diff --git a/.github/workflows/pr-checks.yml b/.github/workflows/pr-checks.yml
index ac61475d6..b1e131425 100644
--- a/.github/workflows/pr-checks.yml
+++ b/.github/workflows/pr-checks.yml
@@ -72,6 +72,33 @@ jobs:
           sarif_file: eslint.sarif
           category: eslint
 
+  changetool-tests:
+    name: changetool unit tests
+    permissions:
+      contents: read
+    runs-on: ubuntu-slim
+    timeout-minutes: 10
+
+    concurrency:
+      cancel-in-progress: ${{ github.event_name == 'pull_request' || false }}
+      group: pr-checks-changetool-tests-${{ github.ref }}-${{ github.event_name }}
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Set up Node.js
+        uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: 24
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run changetool unit tests
+        run: npm --workspace changetool test
+
   # These checks do not need to be run as part of the same matrix that we use for the `unit-tests`
   # job.
   other-checks:
diff --git a/eslint.config.mjs b/eslint.config.mjs
index 34fe49a9d..f82f07132 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -209,4 +209,18 @@ export default [
       ],
     },
   },
+  {
+    files: ["scripts/changetool/**/*.ts"],
+
+    languageOptions: {
+      parserOptions: {
+        project: "./scripts/changetool/tsconfig.json",
+      },
+    },
+
+    rules: {
+      "no-console": "off",
+      "import/extensions": "off",
+    },
+  },
 ];
diff --git a/package-lock.json b/package-lock.json
index 6e59f20e9..91bb6d7f4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,7 +9,8 @@
       "version": "4.37.10",
       "license": "MIT",
       "workspaces": [
-        "pr-checks"
+        "pr-checks",
+        "scripts/changetool"
       ],
       "dependencies": {
         "@actions/artifact": "^5.0.3",
@@ -2545,6 +2546,15 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/debug": {
+      "version": "4.1.13",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@types/debug/-/debug-4.1.13.tgz",
+      "integrity": "sha1-ItHMnVQtNZPK6nZPl0MGqzYobuc=",
+      "license": "MIT",
+      "dependencies": {
+        "@types/ms": "*"
+      }
+    },
     "node_modules/@types/estree": {
       "version": "1.0.8",
       "resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.8.tgz",
@@ -2578,6 +2588,21 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/mdast": {
+      "version": "4.0.4",
+      "resolved": "https://ms-feed-2.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@types/mdast/-/mdast-4.0.4.tgz",
+      "integrity": "sha1-fM9y7dLxqn3TQ34YDGQ3NYWATdY=",
+      "license": "MIT",
+      "dependencies": {
+        "@types/unist": "*"
+      }
+    },
+    "node_modules/@types/ms": {
+      "version": "2.1.0",
+      "resolved": "https://ms-feed-25.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@types/ms/-/ms-2.1.0.tgz",
+      "integrity": "sha1-BSqmekjszEMJ1/AZG35BQ0uQu3g=",
+      "license": "MIT"
+    },
     "node_modules/@types/node": {
       "version": "20.19.43",
       "resolved": "https://registry.npmjs.org/@types/node/-/node-20.19.43.tgz",
@@ -2637,6 +2662,12 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/unist": {
+      "version": "3.0.3",
+      "resolved": "https://ms-feed-25.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@types/unist/-/unist-3.0.3.tgz",
+      "integrity": "sha1-rKqw+RnOaczmKcLU7S60rcG2wgw=",
+      "license": "MIT"
+    },
     "node_modules/@typescript-eslint/eslint-plugin": {
       "version": "8.67.0",
       "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-8.67.0.tgz",
@@ -2991,6 +3022,346 @@
         "url": "https://opencollective.com/eslint"
       }
     },
+    "node_modules/@typescript/typescript-aix-ppc64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-aix-ppc64/-/typescript-aix-ppc64-7.0.2.tgz",
+      "integrity": "sha1-zcfOgdYPHgkDSWDd+x+4gNendrY=",
+      "cpu": [
+        "ppc64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "aix"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-darwin-arm64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-25.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-darwin-arm64/-/typescript-darwin-arm64-7.0.2.tgz",
