fix: handle undefined pathname in URL builder

biome.json

@@ -1,5 +1,5 @@
 {
-	"$schema": "https://biomejs.dev/schemas/2.4.6/schema.json",
+	"$schema": "https://biomejs.dev/schemas/2.4.11/schema.json",
 	"formatter": {
 		"enabled": true,
 		"indentStyle": "tab"

package.json

@@ -63,7 +63,7 @@
     "@babel/preset-typescript": "^7.28.5",
     "@babel/runtime": "^7.28.4",
     "@babel/runtime-corejs3": "^7.28.4",
-    "@biomejs/biome": "2.4.6",
+    "@biomejs/biome": "^2.4.11",
     "@rspack/cli": "^1.7.0",
     "@rspack/core": "^1.7.0",
     "@types/ace": "^0.0.52",

src/test/tester.js

@@ -2,6 +2,7 @@ import { runAceCompatibilityTests } from "./ace.test";
 import { runCodeMirrorTests } from "./editor.tests";
 import { runExecutorTests } from "./exec.tests";
 import { runSanityTests } from "./sanity.tests";
+import { runUrlTests } from "./url.tests";
 
 export async function runAllTests() {
 	const terminal = acode.require("terminal");
@@ -20,6 +21,7 @@ export async function runAllTests() {
 		await runCodeMirrorTests(write);
 		await runAceCompatibilityTests(write);
 		await runExecutorTests(write);
+		await runUrlTests(write);
 
