From 740734a3cb5b6b7758d8f9c1558e8651621d66f3 Mon Sep 17 00:00:00 2001
From: Maarten Zuidhoorn <maarten@zuidhoorn.com>
Date: Wed, 7 Jan 2026 11:42:11 +0100
Subject: [PATCH 1/8] Add option for custom manifest to dev server

---
 .../packages/bip32/snap.manifest.dev.json     | 51 +++++++++++++++++++
 packages/snaps-cli/src/builders.ts            |  7 +++
 .../src/commands/manifest/implementation.ts   |  3 +-
 .../snaps-cli/src/commands/sandbox/server.ts  |  2 +-
 .../snaps-cli/src/commands/watch/index.ts     |  4 +-
 .../snaps-cli/src/commands/watch/watch.ts     | 21 ++++++--
 packages/snaps-cli/src/types/yargs.d.ts       |  1 +
 packages/snaps-cli/src/webpack/server.ts      | 40 +++++++++++++--
 packages/snaps-rollup-plugin/src/plugin.ts    | 11 ++--
 packages/snaps-utils/src/manifest/manifest.ts | 10 ++--
 packages/snaps-webpack-plugin/src/plugin.ts   | 37 +++++++-------
 11 files changed, 145 insertions(+), 42 deletions(-)
 create mode 100644 packages/examples/packages/bip32/snap.manifest.dev.json

diff --git a/packages/examples/packages/bip32/snap.manifest.dev.json b/packages/examples/packages/bip32/snap.manifest.dev.json
new file mode 100644
index 0000000000..733d82d22a
--- /dev/null
+++ b/packages/examples/packages/bip32/snap.manifest.dev.json
@@ -0,0 +1,51 @@
+{
+  "version": "2.3.0",
+  "description": "MetaMask example snap demonstrating the use of `snap_getBip32Entropy`.",
+  "proposedName": "BIP-32 Example Snap",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/MetaMask/snaps.git"
+  },
+  "source": {
+    "shasum": "yW/4a7WQ2dCmZHAaX6P2tihFF7azVPkpQ0iJlb/v61A=",
+    "location": {
+      "npm": {
+        "filePath": "dist/bundle.js",
+        "packageName": "@metamask/bip32-example-snap",
+        "registry": "https://registry.npmjs.org"
+      }
+    }
+  },
+  "initialConnections": {
+    "http://localhost:9000": {}
+  },
+  "initialPermissions": {
+    "endowment:rpc": {
+      "dapps": true,
+      "snaps": true
+    },
+    "snap_dialog": {},
+    "snap_getBip32Entropy": [
+      {
+        "path": ["m", "44'", "0'"],
+        "curve": "secp256k1"
+      },
+      {
+        "path": ["m", "44'", "0'"],
+        "curve": "ed25519"
+      },
+      {
+        "path": ["m", "44'", "0'"],
+        "curve": "ed25519Bip32"
+      }
+    ],
+    "snap_getBip32PublicKey": [
+      {
+        "path": ["m", "44'", "0'"],
+        "curve": "secp256k1"
+      }
+    ]
+  },
+  "platformVersion": "10.3.0",
+  "manifestVersion": "0.1"
+}
diff --git a/packages/snaps-cli/src/builders.ts b/packages/snaps-cli/src/builders.ts
index 694610ba8f..8445be40b1 100644
--- a/packages/snaps-cli/src/builders.ts
+++ b/packages/snaps-cli/src/builders.ts
@@ -36,6 +36,13 @@ const builders = {
     normalize: true,
   },
 
+  manifest: {
+    alias: 'm',
+    describe: 'Path to snap.manifest.json file',
+    type: 'string',
+    normalize: true,
+  },
+
   port: {
     alias: 'p',
     describe: 'Local server port for testing',
diff --git a/packages/snaps-cli/src/commands/manifest/implementation.ts b/packages/snaps-cli/src/commands/manifest/implementation.ts
index 573b090b43..608e864390 100644
--- a/packages/snaps-cli/src/commands/manifest/implementation.ts
+++ b/packages/snaps-cli/src/commands/manifest/implementation.ts
@@ -4,7 +4,6 @@ import { writeManifest } from '@metamask/snaps-webpack-plugin';
 import { assert } from '@metamask/utils';
 import { red, yellow, green } from 'chalk';
 import type { Ora } from 'ora';
-import { dirname } from 'path';
 
 import { error, info, warn } from '../../utils';
 
@@ -26,7 +25,7 @@ export async function manifest(
   exports?: string[],
   spinner?: Ora,
 ): Promise<boolean> {
-  const { reports, updated } = await checkManifest(dirname(path), {
+  const { reports, updated } = await checkManifest(path, {
     exports,
     handlerEndowments,
     updateAndWriteManifest: write,
diff --git a/packages/snaps-cli/src/commands/sandbox/server.ts b/packages/snaps-cli/src/commands/sandbox/server.ts
index 0d67fbc2f8..70a6e467a4 100644
--- a/packages/snaps-cli/src/commands/sandbox/server.ts
+++ b/packages/snaps-cli/src/commands/sandbox/server.ts
@@ -11,7 +11,7 @@ import { getServer } from '../../webpack';
  * @returns The server instance.
  */
 export async function startSandbox(config: ProcessedConfig) {
-  const server = getServer(config, [
+  const server = getServer(config, {}, [
     (app) => {
       app.use(
         '/__sandbox__',
diff --git a/packages/snaps-cli/src/commands/watch/index.ts b/packages/snaps-cli/src/commands/watch/index.ts
index 992a7a28e3..eedfcb06dd 100644
--- a/packages/snaps-cli/src/commands/watch/index.ts
+++ b/packages/snaps-cli/src/commands/watch/index.ts
@@ -1,3 +1,4 @@
+import { resolve } from 'path';
 import type yargs from 'yargs';
 
