feat: add bundled lean preset with minimal workflow commands (#2161)

* feat: add bundled lean preset with minimal workflow commands

Add a lean preset that overrides the 5 core workflow commands (specify,
plan, tasks, implement, constitution) with minimal prompts that produce
exactly one artifact each — no extension hooks, no scripts, no git
branching, no templates.

Bundled preset infrastructure:
- Add _locate_bundled_preset() mirroring _locate_bundled_extension()
- Update 'specify init --preset' to try bundled -> catalog fallback
- Update 'specify preset add' to try bundled -> catalog fallback
- Add bundled guard in download_pack() for presets without download URLs
- Add lean to presets/catalog.json with 'bundled: true' marker
- Add lean to pyproject.toml force-include for wheel packaging
- Align error messages with bundled extension error pattern

Tests: 15 new tests (TestLeanPreset + TestBundledPresetLocator)

* refactor: address review — clean up unused imports, strengthen test assertions

- Remove unused MagicMock import and cache_dir setup in download test
- Assert 'bundled' and 'reinstall' in CLI error output (not just exit code)
- Mock catalog in missing-locally test for deterministic bundled error path
- Fix test versions to satisfy updated speckit_version >=0.6.0 requirement

* refactor: address review — fix constitution paths, add REINSTALL_COMMAND to presets.py

- Fix constitution path to .specify/memory/constitution.md in plan, tasks,
  implement commands (matching core command convention)
- Include REINSTALL_COMMAND in download_pack() bundled guard for consistent
  recovery instructions across bundled extensions and presets

* refactor: address review — explicit feature_directory paths, ZIP cleanup in finally

- Prefix spec.md/plan.md/tasks.md with <feature_directory>/ in plan, tasks,
  and implement commands so the agent doesn't operate on repo root by mistake
- Move ZIP unlink into finally block in init --preset path so cleanup runs
  even when install_from_zip raises (matching preset_add pattern)

* refactor: address review — replace Unicode em dashes with ASCII, fix grammar

- Replace all Unicode em dashes with ASCII hyphens in preset.yml and
  catalog.json to avoid decode errors on non-UTF-8 environments
- Fix grammar: 'store it in tasks.md' -> 'store them in tasks.md'

* refactor: address review - align task format between tasks and implement

- Remove undefined [P] marker from implement (lean uses sequential execution)
- Clarify checkbox update: 'change - [ ] to - [x]' instead of ambiguous '[X]'
- Simplify implement to execute tasks in order without parallel complexity

* refactor: address review - parse frontmatter instead of raw substring search

- Use CommandRegistrar.parse_frontmatter() to check for scripts/agent_scripts
  keys in YAML frontmatter instead of brittle 'scripts:' substring search

presets/catalog.json

@@ -1,6 +1,22 @@
 {
   "schema_version": "1.0",
-  "updated_at": "2026-03-10T00:00:00Z",
+  "updated_at": "2026-04-10T00:00:00Z",
   "catalog_url": "https://raw.githubusercontent.com/github/spec-kit/main/presets/catalog.json",
-  "presets": {}
+  "presets": {
+    "lean": {
+      "name": "Lean Workflow",
+      "id": "lean",
+      "version": "1.0.0",
+      "description": "Minimal core workflow commands - just the prompt, just the artifact",
+      "author": "github",
+      "repository": "https://github.com/github/spec-kit",
+      "bundled": true,
+      "tags": [
+        "lean",
+        "minimal",
+        "workflow",
+        "core"
+      ]
+    }
+  }
 }

presets/lean/commands/speckit.constitution.md

@@ -0,0 +1,15 @@
+---
+description: Create or update the project constitution.
+---
+
+## User Input
+
+```text
+$ARGUMENTS
+```
+
+## Outline
+
+1. Create or update the project constitution and store it in `.specify/memory/constitution.md`.
+   - Project name, guiding principles, non-negotiable rules
+   - Derive from user input and existing repo context (README, docs)

presets/lean/commands/speckit.implement.md

@@ -0,0 +1,22 @@
+---
+description: Execute the implementation plan by processing all tasks in tasks.md.
+---
+
+## User Input
+
+```text
+$ARGUMENTS
+```
+
+## Outline
+
+1. Read `.specify/feature.json` to get the feature directory path.
+
+2. **Load context**: `.specify/memory/constitution.md` and `<feature_directory>/spec.md` and `<feature_directory>/plan.md` and `<feature_directory>/tasks.md`.
+
+3. **Execute tasks** in order:
+   - Complete each task before moving to the next
+   - Mark completed tasks by changing `- [ ]` to `- [x]` in `<feature_directory>/tasks.md`
+   - Halt on failure and report the issue
+
+4. **Validate**: Verify all tasks are completed and the implementation matches the spec.

