From c31c31fc258f8b733b677216d492b7655af45c0d Mon Sep 17 00:00:00 2001
From: Kris Kowal <kris@agoric.com>
Date: Tue, 5 Nov 2024 11:08:40 -0800
Subject: [PATCH 1/6] feat(compartment-mapper): languageForExtensions options
 but parameterized on package type

---
 packages/compartment-mapper/NEWS.md           |   7 +
 packages/compartment-mapper/src/archive.js    | 116 ++++++++++--
 packages/compartment-mapper/src/bundle.js     |  16 +-
 packages/compartment-mapper/src/import.js     |  29 ++-
 packages/compartment-mapper/src/map-parser.js |   8 +
 .../compartment-mapper/src/node-modules.js    | 175 +++++++++++-------
 packages/compartment-mapper/src/parse-json.js |   1 +
 .../compartment-mapper/src/types/external.ts  |   4 +
 .../compartment-mapper/test/_parse-jsonp.js   |  45 +++++
 .../node_modules/commonjs-app/module.xsonp    |   1 +
 .../node_modules/commonjs-app/package.json    |   7 +
 .../node_modules/module-app/module.xsonp      |   1 +
 .../node_modules/module-app/package.json      |   7 +
 .../node_modules/parsers-app/module.xsonp     |   1 +
 .../node_modules/parsers-app/package.json     |   9 +
 .../test/language-for-extension.test.js       | 110 +++++++++++
 packages/compartment-mapper/test/scaffold.js  |  53 ++++++
 17 files changed, 499 insertions(+), 91 deletions(-)
 create mode 100644 packages/compartment-mapper/test/_parse-jsonp.js
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/package.json
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/package.json
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/parsers-app/module.xsonp
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/parsers-app/package.json
 create mode 100644 packages/compartment-mapper/test/language-for-extension.test.js

diff --git a/packages/compartment-mapper/NEWS.md b/packages/compartment-mapper/NEWS.md
index 968df14ef1..8d37eb98e0 100644
--- a/packages/compartment-mapper/NEWS.md
+++ b/packages/compartment-mapper/NEWS.md
@@ -2,6 +2,13 @@ User-visible changes to `@endo/compartment-mapper`:
 
 # Next version
 
+- Adds options `languageForExtension`, `moduleLanguageForExtension`,
+  `commonjsLanguageForExtension`, and `languages` to `mapNodeModules` and
+  `compartmentMapForNodeModules` allowing for certain mappings from extension
+  (e.g., `ts`) to language (e.g., `mts` or `cts`) to depend on the each
+  package’s `type` in the way we already vary `js` between `cjs` and `mjs`.
+  These options enter through the high level functions including `makeArchive`
+  and `importLocation`.
 - Omits unused module descriptors from `compartment-map.json` in archived
   applications, potentially reducing file sizes.
 - Fixes an issue where errors thrown from exit module hooks (`importHook`) would
diff --git a/packages/compartment-mapper/src/archive.js b/packages/compartment-mapper/src/archive.js
index fafb0615be..992449b25f 100644
--- a/packages/compartment-mapper/src/archive.js
+++ b/packages/compartment-mapper/src/archive.js
@@ -47,7 +47,8 @@ const assignParserForLanguage = (options = {}) => {
   const parserForLanguage = freeze(
     assign(create(null), defaultParserForLanguage, parserForLanguageOption),
   );
-  return { ...rest, parserForLanguage };
+  const languages = Object.keys(parserForLanguage);
+  return { ...rest, parserForLanguage, languages };
 };
 
 /**
@@ -61,12 +62,16 @@ export const makeAndHashArchive = async (
   moduleLocation,
   options = {},
 ) => {
-  const compartmentMap = await mapNodeModules(powers, moduleLocation, options);
-  return makeAndHashArchiveFromMap(
-    powers,
-    compartmentMap,
-    assignParserForLanguage(options),
-  );
+  const { parserForLanguage, languages, ...otherOptions } =
+    assignParserForLanguage(options);
+  const compartmentMap = await mapNodeModules(powers, moduleLocation, {
+    languages,
+    ...otherOptions,
+  });
+  return makeAndHashArchiveFromMap(powers, compartmentMap, {
+    parserForLanguage,
+    ...otherOptions,
+  });
 };
 
 /**
@@ -76,20 +81,35 @@ export const makeAndHashArchive = async (
  * @returns {Promise<Uint8Array>}
  */
 export const makeArchive = async (powers, moduleLocation, options = {}) => {
-  const { dev, tags, conditions = tags, commonDependencies, policy } = options;
-
+  const {
+    dev,
+    tags,
+    conditions = tags,
+    commonDependencies,
+    policy,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
+    parserForLanguage,
+    languages,
+    ...otherOptions
+  } = assignParserForLanguage(options);
   const compartmentMap = await mapNodeModules(powers, moduleLocation, {
     dev,
     conditions,
     commonDependencies,
     policy,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
+    languages,
   });
 
-  return makeArchiveFromMap(
-    powers,
-    compartmentMap,
-    assignParserForLanguage(options),
-  );
+  return makeArchiveFromMap(powers, compartmentMap, {
+    parserForLanguage,
+    policy,
+    ...otherOptions,
+  });
 };
 
 /**
@@ -99,16 +119,36 @@ export const makeArchive = async (powers, moduleLocation, options = {}) => {
  * @returns {Promise<Uint8Array>}
  */
 export const mapLocation = async (powers, moduleLocation, options = {}) => {
-  const { dev, tags, conditions = tags, commonDependencies, policy } = options;
+  const {
+    dev,
+    tags,
+    conditions = tags,
+    commonDependencies,
+    policy,
+    parserForLanguage,
+    languages,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
+    ...otherOptions
+  } = assignParserForLanguage(options);
 
   const compartmentMap = await mapNodeModules(powers, moduleLocation, {
     dev,
     conditions,
     commonDependencies,
     policy,
+    languages,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
   });
 
-  return mapFromMap(powers, compartmentMap, assignParserForLanguage(options));
+  return mapFromMap(powers, compartmentMap, {
+    parserForLanguage,
+    policy,
+    ...otherOptions,
+  });
 };
 
 /**
@@ -118,16 +158,36 @@ export const mapLocation = async (powers, moduleLocation, options = {}) => {
  * @returns {Promise<string>}
  */
 export const hashLocation = async (powers, moduleLocation, options = {}) => {
-  const { dev, tags, conditions = tags, commonDependencies, policy } = options;
+  const {
+    dev,
+    tags,
+    conditions = tags,
+    commonDependencies,
+    policy,
+    parserForLanguage,
+    languages,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
+    ...otherOptions
+  } = assignParserForLanguage(options);
 
   const compartmentMap = await mapNodeModules(powers, moduleLocation, {
     dev,
     conditions,
     commonDependencies,
     policy,
+    languages,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
   });
 
-  return hashFromMap(powers, compartmentMap, assignParserForLanguage(options));
+  return hashFromMap(powers, compartmentMap, {
+    parserForLanguage,
+    policy,
+    ...otherOptions,
+  });
 };
 
 /**
@@ -144,18 +204,34 @@ export const writeArchive = async (
   moduleLocation,
   options = {},
 ) => {
-  const { dev, tags, conditions = tags, commonDependencies, policy } = options;
+  const {
+    dev,
+    tags,
+    conditions = tags,
+    commonDependencies,
+    policy,
+    parserForLanguage,
+    languages,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
+    ...otherOptions
+  } = assignParserForLanguage(options);
   const compartmentMap = await mapNodeModules(readPowers, moduleLocation, {
     dev,
     conditions,
     commonDependencies,
     policy,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
+    languages,
   });
   return writeArchiveFromMap(
     write,
     readPowers,
     archiveLocation,
     compartmentMap,
-    assignParserForLanguage(options),
+    { policy, parserForLanguage, ...otherOptions },
   );
 };
diff --git a/packages/compartment-mapper/src/bundle.js b/packages/compartment-mapper/src/bundle.js
index 29f5d60e78..3884db3bb8 100644
--- a/packages/compartment-mapper/src/bundle.js
+++ b/packages/compartment-mapper/src/bundle.js
@@ -235,6 +235,8 @@ export const makeBundle = async (readPowers, moduleLocation, options) => {
     sourceMapHook = undefined,
     parserForLanguage: parserForLanguageOption = {},
     languageForExtension: languageForExtensionOption = {},
+    commonjsLanguageForExtension: commonjsLanguageForExtensionOption = {},
+    moduleLanguageForExtension: moduleLanguageForExtensionOption = {},
   } = options || {};
   const conditions = new Set(conditionsOption);
 
@@ -248,6 +250,12 @@ export const makeBundle = async (readPowers, moduleLocation, options) => {
   const languageForExtension = Object.freeze(
     Object.assign(Object.create(null), languageForExtensionOption),
   );
+  const commonjsLanguageForExtension = Object.freeze(
+    Object.assign(Object.create(null), commonjsLanguageForExtensionOption),
+  );
+  const moduleLanguageForExtension = Object.freeze(
+    Object.assign(Object.create(null), moduleLanguageForExtensionOption),
+  );
 
   const {
     packageLocation,
@@ -266,7 +274,13 @@ export const makeBundle = async (readPowers, moduleLocation, options) => {
     conditions,
     packageDescriptor,
     moduleSpecifier,
-    { dev, commonDependencies },
+    {
+      dev,
+      commonDependencies,
+      languageForExtension,
+      commonjsLanguageForExtension,
+      moduleLanguageForExtension,
+    },
   );
 
   const {
diff --git a/packages/compartment-mapper/src/import.js b/packages/compartment-mapper/src/import.js
index 754d94987b..faf7c48bc3 100644
--- a/packages/compartment-mapper/src/import.js
+++ b/packages/compartment-mapper/src/import.js
@@ -42,7 +42,8 @@ const assignParserForLanguage = (options = {}) => {
   const parserForLanguage = freeze(
     assign(create(null), defaultParserForLanguage, parserForLanguageOption),
   );
-  return { ...rest, parserForLanguage };
+  const languages = Object.keys(parserForLanguage);
+  return { ...rest, parserForLanguage, languages };
 };
 
 /**
@@ -72,7 +73,18 @@ export const loadLocation = async (
   moduleLocation,
   options = {},
 ) => {
-  const { dev, tags, commonDependencies, policy } = options;
+  const {
+    dev,
+    tags,
+    commonDependencies,
+    policy,
+    parserForLanguage,
+    languages,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
+    ...otherOptions
+  } = assignParserForLanguage(options);
   // conditions are not present in SyncArchiveOptions
   const conditions =
     'conditions' in options ? options.conditions || tags : tags;
@@ -81,12 +93,15 @@ export const loadLocation = async (
     conditions,
     commonDependencies,
     policy,
+    languageForExtension,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
+    languages,
+  });
+  return loadFromMap(readPowers, compartmentMap, {
+    parserForLanguage,
+    ...otherOptions,
   });
-  return loadFromMap(
-    readPowers,
-    compartmentMap,
-    assignParserForLanguage(options),
-  );
 };
 
 /**
diff --git a/packages/compartment-mapper/src/map-parser.js b/packages/compartment-mapper/src/map-parser.js
index 74dc243c0e..49b2acfa66 100644
--- a/packages/compartment-mapper/src/map-parser.js
+++ b/packages/compartment-mapper/src/map-parser.js
@@ -101,6 +101,14 @@ const makeExtensionParser = (
     ) {
       language = languageForModuleSpecifier[specifier];
     } else {
+      // We should revisit this design decision:
+      // Defaulting the language to the extension conflates those namespaces.
+      // So, a transform keyed by extension can be used to coerce a language
+      // (e.g., .mts to mjs) as a shorthand for configuring a parser for that
+      // extension that pre-processes the file before handing off to the
+      // parser.
+      // But, this forces us to support the case of using weird language
+      // names like pre-mjs-json as valid, unconfigured extensions.
       language = languageForExtension[extension] || extension;
     }
 
diff --git a/packages/compartment-mapper/src/node-modules.js b/packages/compartment-mapper/src/node-modules.js
index 1a0803e07a..f8754c681c 100644
--- a/packages/compartment-mapper/src/node-modules.js
+++ b/packages/compartment-mapper/src/node-modules.js
@@ -57,6 +57,13 @@
  * modules.
  */
 
+/**
+ * @typedef {object} LanguageOptions
+ * @property {LanguageForExtension} commonjsLanguageForExtension
+ * @property {LanguageForExtension} moduleLanguageForExtension
+ * @property {Set<string>} languages
+ */
+
 /**
  * @typedef {Record<string, {spec: string, alias: string}>} CommonDependencyDescriptors
  */
@@ -189,83 +196,73 @@ const findPackage = async (readDescriptor, canonical, directory, name) => {
   }
 };
 
-const defaultLanguages = /** @type {const} */ ([
-  'mjs',
-  'cjs',
-  'json',
-  'text',
-  'bytes',
-]);
-const defaultUncontroversialParsers = /** @type {const} */ ({
-  cjs: 'cjs',
+const defaultLanguageForExtension = /** @type {const} */ ({
   mjs: 'mjs',
+  cjs: 'cjs',
   json: 'json',
   text: 'text',
   bytes: 'bytes',
 });
-const defaultCommonParsers = /** @type {const} */ ({
+const defaultCommonjsLanguageForExtension = /** @type {const} */ ({
   js: 'cjs',
-  ...defaultUncontroversialParsers,
 });
-const defaultModuleParsers = /** @type {const} */ ({
+const defaultModuleLanguageForExtension = /** @type {const} */ ({
   js: 'mjs',
-  ...defaultUncontroversialParsers,
 });
 
