diff --git a/slab/menuband-win/menuband.c b/slab/menuband-win/menuband.c
index d898f2b6d7..aa1e34aad8 100644
--- a/slab/menuband-win/menuband.c
+++ b/slab/menuband-win/menuband.c
@@ -51,6 +51,10 @@ static const GUID  MB_SUBTYPE_IEEE_FLOAT       = {0x00000003,0x0000,0x0010,{0x80
 
 static void mb_log(const wchar_t *fmt, ...);
 static void setting_set(const wchar_t *name, DWORD v);
+static void unlatch(HWND hwnd, int all);
+static void latch_note(int midi);
+static int g_enterLatch;
+static int g_latched[128];           // Enter-latched notes (drawn lit, sound until unlatched)
 static const wchar_t *GM_NAMES[128];
 static volatile LONG g_dbgNoteOns;
 
@@ -689,7 +693,7 @@ static void paint(void) {
             RECT kr = white_rect(i); kr.left += dx; kr.right += dx;
             if (kr.right < g_clipL || kr.left >= g_clipR) continue;
             RGB8 hi = whiteHi, lo = whiteLo;
-            int lit = m >= 0 && m < 128 && g_lit[m] > 0;
+            int lit = m >= 0 && m < 128 && (g_lit[m] > 0 || g_latched[m]);
             if (lit) { RGB8 l = blend(CHROMA[mv], black, 0.22); hi = l; lo = l; }
             else if (m == g_hoverMidi && !sliding) { hi = blend(whiteHi, white, 0.12); lo = blend(whiteLo, white, 0.12); }
             fill(kr, hi, lo, 1.0);
@@ -701,7 +705,7 @@ static void paint(void) {
             RECT br = black_rect(g_blackMidi[i]); br.left += dx; br.right += dx;
             if (br.right < g_clipL || br.left >= g_clipR) continue;
             RGB8 hi = blackHi, lo = blackLo;
-            if (m >= 0 && m < 128 && g_lit[m] > 0) { hi = white; lo = blend(white, blackHi, 0.4); }
+            if (m >= 0 && m < 128 && (g_lit[m] > 0 || g_latched[m])) { hi = white; lo = blend(white, blackHi, 0.4); }
             else if (m == g_hoverMidi && !sliding) { hi = blend(blackHi, white, 0.18); lo = blend(blackLo, white, 0.18); }
             fill(br, hi, lo, 1.0);
         }
@@ -802,6 +806,8 @@ static void build_keymap(void) {
 #define WM_CTRLTRIPLE (WM_APP + 6)
 #define WM_PEDAL (WM_APP + 7)
 #define WM_SURF (WM_APP + 8)
+#define WM_LATCH (WM_APP + 9)
+#define WM_UNLATCH (WM_APP + 10)
 static DWORD g_ctrlTapTimes[3]; static int g_ctrlTaps = 0; static int g_ctrlSolo = 0;
 
 static LRESULT CALLBACK ll_keyboard(int code, WPARAM wp, LPARAM lp) {
@@ -828,6 +834,8 @@ static LRESULT CALLBACK ll_keyboard(int code, WPARAM wp, LPARAM lp) {
         KBDLLHOOKSTRUCT *k = (KBDLLHOOKSTRUCT *)lp;
         int down = (wp == WM_KEYDOWN || wp == WM_SYSKEYDOWN);
         if (k->vkCode == VK_LSHIFT || k->vkCode == VK_RSHIFT || k->vkCode == VK_CAPITAL) { PostMessageW(g_strip, WM_PEDAL, 0, 0); return CallNextHookEx(g_hook, code, wp, lp); }
+        if (k->vkCode == VK_RETURN) { PostMessageW(g_strip, WM_LATCH, down, 0); return 1; }
+        if (k->vkCode == VK_BACK) { if (down && !(k->flags & LLKHF_UP)) PostMessageW(g_strip, WM_UNLATCH, (GetAsyncKeyState(VK_SHIFT) & 0x8000) ? 1 : 0, 0); return 1; }
         if (k->vkCode == VK_LEFT || k->vkCode == VK_RIGHT || k->vkCode == VK_UP || k->vkCode == VK_DOWN) {
             if (down) PostMessageW(g_strip, WM_SURF, k->vkCode == VK_RIGHT ? 1 : k->vkCode == VK_LEFT ? (WPARAM)-1 : k->vkCode == VK_UP ? 8 : (WPARAM)-8, 0);
             return 1;
