core/agent+tools+cli: number todos by listing order, not the internal id

src/plyngent/agent/todo_stack.py

@@ -14,7 +14,7 @@ _REVIEW_OPEN_TITLE_LIMIT = 8
 class TodoItem(Struct, omit_defaults=True):
     """One task inside a group (siblings share a group; not stacked individually)."""
 
-    id: str
+    id: str  # stored key only — a listing numbers items by render order, never by id
     title: str
     status: TodoStatus = "pending"
     notes: str = ""
@@ -39,7 +39,8 @@ class TodoStack:
     - **Push** always creates **one new group** containing one or more sibling
       tasks (``push T1, T2`` is one frame, not two stack levels).
     - **Pop** removes the entire **top group**.
-    - Within a group, update tasks by id (done / in_progress / …).
+    - **Update** takes the 1-based number a listing shows (TOP group first); the
+      stored ``id`` never leaves the stack.
 
     Breakdown pattern::
 
@@ -161,13 +162,26 @@ class TodoStack:
         raw = cast("dict[object, object]", out)
         return {str(key): value for key, value in raw.items()}
 
+    def _render_order(self) -> list[tuple[TodoGroup, int, TodoItem]]:
+        """``(group, index, item)`` in listing order — TOP group first.
+
+        A listing numbers these 1-based, so an item's position here *is* the
+        number it is shown (and updated) by.
+        """
+        ordered: list[tuple[TodoGroup, int, TodoItem]] = []
+        for group in reversed(self._data.groups):
+            ordered.extend((group, index, item) for index, item in enumerate(group.items))
+        return ordered
+
     def render(self) -> str:
         if not self._data.groups:
             return "(todo stack empty — no groups)"
         lines: list[str] = [
             f"(LIFO of groups: depth={self.depth}; TOP group = current breakdown level)",
         ]
-        # Top group first for the model.
+        # Top group first for the model; the running number is the item's
+        # position in :meth:`_render_order`, the same list ``update`` resolves.
+        number = 0
         for offset, group in enumerate(reversed(self._data.groups)):
             depth = self.depth - 1 - offset
             tag = " TOP" if offset == 0 else ""
@@ -176,6 +190,7 @@ class TodoStack:
                 lines.append("  (empty group)")
                 continue
             for item in group.items:
+                number += 1
                 mark = {
                     "pending": "[ ]",
                     "in_progress": "[~]",
@@ -183,7 +198,7 @@ class TodoStack:
                     "cancelled": "[-]",
                 }.get(item.status, "[?]")
                 note = f" — {item.notes}" if item.notes else ""
-                lines.append(f"  {mark} {item.id}: {item.title}{note}")
+                lines.append(f"  {mark} {number}. {item.title}{note}")
         return "\n".join(lines)
 
     def turn_reminder_prompt(self) -> str:
@@ -220,7 +235,7 @@ class TodoStack:
             headline,
             action,
             "Tools: todo_list | todo_push(titles=[...]) | todo_update | todo_pop | todo_clear",
-            "Rules: TOP = current level; push = one sibling group; pop = whole TOP group.",
+            "Rules: TOP = current level; push = one sibling group; pop = whole TOP group; update by listing number.",
             "Stack:",
             self.render(),
         ]
@@ -232,7 +247,7 @@ class TodoStack:
         n_open = len(open_items)
         n_groups = self.depth
         if n_open:
-            open_titles = "; ".join(f"{item.id}:{item.title}" for item in open_items[:_REVIEW_OPEN_TITLE_LIMIT])
+            open_titles = "; ".join(item.title for item in open_items[:_REVIEW_OPEN_TITLE_LIMIT])
             if n_open > _REVIEW_OPEN_TITLE_LIMIT:
                 open_titles += f"; …(+{n_open - _REVIEW_OPEN_TITLE_LIMIT} more)"
             headline = (
@@ -258,7 +273,7 @@ class TodoStack:
             headline,
             action,
             "Tools: todo_list | todo_push(titles=[...]) | todo_update | todo_pop | todo_clear",
-            "Rules: TOP group = current level; push=one sibling group; pop=remove whole TOP group.",
+            "Rules: TOP = current level; push = one sibling group; pop = whole TOP group; update by listing number.",
             "Stack:",
             self.render(),
         ]
@@ -326,36 +341,34 @@ class TodoStack:
             self.mark_touched()
         return n
 
