diff --git a/.changeset/silent-gifts-repair.md b/.changeset/silent-gifts-repair.md
new file mode 100644
index 0000000..47229ad
--- /dev/null
+++ b/.changeset/silent-gifts-repair.md
@@ -0,0 +1,5 @@
+---
+"@effect/build-utils": patch
+---
+
+add pack v4
diff --git a/src/PackV4.ts b/src/PackV4.ts
new file mode 100644
index 0000000..d57065b
--- /dev/null
+++ b/src/PackV4.ts
@@ -0,0 +1,226 @@
+import * as NodeFileSystem from "@effect/platform-node/NodeFileSystem"
+import * as NodePath from "@effect/platform-node/NodePath"
+import { FileSystem } from "@effect/platform/FileSystem"
+import { Path } from "@effect/platform/Path"
+import * as Effect from "effect/Effect"
+import * as Layer from "effect/Layer"
+import * as Record from "effect/Record"
+import { FsUtils, FsUtilsLive } from "./FsUtils"
+import type { PackageJson } from "./PackageContext"
+import { PackageContext, PackageContextLive } from "./PackageContext"
+
+export const run = Effect.gen(function*() {
+  const fsUtils = yield* FsUtils
+  const fs = yield* FileSystem
+  const path = yield* Path
+  const ctx = yield* PackageContext
+
+  const templates = yield* fsUtils.glob("src/**/.index.ts")
+  const entrypoints: Record<string, string> = {}
+  yield* Effect.forEach(
+    templates,
+    Effect.fnUntraced(function*(template) {
+      const directory = path.dirname(template)
+      const files = (yield* fs.readDirectory(directory)).map((_) =>
+        path.basename(_)
+      )
+        .filter((path) => path.endsWith(".ts") && !path.startsWith(".")).sort((
+          a,
+          b
+        ) => a.localeCompare(b)).map((file) =>
+          path.relative(
+            "src",
+            path.join(directory, file)
+          ).replace(/\.ts$/, "")
+        )
+
+      for (const file of files) {
+        const isIndex = file.endsWith("index")
+        const stripped = isIndex ? file.slice(0, -6) : file
+        const withDot = stripped === "" ? "." : `./${stripped}`
+        entrypoints[withDot] = file
+      }
+    }),
+    { concurrency: "inherit", discard: true }
+  )
+
+  const buildPackageJson = Effect.sync(() => {
+    const out: Record<string, any> = {
+      name: ctx.packageJson.name,
+      version: ctx.packageJson.version,
+      description: ctx.packageJson.description,
+      license: ctx.packageJson.license,
+      repository: ctx.packageJson.repository,
+      sideEffects: [
+        ...(ctx.hasCjs ? ["/dist/cjs/"] : []),
+        ...(ctx.hasEsm ? ["/dist/esm/"] : [])
+      ].flatMap((dir) =>
+        ctx.packageJson.sideEffects.map((_) =>
+          _.replace(".ts", ".js").replace(".tsx", ".js").replace("/src/", dir)
+        )
+      )
+    }
+
+    const addOptional = (key: keyof PackageJson) => {
+      if (ctx.packageJson[key]) {
+        out[key as string] = ctx.packageJson[key]
+      }
+    }
+
+    addOptional("author")
+    addOptional("homepage")
+    addOptional("dependencies")
+    addOptional("peerDependencies")
+    addOptional("peerDependenciesMeta")
+    addOptional("optionalDependencies")
+    addOptional("gitHead")
+    addOptional("bin")
+
+    if (ctx.packageJson.publishConfig?.provenance === true) {
+      out.publishConfig = { provenance: true }
+    }
+
+    if (
+      ctx.packageJson.publishConfig?.executableFiles !== undefined
+      && ctx.packageJson.publishConfig.executableFiles.length > 0
+    ) {
+      out.publishConfig = {
+        ...out.publishConfig,
+        executableFiles: ctx.packageJson.publishConfig.executableFiles
+      }
+    }
+
+    if (Object.keys(entrypoints).length > 0) {
+      const main = "." in entrypoints ? entrypoints["."] : undefined
+      if (main !== undefined) {
+        out.main = `./dist/${ctx.hasCjs ? "cjs" : "esm"}/${main}.js`
+
+        if (ctx.hasEsm && ctx.hasCjs) {
+          out.module = `./dist/esm/${main}.js`
+        }
+
+        if (ctx.hasDts) {
+          out.types = `./dist/dts/${main}.d.ts`
+        }
+      }
+
+      out.exports = Record.fromEntries(
+        Object.entries(entrypoints).map(([entry, module]) => {
+          return [entry, {
+            types: `./dist/dts/${module}.d.ts`,
+            import: `./dist/esm/${module}.js`,
+            default: `./dist/cjs/${module}.js`
+          }]
+        })
+      )
+
+      out.typesVersions = {
+        "*": Record.fromEntries(
+          Object.entries(entrypoints)
+            .filter(([entry]) => entry !== ".")
