feat(rules)!: retire rulebook subscriptions and per-project suppressions (#4052)

A rule's home is its scope now: a rule in a rulebook topic is global, a rule on
a project applies to that project, and retrieval reads that directly (#4074).
A subscription had stopped changing anything a session received; a suppression
muted rules from a subscription. Operator, 2026-09-15: "we have global and
project scoped rules, we don't need the subscriptions now."

What goes, whole (rule 22):
- Migration 0101 drops project_rulebook_subscriptions, project_rule_suppressions
  and project_topic_suppressions, and strips subscribe_rulebooks (and 394's
  leftover exclude_always_on_rulebooks) from stored inception choices.
- Service, MCP and REST: subscribe/unsubscribe and the four suppress/unsuppress
  operations. The Subscribers checklist, the subscribe chips, the skip buttons
  and the Suppressed section in the rules UI.
- Inception asks two questions (design system, seed Systems). create_project and
  decide_project_inception lose subscribe_rulebooks.
- Backup v15 stops exporting the three sections; older archives still restore,
  the keys simply unread. Trash no longer hard-deletes suppression rows.

What changes meaning:
- get_applicable_rules is a project's LISTING: its own rules, plus the global
  rules tagged to an area it works in. Untagged global rules apply everywhere
  and arrive by retrieval, so they are not listed. A co_surfaces partner on a
  different project is not dragged in.
- list_rules(project_id) lists that project's own rules.
- rules_payload drops subscribed_rulebooks and suppressed_*; the handshake's
  brief form is project_rules alone.
- using-scribe's "Where a new rule goes" and inception sections, tool
  docstrings and docs say global vs project. Plugin 2026.09.15.1620.

Milestone 414 step 2.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

src/scribe/mcp/tools/projects.py

@@ -66,7 +66,7 @@ async def enter_project(project_id: int) -> dict:
         project_id: The project to enter.
 
     Returns a dict with keys: project, milestone_summary, open_tasks, systems,
-    design_system, project_rules, subscribed_rulebooks, pattern_coverage —
+    design_system, project_rules, pattern_coverage —
     plus milestone_summary_omitted, inception and systems_bootstrap, each
     present only when it applies (see below).
 
@@ -83,11 +83,12 @@ async def enter_project(project_id: int) -> dict:
     with or without a milestone. A work-log counts as touching its task. Each
     names its milestone. list_tasks has the rest.
 
-    `project_rules` lists the project's own rules by id and title, and
-    `subscribed_rulebooks` the rulebooks it draws on. A rule reaches you in
-    full when your work matches it; get_rule(id) reads one, and
-    search(content_type="rule") asks whether one covers what you are about
-    to do.
+    `project_rules` lists the project's own rules by id and title. Global
+    rules (the ones in rulebooks) apply here too and are not listed. Any rule
+    reaches you in full when your work matches it — a global one or one of
+    this project's, never another project's; get_rule(id) reads one, and
+    search(content_type="rule", project_id=...) asks whether one covers what
+    you are about to do.
 
     `pattern_coverage` (usually null) is the shape-accounting line — how many
     of the bound repo's extracted shapes carry a classification against canon
@@ -109,7 +110,7 @@ async def enter_project(project_id: int) -> dict:
 
     `inception` (milestone 297) appears ONLY when the project is yours and
     nobody has decided what it inherits: it carries the current defaults
-    (the rulebooks it could subscribe to, design system, Systems), what to ask the
+    (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.
 
@@ -178,8 +179,7 @@ async def enter_project(project_id: int) -> dict:
         )
 
     # The inception ask (milestone 297): a project nobody has decided on
-    # inherits nothing, silently — no rulebook subscriptions, no design system,
-    # no Systems. Owner-only (deciding is the owner's), and only until a
+    # inherits nothing, silently — 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):
@@ -268,8 +268,9 @@ async def get_project(project_id: int) -> dict:
 
     Returns full project fields, a milestone_summary list (every milestone,
     with description and progress but no plan body; get_milestone reads a
-    plan), and the rulebook-applicable_rules / subscribed_rulebooks pair the
-    assistant should consult when working on this project.
+    plan), the project's own rules (project_rules), and applicable_rules: the
+    global rules tagged to an area this project works in. Every other global
+    rule applies too and arrives by retrieval when the work matches it.
     """
     uid = current_user_id()
     project = await projects_svc.get_project(uid, project_id)
@@ -285,18 +286,14 @@ async def get_project(project_id: int) -> dict:
     return data
 
 
-def _inception_choices(
-    subscribe_rulebooks, design_system_id, seed_systems,
-) -> dict | None:
+def _inception_choices(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 (subscribe_rulebooks is None
-            and not design_system_id and seed_systems is None):
+    if not design_system_id and seed_systems is None:
         return None
     return {
-        "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),
     }
@@ -308,18 +305,18 @@ async def create_project(
     goal: str = "",
     status: str = "active",
     color: str = "",
-    subscribe_rulebooks: list[int] | None = None,
     design_system_id: int = 0,
     seed_systems: bool | None = None,
 ) -> dict:
     """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
+    before calling, ask the operator the two inception questions and pass
+    the answers; a project created without either is UNDECIDED and
     enter_project will ask until decide_project_inception records it.
-    Defaults if nobody decides: no rulebook subscriptions, no design system,
-    no Systems.
+    Defaults if nobody decides: no design system, no Systems. Rules are not
+    an inception question: global rules (in rulebooks) apply to every
+    project, and a project's own rules are written with create_project_rule.
 
     Args:
         title: Project name (required).
@@ -327,10 +324,6 @@ 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").
-        subscribe_rulebooks: rulebook ids this project opts into.
-            Subscription is the only way a rulebook binds a project, so a
-            rulebook left out simply does not apply. list_rulebooks shows
-            which exist.
         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,
@@ -346,9 +339,7 @@ async def create_project(
         color=color or None,
     )
     data = project.to_dict()
-    choices = _inception_choices(
-        subscribe_rulebooks, design_system_id, seed_systems,
-    )
+    choices = _inception_choices(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"]
@@ -364,7 +355,6 @@ async def create_project(
 
 async def decide_project_inception(
     project_id: int,
-    subscribe_rulebooks: list[int] | None = None,
     design_system_id: int = 0,
     seed_systems: bool | None = None,
 ) -> dict:
@@ -372,22 +362,17 @@ async def decide_project_inception(
     or re-decide later (milestone 297).
 
     Owner-only. Applies the effects through the ordinary tools' paths —
-    subscribe_project_to_rulebook,
-    set_project_design_system, the standard Systems seed — and writes the
+    set_project_design_system and 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 subscriptions (use
-    unsubscribe_project_from_rulebook to undo one), replaces the design
-    system, and never re-seeds Systems a project already has.
+    the project has the design and Systems it has. Re-deciding replaces the
+    design system and never re-seeds Systems a project already has.
 
     Args: as create_project's inception args. Passing nothing records a
-    decision to take nothing (no subscriptions, no design system, no seed) —
-    a valid answer, stated.
+    decision to take nothing (no design system, no seed) — a valid answer,
+    stated.
     """
     uid = current_user_id()
-    choices = _inception_choices(
-        subscribe_rulebooks, design_system_id, seed_systems,
-    ) or {}
+    choices = _inception_choices(design_system_id, seed_systems) or {}
     decided = await inception_svc.decide(uid, project_id, choices=choices, via="mcp")
     return {"project_id": project_id, **decided}