Bump TypeScript to 5.9.

apps/api-extractor/package.json

@@ -75,7 +75,7 @@
     "resolve": "~1.22.1",
     "semver": "~7.5.4",
     "source-map": "~0.6.1",
-    "typescript": "5.8.2"
+    "typescript": "5.9.3"
   },
   "devDependencies": {
     "@rushstack/heft": "1.2.7",

apps/lockfile-explorer-web/package.json

@@ -27,7 +27,7 @@
     "@types/react-dom": "19.2.3",
     "eslint": "~9.37.0",
     "local-web-rig": "workspace:*",
-    "typescript": "5.8.2"
+    "typescript": "5.9.3"
   },
   "sideEffects": false
 }

apps/rush-mcp-server/package.json

@@ -65,7 +65,7 @@
     "@rushstack/heft": "workspace:*",
     "eslint": "~9.37.0",
     "local-node-rig": "workspace:*",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "@types/node": "20.17.19"
   },
   "sideEffects": [

apps/trace-import/package.json

@@ -23,7 +23,7 @@
     "@rushstack/ts-command-line": "workspace:*",
     "resolve": "~1.22.1",
     "semver": "~7.5.4",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   },
   "devDependencies": {
     "@rushstack/heft": "workspace:*",

apps/zipsync/package.json

@@ -20,7 +20,7 @@
   "dependencies": {
     "@rushstack/terminal": "workspace:*",
     "@rushstack/ts-command-line": "workspace:*",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "@rushstack/lookup-by-path": "workspace:*"
   },
   "devDependencies": {

build-tests-samples/heft-node-basic-tutorial/package.json

@@ -19,6 +19,6 @@
     "@types/node": "20.17.19",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests-samples/heft-node-jest-tutorial/package.json

@@ -18,6 +18,6 @@
     "@types/node": "20.17.19",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests-samples/heft-serverless-stack-tutorial/package.json

@@ -30,6 +30,6 @@
     "constructs": "~10.0.98",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests-samples/heft-storybook-v6-react-tutorial-storykit/package.json

@@ -52,7 +52,7 @@
     "react": "~17.0.2",
     "style-loader": "~2.0.0",
     "terser-webpack-plugin": "~3.0.8",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~4.47.0"
   },
   "devDependencies": {

build-tests-samples/heft-storybook-v6-react-tutorial/package.json

@@ -38,7 +38,7 @@
     "local-eslint-config": "workspace:*",
     "source-map-loader": "~1.1.3",
     "style-loader": "~2.0.0",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~4.47.0"
   }
 }

build-tests-samples/heft-storybook-v9-react-tutorial-storykit/package.json

@@ -47,7 +47,7 @@
     "react": "~19.2.3",
     "style-loader": "~2.0.0",
     "terser-webpack-plugin": "~3.0.8",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~5.105.2",
     "storybook": "~9.1.6",
     "@testing-library/dom": "~7.21.4"

build-tests-samples/heft-storybook-v9-react-tutorial/package.json

@@ -39,7 +39,7 @@
     "local-eslint-config": "workspace:*",
     "source-map-loader": "~1.1.3",
     "style-loader": "~2.0.0",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~5.105.2",
     "storybook": "~9.1.6",
     "@testing-library/dom": "~7.21.4",

build-tests-samples/heft-webpack-basic-tutorial/package.json

@@ -30,7 +30,7 @@
     "local-eslint-config": "workspace:*",
     "source-map-loader": "~3.0.1",
     "style-loader": "~3.3.1",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~5.105.2"
   }
 }

build-tests-samples/packlets-tutorial/package.json

@@ -16,6 +16,6 @@
     "@rushstack/heft-typescript-plugin": "workspace:*",
     "@types/node": "20.17.19",
     "eslint": "~8.57.0",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests-subspace/typescript-newest-test/package.json

@@ -35,7 +35,7 @@
     "@rushstack/heft": "workspace:*",
     "eslint": "~9.25.1",
     "local-node-rig": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   },
   "dependenciesMeta": {
     "@rushstack/heft": {

build-tests/eslint-7-11-test/package.json

@@ -38,6 +38,6 @@
     "@typescript-eslint/parser": "~6.19.0",
     "eslint": "7.11.0",
     "local-node-rig": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/eslint-7-7-test/package.json

@@ -38,6 +38,6 @@
     "@typescript-eslint/parser": "~6.19.0",
     "eslint": "7.7.0",
     "local-node-rig": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/eslint-7-test/package.json

@@ -38,6 +38,6 @@
     "@typescript-eslint/parser": "~6.19.0",
     "eslint": "~7.30.0",
     "local-node-rig": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/eslint-8-test/package.json

@@ -38,6 +38,6 @@
     "@typescript-eslint/parser": "~8.56.1",
     "eslint": "~8.57.0",
     "local-node-rig": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/eslint-9-test/package.json

@@ -38,6 +38,6 @@
     "@types/node": "20.17.19",
     "@typescript-eslint/parser": "~8.56.1",
     "eslint": "~9.37.0",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/eslint-bulk-suppressions-test-flat/package.json

@@ -14,6 +14,6 @@
     "@typescript-eslint/parser": "~8.56.1",
     "eslint": "~9.37.0",
     "local-node-rig": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/eslint-bulk-suppressions-test-legacy/package.json

@@ -17,6 +17,6 @@
     "eslint-8.23": "npm:eslint@8.23.1",
     "eslint-oldest": "npm:eslint@8.6.0",
     "local-node-rig": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/eslint-bulk-suppressions-test/package.json