 import { watchHandler } from './watch';
@@ -8,10 +9,11 @@ const command = {
   command: ['watch', 'w'],
   desc: 'Build Snap on change',
   builder: (yarg: yargs.Argv) => {
-    yarg.option('port', builders.port);
+    yarg.option('port', builders.port).option('manifest', builders.manifest);
   },
   handler: async (argv: YargsArgs) =>
     watchHandler(argv.context.config, {
+      manifestPath: argv.manifest && resolve(process.cwd(), argv.manifest),
       port: argv.port,
     }),
 };
diff --git a/packages/snaps-cli/src/commands/watch/watch.ts b/packages/snaps-cli/src/commands/watch/watch.ts
index 2e915c6293..6a3cae7f6d 100644
--- a/packages/snaps-cli/src/commands/watch/watch.ts
+++ b/packages/snaps-cli/src/commands/watch/watch.ts
@@ -8,6 +8,11 @@ import { executeSteps, info } from '../../utils';
 import { getServer } from '../../webpack';
 
 type WatchOptions = {
+  /**
+   * The path to the manifest file.
+   */
+  manifestPath?: string;
+
   /**
    * The port to listen on.
    */
@@ -36,7 +41,7 @@ const steps: Steps<WatchContext> = [
     name: 'Starting the development server.',
     condition: ({ config }) => config.server.enabled,
     task: async ({ config, options, spinner }) => {
-      const server = getServer(config);
+      const server = getServer(config, options);
       const { port } = await server.listen(options.port ?? config.server.port);
 
       info(`The server is listening on http://localhost:${port}.`, spinner);
@@ -44,8 +49,18 @@ const steps: Steps<WatchContext> = [
   },
   {
     name: 'Building the Snap bundle.',
-    task: async ({ config, spinner }) => {
-      await watch(config, { spinner });
+    task: async ({ config, options, spinner }) => {
+      const configWithManifest = options.manifestPath
+        ? {
+            ...config,
+            manifest: {
+              ...config.manifest,
+              path: options.manifestPath,
+            },
+          }
+        : config;
+
+      await watch(configWithManifest, { spinner });
     },
   },
 ];
diff --git a/packages/snaps-cli/src/types/yargs.d.ts b/packages/snaps-cli/src/types/yargs.d.ts
index b3ec09f966..367e581b5b 100644
--- a/packages/snaps-cli/src/types/yargs.d.ts
+++ b/packages/snaps-cli/src/types/yargs.d.ts
@@ -33,6 +33,7 @@ type YargsArgs = {
   dist: string;
   src: string;
   eval: boolean;
+  manifest?: string;
   outfileName: string;
   serve: boolean;
   directory?: string;
diff --git a/packages/snaps-cli/src/webpack/server.ts b/packages/snaps-cli/src/webpack/server.ts
index 557ec5be5f..f2e5560414 100644
--- a/packages/snaps-cli/src/webpack/server.ts
+++ b/packages/snaps-cli/src/webpack/server.ts
@@ -8,6 +8,16 @@ import { join, relative, resolve as resolvePath, sep, posix } from 'path';
 
 import type { ProcessedConfig } from '../config';
 
+/**
+ * Options for the {@link getServer} function.
+ */
+type ServerOptions = {
+  /**
+   * The path to the manifest file to serve as `/snap.manifest.json`.
+   */
+  manifestPath?: string;
+};
+
 /**
  * Get the relative path from one path to another.
  *
@@ -87,11 +97,20 @@ export function getAllowedPaths(
  *
  * @param request - The request object.
  * @param config - The config object.
+ * @param options - The server options.
+ * @param options.manifestPath - The path to the manifest file to serve as
+ * `/snap.manifest.json`.
  * @returns A promise that resolves to `true` if the path is allowed, or
  * `false` if it is not.
  */
-async function isAllowedPath(request: Request, config: ProcessedConfig) {
-  const manifestPath = join(config.server.root, NpmSnapFileNames.Manifest);
+async function isAllowedPath(
+  request: Request,
+  config: ProcessedConfig,
+  options: ServerOptions,
+) {
+  const { manifestPath = join(config.server.root, NpmSnapFileNames.Manifest) } =
+    options;
+
   const { result } = await readJsonFile<SnapManifest>(manifestPath);
   const allowedPaths = getAllowedPaths(config, result);
 
@@ -109,6 +128,9 @@ type Middleware = (app: Express) => void;
  * difficult to customize.
  *
  * @param config - The config object.
+ * @param options - The server options.
+ * @param options.manifestPath - The path to the manifest file to serve as
+ * `/snap.manifest.json`.
  * @param middleware - An array of middleware functions to run before serving
  * the static files.
  * @returns An object with a `listen` method that returns a promise that
@@ -116,8 +138,12 @@ type Middleware = (app: Express) => void;
  */
 export function getServer(
   config: ProcessedConfig,
+  options: ServerOptions = {},
   middleware: Middleware[] = [],
 ) {
+  const { manifestPath = join(config.server.root, NpmSnapFileNames.Manifest) } =
+    options;
+
   const app = express();
 
   // Run "middleware" functions before serving the static files.
@@ -125,7 +151,7 @@ export function getServer(
 
   // Check for allowed paths in the request URL.
   app.use((request, response, next) => {
-    isAllowedPath(request, config)
+    isAllowedPath(request, config, options)
       .then((allowed) => {
         if (allowed) {
           // eslint-disable-next-line promise/no-callback-in-promise
@@ -140,6 +166,14 @@ export function getServer(
       .catch(next);
   });
 
