LightSys Code-a-Thon 2026 Upgrades to API 36

[GroveOfGraves]

Please refer to the README of our fork for the full details of our contributions. It was a privilege to get to work on this project!

• Andrew Quick
• Eli Payton
• Gavin Montgomery

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This change is 

[devin-ai-integration]

Devin Review found 5 potential issues.

View 8 additional findings in Devin Review.

[devin-ai-integration]

🔴 NextButton arrow Path never reset, causing visual corruption on redraw

In NextButton.onDraw(), the arrow field is a reusable Path instance (line 41), but arrow.reset() is never called before new path segments are added at lines 57-64. Each call to onDraw() appends new line segments to the existing path, causing the shape to accumulate garbage and become visually corrupted over successive redraws. By contrast, PlayButton.onDraw() (PlayButton.java:45) correctly calls arrow.reset() before building its shape.

Suggested change

	arrow.moveTo(midX + thick / 2, deltaY); // upper right corner of stem
	arrow.lineTo(midX - thick / 2, deltaY); // upper left corner of stem
	arrow.lineTo(midX - thick / 2, stemY); // left junction of stem and arrow
	arrow.lineTo(deltaX, stemY); // left point of arrow
	arrow.lineTo(size/2 + deltaX, size + deltaY); // tip of arrow
	arrow.lineTo(size + deltaX, stemY); // right point of arrow
	arrow.lineTo(midX + thick / 2, stemY); // right junction of stem and arrow
	arrow.lineTo(midX + thick / 2, deltaY); // back to start
	arrow.reset();
	arrow.moveTo(midX + thick / 2, deltaY); // upper right corner of stem
	arrow.lineTo(midX - thick / 2, deltaY); // upper left corner of stem
	arrow.lineTo(midX - thick / 2, stemY); // left junction of stem and arrow
	arrow.lineTo(deltaX, stemY); // left point of arrow
	arrow.lineTo(size/2 + deltaX, size + deltaY); // tip of arrow
	arrow.lineTo(size + deltaX, stemY); // right point of arrow
	arrow.lineTo(midX + thick / 2, stemY); // right junction of stem and arrow
	arrow.lineTo(midX + thick / 2, deltaY); // back to start

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[devin-ai-integration]

🔴 RealFileSystem.getDirectories crashes with NPE when directory doesn't exist

Objects.requireNonNull(directory.listFiles()) at line 44 will throw a NullPointerException if the directory doesn't exist or the path doesn't point to a directory, because File.listFiles() returns null in those cases. The old code simply iterated the array directly (which also would have thrown NPE, but the new code explicitly adds requireNonNull making the crash intentional). This method is called from ServiceLocator.getScriptProvider() and MainActivity.getProjectRootDirectories(), where the path may not yet exist (e.g., before first sync).

Suggested change

	for (File file : Objects.requireNonNull(directory.listFiles())){
	File[] files = directory.listFiles();
	if (files == null) return result;
	for (File file : files){

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[devin-ai-integration]

🔴 RecordActivity._recordingFilePath initialized to null instead of empty string, causing NPE

The field _recordingFilePath is declared without initialization at line 84 (String _recordingFilePath;), defaulting to null. The old code initialized it to "" (String _recordingFilePath = "";). If _lineCount is 0 (e.g., empty chapter), setActiveLine() is never called (line 173-174: if (_lineCount > 0) setActiveLine(_activeLine)), so _recordingFilePath remains null. If the user then touches the record button, startWaveRecorder() calls new File(_recordingFilePath) at line 342, which throws NPE.

Suggested change

	String _recordingFilePath;
	String _recordingFilePath = "";

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[devin-ai-integration]

🔴 AcceptFileHandler corrupts binary file uploads by converting through UTF-8 String

When NanoHTTPD provides raw POST data as a string (the else branch at line 83-86), binary file content (e.g., .wav audio files) is written via contentOrPath.getBytes(StandardCharsets.UTF_8). This round-trips binary data through a Java String, which corrupts non-UTF-8 byte sequences. The original Apache HTTP handler used EntityUtils.toByteArray(entity) which preserved raw bytes. For small binary uploads that NanoHTTPD stores directly as a string (rather than saving to a temp file), the audio data will be silently corrupted during sync.

Prompt for agents

In AcceptFileHandler.java, lines 83-86, when NanoHTTPD stores POST body content directly as a string rather than a temp file path, the code writes it via contentOrPath.getBytes(StandardCharsets.UTF_8). This corrupts binary data like .wav files. The fix should ensure binary data is preserved. Consider: (1) Checking the Content-Type header to distinguish binary uploads, (2) Using NanoHTTPD's temp file mechanism which stores large uploads as files (the isPath branch already handles this), (3) For the raw string case, consider whether binary content can actually reach this branch, and if so, store it differently. The key issue is that NanoHTTPD's parseBody may put binary content through String encoding. You may need to configure NanoHTTPD's tmpdir and ensure all binary uploads go through the temp-file path.

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[devin-ai-integration]

🔴 SyncActivity uses startService() instead of startForegroundService() on Android 8+

In SyncActivity.startSyncServer() at line 145, startService(serviceIntent) is called. On Android 8.0+ (API 26+), if the app is in the background, startService() will throw an IllegalStateException for background services. Since SyncService.onStartCommand() calls startForeground(), it should be started via startForegroundService() (or ContextCompat.startForegroundService()) on API 26+ to comply with Android's background execution limits. Although the activity is likely in the foreground when this is called, edge cases (e.g., rapid permission dialog interactions) could cause the service start to fail.

Suggested change

	Intent serviceIntent = new Intent(this, SyncService.class);
	startService(serviceIntent);
	Intent serviceIntent = new Intent(this, SyncService.class);
	ContextCompat.startForegroundService(this, serviceIntent);

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