diff --git a/src/clean.ts b/src/clean.ts
index f3acde4..7b78c13 100644
--- a/src/clean.ts
+++ b/src/clean.ts
@@ -1,34 +1,28 @@
-import { Context } from "@code-engine/types";
 import { ono } from "ono";
-import { resolve } from "path";
 import * as trash from "trash";
-import { NormalizedConfig } from "./normalize-config";
+import { FSPromises } from "./normalize-config";
 
 /**
  * Cleans the destination directory by deleting all of its contents.
  */
-export function clean(config: NormalizedConfig) {
-  return async (context: Context): Promise<void> => {
-    // Resolve the output path, relative to the config path and/or the CWD
-    let dir = resolve(context.cwd, config.path);
-    let exists = await directoryExists(dir, config);
+export async function clean(dir: string, fs: FSPromises) {
+  let exists = await directoryExists(dir, fs);
 
-    if (exists) {
-      // Move the output directory to the OS trash.
-      // This is safer than permanently deleting it,
-      // and allows users to roll-back to previous output if they want.
-      await trash(dir, { glob: false });
-    }
-  };
+  if (exists) {
+    // Move the output directory to the OS trash.
+    // This is safer than permanently deleting it,
+    // and allows users to roll-back to previous output if they want.
+    await trash(dir, { glob: false });
+  }
 }
 
 /**
  * Determines whether the specified directory exists.
  * An error is thrown if the path exists and is not a directory.
  */
-async function directoryExists(dir: string, config: NormalizedConfig): Promise<boolean> {
+async function directoryExists(dir: string, fs: FSPromises): Promise<boolean> {
   try {
-    let stats = await config.fs.promises.stat(dir);
+    let stats = await fs.promises.stat(dir);
 
     if (stats.isDirectory()) {
       // The directory exists
diff --git a/src/index.ts b/src/index.ts
index 429d6e0..b4f0728 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,22 +1,4 @@
-import { Plugin } from "@code-engine/types";
-import { clean } from "./clean";
-import { FileSystemConfig } from "./config";
-import { normalizeConfig } from "./normalize-config";
-import { processFile } from "./process-file";
-
-/**
- * A CodeEngine plugin that writes files to the filesystem.
- */
-function filesystem(conf?: FileSystemConfig): Plugin {
-  let config = normalizeConfig(conf);
-
-  return {
-    name: "Filesystem Destination",
-    filter: config.filter,
-    processFile: processFile(config),
-    clean: clean(config),
-  };
-}
+import { filesystem } from "./plugin";
 
 // Named exports
 export * from "./config";
diff --git a/src/plugin.ts b/src/plugin.ts
new file mode 100644
index 0000000..04d3262
--- /dev/null
+++ b/src/plugin.ts
@@ -0,0 +1,39 @@
+import { File, Plugin, Run } from "@code-engine/types";
+import { resolve } from "path";
+import { clean } from "./clean";
+import { FileSystemConfig } from "./config";
+import { normalizeConfig } from "./normalize-config";
+import { writeFile } from "./write-file";
+
+/**
+ * A CodeEngine plugin that writes files to the filesystem.
+ */
+export function filesystem(conf?: FileSystemConfig): Plugin {
+  let config = normalizeConfig(conf);
+  let dir: string;
+
+  return {
+    name: "Filesystem Destination",
+
+    filter: config.filter,
+
+    initialize() {
+      // Resolve the output directory, relative to the CodeEngine CWD
+      dir = resolve(this.engine.cwd, config.path);
+    },
+
+    /**
+     * Writes a file to the filesystem, creating parent directories if needed.
+     */
+    async processFile(file: File, run: Run) {
+      await writeFile(dir, file, config.fs);
+    },
+
+    /**
+     * Cleans the destination directory by deleting all of its contents.
+     */
+    async clean() {
+      await clean(dir, config.fs);
+    },
+  };
+}
diff --git a/src/process-file.ts b/src/write-file.ts
similarity index 51%
rename from src/process-file.ts
rename to src/write-file.ts
index e58052d..194c3a2 100644
--- a/src/process-file.ts
+++ b/src/write-file.ts
@@ -1,43 +1,32 @@
-import { Context, File, FileProcessor } from "@code-engine/types";
+import { File } from "@code-engine/types";
 import { dirname, resolve } from "path";
-import { FSPromises, NormalizedConfig } from "./normalize-config";
+import { FSPromises } from "./normalize-config";
 
 /**
- * Writes a file to the filesystem.
+ * Writes the given contents to the specified file path, creating the parent directories if needed.
  *
  * This method is called in parallel by CodeEngine based on the `concurrency` setting.
  * All filesystem IO in Node.js is done via the LibUV thread pool, which defaults to 4 threads.
  * This means that the number of concurrent file writes is the MINIMUM of CodeEngine's `concurrency`
  * setting and LibUV's thread pool size.
  */
-export function processFile(config: NormalizedConfig): FileProcessor {
-  return async (file: File, context: Context): Promise<File> => {
-    // Resolve the output path, relative to the config path and/or the CWD
-    let path = resolve(context.cwd, config.path, file.path);
-
-    await writeFile(path, file.contents, config.fs);
-    return file;
-  };
-}
+export async function writeFile(baseDir: string, file: File, fs: FSPromises, retry = true): Promise<void> {
+  let absolutePath = resolve(baseDir, file.path);
 
-/**
- * Writes the given contents to the specified file path, creating the parent directories if needed.
- */
-async function writeFile(path: string, contents: Buffer, fs: FSPromises, retry = true): Promise<void> {
   try {
     // Try to write the file
-    await fs.promises.writeFile(path, contents, { flag: "w" });
+    await fs.promises.writeFile(absolutePath, file.contents, { flag: "w" });
   }
   catch (e) {
     let error = e as NodeJS.ErrnoException;
 
     if (error && retry && error.code === "ENOENT") {
       // The directory path doesn't exist, so create it
-      let dir = dirname(path);
+      let dir = dirname(absolutePath);
       await fs.promises.mkdir(dir, { recursive: true });
 
       // Now try again to write the file
-      await writeFile(path, contents, fs, false);
+      await fs.promises.writeFile(absolutePath, file.contents, { flag: "w" });
     }
     else {
       throw error;