ui: sidebar tab selector uses text labels instead of icons

The two drawn tab glyphs were judged not understandable enough; the
switcher goes to the wide policy with titles only, and the glyphs,
their gresource entries and the icon-naming code are removed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/claude/invariants-gtk-and-chrome.md

@@ -51,38 +51,20 @@ Part of [CLAUDE.md](../../CLAUDE.md). These are rules that cost a defect to lear
   how the first version of that line earned them. What stays in the menu is what acts on the *data*
   (Fit, Export, Configurations) and the one editor that is not a pane (the layout editor): the signal list
   is a *tab* of the sidebar, so there is nothing left to reveal or hide about it. The Arm/Disarm button in the trigger panel still has text.
-- **Seven of this app's icons are its own, and they are a `GResource` compiled into the
+- **Five of this app's icons are its own, and they are a `GResource` compiled into the
   binary.** No icon theme has a glyph for an oscilloscope trigger, a pair of cursors or a
   measurement ruler, and the stock names those buttons used to carry said something else
   entirely: a *record dot* for the trigger and three different **magnifiers** for cursors,
-  measurements and math. `src/icons/scalable/actions/udpscope-{trigger,cursors,measure,events,resize-rows,tab-measure,tab-signals}-symbolic.svg`
-  are the seven action icons. `udpscope-math-symbolic` left with the toolbar toggle that was its last
+  measurements and math. `src/icons/scalable/actions/udpscope-{trigger,cursors,measure,events,resize-rows}-symbolic.svg`
+  are the five action icons. `udpscope-math-symbolic` left with the toolbar toggle that was its last
   user; `udpscope-measure-symbolic` **stayed**, because the Preferences window's Plot page carries it --
   an icon with a live user is not an orphan, whatever the toggle that introduced it did -- and it is
-  the Preferences window's icon, not the tab's.
+  the Preferences window's icon.
 
-  The two **tabs** got glyphs of their own, and each is a *pair* rather than one of the icons above.
-  `udpscope-tab-measure-symbolic` is two cursors beside the ruler they read against — each a cap over two
-  bold dashes, beside a ruler of two bands with three marks between them and **no end caps** (a closed
-  frame reads as a rectangle, and costs a fifth of the ink on two lines that say nothing) — and
-  `udpscope-tab-signals-symbolic` is a sine crossing its dashed level, beside two bold channel rows. They
-  are not reuses, because a glyph the toolbar already carries means two things the moment a tab shows it
-  too; instead the *trigger's* own icon (`udpscope-trigger-symbolic`) was redrawn to the Signals pill's
-  picture, so the pill and the button that turns the trigger on are recognisably about the same thing.
-  The wave is a **full period and not a hump**: a crest and a trough are what make it read as a wave
-  rather than as a hill, and the level's dashes survive between the crossings. (A hump was tried and
-  reverted — it named the "above the level" half of a trigger and lost the crossings, which is the half
-  that matters.)
-  Both are **32x16** composites drawn **bold** — one thick band, two thick dashes, few features — because
-  at this size a thin wave or a 1px tick reads as *texture* rather than as a shape, which is what "not
-  clear" looks like. Wider than tall on purpose: a 16px square cell carries one motif, not a pair. And
-  **GDK paints an icon into a square box whatever the document's aspect** (measured:
-  `gtk_icon_theme_lookup_icon()` at 32 reports `32x32`, and librsvg fits it to `32x16`), so the pair is
-  letterboxed rather than stretched — and the pill's image is given `pixel_size` 32 in `name_side_tabs()`,
-  which draws the artwork at the size it is written, so its bars stay crisp. Every glyph here is
-  **inset two pixels**, because art flush with the cell edge is what a button's padding or a crop takes a
-  pixel off, and a fractional scale is what would blur it, which is why nothing is drawn at 24 or 48. The
-  two tab glyphs measure 29% and 30% ink, inside the range the icons above them set.
+  The sidebar's **tabs have no icons any more**: two glyphs (`udpscope-tab-measure-symbolic`,
+  `udpscope-tab-signals-symbolic`, each a 32x16 pair) were drawn for them and judged not understandable
+  enough, so the tabs are text and both SVGs were deleted. The *trigger's* own icon was redrawn to the
+  Signals glyph's picture at that time and kept it.
 - **A shortcut table row's `accel` is GTK accelerator syntax, and a pointer gesture has
   none.** `src/shortcuts.cpp`'s strings are handed to `AdwShortcutsItem`, which parses them
   with `gtk_accelerator_parse()` — so they are `"space"`, `"<Control>e"`, `"<Control>slash"`,
@@ -264,16 +246,13 @@ Part of [CLAUDE.md](../../CLAUDE.md). These are rules that cost a defect to lear
   allocation read in the sidebar is a debug capture, and each reads 0 on the page that is *not*
   current -- a change in what the reading means, not a defect, and no functional code may depend on
   those numbers.
-- **`AdwViewSwitcherPolicy.narrow` still draws a label; an *empty title* is what makes a pill an icon.**
-  Measured on libadwaita 1.10: with `narrow` and a title, the pill holds a `GtkImage` **and** a
-  `GtkLabel` — 48px of "Measure" inside a 54px pill — so the policy alone does not give an icon-only tab
-  bar. The sidebar's pages therefore have **no title** (their `name` is what identifies them to
-  `select_side_tab()` and the session file) and the pills are *named in code* instead: the first tick
-  calls `name_side_tabs()`, which walks the switcher's children — the pills are there in page order, and
-  `AdwViewSwitcherButton` is not a public type, so there is no type check to make — and sets each pill's
-  **tooltip and accessible name** from the page's name, then hides the empty label that would otherwise
-  leave the icon off-centre. An icon-only pill is still a named control for a screen reader, and
-  `switcher: … pills=2 labels=0 names=2` is the reading for all three facts at once.
+- **The sidebar's tabs are text: `AdwViewSwitcherPolicy.wide`, a title on every page, no icon.** The
+  built-in pages get their titles in the `.ui` and a source kind's pages from `SourcePanel::title`
+  (`adw_view_stack_add_titled`); the page's *name* still identifies it to `select_side_tab()` and the
+  session file. An icon-only version existed (policy `narrow`, empty titles, the pills named in code by
+  `name_side_tabs()`, because `narrow` still draws a label beside an icon); it was reversed because the
+  glyphs were not understandable. A page added with an empty title is a blank pill, and
+  `switcher: … pills=N labels=N pages=N` reads it as `labels` below `pills`.
 - **An *overlaid* sidebar covers the plot, so a drag out of it has nowhere to land.** `collapsed` in an
   `AdwOverlaySplitView` means the sidebar sits *on* the plot rather than beside it: the pointer is over the
   list, never over a drop target, and a signal can be dragged but not dropped. `row_drag_sidebar()` hides

