feat(409): the reporting reflex reaches every surface a session reads (#4012)

Step 3 of milestone 409 "Response shapes". Step 2's reporting-back skill
only helps if it fires, and only exists in the Claude Code plugin.

- scribe_static_context.md and using-scribe (new reflex 11) say: report back
  in a shape the operator can read, placed from the `placement` block rather
  than memory, and point at the reporting-back skill. using-scribe also lists
  it among the sibling process-skills.
- update_task returns a one-line `report_back` cue when a task is closed
  (done or cancelled). A tool response is the only surface every MCP client
  sees, at the moment the report is about to be written.
- _INSTRUCTIONS takes no line: there is no budget without trading out a
  session-start reflex. The decision is recorded in server.py's comment
  block so it is not re-litigated blind.
- Guards: test_instruction_surfaces_agree pins the reflex and the placement
  pointer on both plugin surfaces; a tool test pins the cue on closing
  statuses and its absence on every other update.

Plugin version minted.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/scribe/mcp/server.py

@@ -34,6 +34,13 @@ from quart import Quart
 # competing for the last ~68 characters, so an addition here is a trade, never
 # an append.
 #
+# Milestone 409 step 3 (reporting back to the operator in a readable shape)
+# took NO line here, deliberately: there is no room without trading out a
+# session-start reflex, and the moment it applies is when a task closes. So it
+# rides in-band instead — update_task returns `placement` and a one-line
+# `report_back` cue on done/cancelled, which every MCP client sees — with the
+# full shapes in the reporting-back skill and the static context.
+#
 # Milestone 317 (a note's own verify_with / expires_when, and the sweep over
 # them) was DECLINED a line, deliberately, by the operator — not overlooked.
 # The reasoning, so it is not re-litigated blind: this is a map, and its own

src/scribe/mcp/tools/tasks.py

@@ -271,6 +271,9 @@ async def update_task(
     work sits and what comes next — read them from here rather than
     reconstructing them, because a remembered milestone title or "next step"
     reads exactly like a real one when it is wrong.
+
+    Closing a task (done or cancelled) also returns `report_back`: a one-line
+    reminder of what the reply to the operator should cover.
     """
     uid = current_user_id()
     fields: dict = {}
@@ -308,7 +311,10 @@ async def update_task(
     await systems_tools.attach_systems(
         uid, getattr(note, "user_id", uid) or uid, data, task_id, note.project_id
     )
-    return await placement_svc.attach_placement(uid, data, note)
+    await placement_svc.attach_placement(uid, data, note)
+    if status in _CLOSING_STATUSES:
+        data["report_back"] = REPORT_BACK_CUE
+    return data
 
 
 async def add_task_log(task_id: int, content: str) -> dict:
@@ -344,6 +350,17 @@ async def add_task_log(task_id: int, content: str) -> dict:
     return data
 
 
+# The in-band half of milestone 409 step 3. The reporting-back skill and the
+# static context carry the full shapes, but both live only in the Claude Code
+# plugin; a tool response reaches every MCP client, at the moment a piece of
+# work closes, which is exactly when the report is about to be written. One
+# line on purpose: a template here would be read as the reply itself.
+_CLOSING_STATUSES = ("done", "cancelled")
+REPORT_BACK_CUE = (
+    "Reporting this to the operator? Say where it sits (from `placement`), "
+    "what now works, what needs them, and what comes next."
+)
+
 _ITEM_KEYS = {"title", "body", "type", "status", "priority", "kind", "tags", "system_ids"}