+      "integrity": "sha1-pV/fz6WN9Y0n2yI3zealweNacjU=",
+      "cpu": [
+        "arm64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-darwin-x64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-25.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-darwin-x64/-/typescript-darwin-x64-7.0.2.tgz",
+      "integrity": "sha1-ONHJFygAqR1we+xk0qNwoBZjTbQ=",
+      "cpu": [
+        "x64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-freebsd-arm64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-2.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-freebsd-arm64/-/typescript-freebsd-arm64-7.0.2.tgz",
+      "integrity": "sha1-8f+IEAMLNdK1vg22otxlBGDqlPo=",
+      "cpu": [
+        "arm64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "freebsd"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-freebsd-x64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-2.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-freebsd-x64/-/typescript-freebsd-x64-7.0.2.tgz",
+      "integrity": "sha1-PYawPzU8WxupUWLrbONVM7/ClL0=",
+      "cpu": [
+        "x64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "freebsd"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-linux-arm": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-linux-arm/-/typescript-linux-arm-7.0.2.tgz",
+      "integrity": "sha1-rZS0HhruKk3MaimMe2fEM0X94y4=",
+      "cpu": [
+        "arm"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-linux-arm64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-linux-arm64/-/typescript-linux-arm64-7.0.2.tgz",
+      "integrity": "sha1-2TNNltbaxv+F2pyGVYiUjek56R8=",
+      "cpu": [
+        "arm64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-linux-loong64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-linux-loong64/-/typescript-linux-loong64-7.0.2.tgz",
+      "integrity": "sha1-KWWu5PyHM2ATnYk9qv5jl6KROK0=",
+      "cpu": [
+        "loong64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-linux-mips64el": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-linux-mips64el/-/typescript-linux-mips64el-7.0.2.tgz",
+      "integrity": "sha1-Goh6MRvtOoM/gL/Uqe03wnGTbPA=",
+      "cpu": [
+        "mips64el"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-linux-ppc64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-25.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-linux-ppc64/-/typescript-linux-ppc64-7.0.2.tgz",
+      "integrity": "sha1-i2PJsvRFs5PrTkPsIdoiXa3jV30=",
+      "cpu": [
+        "ppc64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-linux-riscv64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-2.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-linux-riscv64/-/typescript-linux-riscv64-7.0.2.tgz",
+      "integrity": "sha1-tuijXCibPql6kqQdRhqu7Q07NuE=",
+      "cpu": [
+        "riscv64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-linux-s390x": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-linux-s390x/-/typescript-linux-s390x-7.0.2.tgz",
+      "integrity": "sha1-Lvlmk75IYfbReWVCflsAnLvtGj4=",
+      "cpu": [
+        "s390x"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-linux-x64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-25.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-linux-x64/-/typescript-linux-x64-7.0.2.tgz",
+      "integrity": "sha1-cyacsLq6UK6gygYERaa4jlg/HOI=",
+      "cpu": [
+        "x64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "linux"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-netbsd-arm64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-2.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-netbsd-arm64/-/typescript-netbsd-arm64-7.0.2.tgz",
+      "integrity": "sha1-OjZJ+X+vohC05uN5jBXgZgXIqQE=",
+      "cpu": [
+        "arm64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "netbsd"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-netbsd-x64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-25.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-netbsd-x64/-/typescript-netbsd-x64-7.0.2.tgz",
+      "integrity": "sha1-R+xZSRpAxHDSgH3E0rglUo/Zeas=",
+      "cpu": [