+  app.get('/snap.manifest.json', (_request, response, next) => {
+    response.sendFile(manifestPath, (error) => {
+      if (error) {
+        next(error);
+      }
+    });
+  });
+
   // Serve the static files.
   app.use(
     expressStatic(config.server.root, {
diff --git a/packages/snaps-rollup-plugin/src/plugin.ts b/packages/snaps-rollup-plugin/src/plugin.ts
index 2e932dd8a0..951c248db5 100644
--- a/packages/snaps-rollup-plugin/src/plugin.ts
+++ b/packages/snaps-rollup-plugin/src/plugin.ts
@@ -74,13 +74,10 @@ export default function snaps(options?: Partial<Options>): Plugin {
       }
 
       if (defaultOptions.manifestPath) {
-        const { reports } = await checkManifest(
-          pathUtils.dirname(defaultOptions.manifestPath),
-          {
-            updateAndWriteManifest: defaultOptions.writeManifest,
-            sourceCode: await fs.readFile(output.file, 'utf8'),
-          },
-        );
+        const { reports } = await checkManifest(defaultOptions.manifestPath, {
+          updateAndWriteManifest: defaultOptions.writeManifest,
+          sourceCode: await fs.readFile(output.file, 'utf8'),
+        });
 
         const errorsUnfixed = reports
           .filter((report) => report.severity === 'error' && !report.wasFixed)
diff --git a/packages/snaps-utils/src/manifest/manifest.ts b/packages/snaps-utils/src/manifest/manifest.ts
index 4866bf9d98..f8119d46b1 100644
--- a/packages/snaps-utils/src/manifest/manifest.ts
+++ b/packages/snaps-utils/src/manifest/manifest.ts
@@ -2,7 +2,7 @@ import { getErrorMessage } from '@metamask/snaps-sdk';
 import type { Json } from '@metamask/utils';
 import { assert, isPlainObject } from '@metamask/utils';
 import { promises as fs } from 'fs';
-import pathUtils from 'path';
+import pathUtils, { dirname } from 'path';
 
 import type { SnapManifest } from './validation';
 import type { ValidatorResults } from './validator';
@@ -92,7 +92,7 @@ export type WriteFileFunction = (path: string, data: string) => Promise<void>;
  * the fixed version to disk if `writeManifest` is true. Throws if validation
  * fails.
  *
- * @param basePath - The path to the folder with the manifest files.
+ * @param manifestPath - The path to the manifest file.
  * @param options - Additional options for the function.
  * @param options.sourceCode - The source code of the Snap.
  * @param options.writeFileFn - The function to use to write the manifest to
@@ -111,7 +111,7 @@ export type WriteFileFunction = (path: string, data: string) => Promise<void>;
  * were encountered during processing of the manifest files.
  */
 export async function checkManifest(
-  basePath: string,
+  manifestPath: string,
   {
     updateAndWriteManifest = true,
     sourceCode,
@@ -121,7 +121,7 @@ export async function checkManifest(
     watchMode = false,
   }: CheckManifestOptions = {},
 ): Promise<CheckManifestResult> {
-  const manifestPath = pathUtils.join(basePath, NpmSnapFileNames.Manifest);
+  const basePath = dirname(manifestPath);
   const manifestFile = await readJsonFile(manifestPath);
   const unvalidatedManifest = manifestFile.result;
 
@@ -188,7 +188,7 @@ export async function checkManifest(
 
       try {
         await writeFileFn(
-          pathUtils.join(basePath, NpmSnapFileNames.Manifest),
+          manifestPath,
           manifestResults.files.manifest.toString(),
         );
       } catch (error) {
diff --git a/packages/snaps-webpack-plugin/src/plugin.ts b/packages/snaps-webpack-plugin/src/plugin.ts
index 0f689c724e..99b08db4a5 100644
--- a/packages/snaps-webpack-plugin/src/plugin.ts
+++ b/packages/snaps-webpack-plugin/src/plugin.ts
@@ -187,27 +187,24 @@ export default class SnapsWebpackPlugin {
       }
 
       if (this.options.manifestPath) {
-        const { reports } = await checkManifest(
-          pathUtils.dirname(this.options.manifestPath),
-          {
-            updateAndWriteManifest: this.options.writeManifest,
-            sourceCode: bundleContent,
-            exports,
-            handlerEndowments,
-            watchMode: compiler.watchMode,
-            writeFileFn: async (path, data) => {
-              assert(
-                compiler.outputFileSystem,
-                'Expected compiler to have an output file system.',
-              );
-              return writeManifest(
-                path,
-                data,
-                promisify(compiler.outputFileSystem.writeFile),
-              );
-            },
+        const { reports } = await checkManifest(this.options.manifestPath, {
+          updateAndWriteManifest: this.options.writeManifest,
+          sourceCode: bundleContent,
+          exports,
+          handlerEndowments,
+          watchMode: compiler.watchMode,
+          writeFileFn: async (path, data) => {
+            assert(
+              compiler.outputFileSystem,
+              'Expected compiler to have an output file system.',
+            );
+            return writeManifest(
+              path,
+              data,
+              promisify(compiler.outputFileSystem.writeFile),
+            );
           },
-        );
+        });
 
         const errors = reports
           .filter((report) => report.severity === 'error' && !report.wasFixed)

From 02973859f80e6589049d8100a212326b60f8b866 Mon Sep 17 00:00:00 2001
From: Maarten Zuidhoorn <maarten@zuidhoorn.com>
Date: Thu, 8 Jan 2026 10:04:09 +0100
Subject: [PATCH 2/8] Add missing headers

---
 packages/snaps-cli/src/webpack/server.ts | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/packages/snaps-cli/src/webpack/server.ts b/packages/snaps-cli/src/webpack/server.ts
index f2e5560414..318f5ae897 100644
--- a/packages/snaps-cli/src/webpack/server.ts
+++ b/packages/snaps-cli/src/webpack/server.ts
@@ -167,11 +167,20 @@ export function getServer(
   });
 
   app.get('/snap.manifest.json', (_request, response, next) => {
-    response.sendFile(manifestPath, (error) => {
-      if (error) {
-        next(error);
-      }
-    });
+    response.sendFile(
+      manifestPath,
+      {
+        headers: {
+          'Cache-Control': 'no-cache',
+          'Access-Control-Allow-Origin': '*',
+        },
+      },
+      (error) => {
+        if (error) {
+          next(error);
+        }
+      },
+    );
   });
 
   // Serve the static files.

