diff --git a/README.md b/README.md
index 27c0b1c..68e2348 100644
--- a/README.md
+++ b/README.md
@@ -129,6 +129,88 @@ const demo = async blob => {
 }
 ```
 
+### Collecting UnixFS FileLinks
+
+You can optionally pass a unixFsFileLinkWriter stream to capture metadata for each link (useful for indexing or tracking layout information).
+
+```js
+import {
+  createWriter,
+  createFileWriter,
+} from '@ipld/unixfs'
+
+import { withMaxChunkSize } from '@ipld/unixfs/file/chunker/fixed'
+import { withWidth } from '@ipld/unixfs/file/layout/balanced'
+
+const defaultSettings = UnixFS.configure({
+  fileChunkEncoder: raw,
+  smallFileEncoder: raw,
+  chunker: withMaxChunkSize(1024 * 1024),
+  fileLayout: withWidth(1024),
+})
+
+/**
+ * @param {Blob} blob
+ * @returns {Promise<import('@vascosantos/unixfs').FileLink[]>}
+ */
+async function collectUnixFsFileLinks(blob) {
+  const fileLinks = []
+
+  // Create a stream to collect metadata (FileLinks)
+  const { readable, writable } = new TransformStream()
+
+  // Set up the main UnixFS writer (data goes nowhere here)
+  const unixfsWriter = createWriter({
+    writable: new WritableStream(), // Discard actual DAG output
+    settings: defaultSettings,
+  })
+
+  // Set up the file writer with link metadata writer
+  const unixFsFileLinkWriter = writable.getWriter()
+
+  const fileWriter = createFileWriter({
+    ...unixfsWriter,
+    initOptions: {
+      unixFsFileLinkWriter,
+    },
+  })
+
+  // Start concurrent reading of the metadata stream
+  const fileLinkReader = readable.getReader()
+  const readLinks = (async () => {
+    while (true) {
+      const { done, value } = await fileLinkReader.read()
+      if (done) break
+      fileLinks.push(value)
+    }
+  })()
+
+  // Pipe the blob to the file writer
+  await blob.stream().pipeTo(
+    new WritableStream({
+      async write(chunk) {
+        await fileWriter.write(chunk)
+      },
+    })
+  )
+
+  // Finalize everything
+  await fileWriter.close()
+  await unixfsWriter.close()
+  await unixFsFileLinkWriter.close()
+
+  // Wait for all links to be read
+  await readLinks
+
+  return fileLinks
+}
+
+// Usage
+const blob = new Blob(['Hello UnixFS links'])
+const links = await collectUnixFsFileLinks(blob)
+console.log(links)
+```
+
 ## License
 
 Licensed under either of
@@ -144,4 +226,4 @@ Unless you explicitly state otherwise, any contribution intentionally submitted
 [readablestream]: https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream
 [car]: https://ipld.io/specs/transport/car/carv1/
 [`transformstream`]: https://developer.mozilla.org/en-US/docs/Web/API/TransformStream
-[`writablestream`]: https://developer.mozilla.org/en-US/docs/Web/API/WritableStream
+[`writablestream`]: https://developer.mozilla.org/en-US/docs/Web/API/WritableStream
\ No newline at end of file
diff --git a/src/api.ts b/src/api.ts
index fec8a76..8f9b4b0 100644
--- a/src/api.ts
+++ b/src/api.ts
@@ -23,7 +23,7 @@ import type {
   Options as DirectoryWriterOptions,
   State as DirectoryWriterState,
 } from "./directory.js"
-import { Metadata } from "./unixfs.js"
+import { Metadata, FileLink } from "./unixfs.js"
 
 export type {
   WriterOptions,
@@ -47,6 +47,7 @@ export type {
   MultihashHasher,
   MultihashDigest,
   Metadata,
+  FileLink,
 }
 
 /**
diff --git a/src/file.js b/src/file.js
index 2d72632..5fa4e4b 100644
--- a/src/file.js
+++ b/src/file.js
@@ -28,7 +28,7 @@ export const defaults = () => ({
  * @param {Partial<API.EncoderSettings<Layout>>} config
  * @returns {API.EncoderSettings<Layout>}
  */
-export const configure = config => ({
+export const configure = (config) => ({