-    def get(self, item_id: str) -> TodoItem | None:
-        for item in self.all_items():
-            if item.id == item_id:
-                return item
-        return None
-
     def update(
         self,
-        item_id: str,
+        number: int,
         *,
         title: str | None = None,
         status: TodoStatus | None = None,
         notes: str | None = None,
     ) -> TodoItem:
-        for group in self._data.groups:
-            for index, item in enumerate(group.items):
-                if item.id != item_id:
-                    continue
-                new_title = title.strip() if title is not None else item.title
-                if not new_title:
-                    msg = "title must not be empty"
-                    raise ValueError(msg)
-                new_status = status if status is not None else item.status
-                new_notes = notes if notes is not None else item.notes
-                updated = TodoItem(id=item.id, title=new_title, status=new_status, notes=new_notes)
-                group.items[index] = updated
-                self.mark_touched()
-                return updated
-        msg = f"unknown todo id {item_id!r}"
-        raise KeyError(msg)
+        """Update the item a listing shows as *number* (1-based, TOP group first).
+
+        Numbers are listing positions, not stored ids: a push/pop shifts them, so
+        they have to come from the latest listing.
+        """
+        ordered = self._render_order()
+        if not 1 <= number <= len(ordered):
+            msg = f"no todo item {number}: the list has {len(ordered)} item(s); pick a number from the latest listing"
+            raise ValueError(msg)
+        group, index, item = ordered[number - 1]
+        new_title = title.strip() if title is not None else item.title
+        if not new_title:
+            msg = "title must not be empty"
+            raise ValueError(msg)
+        new_status = status if status is not None else item.status
+        new_notes = notes if notes is not None else item.notes
+        updated = TodoItem(id=item.id, title=new_title, status=new_status, notes=new_notes)
+        group.items[index] = updated
+        self.mark_touched()
+        return updated
 
 
 def parse_push_titles(raw: str) -> list[str]:

src/plyngent/cli/slash.py

@@ -420,12 +420,12 @@ def complete_slash_args(
             if flags:
                 return sorted(set(flags))
 
-        # Contextual /todos second token: todo ids after done|cancel|pending|in_progress.
+        # Contextual /todos second token: listing numbers after done|cancel|…
         if name == "todos" and prior:
             action = prior[0].lower()
             if action in {"done", "cancel", "pending", "in_progress"} and len(prior) == 1:
-                ids = [item.id for item in state.todo_stack.all_items()]
-                return [i for i in ids if i.startswith(incomplete)]
+                numbers = [str(n) for n in range(1, len(state.todo_stack.all_items()) + 1)]
+                return [n for n in numbers if n.startswith(incomplete)]
 
         # Positional arguments: complete the next unset argument.
         arg_params = [p for p in cmd.params if isinstance(p, click.Argument)]
@@ -1524,10 +1524,10 @@ def todos_cmd(  # noqa: C901, PLR0911, PLR0915 — one branch per /todos action
 ) -> None:
     """Show or edit the LIFO stack of **task groups**.
 
-    ``/todos`` — list (top group first)
+    ``/todos`` — list (top group first; items numbered as shown)
     ``/todos push T1; T2`` — one new group of siblings
     ``/todos pop`` — pop entire top group
-    ``/todos done <id>`` / ``/todos cancel <id>`` — set status
+    ``/todos done <number>`` / ``/todos cancel <number>`` — set status
     ``/todos clear`` — wipe stack
     """
     from plyngent.agent.todo_stack import parse_push_titles
@@ -1552,8 +1552,8 @@ def todos_cmd(  # noqa: C901, PLR0911, PLR0915 — one branch per /todos action
             click.echo(f"error: {exc}")
             return
         _await(state.persist_todo_stack())
-        ids = ", ".join(i.id for i in group.items)
-        click.echo(f"pushed group depth={stack.depth} items=[{ids}]")
+        pushed = ", ".join(i.title for i in group.items)
+        click.echo(f"pushed group depth={stack.depth} items=[{pushed}]")
         click.echo(stack.render())
         return
     if act == "pop":
@@ -1562,13 +1562,13 @@ def todos_cmd(  # noqa: C901, PLR0911, PLR0915 — one branch per /todos action
             click.echo("todo stack empty")
             return
         _await(state.persist_todo_stack())
-        titles = ", ".join(f"{i.id}:{i.title}" for i in group.items) or "(empty)"
-        click.echo(f"popped TOP group ({titles})")
+        popped = ", ".join(i.title for i in group.items) or "(empty)"
+        click.echo(f"popped TOP group ({popped})")
         click.echo(stack.render())
         return
     if act in {"done", "cancel", "pending", "in_progress"}:
         if not rest:
-            click.echo(f"error: usage: /todos {act} <id>")
+            click.echo(f"error: usage: /todos {act} <number>")
             return
         if act == "done":
             new_status = "done"
@@ -1579,12 +1579,17 @@ def todos_cmd(  # noqa: C901, PLR0911, PLR0915 — one branch per /todos action
         else:
             new_status = "in_progress"
         try:
-            item = stack.update(rest[0], status=new_status)
-        except (KeyError, ValueError) as exc:
+            number = int(rest[0].strip())
+        except ValueError:
+            click.echo(f"error: /todos {act} takes an item number from the list (e.g. /todos {act} 2)")
+            return
+        try:
+            item = stack.update(number, status=new_status)
+        except ValueError as exc:
             click.echo(f"error: {exc}")
             return
         _await(state.persist_todo_stack())
-        click.echo(f"updated {item.id} → {item.status}")
+        click.echo(f"updated {number} → {item.status}")
         click.echo(stack.render())
         return
     if act == "clear":

