Two places where the editor bar spent width on nothing.
The file explorer put its label and its buttons on one line: WORKSPACE next
to new/open/save, and every board section's name next to rename / new file /
new folder plus the status dot. Between them those set a floor under the
panel's width, and the board name — the one thing a user reads there — got
whatever was left ("M5 Cardput..." in a 150px pane). Both headers now stack:
the label owns its row, the actions sit above (board) or below (workspace),
and the status dot rides in the actions row, where it costs the name
nothing. The actions row keeps its height reserved whether or not the
buttons are showing, so hovering a section never shoves the files below it
down. Default pane width 150 -> 124px; the freed px go to the code editor.
The toolbar's center slot is a flexible spacer that pins the right icons to
the far right, and nothing renders into it (no caller passes centerSlot). So
whenever the bar had width to spare — closing the docked AI chat is exactly
that — the spacer ate it: 191px of black between Reset and Libraries on a
1600px window. Empty, it no longer grows, so the editor controls stay packed
and the surplus collects at the one boundary that already carries a divider,
in front of the canvas controls (which belong over the canvas pane).