Apply source field only in development parcel builds

crates/parcel-resolver/src/package_json.rs

@@ -584,9 +584,7 @@ impl PackageJson {
         for (key, value) in target {
           let matches = match key {
             ExportsKey::Condition(key) => {
-              *key == ExportsCondition::SOURCE
-                || *key == ExportsCondition::DEFAULT
-                || conditions.contains(*key)
+              *key == ExportsCondition::DEFAULT || conditions.contains(*key)
             }
             ExportsKey::CustomCondition(key) => custom_conditions.iter().any(|k| k == key),
             _ => false,

packages/core/package-manager/src/NodePackageManager.js

@@ -36,13 +36,19 @@ import {transformSync} from '@swc/core';
 // Package.json fields. Must match package_json.rs.
 const MAIN = 1 << 0;
 const SOURCE = 1 << 2;
+const SOURCE_CONDITION = 1 << 17;
 const ENTRIES =
   MAIN |
   (process.env.PARCEL_BUILD_ENV !== 'production' ||
   process.env.PARCEL_SELF_BUILD
     ? SOURCE
     : 0);
 
+const CONDITIONS =
+  process.env.PARCEL_BUILD_ENV !== 'production' || process.env.PARCEL_SELF_BUILD
+    ? SOURCE_CONDITION
+    : 0;
+
 const NODE_MODULES = `${path.sep}node_modules${path.sep}`;
 
 const IS_FILE = 1 << 0;
@@ -111,6 +117,7 @@ export class NodePackageManager implements PackageManager {
             },
       mode: 2,
       entries: ENTRIES,
+      conditions: CONDITIONS,
       packageExports: true,
       moduleDirResolver:
         process.versions.pnp != null

packages/dev/babel-register/babel-plugin-module-translate.js

@@ -9,6 +9,9 @@ function resolveSource(specifier, from) {
         if (pkg.source) {
           pkg.main = pkg.source;
         }
+        if (pkg.exports?.source) {
+          pkg.main = pkg.exports.source;
+        }
       }
       return pkg;
     },

packages/utils/node-resolver-core/src/Wrapper.js

@@ -783,8 +783,9 @@ function environmentToExportsConditions(
   const DEVELOPMENT = 1 << 8;
   const PRODUCTION = 1 << 9;
   const REACT_SERVER = 1 << 16;
+  const SOURCE = 1 << 17;
 
-  let conditions = 0;
+  let conditions = SOURCE;
   if (env.isBrowser()) {
     conditions |= BROWSER;
   }