@@ -15,6 +15,6 @@
     "@typescript-eslint/parser": "~8.56.1",
     "eslint": "~8.57.0",
     "local-node-rig": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/hashed-folder-copy-plugin-webpack5-test/package.json

@@ -16,7 +16,7 @@
     "@rushstack/heft-webpack5-plugin": "workspace:*",
     "@types/webpack-env": "1.18.8",
     "html-webpack-plugin": "~5.5.0",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack-bundle-analyzer": "~4.5.0",
     "webpack": "~5.105.2"
   }

build-tests/heft-example-lifecycle-plugin/package.json

@@ -17,6 +17,6 @@
     "@types/node": "20.17.19",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-example-plugin-01/package.json

@@ -21,6 +21,6 @@
     "@types/tapable": "1.0.6",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-example-plugin-02/package.json

@@ -26,6 +26,6 @@
     "eslint": "~9.37.0",
     "heft-example-plugin-01": "workspace:*",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-fastify-test/package.json

@@ -19,7 +19,7 @@
     "@types/node": "20.17.19",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   },
   "dependencies": {
     "fastify": "~3.16.1"

build-tests/heft-jest-preset-test/package.json

@@ -18,6 +18,6 @@
     "@types/heft-jest": "1.0.1",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-jest-reporters-test/package.json

@@ -20,6 +20,6 @@
     "@types/node": "20.17.19",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-minimal-rig-test/package.json

@@ -9,7 +9,7 @@
     "_phase:build": ""
   },
   "dependencies": {
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "@microsoft/api-extractor": "workspace:*",
     "@rushstack/heft-api-extractor-plugin": "workspace:*",
     "@rushstack/heft-jest-plugin": "workspace:*",

build-tests/heft-node-everything-esm-module-test/package.json

@@ -26,6 +26,6 @@
     "heft-example-plugin-02": "workspace:*",
     "local-eslint-config": "workspace:*",
     "tslint": "~5.20.1",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-node-everything-test/package.json

@@ -28,6 +28,6 @@
     "heft-example-plugin-02": "workspace:*",
     "local-eslint-config": "workspace:*",
     "tslint": "~5.20.1",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-parameter-plugin-test/package.json

@@ -18,6 +18,6 @@
     "@types/heft-jest": "1.0.1",
     "@types/node": "20.17.19",
     "heft-parameter-plugin": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-parameter-plugin/package.json

@@ -16,7 +16,7 @@
     "@types/node": "20.17.19",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   },
   "dependencies": {
     "@rushstack/node-core-library": "workspace:*"

build-tests/heft-rspack-everything-test/package.json

@@ -24,7 +24,7 @@
     "@types/node": "20.17.19",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "@rspack/core": "~1.6.0-beta.0"
   }
 }

build-tests/heft-sass-test/package.json

@@ -33,7 +33,7 @@
     "react-dom": "~19.2.3",
     "react": "~19.2.3",
     "style-loader": "~2.0.0",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~4.47.0"
   },
   "dependencies": {

build-tests/heft-swc-test/package.json

@@ -21,6 +21,6 @@
     "@types/webpack-env": "1.18.8",
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-typescript-composite-test/package.json

@@ -20,6 +20,6 @@
     "eslint": "~9.37.0",
     "local-eslint-config": "workspace:*",
     "tslint": "~5.20.1",
-    "typescript": "~5.8.2"
+    "typescript": "~5.9.3"
   }
 }

build-tests/heft-webpack4-everything-test/package.json

@@ -28,7 +28,7 @@
     "local-eslint-config": "workspace:*",
     "source-map-loader": "~1.1.3",
     "tslint": "~5.20.1",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~4.47.0"
   }
 }

build-tests/heft-webpack5-everything-test/package.json

@@ -31,7 +31,7 @@
     "local-eslint-config": "workspace:*",
     "source-map-loader": "~3.0.1",
     "tslint": "~5.20.1",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~5.105.2"
   }
 }

build-tests/localization-plugin-test-03/package.json

@@ -20,7 +20,7 @@
     "html-webpack-plugin": "~4.5.2",
     "local-node-rig": "workspace:*",
     "ts-loader": "6.0.0",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~4.47.0",
     "webpack-bundle-analyzer": "~4.5.0",
     "webpack-dev-server": "~4.9.3"

build-tests/set-webpack-public-path-plugin-test/package.json

@@ -19,7 +19,7 @@
     "@types/webpack-env": "1.18.8",
     "eslint": "~8.57.0",
     "html-webpack-plugin": "~5.5.0",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~5.105.2"
   }
 }

build-tests/webpack-local-version-test/package.json

@@ -16,7 +16,7 @@
     "@types/webpack-env": "1.18.8",
     "eslint": "~9.25.1",
     "html-webpack-plugin": "~5.5.0",
-    "typescript": "~5.8.2",
+    "typescript": "~5.9.3",
     "webpack": "~5.105.0"
   }
 }

common/changes/@microsoft/api-extractor/ts-5.9_2026-01-13-21-56.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/api-extractor",
+      "comment": "Upgrade the bundled compiler engine to TypeScript 5.9.3",
+      "type": "minor"
+    }
+  ],
+  "packageName": "@microsoft/api-extractor"
+}

common/changes/@microsoft/rush/ts-5.9_2026-03-23-19-54.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/rush",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@microsoft/rush"
+}