+        "x64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "netbsd"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-openbsd-arm64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-17.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-openbsd-arm64/-/typescript-openbsd-arm64-7.0.2.tgz",
+      "integrity": "sha1-eWvo2gvZidij+5bygB44qDZbS68=",
+      "cpu": [
+        "arm64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "openbsd"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-openbsd-x64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-2.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-openbsd-x64/-/typescript-openbsd-x64-7.0.2.tgz",
+      "integrity": "sha1-03/ipynrlCwHbEVO5/GBX699Vg8=",
+      "cpu": [
+        "x64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "openbsd"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-sunos-x64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-17.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-sunos-x64/-/typescript-sunos-x64-7.0.2.tgz",
+      "integrity": "sha1-q6jTRkw1ZacER4m6upaRa9SrLIg=",
+      "cpu": [
+        "x64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "sunos"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-win32-arm64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-win32-arm64/-/typescript-win32-arm64-7.0.2.tgz",
+      "integrity": "sha1-ud5QoXGWOD9iYgtfnQovNK07YNc=",
+      "cpu": [
+        "arm64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "win32"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
+    "node_modules/@typescript/typescript-win32-x64": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-2.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@typescript/typescript-win32-x64/-/typescript-win32-x64-7.0.2.tgz",
+      "integrity": "sha1-zzt7DWzlY12spMjgHBic3N5H7Dw=",
+      "cpu": [
+        "x64"
+      ],
+      "dev": true,
+      "license": "Apache-2.0",
+      "optional": true,
+      "os": [
+        "win32"
+      ],
+      "engines": {
+        "node": ">=16.20.0"
+      }
+    },
     "node_modules/@typespec/ts-http-runtime": {
       "version": "0.3.2",
       "resolved": "https://registry.npmjs.org/@typespec/ts-http-runtime/-/ts-http-runtime-0.3.2.tgz",
@@ -4123,6 +4494,20 @@
         "url": "https://github.com/chalk/chalk?sponsor=1"
       }
     },
+    "node_modules/changetool": {
+      "resolved": "scripts/changetool",
+      "link": true
+    },
+    "node_modules/character-entities": {
+      "version": "2.0.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/character-entities/-/character-entities-2.0.2.tgz",
+      "integrity": "sha1-LQnC5yzZUjB2zLIRV9/2atQ/zCI=",
+      "license": "MIT",
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/wooorm"
+      }
+    },
     "node_modules/chownr": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/chownr/-/chownr-3.0.0.tgz",
@@ -4508,6 +4893,19 @@
         }
       }
     },
+    "node_modules/decode-named-character-reference": {
+      "version": "1.3.0",
+      "resolved": "https://ms-feed-17.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/decode-named-character-reference/-/decode-named-character-reference-1.3.0.tgz",
+      "integrity": "sha1-PkBgN2CHTC5YZ2kbWZ1zp9oltT8=",
+      "license": "MIT",
+      "dependencies": {
+        "character-entities": "^2.0.0"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/wooorm"
+      }
+    },
     "node_modules/deep-is": {
       "version": "0.1.4",
       "dev": true,
@@ -4551,6 +4949,15 @@
       "version": "2.3.1",
       "license": "ISC"
     },
+    "node_modules/dequal": {
+      "version": "2.0.3",
+      "resolved": "https://ms-feed-2.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/dequal/-/dequal-2.0.3.tgz",
+      "integrity": "sha1-JkQhTxmX057Q7g7OcjNUkKesZ74=",
+      "license": "MIT",
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/detect-libc": {
       "version": "2.1.2",
       "resolved": "https://registry.npmjs.org/detect-libc/-/detect-libc-2.1.2.tgz",
@@ -4561,6 +4968,19 @@
         "node": ">=8"
       }
     },
+    "node_modules/devlop": {
+      "version": "1.1.0",
+      "resolved": "https://ms-feed-25.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/devlop/-/devlop-1.1.0.tgz",