src/plyngent/config/models.py

@@ -97,6 +97,9 @@ otherwise a small default is used. Never rely on shell to spoof identity.
 ### Todos
 - Use the todo stack for multi-step work (LIFO groups: push related items, finish/update, \
 pop the group). Open items mean unfinished work.
+- A listing numbers items in the order it shows them (TOP group first); those numbers are \
+positions, not ids, and shift when the stack changes — `todo_update` takes the number from \
+the latest listing.
 - The stack does **not** auto-clear. When every task is done (all items done/cancelled), \
 call `todo_clear` (or pop finished TOP groups) so no hygiene noise is left behind.
 """

src/plyngent/tools/todo.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 from typing import TYPE_CHECKING, cast
 
 from plyngent.agent import ToolTag, tool
+from plyngent.tools.chat.shape import number_arg
 
 if TYPE_CHECKING:
     from collections.abc import Callable
@@ -52,6 +53,10 @@ async def _with_todo_stack(mutator: Callable[[TodoStack], str]) -> str:
 async def todo_list() -> str:
     """Show the LIFO stack of **task groups** (TOP group = current breakdown level).
 
+    Items are numbered in the order they print (1-based, TOP group first). Those
+    numbers are listing positions, not stored ids, so they shift whenever the
+    stack changes — take them from the latest listing.
+
     Non-empty stack with open (pending/in_progress) items = unfinished work.
     All-terminal but non-empty = hygiene only (pop/clear). Push creates one
     group of siblings; pop removes the whole top group.
@@ -82,8 +87,8 @@ async def todo_push(titles: list[str], notes: str = "") -> str:
             group = stack.push_group(parsed, notes=notes)
         except ValueError as exc:
             return f"error: {exc}"
-        ids = ", ".join(i.id for i in group.items)
-        return f"pushed group (depth={stack.depth}) items=[{ids}]\n{stack.render()}"
+        pushed = ", ".join(i.title for i in group.items)
+        return f"pushed group (depth={stack.depth}) items=[{pushed}]\n{stack.render()}"
 
     return await _with_todo_stack(_run)
 
@@ -100,27 +105,36 @@ async def todo_pop() -> str:
         group = stack.pop()
         if group is None:
             return "todo stack empty"
-        titles = ", ".join(f"{i.id}:{i.title}" for i in group.items) or "(empty)"
+        popped_titles = ", ".join(i.title for i in group.items) or "(empty)"
         top = stack.top_group
-        top_s = "(empty)" if top is None else ", ".join(i.id for i in top.items)
-        return f"popped TOP group ({titles}); new top group=[{top_s}]\n{stack.render()}"
+        top_titles = "(empty)" if top is None else ", ".join(i.title for i in top.items)
+        return f"popped TOP group ({popped_titles}); new top group=[{top_titles}]\n{stack.render()}"
 
     return await _with_todo_stack(_run)
 
 
 @tool(name="todo_update", tags=ToolTag.LOCAL | ToolTag.PUBLIC | ToolTag.SESSION_STATE)
 async def todo_update(
-    item_id: str,
+    number: int,
     status: str = "",
     title: str = "",
     notes: str = "",
 ) -> str:
-    """Update a task by id inside any group.
+    """Update a task by the number the listing shows (1-based, TOP group first).
 