@@ -849,6 +857,7 @@ static LRESULT CALLBACK ll_keyboard(int code, WPARAM wp, LPARAM lp) {
 }
 
 static int g_sustained[128];       // note released while its pedal was down; sounds until pedal-up
+static int g_latchOrder[128], g_latchCount = 0;   // Enter-latch order
 static int pedal_holds(int midi) {
     int caps = (GetKeyState(VK_CAPITAL) & 1) != 0;
     int lshift = (GetAsyncKeyState(VK_LSHIFT) & 0x8000) != 0, rshift = (GetAsyncKeyState(VK_RSHIFT) & 0x8000) != 0;
@@ -858,13 +867,27 @@ static int pedal_holds(int midi) {
 }
 static void lit_on(HWND hwnd, int midi, int vel) {
     if (midi < 0 || midi > 127) return;
-    if (g_sustained[midi]) { g_sustained[midi] = 0; play_off(midi); g_lit[midi] = 0; }   // retrigger a pedalled note
+    if (g_sustained[midi] || g_latched[midi]) { g_sustained[midi] = 0; g_latched[midi] = 0; play_off(midi); g_lit[midi] = 0; }   // retrigger a held note
     if (g_lit[midi]++ == 0) play_on(midi, vel);
     push_frame(hwnd);
 }
 static void lit_off(HWND hwnd, int midi) {
     if (midi < 0 || midi > 127 || g_lit[midi] == 0) return;
-    if (--g_lit[midi] == 0) { if (pedal_holds(midi)) g_sustained[midi] = 1; else play_off(midi); }
+    if (--g_lit[midi] == 0) { if (g_enterLatch) latch_note(midi); else if (g_latched[midi]) { } else if (pedal_holds(midi)) g_sustained[midi] = 1; else play_off(midi); }
+    push_frame(hwnd);
+}
+// Enter-latch: while Return is held, a note you release stays on until
+// Backspace pops it (newest first) or Shift+Backspace clears them all.
+static void latch_note(int midi) {
+    if (g_latched[midi]) return;
+    g_latched[midi] = 1; if (g_latchCount < 128) g_latchOrder[g_latchCount++] = midi;
+}
+static void unlatch(HWND hwnd, int all) {
+    while (g_latchCount > 0) {
+        int m = g_latchOrder[--g_latchCount];
+        if (g_latched[m]) { g_latched[m] = 0; if (g_lit[m] == 0 && !g_sustained[m]) play_off(m); }
+        if (!all) break;
+    }
     push_frame(hwnd);
 }
 static void pedal_release(HWND hwnd) {
@@ -896,7 +919,7 @@ static void cue(HWND hwnd, int a, int b) { g_cueNotes[0] = a; g_cueNotes[1] = b;
 static void typing_set(HWND hwnd, int on) {
     if (on == g_typing) return;
     g_typing = on;
-    if (!on) release_typed(hwnd);
+    if (!on) { release_typed(hwnd); g_enterLatch = 0; unlatch(hwnd, 1); }
     g_pendingDigits[0] = 0;
     flash(on ? FOCUS_BLUE : STOP_RED);
     cue(hwnd, on ? 84 : 79, on ? 91 : 72);
@@ -1224,6 +1247,12 @@ static LRESULT CALLBACK wndproc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp) {
     case WM_PEDAL:
         pedal_release(hwnd);
         return 0;
+    case WM_LATCH:
+        g_enterLatch = (int)wp;
+        return 0;
+    case WM_UNLATCH:
+        unlatch(hwnd, (int)wp);
+        return 0;
     case WM_SURF: {
         // Arrow keys surf the instruments: ←/→ one program, ↑/↓ one family.
         int next = g_program + (int)(intptr_t)wp; if (next < 0) next += 128; if (next > 127) next -= 128;
diff --git a/toolchain/knot/heal-knot.sh b/toolchain/knot/heal-knot.sh
new file mode 100755
index 0000000000..6c95e35224
--- /dev/null
+++ b/toolchain/knot/heal-knot.sh
@@ -0,0 +1,83 @@
+#!/bin/bash
+# heal-knot.sh — stop knot.aesthetic.computer wedging every quarter hour.
