feat(inception): the doors — create_project/decide_project_inception take the decision, enter_project asks until decided, REST inception endpoints, _INSTRUCTIONS (#2882, milestone 297 step 4)

- MCP create_project(..., exclude_always_on_rulebooks, subscribe_rulebooks,
  design_system_id (0 unstated / -1 none / n), seed_systems): any inception
  arg → inception.decide(via="mcp") after the create; none → undecided with
  an inception_hint. New decide_project_inception(project_id, …) records or
  re-records; nothing given = an inherit-all decision, stated.
- enter_project carries `inception` ONLY for the caller's own, undecided
  project: inception_ask() = the project's current defaults + what to ask the
  operator once + the exact call (the #2683 ask shape). Absent otherwise.
- REST: POST /api/projects accepts `inception` (validated before the create);
  POST /api/projects/<id>/inception decides/re-decides; GET …/inception/defaults
  is the card's payload; GET project already carries inception via to_dict.
- _INSTRUCTIONS: ORIENT names the ask; START a project names the questions —
  never create a project bare by default (product behaviour, P#119).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_mcp_tool_projects.py

@@ -391,3 +391,81 @@ def test_enter_project_registered_in_register():
 
     register(mcp)
     assert "enter_project" in mcp.names
+
+
+# --- milestone 297: the inception doors ---------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_create_project_without_inception_args_stays_undecided():
+    p = fake_project(id=5, title="P", inception=None)
+    with patch("scribe.mcp.tools.projects.projects_svc.create_project", AsyncMock(return_value=p)), \
+         patch("scribe.mcp.tools.projects.inception_svc.decide", AsyncMock()) as decide:
+        out = await create_project(title="P")
+    decide.assert_not_awaited()
+    assert "inception_hint" in out and "inception_effects" not in out
+
+
+@pytest.mark.asyncio
+async def test_create_project_with_inception_args_decides_via_mcp():
+    p = fake_project(id=5, title="P", inception=None)
+    decided = {"inception": {"via": "mcp", "choices": {}}, "effects": {"systems_seeded": []}}
+    with patch("scribe.mcp.tools.projects.projects_svc.create_project", AsyncMock(return_value=p)), \
+         patch("scribe.mcp.tools.projects.inception_svc.decide", AsyncMock(return_value=decided)) as decide:
+        out = await create_project(title="P", exclude_always_on_rulebooks=[1], design_system_id=-1, seed_systems=True)
+    kw = decide.await_args.kwargs
+    assert decide.await_args.args[1] == 5 and kw["via"] == "mcp"
+    assert kw["choices"] == {"exclude_always_on_rulebooks": [1], "subscribe_rulebooks": [],
+                             "design_system_id": None, "seed_systems": True}
+    assert out["inception"]["via"] == "mcp" and "inception_effects" in out
+
+
+@pytest.mark.asyncio
+async def test_decide_project_inception_tool_records_an_inherit_all_decision_when_given_nothing():
+    from scribe.mcp.tools.projects import decide_project_inception
+    decided = {"inception": {"via": "mcp"}, "effects": {}}
+    with patch("scribe.mcp.tools.projects.inception_svc.decide", AsyncMock(return_value=decided)) as decide:
+        out = await decide_project_inception(project_id=5)
+    assert decide.await_args.kwargs["choices"] == {}
+    assert out["project_id"] == 5 and out["inception"]["via"] == "mcp"
+
+
+@pytest.mark.asyncio
+async def test_enter_project_carries_the_inception_ask_only_for_an_undecided_own_project():
+    applicable = {"rules": [], "project_rules": [], "truncated": False,
+                  "subscribed_rulebooks": [], "excluded_always_on": []}
+    ask = {"defaults": {}, "ask": "decide", "call": "decide_project_inception(...)"}
+
+    async def run(project):
+        with patch("scribe.mcp.tools.projects.projects_svc.get_project", AsyncMock(return_value=project)), \
+             patch("scribe.mcp.tools.projects.rulebooks_svc.get_applicable_rules", AsyncMock(return_value=applicable)), \
+             patch("scribe.mcp.tools.projects.milestones_svc.get_project_milestone_summary", AsyncMock(return_value=[])), \
+             patch("scribe.mcp.tools.projects.notes_svc.list_notes", AsyncMock(side_effect=[([], 0), ([], 0)])), \
+             patch("scribe.mcp.tools.projects.systems_svc.list_systems", AsyncMock(return_value=[])), \
+             patch("scribe.mcp.tools.projects.systems_tools.bootstrap_systems_ask", AsyncMock(return_value=None)), \
+             patch("scribe.mcp.tools.projects.inception_svc.inception_ask", AsyncMock(return_value=ask)) as asked:
+            return await enter_project(project_id=5), asked
+
+    # Own + undecided → the ask rides along.
+    out, asked = await run(fake_project(id=5, title="P", user_id=7, inception=None))
+    assert out["inception"] == ask and asked.await_count == 1
+    # Decided → absent, and the ask is not even built.
+    out, asked = await run(fake_project(id=5, title="P", user_id=7, inception={"via": "legacy"}))
+    assert "inception" not in out and asked.await_count == 0
+    # Someone else's (shared) project, undecided → not this caller's to decide.
+    out, asked = await run(fake_project(id=5, title="P", user_id=8, inception=None))
+    assert "inception" not in out and asked.await_count == 0
+
+
+def test_inception_routes_and_tool_are_registered():
+    from scribe.app import create_app
+    from scribe.mcp.server import build_mcp_server
+    rules = {r.rule for r in create_app().url_map.iter_rules()}
+    assert "/api/projects/<int:project_id>/inception" in rules
+    assert "/api/projects/<int:project_id>/inception/defaults" in rules
+    mcp = build_mcp_server()
+    assert mcp._tool_manager.get_tool("decide_project_inception") is not None
+    tool = mcp._tool_manager.get_tool("create_project")
+    for name in ("exclude_always_on_rulebooks", "subscribe_rulebooks", "design_system_id", "seed_systems"):
+        assert name in tool.parameters.get("properties", {}), name
+