   ...defaults(),
   ...config,
 })
@@ -50,8 +50,15 @@ export const UnixFSRawLeaf = {
  * @param {API.Options<Layout>} options
  * @returns {API.View<Layout>}
  */
-export const create = ({ writer, metadata = {}, settings = defaults() }) =>
-  new FileWriterView(Writer.init(writer, metadata, configure(settings)))
+export const create = ({
+  writer,
+  metadata = {},
+  settings = defaults(),
+  initOptions = {},
+}) =>
+  new FileWriterView(
+    Writer.init(writer, metadata, configure(settings), initOptions)
+  )
 
 /**
  * @template T
@@ -98,7 +105,7 @@ export const close = async (
  */
 const perform = (view, effect) =>
   Task.fork(
-    Task.loop(effect, message => {
+    Task.loop(effect, (message) => {
       const { state, effect } = Writer.update(message, view.state)
       view.state = state
       return effect
diff --git a/src/file/api.ts b/src/file/api.ts
index 1b3d78b..b86eeb4 100644
--- a/src/file/api.ts
+++ b/src/file/api.ts
@@ -72,10 +72,17 @@ export interface EncoderSettings<Layout extends unknown = unknown> {
   linker: Linker
 }
 
+export interface InitOptions {
+  unixFsFileLinkWriter?: UnixFsFileLinkWriter
+}
+
+export interface UnixFsFileLinkWriter extends StreamWriter<UnixFS.FileLink> {}
+
 export interface Options<Layout = unknown> {
   writer: BlockWriter
   metadata?: UnixFS.Metadata
   settings?: EncoderSettings<Layout>
+  initOptions?: InitOptions
 }
 
 export interface CloseOptions {
diff --git a/src/file/writer.js b/src/file/writer.js
index 1f3c225..4cf2ec7 100644
--- a/src/file/writer.js
+++ b/src/file/writer.js
@@ -13,6 +13,7 @@ import * as Queue from "./layout/queue.js"
  * readonly metadata: UnixFS.Metadata
  * readonly config: API.EncoderSettings<Layout>
  * readonly writer: API.BlockWriter
+ * readonly unixFsFileLinkWriter?: API.UnixFsFileLinkWriter
  * chunker: Chunker.Chunker
  * layout: Layout
  * nodeQueue: Queue.Queue
@@ -25,6 +26,7 @@ import * as Queue from "./layout/queue.js"
  * readonly metadata: UnixFS.Metadata
  * readonly config: API.EncoderSettings<Layout>
  * readonly writer: API.BlockWriter
+ * readonly unixFsFileLinkWriter?: API.UnixFsFileLinkWriter
  * readonly rootID: Layout.NodeID
  * readonly end?: Task.Fork<void, never>
  * chunker?: null
@@ -39,6 +41,7 @@ import * as Queue from "./layout/queue.js"
  * readonly metadata: UnixFS.Metadata
  * readonly config: API.EncoderSettings<Layout>
  * readonly writer: API.BlockWriter
+ * readonly unixFsFileLinkWriter?: API.UnixFsFileLinkWriter
  * readonly link: Layout.Link
  * chunker?: null
  * layout?: null
@@ -63,6 +66,7 @@ import * as Queue from "./layout/queue.js"
  * |{type:"write", bytes:Uint8Array}
  * |{type:"link", link:API.EncodedFile}
  * |{type:"block"}
+ * |{type:"fileLink"}
  * |{type: "close"}
  * |{type: "end"}
  * } Message
@@ -82,6 +86,9 @@ export const update = (message, state) => {
     /* c8 ignore next 2 */
     case "block":
       return { state, effect: Task.none() }
+    /* c8 ignore next 2 */
+    case "fileLink":
+      return { state, effect: Task.none() }
     case "close":
       return close(state)
     case "end":
@@ -96,9 +103,10 @@ export const update = (message, state) => {
  * @param {API.BlockWriter} writer
  * @param {UnixFS.Metadata} metadata
  * @param {API.EncoderSettings} config
+ * @param {API.InitOptions} [options]
  * @returns {State<Layout>}
  */
-export const init = (writer, metadata, config) => {
+export const init = (writer, metadata, config, options = {}) => {
   return {
     status: "open",
     metadata,
@@ -116,6 +124,7 @@ export const init = (writer, metadata, config) => {
     // overhead.