 /**
  * @param {object} descriptor
  * @param {string} location
- * @param {object} [options]
- * @param {readonly string[]|string[]} [options.languages]
- * @param {Record<string, string>} [options.uncontroversialParsers]
- * @param {Record<string, string>} [options.commonParsers]
- * @param {Record<string, string>} [options.moduleParsers]
+ * @param {LanguageOptions} languageOptions
  * @returns {Record<string, string>}
  */
-const inferParsers = (
-  descriptor,
-  location,
-  {
-    languages = defaultLanguages,
-    uncontroversialParsers = defaultUncontroversialParsers,
-    commonParsers = defaultCommonParsers,
-    moduleParsers = defaultModuleParsers,
-  } = {},
-) => {
-  const { type, module, parsers } = descriptor;
-  let additionalParsers = Object.create(null);
-  if (parsers !== undefined) {
-    if (typeof parsers !== 'object') {
-      throw Error(
-        `Cannot interpret parser map ${JSON.stringify(
-          parsers,
-        )} of package at ${location}, must be an object mapping file extensions to corresponding languages (mjs for ECMAScript modules, cjs for CommonJS modules, or json for JSON modules`,
-      );
-    }
-    const invalidLanguages = values(parsers).filter(
-      language => !languages.includes(language),
+const inferParsers = (descriptor, location, languageOptions) => {
+  const {
+    languages,
+    moduleLanguageForExtension,
+    commonjsLanguageForExtension,
+  } = languageOptions;
+
+  const {
+    type,
+    module,
+    parsers: packageLanguageForExtension = {},
+  } = descriptor;
+
+  // Validate package-local "parsers"
+  if (
+    typeof packageLanguageForExtension !== 'object' ||
+    packageLanguageForExtension === null
+  ) {
+    throw Error(
+      `Cannot interpret parser map ${JSON.stringify(
+        packageLanguageForExtension,
+      )} of package at ${location}, must be an object mapping file extensions to corresponding languages (for example, mjs for ECMAScript modules, cjs for CommonJS modules, or json for JSON modules`,
+    );
+  }
+  const invalidLanguages = values(packageLanguageForExtension).filter(
+    language => !languages.has(language),
+  );
+  if (invalidLanguages.length > 0) {
+    throw Error(
+      `Cannot interpret parser map language values ${JSON.stringify(
+        invalidLanguages,
+      )} of package at ${location}, must be an object mapping file extensions to corresponding languages (for example, mjs for ECMAScript modules, cjs for CommonJS modules, or json for JSON modules`,
     );
-    if (invalidLanguages.length > 0) {
-      throw Error(
-        `Cannot interpret parser map language values ${JSON.stringify(
-          invalidLanguages,
-        )} of package at ${location}, must be an object mapping file extensions to corresponding languages (mjs for ECMAScript modules, cjs for CommonJS modules, or json for JSON modules`,
-      );
-    }
-    additionalParsers = { ...uncontroversialParsers, ...parsers };
   }
+
   if (type === 'module' || module !== undefined) {
-    return { ...moduleParsers, ...additionalParsers };
+    return { ...moduleLanguageForExtension, ...packageLanguageForExtension };
   }
   if (type === 'commonjs') {
-    return { ...commonParsers, ...additionalParsers };
+    return { ...commonjsLanguageForExtension, ...packageLanguageForExtension };
   }
   if (type !== undefined) {
     throw Error(
       `Cannot infer parser map for package of type ${type} at ${location}`,
     );
   }
-  return { ...commonParsers, ...additionalParsers };
+  return { ...commonjsLanguageForExtension, ...packageLanguageForExtension };
 };
 
 /**
@@ -286,6 +283,7 @@ const inferParsers = (
  * @param {Set<string>} conditions
  * @param {boolean | undefined} dev
  * @param {CommonDependencyDescriptors} commonDependencyDescriptors
+ * @param {LanguageOptions} languageOptions
  * @param {Map<string, Array<string>>} preferredPackageLogicalPathMap
  * @param {Array<string>} logicalPath
  * @returns {Promise<undefined>}
@@ -299,6 +297,7 @@ const graphPackage = async (
   conditions,
   dev,
   commonDependencyDescriptors,
+  languageOptions,
   preferredPackageLogicalPathMap = new Map(),
   logicalPath = [],
 ) => {
@@ -368,6 +367,7 @@ const graphPackage = async (
         name,
         conditions,
         preferredPackageLogicalPathMap,
+        languageOptions,
         childLogicalPath,
         optional,
         commonDependencyDescriptors,
@@ -399,6 +399,12 @@ const graphPackage = async (
     types,
   );
 
+  const parsers = inferParsers(
+    packageDescriptor,
+    packageLocation,
+    languageOptions,
+  );
+
   Object.assign(result, {
     name,
     path: logicalPath,
@@ -408,7 +414,7 @@ const graphPackage = async (
     internalAliases,
     dependencyLocations,
     types,
-    parsers: inferParsers(packageDescriptor, packageLocation),
+    parsers,
   });
 
   await Promise.all(
@@ -462,6 +468,7 @@ const graphPackage = async (
  * @param {string} name - name of the package of interest.
  * @param {Set<string>} conditions
  * @param {Map<string, Array<string>>} preferredPackageLogicalPathMap
+ * @param {LanguageOptions} languageOptions
  * @param {Array<string>} [childLogicalPath]
  * @param {boolean} [optional] - whether the dependency is optional
  * @param {object} [commonDependencyDescriptors] - dependencies to be added to all packages
@@ -475,6 +482,7 @@ const gatherDependency = async (
   name,
   conditions,
   preferredPackageLogicalPathMap,
+  languageOptions,
   childLogicalPath = [],
   optional = false,
   commonDependencyDescriptors = undefined,
@@ -511,6 +519,7 @@ const gatherDependency = async (
     conditions,
     false,
     commonDependencyDescriptors,
+    languageOptions,
     preferredPackageLogicalPathMap,
     childLogicalPath,
   );
@@ -533,7 +542,8 @@ const gatherDependency = async (
  * package.json, which was already read when searching for the package.json.
  * @param {boolean|undefined} dev - whether to use devDependencies from this package (and
  * only this package).
- * @param {Record<string,string>} [commonDependencies] - dependencies to be added to all packages
+ * @param {Record<string,string>} commonDependencies - dependencies to be added to all packages
+ * @param {LanguageOptions} languageOptions
  */
 const graphPackages = async (
   maybeRead,
@@ -542,7 +552,8 @@ const graphPackages = async (
   conditions,
   mainPackageDescriptor,
   dev,
-  commonDependencies = {},
+  commonDependencies,
+  languageOptions,
 ) => {
   const memo = create(null);
   /**
@@ -599,6 +610,7 @@ const graphPackages = async (
     conditions,
     dev,
     commonDependencyDescriptors,
+    languageOptions,
   );
   return graph;
 };
@@ -754,6 +766,46 @@ const translateGraph = (
   };
 };
 
+/**
+ * @param {Pick<MapNodeModulesOptions,
+ *   'languageForExtension' |
+ *   'moduleLanguageForExtension' |
+ *   'commonjsLanguageForExtension' |
+ *   'languages'
+ * >} options
+ */
+const makeLanguageOptions = ({
+  languageForExtension: additionalLanguageForExtension = {},
+  moduleLanguageForExtension: additionalModuleLanguageForExtension = {},
+  commonjsLanguageForExtension: additionalCommonjsLanguageForExtension = {},
+  languages: additionalLanguages = [],
+}) => {
+  const commonjsLanguageForExtension = {
+    ...defaultLanguageForExtension,
+    ...additionalLanguageForExtension,
+    ...defaultCommonjsLanguageForExtension,
+    ...additionalCommonjsLanguageForExtension,
+  };
+  const moduleLanguageForExtension = {
+    ...defaultLanguageForExtension,
+    ...additionalLanguageForExtension,
+    ...defaultModuleLanguageForExtension,
+    ...additionalModuleLanguageForExtension,
+  };
+
+  const languages = new Set([
+    ...Object.values(moduleLanguageForExtension),
+    ...Object.values(commonjsLanguageForExtension),
+    ...additionalLanguages,
+  ]);
+
+  return {
+    languages,
+    commonjsLanguageForExtension,
+    moduleLanguageForExtension,
+  };
+};
+
 /**
  * @param {ReadFn | ReadPowers | MaybeReadPowers} readPowers
  * @param {string} packageLocation
@@ -771,8 +823,10 @@ export const compartmentMapForNodeModules = async (
   moduleSpecifier,
   options = {},
 ) => {
-  const { dev = undefined, commonDependencies, policy } = options;
+  const { dev = undefined, commonDependencies = {}, policy } = options;
   const { maybeRead, canonical } = unpackReadPowers(readPowers);
+  const languageOptions = makeLanguageOptions(options);
+
   const graph = await graphPackages(
     maybeRead,
     canonical,
@@ -781,6 +835,7 @@ export const compartmentMapForNodeModules = async (
     packageDescriptor,
     dev,
     commonDependencies,
+    languageOptions,
   );
 
   if (policy) {
@@ -821,13 +876,7 @@ export const mapNodeModules = async (
   moduleLocation,
   options = {},
 ) => {
-  const {
-    tags = new Set(),
-    conditions = tags,
-    dev = undefined,
-    commonDependencies,
-    policy,
-  } = options;
+  const { tags = new Set(), conditions = tags, ...otherOptions } = options;
 
   const {
     packageLocation,
@@ -847,6 +896,6 @@ export const mapNodeModules = async (
     conditions,
     packageDescriptor,
     moduleSpecifier,
-    { dev, commonDependencies, policy },
+    otherOptions,
   );
 };
diff --git a/packages/compartment-mapper/src/parse-json.js b/packages/compartment-mapper/src/parse-json.js
index 54fe440c9f..6d9119facc 100644
--- a/packages/compartment-mapper/src/parse-json.js
+++ b/packages/compartment-mapper/src/parse-json.js
@@ -20,6 +20,7 @@ const textDecoder = new TextDecoder();
 /** @type {ParseFn} */
 export const parseJson = (bytes, _specifier, location, _packageLocation) => {
   const source = textDecoder.decode(bytes);
+  /** @type {Array<string>} */
   const imports = freeze([]);
 
