diff --git a/eslint.config.mjs b/eslint.config.mjs
index 4f9053d..dcc3101 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -48,6 +48,7 @@ export default tseslint.config(
 			'eslint.config.mjs',
 			'docs/.vitepress/cache',
 			'test/public',
+			'testfiles_temp'
 		]
 	}
 );
diff --git a/hls-sketch.ts b/hls-sketch.ts
deleted file mode 100644
index 34f73c5..0000000
--- a/hls-sketch.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-const hlsInput = new ManifestInput({
-	source: new UrlSource('https://example.com/playlist.m3u8'),
-	formats: [HLS],
-});
-
-const variants = await hlsInput.getVariants();
-const bestVariant = await hlsInput.getPrimaryVariant();
-const qualityVariant = await hlsInput.getVariantFor('1080p'); // In spirit
-
-bestVariant.tracks; // ?
-bestVariant.bitrate; // ?
-bestVariant.isLive(); // ?
-
-const input = variant.toInput(); // => Input
-const segments = variant.getSegments(); // => Segments[]?
-
-const segment = variant.getFirstSegment();
-segment.path; // => string (for example 'segment1.ts')
-segment.timestamp; // => 10
-segment.duration; // 5
-segment.toInput(); // => Input
diff --git a/src/custom-coder.ts b/src/custom-coder.ts
index e2a558d..3661d3a 100644
--- a/src/custom-coder.ts
+++ b/src/custom-coder.ts
@@ -7,6 +7,8 @@
  */
 
 import { AudioCodec, VideoCodec } from './codec';
+import { canDecodeAudioMemo, canDecodeVideoMemo } from './decode';
+import { canEncodeAudioMemo, canEncodeVideoMemo } from './encode';
 import { MaybePromise } from './misc';
 import { EncodedPacket } from './packet';
 import { AudioSample, VideoSample } from './sample';
@@ -152,6 +154,7 @@ export const registerDecoder = (decoder: typeof CustomVideoDecoder | typeof Cust
 		}
 
 		customVideoDecoders.push(casted);
+		canDecodeVideoMemo.clear();
 	} else if (decoder.prototype instanceof CustomAudioDecoder) {
 		const casted = decoder as typeof CustomAudioDecoder;
 
@@ -161,6 +164,7 @@ export const registerDecoder = (decoder: typeof CustomVideoDecoder | typeof Cust
 		}
 
 		customAudioDecoders.push(casted);
+		canDecodeAudioMemo.clear();
 	} else {
 		throw new TypeError('Decoder must be a CustomVideoDecoder or CustomAudioDecoder.');
 	}
@@ -182,6 +186,7 @@ export const registerEncoder = (encoder: typeof CustomVideoEncoder | typeof Cust
 		}
 
 		customVideoEncoders.push(casted);
+		canEncodeVideoMemo.clear();
 	} else if (encoder.prototype instanceof CustomAudioEncoder) {
 		const casted = encoder as typeof CustomAudioEncoder;
 
@@ -191,6 +196,7 @@ export const registerEncoder = (encoder: typeof CustomVideoEncoder | typeof Cust
 		}
 
 		customAudioEncoders.push(casted);
+		canEncodeAudioMemo.clear();
 	} else {
 		throw new TypeError('Encoder must be a CustomVideoEncoder or CustomAudioEncoder.');
 	}
diff --git a/src/decode.ts b/src/decode.ts
index e301af1..ca1fb8c 100644
--- a/src/decode.ts
+++ b/src/decode.ts
@@ -22,8 +22,8 @@ import {
 import { customAudioDecoders, customVideoDecoders } from './custom-coder';
 import { isAllowSharedBufferSource, SetOptional } from './misc';
 
-const canDecodeVideoMemo = new Map<string, Promise<boolean>>();
-const canDecodeAudioMemo = new Map<string, Promise<boolean>>();
+export const canDecodeVideoMemo = new Map<string, Promise<boolean>>();
+export const canDecodeAudioMemo = new Map<string, Promise<boolean>>();
 
 const validateVideoDecodingConfig = (codec: VideoCodec, options: SetOptional<VideoDecoderConfig, 'codec'>) => {
 	if (!options || typeof options !== 'object') {
diff --git a/src/encode.ts b/src/encode.ts
index b3048c9..5de3094 100644
--- a/src/encode.ts
+++ b/src/encode.ts
@@ -26,8 +26,8 @@ import { isFirefox, MaybePromise, Rotation } from './misc';
 import { EncodedPacket } from './packet';
 import { AudioSample, CropRectangle, validateCropRectangle, VideoSample } from './sample';
 
-const canEncodeVideoMemo = new Map<string, Promise<boolean>>();
-const canEncodeAudioMemo = new Map<string, Promise<boolean>>();
+export const canEncodeVideoMemo = new Map<string, Promise<boolean>>();
+export const canEncodeAudioMemo = new Map<string, Promise<boolean>>();
 