From dd231594660649b8ffb5a02d1d2026f6aab10356 Mon Sep 17 00:00:00 2001
From: Maarten Zuidhoorn <maarten@zuidhoorn.com>
Date: Thu, 8 Jan 2026 13:12:10 +0100
Subject: [PATCH 3/8] Simplify implementation by merging specified manifest
 before calling watch handler

---
 .../snaps-cli/src/commands/sandbox/server.ts  |  2 +-
 .../snaps-cli/src/commands/watch/index.ts     | 18 +++++++--
 .../snaps-cli/src/commands/watch/watch.ts     | 21 ++--------
 packages/snaps-cli/src/webpack/server.ts      | 38 +++----------------
 4 files changed, 24 insertions(+), 55 deletions(-)

diff --git a/packages/snaps-cli/src/commands/sandbox/server.ts b/packages/snaps-cli/src/commands/sandbox/server.ts
index 70a6e467a4..0d67fbc2f8 100644
--- a/packages/snaps-cli/src/commands/sandbox/server.ts
+++ b/packages/snaps-cli/src/commands/sandbox/server.ts
@@ -11,7 +11,7 @@ import { getServer } from '../../webpack';
  * @returns The server instance.
  */
 export async function startSandbox(config: ProcessedConfig) {
-  const server = getServer(config, {}, [
+  const server = getServer(config, [
     (app) => {
       app.use(
         '/__sandbox__',
diff --git a/packages/snaps-cli/src/commands/watch/index.ts b/packages/snaps-cli/src/commands/watch/index.ts
index eedfcb06dd..35db4c7357 100644
--- a/packages/snaps-cli/src/commands/watch/index.ts
+++ b/packages/snaps-cli/src/commands/watch/index.ts
@@ -11,11 +11,21 @@ const command = {
   builder: (yarg: yargs.Argv) => {
     yarg.option('port', builders.port).option('manifest', builders.manifest);
   },
-  handler: async (argv: YargsArgs) =>
-    watchHandler(argv.context.config, {
-      manifestPath: argv.manifest && resolve(process.cwd(), argv.manifest),
+  handler: async (argv: YargsArgs) => {
+    const configWithManifest = argv.manifest
+      ? {
+          ...argv.context.config,
+          manifest: {
+            ...argv.context.config.manifest,
+            path: resolve(process.cwd(), argv.manifest),
+          },
+        }
+      : argv.context.config;
+
+    return await watchHandler(configWithManifest, {
       port: argv.port,
-    }),
+    });
+  },
 };
 
 export * from './implementation';
diff --git a/packages/snaps-cli/src/commands/watch/watch.ts b/packages/snaps-cli/src/commands/watch/watch.ts
index 6a3cae7f6d..2e915c6293 100644
--- a/packages/snaps-cli/src/commands/watch/watch.ts
+++ b/packages/snaps-cli/src/commands/watch/watch.ts
@@ -8,11 +8,6 @@ import { executeSteps, info } from '../../utils';
 import { getServer } from '../../webpack';
 
 type WatchOptions = {
-  /**
-   * The path to the manifest file.
-   */
-  manifestPath?: string;
-
   /**
    * The port to listen on.
    */
@@ -41,7 +36,7 @@ const steps: Steps<WatchContext> = [
     name: 'Starting the development server.',
     condition: ({ config }) => config.server.enabled,
     task: async ({ config, options, spinner }) => {
-      const server = getServer(config, options);
+      const server = getServer(config);
       const { port } = await server.listen(options.port ?? config.server.port);
 
       info(`The server is listening on http://localhost:${port}.`, spinner);
@@ -49,18 +44,8 @@ const steps: Steps<WatchContext> = [
   },
   {
     name: 'Building the Snap bundle.',
-    task: async ({ config, options, spinner }) => {
-      const configWithManifest = options.manifestPath
-        ? {
-            ...config,
-            manifest: {
-              ...config.manifest,
-              path: options.manifestPath,
-            },
-          }
-        : config;
-
-      await watch(configWithManifest, { spinner });
+    task: async ({ config, spinner }) => {
+      await watch(config, { spinner });
     },
   },
 ];
diff --git a/packages/snaps-cli/src/webpack/server.ts b/packages/snaps-cli/src/webpack/server.ts
index 318f5ae897..552853c878 100644
--- a/packages/snaps-cli/src/webpack/server.ts
+++ b/packages/snaps-cli/src/webpack/server.ts
@@ -4,20 +4,10 @@ import type { Express, Request } from 'express';
 import express, { static as expressStatic } from 'express';
 import type { Server } from 'http';
 import type { AddressInfo } from 'net';
-import { join, relative, resolve as resolvePath, sep, posix } from 'path';
+import { relative, resolve as resolvePath, sep, posix } from 'path';
 
 import type { ProcessedConfig } from '../config';
 