     // @see https://github.com/Gozala/vectrie
     nodeQueue: Queue.mutable(),
+    unixFsFileLinkWriter: options.unixFsFileLinkWriter,
   }
 }
 /**
@@ -188,11 +197,23 @@ export const link = (state, { id, link, block }) => {
       ? state.end.resume()
       : Task.none()
 
+  if (!state.unixFsFileLinkWriter) {
+    return {
+      state: newState,
+      effect: Task.listen({
+        link: Task.effects(tasks),
+        block: writeBlock(state.writer, block),
+        end,
+      }),
+    }
+  }
+
   return {
     state: newState,
     effect: Task.listen({
       link: Task.effects(tasks),
       block: writeBlock(state.writer, block),
+      fileLink: writeFileLink(state.unixFsFileLinkWriter, link),
       end,
     }),
   }
@@ -203,7 +224,7 @@ export const link = (state, { id, link, block }) => {
  * @param {State<Layout>} state
  * @returns {Update<Layout>}
  */
-export const close = state => {
+export const close = (state) => {
   if (state.status === "open") {
     const { chunks } = Chunker.close(state.chunker)
     const { layout, ...write } = state.config.fileLayout.write(
@@ -269,7 +290,7 @@ export const close = state => {
  * @param {API.EncoderSettings} config
  */
 const encodeLeaves = (leaves, config) =>
-  leaves.map(leaf => encodeLeaf(config, leaf, config.fileChunkEncoder))
+  leaves.map((leaf) => encodeLeaf(config, leaf, config.fileChunkEncoder))
 
 /**
  * @param {API.EncoderSettings} config
@@ -286,6 +307,7 @@ const encodeLeaf = function* ({ hasher, linker }, { id, content }, encoder) {
   const link = /** @type {UnixFS.FileLink} */ ({
     cid,
     contentByteLength: content ? content.byteLength : 0,
+    contentByteOffset: content ? content.byteOffset : 0,
     dagByteLength: bytes.byteLength,
   })
 
@@ -297,7 +319,7 @@ const encodeLeaf = function* ({ hasher, linker }, { id, content }, encoder) {
  * @param {API.EncoderSettings} config
  */
 const encodeBranches = (nodes, config) =>
-  nodes.map(node => encodeBranch(config, node))
+  nodes.map((node) => encodeBranch(config, node))
 
 /**
  * @template Layout
@@ -338,13 +360,30 @@ export const writeBlock = function* (writer, block) {
   writer.write(block)
 }
 
+/**
+ * @param {API.UnixFsFileLinkWriter} writer
+ * @param {Layout.Link} link
+ * @returns {Task.Task<void, never>}
+ */
+
+export const writeFileLink = function* (writer, link) {
+  /* c8 ignore next 3 */
+  if (!writer) {
+    return
+  }
+  if ((writer.desiredSize || 0) <= 0) {
+    yield* Task.wait(writer.ready)
+  }
+  writer.write(link)
+}
+
 /**
  *
  * @param {Uint8Array|Chunker.Chunk} buffer
  * @returns
  */
 
-const asUint8Array = buffer =>
+const asUint8Array = (buffer) =>
   buffer instanceof Uint8Array
     ? buffer
     : buffer.copyTo(new Uint8Array(buffer.byteLength), 0)
@@ -353,4 +392,4 @@ const asUint8Array = buffer =>
  * @param {Layout.Node} node
  * @returns {node is Layout.Leaf}
  */
-const isLeafNode = node => node.children == null
+const isLeafNode = (node) => node.children == null
diff --git a/src/unixfs.ts b/src/unixfs.ts
index a4e88b7..dcc0e15 100644
--- a/src/unixfs.ts
+++ b/src/unixfs.ts
@@ -6,10 +6,15 @@ import type {
   Link as IPLDLink,
   Version as LinkVersion,
   Block as IPLDBlock,
-  BlockView as IPLDBlockView
+  BlockView as IPLDBlockView,
 } from "multiformats"
 import { Data, type IData } from "../gen/unixfs.js"
-export type { MultihashHasher, MultibaseEncoder, MultihashDigest, BlockEncoder }
+export type {
+  MultihashHasher,
+  MultibaseEncoder,
+  MultihashDigest,
+  BlockEncoder,
+}
 export * as Layout from "./file/layout/api"
 
 import NodeType = Data.DataType
@@ -161,6 +166,11 @@ export interface ContentDAGLink<T> extends DAGLink<T> {
    * Total number of bytes in the file
    */
   readonly contentByteLength: number
+
+  /**
+   * Offset bytes in the file
+   */
+  readonly contentByteOffset?: number
 }
 
 /**
diff --git a/test/directory.spec.js b/test/directory.spec.js
index ce466d3..012a6b1 100644
--- a/test/directory.spec.js
