help: the search block's (i) on its header, a 12 px mark, and a real search page

docs/claude/probe-readings.md

@@ -395,15 +395,17 @@ Two lines of the self-check output are assertions in disguise:
   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.
-- `help layer: contextual=on hints=11 ids={events plot status cursors measures trigger trigger_advanced events_record signals signals_config window} icon=dialog-information-symbolic(ok) hint=16x16; tour=idle steps=5 step=0 auto=1 requested=0` (in the exit
+- `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: ten of the window
+  the number of ids**, and the ids are the surfaces the contextual help is on: eleven of the window
   itself, and `math` only while the math editor is open (its heading lives in a builder that is rebuilt
-  on every opening, so it is not one of the window's own). Three of the ten are not a pane's *heading*
+  on every opening, so it is not one of the window's own). Four of the eleven are not a pane's *heading*
   but the row of a specific control — `events_record` (the "record events" switch in the trigger
-  panel), `trigger_advanced` (the pre-trigger share row) and `signals_config` (the signals pane's hint
-  line, whose box exists so a hint can join it) — which is the rule the layer follows: a hint is a
-  sibling of the thing it explains and never an overlay on it. The layer is **off by default**
+  panel), `trigger_advanced` (the pre-trigger share row), `trigger_search` (the *header* of the search
+  block's expander, which is what lets it be on screen while the block is collapsed) and
+  `signals_config` (the signals pane's hint line, whose box exists so a hint can join it) — which is
+  the rule the layer follows: a hint is a sibling of the thing it explains and never an overlay on
+  it. The layer is **off by default**
   (`contextual_help` in `settings.toml` is false for a missing file), so a fresh-config run reads
   `contextual=off hints=0` and that line above is the state *after* the Help row was switched on;
   `contextual=off` beside a non-zero count is the toggle not having removed its buttons — **off is
@@ -412,11 +414,17 @@ Two lines of the self-check output are assertions in disguise:
   is `dialog-information-symbolic`, the plain information mark; `help-about-symbolic` is the status
   bar's ⓘ and a second meaning for it is what the app's own icons exist to avoid. `hint=WxH` is the
   size the **first visible** hint was allocated, measured the way every other rectangle here is
-  (`gtk_widget_compute_bounds()`), and **16x16 is the reading a "much tinier" mark must keep**: the
-  class zeroes the outer `menubutton` node, its `button` subnode and the glyph, which is what a
-  `GtkMenuButton` needs (its measure ignores both `min-width` on the widget and a size request) — the
-  default 34x34 is the number to compare against. Hints inside a collapsed expander are skipped, so the
-  number is never a hidden widget's 0x0. `tour=` is `running`/`idle` with the plan's `steps=` and the
+  (`gtk_widget_compute_bounds()`), and **12x12 is the reading a "much tinier" mark must keep**: the
+  class zeroes the outer `menubutton` node and its `button` subnode (a `GtkMenuButton`'s measure
+  ignores both `min-width` on the widget and a size request), and the glyph is a third node *below*
+  the subnode — `menubutton > button > box > image`, read off the CSS node dump. The direct-grandchild
+  form `> button > image` matches **nothing** and silently leaves the glyph at its natural 16 px,
+  which is the 16x16 an earlier version shipped by mistake; and there is no lower floor to find
+  (the symbolic glyph renders at any request, measured down to 4 px), so 12 px is a legibility
+  choice. The default 34x34 is the number to compare against. A hint inside a collapsed expander's
+  *child* is skipped, so the number is never a hidden widget's 0x0 — but a hint on the expander's
+  *header* is in the widget tree and reads its real size while the block is collapsed (see the
+  `collapsed search:` entry below). `tour=` is `running`/`idle` with the plan's `steps=` and the
   current `step=`; `auto=1` is the first-run auto-start having fired *in this process* — the flag is
   `tour_seen` in `settings.toml`, so a second run against the same config directory reads `auto=0` —
   and `requested=1` is the **chooser's** tour having handed over (`Config::tour_pending`), which is
@@ -506,7 +514,7 @@ Two lines of the self-check output are assertions in disguise:
   the saved-source list and the waveforms page's action row; the form's `AdwEntryRow`s are *not*
   hosts (a row is not a box and its editor is internal, so a hint cannot join it as a sibling) and
   the connection fields are explained by their group's `description` instead. `hint=WxH` is the
-  same 16x16 the window's line reads: the button is `ui_impl::context_help_button()`, the one
+  same 12x12 the window's line reads: the button is `ui_impl::context_help_button()`, the one
   `udpscope-hint` affordance both windows draw.