-/**
- * Options for the {@link getServer} function.
- */
-type ServerOptions = {
-  /**
-   * The path to the manifest file to serve as `/snap.manifest.json`.
-   */
-  manifestPath?: string;
-};
-
 /**
  * Get the relative path from one path to another.
  *
@@ -97,21 +87,11 @@ export function getAllowedPaths(
  *
  * @param request - The request object.
  * @param config - The config object.
- * @param options - The server options.
- * @param options.manifestPath - The path to the manifest file to serve as
- * `/snap.manifest.json`.
  * @returns A promise that resolves to `true` if the path is allowed, or
  * `false` if it is not.
  */
-async function isAllowedPath(
-  request: Request,
-  config: ProcessedConfig,
-  options: ServerOptions,
-) {
-  const { manifestPath = join(config.server.root, NpmSnapFileNames.Manifest) } =
-    options;
-
-  const { result } = await readJsonFile<SnapManifest>(manifestPath);
+async function isAllowedPath(request: Request, config: ProcessedConfig) {
+  const { result } = await readJsonFile<SnapManifest>(config.manifest.path);
   const allowedPaths = getAllowedPaths(config, result);
 
   const path = request.path.slice(1);
@@ -128,9 +108,6 @@ type Middleware = (app: Express) => void;
  * difficult to customize.
  *
  * @param config - The config object.
- * @param options - The server options.
- * @param options.manifestPath - The path to the manifest file to serve as
- * `/snap.manifest.json`.
  * @param middleware - An array of middleware functions to run before serving
  * the static files.
  * @returns An object with a `listen` method that returns a promise that
@@ -138,12 +115,8 @@ type Middleware = (app: Express) => void;
  */
 export function getServer(
   config: ProcessedConfig,
-  options: ServerOptions = {},
   middleware: Middleware[] = [],
 ) {
-  const { manifestPath = join(config.server.root, NpmSnapFileNames.Manifest) } =
-    options;
-
   const app = express();
 
   // Run "middleware" functions before serving the static files.
@@ -151,7 +124,7 @@ export function getServer(
 
   // Check for allowed paths in the request URL.
   app.use((request, response, next) => {
-    isAllowedPath(request, config, options)
+    isAllowedPath(request, config)
       .then((allowed) => {
         if (allowed) {
           // eslint-disable-next-line promise/no-callback-in-promise
@@ -166,9 +139,10 @@ export function getServer(
       .catch(next);
   });
 
+  // Serve the manifest file at the expected URL.
   app.get('/snap.manifest.json', (_request, response, next) => {
     response.sendFile(
-      manifestPath,
+      config.manifest.path,
       {
         headers: {
           'Cache-Control': 'no-cache',

From 1e77e2be9d5c8953372160ba9d52f373f4ef2e20 Mon Sep 17 00:00:00 2001
From: Maarten Zuidhoorn <maarten@zuidhoorn.com>
Date: Thu, 8 Jan 2026 14:09:05 +0100
Subject: [PATCH 4/8] Fix existing tests

---
 packages/snaps-cli/src/webpack/server.test.ts |  6 ++++
 packages/snaps-cli/src/webpack/server.ts      |  7 +++--
 .../snaps-rollup-plugin/src/plugin.test.ts    |  4 +--
 .../snaps-utils/src/manifest/manifest.test.ts | 28 +++++++++----------
 .../snaps-webpack-plugin/src/plugin.test.ts   |  8 +++---
 5 files changed, 31 insertions(+), 22 deletions(-)

diff --git a/packages/snaps-cli/src/webpack/server.test.ts b/packages/snaps-cli/src/webpack/server.test.ts
index cf1cae39aa..1814f60582 100644
--- a/packages/snaps-cli/src/webpack/server.test.ts
+++ b/packages/snaps-cli/src/webpack/server.test.ts
@@ -207,6 +207,9 @@ describe('getServer', () => {
         root: '/foo',
         port: 0,
       },
+      manifest: {
+        path: '/foo/snap.manifest.json',
+      },
     });
 
     const server = getServer(config);
@@ -229,6 +232,9 @@ describe('getServer', () => {
         root: '/foo',
         port: 0,
       },
+      manifest: {
+        path: '/foo/snap.manifest.json',
+      },
     });
 
     const server = getServer(config);
diff --git a/packages/snaps-cli/src/webpack/server.ts b/packages/snaps-cli/src/webpack/server.ts
index 552853c878..635de2fe59 100644
--- a/packages/snaps-cli/src/webpack/server.ts
+++ b/packages/snaps-cli/src/webpack/server.ts
@@ -91,7 +91,10 @@ export function getAllowedPaths(
  * `false` if it is not.
  */
 async function isAllowedPath(request: Request, config: ProcessedConfig) {
-  const { result } = await readJsonFile<SnapManifest>(config.manifest.path);
+  const { result } = await readJsonFile<SnapManifest>(
+    resolvePath(config.server.root, config.manifest.path),
+  );
+
   const allowedPaths = getAllowedPaths(config, result);
 
   const path = request.path.slice(1);
@@ -142,7 +145,7 @@ export function getServer(
   // Serve the manifest file at the expected URL.
   app.get('/snap.manifest.json', (_request, response, next) => {
     response.sendFile(
-      config.manifest.path,
+      resolvePath(config.server.root, config.manifest.path),
       {
         headers: {
           'Cache-Control': 'no-cache',
diff --git a/packages/snaps-rollup-plugin/src/plugin.test.ts b/packages/snaps-rollup-plugin/src/plugin.test.ts
index 1e86c6d4b2..eef5b9311a 100644
--- a/packages/snaps-rollup-plugin/src/plugin.test.ts
+++ b/packages/snaps-rollup-plugin/src/plugin.test.ts
@@ -237,7 +237,7 @@ describe('snaps', () => {
     });
 
     expect(mock).toHaveBeenCalledTimes(1);
-    expect(mock).toHaveBeenCalledWith('/', {
+    expect(mock).toHaveBeenCalledWith('/snap.manifest.json', {
       updateAndWriteManifest: true,
       sourceCode: expect.any(String),
     });
@@ -260,7 +260,7 @@ describe('snaps', () => {
     });
 
     expect(mock).toHaveBeenCalledTimes(1);
-    expect(mock).toHaveBeenCalledWith('/', {
+    expect(mock).toHaveBeenCalledWith('/snap.manifest.json', {
       updateAndWriteManifest: false,
       sourceCode: expect.any(String),
     });
diff --git a/packages/snaps-utils/src/manifest/manifest.test.ts b/packages/snaps-utils/src/manifest/manifest.test.ts
index 0e2d0b3375..5ebc44410b 100644
--- a/packages/snaps-utils/src/manifest/manifest.test.ts
+++ b/packages/snaps-utils/src/manifest/manifest.test.ts
@@ -103,7 +103,7 @@ describe('checkManifest', () => {
   });
 
   it('returns the status and warnings after processing', async () => {
-    const { updated, reports } = await checkManifest(BASE_PATH);
+    const { updated, reports } = await checkManifest(MANIFEST_PATH);
     expect(reports).toHaveLength(0);
     expect(updated).toBe(false);
   });
@@ -119,7 +119,7 @@ describe('checkManifest', () => {
       ),
     );
 