   /**
diff --git a/packages/compartment-mapper/src/types/external.ts b/packages/compartment-mapper/src/types/external.ts
index c1282763bc..33f261ae5a 100644
--- a/packages/compartment-mapper/src/types/external.ts
+++ b/packages/compartment-mapper/src/types/external.ts
@@ -72,6 +72,10 @@ type MapNodeModulesOptionsOmitPolicy = Partial<{
   commonDependencies: Record<string, string>;
   /** Maps extensions to languages for all packages, like `txt` to `text` */
   languageForExtension: LanguageForExtension;
+  /** Maps extensions to languages for all type=module packages */
+  moduleLanguageForExtension: LanguageForExtension;
+  /** Maps extensions to languages for all type=commonjs packages (default) */
+  commonjsLanguageForExtension: LanguageForExtension;
   /**
    * Accounts for languages not present as values in any of the extension to
    * language mappings.
diff --git a/packages/compartment-mapper/test/_parse-jsonp.js b/packages/compartment-mapper/test/_parse-jsonp.js
new file mode 100644
index 0000000000..5bb7448742
--- /dev/null
+++ b/packages/compartment-mapper/test/_parse-jsonp.js
@@ -0,0 +1,45 @@
+/** @module Provides joke language support for importing JSONP modules. */
+
+/**
+ * @import {ParseFn, ParserImplementation} from '../src/types.js'
+ */
+
+const textDecoder = new TextDecoder();
+
+/** @type {ParseFn} */
+export const parseJsonp = (bytes, _specifier, _location, _packageLocation) => {
+  // Presumes that all JSONP module bytes are retrieved with ?callback=exports.
+  const source = textDecoder.decode(bytes);
+  const imports = harden([]);
+
+  /**
+   * @param {object} exports
+   */
+  const execute = exports => {
+    const compartment = new Compartment({
+      __options__: true,
+      globals: harden({
+        exports(value) {
+          exports.default = value;
+        },
+      }),
+    });
+    compartment.evaluate(source);
+  };
+  return {
+    parser: 'jsonp',
+    bytes,
+    record: harden({
+      imports,
+      exports: ['default'],
+      execute,
+    }),
+  };
+};
+
+/** @type {ParserImplementation} */
+export default {
+  parse: parseJsonp,
+  heuristicImports: false,
+  synchronous: true,
+};
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp
new file mode 100644
index 0000000000..f1dad2cdf6
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp
@@ -0,0 +1 @@
+exports({ meaning: 42 });
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/package.json b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/package.json
new file mode 100644
index 0000000000..cec862f1c0
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/package.json
@@ -0,0 +1,7 @@
+{
+  "name": "app",
+  "type": "commonjs",
+  "scripts": {
+    "preinstall": "echo DO NOT INSTALL TEST FIXTURES; exit -1"
+  }
+}
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp
new file mode 100644
index 0000000000..f1dad2cdf6
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp
@@ -0,0 +1 @@
+exports({ meaning: 42 });
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/package.json b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/package.json
new file mode 100644
index 0000000000..68d335f7bd
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/package.json
@@ -0,0 +1,7 @@
+{
+  "name": "app",
+  "type": "module",
+  "scripts": {
+    "preinstall": "echo DO NOT INSTALL TEST FIXTURES; exit -1"
+  }
+}
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/parsers-app/module.xsonp b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/parsers-app/module.xsonp
new file mode 100644
index 0000000000..f1dad2cdf6
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/parsers-app/module.xsonp
@@ -0,0 +1 @@
+exports({ meaning: 42 });
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/parsers-app/package.json b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/parsers-app/package.json
new file mode 100644
index 0000000000..8004f6bd58
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/node_modules/parsers-app/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "app",
+  "parsers": {
+    "xsonp": "jsonp"
+  },
+  "scripts": {
+    "preinstall": "echo DO NOT INSTALL TEST FIXTURES; exit -1"
+  }
+}
diff --git a/packages/compartment-mapper/test/language-for-extension.test.js b/packages/compartment-mapper/test/language-for-extension.test.js
new file mode 100644
index 0000000000..591cae76d3
--- /dev/null
+++ b/packages/compartment-mapper/test/language-for-extension.test.js
@@ -0,0 +1,110 @@
+import 'ses';
+import test from 'ava';
+import { scaffold } from './scaffold.js';
+import jsonp from './_parse-jsonp.js';
+
+// The JSONP parser uses harden, as a bit.
+lockdown({
+  errorTaming: 'unsafe',
+  errorTrapping: 'none',
+});
+
+scaffold(
+  'languageForExtension',
+  test,
+  new URL(
+    'fixtures-language-for-extension/node_modules/module-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  (t, { namespace }) => {
+    t.deepEqual(namespace, {
+      default: {
+        meaning: 42,
+      },
+      __proto__: {
+        __proto__: null,
+        [Symbol.toStringTag]: 'Module',
+      },
+    });
+  },
+  1,
+  {
+    parserForLanguage: { jsonp },
+    languageForExtension: { xsonp: 'jsonp' },
+  },
+);
+
+scaffold(
+  'moduleLanguageForExtension',
+  test,
+  new URL(
+    'fixtures-language-for-extension/node_modules/module-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  (t, { namespace }) => {
+    t.deepEqual(namespace, {
+      default: {
+        meaning: 42,
+      },
+      __proto__: {
+        __proto__: null,
+        [Symbol.toStringTag]: 'Module',
+      },
+    });
+  },
+  1,
+  {
+    parserForLanguage: { jsonp },
+    moduleLanguageForExtension: { xsonp: 'jsonp' },
+  },
+);
+
+scaffold(
+  'commonjsLanguageForExtension',
+  test,
+  new URL(
+    'fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  (t, { namespace }) => {
+    t.deepEqual(namespace, {
+      default: {
+        meaning: 42,
+      },
+      __proto__: {
+        __proto__: null,
+        [Symbol.toStringTag]: 'Module',
+      },
+    });
+  },
+  1,
+  {
+    parserForLanguage: { jsonp },
+    commonjsLanguageForExtension: { xsonp: 'jsonp' },
+  },
+);
+
+scaffold(
+  'package.json parsers override languageForExtension',
+  test,
+  new URL(
+    'fixtures-language-for-extension/node_modules/parsers-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  (t, { namespace }) => {
+    t.deepEqual(namespace, {
+      default: {
+        meaning: 42,
+      },
+      __proto__: {
+        __proto__: null,
+        [Symbol.toStringTag]: 'Module',
+      },
+    });
+  },
+  1,
+  {
+    parserForLanguage: { jsonp },
+    languageForExtension: { xsonp: 'text' },
+  },
+);
diff --git a/packages/compartment-mapper/test/scaffold.js b/packages/compartment-mapper/test/scaffold.js
index 467d965ff1..de99135b02 100644
--- a/packages/compartment-mapper/test/scaffold.js
+++ b/packages/compartment-mapper/test/scaffold.js
@@ -90,6 +90,10 @@ export function scaffold(
     conditions = tags,
     searchSuffixes = undefined,
     commonDependencies = undefined,
+    parserForLanguage = undefined,
+    languageForExtension = undefined,
+    commonjsLanguageForExtension = undefined,
+    moduleLanguageForExtension = undefined,
     additionalOptions = {},
   } = {},
 ) {
@@ -133,6 +137,10 @@ export function scaffold(
       conditions: new Set(['development', ...(conditions || [])]),
       searchSuffixes,
       commonDependencies,
+      parserForLanguage,
+      languageForExtension,
+      commonjsLanguageForExtension,
+      moduleLanguageForExtension,
       ...additionalOptions,
     });
     const { namespace } = await application.import({
@@ -156,6 +164,10 @@ export function scaffold(
       conditions: new Set(['development', ...(conditions || [])]),
       searchSuffixes,
       commonDependencies,
+      parserForLanguage,
+      languageForExtension,
+      commonjsLanguageForExtension,
+      moduleLanguageForExtension,
       ...additionalOptions,
     });
     return namespace;
@@ -173,6 +185,10 @@ export function scaffold(
         conditions: new Set(['development', ...(conditions || [])]),
         searchSuffixes,
         commonDependencies,
+        parserForLanguage,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
         ...additionalOptions,
       });
       const application = await parseArchive(archive, '<unknown>', {
@@ -185,6 +201,8 @@ export function scaffold(
           }),
         ),
         Compartment,
+        parserForLanguage,
+        ...additionalOptions,
       });
       const { namespace } = await application.import({
         globals: { ...globals, ...addGlobals },
@@ -209,6 +227,10 @@ export function scaffold(
         conditions: new Set(['development', ...(conditions || [])]),
         searchSuffixes,
         commonDependencies,
+        parserForLanguage,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
         ...additionalOptions,
       });
       const prefixArchive = new Uint8Array(archive.length + 10);
@@ -217,6 +239,8 @@ export function scaffold(
       const application = await parseArchive(prefixArchive, '<unknown>', {
         modules,
         Compartment,
+        parserForLanguage,
+        ...additionalOptions,
       });
       const { namespace } = await application.import({
         globals: { ...globals, ...addGlobals },
@@ -253,11 +277,17 @@ export function scaffold(
         conditions: new Set(['development', ...(conditions || [])]),
         searchSuffixes,
         commonDependencies,
+        parserForLanguage,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
         ...additionalOptions,
       });
       const application = await loadArchive(fakeRead, 'app.agar', {
         modules,
         Compartment,
+        parserForLanguage,
+        ...additionalOptions,
       });
       const { namespace } = await application.import({
         globals: { ...globals, ...addGlobals },
@@ -306,6 +336,10 @@ export function scaffold(
         searchSuffixes,
         commonDependencies,
         sourceMapHook,
+        parserForLanguage,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -314,6 +348,7 @@ export function scaffold(
         modules,
         Compartment,
         computeSourceMapLocation,
+        parserForLanguage,
         ...additionalOptions,
       });
 
@@ -341,6 +376,10 @@ export function scaffold(
         conditions: new Set(['development', ...(conditions || [])]),
         searchSuffixes,
         commonDependencies,
+        parserForLanguage,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -349,6 +388,10 @@ export function scaffold(
         conditions: new Set(['development', ...(conditions || [])]),
         searchSuffixes,
         commonDependencies,
+        parserForLanguage,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -361,6 +404,7 @@ export function scaffold(
           conditions: new Set(['development', ...(conditions || [])]),
           computeSha512,
           expectedSha512,
+          parserForLanguage,
           ...additionalOptions,
         },
       );
@@ -378,6 +422,10 @@ export function scaffold(
         conditions: new Set(['development', ...(conditions || [])]),
         searchSuffixes,
         commonDependencies,
+        parserForLanguage,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -386,6 +434,10 @@ export function scaffold(
         conditions: new Set(['development', ...(conditions || [])]),
         searchSuffixes,
         commonDependencies,
+        parserForLanguage,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -403,6 +455,7 @@ export function scaffold(
           parseArchive(corruptArchive, 'app.agar', {
             computeSha512,
             expectedSha512,
+            parserForLanguage,
             ...additionalOptions,
           }),
         {

From 0147dce70e80995b8d17eaa86e49e82a77b8cd33 Mon Sep 17 00:00:00 2001
From: Kris Kowal <kris@agoric.com>
Date: Sun, 3 Nov 2024 23:21:45 -0800
Subject: [PATCH 2/6] refactor(compartment-mapper): Remove languageForExtension
 from link options

---
 .../compartment-mapper/src/archive-lite.js     |  5 -----
 packages/compartment-mapper/src/bundle.js      |  1 -
 .../compartment-mapper/src/capture-lite.js     |  7 ++-----
 .../src/import-archive-lite.js                 |  8 --------
 packages/compartment-mapper/src/import-lite.js |  6 ------
 packages/compartment-mapper/src/link.js        | 18 ++----------------
 .../compartment-mapper/src/types/external.ts   |  2 --
 .../compartment-mapper/src/types/internal.ts   |  4 +---
 8 files changed, 5 insertions(+), 46 deletions(-)

diff --git a/packages/compartment-mapper/src/archive-lite.js b/packages/compartment-mapper/src/archive-lite.js
index 85f02d48c4..4822bc4170 100644
--- a/packages/compartment-mapper/src/archive-lite.js
+++ b/packages/compartment-mapper/src/archive-lite.js
@@ -322,15 +322,11 @@ const digestFromMap = async (powers, compartmentMap, options = {}) => {
     policy = undefined,
     sourceMapHook = undefined,
     parserForLanguage: parserForLanguageOption = {},
-    languageForExtension: languageForExtensionOption = {},
   } = options;
 
   const parserForLanguage = freeze(
     assign(create(null), parserForLanguageOption),
   );
-  const languageForExtension = freeze(
-    assign(create(null), languageForExtensionOption),
-  );
 
   const { read, computeSha512 } = unpackReadPowers(powers);
 
@@ -365,7 +361,6 @@ const digestFromMap = async (powers, compartmentMap, options = {}) => {
     makeImportHook,
     moduleTransforms,
     parserForLanguage,
-    languageForExtension,
     archiveOnly: true,
   });
   await compartment.load(entryModuleSpecifier);
diff --git a/packages/compartment-mapper/src/bundle.js b/packages/compartment-mapper/src/bundle.js
index 3884db3bb8..068f205433 100644
--- a/packages/compartment-mapper/src/bundle.js
+++ b/packages/compartment-mapper/src/bundle.js
@@ -305,7 +305,6 @@ export const makeBundle = async (readPowers, moduleLocation, options) => {
     makeImportHook,
     moduleTransforms,
     parserForLanguage,
-    languageForExtension,
   });
   await compartment.load(entryModuleSpecifier);
 
diff --git a/packages/compartment-mapper/src/capture-lite.js b/packages/compartment-mapper/src/capture-lite.js
index 9513e9b973..20da5b58b0 100644
--- a/packages/compartment-mapper/src/capture-lite.js
+++ b/packages/compartment-mapper/src/capture-lite.js
@@ -263,22 +263,19 @@ const captureCompartmentMap = (compartmentMap, sources) => {
 export const captureFromMap = async (powers, compartmentMap, options = {}) => {
   const {
     moduleTransforms,
+    syncModuleTransforms,
     modules: exitModules = {},
     searchSuffixes = undefined,
     importHook: exitModuleImportHook = undefined,
     policy = undefined,
     sourceMapHook = undefined,
     parserForLanguage: parserForLanguageOption = {},
-    languageForExtension: languageForExtensionOption = {},
     Compartment = defaultCompartment,
   } = options;
 
   const parserForLanguage = freeze(
     assign(create(null), parserForLanguageOption),
   );
-  const languageForExtension = freeze(
-    assign(create(null), languageForExtensionOption),
-  );
 
   const { read, computeSha512 } = unpackReadPowers(powers);
 
@@ -312,8 +309,8 @@ export const captureFromMap = async (powers, compartmentMap, options = {}) => {
     resolve,
     makeImportHook,
     moduleTransforms,
+    syncModuleTransforms,
     parserForLanguage,
-    languageForExtension,
     archiveOnly: true,
     Compartment,
   });
diff --git a/packages/compartment-mapper/src/import-archive-lite.js b/packages/compartment-mapper/src/import-archive-lite.js
index b05c6b79ac..6f2ff27e94 100644
--- a/packages/compartment-mapper/src/import-archive-lite.js
+++ b/packages/compartment-mapper/src/import-archive-lite.js
@@ -259,15 +259,11 @@ export const parseArchive = async (
     modules = undefined,
     importHook: exitModuleImportHook = undefined,
     parserForLanguage: parserForLanguageOption = {},
-    languageForExtension: languageForExtensionOption = {},
   } = options;
 
   const parserForLanguage = freeze(
     assign(create(null), parserForLanguageOption),
   );
-  const languageForExtension = freeze(
-    assign(create(null), languageForExtensionOption),
-  );
 
   const archive = new ZipReader(archiveBytes, { name: archiveLocation });
 
