fix(wasm): Fix Emscripten empty callback functions for pthreads builds

Emscripten with pthreads generates empty arrow functions `{}` for callback
paths it assumes won't be used. However, when registering HTML5 events from
the main browser thread, targetThread is 0 and the direct call path IS taken.

This fix post-processes the generated JS to replace empty callbacks with
actual dynCall invocations for:
- HTML5 event callbacks (dynCall_iiii) - 7 instances
- pthread entry points (dynCall_ii) - 1 instance
- Signal handlers (dynCall_vi) - 1 instance
- Async timers (dynCall_vi) - 1 instance

Also improves build logging to show completion status and exit code.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

scripts/common/inject-dyncall-shims.sh

@@ -112,3 +112,65 @@ mv "${JS_FILE}.tmp" "$JS_FILE"
 rm "$SHIM_FILE"
 
 echo "Successfully injected $SIG_COUNT dynCall shims into $JS_FILE"
+
+# Fix empty callback arrow functions generated by Emscripten with pthreads
+# When pthreads is enabled, Emscripten generates empty {} for some direct-call paths
+# because it assumes they won't be used. But they ARE used in certain cases.
+# The dynCall_* functions exist (generated above), we just need to call them.
+echo "Fixing empty callback arrow functions..."
+
+TOTAL_FIXED=0
+
+# Fix 1: HTML5 event callbacks (3 args) - signature iiii
+# Pattern: ((a1, a2, a3) => {})(eventTypeId, ...
+# Function pointer is 'callbackfunc' in these contexts
+COUNT_BEFORE=$(grep -c '((a1, a2, a3) => {})(eventTypeId,' "$JS_FILE" || true)
+if [ "$COUNT_BEFORE" -gt 0 ]; then
+    sed -i '' 's/((a1, a2, a3) => {})(eventTypeId,/((a1, a2, a3) => dynCall_iiii(callbackfunc, a1, a2, a3))(eventTypeId,/g' "$JS_FILE"
+    COUNT_AFTER=$(grep -c '((a1, a2, a3) => {})(eventTypeId,' "$JS_FILE" || true)
+    FIXED=$((COUNT_BEFORE - COUNT_AFTER))
+    echo "  Fixed $FIXED HTML5 event callback(s) (dynCall_iiii)"
+    TOTAL_FIXED=$((TOTAL_FIXED + FIXED))
+fi
+
+# Fix 2: invokeEntryPoint pthread entry (1 arg) - signature ii (returns pointer)
+# Pattern in invokeEntryPoint: var result = (a1 => {})(arg);
+# Function pointer is 'ptr'
+COUNT_BEFORE=$(grep -c 'var result = (a1 => {})(arg);' "$JS_FILE" || true)
+if [ "$COUNT_BEFORE" -gt 0 ]; then
+    sed -i '' 's/var result = (a1 => {})(arg);/var result = dynCall_ii(ptr, arg);/g' "$JS_FILE"
+    COUNT_AFTER=$(grep -c 'var result = (a1 => {})(arg);' "$JS_FILE" || true)
+    FIXED=$((COUNT_BEFORE - COUNT_AFTER))
+    echo "  Fixed $FIXED pthread entry callback(s) (dynCall_ii)"
+    TOTAL_FIXED=$((TOTAL_FIXED + FIXED))
+fi
+
+# Fix 3: ___call_sighandler (1 arg) - signature vi (void return)
+# Pattern: return (a1 => {})(sig);
+# Function pointer is 'fp'
+COUNT_BEFORE=$(grep -c 'return (a1 => {})(sig);' "$JS_FILE" || true)
+if [ "$COUNT_BEFORE" -gt 0 ]; then
+    sed -i '' 's/return (a1 => {})(sig);/return dynCall_vi(fp, sig);/g' "$JS_FILE"
+    COUNT_AFTER=$(grep -c 'return (a1 => {})(sig);' "$JS_FILE" || true)
+    FIXED=$((COUNT_BEFORE - COUNT_AFTER))
+    echo "  Fixed $FIXED signal handler callback(s) (dynCall_vi)"
+    TOTAL_FIXED=$((TOTAL_FIXED + FIXED))
+fi
+
+# Fix 4: _emscripten_async_call timer (1 arg) - signature vi (void return)
+# Pattern: var wrapper = () => (a1 => {})(arg);
+# Function pointer is 'func'
+COUNT_BEFORE=$(grep -c 'var wrapper = () => (a1 => {})(arg);' "$JS_FILE" || true)
+if [ "$COUNT_BEFORE" -gt 0 ]; then
+    sed -i '' 's/var wrapper = () => (a1 => {})(arg);/var wrapper = () => dynCall_vi(func, arg);/g' "$JS_FILE"
+    COUNT_AFTER=$(grep -c 'var wrapper = () => (a1 => {})(arg);' "$JS_FILE" || true)
+    FIXED=$((COUNT_BEFORE - COUNT_AFTER))
+    echo "  Fixed $FIXED async timer callback(s) (dynCall_vi)"
+    TOTAL_FIXED=$((TOTAL_FIXED + FIXED))
+fi
+
+if [ "$TOTAL_FIXED" -gt 0 ]; then
+    echo "Total: Fixed $TOTAL_FIXED empty callback(s)"
+else
+    echo "No empty callbacks found - nothing to fix"
+fi

scripts/common/logging.sh

@@ -41,8 +41,18 @@ mkdir -p "${_LOGS_DIR}"
 # Show log path before re-exec
 echo "Logging to: ${_LOG_FILE}"
 
-# Re-exec the calling script with output redirected
+# Run the calling script with output redirected
 # This is equivalent to: ./script.sh > logfile 2>&1
 # and reliably captures ALL output including docker compose TTY messages
 export KICAD_LOG_NESTED=1
-exec "${_CALLER_SCRIPT}" "$@" > "${_LOG_FILE}" 2>&1
+"${_CALLER_SCRIPT}" "$@" > "${_LOG_FILE}" 2>&1
+_EXIT_CODE=$?
+
+# Print completion message (this runs AFTER the script finishes)
+if [[ ${_EXIT_CODE} -eq 0 ]]; then
+    echo "Done. Log: ${_LOG_FILE}"
+else
+    echo "Failed (exit ${_EXIT_CODE}). Log: ${_LOG_FILE}"
+fi
+
+exit ${_EXIT_CODE}