-    const { files, updated, reports } = await checkManifest(BASE_PATH);
+    const { files, updated, reports } = await checkManifest(MANIFEST_PATH);
     const unfixed = reports.filter((report) => !report.wasFixed);
     const fixed = reports.filter((report) => report.wasFixed);
 
@@ -147,7 +147,7 @@ describe('checkManifest', () => {
       ),
     );
 
-    const { files, updated, reports } = await checkManifest(BASE_PATH);
+    const { files, updated, reports } = await checkManifest(MANIFEST_PATH);
     const unfixed = reports.filter((report) => !report.wasFixed);
     const fixed = reports.filter((report) => report.wasFixed);
 
@@ -180,7 +180,7 @@ describe('checkManifest', () => {
 
     await fs.writeFile(MANIFEST_PATH, JSON.stringify(manifest));
 
-    const { files, updated, reports } = await checkManifest(BASE_PATH);
+    const { files, updated, reports } = await checkManifest(MANIFEST_PATH);
     const unfixed = reports.filter((report) => !report.wasFixed);
     const fixed = reports.filter((report) => report.wasFixed);
 
@@ -228,7 +228,7 @@ describe('checkManifest', () => {
 
     await fs.writeFile(PACKAGE_JSON_PATH, JSON.stringify(packageJson));
 
-    const { updated, reports } = await checkManifest(BASE_PATH);
+    const { updated, reports } = await checkManifest(MANIFEST_PATH);
 
     const warnings = reports.filter(({ severity }) => severity === 'warning');
 
@@ -247,7 +247,7 @@ describe('checkManifest', () => {
 
     await fs.writeFile(MANIFEST_PATH, JSON.stringify(manifest));
 
-    const { reports } = await checkManifest(BASE_PATH);
+    const { reports } = await checkManifest(MANIFEST_PATH);
     const warnings = reports.filter(({ severity }) => severity === 'warning');
     expect(warnings).toHaveLength(1);
     expect(warnings[0].message).toMatch(
@@ -255,7 +255,7 @@ describe('checkManifest', () => {
     );
   });
 
-  it('returns a warning if manifest has with a non 1:1 ratio', async () => {
+  it('returns a warning if manifest has icon with a non 1:1 ratio', async () => {
     const manifest = getSnapManifest({
       platformVersion: getPlatformVersion(),
     });
@@ -266,7 +266,7 @@ describe('checkManifest', () => {
     );
     await fs.writeFile(MANIFEST_PATH, JSON.stringify(manifest));
 
-    const { reports } = await checkManifest(BASE_PATH);
+    const { reports } = await checkManifest(MANIFEST_PATH);
     const warnings = reports.filter(({ severity }) => severity === 'warning');
     expect(warnings).toHaveLength(1);
     expect(warnings[0].message).toMatch(
@@ -283,7 +283,7 @@ describe('checkManifest', () => {
 
     await fs.writeFile(MANIFEST_PATH, JSON.stringify(manifest));
 
-    const { reports } = await checkManifest(BASE_PATH, {
+    const { reports } = await checkManifest(MANIFEST_PATH, {
       updateAndWriteManifest: false,
     });
 
@@ -315,7 +315,7 @@ describe('checkManifest', () => {
       ),
     );
 
-    await expect(checkManifest(BASE_PATH)).rejects.toThrow(
+    await expect(checkManifest(MANIFEST_PATH)).rejects.toThrow(
       "Failed to read snap files: ENOENT: no such file or directory, open '/snap/foo.json'",
     );
   });
@@ -342,7 +342,7 @@ describe('checkManifest', () => {
       JSON.stringify(localizationFile),
     );
 
-    const { reports } = await checkManifest(BASE_PATH);
+    const { reports } = await checkManifest(MANIFEST_PATH);
     expect(reports.map(({ message }) => message)).toStrictEqual([
       'Failed to validate localization file "/snap/locales/en.json": At path: messages — Expected a value of type record, but received: "foo".',
     ]);
@@ -370,7 +370,7 @@ describe('checkManifest', () => {
       JSON.stringify(localizationFile),
     );
 
-    const { reports } = await checkManifest(BASE_PATH);
+    const { reports } = await checkManifest(MANIFEST_PATH);
     expect(reports.map(({ message }) => message)).toStrictEqual([
       'Failed to localize Snap manifest: Failed to translate "{{ name }}": No translation found for "name" in "en" file.',
     ]);
@@ -388,7 +388,7 @@ describe('checkManifest', () => {
     await fs.mkdir(join(BASE_PATH, 'locales'));
     await fs.writeFile(join(BASE_PATH, '/locales/en.json'), ',');
 
-    await expect(checkManifest(BASE_PATH)).rejects.toThrow(
+    await expect(checkManifest(MANIFEST_PATH)).rejects.toThrow(
       'Failed to parse localization file "/snap/locales/en.json" as JSON.',
     );
   });
@@ -401,7 +401,7 @@ describe('checkManifest', () => {
       throw new Error('foo');
     });
 