+#
+# Diagnosis (2026-10-10): the knot's cgroup is capped at MemoryHigh=1536M, and
+# git-upload-pack for the multi-gigabyte core repo runs INSIDE that cgroup
+# (a full clone takes ~3 min and gigabytes of pack memory). memory.events
+# showed 213,905 "high" throttle events: once a clone is in flight the whole
+# cgroup crawls, including `knot keys` which sshd calls for every git auth,
+# so pushes hang and port 5555 stops answering. Not a leak — pack memory.
+#
+# Fix, applied as root over `ssh aesthetic-pds`:
+#   1. cap git's pack memory in the bare repos (pack.windowMemory etc.), so a
+#      clone of core costs a few hundred MB instead of gigabytes;
+#   2. loosen the cgroup to what the 3.9 GB box can spare;
+#   3. a watchdog timer that restarts knotserver when 5555 stops answering;
+#   4. Restart=always so a crash never leaves it down.
+# Run from a Mac:  bash toolchain/knot/heal-knot.sh
+set -euo pipefail
+ssh -o BatchMode=yes aesthetic-pds 'bash -s' <<'REMOTE'
+set -euo pipefail
+echo "== git pack memory caps on the bare repos"
+for r in /home/git/repositories/*/ /home/git/repositories/*/*/; do
+  [ -d "$r" ] || continue
+  if git -C "$r" rev-parse --is-bare-repository >/dev/null 2>&1; then
+    git -C "$r" config pack.threads 1
+    git -C "$r" config pack.windowMemory 128m
+    git -C "$r" config pack.deltaCacheSize 64m
+    git -C "$r" config pack.packSizeLimit 512m
+    git -C "$r" config core.packedGitWindowSize 32m
+    git -C "$r" config core.packedGitLimit 256m
+    git -C "$r" config core.bigFileThreshold 4m
+    chown git:git "$r/config" 2>/dev/null || true
+    echo "  capped $r"
+  fi
+done
+echo "== cgroup: more room, and Restart=always"
+mkdir -p /etc/systemd/system/knotserver.service.d
+cat > /etc/systemd/system/knotserver.service.d/at-upkeep-memory.conf <<'UNIT'
+[Service]
+Environment=GOMEMLIMIT=768MiB
+MemoryHigh=2600M
+MemoryMax=3200M
+Restart=always
+RestartSec=3
+UNIT
+echo "== watchdog: restart when port 5555 stops answering"
+cat > /usr/local/bin/knot-watchdog.sh <<'WD'
+#!/bin/bash
+code=$(curl -s -m 8 -o /dev/null -w "%{http_code}" http://127.0.0.1:5555/ || echo 000)
+if [ "$code" = "000" ]; then
+  logger -t knot-watchdog "port 5555 not answering (rss $(ps -o rss= -C knot | sort -n | tail -1 | tr -d ' ') kB); restarting knotserver"
+  systemctl restart knotserver.service
+fi
+WD
+chmod +x /usr/local/bin/knot-watchdog.sh
+cat > /etc/systemd/system/knot-watchdog.service <<'UNIT'
+[Unit]
+Description=Restart the knot when it stops answering
+[Service]
+Type=oneshot
+ExecStart=/usr/local/bin/knot-watchdog.sh
+UNIT
+cat > /etc/systemd/system/knot-watchdog.timer <<'UNIT'
+[Unit]
+Description=Knot health check every 30 s
+[Timer]
+OnBootSec=90
+OnUnitActiveSec=30
+AccuracySec=5
+[Install]
+WantedBy=timers.target
+UNIT
+systemctl daemon-reload
+systemctl enable --now knot-watchdog.timer
+systemctl restart knotserver.service
+sleep 6
+echo "== state"
+systemctl show knotserver -p MemoryHigh -p MemoryMax -p Restart | tr '\n' ' '; echo
+systemctl list-timers knot-watchdog.timer --no-pager | head -3
+curl -s -m 5 -o /dev/null -w "knot http=%{http_code}\n" http://127.0.0.1:5555/
+REMOTE
+echo "== from here"
+timeout 20 ssh -o BatchMode=yes -T git@knot.aesthetic.computer 2>&1 | head -1