+++ b/test/directory.spec.js
@@ -21,7 +21,7 @@ describe("test directory", () => {
     const output = await collect(readable)
 
     assert.deepEqual(
-      output.map($ => $.cid),
+      output.map(($) => $.cid),
       [
         Link.parse(
           "bafybeiczsscdsbs7ffqz55asqdf3smv6klcw3gofszvwlyarci47bgf354"
@@ -47,6 +47,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 45,
       contentByteLength: 37,
+      contentByteOffset: 0,
     })
 
     root.set("file.txt", fileLink)
@@ -65,7 +66,7 @@ describe("test directory", () => {
     const output = await blocks
 
     assert.deepEqual(
-      output.map($ => $.cid),
+      output.map(($) => $.cid),
       [
         Link.parse(
           "bafybeidequ5soq6smzafv4lb76i5dkvl5fzgvrxz4bmlc2k4dkikklv2j4"
@@ -142,6 +143,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -152,6 +154,7 @@ describe("test directory", () => {
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta"
       ),
       dagByteLength: 11,
+      contentByteOffset: 0,
       contentByteLength: 3,
     })
 
@@ -173,7 +176,7 @@ describe("test directory", () => {
     writer.close()
     const items = await blocks
     assert.deepEqual(
-      items.map(item => item.cid.toString()),
+      items.map((item) => item.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -196,6 +199,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -207,6 +211,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 11,
       contentByteLength: 3,
+      contentByteOffset: 0,
     })
 
     root.set("hello", hello)
@@ -223,7 +228,7 @@ describe("test directory", () => {
     writer.close()
     const items = await blocks
     assert.deepEqual(
-      items.map(item => item.cid.toString()),
+      items.map((item) => item.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -246,6 +251,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -263,7 +269,7 @@ describe("test directory", () => {
     writer.close()
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeiczsscdsbs7ffqz55asqdf3smv6klcw3gofszvwlyarci47bgf354",
@@ -300,6 +306,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -311,6 +318,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 11,
       contentByteLength: 3,
+      contentByteOffset: 0,
     })
 
     root.set("hello", hello)
@@ -330,7 +338,7 @@ describe("test directory", () => {
     writer.close()
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -353,6 +361,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -364,6 +373,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 11,
       contentByteLength: 3,
+      contentByteOffset: 0,
     })
 
     root.set("hello", hello)
@@ -388,7 +398,7 @@ describe("test directory", () => {
     writer.close()
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -417,7 +427,7 @@ describe("test directory", () => {
 
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeieuo4clbaujw35wxt7s4jlorbgztvufvdrcxxb6hik5mzfqku2tbq",
@@ -439,6 +449,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -450,6 +461,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 11,
       contentByteLength: 3,
+      contentByteOffset: 0,
     })
 
     root.set("hello", hello)
@@ -478,7 +490,7 @@ describe("test directory", () => {
     writer.close()
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -489,7 +501,7 @@ describe("test directory", () => {
     patchWriter.close()
     const delta = await patchReader
     assert.deepEqual(
-      delta.map(block => block.cid.toString()),
+      delta.map((block) => block.cid.toString()),
       ["bafybeibpefc2sgzngxttfwrawvaiewk4hj5yxdp5kik52jpds5ujg3ij44"]
     )
   })
diff --git a/test/file.spec.js b/test/file.spec.js
index 6140f55..57e9625 100644
--- a/test/file.spec.js
+++ b/test/file.spec.js
@@ -46,6 +46,11 @@ describe("test file", () => {
   })
 
   it("splits into 3 chunks", async function () {
+    const rawFiles = [
+      new Uint8Array(CHUNK_SIZE).fill(1),
+      new Uint8Array(CHUNK_SIZE).fill(2),