docs/claude/probe-readings.md

@@ -479,27 +479,14 @@ Two lines of the self-check output are assertions in disguise:
   substitutes a missing-image placeholder, the button still works, and every other line of the
   dump still passes. Changing an icon name is a one-line change in `build_toolbar()` and this
   is the only check that it names something that exists.
-- `switcher: policy=narrow pills=2 labels=0 names=2 icon=32x32 size=308x36` (in the exit dump, beside
-  `panels:`) — the two
-  sidebar tabs as the switcher actually draws them. **`pills=2 labels=0`** is the claim: two pills are on
-  screen and **no text is drawn** (`labels` counts *mapped labels with text*, because `narrow` keeps an
-  empty label in the pill's layout and a plain mapped count would read 2 either way). `names=2` is the
-  other half — both pills carry a tooltip and an accessible name set by `name_side_tabs()`, so an
-  icon-only pill is not an anonymous button — and `pills=0` means nothing is mapped, which makes the
-  rest of the line meaningless rather than a pass. `policy=narrow` is read rather than assumed. `icon=`
-  is the box the pills' `GtkImage` is *rendered* in, which proves the 32px override stuck: the tab
-  glyphs are 32x16 documents, and GDK paints an icon into a square box whatever the document's aspect,
-  so the artwork is drawn 32x16 at 1:1 inside that 32x32 box — letterboxed, not stretched, which is what
-  keeps its 2px bars crisp. It reads `0x0` on the first tick, where nothing has been allocated yet, and
-  is therefore read by the exit probe with the rest of the sidebar's geometry. `size=` is the bar's own
-  size, and it is the answer to "what did the wider glyphs cost": `36` is what it was with 16px icons,
-  because the pill's fixed height takes a 32px box without growing — the glyph gets twice the width for
-  no vertical room at all.
-- `page icons: measure=udpscope-tab-measure-symbolic(ok) signals=udpscope-tab-signals-symbolic(ok)` (in the exit
-  dump, beside `toolbar icons:`) — each tab's own glyph and `gtk_icon_theme_has_icon()`'s verdict, read
-  on the first tick for the same reason the toolbar's are. **Both must read `(ok)`**: the page titles are
-  empty on purpose, so an icon that does not resolve leaves a *blank* pill, and a blank pill looks
-  exactly like a page with nothing in it.
+- `switcher: policy=wide pills=4 labels=4 pages=4 size=308x34` (in the exit dump, beside `panels:`) — the
+  sidebar tabs as the switcher actually draws them, and they are **words**: `labels` counts *mapped labels
+  with text*, so `pills=labels=pages` says every page has a visible title. `pages` is read from the stack
+  (2 for UDPS, 3 for the probe source, 4 for the E-1608 with its Analog out and Digital I/O tabs). A
+  `labels` below `pills` is a page added with an empty title; `pills=0` means nothing is mapped, which
+  makes the rest of the line meaningless rather than a pass. `policy=wide` is read rather than assumed.
+  `size=` is the bar's own size: a text tab costs about 34 px of height, and a width of 308 shows the
+  four tabs fit the 320 px column.
 - `help layer: contextual=on hints=12 ids={events plot status cursors measures trigger trigger_advanced events_record trigger_search signals signals_config window} icon=dialog-information-symbolic(ok) hint=12x12; tour=idle steps=5 step=0 auto=1 requested=0` (in the exit
   dump, beside `switcher:`) — the help affordance layer as the last tick found it. **`hints=` must equal
   the number of ids**, and the ids are the surfaces the contextual help is on: eleven of the window

docs/claude/verification.md

@@ -17,8 +17,8 @@ Two baselines every run is read against. The UDPS runs must be **unchanged by th
 a UDPS self-check, number-normalised (`sed 's/[0-9.]\+/N/g'`), diffs empty against one taken before it.
 A clean build emits **three** warnings and no more: two
 `-Wmissing-field-initializers` on `MathNode::source` and one `-Woverlength-strings` on the icons'
-generated GResource `.c`, whose blob is **12352** against C99's 4095-byte string-literal limit with
-the seven action icons and the two app icons that remain (a note about a generated file, which GCC
+generated GResource `.c`, whose blob is **9248** against C99's 4095-byte string-literal limit with
+the five action icons and the two app icons that remain (a note about a generated file, which GCC
 itself supports). The *fourth* was the help pages' generated `.c` (**516044** bytes); the manual is
 now a Mallard set installed for Yelp rather than a GResource compiled into the binary, so that
 bundle — and its warning — is gone, and the baseline moved from four to **three**. Re-measure by