A ceiling that was a schedule, and a reply that ended in silence

Reported: an ordinary chat with a small local model researching a question
well -- six searches, each one informed by the last -- stopped at the round
limit and produced no answer at all. Two separate faults, and the second is
the serious one.

The limit was 5 and it should not have been a working number. It was 1 once,
and the note beside it already said why that was wrong: a count low enough to
be reached by ordinary work is a schedule, not a ceiling, and it overrides the
model's judgement on every turn instead of catching a runaway. Five was the
same mistake with a larger number. It is 0 now -- no ceiling, falling back to
MAX_TOOL_ROUNDS as a runaway backstop, which is the shape `Limits.steps`
already had for an agent chat. What bounds an ordinary chat is the context
window, which is a real limit rather than a guess at how much looking-up a
question deserves. An administrator who wants a ceiling can still set one.

The worse fault: *every* budget ended the reply where it was noticed. That is
survivable for a model that narrates as it works and produces nothing at all
for one that goes straight to tool calls -- an empty bubble with a red line
under it, and everything it had gathered thrown away. `_wrap_up` withdraws the
tools and asks once more instead. What it found is in the transcript either
way; one request turns it into an answer. Same move `plan_submit` makes, and
the reason the loop now runs to `budget + 2`: the round at the budget notices,
the one after it answers. The event stays, because an answer the model chose to
give and one it gave because it ran out of room read identically otherwise.

`_too_big` is the one exception and stays a hard stop. It *is* the finding that
there is no room for another request, so a wrap-up round would be the same
overflow with an upstream error in place of an explanation.

`core.keep_working` was gated on the agent family and is now gated on
`unbounded`, the exact complement of `round_budget` -- so an ordinary chat with
no ceiling is told to work until the job is done rather than being told nothing,
and is never told it has a budget of two hundred, which it would ration.

The regression test asserts the reply is not empty, and fails with `'' ==
'Here is what I found.'` against the old code -- which is exactly what was seen.

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

src/lembas/services/tools.py

@@ -58,15 +58,21 @@ log = logging.getLogger(__name__)
 # searching is the answer, searching until the context runs out at a full
 # request each.
 #
-# It was briefly 1, which is low enough to stop being a ceiling and start being
-# a schedule: it overrode the model's judgement on every turn rather than
-# catching a runaway. Worse, several built-ins are two-step pairs --
-# `knowledge_get` and `notes_get` read a document "by the id a search returned"
-# -- so one round left the library searchable and not readable.
+# It was 1, then 5, and now 0 meaning no ceiling at all. Both numbers were the
+# same mistake at different scales: low enough to be reached by ordinary work is
+# low enough to be a schedule rather than a ceiling, overriding the model's
+# judgement on every turn instead of catching a runaway. One left the library
+# searchable and not readable, since `knowledge_get` and `notes_get` read a
+# document "by the id a search returned". Five ended a piece of research at its
+# sixth search.
+#
+# What bounds an ordinary chat now is the context window, and the loop falls
+# back to `generation.MAX_TOOL_ROUNDS` as a runaway backstop -- the shape
+# `Limits.steps` already had for an agent chat.
 #
 # `settings_store.chat_rounds()` is what the loop and the harness read; this is
 # the fallback for callers with no session, and a test pins the two together.
-MAX_ROUNDS = 5
+MAX_ROUNDS = 0
 
 # Tool families, matching the per-model capability flags and the permission
 # keys. The three names differ by prefix only, which is deliberate: adding a