+      new Uint8Array(CHUNK_SIZE).fill(3),
+    ]
     const { readable, writable } = new TransformStream(
       {},
       {},
@@ -54,15 +59,37 @@ describe("test file", () => {
       }
     )
     const writer = writable.getWriter()
-    const file = UnixFS.createFileWriter({ writer })
-    file.write(new Uint8Array(CHUNK_SIZE).fill(1))
-    file.write(new Uint8Array(CHUNK_SIZE).fill(2))
-    file.write(new Uint8Array(CHUNK_SIZE).fill(3))
+
+    // Capture links metadata
+    /** @type {import('../src/unixfs.js').FileLink[]} */
+    const fileLinkItems = []
+    const { readable: fileLinkReadable, writable: fileLinkWritable } =
+      new TransformStream()
+    // Start consuming links stream asynchronously
+    void (async () => {
+      const reader = fileLinkReadable.getReader()
+      while (true) {
+        const { done, value } = await reader.read()
+        if (done) break
+        fileLinkItems.push(value)
+      }
+    })()
+
+    const file = UnixFS.createFileWriter({
+      writer,
+      initOptions: {
+        unixFsFileLinkWriter: fileLinkWritable.getWriter(),
+      },
+    })
+    for (const rawFile of rawFiles) {
+      file.write(rawFile)
+    }
     const link = await file.close()
 
+    // Check the root CID
     // TODO: So go-ipfs sets CIDv0 links which casuse a mismatch
     assert.deepEqual(link, {
-      contentByteLength: 786432,
+      contentByteLength: CHUNK_SIZE * 3,
       dagByteLength: 786632,
       /** @type {Link.Link} */
       cid: Link.parse(
@@ -71,16 +98,23 @@ describe("test file", () => {
     })
 
     const blocks = readable.getReader()
+
+    // Check the first block
     const r1 = await blocks.read()
     if (r1.done) {
       assert.fail("expected to get a block")
     }
-
     assert.deepEqual(
       r1.value.cid,
       Link.parse("bafybeihhsdoupgd3fnl3e3367ymsanmikafpllldsdt37jzyoh6nuatowe")
     )
+    const l1 = fileLinkItems.find((l) => l.cid.equals(r1.value.cid))
+    assert.isTrue(l1 !== undefined)
+    assert.equal(l1?.contentByteLength, CHUNK_SIZE)
+    assert.equal(l1?.dagByteLength, CHUNK_SIZE + 14)
+    assert.equal(l1?.contentByteOffset, 0)
 
+    // Check the second block
     const r2 = await blocks.read()
     if (r2.done) {
       assert.fail("expected to get a block")
@@ -89,7 +123,13 @@ describe("test file", () => {
       r2.value.cid,
       Link.parse("bafybeief3dmadxfymhhhrflqytqmlhlz47w6glaxvyzmm6s6tpfb6izzee")
     )
+    const l2 = fileLinkItems.find((l) => l.cid.equals(r2.value.cid))
+    assert.isTrue(l2 !== undefined)
+    assert.equal(l2?.contentByteLength, CHUNK_SIZE)
+    assert.equal(l2?.dagByteLength, CHUNK_SIZE + 14)
+    assert.equal(l2?.contentByteOffset, CHUNK_SIZE)
 
+    // Check the third block
     const r3 = await blocks.read()
     if (r3.done) {
       assert.fail("expected to get a block")
@@ -98,8 +138,19 @@ describe("test file", () => {
       r3.value.cid,
       Link.parse("bafybeihznihf5g5ibdyoawn7uu3inlyqrxjv63lt6lop6h3w6rzwrp67a4")
     )
+    const l3 = fileLinkItems.find((l) => l.cid.equals(r3.value.cid))
+    assert.isTrue(l3 !== undefined)
+    assert.equal(l3?.contentByteLength, CHUNK_SIZE)
+    assert.equal(l3?.dagByteLength, CHUNK_SIZE + 14)
+    assert.equal(l3?.contentByteOffset, CHUNK_SIZE * 2)
 
     await writer.close()
+
+    // Check root
+    assert.isTrue(
+      fileLinkItems.find((l) => l.cid.equals(link.cid)) !== undefined
+    )
+    assert.equal(fileLinkItems.length, 4)
   })
 
   it("--chunker=size-65535 --trickle=false --raw-leaves=false --cid-version=1", async () => {
@@ -130,6 +181,7 @@ describe("test file", () => {
     }
 
     const link = await file.close()
+    console.log("link", link)
     assert.deepEqual(link, {
       /** @type {Link.Link} */
       cid: Link.parse(
@@ -292,6 +344,7 @@ describe("test file", () => {
         "bafybeif7ztnhq65lumvvtr4ekcwd2ifwgm3awq4zfr3srh462rwyinlb4y"
       ),
       contentByteLength: 0,
+      contentByteOffset: 0,
