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>

src/scribe/mcp/tools/projects.py

@@ -20,6 +20,7 @@ from scribe.mcp._context import current_user_id
 from scribe.mcp.tools import systems as systems_tools
 from scribe.services import coverage as coverage_svc
 from scribe.services import design_systems as design_systems_svc
+from scribe.services import inception as inception_svc
 from scribe.services import milestones as milestones_svc
 from scribe.services import notes as notes_svc
 from scribe.services import projects as projects_svc
@@ -80,6 +81,12 @@ async def enter_project(project_id: int) -> dict:
     create it with create_system rather than leaving the area unmodelled. Read
     a subsystem's accumulated records with list_system_records.
 
+    `inception` (milestone 297) appears ONLY when the project is yours and
+    nobody has decided what it inherits: it carries the current defaults
+    (which always-on rulebooks bind, design system, Systems), what to ask the
+    operator — once — and the decide_project_inception call that answers it;
+    it repeats on every enter until a decision is recorded.
+
     `systems_bootstrap` appears ONLY when the project has many records and no
     Systems at all — act on it before starting other work: create_system a
     starter vocabulary from the areas the project's records name, directly
@@ -141,6 +148,14 @@ async def enter_project(project_id: int) -> dict:
             uid, project_id
         )
 
+    # The inception ask (milestone 297): a project nobody has decided on
+    # inherits its defaults silently — always-on rulebooks, no design system,
+    # no Systems. Owner-only (deciding is the owner's), and only until a
+    # decision is recorded; the key is ABSENT otherwise (#2483).
+    inception_ask = None
+    if project.user_id == uid and not inception_svc.is_decided(project):
+        inception_ask = await inception_svc.inception_ask(uid, project_id)
+
     # Probably the largest surfacing by volume, and it emitted nothing — so
     # the pulls it caused floated unattributed and the surfaced:pulled ratio
     # ran against a denominator missing its biggest contributor (#2477). An
@@ -213,6 +228,8 @@ async def enter_project(project_id: int) -> dict:
     # readers to skip it (#2483), and this one exists to be acted on.
     if systems_bootstrap:
         out["systems_bootstrap"] = systems_bootstrap
+    if inception_ask:
+        out["inception"] = inception_ask
     return out
 
 
@@ -238,14 +255,43 @@ async def get_project(project_id: int) -> dict:
     return data
 
 
+def _inception_choices(
+    exclude_always_on_rulebooks, subscribe_rulebooks, design_system_id, seed_systems,
+) -> dict | None:
+    """The tool args → an inception choices object, or None when no inception
+    arg was given at all (a bare create stays undecided and enter_project
+    asks). design_system_id: 0 = not stated, -1 = explicitly none, n = that
+    system."""
+    if (exclude_always_on_rulebooks is None and subscribe_rulebooks is None
+            and not design_system_id and seed_systems is None):
+        return None
+    return {
+        "exclude_always_on_rulebooks": list(exclude_always_on_rulebooks or []),
+        "subscribe_rulebooks": list(subscribe_rulebooks or []),
+        "design_system_id": None if design_system_id in (0, -1) else design_system_id,
+        "seed_systems": bool(seed_systems),
+    }
+
+
 async def create_project(
     title: str,
     description: str = "",
     goal: str = "",
     status: str = "active",
     color: str = "",
+    exclude_always_on_rulebooks: list[int] | None = None,
+    subscribe_rulebooks: list[int] | None = None,
+    design_system_id: int = 0,
+    seed_systems: bool | None = None,
 ) -> dict:
-    """Create a new project in Scribe.
+    """Create a new project in Scribe — and decide what it inherits.
+
+    A project's inheritance is a decision, not a default (milestone 297):
+    before calling, ask the operator the four inception questions and pass
+    the answers; a project created without any of them is UNDECIDED and
+    enter_project will ask until decide_project_inception records it.
+    Defaults if nobody decides: every always-on rulebook binds, nothing is
+    subscribed, no design system, no Systems.
 
     Args:
         title: Project name (required).
@@ -253,6 +299,14 @@ async def create_project(
         goal: The desired outcome or definition of done for the project.
         status: one of active (default), paused, completed, archived.
         color: Optional hex colour for the project card (e.g. "#6366f1").
+        exclude_always_on_rulebooks: always-on rulebook ids this project does
+            NOT inherit ([] = inherit them all). list_rulebooks shows which are
+            always_on.
+        subscribe_rulebooks: rulebook ids to subscribe (the non-always-on ones).
+        design_system_id: the design system this project's UI is built from
+            (list_design_systems); -1 = explicitly none; 0 = not stated.
+        seed_systems: true mints the standard starter Systems (CI & Release,
+            Auth & Access, …) so records can be tagged from day one.
     """
     uid = current_user_id()
     project = await projects_svc.create_project(
@@ -263,7 +317,52 @@ async def create_project(
         status=status,
         color=color or None,
     )
-    return project.to_dict()
+    data = project.to_dict()
+    choices = _inception_choices(
+        exclude_always_on_rulebooks, subscribe_rulebooks, design_system_id, seed_systems,
+    )
+    if choices is not None:
+        decided = await inception_svc.decide(uid, project.id, choices=choices, via="mcp")
+        data["inception"] = decided["inception"]
+        data["inception_effects"] = decided["effects"]
+    else:
+        data["inception_hint"] = (
+            "Undecided: this project inherits its defaults until "
+            "decide_project_inception records what it should inherit "
+            "(enter_project will ask)."
+        )
+    return data
+
+
+async def decide_project_inception(
+    project_id: int,
+    exclude_always_on_rulebooks: list[int] | None = None,
+    subscribe_rulebooks: list[int] | None = None,
+    design_system_id: int = 0,
+    seed_systems: bool | None = None,
+) -> dict:
+    """Record what a project inherits — answer enter_project's `inception` ask,
+    or re-decide later (milestone 297).
+
+    Owner-only. Applies the effects through the ordinary tools' paths —
+    exclude_always_on_rulebook, subscribe_project_to_rulebook,
+    set_project_design_system, the standard Systems seed — and writes the
+    decision on the project last, so get_project/enter_project can say why
+    the project has the rules, design and Systems it has. Re-deciding is
+    additive for exclusions/subscriptions (use include_always_on_rulebook /
+    unsubscribe_project_from_rulebook to undo one), replaces the design
+    system, and never re-seeds Systems a project already has.
+
+    Args: as create_project's inception args. Passing nothing records an
+    inherit-all decision (every always-on rulebook binds, no subscriptions,
+    no design system, no seed) — a valid answer, stated.
+    """
+    uid = current_user_id()
+    choices = _inception_choices(
+        exclude_always_on_rulebooks, subscribe_rulebooks, design_system_id, seed_systems,
+    ) or {}
+    decided = await inception_svc.decide(uid, project_id, choices=choices, via="mcp")
+    return {"project_id": project_id, **decided}
 
 
 async def update_project(
@@ -320,6 +419,6 @@ def register(mcp) -> None:
         get_project,
         create_project,
         update_project,
-        delete_project,
+        delete_project, decide_project_inception,
     ):
         mcp.tool(name=fn.__name__)(fn)