Two panes, two modes. **Locked** is what a returning user gets: the trigger pane shows one line saying
what it is set to, the signal list shows only the signals that are on, and neither offers a control that
changes the configuration — each heading has an `[edit]` button (the Adwaita `emblem-system-symbolic`,
swapping to `emblem-ok-symbolic` in configuration mode) that flips its pane. A **first run** — no session
file for that source — never reaches `apply_layout()` and comes up in configuration mode, because
configuring the host is what a first run is for. The mode is a mode and not a setting, so it is
deliberately not persisted.
The locked signal list drops the rows of every signal that is off, which is the whole of "show active
signals": the list already filters on nothing, so the lock is one `continue`. With the rows go the acquire
tick, the overflow menu (Information, Calibrate…, Delete, rename) and the `MATH` divider's `+` — and the
colour chip stops being clickable, because choosing a colour is configuration too. Dragging a signal onto
a plot stays: that is which view shows what, not what the scope is set up to do.
**The trigger is persisted, settings and state both** — the settings *even while it is off*, which is the
point: a trigger configured once and switched off is still the trigger you come back to. `LayoutState`
gains fifteen flat `trigger_*` keys; the channel is stored by *name* (every rebuild renumbers the
channels, the model's own rule) and the two enumerations as **the words the panel's dropdowns show**,
because an index ties the file to a declaration order — the lesson `math_op_at()` already carries. The
words are shared with the panel now (`trigger_type_text()` and friends build the dropdown arrays), so the
two cannot drift.
Two ordering traps, both found by running it:
- **The channel name resolves twice over.** `rebuild_trigger_signals()` picks up
`App::pending_trigger_channel` when the stream arrives *after* the load, and `apply_trigger_layout()`
resolves it itself when the channels are already there — without the second path the name stayed
pending past the one rebuild that would have used it, and the trigger silently sat on channel 0
(`summary='pulse width · sine …'` where the session said `square`).
- **The trigger's state is applied by pressing the control, not by setting a flag**: the toggle is set
*outside* the `updating_panels` window `apply_layout()` uses, because a toggle set inside it emits
`toggled` into a handler that returns at once and nothing would happen — no arming, no events button,
no sensitivity.
Verified, in both modes and both directions:
panes: trigger=locked signals=locked body_visible=0 summary='window · square · 0.3…0.6 · 20 % pre'
panes: trigger=config signals=config body_visible=1 summary=''
signals panel: labels=2 list=1 rows=7 signals=2 math=4 divider=1
The locked trigger pane is 42 px tall against 580 unlocked. A hand-written session round-trips: every
value it named came back in the panel's own controls, `trigger=1/1` (the state arrived and the pane's
switch followed it), and the file the app wrote back carried all fifteen keys with the untouched ones at
their defaults. `[side-tab-probe] … advanced=4` on its documented recipe; `make test-ui` 14 files; zero
`Gtk-CRITICAL` and no missing icon.
Docs: the `panes:` reading with what each field means, the corrected `labels=` note (the panel's frame is
counted above the list now, because the heading sits in a heading row), the invariants for both the
persistence and the lock, the README's deviation note, and the removal of its claim that the trigger has
never been persisted — it is now, and the locked view is built from exactly that.
GTK4 and libadwaita. It receives one UDP stream through the vendored
udpsclient, buffers it in a large ring, and draws it with the vendored
plotter: a trigger with a pre/post event window, a pause that freezes the
window, cursors, measurements, math channels in a node editor, an event cache,
named configurations, preferences, and an export of the visible window to
.npy/.csv. Waveform files can be opened and analysed in place.
The interface is two threads -- a producer that owns the socket and the GTK
main thread that owns every widget and the GL context -- sharing one model
under one mutex, with samples crossing through lock-free rings.
deps/plotter is a submodule pinned to the commit this tree builds against;
deps/udpsclient is vendored in place. docs/claude/ documents the rules that
cost a defect to learn, and SPECS.md is the requirement document.
Martino Ferrari