feat(systems): evidence-carrying bootstrap ask for mature zero-Systems projects (#2683)

The generic zero-state systems_hint never converts: identical on every
record, maximal in scope, asked at wrap-up time — Minstrel reached 282
records with zero Systems while vocabularied projects grew organically.
What converts is the project's own evidence at the moment of action.

bootstrap_systems_ask (mcp/tools/systems.py) fires only in a project
with >=20 records and no Systems: it names the record count and recent
titles, and asks for a concrete deliverable — propose 3-6 Systems,
confirm with the operator, create_system the set. Self-retiring: the
first System ends it everywhere. Wired at both moments the task named:
untagged_systems_hint escalates to it at write time, and enter_project
carries it as systems_bootstrap at arrival (attached only when it
applies). Young projects keep the mild question; populated vocabularies
never pay the count query.

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

src/scribe/mcp/tools/systems.py

@@ -13,8 +13,57 @@ Sentinels (match the milestone/task tool conventions):
 from __future__ import annotations
 
 from scribe.mcp._context import current_user_id
+from scribe.services import notes as notes_svc
 from scribe.services import systems as systems_svc
 
+# Below this, a project is young enough that the mild "which area is this
+# about?" question stays proportionate; at or above it, a zero-Systems project
+# has demonstrated that the question never converts (#2683 — Minstrel reached
+# 282 records without a single System) and the ask escalates.
+_BOOTSTRAP_MIN_RECORDS = 20
+_BOOTSTRAP_TITLES = 6
+
+
+async def bootstrap_systems_ask(user_id: int, project_id: int) -> str | None:
+    """The escalated vocabulary-bootstrap ask for a mature zero-Systems project.
+
+    The generic zero-state question habituates: identical on every record,
+    maximal in scope ("invent the taxonomy"), asked at wrap-up time — so
+    organic sessions skip it forever and only audit-shaped sessions ever mint
+    (#2683). What separates the nudges that convert from the prose that
+    doesn't (the duplicate gate, the prior-art "already defined in 2 files")
+    is the project's OWN evidence in the ask — so this one carries the record
+    count and the recent titles, and asks for a concrete deliverable: propose
+    a starter set, confirm, create.
+
+    Self-retiring by construction: callers only reach for it while the
+    project has zero Systems, so the first create_system ends it everywhere.
+    Returns None below the record threshold or on any failure (fail-open —
+    a hint must never break the call it rides on).
+    """
+    try:
+        recent, total = await notes_svc.list_notes(
+            user_id, project_id=project_id, sort="updated_at",
+            limit=_BOOTSTRAP_TITLES,
+        )
+    except Exception:
+        return None
+    if total < _BOOTSTRAP_MIN_RECORDS:
+        return None
+    titles = "; ".join(
+        '"' + " ".join((n.title or "").split())[:70] + '"' for n in recent
+    )
+    return (
+        f"This project has {total} records and NO Systems modelled — none of "
+        "them can be tagged to an area, so recurring problem-spots stay "
+        "invisible. Bootstrap the vocabulary now, in this session: from the "
+        f"areas the records themselves name (recent: {titles}), propose 3-6 "
+        "Systems to the operator, create_system each confirmed one with a "
+        "one-paragraph charter, then tag this record (system_ids=[...]). "
+        "This ask repeats until the first System exists; answering it once "
+        "retires it for every future record."
+    )
+
 
 async def untagged_systems_hint(user_id: int, project_id: int) -> str | None:
     """The Systems question, for an untagged project record.
@@ -26,6 +75,10 @@ async def untagged_systems_hint(user_id: int, project_id: int) -> str | None:
     vocabulary is not an exemption — it is the question at its most urgent
     (#2562, #2569). Instruction prose alone demonstrably doesn't fire at write
     time; in-band behavior (the duplicate gate) does.
+
+    In a MATURE zero-Systems project the question escalates to the bootstrap
+    ask instead (#2683): the mild form demonstrably never converts there, and
+    an evidence-carrying, deliverable-shaped ask is the form that does.
     """
     # Fail-open like the dedup gate: a hint must never break the call.
     try:
@@ -37,6 +90,9 @@ async def untagged_systems_hint(user_id: int, project_id: int) -> str | None:
             f"#{s.id} {s.name}" for s in systems
         ) + "."
     else:
+        ask = await bootstrap_systems_ask(user_id, project_id)
+        if ask:
+            return ask
         vocab = "This project has no Systems yet."
     return (
         "This record is untagged — which area(s) of the project is it about? "