-    await expect(checkManifest(BASE_PATH)).rejects.toThrow(
+    await expect(checkManifest(MANIFEST_PATH)).rejects.toThrow(
       'Failed to update "snap.manifest.json": foo',
     );
   });
diff --git a/packages/snaps-webpack-plugin/src/plugin.test.ts b/packages/snaps-webpack-plugin/src/plugin.test.ts
index 3062638e1c..f7269f49c2 100644
--- a/packages/snaps-webpack-plugin/src/plugin.test.ts
+++ b/packages/snaps-webpack-plugin/src/plugin.test.ts
@@ -276,7 +276,7 @@ describe('SnapsWebpackPlugin', () => {
     });
 
     expect(mock).toHaveBeenCalledTimes(1);
-    expect(mock).toHaveBeenCalledWith('/', {
+    expect(mock).toHaveBeenCalledWith('/snap.manifest.json', {
       exports: undefined,
       handlerEndowments,
       updateAndWriteManifest: true,
@@ -320,7 +320,7 @@ describe('SnapsWebpackPlugin', () => {
     });
 
     expect(checkManifestMock).toHaveBeenCalledTimes(1);
-    expect(checkManifestMock).toHaveBeenCalledWith('/', {
+    expect(checkManifestMock).toHaveBeenCalledWith('/snap.manifest.json', {
       exports: ['foo'],
       handlerEndowments,
       updateAndWriteManifest: true,
@@ -347,7 +347,7 @@ describe('SnapsWebpackPlugin', () => {
     });
 
     expect(mock).toHaveBeenCalledTimes(1);
-    expect(mock).toHaveBeenCalledWith('/', {
+    expect(mock).toHaveBeenCalledWith('/snap.manifest.json', {
       exports: undefined,
       handlerEndowments,
       updateAndWriteManifest: false,
@@ -377,7 +377,7 @@ describe('SnapsWebpackPlugin', () => {
     });
 
     expect(mock).toHaveBeenCalledTimes(1);
-    expect(mock).toHaveBeenCalledWith('/', {
+    expect(mock).toHaveBeenCalledWith('/snap.manifest.json', {
       exports: undefined,
       handlerEndowments,
       updateAndWriteManifest: false,

From fbaddc36532ac48783b1491d7abe23f0e1e5a6ce Mon Sep 17 00:00:00 2001
From: Maarten Zuidhoorn <maarten@zuidhoorn.com>
Date: Fri, 9 Jan 2026 12:54:49 +0100
Subject: [PATCH 5/8] Add more tests

---
 .../src/commands/watch/index.test.ts          | 17 +++++++-
 packages/snaps-cli/src/webpack/server.test.ts | 40 +++++++++++++++++--
 packages/snaps-cli/src/webpack/server.ts      |  4 ++
 3 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/packages/snaps-cli/src/commands/watch/index.test.ts b/packages/snaps-cli/src/commands/watch/index.test.ts
index c2a225939f..355f39bb61 100644
--- a/packages/snaps-cli/src/commands/watch/index.test.ts
+++ b/packages/snaps-cli/src/commands/watch/index.test.ts
@@ -5,9 +5,10 @@ import type { YargsArgs } from '../../types/yargs';
 
 jest.mock('./watch');
 
-const getMockArgv = () => {
+const getMockArgv = (manifest?: string | undefined) => {
   return {
     context: { config: getMockConfig() },
+    manifest,
   } as unknown as YargsArgs;
 };
 
@@ -16,4 +17,18 @@ describe('watch command', () => {
     await command.handler(getMockArgv());
     expect(watchHandler).toHaveBeenCalled();
   });
+
+  it('calls the `watchHandler` function with a custom manifest path', async () => {
+    await command.handler(getMockArgv('/custom.json'));
+    expect(watchHandler).toHaveBeenCalledWith(
+      expect.objectContaining({
+        manifest: expect.objectContaining({
+          path: '/custom.json',
+        }),
+      }),
+      {
+        port: undefined,
+      },
+    );
+  });
 });
diff --git a/packages/snaps-cli/src/webpack/server.test.ts b/packages/snaps-cli/src/webpack/server.test.ts
index 1814f60582..aae2985c65 100644
--- a/packages/snaps-cli/src/webpack/server.test.ts
+++ b/packages/snaps-cli/src/webpack/server.test.ts
@@ -139,7 +139,8 @@ describe('getAllowedPaths', () => {
 
 describe('getServer', () => {
   beforeEach(async () => {
-    await fs.mkdir('/foo', { recursive: true });
+    await fs.mkdir('/foo/dist', { recursive: true });
+    await fs.writeFile('/foo/dist/bundle.js', 'console.log("Hello, world!");');
     await fs.writeFile(
       '/foo/snap.manifest.json',
       JSON.stringify(getSnapManifest()),
@@ -207,6 +208,9 @@ describe('getServer', () => {
         root: '/foo',
         port: 0,
       },
+      output: {
+        path: '/foo/dist',
+      },
       manifest: {
         path: '/foo/snap.manifest.json',
       },
@@ -216,11 +220,41 @@ describe('getServer', () => {
     const { port, close } = await server.listen();
 
     const response = await fetch(
-      `http://localhost:${port}/snap.manifest.json?_=1731493314736`,
+      `http://localhost:${port}/dist/bundle.js?_=1731493314736`,
     );
 
     expect(response.status).toBe(200);
-    expect(await response.text()).toBe(JSON.stringify(getSnapManifest()));
+    expect(await response.text()).toBe('console.log("Hello, world!");');
+
+    await close();
+  });
+
+  it('responds with a custom manifest file', async () => {
+    const config = getMockConfig({
+      input: 'src/index.js',
+      server: {
+        root: '/foo',
+        port: 0,
+      },
+      manifest: {
+        path: '/foo/snap.manifest.dev.json',
+      },
+    });
+
+    const server = getServer(config);
+    const { port, close } = await server.listen();
+
+    // Create a custom manifest file in the /foo/dist directory
+    const customManifest = getSnapManifest({ proposedName: 'Dev Snap' });
+    await fs.writeFile(
+      '/foo/snap.manifest.dev.json',
+      JSON.stringify(customManifest),
+    );
+
+    const response = await fetch(`http://localhost:${port}/snap.manifest.json`);
+
+    expect(response.status).toBe(200);
+    expect(await response.text()).toBe(JSON.stringify(customManifest));
 
