fix(mcp): list tools return rows that say what a record is, not what it says (#4061)

list_tasks returned every row's to_dict(), body included: a project's todo list
came to 93-165k characters, past what an MCP client accepts inline, so the list
arrived as a file to page through (the #4045 failure, one call over).

- notes.brief_row: id, title, type, project, tags, updated_at; for tasks,
  status, kind, priority, milestone id and title; description, parent and due
  date only when set.
- milestones.titles_for: one query for the milestone titles a page of rows
  names.
- Brief rows on list_tasks, list_notes, get_milestone's steps, get_system and
  list_system_records. get_task / get_note / get_snippet read a record in full,
  and each docstring says so.
- tests/test_list_rows_brief.py pins the ceiling: 100 rows of ~5k-character
  step plans stay under 40k characters.

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

src/scribe/services/notes.py

@@ -7,6 +7,7 @@ from sqlalchemy import func, or_, select, text
 
 from scribe.models import async_session
 from scribe.models.note import Note, TaskKind, TaskPriority, TaskStatus
+from scribe.models.base import iso
 
 logger = logging.getLogger(__name__)
 
@@ -1057,3 +1058,40 @@ async def get_note_for_user(
     async with async_session() as session:
         note = await session.get(Note, note_id)
     return (note, perm) if note else None
+
+
+# What a LISTING row carries (#4061): what the record is and where it sits,
+# never what it says. list_tasks once returned every row's to_dict(), body
+# included, and a project's todo list came to 93-165k characters, past what an
+# MCP client accepts inline, so the list arrived as a file to page through. The
+# same failure #4045 fixed for enter_project, one call over. get_task / get_note
+# read a record in full; a list is for choosing which one to open.
+#
+# A field most rows leave empty (a one-line description, a parent, a due date)
+# is attached only when set: a hundred rows of `null` are a hundred chances to
+# learn to skip the key (#2483), and the bytes are the thing being cut.
+def brief_row(note: Note, milestone_titles: dict[int, str] | None = None) -> dict:
+    row = {
+        "id": note.id,
+        "title": note.title,
+        "note_type": note.note_type or "note",
+        "project_id": note.project_id,
+        "tags": note.tags or [],
+        "updated_at": iso(note.updated_at),
+    }
+    if note.description:
+        row["description"] = note.description
+    if note.is_task:
+        row.update({
+            "status": note.status,
+            "task_kind": note.task_kind,
+            "priority": note.priority,
+            "milestone_id": note.milestone_id,
+        })
+        if milestone_titles is not None and note.milestone_id:
+            row["milestone_title"] = milestone_titles.get(note.milestone_id)
+        if note.parent_id:
+            row["parent_id"] = note.parent_id
+        if note.due_date:
+            row["due_date"] = iso(note.due_date)
+    return row