@@ -343,7 +339,6 @@ export const parseArchive = async (
     const { compartment, pendingJobsPromise } = link(compartmentMap, {
       makeImportHook,
       parserForLanguage,
-      languageForExtension,
       modules: Object.fromEntries(
         Object.keys(modules || {}).map(specifier => {
           return [specifier, { namespace: {} }];
@@ -390,7 +385,6 @@ export const parseArchive = async (
     const { compartment, pendingJobsPromise } = link(compartmentMap, {
       makeImportHook,
       parserForLanguage,
-      languageForExtension,
       globals,
       modules,
       transforms,
@@ -425,7 +419,6 @@ export const loadArchive = async (
     modules,
     computeSourceMapLocation,
     parserForLanguage,
-    languageForExtension,
   } = options;
   const archiveBytes = await read(archiveLocation);
   return parseArchive(archiveBytes, archiveLocation, {
@@ -435,7 +428,6 @@ export const loadArchive = async (
     modules,
     computeSourceMapLocation,
     parserForLanguage,
-    languageForExtension,
   });
 };
 
diff --git a/packages/compartment-mapper/src/import-lite.js b/packages/compartment-mapper/src/import-lite.js
index 39118c5d36..d97ae195a0 100644
--- a/packages/compartment-mapper/src/import-lite.js
+++ b/packages/compartment-mapper/src/import-lite.js
@@ -95,15 +95,11 @@ export const loadFromMap = async (readPowers, compartmentMap, options = {}) => {
   const {
     searchSuffixes = undefined,
     parserForLanguage: parserForLanguageOption = {},
-    languageForExtension: languageForExtensionOption = {},
   } = options;
 
   const parserForLanguage = freeze(
     assign(create(null), parserForLanguageOption),
   );
-  const languageForExtension = freeze(
-    assign(create(null), languageForExtensionOption),
-  );
 
   /**
    * Object containing options and read powers that fulfills all requirements
@@ -199,7 +195,6 @@ export const loadFromMap = async (readPowers, compartmentMap, options = {}) => {
         makeImportHook,
         makeImportNowHook,
         parserForLanguage,
-        languageForExtension,
         globals,
         transforms,
         syncModuleTransforms,
@@ -213,7 +208,6 @@ export const loadFromMap = async (readPowers, compartmentMap, options = {}) => {
       ({ compartment, pendingJobsPromise } = link(compartmentMap, {
         makeImportHook,
         parserForLanguage,
-        languageForExtension,
         globals,
         transforms,
         moduleTransforms,
diff --git a/packages/compartment-mapper/src/link.js b/packages/compartment-mapper/src/link.js
index 42e4c842c5..b2b1414f5d 100644
--- a/packages/compartment-mapper/src/link.js
+++ b/packages/compartment-mapper/src/link.js
@@ -11,15 +11,14 @@
 /**
  * @import {ModuleMapHook} from 'ses'
  * @import {
- *   AsyncParseFn,
  *   CompartmentDescriptor,
  *   CompartmentMapDescriptor,
  *   ImportNowHookMaker,
- *   LanguageForExtension,
  *   LinkOptions,
  *   LinkResult,
  *   ModuleDescriptor,
  *   ParseFn,
+ *   AsyncParseFn,
  *   ParserForLanguage,
  *   ParserImplementation,
  *   ShouldDeferError,
@@ -254,7 +253,6 @@ export const link = (
     makeImportHook,
     makeImportNowHook = impossibleImportNowHookMaker,
     parserForLanguage: parserForLanguageOption = {},
-    languageForExtension: languageForExtensionOption = {},
     globals = {},
     transforms = [],
     moduleTransforms,
@@ -279,10 +277,6 @@ export const link = (
 
   const pendingJobs = [];
 
-  /** @type {LanguageForExtension} */
-  const defaultLanguageForExtension = freeze(
-    assign(create(null), languageForExtensionOption),
-  );
   /** @type {ParserForLanguage} */
   const parserForLanguage = freeze(
     assign(create(null), parserForLanguageOption),
@@ -300,7 +294,7 @@ export const link = (
     const {
       location,
       name,
-      parsers: languageForExtensionOverrides = {},
+      parsers: languageForExtension = {},
       types: languageForModuleSpecifier = {},
     } = compartmentDescriptor;
 
@@ -314,14 +308,6 @@ export const link = (
     // The `moduleMapHook` writes back to the compartment map.
     compartmentDescriptor.modules = modules;
 
-    /** @type {LanguageForExtension} */
-    const languageForExtension = freeze(
-      assign(
-        create(null),
-        defaultLanguageForExtension,
-        languageForExtensionOverrides,
-      ),
-    );
     // TS is kind of dumb about this, so we can use a type assertion to avoid a
     // pointless ternary.
     const parse = /** @type {ParseFn|AsyncParseFn} */ (
diff --git a/packages/compartment-mapper/src/types/external.ts b/packages/compartment-mapper/src/types/external.ts
index 33f261ae5a..b922cb66f7 100644
--- a/packages/compartment-mapper/src/types/external.ts
+++ b/packages/compartment-mapper/src/types/external.ts
@@ -42,7 +42,6 @@ export type ParseArchiveOptions = Partial<{
   ModulesOption &
   CompartmentOption &
   ParserForLanguageOption &
-  LanguageForExtensionOption &
   ExitModuleImportHookOption;
 
 export type LoadArchiveOptions = ParseArchiveOptions;
@@ -204,7 +203,6 @@ type SyncImportingOptions = ModulesOption &
 
 type LinkingOptions = ParserForLanguageOption &
   CompartmentOption &
-  LanguageForExtensionOption &
   SyncModuleTransformsOption &
   ModuleTransformsOption;
 
diff --git a/packages/compartment-mapper/src/types/internal.ts b/packages/compartment-mapper/src/types/internal.ts
index 2fd8c37afe..8cce0cd5f4 100644
--- a/packages/compartment-mapper/src/types/internal.ts
+++ b/packages/compartment-mapper/src/types/internal.ts
@@ -26,7 +26,6 @@ import type {
   CompartmentSources,
   ExecuteOptions,
   ExitModuleImportNowHook,
-  LanguageForExtensionOption,
   ModuleTransforms,
   ParseFn,
   ParserForLanguage,
@@ -45,8 +44,7 @@ export type LinkOptions = {
   moduleTransforms?: ModuleTransforms;
   syncModuleTransforms?: SyncModuleTransforms;
   archiveOnly?: boolean;
-} & ExecuteOptions &
-  LanguageForExtensionOption;
+} & ExecuteOptions;
 
 export type LinkResult = {
   compartment: Compartment;

From eb8a9b725090ca8b591d1c8692166cc9a36b7d9d Mon Sep 17 00:00:00 2001
From: Kris Kowal <kris@agoric.com>
Date: Wed, 6 Nov 2024 16:53:38 -0800
Subject: [PATCH 3/6] doc(compartment-mapper): Language extensions
 documentation

---
 packages/compartment-mapper/README.md | 70 ++++++++++++++++-----------
 1 file changed, 43 insertions(+), 27 deletions(-)

diff --git a/packages/compartment-mapper/README.md b/packages/compartment-mapper/README.md
index 4013b692ec..9481a112d0 100644
--- a/packages/compartment-mapper/README.md
+++ b/packages/compartment-mapper/README.md
@@ -204,6 +204,8 @@ does not exist, to the `index.js` file in the directory with the same name.
 > `fetch` global, in conjunction with usable values for `import.meta.url` in
 > ECMAScript modules or `__dirname` and `__filename` in CommonJS modules.
 
+## Language Extensions
+
 Officially beginning with Node.js 14, Node.js treats `.mjs` files as ECMAScript
 modules and `.cjs` files as CommonJS modules.
 The `.js` extension indicates a CommonJS module by default, to maintain
@@ -211,30 +213,6 @@ backward compatibility.
 However, packages that have a `type` property that explicitly says `module`
 will treat a `.js` file as an ECMAScript module.
 
-This unforunately conflicts with packages written to work with the ECMAScript
-module system emulator in the `esm` package on npm, which allows every file
-with the `js` extension to be an ECMAScript module that presents itself to
-Node.js as a CommonJS module.
-To overcome such obstacles, the compartment mapper will accept a non-standard
-`parsers` property in `package.json` that maps file extensions, specifically
-`js` to the corresponding language name, one of `mjs` for ECMAScript modules,
-`cjs` for CommonJS modules, and `json` for JSON modules.
-All other language names are reserved and the defaults for files with the
-extensions `cjs`, `mjs`, `json`, `text`, and `bytes` default to the language of
-the same name unless overridden.
-JSON modules export a default object resulting from the conventional JSON.parse
-of the module's UTF-8 encoded bytes.
-Text modules export a default string from the module's UTF-8 encoded bytes.
-Bytes modules export a default ArrayBuffer capturing the module's bytes.
-If compartment mapper sees `parsers`, it ignores `type`, so these can
-contradict where using the `esm` emulator requires.
-
-```json
-{
-  "parsers": {"js": "mjs"}
-}
-```
-
 Many Node.js applications using CommonJS modules expect to be able to `require`
 a JSON file like `package.json`.
 The compartment mapper supports loading JSON modules from any type of module.
@@ -252,9 +230,47 @@ As of Node.js 14, Node does not support loading ECMAScript modules from
 CommonJS modules, so using this feature may limit compatibility with the
 Node.js platform.
 
-> TODO A future version may introduce language plugins, so a package may state
-> that files with a particular extension are either parsed or linked with
-> another module.
+The compartment mapper supports language plugins.
+The languages supported by default are:
+
+- `mjs` for ECMAScript modules,
+- `cjs` for CommonJS modules,
+- `json` for JSON modules,
+- `text` for UTF-8 encoded text files,
+- `bytes` for any file, exporting a `Uint8Array` as `default`,
+- `pre-mjs-json` for pre-compiled ECMAScript modules captured as JSON in
+  archives, and
+- `pre-cjs-json` for pre-compiled CommonJS modules captured as JSON in
+  archives.
+
+The compartment mapper accepts extensions to this set of languages with
+the `parserForLanguage` option supported by many functions.
+See `src/types/external.ts` for the type and expected behavior for
+parsers.
+
+These language identifiers are keys for the `moduleTransforms` and
+`syncModuleTransforms` options, which may map each language to a transform
+function.
+The language identifiers are also the values for a `languageForExtension`,
+`moduleLanguageForExtension`, and `commonjsLanguageForExtension` options to
+configure additional extension-to-language mappings for a module and its
+transitive dependencies.
+
+For any package that has `type` set to `"module"` in its `package.json`,
+`moduleLangaugeForExtension` will precede `languageForExtension`.
+Packages with `type` set to `"commonjs"` or simply not set,
+`commonjsLanguageForExtension` will precede `languageForExtension`.
+This provides an hook for mapping TypeScript's `.ts` to either `.cts` or
+`.mts`.
+
+In the scope any given package, the `parsers` property in `package.json` may
+override the extension-to-language mapping.
+
+```json
+{
+  "parsers": { "png": "bytes" }
+}
+```
 
 > TODO
 >

From 3f6d963ec9e3b8728293ddf4a134422a70a58ba5 Mon Sep 17 00:00:00 2001
From: Kris Kowal <kris@agoric.com>
Date: Fri, 8 Nov 2024 14:27:09 -0800
Subject: [PATCH 4/6] test(compartment-mapper): Expand test coverage over lite
 interfaces

---
 .../src/import-archive-lite.js                |  10 +-
 .../compartment-mapper/src/import-lite.js     |   7 +-
 packages/compartment-mapper/test/scaffold.js  | 149 ++++++++++++++++++
 .../test/snapshots/error-handling.test.js.md  |  73 +++++++++
 .../snapshots/error-handling.test.js.snap     | Bin 805 -> 910 bytes
 .../test/snapshots/policy.test.js.md          |  54 +++++++
 .../test/snapshots/policy.test.js.snap        | Bin 782 -> 922 bytes
 7 files changed, 284 insertions(+), 9 deletions(-)

diff --git a/packages/compartment-mapper/src/import-archive-lite.js b/packages/compartment-mapper/src/import-archive-lite.js
index 6f2ff27e94..5c50c41358 100644
--- a/packages/compartment-mapper/src/import-archive-lite.js
+++ b/packages/compartment-mapper/src/import-archive-lite.js
@@ -46,8 +46,6 @@ import { assertCompartmentMap } from './compartment-map.js';
 import { exitModuleImportHookMaker } from './import-hook.js';
 import { attenuateModuleHook, enforceModulePolicy } from './policy.js';
 
-const DefaultCompartment = Compartment;
-
 const { Fail, quote: q } = assert;
 
 const textDecoder = new TextDecoder();
@@ -255,7 +253,7 @@ export const parseArchive = async (
     expectedSha512 = undefined,
     computeSourceLocation = undefined,
     computeSourceMapLocation = undefined,
-    Compartment = DefaultCompartment,
+    Compartment: CompartmentParseOption = Compartment,
     modules = undefined,
     importHook: exitModuleImportHook = undefined,
     parserForLanguage: parserForLanguageOption = {},
@@ -344,7 +342,7 @@ export const parseArchive = async (
           return [specifier, { namespace: {} }];
         }),
       ),
-      Compartment,
+      Compartment: CompartmentParseOption,
     });
 
     await pendingJobsPromise;
@@ -363,7 +361,7 @@ export const parseArchive = async (
       modules,
       transforms,
       __shimTransforms__,
-      Compartment,
+      Compartment: CompartmentOption = CompartmentParseOption,
       importHook: exitModuleImportHook,
     } = options || {};
 