presets/lean/commands/speckit.plan.md

@@ -0,0 +1,19 @@
+---
+description: Create a plan and store it in plan.md.
+---
+
+## User Input
+
+```text
+$ARGUMENTS
+```
+
+## Outline
+
+1. Read `.specify/feature.json` to get the feature directory path.
+
+2. **Load context**: `.specify/memory/constitution.md` and `<feature_directory>/spec.md`.
+
+3. Create an implementation plan and store it in `<feature_directory>/plan.md`.
+   - Technical context: tech stack, dependencies, project structure
+   - Design decisions, architecture, file structure

presets/lean/commands/speckit.specify.md

@@ -0,0 +1,23 @@
+---
+description: Create a specification and store it in spec.md.
+---
+
+## User Input
+
+```text
+$ARGUMENTS
+```
+
+## Outline
+
+1. **Ask the user** for the feature directory path (e.g., `specs/my-feature`). Do not proceed until provided.
+
+2. Create the directory and write `.specify/feature.json`:
+   ```json
+   { "feature_directory": "<feature_directory>" }
+   ```
+
+3. Create a specification from the user input and store it in `<feature_directory>/spec.md`.
+   - Overview, functional requirements, user scenarios, success criteria
+   - Every requirement must be testable
+   - Make informed defaults for unspecified details

presets/lean/commands/speckit.tasks.md

@@ -0,0 +1,19 @@
+---
+description: Create the tasks needed for implementation and store them in tasks.md.
+---
+
+## User Input
+
+```text
+$ARGUMENTS
+```
+
+## Outline
+
+1. Read `.specify/feature.json` to get the feature directory path.
+
+2. **Load context**: `.specify/memory/constitution.md` and `<feature_directory>/spec.md` and `<feature_directory>/plan.md`.
+
+3. Create dependency-ordered implementation tasks and store them in `<feature_directory>/tasks.md`.
+   - Every task uses checklist format: `- [ ] [TaskID] Description with file path`
+   - Organized by phase: setup, foundational, user stories in priority order, polish

presets/lean/preset.yml

@@ -0,0 +1,50 @@
+schema_version: "1.0"
+
+preset:
+  id: "lean"
+  name: "Lean Workflow"
+  version: "1.0.0"
+  description: "Minimal core workflow commands - just the prompt, just the artifact"
+  author: "github"
+  repository: "https://github.com/github/spec-kit"
+  license: "MIT"
+
+requires:
+  speckit_version: ">=0.6.0"
+
+provides:
+  templates:
+    - type: "command"
+      name: "speckit.specify"
+      file: "commands/speckit.specify.md"
+      description: "Lean specify - create spec.md from a feature description"
+      replaces: "speckit.specify"
+
+    - type: "command"
+      name: "speckit.plan"
+      file: "commands/speckit.plan.md"
+      description: "Lean plan - create plan.md from the spec"
+      replaces: "speckit.plan"
+
+    - type: "command"
+      name: "speckit.tasks"
+      file: "commands/speckit.tasks.md"
+      description: "Lean tasks - create tasks.md from plan and spec"
+      replaces: "speckit.tasks"
+
+    - type: "command"
+      name: "speckit.implement"
+      file: "commands/speckit.implement.md"
+      description: "Lean implement - execute tasks from tasks.md"
+      replaces: "speckit.implement"
+
+    - type: "command"
+      name: "speckit.constitution"
+      file: "commands/speckit.constitution.md"
+      description: "Lean constitution - create or update project constitution"
+      replaces: "speckit.constitution"
+
+tags:
+  - "lean"
+  - "minimal"
+  - "workflow"