fix(mcp): project reads list milestones without their plans, and cap done ones (#4045)

enter_project returned every milestone's full plan body. On a project with 39
milestones the handshake came to ~222k characters, 168k of them bodies (110k
from done milestones). That is past what an MCP client accepts as a tool
result, so the call meant to orient a session arrived as a file to page
through. It grows with a project's history, so any long-lived project on any
install gets there.

- brief_milestone_summary (services/milestones.py) trims summary rows to the
  listing fields: id, title, description, status, order_index and progress.
  The plan is get_milestone's job. user_id, project_id and timestamps repeat
  what the caller knows.
- enter_project and get_project share one block: every open milestone plus
  the 5 most recently updated done ones, in order. milestone_summary_omitted
  is attached only when older done ones were left out, and names
  list_milestones and get_milestone.
- list_milestones lists every milestone, done included, without bodies. It is
  the call the omitted line points to, and it had the same size problem.
- The REST project summary is unchanged; the web UI reads it.

Tests: trimming, the done cap and its order, the omitted key present and
absent, get_project and list_milestones, and a size ceiling on enter_project's
milestone block for a 200-milestone history.

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

tests/test_milestone_summary_brief.py

@@ -0,0 +1,141 @@
+"""Milestone listings stay brief and bounded (#4045).
+
+enter_project once carried every milestone's full plan body. On a project with
+39 milestones that came to ~222k characters, past what an MCP client accepts
+as a tool result, so the session handshake arrived as a file to page through.
+"""
+import contextlib
+import json
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+from scribe.mcp.tools.milestones import list_milestones
+from scribe.mcp.tools.projects import enter_project, get_project
+from scribe.services.milestones import brief_milestone_summary
+from tests.helpers import fake_project
+
+
+pytestmark = pytest.mark.usefixtures("_bind_user")
+
+PLAN = "A plan paragraph long enough to matter. " * 125  # ~5k chars
+
+
+def _row(mid: int, status: str, updated: str) -> dict:
+    """A summary row as get_project_milestone_summary returns it."""
+    return {
+        "id": mid, "user_id": 7, "project_id": 5, "title": f"M{mid}",
+        "description": f"what M{mid} is for", "body": PLAN, "status": status,
+        "order_index": mid, "created_at": "2026-01-01T00:00:00+00:00",
+        "updated_at": updated, "total": 4, "completed": 2, "pct": 50.0,
+        "status_counts": {"todo": 2, "in_progress": 0, "done": 2, "cancelled": 0},
+    }
+
+
+def _history(done: int, active: int) -> list[dict]:
+    """`done` done milestones (higher id = more recently updated), then `active` open ones."""
+    rows = [_row(i, "done", f"2026-08-{i + 1:02d}T00:00:00+00:00") for i in range(done)]
+    rows += [_row(done + i, "active", "2026-01-01T00:00:00+00:00") for i in range(active)]
+    return rows
+
+
+def test_brief_rows_leave_out_the_plan_and_what_the_caller_already_knows():
+    brief, omitted = brief_milestone_summary([_row(1, "active", "2026-09-01")])
+    assert omitted == 0
+    assert brief == [{
+        "id": 1, "title": "M1", "description": "what M1 is for", "status": "active",
+        "order_index": 1, "total": 4, "completed": 2, "pct": 50.0,
+        "status_counts": {"todo": 2, "in_progress": 0, "done": 2, "cancelled": 0},
+    }]
+
+
+def test_cap_keeps_every_open_milestone_and_the_most_recent_done_ones_in_order():
+    rows = _history(done=8, active=3)
+    brief, omitted = brief_milestone_summary(rows, done_kept=2)
+    assert omitted == 6
+    # The two most recently updated done ones (ids 6, 7) and all open ones,
+    # still in order_index order.
+    assert [r["id"] for r in brief] == [6, 7, 8, 9, 10]
+
+
+def test_no_cap_keeps_every_row():
+    brief, omitted = brief_milestone_summary(_history(done=8, active=3))
+    assert omitted == 0
+    assert len(brief) == 11
+
+
+def _enter_stubs(rows: list[dict]):
+    return [
+        patch("scribe.mcp.tools.projects.projects_svc.get_project",
+              AsyncMock(return_value=fake_project(id=5))),
+        patch("scribe.mcp.tools.projects.rulebooks_svc.get_applicable_rules",
+              AsyncMock(return_value={"rules": [], "truncated": False,
+                                      "subscribed_rulebooks": []})),
+        patch("scribe.mcp.tools.projects.milestones_svc.get_project_milestone_summary",
+              AsyncMock(return_value=rows)),
+        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.coverage_svc.cached_coverage",
+              AsyncMock(return_value=None)),
+        patch("scribe.mcp.tools.projects.spawn"),
+    ]
+
+
+@pytest.mark.asyncio
+async def test_enter_project_stays_small_however_long_the_history():
+    """The ceiling is the point: a long-lived project's handshake must not
+    grow with its history. 200 milestones with 5k-character plans would be
+    ~1M characters if bodies rode along."""
+    with contextlib.ExitStack() as stack:
+        for cm in _enter_stubs(_history(done=190, active=10)):
+            stack.enter_context(cm)
+        out = await enter_project(project_id=5)
+
+    summary = out["milestone_summary"]
+    assert all("body" not in m for m in summary)
+    assert sum(m["status"] == "done" for m in summary) == 5
+    assert sum(m["status"] == "active" for m in summary) == 10
+    assert out["milestone_summary_omitted"].startswith("185 older done milestone(s)")
+    assert "list_milestones(5)" in out["milestone_summary_omitted"]
+    assert len(json.dumps(out["milestone_summary"], indent=2)) < 10_000
+
+
+@pytest.mark.asyncio
+async def test_omitted_key_is_absent_when_nothing_was_left_out():
+    """Attached only when it applies (#2483)."""
+    with contextlib.ExitStack() as stack:
+        for cm in _enter_stubs(_history(done=3, active=2)):
+            stack.enter_context(cm)
+        out = await enter_project(project_id=5)
+    assert len(out["milestone_summary"]) == 5
+    assert "milestone_summary_omitted" not in out
+
+
+@pytest.mark.asyncio
+async def test_get_project_uses_the_same_brief_block():
+    with patch("scribe.mcp.tools.projects.projects_svc.get_project",
+               AsyncMock(return_value=fake_project(id=5))), \
+         patch("scribe.mcp.tools.projects.milestones_svc.get_project_milestone_summary",
+               AsyncMock(return_value=_history(done=9, active=1))), \
+         patch("scribe.mcp.tools.projects.rulebooks_svc.get_applicable_rules",
+               AsyncMock(return_value={"rules": [], "truncated": False,
+                                       "subscribed_rulebooks": []})):
+        out = await get_project(project_id=5)
+    assert len(out["milestone_summary"]) == 6
+    assert all("body" not in m for m in out["milestone_summary"])
+    assert out["milestone_summary_omitted"].startswith("4 older done milestone(s)")
+
+
+@pytest.mark.asyncio
+async def test_list_milestones_lists_every_milestone_without_plans():
+    """The call milestone_summary_omitted points to: every milestone, done
+    ones included, and no bodies (get_milestone has the plan)."""
+    with patch("scribe.mcp.tools.milestones.milestones_svc.get_project_milestone_summary",
+               AsyncMock(return_value=_history(done=30, active=2))):
+        out = await list_milestones(project_id=5)
+    assert len(out["milestones"]) == 32
+    assert all("body" not in m for m in out["milestones"])