       dagByteLength: 6,
     })
   })
@@ -312,6 +365,7 @@ describe("test file", () => {
         "bafybeidequ5soq6smzafv4lb76i5dkvl5fzgvrxz4bmlc2k4dkikklv2j4"
       ),
       contentByteLength: 37,
+      contentByteOffset: 0,
       dagByteLength: 45,
     })
   })
@@ -335,6 +389,7 @@ describe("test file", () => {
         "bafybeidequ5soq6smzafv4lb76i5dkvl5fzgvrxz4bmlc2k4dkikklv2j4"
       ),
       contentByteLength: 37,
+      contentByteOffset: 0,
       dagByteLength: 45,
     })
   })
diff --git a/test/lib.spec.js b/test/lib.spec.js
index f82a3f3..aafc7fc 100644
--- a/test/lib.spec.js
+++ b/test/lib.spec.js
@@ -15,13 +15,14 @@ describe("UnixFS.createWriter", () => {
         "bafybeihykld7uyxzogax6vgyvag42y7464eywpf55gxi5qpoisibh3c5wa"
       ),
       dagByteLength: 19,
+      contentByteOffset: 0,
       contentByteLength: 11,
     })
     writer.close()
 
     const blocks = await reader
     assert.deepEqual(
-      blocks.map($ => $.cid.toString()),
+      blocks.map(($) => $.cid.toString()),
       ["bafybeihykld7uyxzogax6vgyvag42y7464eywpf55gxi5qpoisibh3c5wa"]
     )
   })
@@ -39,13 +40,14 @@ describe("UnixFS.createWriter", () => {
       ),
       dagByteLength: 19,
       contentByteLength: 11,
+      contentByteOffset: 0,
     })
 
     writer.close()
 
     const blocks = await reader
     assert.deepEqual(
-      blocks.map($ => $.cid.toString()),
+      blocks.map(($) => $.cid.toString()),
       ["bafybeihykld7uyxzogax6vgyvag42y7464eywpf55gxi5qpoisibh3c5wa"]
     )
   })
@@ -69,7 +71,7 @@ describe("UnixFS.createWriter", () => {
     const blocks = await reader
 
     assert.deepEqual(
-      blocks.map($ => $.cid.toString()),
+      blocks.map(($) => $.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeieuo4clbaujw35wxt7s4jlorbgztvufvdrcxxb6hik5mzfqku2tbq",
@@ -96,7 +98,7 @@ describe("UnixFS.createWriter", () => {
     const blocks = await reader
 
     assert.deepEqual(
-      blocks.map($ => $.cid.toString()),
+      blocks.map(($) => $.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeieuo4clbaujw35wxt7s4jlorbgztvufvdrcxxb6hik5mzfqku2tbq",
@@ -129,7 +131,7 @@ describe("UnixFS.createWriter", () => {
     const blocks = await reader
 
     assert.deepEqual(
-      blocks.map($ => $.cid.toString()),
+      blocks.map(($) => $.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeieuo4clbaujw35wxt7s4jlorbgztvufvdrcxxb6hik5mzfqku2tbq",
@@ -154,6 +156,7 @@ describe("UnixFS.withCapacity", async () => {
     ),
     dagByteLength: 19,
     contentByteLength: 11,
+    contentByteOffset: 0,
   })
 
   assert.equal(fs.writer.desiredSize, 128 - 19)
@@ -168,6 +171,7 @@ describe("UnixFS.withCapacity", async () => {
     ),
     dagByteLength: 11,
     contentByteLength: 3,
+    contentByteOffset: 0,
   })
 
   assert.equal(fs.writer.desiredSize, 128 - 19 - 11)
diff --git a/test/sharded-directory.spec.js b/test/sharded-directory.spec.js
index e5a5bad..e3c9cd3 100644
--- a/test/sharded-directory.spec.js
+++ b/test/sharded-directory.spec.js
@@ -21,7 +21,7 @@ describe("test directory", () => {
     const output = await collect(readable)
 
     assert.deepEqual(
-      output.map($ => $.cid),
+      output.map(($) => $.cid),
       [
         Link.parse(
           "bafybeifoplefg5piy3pjhlp73q7unqx4hwecxeu7opfqfmg352pkpljt6m"
@@ -47,6 +47,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 45,
       contentByteLength: 37,
+      contentByteOffset: 0,
     })
 
     root.set("file.txt", fileLink)
@@ -65,7 +66,7 @@ describe("test directory", () => {
     const output = await blocks
 
     assert.deepEqual(
-      output.map($ => $.cid),
+      output.map(($) => $.cid),
       [
         Link.parse(
           "bafybeidequ5soq6smzafv4lb76i5dkvl5fzgvrxz4bmlc2k4dkikklv2j4"
@@ -94,6 +95,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 45,
       contentByteLength: 37,
+      contentByteOffset: 0,
     })
 
     for (let i = 0; i < 100; i++) {
@@ -115,28 +117,68 @@ describe("test directory", () => {