 - `[sources] tour: first run -- auto_started=1 in the chooser` then
   `[sources] chooser tour: visible=1 steps=5 step=0` (stderr) — **a first run's tour starts in the
@@ -751,16 +759,16 @@ two also catch a row whose accelerator went missing. `settings=` must be a real
   touches anything: `auto_started=1 visible=1` is the tour that started itself, and the parenthetical is
   `settings.tour_seen` as the process found it — `tour_seen already set` with `auto=0` is the *second*
   run against the same config directory, which is the assertion that the flag persisted. Then:
-  - `[helpui] contextual on: hints=11 ids={events plot status cursors measures trigger trigger_advanced events_record signals signals_config window} hint=16x16` —
-    the eleven "(i)" affordances, by id, and the size the first visible one was allocated. Ten are the
-    window's own surfaces (three of them a specific control's row rather than a heading — see the
-    `help layer:` entry) and the eleventh is `math`, which is present only while the math editor
-    window is open; it reads 10 with the editor shut. **On a fresh config this reads `hints=0 ids={}`
+  - `[helpui] contextual on: hints=12 ids={events plot status cursors measures trigger trigger_advanced events_record trigger_search signals signals_config window} hint=12x12` —
+    the twelve "(i)" affordances, by id, and the size the first visible one was allocated. Eleven are
+    the window's own surfaces (four of them a specific control's row rather than a heading — see the
+    `help layer:` entry) and the twelfth is `math`, which is present only while the math editor
+    window is open; it reads 11 with the editor shut. **On a fresh config this reads `hints=0 ids={}`
     and `hint=0x0`**, because the layer is off by default; the example is the state after the row below
     was switched on, and a fresh run's `hints=0` beside a `settings.toml` with no `contextual_help`
-    key is the default being read rather than assumed. **`hint=16x16` is the "much tinier" assertion**
+    key is the default being read rather than assumed. **`hint=12x12` is the "much tinier" assertion**
     — the default menu-button mark is 34x34 (see `help layer:`), and anything near that is the class
-    not reaching the outer `menubutton` node.
+    not reaching the glyph's own node.
   - `[helpui] main view: rows=7 help_row=1` and one `[helpui] entry N '<label>' accel='<key>' order=O`
     per row of the **Help view** — `entry 0 'Back'` with no accelerator and then the four the submenu
     promises: `entry 1 'Keyboard shortcuts' accel='Ctrl+/'`, `entry 2 'Documentation' accel='F1'`,
@@ -771,10 +779,10 @@ two also catch a row whose accelerator went missing. `settings=` must be a real
     `toggle=` being the contextual-help row's check, which *is* `settings.contextual_help`. It reads `0`
     on a fresh config (the default) and `1` on one where the setting is on; the probe's next step drives
     it both ways, which is why the example here is the `1` side.
-  - `[helpui] toggle: off -> hints=0 ids={}; on -> hints=11 ids={…}; setting=on` — the toggle's effect
+  - `[helpui] toggle: off -> hints=0 ids={}; on -> hints=12 ids={…}; setting=on` — the toggle's effect
     read both ways through the row itself. **`hints=0` with `off` is the assertion**: off means the
     affordances are *gone*, not greyed, so anything else is a row that hid its buttons instead of
-    removing them. The count comes back to the same eleven, which is the other half — a toggle that
+    removing them. The count comes back to the same twelve, which is the other half — a toggle that
     removed and could not restore is a one-way switch.
   - `[helpui] tour started from the probe: visible=1 steps=5 step=0` — the tour started the way
     `Ctrl+T` starts it. `steps=5` is the plan: the table's five steps whose surface is on screen or
@@ -804,6 +812,13 @@ two also catch a row whose accelerator went missing. `settings=` must be a real
     rather than leaving them to find the mode. `trigger_panel`'s height differs between them (508 px in
     configuration mode against 72 locked — the body is replaced by the summary), which is the check
     that the mode really moved.
+  - `[helpui] collapsed search: expanded=0 mapped=1 mapped_header=1 hint=12x12` (the last step, in
+    configuration mode, after the figures line) — the search block's "(i)" read on the expander's
+    **header** with the block **collapsed**. **`expanded=0 mapped=1` is the assertion**: a hint on the
+    expander's own *child* is not in the widget-parent chain while the block is collapsed and would
+    read `mapped=0` (and `0x0`), which is exactly why the header box exists (`search_head` in
+    `src/ui/trigger-panel.ui`) and why the hint joins it as its last child. `mapped_header=` is the
+    header box beside it, and `hint=WxH` is the same 12x12 the layer's own line reads.
 - `[toursurface] …` (stderr, `UDPSCOPE_PROBE_TOUR_SURFACE_MS`) — a stop that stands on a page it is
   not on, entered from the page it is not on. It puts the sidebar on **Measure**, starts the window's
   tour, and walks it a stop per tick (400 ms), because a stack allocates the new page's widgets on