Two controls that did nothing, and instructions worth reading

**Switching mode mid-reply did nothing.** The mode was snapshotted when the
reply began, so changing to Auto during a long agent reply went on asking about
every call until the next turn. The same snapshot held the chat's allow list,
which means "Always allow this" was accepted, written to the row, and then
ignored for the rest of the reply that had just asked about it -- the same bug,
in the quieter place nobody reported.

`agent/session.py:refresh` re-reads exactly those two, between rounds and never
within one. A round's calls are authorised together, so a switch must not
retroactively approve what is already queued -- which is the property the
reply-long snapshot was protecting by accident, and the reason this is not
simply moved into `_authorise`. It mutates in place, because `as_approved`
copies field references and a replacement would leave the round's approved copy
pointing at the old context.

**The composer's highlighting stayed behind after sending.** htmx fires
afterSwap and afterSettle *before* afterRequest, and the composer empties itself
from `hx-on::after-request` -- so every repaint ran while the box still held the
message. It repaints on afterRequest and on `reset` as well now, deferred a
frame: a form's reset event fires before its fields are actually cleared, so
reading the value in the same turn paints the text that is about to vanish.
Driven under a DOM stub reproducing htmx's real ordering, and confirmed to fail
without the fix.

**plan_update, audited.** It never said to mark a task `doing`, so the plan only
ever showed work already finished, which is the opposite of "what somebody reads
to see where you are". It never said several changes fit in one call, so a model
spends a round per task. And `done` now means checked rather than written.

**New: core.engineering**, an agent-chat fragment about conduct rather than
about any language -- run what you write, find the project's own build and test
commands rather than guessing, read before editing, change one thing at a time,
read the error instead of guessing at a fix, do not broaden an except to make
output clean, and say what you did not check. Every line is about the gap
between having written something and knowing it works, which is the gap a model
closes by asserting.

That pushed the shipped harness to within 1,300 characters of its ceiling, where
crossing it silently severs the project's own AGENTS.md. The ceiling is 20,000
and the test pins a margin as well as a fit -- the headroom is also where an
administrator's own wording goes, and an override is usually longer than the
default it replaces.

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

src/lembas/web/static/js/composer.js

@@ -440,6 +440,22 @@
   document.addEventListener("htmx:afterSwap", paint);
   document.addEventListener("htmx:afterSettle", paint);
 
+  /* And after the *request*, a frame later, which is the one that matters on
+     send. htmx fires afterSwap and afterSettle before afterRequest, and the
+     composer empties itself from `hx-on::after-request` -- so every repaint
+     above ran while the box still held the message, and the highlight stayed
+     behind over an empty field until the next keystroke repainted it.
+
+     A frame later for two reasons: `form.reset()` fires its `reset` event
+     *before* the fields are actually cleared, and reading the value in the same
+     turn would paint the text that is about to disappear. */
+  function repaintSoon() {
+    if (window.requestAnimationFrame) window.requestAnimationFrame(paint);
+    else setTimeout(paint, 0);
+  }
+  document.addEventListener("htmx:afterRequest", repaintSoon);
+  document.addEventListener("reset", repaintSoon);
+
   document.addEventListener("click", function (event) {
     if (!event.target.closest(".composer-menu") &&
         !event.target.closest("[data-composer-input]")) hide();