     const output = await blocks
 
     assert.deepEqual(
-      output.map($ => $.cid),
+      output.map(($) => $.cid),
       [
-        Link.parse("bafybeidequ5soq6smzafv4lb76i5dkvl5fzgvrxz4bmlc2k4dkikklv2j4"),
-        Link.parse("bafybeic66itcox6c3pozwsktz552f3pd3eanqr74jpvjezchwrkpqemjru"),
-        Link.parse("bafybeigyad752jkaj6qrlgtvovw5dzvhcj7pfvo5pjxkdlzec3kn3qqcoy"),
-        Link.parse("bafybeiflrsirdjonnavtsdg7vb63z7mcnzuymuv6eiwxw2wxqkezhludjm"),
-        Link.parse("bafybeigw2ilsvwhg3uglrmryyuk7dtu4yudr5naerrzb5e7ibmk7rscu3y"),
-        Link.parse("bafybeicprkb6dv56v3ezgj4yffbsueamhkkodfsxvwyaty3okfu6tgq3rm"),
-        Link.parse("bafybeienx5re7fb3s2crypbkkyp5l5zo5xb5bqfxh67ieq2aivgtaw5bqq"),
-        Link.parse("bafybeiewng4vb4elq23cjybjhehg2z3lshskzstxzgrhllyb7jsz2dckdq"),
-        Link.parse("bafybeifz4lbafvzkj7njb3cdr7r3ngl5643jhtghl2ntbvoyx5hocvepvy"),
-        Link.parse("bafybeibperpo4gxoi7x3g7entslorxizzy3imr44hujjqrus4hfs4ekqge"),
-        Link.parse("bafybeiamtplq4n5kdlhorxmougus3y54r52frrvotkduzy7kfgyrepvylu"),
-        Link.parse("bafybeieqvwd6ditluxwzrbvq3ffusuykxbljlqyf7gbf7esi6ake4xh27a"),
-        Link.parse("bafybeigkk3fanqwihj5qautj4yzluxnh3okblouotd2qkreijejdic2fui"),
-        Link.parse("bafybeiafn56xmx6hqgs4ig4yc24cdnbzyghjml6yhg3hmmemkrwl4irluu"),
-        Link.parse("bafybeieu5uzq5jbtuhnaazl36pjygv57virwr3tbdgqujhpya5w7dfosz4"),
-        Link.parse("bafybeid57gn3655jtgnnocwnjznifyltepqoiu3chbawyy2f263hm3qylm"),
-        Link.parse("bafybeig3iwqy4v44nvgyabirtbel6sbk6pzfuwdpzj4z26vczda2nycyrq"),
-        Link.parse("bafybeigrpoorhusehwpw2caoe7mw65xaundu227vcxqv6mqfeo65tcwxqm"),
-        Link.parse("bafybeif3iq6dnq2qixkoqnmyvijplu6x5depgmfgpfncpxkcx5ytajrxxy"),
-        Link.parse("bafybeidzpkzefoys5ani6qfvrpxyjiolmy6ng445uceov2a33r5bw43qwe"),
+        Link.parse(
+          "bafybeidequ5soq6smzafv4lb76i5dkvl5fzgvrxz4bmlc2k4dkikklv2j4"
+        ),
+        Link.parse(
+          "bafybeic66itcox6c3pozwsktz552f3pd3eanqr74jpvjezchwrkpqemjru"
+        ),
+        Link.parse(
+          "bafybeigyad752jkaj6qrlgtvovw5dzvhcj7pfvo5pjxkdlzec3kn3qqcoy"
+        ),
+        Link.parse(
+          "bafybeiflrsirdjonnavtsdg7vb63z7mcnzuymuv6eiwxw2wxqkezhludjm"
+        ),
+        Link.parse(
+          "bafybeigw2ilsvwhg3uglrmryyuk7dtu4yudr5naerrzb5e7ibmk7rscu3y"
+        ),
+        Link.parse(
+          "bafybeicprkb6dv56v3ezgj4yffbsueamhkkodfsxvwyaty3okfu6tgq3rm"
+        ),
+        Link.parse(
+          "bafybeienx5re7fb3s2crypbkkyp5l5zo5xb5bqfxh67ieq2aivgtaw5bqq"
+        ),
+        Link.parse(
+          "bafybeiewng4vb4elq23cjybjhehg2z3lshskzstxzgrhllyb7jsz2dckdq"
+        ),
+        Link.parse(
+          "bafybeifz4lbafvzkj7njb3cdr7r3ngl5643jhtghl2ntbvoyx5hocvepvy"
+        ),
+        Link.parse(
+          "bafybeibperpo4gxoi7x3g7entslorxizzy3imr44hujjqrus4hfs4ekqge"
+        ),
+        Link.parse(
+          "bafybeiamtplq4n5kdlhorxmougus3y54r52frrvotkduzy7kfgyrepvylu"
+        ),
+        Link.parse(
+          "bafybeieqvwd6ditluxwzrbvq3ffusuykxbljlqyf7gbf7esi6ake4xh27a"
+        ),
+        Link.parse(
+          "bafybeigkk3fanqwihj5qautj4yzluxnh3okblouotd2qkreijejdic2fui"
+        ),
+        Link.parse(
+          "bafybeiafn56xmx6hqgs4ig4yc24cdnbzyghjml6yhg3hmmemkrwl4irluu"
+        ),
+        Link.parse(
+          "bafybeieu5uzq5jbtuhnaazl36pjygv57virwr3tbdgqujhpya5w7dfosz4"
+        ),
+        Link.parse(
+          "bafybeid57gn3655jtgnnocwnjznifyltepqoiu3chbawyy2f263hm3qylm"
+        ),
+        Link.parse(
+          "bafybeig3iwqy4v44nvgyabirtbel6sbk6pzfuwdpzj4z26vczda2nycyrq"
+        ),
+        Link.parse(
+          "bafybeigrpoorhusehwpw2caoe7mw65xaundu227vcxqv6mqfeo65tcwxqm"
+        ),
+        Link.parse(
+          "bafybeif3iq6dnq2qixkoqnmyvijplu6x5depgmfgpfncpxkcx5ytajrxxy"
+        ),
+        Link.parse(
+          "bafybeidzpkzefoys5ani6qfvrpxyjiolmy6ng445uceov2a33r5bw43qwe"
+        ),
       ]
     )
   })