+      "integrity": "sha1-TbfCyk3G4Og0wwvnDJS7yXbccBg=",
+      "license": "MIT",
+      "dependencies": {
+        "dequal": "^2.0.0"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/wooorm"
+      }
+    },
     "node_modules/diff": {
       "version": "9.0.0",
       "resolved": "https://registry.npmjs.org/diff/-/diff-9.0.0.tgz",
@@ -7166,6 +7586,18 @@
         "node": ">= 0.8.0"
       }
     },
+    "node_modules/lite-matter": {
+      "version": "0.1.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/lite-matter/-/lite-matter-0.1.2.tgz",
+      "integrity": "sha1-NlO1r/xDs8OnKQcf/kw4/a4O1Ws=",
+      "license": "MIT",
+      "dependencies": {
+        "yaml": "^2.9.0"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/mgks"
+      }
+    },
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@@ -7289,6 +7721,43 @@
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@@ -7315,6 +7784,448 @@
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+        "@types/node": "^26.2.0",
+        "tsx": "^4.23.12",
+        "typescript": "^7.0.2"
+      }
+    },
+    "scripts/changetool/node_modules/@types/node": {
+      "version": "26.2.0",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/@types/node/-/node-26.2.0.tgz",
+      "integrity": "sha1-Wkh1qGL9qP3Ffej6pXm7gey6FoU=",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "undici-types": "~8.3.0"
+      }
+    },
+    "scripts/changetool/node_modules/typescript": {
+      "version": "7.0.2",
+      "resolved": "https://ms-feed-12.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/typescript/-/typescript-7.0.2.tgz",
+      "integrity": "sha1-nsdz15VKjBgsF8xbvVdaoovFFYI=",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "tsc": "bin/tsc"
+      },
+      "engines": {
+        "node": ">=16.20.0"
+      },
+      "optionalDependencies": {
+        "@typescript/typescript-aix-ppc64": "7.0.2",
+        "@typescript/typescript-darwin-arm64": "7.0.2",
+        "@typescript/typescript-darwin-x64": "7.0.2",
+        "@typescript/typescript-freebsd-arm64": "7.0.2",
+        "@typescript/typescript-freebsd-x64": "7.0.2",
+        "@typescript/typescript-linux-arm": "7.0.2",
+        "@typescript/typescript-linux-arm64": "7.0.2",
+        "@typescript/typescript-linux-loong64": "7.0.2",
+        "@typescript/typescript-linux-mips64el": "7.0.2",
+        "@typescript/typescript-linux-ppc64": "7.0.2",
+        "@typescript/typescript-linux-riscv64": "7.0.2",
+        "@typescript/typescript-linux-s390x": "7.0.2",
+        "@typescript/typescript-linux-x64": "7.0.2",
+        "@typescript/typescript-netbsd-arm64": "7.0.2",
+        "@typescript/typescript-netbsd-x64": "7.0.2",
+        "@typescript/typescript-openbsd-arm64": "7.0.2",
+        "@typescript/typescript-openbsd-x64": "7.0.2",
+        "@typescript/typescript-sunos-x64": "7.0.2",
+        "@typescript/typescript-win32-arm64": "7.0.2",
+        "@typescript/typescript-win32-x64": "7.0.2"
+      }
+    },
+    "scripts/changetool/node_modules/undici-types": {
+      "version": "8.3.0",
+      "resolved": "https://ms-feed-17.pkgs.visualstudio.com/1es-public/_packaging/npm-public/npm/registry/undici-types/-/undici-types-8.3.0.tgz",
+      "integrity": "sha1-ROn8nzJEZIzeo15Pm7LWgelBCAk=",
+      "dev": true,
+      "license": "MIT"
     }
   }
 }
diff --git a/package.json b/package.json
index da24ad389..ce523a32d 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,8 @@
   },
   "license": "MIT",
   "workspaces": [
-    "pr-checks"
+    "pr-checks",
+    "scripts/changetool"
   ],
   "dependencies": {
     "@actions/artifact": "^5.0.3",
diff --git a/scripts/changetool/cli/validate.test.ts b/scripts/changetool/cli/validate.test.ts
new file mode 100644
index 000000000..ac54972fd
--- /dev/null
+++ b/scripts/changetool/cli/validate.test.ts
@@ -0,0 +1,200 @@
+import assert from "node:assert/strict";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import { describe, it } from "node:test";
+
+import {
+  isValidChangenoteContent,
+  isValidChangenoteFile,
+  isValidChangenoteFilename,
+  hasValidChangenoteCategory,
+  VALID_CHANGE_NOTE_CATEGORIES,
