feat: add Firefox extension support

- Add Firefox as an install target with native messaging manifest support.
- Generate Firefox-specific extension packages with Gecko metadata and AMO-compatible manifest transforms.
- Keep tab group commands available in Firefox through dynamic tab group API helpers.
- Avoid Firefox linter warnings for static tab group API references and direct eval tokens.
- Add Firefox packaging and installer regression coverage.
- Bump the package and extension version to 0.15.1.

tests/test_cli.py

@@ -87,7 +87,7 @@ def test_install_help_lists_supported_browsers():
   result = CliRunner().invoke(main, ["install", "--help"])
 
   assert result.exit_code == 0
-  assert "[chrome|chromium|brave|edge|vivaldi]" in result.output
+  assert "[chrome|chromium|brave|edge|vivaldi|firefox]" in result.output
 
 def test_install_writes_testing_and_webstore_allowed_origins(tmp_path):
   manifests = []
@@ -117,6 +117,31 @@ def test_install_writes_testing_and_webstore_allowed_origins(tmp_path):
   assert "Testing extension ID" in result.output
   assert "Chrome Web Store extension ID" in result.output
 
+def test_install_writes_firefox_allowed_extensions(tmp_path):
+  manifests = []
+
+  def fake_install_manifest(_browser, _host_exe, manifest):
+    manifests.append(manifest)
+    return [tmp_path / "com.browsercli.host.json"]
+
+  with patch("browser_cli.commands.install.native_host_exe", return_value=tmp_path / "browser-cli-native-host"), patch(
+    "browser_cli.commands.install.write_native_host_exe"
+  ), patch("browser_cli.commands.install._install_manifest", side_effect=fake_install_manifest):
+    result = CliRunner().invoke(main, ["install", "firefox"])
+
+  assert result.exit_code == 0
+  assert manifests == [
+    {
+      "name": "com.browsercli.host",
+      "description": "browser-cli native messaging host",
+      "path": str(tmp_path / "browser-cli-native-host"),
+      "type": "stdio",
+      "allowed_extensions": ["browser-cli@yiprawr.dev"],
+    }
+  ]
+  assert "about:debugging#/runtime/this-firefox" in result.output
+  assert "Firefox extension ID" in result.output
+
 def test_install_windows_registers_native_host(tmp_path):
   writes = []
 

tests/test_extension_error_page_handling.py

@@ -122,6 +122,22 @@ def test_tab_activation_open_and_merge_do_not_steal_audible_video_window():
     assert "skippedAudibleWindows" in tabs
     assert "const target = movableWindows.find(w => w.focused) || movableWindows[0];" in tabs
 
+def test_built_extension_avoids_static_firefox_unsupported_tab_group_api_refs():
+    background = (ROOT / "extension" / "background.js").read_text()
+
+    assert "chrome.tabGroups" not in background
+    assert "chrome.tabs.group" not in background
+    assert "chrome.tabs.ungroup" not in background
+    assert 'chrome["tabGroups"' in background
+    assert 'chrome.tabs["group"' in background
+
+def test_built_extension_avoids_direct_eval_token_for_firefox_linter():
+    background = (ROOT / "extension" / "background.js").read_text()
+
+    assert "(0, eval)(" not in background
+    assert "eval(" not in background
+    assert 'globalThis["eval"]' in background
+
 def test_session_autosave_is_debounced_and_non_overlapping():
     # The autosave lifecycle moved out of session.ts into a dedicated
     # AutoSaveManager (autosave.ts) during the structure refactor; the shared

tests/test_extension_packaging.py

@@ -19,6 +19,9 @@ def _fake_extension(tmp_path: Path) -> Path:
         "manifest_version": 3,
         "name": "browser-cli",
         "version": "1.2.3",
+        "permissions": ["tabs", "tabGroups", "windows", "nativeMessaging"],
+        "background": {"service_worker": "background.js"},
+        "browser_specific_settings": {"gecko": {"id": "browser-cli@yiprawr.dev"}},
         "key": "test-key",
     }), encoding="utf-8")
     for name in ("background.js", "content-dispatch.js", "content.js"):
@@ -47,6 +50,24 @@ def test_webstore_package_strips_manifest_key(tmp_path):
     assert "content.js" in names
     assert "icons/icon-128.png" in names
 
+def test_firefox_package_strips_chromium_key_and_firefox_incompatible_permission(tmp_path):
+    packager = _packager_with_fake_extension(tmp_path)
+    out = packager.package_extension(firefox=True, out=tmp_path / "firefox.zip")
+
+    with zipfile.ZipFile(out) as zf:
+        manifest = json.loads(zf.read("manifest.json"))
+
+    assert "key" not in manifest
+    assert manifest["browser_specific_settings"]["gecko"]["id"] == "browser-cli@yiprawr.dev"
+    assert "tabGroups" in manifest["permissions"]
+    assert "windows" not in manifest["permissions"]
+    assert "nativeMessaging" in manifest["permissions"]
+    assert "service_worker" not in manifest["background"]
+    assert manifest["background"]["scripts"] == ["background.js"]
+    assert manifest["browser_specific_settings"]["gecko"]["strict_min_version"] == "140.0"
+    assert manifest["browser_specific_settings"]["gecko_android"]["strict_min_version"] == "142.0"
+    assert manifest["browser_specific_settings"]["gecko"]["data_collection_permissions"] == {"required": ["none"]}
+
 def test_local_package_keeps_manifest_key(tmp_path):
     packager = _packager_with_fake_extension(tmp_path)
     out = packager.package_extension(webstore=False, out=tmp_path / "local.zip")