diff --git a/muxplex/tests/test_frontend_js.py b/muxplex/tests/test_frontend_js.py
index 571d869..8b3849f 100644
--- a/muxplex/tests/test_frontend_js.py
+++ b/muxplex/tests/test_frontend_js.py
@@ -4820,7 +4820,7 @@ def test_terminal_js_weblinks_addon_has_try_catch() -> None:
     var_match = re.search(r"var WebLinksAddon", body)
     assert var_match, "var WebLinksAddon assignment not found"
     weblinks_idx = var_match.start()
-    nearby = body[max(0, weblinks_idx - 100):weblinks_idx + 300]
+    nearby = body[max(0, weblinks_idx - 100) : weblinks_idx + 300]
     assert "try" in nearby and "catch" in nearby, (
         "WebLinksAddon loading must be wrapped in try/catch"
     )
@@ -4837,7 +4837,7 @@ def test_terminal_js_search_addon_has_try_catch() -> None:
     body = match.group(1)
     assert "SearchAddon" in body, "createTerminal must reference SearchAddon"
     search_idx = body.index("SearchAddon")
-    nearby = body[max(0, search_idx - 200):search_idx + 300]
+    nearby = body[max(0, search_idx - 200) : search_idx + 300]
     assert "try" in nearby and "catch" in nearby, (
         "SearchAddon loading must be wrapped in try/catch"
     )
@@ -4869,7 +4869,7 @@ def test_terminal_js_image_addon_has_try_catch() -> None:
     body = match.group(1)
     assert "ImageAddon" in body, "createTerminal must reference ImageAddon"
     image_idx = body.index("ImageAddon")
-    nearby = body[max(0, image_idx - 200):image_idx + 300]
+    nearby = body[max(0, image_idx - 200) : image_idx + 300]
     assert "try" in nearby and "catch" in nearby, (
         "ImageAddon loading must be wrapped in try/catch"
     )
@@ -4902,3 +4902,105 @@ def test_terminal_js_open_terminal_has_ghostty_ready_guard() -> None:
     assert "_ghosttyReady" in body, (
         "openTerminal must have a _ghosttyReady guard before creating the terminal"
     )
+
+
+# ============================================================
+# Muxterm protocol tests (task-13: remove cache/ttyd, verify muxterm)
+# ============================================================
+
+
+def test_terminal_js_no_ttyd_prefix_encoding() -> None:
+    """terminal.js must not contain ttyd-style prefix bytes 0x30 or 0x31.
+
+    The old ttyd protocol used 0x30 (input) and 0x31 (resize) prefix bytes
+    before each WebSocket frame.  The muxterm protocol uses plain binary
+    for terminal I/O and JSON text frames for control messages, so these
+    prefix constants must not appear anywhere in terminal.js.
+    """
+    assert "0x30" not in _TERMINAL_JS, (
+        "terminal.js must not contain 0x30 (ttyd input prefix) — "
+        "muxterm uses raw binary for terminal I/O"
+    )
+    assert "0x31" not in _TERMINAL_JS, (
+        "terminal.js must not contain 0x31 (ttyd resize prefix) — "
+        "muxterm uses JSON text frames for resize"
+    )
+
+
+def test_terminal_js_no_terminal_cache() -> None:
+    """terminal.js must not contain _terminalCache or _cacheOrder.
+
+    The old ttyd approach cached multiple Terminal instances so switching
+    sessions was instant.  The muxterm architecture uses a single persistent
+    WebSocket with attach/detach commands, so there is no terminal cache.
+    """
+    assert "_terminalCache" not in _TERMINAL_JS, (
+        "terminal.js must not contain _terminalCache — "
+        "muxterm uses a single terminal with attach/detach, no caching"
+    )
+    assert "_cacheOrder" not in _TERMINAL_JS, (
+        "terminal.js must not contain _cacheOrder — "
+        "terminal caching was removed in the muxterm rewrite"
+    )
+
+
+def test_terminal_js_uses_json_attach() -> None:
+    """terminal.js must use JSON attach messages to switch sessions.
+
+    The muxterm protocol attaches to a session by sending a JSON text
+    frame: { attach: "sessionName" }.  This replaces the old approach
+    of opening a new WebSocket per session.
+    """
+    assert "attach:" in _TERMINAL_JS, (
+        "terminal.js must contain 'attach:' — "
+        "muxterm uses JSON { attach: sessionName } to switch sessions"
+    )
+
+
+def test_terminal_js_uses_json_resize() -> None:
+    """terminal.js must send resize events as JSON with cols and rows.
+
+    The muxterm protocol sends resize as a JSON text frame:
+    { resize: { cols: N, rows: N } }.  This replaces the old ttyd
+    0x31 prefix + binary encoding.
+    """
+    assert "resize" in _TERMINAL_JS, (
+        "terminal.js must contain 'resize' — "
+        "muxterm uses JSON { resize: { cols, rows } } for resize events"
+    )
+    assert "cols" in _TERMINAL_JS, (
+        "terminal.js must contain 'cols' — resize JSON must include cols"
+    )
+    assert "rows" in _TERMINAL_JS, (
+        "terminal.js must contain 'rows' — resize JSON must include rows"
+    )
+
+
+def test_terminal_js_fetches_terminal_token() -> None:
+    """terminal.js must fetch /api/terminal-token before connecting.
+
+    The muxterm protocol requires a short-lived token from the API
+    server before opening the WebSocket to the muxterm port.  This
+    ensures authentication is handled by the main API.
+    """
+    assert "/api/terminal-token" in _TERMINAL_JS, (
+        "terminal.js must fetch /api/terminal-token — "
+        "muxterm requires a token before WebSocket connection"
+    )
+
+
+def test_terminal_js_connects_to_muxterm_port_directly() -> None:
+    """connectWebSocket URL must target muxterm port directly, not /terminal/ws.
+
+    The old ttyd proxy routed through /terminal/ws on the main server.
+    The muxterm protocol connects directly to the muxterm port:
+    ws://host:muxtermPort/ws?token=...
+    """
+    assert "/terminal/ws" not in _TERMINAL_JS, (
+        "terminal.js must not connect to /terminal/ws — "
+        "muxterm connects directly to ws://host:muxtermPort/ws"
+    )
+    assert "_muxtermPort" in _TERMINAL_JS, (
+        "terminal.js must reference _muxtermPort — "
+        "WebSocket connects directly to the muxterm port"
+    )