@@ -389,7 +387,7 @@ export const parseArchive = async (
       modules,
       transforms,
       __shimTransforms__,
-      Compartment,
+      Compartment: CompartmentOption,
     });
 
     await pendingJobsPromise;
diff --git a/packages/compartment-mapper/src/import-lite.js b/packages/compartment-mapper/src/import-lite.js
index d97ae195a0..71d748f992 100644
--- a/packages/compartment-mapper/src/import-lite.js
+++ b/packages/compartment-mapper/src/import-lite.js
@@ -95,6 +95,7 @@ export const loadFromMap = async (readPowers, compartmentMap, options = {}) => {
   const {
     searchSuffixes = undefined,
     parserForLanguage: parserForLanguageOption = {},
+    Compartment: LoadCompartmentOption = Compartment,
   } = options;
 
   const parserForLanguage = freeze(
@@ -150,7 +151,7 @@ export const loadFromMap = async (readPowers, compartmentMap, options = {}) => {
       modules,
       transforms,
       __shimTransforms__,
-      Compartment,
+      Compartment: CompartmentOption = LoadCompartmentOption,
       importHook: exitModuleImportHook,
     } = options;
     const compartmentExitModuleImportHook = exitModuleImportHookMaker({
@@ -199,7 +200,7 @@ export const loadFromMap = async (readPowers, compartmentMap, options = {}) => {
         transforms,
         syncModuleTransforms,
         __shimTransforms__,
-        Compartment,
+        Compartment: CompartmentOption,
       }));
     } else {
       // sync module transforms are allowed, because they are "compatible"
@@ -213,7 +214,7 @@ export const loadFromMap = async (readPowers, compartmentMap, options = {}) => {
         moduleTransforms,
         syncModuleTransforms,
         __shimTransforms__,
-        Compartment,
+        Compartment: CompartmentOption,
       }));
     }
 
diff --git a/packages/compartment-mapper/test/scaffold.js b/packages/compartment-mapper/test/scaffold.js
index de99135b02..a150378726 100644
--- a/packages/compartment-mapper/test/scaffold.js
+++ b/packages/compartment-mapper/test/scaffold.js
@@ -13,6 +13,13 @@ import {
   importArchive,
   hashLocation,
 } from '../index.js';
+
+import { mapNodeModules } from '../src/node-modules.js';
+import { loadFromMap, importFromMap } from '../src/import-lite.js';
+import { makeArchiveFromMap } from '../src/archive-lite.js';
+import { defaultParserForLanguage } from '../src/import-parsers.js';
+import { defaultParserForLanguage as defaultArchiveParserForLanguage } from '../src/archive-parsers.js';
+
 import { makeReadPowers } from '../src/node-powers.js';
 
 export const readPowers = makeReadPowers({
@@ -152,6 +159,93 @@ export function scaffold(
     return namespace;
   });
 
+  wrap(test, 'Location')(
+    `${name} / mapNodeModules / importFromMap`,
+    async (t, Compartment) => {
+      t.plan(fixtureAssertionCount);
+      await setup();
+
+      const languages = Object.keys({
+        ...defaultParserForLanguage,
+        ...parserForLanguage,
+      });
+
+      const map = await mapNodeModules(readPowers, fixture, {
+        languages,
+        policy,
+        modules,
+        Compartment,
+        conditions: new Set(['development', ...(conditions || [])]),
+        commonDependencies,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
+        ...additionalOptions,
+      });
+
+      const { namespace } = await importFromMap(readPowers, map, {
+        globals: { ...globals, ...addGlobals },
+        policy,
+        modules,
+        Compartment,
+        searchSuffixes,
+        parserForLanguage: {
+          ...defaultParserForLanguage,
+          ...parserForLanguage,
+        },
+        ...additionalOptions,
+      });
+
+      return namespace;
+    },
+  );
+
+  wrap(test, 'Location')(
+    `${name} / mapNodeModules / loadFromMap / import`,
+    async (t, Compartment) => {
+      t.plan(fixtureAssertionCount);
+      await setup();
+
+      const languages = Object.keys({
+        ...defaultParserForLanguage,
+        ...parserForLanguage,
+      });
+
+      const map = await mapNodeModules(readPowers, fixture, {
+        languages,
+        policy,
+        modules,
+        Compartment,
+        conditions: new Set(['development', ...(conditions || [])]),
+        commonDependencies,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
+        ...additionalOptions,
+      });
+
+      const app = await loadFromMap(readPowers, map, {
+        policy,
+        Compartment,
+        searchSuffixes,
+        parserForLanguage: {
+          ...defaultParserForLanguage,
+          ...parserForLanguage,
+        },
+        ...additionalOptions,
+      });
+
+      const { namespace } = await app.import({
+        globals: { ...globals, ...addGlobals },
+        modules,
+        Compartment,
+        ...additionalOptions,
+      });
+
+      return namespace;
+    },
+  );
+
   wrap(test, 'Location')(`${name} / importLocation`, async (t, Compartment) => {
     t.plan(fixtureAssertionCount);
     await setup();
@@ -365,6 +459,61 @@ export function scaffold(
     },
   );
 
+  wrap(test, 'Archive')(
+    `${name} / mapNodeModules / makeArchiveFromMap / importArchive`,
+    async (t, Compartment) => {
+      t.plan(fixtureAssertionCount);
+      await setup();
+
+      const languages = Object.keys({
+        ...defaultArchiveParserForLanguage,
+        ...parserForLanguage,
+      });
+
+      const map = await mapNodeModules(readPowers, fixture, {
+        policy,
+        conditions: new Set(['development', ...(conditions || [])]),
+        commonDependencies,
+        languages,
+        languageForExtension,
+        commonjsLanguageForExtension,
+        moduleLanguageForExtension,
+        ...additionalOptions,
+      });
+
+      const archive = await makeArchiveFromMap(readPowers, map, {
+        modules,
+        policy,
+        searchSuffixes,
+        parserForLanguage: {
+          ...defaultArchiveParserForLanguage,
+          ...parserForLanguage,
+        },
+        ...additionalOptions,
+      });
+      const application = await parseArchive(archive, '<unknown>', {
+        modules: Object.fromEntries(
+          Object.keys(modules).map((specifier, index) => {
+            // Replacing the namespace with an arbitrary index ensures that the
+            // parse phase does not depend on the type or values of the exit module
+            // set.
+            return [specifier, index];
+          }),
+        ),
+        Compartment,
+        parserForLanguage,
+        ...additionalOptions,
+      });
+      const { namespace } = await application.import({
+        globals: { ...globals, ...addGlobals },
+        modules,
+        Compartment,
+        ...additionalOptions,
+      });
+      return namespace;
+    },
+  );
+
   if (!onError) {
     test(`${name} / makeArchive / parseArchive / hashArchive consistency`, async (t, Compartment) => {
       t.plan(1);
diff --git a/packages/compartment-mapper/test/snapshots/error-handling.test.js.md b/packages/compartment-mapper/test/snapshots/error-handling.test.js.md
index be0ed22671..efd4c6c1e4 100644
--- a/packages/compartment-mapper/test/snapshots/error-handling.test.js.md
+++ b/packages/compartment-mapper/test/snapshots/error-handling.test.js.md
@@ -6,6 +6,26 @@ Generated by [AVA](https://avajs.dev).
 
 ## fixtures-error-handling / esm / loadLocation
 
+> Snapshot 1
+
+    `TypeError: Failed to load module "./main.js" in package "file://.../compartment-mapper/test/fixtures-error-handling/node_modules/esm/" (1 underlying failures: Cannot find external module "missing" in package file://.../compartment-mapper/test/fixtures-error-handling/node_modules/esm/␊
+        at throwAggregateError (file://.../ses/src/module-load.js:…)␊
+        at load (file://.../ses/src/module-load.js:…)␊
+        at async file://.../compartment-mapper/test/scaffold.js:…␊
+        at async file://.../compartment-mapper/test/scaffold.js:…`
+
+## fixtures-error-handling / esm / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    `TypeError: Failed to load module "./main.js" in package "file://.../compartment-mapper/test/fixtures-error-handling/node_modules/esm/" (1 underlying failures: Cannot find external module "missing" in package file://.../compartment-mapper/test/fixtures-error-handling/node_modules/esm/␊
+        at throwAggregateError (file://.../ses/src/module-load.js:…)␊
+        at load (file://.../ses/src/module-load.js:…)␊
+        at async file://.../compartment-mapper/test/scaffold.js:…␊
+        at async file://.../compartment-mapper/test/scaffold.js:…`
+
+## fixtures-error-handling / esm / mapNodeModules / loadFromMap / import
+
 > Snapshot 1
 
     `TypeError: Failed to load module "./main.js" in package "file://.../compartment-mapper/test/fixtures-error-handling/node_modules/esm/" (1 underlying failures: Cannot find external module "missing" in package file://.../compartment-mapper/test/fixtures-error-handling/node_modules/esm/␊
@@ -78,8 +98,45 @@ Generated by [AVA](https://avajs.dev).
         at async file://.../compartment-mapper/test/scaffold.js:…␊
         at async file://.../compartment-mapper/test/scaffold.js:…`
 
+## fixtures-error-handling / esm / mapNodeModules / makeArchiveFromMap / importArchive
+
+> Snapshot 1
+
+    `TypeError: Failed to load module "./main.js" in package "file://.../compartment-mapper/test/fixtures-error-handling/node_modules/esm/" (1 underlying failures: Cannot find external module "missing" in package file://.../compartment-mapper/test/fixtures-error-handling/node_modules/esm/␊
+        at throwAggregateError (file://.../ses/src/module-load.js:…)␊
+        at load (file://.../ses/src/module-load.js:…)␊
+        at async digestFromMap (file://.../compartment-mapper/src/archive-lite.js:…)␊
+        at async makeAndHashArchiveFromMap (file://.../compartment-mapper/src/archive-lite.js:…)␊
+        at async makeArchiveFromMap (file://.../compartment-mapper/src/archive-lite.js:…)␊
+        at async file://.../compartment-mapper/test/scaffold.js:…␊
+        at async file://.../compartment-mapper/test/scaffold.js:…`
+
 ## fixtures-error-handling / cjs / loadLocation
 
+> Snapshot 1
+
+    `Error: Cannot find external module "missing" in package file://.../compartment-mapper/test/fixtures-error-handling/node_modules/cjs/␊
+        at importHook (file://.../compartment-mapper/src/import-hook.js:…)␊
+        at async asyncTrampoline (file://.../ses/src/module-load.js:…)␊
+        at async drainQueue (file://.../ses/src/module-load.js:…)␊
+        at async load (file://.../ses/src/module-load.js:…)␊
+        at async file://.../compartment-mapper/test/scaffold.js:…␊
+        at async file://.../compartment-mapper/test/scaffold.js:…`
+
+## fixtures-error-handling / cjs / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    `Error: Cannot find external module "missing" in package file://.../compartment-mapper/test/fixtures-error-handling/node_modules/cjs/␊
+        at importHook (file://.../compartment-mapper/src/import-hook.js:…)␊
+        at async asyncTrampoline (file://.../ses/src/module-load.js:…)␊
+        at async drainQueue (file://.../ses/src/module-load.js:…)␊
+        at async load (file://.../ses/src/module-load.js:…)␊
+        at async file://.../compartment-mapper/test/scaffold.js:…␊
+        at async file://.../compartment-mapper/test/scaffold.js:…`
+
+## fixtures-error-handling / cjs / mapNodeModules / loadFromMap / import
+
 > Snapshot 1
 
     `Error: Cannot find external module "missing" in package file://.../compartment-mapper/test/fixtures-error-handling/node_modules/cjs/␊
@@ -165,3 +222,19 @@ Generated by [AVA](https://avajs.dev).
         at execute (file://.../ses/src/module-instance.js:…)␊
         at compartmentImportNow (file://.../ses/src/compartment.js:…)␊
         at file://.../ses/src/compartment.js:…`
+
+## fixtures-error-handling / cjs / mapNodeModules / makeArchiveFromMap / importArchive
+
+> Snapshot 1
+
+    `Error: Cannot find external module "missing" in package file://.../compartment-mapper/test/fixtures-error-handling/node_modules/cjs/␊
+        at Object.execute (file://.../compartment-mapper/src/import-archive-lite.js:…)␊
+        at execute (file://.../ses/src/module-instance.js:…)␊
+        at compartmentImportNow (file://.../ses/src/compartment.js:…)␊
+        at Compartment.importNow (file://.../ses/src/compartment.js:…)␊
+        at require (file://.../compartment-mapper/src/parse-cjs-shared-export-wrapper.js:…)␊
+        at Proxy.eval (eval at <anonymous> (eval at makeEvaluate (file://.../ses/src/make-evaluate.js:…)), <anonymous>:…)␊
+        at Object.execute (file://.../compartment-mapper/src/parse-pre-cjs.js:…)␊
+        at execute (file://.../ses/src/module-instance.js:…)␊
+        at compartmentImportNow (file://.../ses/src/compartment.js:…)␊
+        at file://.../ses/src/compartment.js:…`
diff --git a/packages/compartment-mapper/test/snapshots/error-handling.test.js.snap b/packages/compartment-mapper/test/snapshots/error-handling.test.js.snap
index d5b62f73817fe30af18fff6e065f7baa7a8f0d14..dd06112fd364d1c34ff44addabb513d236af6c58 100644
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diff --git a/packages/compartment-mapper/test/snapshots/policy.test.js.md b/packages/compartment-mapper/test/snapshots/policy.test.js.md
index a74af4324b..54570ac6ad 100644
--- a/packages/compartment-mapper/test/snapshots/policy.test.js.md
+++ b/packages/compartment-mapper/test/snapshots/policy.test.js.md
@@ -6,6 +6,18 @@ Generated by [AVA](https://avajs.dev).
 