+} from "./validate.ts";
+
+async function withTmpFile<T>(
+  baseFileName: string,
+  contents: string,
+  body: (filePath: string) => Promise<T>,
+): Promise<T> {
+  const tmpDir = fs.mkdtempSync(
+    path.join(os.tmpdir(), "changetool-validate-test-"),
+  );
+  try {
+    const filePath = path.join(tmpDir, baseFileName);
+    fs.writeFileSync(filePath, contents);
+    return await body(filePath);
+  } finally {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+  }
+}
+
+await describe("isValidChangenoteContent", async () => {
+  await it("recognizes an unordered Markdown list", async () => {
+    const inputs = [
+      "- One changenote entry",
+      "- First item\n- Second item",
+      "\n\n\n\n- Fixed a bug\n- Added a feature",
+    ];
+
+    for (const input of inputs) {
+      assert.equal(isValidChangenoteContent(input), true);
+    }
+  });
+
+  await it("does not recognize non-Markdown text", async () => {
+    const inputs = [
+      "This is not a list.",
+      '["this", "is", "JSON"]',
+      "---",
+      "***",
+      "___",
+      "paragraph",
+    ];
+
+    for (const input of inputs) {
+      assert.equal(isValidChangenoteContent(input), false);
+    }
+  });
+
+  await it("does not recognize ordered Markdown lists", async () => {
+    const inputs = [
+      "1. First item\n2. Second item",
+      "\n\n\n1. First item\n1. Second item",
+    ];
+
+    for (const input of inputs) {
+      assert.equal(isValidChangenoteContent(input), false);
+    }
+  });
+
+  await it("requires all list items to use a hyphen bullet", async () => {
+    const inputs = [
+      "* Fixed a bug\n* Added feature",
+      "+ Fixed a bug\n+ Added feature",
+      "- Fixed a bug\n* Added feature",
+      "- Fixed a bug\n+ Added feature",
+      "- Fixed a bug\n  * Added feature\n    + Updated docs",
+      "\n\n\n* Fixed a bug",
+      "\n\n\n+ Fixed a bug",
+      "---\n* Fixed a bug\n* Added feature",
+    ] as const;
+
+    for (const input of inputs) {
+      assert.equal(isValidChangenoteContent(input), false);
+    }
+  });
+
+  await it("does not contain other Markdown elements", async () => {
+    const inputs = [
+      "- Fixed a bug\n\nParagraph of text",
+      "- Fixed a bug\n\n* Added a feature",
+      "# Header\n- Fixed a bug",
+      "- Fixed a bug\n## Subheader",
+    ];
+
+    for (const input of inputs) {
+      assert.equal(isValidChangenoteContent(input), false);
+    }
+  });
+});
+
+await describe("isValidChangenoteFilename", async () => {
+  await it("accepts valid filenames", async () => {
+    const inputs = [
+      "2023-01-01-fix-bug.md",
+      "2023-12-31-add-feature.md",
+      "2023-06-15-update-docs.md",
+    ];
+
+    for (const input of inputs) {
+      assert.equal(isValidChangenoteFilename(input), true);
+    }
+  });
+
+  await it("rejects invalid filenames", async () => {
+    const inputs = [
+      "missing-date-from-filename.md",
+      "2021-01-01.md",
+      "2026-12-19-wrong-file-name-extension.txt",
+    ];
+
+    for (const input of inputs) {
+      assert.equal(isValidChangenoteFilename(input), false);
+    }
+  });
+});
+
+await describe("hasValidChangenoteCategory", async () => {
+  await it("accepts valid categories", async () => {
+    for (const category of Object.keys(VALID_CHANGE_NOTE_CATEGORIES)) {
+      const frontmatter = { category };
+      assert.equal(hasValidChangenoteCategory(frontmatter), true);
+    }
+  });
+
+  await it("rejects invalid categories", async () => {
+    const inputs = [
+      "",
+      "invalid-category",
+      "bug-fix",
+      "new-feature",
+      "security-patch",
+      "miscellaneous",
+      "documentation",
+    ];
+
+    for (const category of inputs) {
+      const frontmatter = { category };
+      assert.equal(hasValidChangenoteCategory(frontmatter), false);
+    }
+  });
+
+  await it("reject missing category", async () => {
+    assert.equal(hasValidChangenoteCategory({}), false);
+    assert.equal(hasValidChangenoteCategory({ category: null }), false);
+    assert.equal(hasValidChangenoteCategory({ category: undefined }), false);
+  });
+});
+
+await describe("isValidChangenoteFile", async () => {