 /**
  * Configuration object that controls video encoding. Can be used to set codec, quality, and more.
diff --git a/src/flac/flac-muxer.ts b/src/flac/flac-muxer.ts
index 23db6de..e3bcb5a 100644
--- a/src/flac/flac-muxer.ts
+++ b/src/flac/flac-muxer.ts
@@ -49,16 +49,16 @@ export class FlacMuxer extends Muxer {
 		super(output);
 
 		this.format = format;
-
-		if (this.format._options.appendOnly) {
-			this.writer.ensureMonotonicity();
-		}
 	}
 
 	async start() {
 		const release = await this.mutex.acquire();
 
 		this.writer = await this.output._getRootWriter();
+		if (this.format._options.appendOnly) {
+			this.writer.ensureMonotonicity();
+		}
+
 		this.writer.write(FLAC_HEADER);
 
 		release();
diff --git a/src/hls/hls-demuxer.ts b/src/hls/hls-demuxer.ts
index 503b0c1..015d4fd 100644
--- a/src/hls/hls-demuxer.ts
+++ b/src/hls/hls-demuxer.ts
@@ -1,3 +1,11 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
 import { AUDIO_CODECS, AudioCodec, inferCodecFromCodecString, MediaCodec, VIDEO_CODECS, VideoCodec } from '../codec';
 import { Demuxer, DurationMetadataRequestOptions } from '../demuxer';
 import { Input } from '../input';
diff --git a/src/hls/hls-misc.ts b/src/hls/hls-misc.ts
index dce2e15..db583c3 100644
--- a/src/hls/hls-misc.ts
+++ b/src/hls/hls-misc.ts
@@ -1,3 +1,11 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
 export const canIgnoreLine = (line: string) => line.length === 0 || (line.startsWith('#') && !line.startsWith('#EXT'));
 
 export class AttributeList {
diff --git a/src/hls/hls-muxer.ts b/src/hls/hls-muxer.ts
index a38792b..7c74b43 100644
--- a/src/hls/hls-muxer.ts
+++ b/src/hls/hls-muxer.ts
@@ -1,3 +1,11 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
 import { MediaCodec, validateAudioChunkMetadata, validateVideoChunkMetadata } from '../codec';
 import { EncodedAudioPacketSource, EncodedVideoPacketSource } from '../media-source';
 import { arrayArgmax, assert, findLastIndex, joinPaths, textEncoder, toArray, UNDETERMINED_LANGUAGE } from '../misc';
diff --git a/src/hls/hls-segmented-input.ts b/src/hls/hls-segmented-input.ts
index 7eb7e09..80ef1d8 100644
--- a/src/hls/hls-segmented-input.ts
+++ b/src/hls/hls-segmented-input.ts
@@ -1,3 +1,11 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
 import { AES_128_BLOCK_SIZE, createAes128CbcDecryptStream } from '../aes';
 import { ENCRYPTION_KEY_CACHE_GROUP, Input } from '../input';
 import { Segment, SegmentedInput, SegmentRetrievalOptions } from '../segmented-input';
diff --git a/src/resample.ts b/src/resample.ts
index 19c4606..727492d 100644
--- a/src/resample.ts
+++ b/src/resample.ts
@@ -1,3 +1,11 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
 import { assert } from './misc';
 import { AudioSample } from './sample';
 
diff --git a/test/browser/flac.test.ts b/test/browser/flac.test.ts
index ddc065b..ef57adb 100644
--- a/test/browser/flac.test.ts
+++ b/test/browser/flac.test.ts
@@ -52,7 +52,7 @@ test('can convert a .flac to .wav', async () => {
 	assert(outputTrack);
 
 	const duration = await outputTrack.computeDuration();
-	expect(duration).toBe(19.71428571428571);
+	expect(duration).toBe(19.714285714285715);
 	const tags = await outputAsInput.getMetadataTags();
 	expect(tags.raw).toEqual({
 		IART: 'Samples Files',
diff --git a/test/node/disposition.test.ts b/test/node/disposition.test.ts
index 18e0b2e..faa4871 100644
--- a/test/node/disposition.test.ts
+++ b/test/node/disposition.test.ts
@@ -41,6 +41,7 @@ test('Default track disposition', async () => {
 		original: false,
 		hearingImpaired: false,
 		visuallyImpaired: false,
+		primary: false,
 		commentary: false,
 	});
 });
@@ -87,6 +88,7 @@ test('Customized track disposition', async () => {
 		original: true,
 		hearingImpaired: true,
 		visuallyImpaired: true,
+		primary: false,
 		commentary: true,
 	});
 });
diff --git a/test/node/flac.test.ts b/test/node/flac.test.ts
index f31e19c..f00befd 100644
--- a/test/node/flac.test.ts
+++ b/test/node/flac.test.ts
@@ -21,7 +21,7 @@ test('can loop over all samples', async () => {
 
 	const track = await input.getPrimaryAudioTrack();
 	assert(track);
-	expect(await track.computeDuration()).toEqual(19.71428571428571);
+	expect(await track.computeDuration()).toEqual(19.714285714285715);
 	expect(await track.getDecoderConfig()).toEqual({
 		codec: 'flac',
 		numberOfChannels: 2,