@@ -206,6 +248,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -217,6 +260,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 11,
       contentByteLength: 3,
+      contentByteOffset: 0,
     })
 
     root.set("hello", hello)
@@ -237,7 +281,7 @@ describe("test directory", () => {
     writer.close()
     const items = await blocks
     assert.deepEqual(
-      items.map(item => item.cid.toString()),
+      items.map((item) => item.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -260,6 +304,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -271,6 +316,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 11,
       contentByteLength: 3,
+      contentByteOffset: 0,
     })
 
     root.set("hello", hello)
@@ -287,7 +333,7 @@ describe("test directory", () => {
     writer.close()
     const items = await blocks
     assert.deepEqual(
-      items.map(item => item.cid.toString()),
+      items.map((item) => item.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -310,6 +356,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -327,7 +374,7 @@ describe("test directory", () => {
     writer.close()
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeifoplefg5piy3pjhlp73q7unqx4hwecxeu7opfqfmg352pkpljt6m",
@@ -364,6 +411,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -375,6 +423,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 11,
       contentByteLength: 3,
+      contentByteOffset: 0,
     })
 
     root.set("hello", hello)
@@ -394,7 +443,7 @@ describe("test directory", () => {
     writer.close()
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -406,7 +455,10 @@ describe("test directory", () => {
       await root.close()
       assert.fail()
     } catch (/** @type {any} */ err) {
-      assert.equal(err.message, "Can not change written HAMT directory, but you can .fork() and make changes to it")
+      assert.equal(
+        err.message,
+        "Can not change written HAMT directory, but you can .fork() and make changes to it"
+      )
     }
   })
 
@@ -424,6 +476,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -435,6 +488,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 11,
       contentByteLength: 3,
+      contentByteOffset: 0,
     })
 
     root.set("hello", hello)
@@ -459,7 +513,7 @@ describe("test directory", () => {
     writer.close()
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -488,7 +542,7 @@ describe("test directory", () => {
 
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeihccqhztoqxfi5mmnv55iofsz7slpzq4gnktf3vzycavqbms5eote",
@@ -510,6 +564,7 @@ describe("test directory", () => {
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq"
       ),
       contentByteLength: 5,
+      contentByteOffset: 0,
       dagByteLength: 13,
     })
 
@@ -521,6 +576,7 @@ describe("test directory", () => {
       ),
       dagByteLength: 11,
       contentByteLength: 3,
+      contentByteOffset: 0,
     })
 
     root.set("hello", hello)
@@ -549,7 +605,7 @@ describe("test directory", () => {
     writer.close()
     const blocks = await reader
     assert.deepEqual(
-      blocks.map(block => block.cid.toString()),
+      blocks.map((block) => block.cid.toString()),
       [
         "bafybeid3weurg3gvyoi7nisadzolomlvoxoppe2sesktnpvdve3256n5tq",
         "bafybeigl43jff4muiw2m6kzqhm7xpz6ti7etiujklpnc6vpblzjvvwqmta",
@@ -560,7 +616,7 @@ describe("test directory", () => {
     patchWriter.close()
     const delta = await patchReader
     assert.deepEqual(
-      delta.map(block => block.cid.toString()),
+      delta.map((block) => block.cid.toString()),
       ["bafybeihxagpxz7lekn7exw6ob526d6pgvnzc3kgtpkbh7ze73e2oc7oxpa"]
     )
   })
@@ -714,7 +770,7 @@ describe("test directory", () => {
     }
     root.set("file.txt", fileLink)
     assert.equal(root.size, 1)
-    root.state.entries.forEach(entry => assert.deepEqual(entry, fileLink))
+    root.state.entries.forEach((entry) => assert.deepEqual(entry, fileLink))
   })
 
   it("writer state .get", async function () {