 ## policy - attack - browser alias - with alias hint / loadLocation
 
+> Snapshot 1
+
+    'Failed to load module "./attack.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (1 underlying failures: Importing "dan" in "eve-v1.0.0" was not allowed by packages policy {"dan":true} (info: Blocked in linking. "dan" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/hackity/".)'
+
+## policy - attack - browser alias - with alias hint / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    'Failed to load module "./attack.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (1 underlying failures: Importing "dan" in "eve-v1.0.0" was not allowed by packages policy {"dan":true} (info: Blocked in linking. "dan" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/hackity/".)'
+
+## policy - attack - browser alias - with alias hint / mapNodeModules / loadFromMap / import
+
 > Snapshot 1
 
     'Failed to load module "./attack.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (1 underlying failures: Importing "dan" in "eve-v1.0.0" was not allowed by packages policy {"dan":true} (info: Blocked in linking. "dan" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/hackity/".)'
@@ -36,12 +48,30 @@ Generated by [AVA](https://avajs.dev).
 
 ## policy - attack - browser alias - with alias hint / writeArchive / importArchive
 
+> Snapshot 1
+
+    'Failed to load module "./attack.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (1 underlying failures: Importing "dan" in "eve-v1.0.0" was not allowed by packages policy {"dan":true} (info: Blocked in linking. "dan" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/hackity/".)'
+
+## policy - attack - browser alias - with alias hint / mapNodeModules / makeArchiveFromMap / importArchive
+
 > Snapshot 1
 
     'Failed to load module "./attack.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (1 underlying failures: Importing "dan" in "eve-v1.0.0" was not allowed by packages policy {"dan":true} (info: Blocked in linking. "dan" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/hackity/".)'
 
 ## policy - disallowed package with error hint / loadLocation
 
+> Snapshot 1
+
+    'Failed to load module "./index.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (2 underlying failures: Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".), Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".)'
+
+## policy - disallowed package with error hint / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    'Failed to load module "./index.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (2 underlying failures: Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".), Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".)'
+
+## policy - disallowed package with error hint / mapNodeModules / loadFromMap / import
+
 > Snapshot 1
 
     'Failed to load module "./index.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (2 underlying failures: Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".), Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".)'
@@ -72,12 +102,30 @@ Generated by [AVA](https://avajs.dev).
 
 ## policy - disallowed package with error hint / writeArchive / importArchive
 
+> Snapshot 1
+
+    'Failed to load module "./index.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (2 underlying failures: Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".), Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".)'
+
+## policy - disallowed package with error hint / mapNodeModules / makeArchiveFromMap / importArchive
+
 > Snapshot 1
 
     'Failed to load module "./index.js" in package "file://.../compartment-mapper/test/fixtures-policy/node_modules/app/" (2 underlying failures: Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".), Importing "carol" in "alice-v1.0.0" was not allowed by packages policy {"alice>carol":false} (info: Blocked in linking. "carol" is part of the compartment map and resolves to "file://.../compartment-mapper/test/fixtures-policy/node_modules/alice/node_modules/carol/".)'
 
 ## policy - attenuator error aggregation / loadLocation
 
+> Snapshot 1
+
+    'Globals attenuation errors: Error while attenuating globals for "alice" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "carol" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "app" with "myattenuator": "I attenuate, I throw."'
+
+## policy - attenuator error aggregation / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    'Globals attenuation errors: Error while attenuating globals for "alice" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "carol" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "app" with "myattenuator": "I attenuate, I throw."'
+
+## policy - attenuator error aggregation / mapNodeModules / loadFromMap / import
+
 > Snapshot 1
 
     'Globals attenuation errors: Error while attenuating globals for "alice" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "carol" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "app" with "myattenuator": "I attenuate, I throw."'
@@ -111,3 +159,9 @@ Generated by [AVA](https://avajs.dev).
 > Snapshot 1
 
     'Globals attenuation errors: Error while attenuating globals for "alice" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "app" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "carol" with "myattenuator": "I attenuate, I throw."'
+
+## policy - attenuator error aggregation / mapNodeModules / makeArchiveFromMap / importArchive
+
+> Snapshot 1
+
+    'Globals attenuation errors: Error while attenuating globals for "alice" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "app" with "myattenuator": "I attenuate, I throw.", Error while attenuating globals for "carol" with "myattenuator": "I attenuate, I throw."'
diff --git a/packages/compartment-mapper/test/snapshots/policy.test.js.snap b/packages/compartment-mapper/test/snapshots/policy.test.js.snap
index a541d7c80026bb1fac4986c2cce956356d14265b..40cd9b14eaa23cb315dffd95b6b9f4f784a483f7 100644
GIT binary patch
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From fdde110ae975ac43bb618de53a3db60d71a23a8a Mon Sep 17 00:00:00 2001
From: Kris Kowal <kris@agoric.com>
Date: Fri, 8 Nov 2024 15:45:15 -0800
Subject: [PATCH 5/6] docs(compartment-mapper): Workspace
 language-for-extension options

---
 packages/compartment-mapper/NEWS.md   | 6 ++++++
 packages/compartment-mapper/README.md | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/packages/compartment-mapper/NEWS.md b/packages/compartment-mapper/NEWS.md
index 8d37eb98e0..085ebe73ff 100644
--- a/packages/compartment-mapper/NEWS.md
+++ b/packages/compartment-mapper/NEWS.md
@@ -9,6 +9,12 @@ User-visible changes to `@endo/compartment-mapper`:
   package’s `type` in the way we already vary `js` between `cjs` and `mjs`.
   These options enter through the high level functions including `makeArchive`
   and `importLocation`.
+- The new options `workspaceLanguageForExtension`,
+  `workspaceModuleLanguageForExtension`, and
+  `workspaceCommonjsLanguageForExtension` apply like the above except more
+  specifically and for packages that are not physically located under a
+  `node_modules` directory, indicating that JavaScript has not yet been
+  generated from any non-JavaScript source files.
 - Omits unused module descriptors from `compartment-map.json` in archived
   applications, potentially reducing file sizes.
 - Fixes an issue where errors thrown from exit module hooks (`importHook`) would
diff --git a/packages/compartment-mapper/README.md b/packages/compartment-mapper/README.md
index 9481a112d0..6cfbdfb6b9 100644
--- a/packages/compartment-mapper/README.md
+++ b/packages/compartment-mapper/README.md
@@ -263,6 +263,13 @@ Packages with `type` set to `"commonjs"` or simply not set,
 This provides an hook for mapping TypeScript's `.ts` to either `.cts` or
 `.mts`.
 
+The analogous `workspaceLanguageForExtension`,
+`workspaceCommonjsLanguageForExtension`, and
+`workspaceModuleLanguageForExtension` options apply more specifically for
+packages that are not under a `node_modules` directory, indicating that they
+are in the set of linked workspaces and have not been built or published to
+npm.
+
 In the scope any given package, the `parsers` property in `package.json` may
 override the extension-to-language mapping.
 

From 389de7b6f9ff4b191f17c442199c289f12c5b855 Mon Sep 17 00:00:00 2001
From: Kris Kowal <kris@agoric.com>
Date: Fri, 8 Nov 2024 15:46:19 -0800
Subject: [PATCH 6/6] feat(compartment-mapper): Workspace
 language-for-extension options

---
 packages/compartment-mapper/src/archive.js    |  24 ++
 packages/compartment-mapper/src/bundle.js     |  23 ++
 packages/compartment-mapper/src/import.js     |   6 +
 .../compartment-mapper/src/node-modules.js    |  44 ++-
 .../compartment-mapper/src/types/external.ts  |  16 +-
 .../packages/commonjs-app/module.xsonp        |   1 +
 .../packages/commonjs-app/package.json        |   7 +
 .../packages/module-app/module.xsonp          |   1 +
 .../packages/module-app/package.json          |   7 +
 .../packages/parsers-app/module.xsonp         |   1 +
 .../packages/parsers-app/package.json         |   9 +
 .../test/language-for-extension.test.js       | 248 ++++++++++---
 .../test/missing-entry.test.js                |   8 +-
 packages/compartment-mapper/test/scaffold.js  |  42 +++
 .../language-for-extension.test.js.md         | 329 ++++++++++++++++++
 .../language-for-extension.test.js.snap       | Bin 0 -> 1110 bytes
 16 files changed, 709 insertions(+), 57 deletions(-)
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/packages/commonjs-app/module.xsonp
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/packages/commonjs-app/package.json
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/packages/module-app/module.xsonp
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/packages/module-app/package.json
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/packages/parsers-app/module.xsonp
 create mode 100644 packages/compartment-mapper/test/fixtures-language-for-extension/packages/parsers-app/package.json
 create mode 100644 packages/compartment-mapper/test/snapshots/language-for-extension.test.js.md
 create mode 100644 packages/compartment-mapper/test/snapshots/language-for-extension.test.js.snap

diff --git a/packages/compartment-mapper/src/archive.js b/packages/compartment-mapper/src/archive.js
index 992449b25f..b9b4af7837 100644
--- a/packages/compartment-mapper/src/archive.js
+++ b/packages/compartment-mapper/src/archive.js
@@ -90,6 +90,9 @@ export const makeArchive = async (powers, moduleLocation, options = {}) => {
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
     parserForLanguage,
     languages,
     ...otherOptions
@@ -102,6 +105,9 @@ export const makeArchive = async (powers, moduleLocation, options = {}) => {
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
     languages,
   });
 
@@ -130,6 +136,9 @@ export const mapLocation = async (powers, moduleLocation, options = {}) => {
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
     ...otherOptions
   } = assignParserForLanguage(options);
 
@@ -142,6 +151,9 @@ export const mapLocation = async (powers, moduleLocation, options = {}) => {
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
   });
 
   return mapFromMap(powers, compartmentMap, {
@@ -169,6 +181,9 @@ export const hashLocation = async (powers, moduleLocation, options = {}) => {
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
     ...otherOptions
   } = assignParserForLanguage(options);
 
@@ -181,6 +196,9 @@ export const hashLocation = async (powers, moduleLocation, options = {}) => {
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
   });
 
   return hashFromMap(powers, compartmentMap, {
@@ -215,6 +233,9 @@ export const writeArchive = async (
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
     ...otherOptions
   } = assignParserForLanguage(options);
   const compartmentMap = await mapNodeModules(readPowers, moduleLocation, {
@@ -225,6 +246,9 @@ export const writeArchive = async (
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
     languages,
   });
   return writeArchiveFromMap(
diff --git a/packages/compartment-mapper/src/bundle.js b/packages/compartment-mapper/src/bundle.js
index 068f205433..fe63135f1b 100644
--- a/packages/compartment-mapper/src/bundle.js
+++ b/packages/compartment-mapper/src/bundle.js
@@ -237,6 +237,11 @@ export const makeBundle = async (readPowers, moduleLocation, options) => {
     languageForExtension: languageForExtensionOption = {},
     commonjsLanguageForExtension: commonjsLanguageForExtensionOption = {},
     moduleLanguageForExtension: moduleLanguageForExtensionOption = {},
+    workspaceLanguageForExtension: workspaceLanguageForExtensionOption = {},
+    workspaceCommonjsLanguageForExtension:
+      workspaceCommonjsLanguageForExtensionOption = {},
+    workspaceModuleLanguageForExtension:
+      workspaceModuleLanguageForExtensionOption = {},
   } = options || {};
   const conditions = new Set(conditionsOption);
 