 		write("\x1b[36m\x1b[1mTests completed!\x1b[0m\n");
 	} catch (error) {

src/test/url.tests.js

@@ -0,0 +1,136 @@
+import Url from "../utils/Url";
+import { TestRunner } from "./tester";
+
+export async function runUrlTests(writeOutput) {
+	const runner = new TestRunner("URL / SAF URI Tests");
+
+	runner.test(
+		"Android external storage: join active location + index.html",
+		(test) => {
+			const folderUrl =
+				"content://com.android.externalstorage.documents/tree/primary%3ATesthtml";
+			const activeLocation =
+				"content://com.android.externalstorage.documents/tree/primary%3ATesthtml::primary:Testhtml/Styles/";
+			const expectedJoined =
+				"content://com.android.externalstorage.documents/tree/primary%3ATesthtml::primary:Testhtml/Styles/index.html";
+
+			const joined = Url.join(activeLocation, "index.html");
+
+			test.assertEqual(
+				joined,
+				expectedJoined,
+				"Joined URL should match expected Android SAF file URI",
+			);
+			test.assert(
+				!Url.areSame(folderUrl, joined),
+				"Folder URL and joined file URL should not be considered same",
+			);
+		},
+	);
+
+	runner.test("Termux SAF: join active location + index.html", (test) => {
+		const folderUrl =
+			"content://com.termux.documents/tree/%2Fdata%2Fdata%2Fcom.termux%2Ffiles%2Fhome%2Facode-site-ui";
+		const activeLocation =
+			"content://com.termux.documents/tree/%2Fdata%2Fdata%2Fcom.termux%2Ffiles%2Fhome%2Facode-site-ui::/data/data/com.termux/files/home/acode-site-ui/";
+		const expectedJoined =
+			"content://com.termux.documents/tree/%2Fdata%2Fdata%2Fcom.termux%2Ffiles%2Fhome%2Facode-site-ui::/data/data/com.termux/files/home/acode-site-ui/index.html";
+
+		const joined = Url.join(activeLocation, "index.html");
+
+		test.assertEqual(
+			joined,
+			expectedJoined,
+			"Joined URL should match expected Termux SAF file URI",
+		);
+		test.assert(
+			!Url.areSame(folderUrl, joined),
+			"Folder URL and joined file URL should not be considered same",
+		);
+	});
+
+	runner.test(
+		"Acode terminal SAF: join active location + index.html",
+		(test) => {
+			const folderUrl =
+				"content://com.foxdebug.acode.documents/tree/%2Fdata%2Fuser%2F0%2Fcom.foxdebug.acode%2Ffiles%2Fpublic";
+			const activeLocation =
+				"content://com.foxdebug.acode.documents/tree/%2Fdata%2Fuser%2F0%2Fcom.foxdebug.acode%2Ffiles%2Fpublic::/data/user/0/com.foxdebug.acode/files/public/";
+			const expectedJoined =
+				"content://com.foxdebug.acode.documents/tree/%2Fdata%2Fuser%2F0%2Fcom.foxdebug.acode%2Ffiles%2Fpublic::/data/user/0/com.foxdebug.acode/files/public/index.html";
+
+			const joined = Url.join(activeLocation, "index.html");
+
+			test.assertEqual(
+				joined,
+				expectedJoined,
+				"Joined URL should match expected Acode Terminal SAF file URI",
+			);
+			test.assert(
+				!Url.areSame(folderUrl, joined),
+				"Folder URL and joined file URL should not be considered same",
+			);
+		},
+	);
+
+	runner.test(
+		"Android SAF folder URL should match with trailing slash",
+		(test) => {
+			const a =
+				"content://com.android.externalstorage.documents/tree/primary%3ATesthtml/";
+			const b =
+				"content://com.android.externalstorage.documents/tree/primary%3ATesthtml";
+
+			test.assert(
+				Url.areSame(a, b),
+				"Android folder URLs differing only by trailing slash should be same",
+			);
+		},
+	);
+
+	runner.test(
+		"Termux SAF folder URL should match with trailing slash",
+		(test) => {
+			const a =
+				"content://com.termux.documents/tree/%2Fdata%2Fdata%2Fcom.termux%2Ffiles%2Fhome%2Facode-site-ui/";
+			const b =
+				"content://com.termux.documents/tree/%2Fdata%2Fdata%2Fcom.termux%2Ffiles%2Fhome%2Facode-site-ui";
+
+			test.assert(
+				Url.areSame(a, b),
+				"Termux folder URLs differing only by trailing slash should be same",
+			);
+		},
+	);
+
+	runner.test(
+		"Acode terminal SAF folder URL should match with trailing slash",
+		(test) => {
+			const a =
+				"content://com.foxdebug.acode.documents/tree/%2Fdata%2Fuser%2F0%2Fcom.foxdebug.acode%2Ffiles%2Fpublic/";
+			const b =
+				"content://com.foxdebug.acode.documents/tree/%2Fdata%2Fuser%2F0%2Fcom.foxdebug.acode%2Ffiles%2Fpublic";
+
+			test.assert(
+				Url.areSame(a, b),
+				"Acode terminal folder URLs differing only by trailing slash should be same",
+			);
+		},
+	);
+
+	runner.test("join should handle leading slash segment", (test) => {
+		const activeLocation =
+			"content://com.android.externalstorage.documents/tree/primary%3ATesthtml::primary:Testhtml/Styles/";
+		const expectedJoined =
+			"content://com.android.externalstorage.documents/tree/primary%3ATesthtml::primary:Testhtml/Styles/index.html";
+
+		const joined = Url.join(activeLocation, "/index.html");
+		test.assertEqual(
+			joined,
+			expectedJoined,
+			"Leading slash in joined segment should be normalized",
+		);
+	});
+
+	return await runner.run(writeOutput);
+}

src/utils/Url.js

@@ -76,7 +76,7 @@ export default {
 				if (pathnames[1].startsWith("/")) pathnames[1] = pathnames[1].slice(1);
 				const contentUri = Uri.parse(url);
 				let [root, pathname] = contentUri.docId.split(":");
-				const newDocId = path.join(pathname, ...pathnames.slice(1));
+				let newDocId = path.join(pathname, ...pathnames.slice(1));
 				if (/^content:\/\/com.termux/.test(url)) {
 					const rootCondition = root.endsWith("/");
 					const newDocIdCondition = newDocId.startsWith("/");
@@ -87,6 +87,21 @@ export default {
 					}
 					return `${contentUri.rootUri}::${root}${newDocId}${query}`;
 				}
+
+				// if pathname is undefined, meaning a docId/volume (e.g :primary:)
+				// has not been detected, so no newDocId's ":" will be added.
+				if (!pathname) {
+					// Ensure proper path separator between root and newDocId
+					let separator = "";
+					if (root.endsWith("/") && newDocId.startsWith("/")) {
+						// Both have separator, strip one from newDocId
+						newDocId = newDocId.slice(1);
+					} else if (!root.endsWith("/") && !newDocId.startsWith("/")) {
+						// Neither has separator, add one
+						separator = "/";
+					}
+					return `${contentUri.rootUri}::${root}${separator}${newDocId}${query}`;
+				}
 				return `${contentUri.rootUri}::${root}:${newDocId}${query}`;
 			} catch (error) {
 				return null;