ~/gsd-workspaces/feature-b
+/gsd:new-project
+
+# List and manage workspaces
+/gsd:list-workspaces
+/gsd:remove-workspace feature-b
+```
+
+Each workspace gets:
+- Its own `.planning/` directory (fully independent from source repos)
+- Git worktrees (default) or clones of specified repos
+- A `WORKSPACE.md` manifest tracking member repos
+
 ---
 
 ## Troubleshooting