diff --git a/fizarrita/package.json b/fizarrita/package.json
index a39bba6..ae2a597 100644
--- a/fizarrita/package.json
+++ b/fizarrita/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@fideus-labs/fizarrita",
-  "version": "1.2.0",
+  "version": "1.3.0",
   "description": "Worker-pool-accelerated get/set for zarrita.js — offloads codec encode/decode to Web Workers.",
   "type": "module",
   "main": "./dist/index.js",
@@ -13,6 +13,18 @@
     "./codec-worker": {
       "types": "./dist/codec-worker.d.ts",
       "import": "./dist/codec-worker.js"
+    },
+    "./internals/codec-pipeline": {
+      "types": "./dist/internals/codec-pipeline.d.ts",
+      "import": "./dist/internals/codec-pipeline.js"
+    },
+    "./internals/setter": {
+      "types": "./dist/internals/setter.d.ts",
+      "import": "./dist/internals/setter.js"
+    },
+    "./internals/util": {
+      "types": "./dist/internals/util.d.ts",
+      "import": "./dist/internals/util.js"
     }
   },
   "files": [
diff --git a/fizarrita/src/get-worker.ts b/fizarrita/src/get-worker.ts
index 543c3a1..cd1684e 100644
--- a/fizarrita/src/get-worker.ts
+++ b/fizarrita/src/get-worker.ts
@@ -35,7 +35,7 @@ import { workerDecode, workerDecodeInto, getMetaId } from './worker-rpc.js'
  * Default URL for the codec worker. Uses `import.meta.url` to resolve
  * relative to this module.
  */
-const DEFAULT_WORKER_URL = new URL('./codec-worker.js', import.meta.url)
+export const DEFAULT_WORKER_URL = new URL('./codec-worker.js', import.meta.url)
 
 /** Shared TextDecoder instance. */
 const decoder = new TextDecoder()
@@ -54,14 +54,14 @@ const NULL_CACHE: ChunkCache = {
 const storeIdMap = new WeakMap<object, number>()
 let storeIdCounter = 0
 
-function getStoreId(store: Readable): string {
+export function getStoreId(store: Readable): string {
   if (!storeIdMap.has(store)) {
     storeIdMap.set(store, storeIdCounter++)
   }
   return `store_${storeIdMap.get(store)}`
 }
 
-function createCacheKey<D extends DataType, Store extends Readable>(
+export function createCacheKey<D extends DataType, Store extends Readable>(
   arr: ZarrArray<D, Store>,
   encodeChunkKey: (chunk_coords: number[]) => string,
   chunk_coords: number[],
@@ -75,13 +75,13 @@ function createCacheKey<D extends DataType, Store extends Readable>(
 // Unified metadata reader — reads zarr.json once, returns everything needed
 // ---------------------------------------------------------------------------
 
-interface ArrayMetadata {
+export interface ArrayMetadata {
   codecMeta: CodecChunkMeta
   encodeChunkKey: (chunk_coords: number[]) => string
   fillValue: Scalar<DataType> | null
 }
 
-async function readArrayMetadata<D extends DataType, Store extends Readable>(
+export async function readArrayMetadata<D extends DataType, Store extends Readable>(
   arr: ZarrArray<D, Store>,
 ): Promise<ArrayMetadata> {
   const store = arr.store
@@ -526,7 +526,7 @@ async function validateCandidateChunkShape<D extends DataType, Store extends Rea
  * Returns the corrected chunk shape, or the metadata chunk shape if no
  * correction is needed or possible.
  */
-async function probeActualChunkShape<D extends DataType, Store extends Readable>(
+export async function probeActualChunkShape<D extends DataType, Store extends Readable>(
   arr: ZarrArray<D, Store>,
   encodeChunkKey: (chunk_coords: number[]) => string,
   codecMeta: CodecChunkMeta,
diff --git a/fizarrita/src/index.ts b/fizarrita/src/index.ts
index a7c1dc4..e563acd 100644
--- a/fizarrita/src/index.ts
+++ b/fizarrita/src/index.ts
@@ -6,11 +6,46 @@
  * WorkerPool with bounded concurrency.
  */
 
-export { getWorker, readZstdFrameContentSize, readBloscFrameContentSize, inferChunkShape } from './get-worker.js'
+export {
+  getWorker,
+  readZstdFrameContentSize,
+  readBloscFrameContentSize,
+  inferChunkShape,
+  DEFAULT_WORKER_URL,
+  readArrayMetadata,
+  probeActualChunkShape,
+  createCacheKey,
+  getStoreId,
+} from './get-worker.js'
+export type { ArrayMetadata } from './get-worker.js'
 export { setWorker } from './set-worker.js'
 export type {
   GetWorkerOptions,
   SetWorkerOptions,
   CodecChunkMeta,
   ChunkCache,
+  Projection,
+  Indices,
 } from './types.js'
+
+// Internals — exported for building custom workers that extend the codec worker
+export { create_codec_pipeline } from './internals/codec-pipeline.js'
+export {
+  get_ctr,
+  get_strides,
+  create_chunk_key_encoder,
+  createBuffer,
+  assertSharedArrayBufferAvailable,
+} from './internals/util.js'
+export type { ChunkKeyEncoding } from './internals/util.js'
+export { setter, compat_chunk, set_from_chunk_binary } from './internals/setter.js'
+export {
+  BasicIndexer,
+  normalize_selection,
+  slice,
+  slice_indices,
+} from './internals/indexer.js'
+export type { ChunkProjection, IndexerProjection } from './internals/indexer.js'
+
+// Worker RPC helpers — for composing custom workers
+export { workerDecode, workerDecodeInto, workerEncode, getMetaId } from './worker-rpc.js'