@@ -256,6 +261,21 @@ export const makeBundle = async (readPowers, moduleLocation, options) => {
   const moduleLanguageForExtension = Object.freeze(
     Object.assign(Object.create(null), moduleLanguageForExtensionOption),
   );
+  const workspaceLanguageForExtension = Object.freeze(
+    Object.assign(Object.create(null), workspaceLanguageForExtensionOption),
+  );
+  const workspaceCommonjsLanguageForExtension = Object.freeze(
+    Object.assign(
+      Object.create(null),
+      workspaceCommonjsLanguageForExtensionOption,
+    ),
+  );
+  const workspaceModuleLanguageForExtension = Object.freeze(
+    Object.assign(
+      Object.create(null),
+      workspaceModuleLanguageForExtensionOption,
+    ),
+  );
 
   const {
     packageLocation,
@@ -280,6 +300,9 @@ export const makeBundle = async (readPowers, moduleLocation, options) => {
       languageForExtension,
       commonjsLanguageForExtension,
       moduleLanguageForExtension,
+      workspaceLanguageForExtension,
+      workspaceCommonjsLanguageForExtension,
+      workspaceModuleLanguageForExtension,
     },
   );
 
diff --git a/packages/compartment-mapper/src/import.js b/packages/compartment-mapper/src/import.js
index faf7c48bc3..1c6c3cedef 100644
--- a/packages/compartment-mapper/src/import.js
+++ b/packages/compartment-mapper/src/import.js
@@ -83,6 +83,9 @@ export const loadLocation = async (
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
     ...otherOptions
   } = assignParserForLanguage(options);
   // conditions are not present in SyncArchiveOptions
@@ -96,6 +99,9 @@ export const loadLocation = async (
     languageForExtension,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
     languages,
   });
   return loadFromMap(readPowers, compartmentMap, {
diff --git a/packages/compartment-mapper/src/node-modules.js b/packages/compartment-mapper/src/node-modules.js
index f8754c681c..a3f41ace75 100644
--- a/packages/compartment-mapper/src/node-modules.js
+++ b/packages/compartment-mapper/src/node-modules.js
@@ -61,6 +61,8 @@
  * @typedef {object} LanguageOptions
  * @property {LanguageForExtension} commonjsLanguageForExtension
  * @property {LanguageForExtension} moduleLanguageForExtension
+ * @property {LanguageForExtension} workspaceCommonjsLanguageForExtension
+ * @property {LanguageForExtension} workspaceModuleLanguageForExtension
  * @property {Set<string>} languages
  */
 
@@ -217,12 +219,22 @@ const defaultModuleLanguageForExtension = /** @type {const} */ ({
  * @returns {Record<string, string>}
  */
 const inferParsers = (descriptor, location, languageOptions) => {
+  let { moduleLanguageForExtension, commonjsLanguageForExtension } =
+    languageOptions;
   const {
     languages,
-    moduleLanguageForExtension,
-    commonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
   } = languageOptions;
 
+  // Select languageForExtension options based on whether they are physically
+  // under node_modules, indicating that they have not been built for npm,
+  // so any languages that compile to JavaScript may need additional parsers.
+  if (!location.includes('/node_modules/')) {
+    moduleLanguageForExtension = workspaceModuleLanguageForExtension;
+    commonjsLanguageForExtension = workspaceCommonjsLanguageForExtension;
+  }
+
   const {
     type,
     module,
@@ -771,6 +783,9 @@ const translateGraph = (
  *   'languageForExtension' |
  *   'moduleLanguageForExtension' |
  *   'commonjsLanguageForExtension' |
+ *   'workspaceLanguageForExtension' |
+ *   'workspaceModuleLanguageForExtension' |
+ *   'workspaceCommonjsLanguageForExtension' |
  *   'languages'
  * >} options
  */
@@ -778,6 +793,11 @@ const makeLanguageOptions = ({
   languageForExtension: additionalLanguageForExtension = {},
   moduleLanguageForExtension: additionalModuleLanguageForExtension = {},
   commonjsLanguageForExtension: additionalCommonjsLanguageForExtension = {},
+  workspaceLanguageForExtension: additionalWorkspaceLanguageForExtension = {},
+  workspaceModuleLanguageForExtension:
+    additionalWorkspaceModuleLanguageForExtension = {},
+  workspaceCommonjsLanguageForExtension:
+    additionalWorkspaceCommonjsLanguageForExtension = {},
   languages: additionalLanguages = [],
 }) => {
   const commonjsLanguageForExtension = {
@@ -792,10 +812,28 @@ const makeLanguageOptions = ({
     ...defaultModuleLanguageForExtension,
     ...additionalModuleLanguageForExtension,
   };
+  const workspaceCommonjsLanguageForExtension = {
+    ...defaultLanguageForExtension,
+    ...additionalLanguageForExtension,
+    ...defaultCommonjsLanguageForExtension,
+    ...additionalCommonjsLanguageForExtension,
+    ...additionalWorkspaceLanguageForExtension,
+    ...additionalWorkspaceCommonjsLanguageForExtension,
+  };
+  const workspaceModuleLanguageForExtension = {
+    ...defaultLanguageForExtension,
+    ...additionalLanguageForExtension,
+    ...defaultModuleLanguageForExtension,
+    ...additionalModuleLanguageForExtension,
+    ...additionalWorkspaceLanguageForExtension,
+    ...additionalWorkspaceModuleLanguageForExtension,
+  };
 
   const languages = new Set([
     ...Object.values(moduleLanguageForExtension),
     ...Object.values(commonjsLanguageForExtension),
+    ...Object.values(workspaceModuleLanguageForExtension),
+    ...Object.values(workspaceCommonjsLanguageForExtension),
     ...additionalLanguages,
   ]);
 
@@ -803,6 +841,8 @@ const makeLanguageOptions = ({
     languages,
     commonjsLanguageForExtension,
     moduleLanguageForExtension,
+    workspaceCommonjsLanguageForExtension,
+    workspaceModuleLanguageForExtension,
   };
 };
 
diff --git a/packages/compartment-mapper/src/types/external.ts b/packages/compartment-mapper/src/types/external.ts
index b922cb66f7..d0de4e9916 100644
--- a/packages/compartment-mapper/src/types/external.ts
+++ b/packages/compartment-mapper/src/types/external.ts
@@ -71,10 +71,22 @@ type MapNodeModulesOptionsOmitPolicy = Partial<{
   commonDependencies: Record<string, string>;
   /** Maps extensions to languages for all packages, like `txt` to `text` */
   languageForExtension: LanguageForExtension;
-  /** Maps extensions to languages for all type=module packages */
+  /** Maps additional extensions to languages for all type=module packages */
   moduleLanguageForExtension: LanguageForExtension;
-  /** Maps extensions to languages for all type=commonjs packages (default) */
+  /** Maps additional extensions to languages for all type=commonjs packages (default) */
   commonjsLanguageForExtension: LanguageForExtension;
+  /** Maps extensions to languages for packages not under node_modules */
+  workspaceLanguageForExtension: LanguageForExtension;
+  /**
+   * Maps additional extensions to languages for all type=module packages that
+   * are not under node_modules
+   */
+  workspaceModuleLanguageForExtension: LanguageForExtension;
+  /**
+   * Maps additional extensions to languages for all type=commonjs packages
+   * (default)
+   */
+  workspaceCommonjsLanguageForExtension: LanguageForExtension;
   /**
    * Accounts for languages not present as values in any of the extension to
    * language mappings.
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/packages/commonjs-app/module.xsonp b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/commonjs-app/module.xsonp
new file mode 100644
index 0000000000..f1dad2cdf6
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/commonjs-app/module.xsonp
@@ -0,0 +1 @@
+exports({ meaning: 42 });
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/packages/commonjs-app/package.json b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/commonjs-app/package.json
new file mode 100644
index 0000000000..cec862f1c0
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/commonjs-app/package.json
@@ -0,0 +1,7 @@
+{
+  "name": "app",
+  "type": "commonjs",
+  "scripts": {
+    "preinstall": "echo DO NOT INSTALL TEST FIXTURES; exit -1"
+  }
+}
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/packages/module-app/module.xsonp b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/module-app/module.xsonp
new file mode 100644
index 0000000000..f1dad2cdf6
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/module-app/module.xsonp
@@ -0,0 +1 @@
+exports({ meaning: 42 });
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/packages/module-app/package.json b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/module-app/package.json
new file mode 100644
index 0000000000..68d335f7bd
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/module-app/package.json
@@ -0,0 +1,7 @@
+{
+  "name": "app",
+  "type": "module",
+  "scripts": {
+    "preinstall": "echo DO NOT INSTALL TEST FIXTURES; exit -1"
+  }
+}
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/packages/parsers-app/module.xsonp b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/parsers-app/module.xsonp
new file mode 100644
index 0000000000..f1dad2cdf6
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/parsers-app/module.xsonp
@@ -0,0 +1 @@
+exports({ meaning: 42 });
diff --git a/packages/compartment-mapper/test/fixtures-language-for-extension/packages/parsers-app/package.json b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/parsers-app/package.json
new file mode 100644
index 0000000000..8004f6bd58
--- /dev/null
+++ b/packages/compartment-mapper/test/fixtures-language-for-extension/packages/parsers-app/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "app",
+  "parsers": {
+    "xsonp": "jsonp"
+  },
+  "scripts": {
+    "preinstall": "echo DO NOT INSTALL TEST FIXTURES; exit -1"
+  }
+}
diff --git a/packages/compartment-mapper/test/language-for-extension.test.js b/packages/compartment-mapper/test/language-for-extension.test.js
index 591cae76d3..6e6d3ae4c6 100644
--- a/packages/compartment-mapper/test/language-for-extension.test.js
+++ b/packages/compartment-mapper/test/language-for-extension.test.js
@@ -1,6 +1,6 @@
 import 'ses';
 import test from 'ava';
-import { scaffold } from './scaffold.js';
+import { scaffold, sanitizePaths } from './scaffold.js';
 import jsonp from './_parse-jsonp.js';
 
 // The JSONP parser uses harden, as a bit.
@@ -9,6 +9,22 @@ lockdown({
   errorTrapping: 'none',
 });
 
+const meaningfulModule = {
+  default: {
+    meaning: 42,
+  },
+  __proto__: {
+    __proto__: null,
+    [Symbol.toStringTag]: 'Module',
+  },
+};
+
+const assertions = (t, { namespace }) => {
+  t.deepEqual(namespace, meaningfulModule);
+};
+
+const assertionCount = 1;
+
 scaffold(
   'languageForExtension',
   test,
@@ -16,18 +32,8 @@ scaffold(
     'fixtures-language-for-extension/node_modules/module-app/module.xsonp',
     import.meta.url,
   ).href,
-  (t, { namespace }) => {
-    t.deepEqual(namespace, {
-      default: {
-        meaning: 42,
-      },
-      __proto__: {
-        __proto__: null,
-        [Symbol.toStringTag]: 'Module',
-      },
-    });
-  },
-  1,
+  assertions,
+  assertionCount,
   {
     parserForLanguage: { jsonp },
     languageForExtension: { xsonp: 'jsonp' },
@@ -41,21 +47,30 @@ scaffold(
     'fixtures-language-for-extension/node_modules/module-app/module.xsonp',
     import.meta.url,
   ).href,
-  (t, { namespace }) => {
-    t.deepEqual(namespace, {
-      default: {
-        meaning: 42,
-      },
-      __proto__: {
-        __proto__: null,
-        [Symbol.toStringTag]: 'Module',
-      },
-    });
-  },
-  1,
+  assertions,
+  assertionCount,
+  {
+    parserForLanguage: { jsonp },
+    moduleLanguageForExtension: { xsonp: 'jsonp' },
+  },
+);
+
+scaffold(
+  'moduleLanguageForExtension should not be available in commonjs package',
+  test,
+  new URL(
+    'fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  1, // expected number of assertions
   {
     parserForLanguage: { jsonp },
     moduleLanguageForExtension: { xsonp: 'jsonp' },
+    shouldFailBeforeArchiveOperations: true,
+    onError(t, { error }) {
+      t.snapshot(sanitizePaths(error.message));
+    },
   },
 );
 
@@ -66,21 +81,30 @@ scaffold(
     'fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp',
     import.meta.url,
   ).href,
-  (t, { namespace }) => {
-    t.deepEqual(namespace, {
-      default: {
-        meaning: 42,
-      },
-      __proto__: {
-        __proto__: null,
-        [Symbol.toStringTag]: 'Module',
-      },
-    });
-  },
-  1,
+  assertions,
+  assertionCount,
+  {
+    parserForLanguage: { jsonp },
+    commonjsLanguageForExtension: { xsonp: 'jsonp' },
+  },
+);
+
+scaffold(
+  'commonjsLanguageForExtension should not be available in module package',
+  test,
+  new URL(
+    'fixtures-language-for-extension/node_modules/module-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  1, // expected number of assertions
   {
     parserForLanguage: { jsonp },
     commonjsLanguageForExtension: { xsonp: 'jsonp' },
+    shouldFailBeforeArchiveOperations: true,
+    onError(t, { error }) {
+      t.snapshot(sanitizePaths(error.message));
+    },
   },
 );
 