+  await it("accepts a valid change-note file", async () => {
+    await withTmpFile(
+      "2026-01-01-fix-bug.md",
+      "---\ncategory: fix\n---\n- Fixed a bug\n",
+      async (filePath) => {
+        assert.equal(isValidChangenoteFile(filePath), true);
+      },
+    );
+  });
+
+  await it("rejects invalid filename", async () => {
+    await withTmpFile(
+      "fix-bug.md",
+      "---\ncategory: fix\n---\n- Fixed a bug\n",
+      async (filePath) => {
+        assert.equal(isValidChangenoteFile(filePath), false);
+      },
+    );
+  });
+
+  await it("rejects missing frontmatter", async () => {
+    await withTmpFile(
+      "2026-01-01-fix-bug.md",
+      "- Fixed a bug\n",
+      async (filePath) => {
+        assert.equal(isValidChangenoteFile(filePath), false);
+      },
+    );
+  });
+
+  await it("rejects invalid Markdown", async () => {
+    await withTmpFile(
+      "2026-01-01-fix-bug.md",
+      "---\ncategory: fix\n---\n* Fixed a bug\n",
+      async (filePath) => {
+        assert.equal(isValidChangenoteFile(filePath), false);
+      },
+    );
+  });
+});
diff --git a/scripts/changetool/cli/validate.ts b/scripts/changetool/cli/validate.ts
new file mode 100644
index 000000000..3c83276f3
--- /dev/null
+++ b/scripts/changetool/cli/validate.ts
@@ -0,0 +1,121 @@
+import * as fs from "node:fs";
+import * as path from "node:path";
+
+import { matter } from "lite-matter";
+import type { List, ListItem } from "mdast";
+import { fromMarkdown } from "mdast-util-from-markdown";
+
+// Regex for filename: YYYY-MM-DD-id.md
+const VALID_CHANGE_NOTE_FILENAME_PATTERN =
+  /^(\d{4})-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])-([a-z0-9]+(?:-[a-z0-9]+)*)\.md$/;
+
+export const VALID_CHANGE_NOTE_CATEGORIES = {
+  breaking: "Breaking Changes",
+  feature: "New Features",
+  improvement: "Improvements",
+  securityFix: "Security Fixes",
+  fix: "Bug Fixes",
+  unship: "Removed Features",
+  deprecation: "Deprecations",
+  knownIssue: "Known Issues",
+  misc: "Miscellaneous",
+};
+
+/**
+ * Validates that the given Markdown string meets the criteria for a change-note, which is:
+ * - A single unordered list
+ * - Each list item must start with a hyphen (-)
+ * - No other Markdown elements are allowed
+ * @param content The Markdown string to validate
+ * @returns True if the string is a valid change-note, false otherwise
+ */
+export function isValidChangenoteContent(content: string): boolean {
+  const ast = fromMarkdown(content);
+  const lines = content.split("\n");
+
+  function listHasHyphenBullets(node: List | ListItem): boolean {
+    if (node.type === "list") {
+      return node.children.every(listHasHyphenBullets);
+    }
+
+    const line = lines[node.position!.start.line - 1].trim();
+    return (
+      line.startsWith("-") &&
+      node.children.every(
+        (child) => child.type !== "list" || listHasHyphenBullets(child),
+      )
+    );
+  }
+
+  return (
+    ast.children.length === 1 &&
+    ast.children[0].type === "list" &&
+    ast.children[0].ordered === false &&
+    listHasHyphenBullets(ast.children[0])
+  );
+}
+
+/**
+ * Validates that the given filename meets the criteria for a change-note filename.
+ * @param filename The name of the change-note file to validate.
+ * @returns True if the filename is valid, false otherwise.
+ */
+export function isValidChangenoteFilename(filename: string): boolean {
+  return filename.match(VALID_CHANGE_NOTE_FILENAME_PATTERN) !== null;
+}
+
+/**
+ * Validates that the given frontmatter has a valid change-note category.
+ * @param frontmatter The frontmatter object to validate.
+ * @returns True if the frontmatter has a valid category, false otherwise.
+ */
+export function hasValidChangenoteCategory(
+  frontmatter: Record<string, unknown>,
+): boolean {
+  const category = frontmatter["category"];
+  return (
+    typeof category === "string" &&
+    Object.hasOwn(VALID_CHANGE_NOTE_CATEGORIES, category)
+  );
+}
+
+/**
+ * Validates that the given change-note file meets all of the criteria for a change-note.
+ * @param filename The name of the change-note file to validate.
+ * @returns True if the file is a valid change-note, false otherwise.