-    Open items are unfinished work: mark done/cancelled when the work is truly
-    finished (not just deferred). Pop the TOP group when that breakdown level
-    is complete so the stack does not linger as false open work.
+    Numbers come from the latest listing and shift when the stack changes, so
+    re-list rather than reusing an older number. Open items are unfinished work:
+    mark done/cancelled when the work is truly finished (not just deferred). Pop
+    the TOP group when that breakdown level is complete so the stack does not
+    linger as false open work.
     """
+    item_number, number_error = number_arg("todo_update", "number", number, example="2")
+    if number_error is not None:
+        return f"error: {number_error}"
+    assert item_number is not None  # number_arg returns a value whenever it accepts
+    if not item_number.is_integer():
+        return "error: `todo_update` expects `number` as a whole item number; pass e.g. 2"
+    target = int(item_number)
 
     def _run(stack: TodoStack) -> str:
         status_arg: TodoStatus | None = None
@@ -131,14 +145,14 @@ async def todo_update(
             status_arg = cast("TodoStatus", token)
         try:
             item = stack.update(
-                item_id.strip(),
+                target,
                 title=title if title.strip() else None,
                 status=status_arg,
                 notes=notes if notes != "" else None,
             )
-        except (KeyError, ValueError) as exc:
+        except ValueError as exc:
             return f"error: {exc}"
-        return f"updated {item.id} → {item.status}: {item.title}\n{stack.render()}"
+        return f"updated {target} → {item.status}: {item.title}\n{stack.render()}"
 
     return await _with_todo_stack(_run)
 

tests/test_agent/test_todo_stack.py

@@ -66,6 +66,29 @@ def test_ids_reuse_after_pop() -> None:
     assert g3.items[0].id == "t3"
 
 
+def test_render_numbers_follow_listing_order() -> None:
+    """Numbers are listing positions (TOP group first), never the stored ids."""
+    stack = TodoStack()
+    root = stack.push_group(["root", "sibling"])  # stored ids t1, t2
+    _ = stack.push_group(["child"])  # stored id t3
+    listing = stack.render()
+    assert "  [ ] 1. child" in listing
+    assert "  [ ] 2. root" in listing
+    assert "  [ ] 3. sibling" in listing
+    assert "t1" not in listing
+    assert "t3" not in listing
+
+    # update(1) is the first item the listing shows — the one stored as t3.
+    updated = stack.update(1, status="done")
+    assert updated.id == "t3"
+    assert updated.title == "child"
+    assert updated.status == "done"
+    assert root.items[0].status == "pending"
+
+    with pytest.raises(ValueError, match="no todo item 4"):
+        stack.update(4, status="done")
+
+
 def test_push_is_group_not_per_task_stack() -> None:
     """Multi-title push is one group; pop removes the whole group."""
     stack = TodoStack()
@@ -94,11 +117,16 @@ def test_dfs_breakdown_with_groups() -> None:
     root = stack.push_group(["T1", "T2"])
     children = stack.push_group(["T1.1", "T1.2"])
     assert stack.depth == 2
-    stack.update(children.items[0].id, status="done")
-    stack.update(children.items[1].id, status="done")
+    # Numbers come from the listing: the pushed children are the TOP group → 1, 2.
+    stack.update(1, status="done")
+    stack.update(2, status="done")
+    assert [i.status for i in children.items] == ["done", "done"]
     _ = stack.pop()
     assert stack.depth == 1
-    stack.update(root.items[0].id, status="done")
+    # Children gone: the root group is the listing again → 1 is T1, 2 is T2.
+    stack.update(1, status="done")
+    assert root.items[0].status == "done"
+    assert root.items[1].status == "pending"
     _ = stack.push_group(["T2.1"])
     assert stack.depth == 2
     assert stack.top_group is not None
@@ -119,14 +147,14 @@ def test_single_title_still_one_group() -> None:
 def test_todo_stack_needs_review() -> None:
     stack = TodoStack()
     assert not stack.needs_review()
-    item = stack.push("work")
+    _ = stack.push("work")
     stack.begin_turn()
     # Non-empty + untouched → nag (open or hygiene).
     assert stack.needs_review()
     # Any todo_* access this turn suppresses end-of-turn nag, even with open items.
     stack.mark_touched()
     assert not stack.needs_review()
-    stack.update(item.id, status="done")
+    stack.update(1, status="done")
     stack.begin_turn()
     # Terminal-only stack: same gate (untouched only).
     assert stack.needs_review()
@@ -212,7 +240,7 @@ def test_inject_todo_nag_strategies() -> None:
 
