[rush] Fix "rush-pnpm patch-commit" writing absolute paths into pnpm-config.json

common/changes/@microsoft/rush/fix-rush-pnpm-patch-absolute-paths_2026-07-14-18-30.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/rush",
+      "comment": "Fix an issue where \"rush-pnpm patch-commit\" rewrote the pre-existing \"globalPatchedDependencies\" entries in pnpm-config.json using absolute paths when running with pnpm >= 9.",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@microsoft/rush"
+}

libraries/rush-lib/src/logic/pnpm/PnpmOptionsConfiguration.ts

@@ -1,7 +1,9 @@
 // Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
 // See LICENSE in the project root for license information.
 
-import { JsonFile, type JsonObject } from '@rushstack/node-core-library';
+import * as path from 'node:path';
+
+import { JsonFile, type JsonObject, Path } from '@rushstack/node-core-library';
 import { NonProjectConfigurationFile } from '@rushstack/heft-config-file';
 import { ConsoleTerminalProvider, Terminal } from '@rushstack/terminal';
 
@@ -211,6 +213,7 @@ export interface IPnpmOptionsJson extends IPackageManagerOptionsJsonBase {
  */
 export class PnpmOptionsConfiguration extends PackageManagerOptionsConfigurationBase {
   private readonly _json: JsonObject;
+  private readonly _commonTempFolder: string;
   private _globalPatchedDependencies: Record<string, string> | undefined;
 
   /**
@@ -556,6 +559,7 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
   private constructor(json: IPnpmOptionsJson, commonTempFolder: string, jsonFilename?: string) {
     super(json);
     this._json = json;
+    this._commonTempFolder = commonTempFolder;
     this.jsonFilename = jsonFilename;
     this.pnpmStore = json.pnpmStore || 'local';
     if (EnvironmentConfiguration.pnpmStorePathOverride) {
@@ -636,8 +640,25 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
 
   /**
    * Updates patchedDependencies field of the PNPM options in the common/config/rush/pnpm-config.json file.
+   *
+   * @remarks
+   * When running "pnpm patch-commit"/"pnpm patch-remove" (pnpm 9 and newer), pnpm rewrites the
+   * pre-existing entries using absolute paths pointing into the common/temp folder. Normalize any such
+   * value back to a path relative to the common/temp folder (e.g. "patches/example\@1.0.0.patch") so the location
+   * of the local checkout does not leak into pnpm-config.json.
    */
   public updateGlobalPatchedDependencies(patchedDependencies: Record<string, string> | undefined): void {
+    if (patchedDependencies) {
+      const normalized: Record<string, string> = {};
+      for (const [dependency, patchPath] of Object.entries(patchedDependencies)) {
+        normalized[dependency] =
+          path.isAbsolute(patchPath) && Path.isUnder(patchPath, this._commonTempFolder)
+            ? Path.convertToSlashes(path.relative(this._commonTempFolder, patchPath))
+            : patchPath;
+      }
+      patchedDependencies = normalized;
+    }
+
     this._globalPatchedDependencies = patchedDependencies;
     this._json.globalPatchedDependencies = patchedDependencies;
     if (this.jsonFilename) {

libraries/rush-lib/src/logic/pnpm/test/PnpmOptionsConfiguration.test.ts

@@ -169,4 +169,57 @@ describe(PnpmOptionsConfiguration.name, () => {
       }
     });
   });
+
+  describe('updateGlobalPatchedDependencies', () => {
+    function update(
+      patchedDependencies: Record<string, string> | undefined
+    ): Record<string, string> | undefined {
+      // No jsonFilename, so updateGlobalPatchedDependencies won't try to write to disk
+      const pnpmConfiguration: PnpmOptionsConfiguration = PnpmOptionsConfiguration.loadFromJsonObject(
+        {},
+        fakeCommonTempFolder
+      );
+      pnpmConfiguration.updateGlobalPatchedDependencies(patchedDependencies);
+      return pnpmConfiguration.globalPatchedDependencies;
+    }
+
+    it('converts absolute patch paths under the common temp folder back to relative paths', () => {
+      // pnpm >= 9 "patch-commit"/"patch-remove" rewrite pre-existing "patchedDependencies" entries
+      // using absolute paths pointing into the common/temp folder
+      expect(
+        update({
+          'example@1.0.0': path.join(fakeCommonTempFolder, 'patches', 'example@1.0.0.patch'),
+          '@scope/example2@2.0.0': path.join(fakeCommonTempFolder, 'patches', '@scope__example2@2.0.0.patch')
+        })
+      ).toEqual({
+        'example@1.0.0': 'patches/example@1.0.0.patch',
+        '@scope/example2@2.0.0': 'patches/@scope__example2@2.0.0.patch'
+      });
+    });
+
+    it('leaves relative patch paths unchanged', () => {
+      expect(
+        update({
+          'example@1.0.0': 'patches/example@1.0.0.patch'
+        })
+      ).toEqual({
+        'example@1.0.0': 'patches/example@1.0.0.patch'
+      });
+    });
+
+    it('leaves absolute patch paths outside the common temp folder unchanged', () => {
+      const outsidePath: string = path.join(path.sep, 'somewhere', 'else', 'example@1.0.0.patch');
+      expect(
+        update({
+          'example@1.0.0': outsidePath
+        })
+      ).toEqual({
+        'example@1.0.0': outsidePath
+      });
+    });
+
+    it('passes through undefined', () => {
+      expect(update(undefined)).toBeUndefined();
+    });
+  });
 });