+            .map(([entry, module]) => [entry.replace(/^\.\//, ""), [
+              `./dist/dts/${module}.d.ts`
+            ]])
+        )
+      }
+    }
+
+    return out
+  })
+
+  const createProxies = Effect.forEach(
+    Object.entries(entrypoints).filter(([entry]) => entry !== "."),
+    ([entry, module]) =>
+      Effect.gen(function*() {
+        yield* fsUtils.mkdirCached(`dist/${entry}`)
+
+        const out: Record<string, any> = {
+          sideEffects: []
+        }
+
+        out.main = path.relative(
+          `dist/${entry}`,
+          `dist/dist/${ctx.hasCjs ? "cjs" : "esm"}/${module}.js`
+        )
+
+        if (ctx.hasEsm && ctx.hasCjs) {
+          out.module = path.relative(
+            `dist/${entry}`,
+            `dist/dist/esm/${module}.js`
+          )
+        }
+
+        out.types = path.relative(
+          `dist/${entry}`,
+          `dist/dist/dts/${module}.d.ts`
+        )
+
+        yield* fsUtils.writeJson(`dist/${entry}/package.json`, out)
+      }),
+    {
+      concurrency: "inherit",
+      discard: true
+    }
+  )
+
+  const writePackageJson = buildPackageJson.pipe(
+    Effect.map((_) => JSON.stringify(_, null, 2)),
+    Effect.flatMap((_) => fs.writeFileString("dist/package.json", _)),
+    Effect.withSpan("Pack-v4/buildPackageJson")
+  )
+
+  const mkDist = fsUtils.rmAndMkdir("dist")
+  const copyReadme = fs.copy("README.md", "dist/README.md")
+  const copyLicense = fs.copy("LICENSE", "dist/LICENSE")
+
+  const copyEsm = ctx.hasEsm
+    ? fsUtils.rmAndCopy("build/esm", "dist/dist/esm").pipe(
+      Effect.zipRight(fsUtils.writeJson("dist/dist/esm/package.json", {
+        type: "module",
+        sideEffects: ctx.packageJson.sideEffects.map((_) =>
+          _.replace(".ts", ".js").replace("/src/", "/")
+        )
+      }))
+    )
+    : Effect.void
+  const copyCjs = ctx.hasCjs
+    ? fsUtils.rmAndCopy("build/cjs", "dist/dist/cjs")
+    : Effect.void
+  const copyDts = ctx.hasDts
+    ? fsUtils.rmAndCopy("build/dts", "dist/dist/dts")
+    : Effect.void
+  const copySrc = ctx.hasSrc
+    ? fsUtils.rmAndCopy("src", "dist/src").pipe(
+      Effect.zipRight(fs.remove("dist/src/.index.ts").pipe(Effect.ignore))
+    )
+    : Effect.void
+
+  const copySources = Effect.all([
+    copyEsm,
+    copyCjs,
+    copyDts,
+    copySrc
+  ], { concurrency: "inherit", discard: true }).pipe(
+    Effect.withSpan("Pack-v4/copySources")
+  )
+
+  yield* mkDist
+  yield* Effect.all([
+    writePackageJson,
+    copyReadme,
+    copyLicense,
+    copySources,
+    createProxies
+  ], { concurrency: "inherit", discard: true }).pipe(
+    Effect.withConcurrency(10)
+  )
+}).pipe(
+  Effect.provide(
+    Layer.mergeAll(
+      NodeFileSystem.layer,
+      NodePath.layerPosix,
+      FsUtilsLive,
+      PackageContextLive
+    )
+  )
+)
diff --git a/src/main.ts b/src/main.ts
index bb3f0a8..fdc737d 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -7,6 +7,7 @@ import * as Effect from "effect/Effect"
 import * as PackV1 from "./PackV1"
 import * as PackV2 from "./PackV2"
 import * as PackV3 from "./PackV3"
+import * as PackV4 from "./PackV4"
 import * as PrepareV1 from "./PrepareV1"
 import * as PrepareV2 from "./PrepareV2"
 import * as PrepareV3 from "./PrepareV3"
@@ -17,6 +18,7 @@ const run = Command.make("build-utils").pipe(
     Command.make("pack-v1", {}, () => PackV1.run),
     Command.make("pack-v2", {}, () => PackV2.run),
     Command.make("pack-v3", {}, () => PackV3.run),
+    Command.make("pack-v4", {}, () => PackV4.run),
     Command.make("prepare-v1", {}, () => PrepareV1.run),
     Command.make("prepare-v2", {}, () => PrepareV2.run),
     Command.make("prepare-v3", {}, () => PrepareV3.run),