diff --git a/.github/workflows/update-terminus-data.yml b/.github/workflows/update-terminus-data.yml
new file mode 100644
index 0000000000..a7d9152564
--- /dev/null
+++ b/.github/workflows/update-terminus-data.yml
@@ -0,0 +1,57 @@
+name: Update Terminus reference data
+
+on:
+  schedule:
+    # Weekly fallback poll — catches any release the dispatch trigger misses.
+    - cron: "0 13 * * 1"
+  workflow_dispatch: {}
+  repository_dispatch:
+    # Fired by pantheon-systems/terminus on release publish, once that
+    # workflow step exists. Inert (never sent) until then.
+    types: [terminus-release]
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  update-data:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: "8.3"
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Update commands.json and terminusReleases.json
+        run: npm run update-terminus-data
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Open PR if data changed
+        uses: peter-evans/create-pull-request@v6
+        with:
+          commit-message: "chore: update Terminus commands and releases data"
+          title: "chore: update Terminus commands and releases data"
+          body: |
+            Automated update of `src/source/data/commands.json` and
+            `src/source/data/terminusReleases.json` from the latest
+            [Terminus release](https://github.com/pantheon-systems/terminus/releases/latest).
+
+            Generated by `.github/workflows/update-terminus-data.yml`.
+          branch: chore/update-terminus-data
+          delete-branch: true
+          add-paths: |
+            src/source/data/commands.json
+            src/source/data/terminusReleases.json
diff --git a/package.json b/package.json
index 19bbe8de9b..777e7efdb9 100644
--- a/package.json
+++ b/package.json
@@ -8,6 +8,7 @@
   "scripts": {
     "audit": "tsx scripts/audit.ts",
     "evaluate": "tsx --env-file=.env scripts/evaluate.ts",
+    "update-terminus-data": "tsx scripts/update-terminus-data.ts",
     "update": "tsx seed/update.ts",
     "build": "next build",
     "coverage": "vitest run --coverage",
diff --git a/scripts/update-terminus-data.ts b/scripts/update-terminus-data.ts
new file mode 100644
index 0000000000..4d4c0f6c9e
--- /dev/null
+++ b/scripts/update-terminus-data.ts
@@ -0,0 +1,129 @@
+import { execFileSync } from "child_process";
+import { mkdtempSync, rmSync, writeFileSync } from "fs";
+import { tmpdir } from "os";
+import { join, dirname } from "path";
+import { fileURLToPath } from "url";
+
+const REPO_ROOT = join(dirname(fileURLToPath(import.meta.url)), "..");
+const DATA_DIR = join(REPO_ROOT, "src/source/data");
+const TERMINUS_REPO = "pantheon-systems/terminus";
+
+// Terminus commands.json mirrors Symfony Console's `list --format=json`
+// output verbatim — no transform needed, so drift here means the source
+// file changed shape, not a bug in this script.
+interface CommandsJson {
+  application: { name: string; version: string };
+  commands: unknown[];
+}
+
+function ghToken(): string | undefined {
+  if (process.env.GITHUB_TOKEN) return process.env.GITHUB_TOKEN;
+  try {
+    return execFileSync("gh", ["auth", "token"], { encoding: "utf8" }).trim();
+  } catch {
+    return undefined;
+  }
+}
+
+async function githubFetch(url: string): Promise<Response> {
+  const token = ghToken();
+  const headers: Record<string, string> = {
+    Accept: "application/vnd.github+json",
+    "User-Agent": "pantheon-systems-documentation-update-terminus-data",
+  };
+  if (token) headers.Authorization = `Bearer ${token}`;
+  const res = await fetch(url, { headers });
+  if (!res.ok) {
+    throw new Error(`GitHub API request failed: ${res.status} ${res.statusText} — ${url}`);
+  }
+  return res;
+}
+
+async function fetchAllReleases(): Promise<unknown[]> {
+  const releases: unknown[] = [];
+  let page = 1;
+  for (;;) {
+    const res = await githubFetch(
+      `https://api.github.com/repos/${TERMINUS_REPO}/releases?per_page=100&page=${page}`
+    );
+    const batch = (await res.json()) as unknown[];
+    if (batch.length === 0) break;
+    releases.push(...batch);
+    if (batch.length < 100) break;
+    page += 1;
+  }
+  return releases;
+}
+
+async function fetchLatestRelease(): Promise<{
+  tag_name: string;
+  assets: Array<{ name: string; browser_download_url: string }>;
+}> {
+  const res = await githubFetch(
+    `https://api.github.com/repos/${TERMINUS_REPO}/releases/latest`
+  );
+  return res.json() as Promise<{
+    tag_name: string;
+    assets: Array<{ name: string; browser_download_url: string }>;
+  }>;
+}
+
+async function downloadPhar(url: string, destPath: string): Promise<void> {
+  const res = await fetch(url);
+  if (!res.ok) {
+    throw new Error(`Failed to download terminus.phar: ${res.status} ${res.statusText}`);
+  }
+  const buffer = Buffer.from(await res.arrayBuffer());
+  writeFileSync(destPath, buffer);
+}
+
+function runTerminusListJson(pharPath: string): CommandsJson {
+  const out = execFileSync("php", [pharPath, "list", "--format=json"], {
+    encoding: "utf8",
+    maxBuffer: 32 * 1024 * 1024,
+  });
+  return JSON.parse(out) as CommandsJson;
+}
+
+function writeJson(relPath: string, data: unknown): void {
+  const fullPath = join(DATA_DIR, relPath);
+  writeFileSync(fullPath, JSON.stringify(data, null, 2) + "\n");
+  console.error(`Wrote ${relPath}`);
+}
+
+async function updateCommands(): Promise<void> {
+  const latest = await fetchLatestRelease();
+  const pharAsset = latest.assets.find((a) => a.name === "terminus.phar");
+  if (!pharAsset) {
+    throw new Error(`No terminus.phar asset found on release ${latest.tag_name}`);
+  }
+
+  const tmpDir = mkdtempSync(join(tmpdir(), "terminus-phar-"));
+  const pharPath = join(tmpDir, "terminus.phar");
+  try {
+    await downloadPhar(pharAsset.browser_download_url, pharPath);
+    const commandsJson = runTerminusListJson(pharPath);
+    writeJson("commands.json", commandsJson);
+    console.error(
+      `commands.json: ${commandsJson.application.name} ${commandsJson.application.version} (${commandsJson.commands.length} commands)`
+    );
+  } finally {
+    rmSync(tmpDir, { recursive: true, force: true });
+  }
+}
+
+async function updateReleases(): Promise<void> {
+  const releases = await fetchAllReleases();
+  writeJson("terminusReleases.json", releases);
+  console.error(`terminusReleases.json: ${releases.length} releases`);
+}
+
+async function main() {
+  await updateCommands();
+  await updateReleases();
+}
+
+main().catch((err) => {
+  console.error(err instanceof Error ? err.message : err);
+  process.exit(1);
+});