     await close();
   });
diff --git a/packages/snaps-cli/src/webpack/server.ts b/packages/snaps-cli/src/webpack/server.ts
index 635de2fe59..2cc806e78a 100644
--- a/packages/snaps-cli/src/webpack/server.ts
+++ b/packages/snaps-cli/src/webpack/server.ts
@@ -152,6 +152,10 @@ export function getServer(
           'Access-Control-Allow-Origin': '*',
         },
       },
+
+      // This is complicated to test, since this middleware is only called if
+      // the file exists in the first place.
+      /* istanbul ignore next */
       (error) => {
         if (error) {
           next(error);

From 7f17dbf7bc44b308abbe38c6dba03be05cbf66bf Mon Sep 17 00:00:00 2001
From: Maarten Zuidhoorn <maarten@zuidhoorn.com>
Date: Fri, 9 Jan 2026 13:04:27 +0100
Subject: [PATCH 6/8] Fix test on Windows

---
 packages/snaps-cli/src/commands/watch/index.test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/snaps-cli/src/commands/watch/index.test.ts b/packages/snaps-cli/src/commands/watch/index.test.ts
index 355f39bb61..2fd9e2c5ec 100644
--- a/packages/snaps-cli/src/commands/watch/index.test.ts
+++ b/packages/snaps-cli/src/commands/watch/index.test.ts
@@ -23,7 +23,7 @@ describe('watch command', () => {
     expect(watchHandler).toHaveBeenCalledWith(
       expect.objectContaining({
         manifest: expect.objectContaining({
-          path: '/custom.json',
+          path: expect.stringContaining('custom.json'),
         }),
       }),
       {

From 5fb414f4312c4ee22da238b55b744ced005ceae7 Mon Sep 17 00:00:00 2001
From: Maarten Zuidhoorn <maarten@zuidhoorn.com>
Date: Fri, 9 Jan 2026 13:58:47 +0100
Subject: [PATCH 7/8] Attempt to fix Windows compatibility

---
 .../src/commands/manifest/implementation.test.ts         | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/packages/snaps-cli/src/commands/manifest/implementation.test.ts b/packages/snaps-cli/src/commands/manifest/implementation.test.ts
index cee6b4d91e..89c02d9b42 100644
--- a/packages/snaps-cli/src/commands/manifest/implementation.test.ts
+++ b/packages/snaps-cli/src/commands/manifest/implementation.test.ts
@@ -8,6 +8,7 @@ import {
 import type { SemVerVersion } from '@metamask/utils';
 import normalFs from 'fs';
 import ora from 'ora';
+import { join } from 'path';
 
 import { manifest } from './implementation';
 import type * as webpack from '../../webpack';
@@ -74,7 +75,7 @@ describe('manifest', () => {
 
     const spinner = ora();
     const result = await manifest(
-      '/snap/snap.manifest.json',
+      join('/snap', 'snap.manifest.json'),
       false,
       undefined,
       spinner,
@@ -97,7 +98,7 @@ describe('manifest', () => {
 
     const spinner = ora();
     const result = await manifest(
-      '/snap/snap.manifest.json',
+      join('/snap', 'snap.manifest.json'),
       false,
       undefined,
       spinner,
@@ -132,7 +133,7 @@ describe('manifest', () => {
 
     const spinner = ora();
     const result = await manifest(
-      '/snap/snap.manifest.json',
+      join('/snap', 'snap.manifest.json'),
       true,
       undefined,
       spinner,
@@ -155,7 +156,7 @@ describe('manifest', () => {
     const log = jest.spyOn(console, 'log').mockImplementation();
 
     await fs.writeFile(
-      '/snap/snap.manifest.json',
+      join('/snap', 'snap.manifest.json'),
       JSON.stringify(
         getSnapManifest({
           shasum: 'G/W5b2JZVv+epgNX9pkN63X6Lye9EJVJ4NLSgAw/afd=',

From ef52e02b0eac4d560d67608bcfc2a59fd8e6a7ea Mon Sep 17 00:00:00 2001
From: Maarten Zuidhoorn <maarten@zuidhoorn.com>
Date: Fri, 9 Jan 2026 14:58:20 +0100
Subject: [PATCH 8/8] Add temporary debug log

---
 packages/snaps-cli/src/commands/manifest/implementation.ts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/packages/snaps-cli/src/commands/manifest/implementation.ts b/packages/snaps-cli/src/commands/manifest/implementation.ts
index 608e864390..dc07f27938 100644
--- a/packages/snaps-cli/src/commands/manifest/implementation.ts
+++ b/packages/snaps-cli/src/commands/manifest/implementation.ts
@@ -4,6 +4,7 @@ import { writeManifest } from '@metamask/snaps-webpack-plugin';
 import { assert } from '@metamask/utils';
 import { red, yellow, green } from 'chalk';
 import type { Ora } from 'ora';
+import { dirname } from 'path';
 
 import { error, info, warn } from '../../utils';
 
@@ -25,6 +26,11 @@ export async function manifest(
   exports?: string[],
   spinner?: Ora,
 ): Promise<boolean> {
+  /* eslint-disable no-console */
+  console.log('Checking manifest at path:', path);
+  console.log('Dirname:', dirname(path));
+  /* eslint-enable no-console */
+
   const { reports, updated } = await checkManifest(path, {
     exports,
     handlerEndowments,