+ */
+export function isValidChangenoteFile(filename: string): boolean {
+  let isValid: boolean = true;
+
+  let fileData: string | undefined;
+  try {
+    fileData = fs.readFileSync(filename, "utf8");
+  } catch (error) {
+    console.error(`${filename}: failed to read file`, error);
+    return false;
+  }
+
+  const { data: frontmatter, content } = matter(fileData);
+
+  if (!isValidChangenoteFilename(path.basename(filename))) {
+    isValid = false;
+    console.error(
+      `${filename}: invalid filename; must match pattern YYYY-MM-DD-id.md`,
+    );
+  }
+  if (!hasValidChangenoteCategory(frontmatter)) {
+    isValid = false;
+    const categories = Object.keys(VALID_CHANGE_NOTE_CATEGORIES).join(", ");
+    console.error(
+      `${filename}: invalid category; must be one of: ${categories}`,
+    );
+  }
+  if (!isValidChangenoteContent(content)) {
+    isValid = false;
+    console.error(
+      `${filename}: invalid Markdown; content must be a single unordered list with hyphen bullets and no other Markdown elements`,
+    );
+  }
+
+  return isValid;
+}
diff --git a/scripts/changetool/index.ts b/scripts/changetool/index.ts
new file mode 100644
index 000000000..249448b3f
--- /dev/null
+++ b/scripts/changetool/index.ts
@@ -0,0 +1,51 @@
+import { pathToFileURL } from "node:url";
+import { parseArgs } from "node:util";
+
+import { isValidChangenoteFile } from "./cli/validate.ts";
+
+const entryPoint = process.argv[1];
+if (entryPoint && import.meta.url === pathToFileURL(entryPoint).href) {
+  try {
+    process.exit(main());
+  } catch (error) {
+    console.error(error);
+    process.exit(1);
+  }
+}
+
+function main(): number {
+  const { positionals } = parseArgs({
+    allowPositionals: true,
+    strict: true,
+  });
+  const [command, ...paths] = positionals;
+  switch (command) {
+    case undefined:
+    case "help":
+      return usage();
+    case "validate":
+      return validate(paths);
+    default:
+      console.error(`Unknown command: ${command}`);
+      return 1;
+  }
+}
+
+function usage(): number {
+  console.log("Usage: changetool validate <path> [<path> ...]");
+  return 0;
+}
+
+function validate(paths: string[]): number {
+  let valid = true;
+  if (paths.length === 0) {
+    console.error("error: no paths provided (see 'help' command for usage)");
+    return 1;
+  }
+  for (const path of paths) {
+    if (!isValidChangenoteFile(path)) {
+      valid = false;
+    }
+  }
+  return valid ? 0 : 1;
+}
diff --git a/scripts/changetool/package.json b/scripts/changetool/package.json
new file mode 100644
index 000000000..7eb8ceb9b
--- /dev/null
+++ b/scripts/changetool/package.json
@@ -0,0 +1,21 @@
+{
+  "name": "changetool",
+  "version": "1.0.0",
+  "private": true,
+  "description": "Validates change-notes and merges them into CHANGELOG.md",
+  "license": "MIT",
+  "type": "module",
+  "scripts": {
+    "start": "tsx index.ts",
+    "test": "node --test --experimental-strip-types cli/*.test.ts"
+  },
+  "devDependencies": {
+    "@types/node": "^26.2.0",
+    "tsx": "^4.23.12",
+    "typescript": "^7.0.2"
+  },
+  "dependencies": {
+    "lite-matter": "^0.1.2",
+    "mdast-util-from-markdown": "^2.0.3"
+  }
+}
diff --git a/scripts/changetool/tsconfig.json b/scripts/changetool/tsconfig.json
new file mode 100644
index 000000000..ee76bd186
--- /dev/null
+++ b/scripts/changetool/tsconfig.json
@@ -0,0 +1,11 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "module": "preserve",
+    "allowImportingTsExtensions": true,
+    "rootDir": ".",
+    "sourceMap": false
+  },
+  "include": ["./**/*.ts"],
+  "exclude": ["node_modules"]
+}
diff --git a/tsconfig.json b/tsconfig.json
index 66545447c..d2b39b5ef 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -37,5 +37,5 @@
       "@octokit/core/dist-types/types": ["./node_modules/@octokit/core/dist-types/types.d.ts"]
     },
   },
-  "exclude": ["node_modules", "pr-checks"]
+  "exclude": ["node_modules", "pr-checks", "scripts/changetool"]
 }