feat(gallery): add the ABC entry keypad

The kit entered digits three ways and text no way at all, so the panels that need a WiFi password had nothing to reach for. R57 takes free alphanumeric text. A-Z is laid out alphabetically rather than QWERTY, the industrial convention wherever the operator isn't assumed to touch-type, and what makes this a faceplate instead of a keyboard.

I followed two reference plates and departed from both, arguing each departure at its site. Their letters are blue and the kit has no blue control colour, so letters take the standard pale cap and digits a darker one: the photos' two-tone grouping without the foreign hue. Letters sit left and digits right so the alphabet reads down one unbroken block. With the digits on the left it stops column-aligning with itself halfway down.

DEL is new, because without a backspace one mistyped character costs the whole entry. It sits beside the digits in amber while CLR is exiled to the corner in red. DEL is constant and costs a character, CLR is rare and costs everything, so the safe key gets the good spot and the colour grades the cost before the legend is read. CANCEL is gone: on a plate that is the whole terminal it has a transaction to abandon, but here it did exactly what CLR does.

The window draws spaces as ␣. SVG collapses whitespace, and past the truncation boundary there are no pad dots left for a space to displace, so SPACE was a keypress with no feedback at all. The buffer keeps the real character.

1 files changed, 11 insertions, 0 deletions

diff --git a/docs/prototypes/panel-widget-gallery.html b/docs/prototypes/panel-widget-gallery.html
index 007b4cd..455b0ff 100644
--- a/docs/prototypes/panel-widget-gallery.html
+++ b/docs/prototypes/panel-widget-gallery.html
@@ -684,6 +684,14 @@ const INFO={
   origin:'PDP-11/70 and IMSAI front panels.',difficulty:'Intuitive to watch, expert to read.',
   prefer:'A spinner says busy; blinkenlights say HOW busy and with what rhythm.',
   period:'1965-80 minicomputer era; the icon of computing at work.'},
+'R57':{input:'Click keys to type; DEL takes back one character, CLR wipes the lot, ENT commits. Click-only, so it ports to Emacs unchanged.',
+  solves:'Free alphanumeric text on a panel that has no keyboard — the one job the rest of the kit cannot do.',
+  use:'Specialty. Shines where a panel must accept a string it could not know in advance: a passphrase, an SSID, a callsign, a label.',
+  limits:'Slow by design — a 20-character passphrase is 20 clicks. Any real keyboard beats it for volume; this is for panels that have none.',
+  origin:'Fleet, kiosk and access-control keypads — a membrane plate for the colour-coded function keys, a stainless one for the letters-left layout and the backspace.',
+  difficulty:'Intuitive to use, tedious past a few words.',
+  prefer:'Text is genuinely unbounded. R16 is the digits-only sibling and is faster where the alphabet is not needed.',
+  ref:'../../working/retro-stereo-widgets/references/2026-07-16-abc-keypad-membrane-color.png'},
 'R56':{input:'Drag the left half for temperature, the right for humidity. Drag-only, two surfaces.',
   solves:'A categorical verdict from two values — the crossing point falls into a printed judgment.',
   use:'Common on weather stations and comfort meters. Shines when the pair only matters as a combined condition: comfort, safe-operating region, duty envelope.',
@@ -1341,6 +1349,9 @@ card(C,'R50','Two-hand safety control',
 card(C,'R51','Voice-loop keyset',
   (st,rd)=>GW.voiceLoop(st,{onChange:(v,t)=>rd(t)}),
   '<b>attention management, not selection.</b> Each loop is independent: click to monitor (green bar, flickering with activity), again to talk (amber, exclusive — one voice out), again to drop. Flight controllers ran a dozen of these at once. After a mission-control comm keyset.');
+card(C,'R57','ABC entry keypad',
+  (st,rd)=>GW.abcKeypad(st,{onChange:(v,t)=>rd(t)}),
+  '<b>letters on a faceplate.</b> A-Z laid out alphabetically, not QWERTY — the industrial convention wherever the operator is not assumed to touch-type. Type into the window; DEL takes back one character, CLR wipes the lot, ENT commits. R16 enters digits; this is its alphanumeric sibling, and the only card in the kit that takes free text. After fleet and kiosk keypads: the membrane plate\'s colour-coded CLR / ENT, the stainless plate\'s letters-left arrangement and its backspace. Its CANCEL is dropped — that plate is a whole terminal with a transaction to abandon, where this is one control in a panel that owns its own dismiss.');
 
 /* ============ METERS & GAUGES ============ */
 const M=$('meters');