 def test_todo_prompts_signal_undone_work() -> None:
     stack = TodoStack()
-    item = stack.push("open work")
+    _ = stack.push("open work")
     reminder = stack.turn_reminder_prompt()
     assert "[TODO OPEN WORK]" in reminder
     assert "Stack not empty" in reminder
@@ -223,9 +251,9 @@ def test_todo_prompts_signal_undone_work() -> None:
     assert "[TODO OPEN WORK]" in review
     assert "undone work" in review.lower() or "open item" in review.lower()
     assert "open work" in review
-    assert "t1:open work" in review or "open work" in review
+    assert "1. open work" in review  # the review embeds the numbered listing
 
-    stack.update(item.id, status="done")
+    stack.update(1, status="done")
     terminal_review = stack.review_prompt()
     assert "[TODO HYGIENE]" in terminal_review
     assert "done/cancelled" in terminal_review

tests/test_cli/test_display.py

@@ -174,28 +174,28 @@ async def test_pretty_todo_push(capsys: pytest.CaptureFixture[str]) -> None:
         )
     )
     result = (
-        "pushed group (depth=1) items=[a1]\n"
+        "pushed group (depth=1) items=[T1]\n"
         "(LIFO of groups: depth=1; TOP group = current breakdown level)\n"
         "group d=0 TOP:\n"
-        "  [ ] a1: T1"
+        "  [ ] 1. T1"
     )
     await render_events(_aiter([call, _result(result)]))
     out = capsys.readouterr().out
     assert "* Todo Push:" in out
-    assert "  [ ] a1: T1" in out
+    assert "  [ ] 1. T1" in out
     assert "[tool]" not in out
 
 
 async def test_pretty_todo_batch_merges_to_one_stack(capsys: pytest.CaptureFixture[str]) -> None:
     """A batch of todo calls: one summary line, then the last result's stack."""
-    stack = "(LIFO of groups: depth=1; TOP group = current breakdown level)\ngroup d=0 TOP:\n  [ ] a1: T1"
+    stack = "(LIFO of groups: depth=1; TOP group = current breakdown level)\ngroup d=0 TOP:\n  [ ] 1. T1"
     await render_events(
         _aiter(
             [
                 _pretty_call("todo_push", '{"titles": ["T1"]}'),
-                _pretty_call("todo_update", '{"item_id": "a1", "status": "done"}'),
-                _result(f"pushed group (depth=1) items=[a1]\n{stack}"),
-                _result(f"updated a1 → done: T1\n{stack}"),
+                _pretty_call("todo_update", '{"number": 1, "status": "done"}'),
+                _result(f"pushed group (depth=1) items=[T1]\n{stack}"),
+                _result(f"updated 1 → done: T1\n{stack}"),
             ]
         )
     )
@@ -206,14 +206,14 @@ async def test_pretty_todo_batch_merges_to_one_stack(capsys: pytest.CaptureFixtu
     # Only the last result is printed, so the stack renders once.
     assert out.count("group d=0 TOP:") == 1
     assert "pushed group" not in out
-    assert "updated a1 → done: T1" in out
+    assert "updated 1 → done: T1" in out
 
 
 async def test_pretty_todo_batch_mixed_with_other_tool_stays_per_call(
     capsys: pytest.CaptureFixture[str],
 ) -> None:
     """A batch holding a non-todo call keeps one line (and stack) per todo call."""
-    stack = "group d=0 TOP:\n  [ ] a1: T1"
+    stack = "group d=0 TOP:\n  [ ] 1. T1"
     await render_events(
         _aiter(
             [
@@ -867,13 +867,13 @@ async def test_pretty_vcs_kind_branch_and_diff(capsys: pytest.CaptureFixture[str
 
 
 async def test_pretty_todo_list_pop_and_clear(capsys: pytest.CaptureFixture[str]) -> None:
-    stack = "  [ ] a1: T1\n  [x] a2: T2"
+    stack = "  [ ] 1. T1\n  [x] 2. T2"
     await render_events(_aiter([_pretty_call("todo_list", "{}"), _result(stack)]))
     out = capsys.readouterr().out
     assert "* Todo List:" in out
-    assert "  [ ] a1: T1" in out
+    assert "  [ ] 1. T1" in out
 