@@ -91,20 +115,146 @@ scaffold(
     'fixtures-language-for-extension/node_modules/parsers-app/module.xsonp',
     import.meta.url,
   ).href,
-  (t, { namespace }) => {
-    t.deepEqual(namespace, {
-      default: {
-        meaning: 42,
-      },
-      __proto__: {
-        __proto__: null,
-        [Symbol.toStringTag]: 'Module',
-      },
-    });
-  },
-  1,
+  assertions,
+  assertionCount,
   {
     parserForLanguage: { jsonp },
     languageForExtension: { xsonp: 'text' },
   },
 );
+
+scaffold(
+  'workspaceLanguageForExtension',
+  test,
+  new URL(
+    'fixtures-language-for-extension/packages/module-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  assertionCount,
+  {
+    parserForLanguage: { jsonp },
+    workspaceLanguageForExtension: { xsonp: 'jsonp' },
+  },
+);
+
+scaffold(
+  'workspaceModuleLanguageForExtension',
+  test,
+  new URL(
+    'fixtures-language-for-extension/packages/module-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  assertionCount,
+  {
+    parserForLanguage: { jsonp },
+    workspaceModuleLanguageForExtension: { xsonp: 'jsonp' },
+  },
+);
+
+scaffold(
+  'workspaceModuleLanguageForExtension should not be available in commonjs package',
+  test,
+  new URL(
+    'fixtures-language-for-extension/package/commonjs-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  1, // expected number of assertions
+  {
+    parserForLanguage: { jsonp },
+    workspaceModuleLanguageForExtension: { xsonp: 'jsonp' },
+    shouldFailBeforeArchiveOperations: true,
+    onError(t, { error }) {
+      t.snapshot(sanitizePaths(error.message));
+    },
+  },
+);
+
+scaffold(
+  'workspaceModuleLanguageForExtension should not be available under node_modules',
+  test,
+  new URL(
+    'fixtures-language-for-extension/node_modules/module-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  1, // expected number of assertions
+  {
+    parserForLanguage: { jsonp },
+    workspaceModuleLanguageForExtension: { xsonp: 'jsonp' },
+    shouldFailBeforeArchiveOperations: true,
+    onError(t, { error }) {
+      t.snapshot(sanitizePaths(error.message));
+    },
+  },
+);
+
+scaffold(
+  'workspaceCommonjsLanguageForExtension',
+  test,
+  new URL(
+    'fixtures-language-for-extension/packages/commonjs-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  assertionCount,
+  {
+    parserForLanguage: { jsonp },
+    workspaceCommonjsLanguageForExtension: { xsonp: 'jsonp' },
+  },
+);
+
+scaffold(
+  'workspaceCommonjsLanguageForExtension should not be available in module package',
+  test,
+  new URL(
+    'fixtures-language-for-extension/packages/module-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  1, // expected number of assertions
+  {
+    parserForLanguage: { jsonp },
+    workspaceCommonjsLanguageForExtension: { xsonp: 'jsonp' },
+    shouldFailBeforeArchiveOperations: true,
+    onError(t, { error }) {
+      t.snapshot(sanitizePaths(error.message));
+    },
+  },
+);
+
+scaffold(
+  'workspaceCommonjsLanguageForExtension should not be available under node_modules',
+  test,
+  new URL(
+    'fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  1, // expected number of assertions
+  {
+    parserForLanguage: { jsonp },
+    workspaceCommonjsLanguageForExtension: { xsonp: 'jsonp' },
+    shouldFailBeforeArchiveOperations: true,
+    onError(t, { error }) {
+      t.snapshot(sanitizePaths(error.message));
+    },
+  },
+);
+
+scaffold(
+  'package.json parsers override workspaceLanguageForExtension',
+  test,
+  new URL(
+    'fixtures-language-for-extension/packages/parsers-app/module.xsonp',
+    import.meta.url,
+  ).href,
+  assertions,
+  assertionCount,
+  {
+    parserForLanguage: { jsonp },
+    workspaceLanguageForExtension: { xsonp: 'text' },
+  },
+);
diff --git a/packages/compartment-mapper/test/missing-entry.test.js b/packages/compartment-mapper/test/missing-entry.test.js
index f53cff9bdd..4c2f70becc 100644
--- a/packages/compartment-mapper/test/missing-entry.test.js
+++ b/packages/compartment-mapper/test/missing-entry.test.js
@@ -1,6 +1,5 @@
 import 'ses';
 import test from 'ava';
-import path from 'path';
 import fs from 'fs';
 import url from 'url';
 import crypto from 'crypto';
@@ -11,9 +10,10 @@ import { makeReadPowers } from '../node-powers.js';
 const readPowers = makeReadPowers({ fs, url, crypto });
 
 test('missing entry', async t => {
-  const entry = url.pathToFileURL(
-    path.resolve('i-solemnly-swear-i-do-not-exist.js'),
-  );
+  const entry = new URL(
+    'fixtures-missing/i-solemnly-swear-i-do-not-exist.js',
+    import.meta.url,
+  ).href;
   await t.throwsAsync(
     makeAndHashArchive(readPowers, entry, {}).then(() => {}),
     {
diff --git a/packages/compartment-mapper/test/scaffold.js b/packages/compartment-mapper/test/scaffold.js
index a150378726..00ee4ea127 100644
--- a/packages/compartment-mapper/test/scaffold.js
+++ b/packages/compartment-mapper/test/scaffold.js
@@ -101,6 +101,9 @@ export function scaffold(
     languageForExtension = undefined,
     commonjsLanguageForExtension = undefined,
     moduleLanguageForExtension = undefined,
+    workspaceLanguageForExtension = undefined,
+    workspaceCommonjsLanguageForExtension = undefined,
+    workspaceModuleLanguageForExtension = undefined,
     additionalOptions = {},
   } = {},
 ) {
@@ -148,6 +151,9 @@ export function scaffold(
       languageForExtension,
       commonjsLanguageForExtension,
       moduleLanguageForExtension,
+      workspaceLanguageForExtension,
+      workspaceCommonjsLanguageForExtension,
+      workspaceModuleLanguageForExtension,
       ...additionalOptions,
     });
     const { namespace } = await application.import({
@@ -180,6 +186,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -221,6 +230,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -262,6 +274,9 @@ export function scaffold(
       languageForExtension,
       commonjsLanguageForExtension,
       moduleLanguageForExtension,
+      workspaceLanguageForExtension,
+      workspaceCommonjsLanguageForExtension,
+      workspaceModuleLanguageForExtension,
       ...additionalOptions,
     });
     return namespace;
@@ -283,6 +298,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
       const application = await parseArchive(archive, '<unknown>', {
@@ -325,6 +343,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
       const prefixArchive = new Uint8Array(archive.length + 10);
@@ -375,6 +396,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
       const application = await loadArchive(fakeRead, 'app.agar', {
@@ -434,6 +458,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -478,6 +505,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -529,6 +559,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -541,6 +574,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -575,6 +611,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
 
@@ -587,6 +626,9 @@ export function scaffold(
         languageForExtension,
         commonjsLanguageForExtension,
         moduleLanguageForExtension,
+        workspaceLanguageForExtension,
+        workspaceCommonjsLanguageForExtension,
+        workspaceModuleLanguageForExtension,
         ...additionalOptions,
       });
 
diff --git a/packages/compartment-mapper/test/snapshots/language-for-extension.test.js.md b/packages/compartment-mapper/test/snapshots/language-for-extension.test.js.md
new file mode 100644
index 0000000000..684f541900
--- /dev/null
+++ b/packages/compartment-mapper/test/snapshots/language-for-extension.test.js.md
@@ -0,0 +1,329 @@
+# Snapshot report for `test/language-for-extension.test.js`
+
+The actual snapshot is saved in `language-for-extension.test.js.snap`.
+
+Generated by [AVA](https://avajs.dev).
+
+## moduleLanguageForExtension should not be available in commonjs package / loadLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## moduleLanguageForExtension should not be available in commonjs package / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## moduleLanguageForExtension should not be available in commonjs package / mapNodeModules / loadFromMap / import
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## moduleLanguageForExtension should not be available in commonjs package / importLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## moduleLanguageForExtension should not be available in commonjs package / makeArchive / parseArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## moduleLanguageForExtension should not be available in commonjs package / makeArchive / parseArchive with a prefix
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## moduleLanguageForExtension should not be available in commonjs package / writeArchive / loadArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## moduleLanguageForExtension should not be available in commonjs package / writeArchive / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## moduleLanguageForExtension should not be available in commonjs package / mapNodeModules / makeArchiveFromMap / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## commonjsLanguageForExtension should not be available in module package / loadLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## commonjsLanguageForExtension should not be available in module package / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## commonjsLanguageForExtension should not be available in module package / mapNodeModules / loadFromMap / import
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## commonjsLanguageForExtension should not be available in module package / importLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## commonjsLanguageForExtension should not be available in module package / makeArchive / parseArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## commonjsLanguageForExtension should not be available in module package / makeArchive / parseArchive with a prefix
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## commonjsLanguageForExtension should not be available in module package / writeArchive / loadArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## commonjsLanguageForExtension should not be available in module package / writeArchive / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## commonjsLanguageForExtension should not be available in module package / mapNodeModules / makeArchiveFromMap / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceModuleLanguageForExtension should not be available in commonjs package / loadLocation
+
+> Snapshot 1
+
+    'Failed to load module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" in package "file://.../compartment-mapper/" (1 underlying failures: Cannot find file for internal module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" (with candidates "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.node", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.node") in package file://.../compartment-mapper/'
+
+## workspaceModuleLanguageForExtension should not be available in commonjs package / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    'Failed to load module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" in package "file://.../compartment-mapper/" (1 underlying failures: Cannot find file for internal module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" (with candidates "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.node", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.node") in package file://.../compartment-mapper/'
+
+## workspaceModuleLanguageForExtension should not be available in commonjs package / mapNodeModules / loadFromMap / import
+
+> Snapshot 1
+
+    'Failed to load module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" in package "file://.../compartment-mapper/" (1 underlying failures: Cannot find file for internal module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" (with candidates "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.node", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.node") in package file://.../compartment-mapper/'
+
+## workspaceModuleLanguageForExtension should not be available in commonjs package / importLocation
+
+> Snapshot 1
+
+    'Failed to load module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" in package "file://.../compartment-mapper/" (1 underlying failures: Cannot find file for internal module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" (with candidates "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.node", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.node") in package file://.../compartment-mapper/'
+
+## workspaceModuleLanguageForExtension should not be available in commonjs package / makeArchive / parseArchive
+
+> Snapshot 1
+
+    'Failed to load module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" in package "file://.../compartment-mapper/" (1 underlying failures: Cannot find file for internal module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" (with candidates "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.node", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.node") in package file://.../compartment-mapper/'
+
+## workspaceModuleLanguageForExtension should not be available in commonjs package / makeArchive / parseArchive with a prefix
+
+> Snapshot 1
+
+    'Failed to load module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" in package "file://.../compartment-mapper/" (1 underlying failures: Cannot find file for internal module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" (with candidates "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.node", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.node") in package file://.../compartment-mapper/'
+
+## workspaceModuleLanguageForExtension should not be available in commonjs package / writeArchive / loadArchive
+
+> Snapshot 1
+
+    'Failed to load module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" in package "file://.../compartment-mapper/" (1 underlying failures: Cannot find file for internal module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" (with candidates "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.node", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.node") in package file://.../compartment-mapper/'
+
+## workspaceModuleLanguageForExtension should not be available in commonjs package / writeArchive / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" in package "file://.../compartment-mapper/" (1 underlying failures: Cannot find file for internal module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" (with candidates "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.node", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.node") in package file://.../compartment-mapper/'
+
+## workspaceModuleLanguageForExtension should not be available in commonjs package / mapNodeModules / makeArchiveFromMap / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" in package "file://.../compartment-mapper/" (1 underlying failures: Cannot find file for internal module "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp" (with candidates "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp.node", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.js", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.json", "./test/fixtures-language-for-extension/package/commonjs-app/module.xsonp/index.node") in package file://.../compartment-mapper/'
+
+## workspaceModuleLanguageForExtension should not be available under node_modules / loadLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceModuleLanguageForExtension should not be available under node_modules / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceModuleLanguageForExtension should not be available under node_modules / mapNodeModules / loadFromMap / import
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceModuleLanguageForExtension should not be available under node_modules / importLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceModuleLanguageForExtension should not be available under node_modules / makeArchive / parseArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceModuleLanguageForExtension should not be available under node_modules / makeArchive / parseArchive with a prefix
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceModuleLanguageForExtension should not be available under node_modules / writeArchive / loadArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceModuleLanguageForExtension should not be available under node_modules / writeArchive / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceModuleLanguageForExtension should not be available under node_modules / mapNodeModules / makeArchiveFromMap / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available in module package / loadLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available in module package / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available in module package / mapNodeModules / loadFromMap / import
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available in module package / importLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available in module package / makeArchive / parseArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available in module package / makeArchive / parseArchive with a prefix
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available in module package / writeArchive / loadArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available in module package / writeArchive / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available in module package / mapNodeModules / makeArchiveFromMap / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../module-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../module-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available under node_modules / loadLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available under node_modules / mapNodeModules / importFromMap
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available under node_modules / mapNodeModules / loadFromMap / import
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available under node_modules / importLocation
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available under node_modules / makeArchive / parseArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available under node_modules / makeArchive / parseArchive with a prefix
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available under node_modules / writeArchive / loadArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available under node_modules / writeArchive / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
+
+## workspaceCommonjsLanguageForExtension should not be available under node_modules / mapNodeModules / makeArchiveFromMap / importArchive
+
+> Snapshot 1
+
+    'Failed to load module "./module.xsonp" in package "file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/" (1 underlying failures: Cannot parse module ./module.xsonp at file://.../compartment-mapper/test/fixtures-language-for-extension/node_modules/commonjs-app/module.xsonp, no parser configured for the language xsonp'
diff --git a/packages/compartment-mapper/test/snapshots/language-for-extension.test.js.snap b/packages/compartment-mapper/test/snapshots/language-for-extension.test.js.snap
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