fix(plan): clarify quickstart validation guide scope (#2805)

Co-authored-by: root <kinsonnee@gmail.com>

templates/commands/plan.md

@@ -147,7 +147,14 @@ Command ends after Phase 2 planning. Report branch, IMPL_PLAN path, and generate
    - Examples: public APIs for libraries, command schemas for CLI tools, endpoints for web services, grammars for parsers, UI contracts for applications
    - Skip if project is purely internal (build scripts, one-off tools, etc.)
 
-3. **Agent context update**:
+3. **Create quickstart validation guide** → `quickstart.md`:
+   - Document runnable validation scenarios that prove the feature works end-to-end
+   - Include prerequisites, setup commands, test/run commands, and expected outcomes
+   - Use links or references to contracts and data model details instead of duplicating them
+   - Do not include full implementation code, model/service/controller bodies, migrations, or complete test suites
+   - Keep this artifact as a validation/run guide; implementation details belong in `tasks.md` and the implementation phase
+
+4. **Agent context update**:
    - Update the plan reference between the `<!-- SPECKIT START -->` and `<!-- SPECKIT END -->` markers in `__CONTEXT_FILE__` to point to the plan file created in step 1 (the IMPL_PLAN path)
 
 **Output**: data-model.md, /contracts/*, quickstart.md, updated agent context file

tests/integrations/test_integration_generic.py

@@ -185,6 +185,20 @@ class TestGenericIntegration:
         )
         assert "__CONTEXT_FILE__" not in content
 
+    def test_plan_defines_quickstart_as_validation_guide(self, tmp_path):
+        """The generated plan command should keep quickstart.md out of implementation scope."""
+        i = get_integration("generic")
+        m = IntegrationManifest("generic", tmp_path)
+        i.setup(tmp_path, m, parsed_options={"commands_dir": ".custom/cmds"})
+        plan_file = tmp_path / ".custom" / "cmds" / "speckit.plan.md"
+        assert plan_file.exists()
+        content = plan_file.read_text(encoding="utf-8")
+
+        assert "Create quickstart validation guide" in content
+        assert "runnable validation scenarios" in content
+        assert "Do not include full implementation code" in content
+        assert "implementation details belong in `tasks.md` and the implementation phase" in content
+
     def test_implement_loads_constitution_context(self, tmp_path):
         """The generated implement command should load constitution governance context."""
         i = get_integration("generic")