diff --git a/build.sh b/build.sh
index bd01dc9..a0633a7 100755
--- a/build.sh
+++ b/build.sh
@@ -15,9 +15,9 @@ mkdir -p dist
 # Precompile the PM_K-1 CircuitPython firmware to .mpy. CircuitPython compiles a ~56KB .py at boot,
 # which fragments the heap and OOMs on the RP2040; a precompiled .mpy loads without compiling. Needs
 # Adafruit's mpy-cross matching the device's CircuitPython (10.2.1) -> emits CircuitPython mpy v6.
-MPYC="tools/mpy-cross"
+MPYC="$PWD/tools/mpy-cross"; ROOT="$PWD"
 [[ -x "$MPYC" ]] || { echo "error: $MPYC missing (Adafruit mpy-cross for CircuitPython 10.2.1)" >&2; exit 1; }
-"$MPYC" pico-cp/app.py -o dist/app.mpy
+( cd pico-cp && "$MPYC" app.py -o "$ROOT/dist/app.mpy" )   # compile from pico-cp/ so tracebacks read "app.py"
 echo "precompiled dist/app.mpy ($(stat -c%s dist/app.mpy) bytes <- $(stat -c%s pico-cp/app.py) source)"
 
 python3 - <<'PY'
diff --git a/pico-cp/__pycache__/app.cpython-312.pyc b/pico-cp/__pycache__/app.cpython-312.pyc
index 511ca05..0d4042b 100644
Binary files a/pico-cp/__pycache__/app.cpython-312.pyc and b/pico-cp/__pycache__/app.cpython-312.pyc differ
diff --git a/pico-cp/app.py b/pico-cp/app.py
index d0e97ac..dbc1287 100644
--- a/pico-cp/app.py
+++ b/pico-cp/app.py
@@ -18,7 +18,7 @@
 
 import board, busio, digitalio, analogio, pwmio, displayio, vectorio, time, json, gc, os, supervisor
 supervisor.runtime.autoreload = False   # we write our own files (log + pushed programs); never self-restart
-APP_VERSION = "0.0.10"                   # firmware version (the A/B updater pushes/compares this)
+APP_VERSION = "0.0.11"                   # firmware version (the A/B updater pushes/compares this)
 try:
     import rtc                           # set from the editor's clock SysEx so the log has real timestamps
 except ImportError:
@@ -292,8 +292,9 @@ def lane_to_str(L):                                     # serialize a lane back
     if L['mute']: s += '!'
     return s
 
-def _slkey(t):                          # normalise a title for built-in/user de-duplication
-    return "".join(c.lower() for c in t if c.isalnum())
+_ALNUM = "abcdefghijklmnopqrstuvwxyz0123456789"
+def _slkey(t):                          # normalise a title for built-in/user de-dup (no str.isalnum on CircuitPython)
+    return "".join(c for c in t.lower() if c in _ALNUM)
 def load_user_setlists():
     # User playlists from /programs.json (pushed by the editor). New {setlists:[{title,programs:[..]}]} form,
     # or the old flat {programs:[..]} (one list). Built-ins are baked in BUILTIN_SETLISTS, never here.