Add Zotero.ML for Firefox's machine-learning runtime

The runtime runs models in a separate, memory-gated inference process
using the native ONNX Runtime and llama.cpp libraries Firefox ships. It
reads its model configuration, runtime configuration, and model-host
policy from Remote Settings, which our build omits, so loading the empty
module throws on the first collection lookup. Supply those collections
directly instead.

Allow only the two backends that use those native libraries, onnx-native
and llama.cpp. The rest either load a WebAssembly runtime from a Remote
Settings attachment, whose record lookup also needs the Translations
actors our build omits (onnx, wllama, and the best-* backends that fall
back to them), or aren't local at all (openai).

chrome/content/zotero/xpcom/ml.js

@@ -0,0 +1,144 @@
+/*
+    ***** BEGIN LICENSE BLOCK *****
+
+    Copyright © 2026 Corporation for Digital Scholarship
+                     Vienna, Virginia, USA
+                     https://www.zotero.org
+
+    This file is part of Zotero.
+
+    Zotero is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Zotero is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with Zotero.  If not, see <http://www.gnu.org/licenses/>.
+
+    ***** END LICENSE BLOCK *****
+*/
+
+/**
+ * Zotero.ML -- access to Firefox's machine-learning runtime
+ * (toolkit/components/ml), which runs models in a separate, memory-gated
+ * inference process using the native ONNX Runtime and llama.cpp libraries
+ * Firefox ships.
+ *
+ * Engines are created through createEngine(), which supplies the runtime
+ * configuration Zotero's build requires. Callers pass the model and task.
+ */
+Zotero.ML = new function () {
+	// Hosts models may be loaded from, in the runtime's allow-list format.
+	// Local files cover models Zotero downloads itself; the runtime always
+	// allows chrome://, resource://, and localhost.
+	const ALLOWED_MODEL_HOSTS = [
+		{ filter: 'ALLOW', urlPrefix: 'file://' },
+		{ filter: 'ALLOW', urlPrefix: 'https://huggingface.co/' }
+	];
+
+	// The backends that run on the native libraries Firefox ships. The rest
+	// either load a WebAssembly runtime from a Remote Settings attachment
+	// ('onnx' and 'wllama', plus the 'best-*' backends that fall back to them)
+	// or aren't local at all ('openai').
+	const NATIVE_BACKENDS = ['onnx-native', 'llama.cpp'];
+
+	var _configured = false;
+
+	/**
+	 * The runtime reads its model configuration, runtime configuration, and
+	 * model-host policy from Remote Settings, which Zotero's build omits.
+	 * Supply those collections here: the model and runtime collections return
+	 * no records, which the runtime handles by falling back to the
+	 * configuration passed to createEngine(), and the host policy comes from
+	 * ALLOWED_MODEL_HOSTS. Without this, loading the empty Remote Settings
+	 * module throws when the runtime first looks up a collection.
+	 */
+	function _configureRuntime() {
+		if (_configured) {
+			return;
+		}
+		let { MLEngineParent } = ChromeUtils.importESModule(
+			"resource://gre/actors/MLEngineParent.sys.mjs"
+		);
+		let client = records => ({
+			get: async () => records,
+			on() {},
+			off() {}
+		});
+		MLEngineParent.mockRemoteSettings({
+			'ml-onnx-runtime': client([]),
+			'ml-inference-options': client([]),
+			'ml-model-allow-deny-list': client(ALLOWED_MODEL_HOSTS)
+		});
+		_configured = true;
+	}
+
+	/**
+	 * Whether the runtime can run models, which requires an enabled runtime
+	 * and enough physical memory for the inference process
+	 *
+	 * @return {Boolean}
+	 */
+	this.isAvailable = function () {
+		if (!Services.prefs.getBoolPref('browser.ml.enable', false)) {
+			return false;
+		}
+		if (!Services.prefs.getBoolPref('browser.ml.checkForMemory', true)) {
+			return true;
+		}
+		let minimum = Services.prefs.getIntPref('browser.ml.minimumPhysicalMemory', 3);
+		let utils = Cc["@mozilla.org/ml-utils;1"].getService(Ci.nsIMLUtils);
+		return utils.totalPhysicalMemory >= minimum * 1024 * 1024 * 1024;
+	};
+
+	/**
+	 * Create an inference engine.
+	 *
+	 * The model is downloaded on first use and cached by the runtime. Model
+	 * hosts other than Mozilla's and localhost are rejected unless the
+	 * MOZ_ALLOW_EXTERNAL_ML_HUB environment variable is set.
+	 *
+	 * @param {Object} options - Pipeline options for the runtime, including
+	 *     `taskName`, `modelId`, and `backend` (see NATIVE_BACKENDS)
+	 * @param {Function} [onProgress] - Called with the runtime's download and
+	 *     initialization progress
+	 * @return {Promise<Object>} - The engine, with run() and terminate()
+	 */
+	this.createEngine = async function (options, onProgress) {
+		if (!this.isAvailable()) {
+			throw new Error("Machine-learning runtime is not available");
+		}
+		if (!NATIVE_BACKENDS.includes(options.backend)) {
+			throw new Error(`Backend '${options.backend}' requires a runtime this build `
+				+ `doesn't include -- use one of: ${NATIVE_BACKENDS.join(', ')}`);
+		}
+		_configureRuntime();
+		let { createEngine } = ChromeUtils.importESModule(
+			"chrome://global/content/ml/EngineProcess.sys.mjs"
+		);
+		Zotero.debug(`ML: creating ${options.taskName} engine for `
+			+ `${options.modelId} on ${options.backend}`);
+		return createEngine(options, onProgress);
+	};
+
+	/**
+	 * Shut down the inference process, releasing the memory held by any
+	 * loaded models
+	 *
+	 * @return {Promise}
+	 */
+	this.shutdown = async function () {
+		if (!_configured) {
+			return;
+		}
+		let { EngineProcess } = ChromeUtils.importESModule(
+			"chrome://global/content/ml/EngineProcess.sys.mjs"
+		);
+		await EngineProcess.destroyMLEngine();
+	};
+};

chrome/content/zotero/zotero.mjs

@@ -112,6 +112,7 @@ const xpcomFilesLocal = [
 	'locale',
 	'locateManager',
 	'mime',
+	'ml',
 	'notifier',
 	'undoHistory',
 	'fileHandlers',