-    await render_events(_aiter([_pretty_call("todo_pop", "{}"), _result(f"popped TOP group (a1:T1)\n{stack}")]))
+    await render_events(_aiter([_pretty_call("todo_pop", "{}"), _result(f"popped TOP group (T1)\n{stack}")]))
     out = capsys.readouterr().out
     assert "* Todo Pop:" in out
 

tests/test_cli/test_readline_setup.py

@@ -194,9 +194,9 @@ def test_complete_slash_args_from_registry(tmp_path: object) -> None:
 
     state.todo_stack = TodoStack()
     _ = state.todo_stack.push_group(["alpha", "beta"])
-    ids = complete_slash_args(state, "/todos", "t", prior_args=["done"])
-    assert "t1" in ids
-    assert "t2" in ids
+    numbers = complete_slash_args(state, "/todos", "", prior_args=["done"])
+    assert numbers == ["1", "2"]
+    assert complete_slash_args(state, "/todos", "2", prior_args=["done"]) == ["2"]
 
     state.remember_session_ids([3, 12, 40])
     assert complete_slash_args(state, "/resume", "1") == ["12"]

tests/test_cli/test_repl_commands.py

@@ -757,3 +757,26 @@ async def test_btw_read_notice_states_read_only_scope(
     assert "read-only" in notice.body
     assert "not saved" in notice.body
     assert "[notice] aside: read tools" in capsys.readouterr().out
+
+
+async def test_todos_update_takes_a_listing_number(state: ReplState, capsys: pytest.CaptureFixture[str]) -> None:
+    assert await handle_slash(state, "/todos push first; second") is True
+    out = capsys.readouterr().out
+    assert "pushed group depth=1 items=[first, second]" in out
+    assert "  [ ] 1. first" in out
+    assert "  [ ] 2. second" in out
+    assert "t1" not in out
+
+    assert await handle_slash(state, "/todos done 2") is True
+    out = capsys.readouterr().out
+    assert "updated 2 → done" in out
+    assert "  [x] 2. second" in out
+
+    # The stored id is not an address: only listing numbers are.
+    assert await handle_slash(state, "/todos done t1") is True
+    assert "takes an item number from the list" in capsys.readouterr().out
+    assert await handle_slash(state, "/todos done 7") is True
+    assert "no todo item 7" in capsys.readouterr().out
+
+    assert await handle_slash(state, "/todos pop") is True
+    assert "popped TOP group (first, second)" in capsys.readouterr().out

tests/test_tools/test_todo_session.py

@@ -101,6 +101,33 @@ async def test_session_on_todo_change_fires() -> None:
     assert hits == ["session"]
 
 
+async def test_todo_update_uses_listing_numbers() -> None:
+    store = MemoryViewStore({})
+    session = SessionState(session_id="numbers", data=session_data_view(store=store))
+    registry = ToolRegistry(list(TODO_TOOLS), session_state=session)
+
+    out = await registry.execute("todo_push", '{"titles": ["root"]}')
+    assert "pushed group (depth=1) items=[root]" in out
+    out = await registry.execute("todo_push", '{"titles": ["child"]}')
+    assert "pushed group (depth=2) items=[child]" in out
+    # TOP group first; the stored ids stay out of every result.
+    assert "  [ ] 1. child" in out
+    assert "  [ ] 2. root" in out
+    assert "t1" not in out and "t2" not in out
+
+    numbered = await registry.execute("todo_update", '{"number": 2, "status": "done"}')
+    assert "updated 2 → done: root" in numbered
+    assert "  [x] 2. root" in numbered
+
+    stale = await registry.execute("todo_update", '{"number": 9, "status": "done"}')
+    assert stale.startswith("error: no todo item 9")
+    shaped = await registry.execute("todo_update", '{"number": "first"}')
+    assert shaped.startswith("error: `todo_update` expects `number`")
+
+    popped = await registry.execute("todo_pop", "{}")
+    assert "popped TOP group (child); new top group=[root]" in popped
+
+
 async def test_todo_without_session_errors() -> None:
     registry = ToolRegistry(list(TODO_TOOLS))
     out = await registry.execute("todo_list", "{}")