refactor: apply code quality suggestions from task-6-mobile-fab review

Three suggestions from the code review applied:

1. Extract _createSessionInput() factory to eliminate five-line
   duplication between showNewSessionInput and showFabSessionInput.
   Both functions now call the shared factory. Updated 4 existing
   tests to check _createSessionInput's body; added 7 new tests
   covering factory behavior and factory usage in each consumer.

2. Fix .new-session-fab:focus-visible outline color from var(--accent)
   to var(--bg) — the FAB background is already var(--accent), so
   using the same color for the outline created zero contrast.
   Added 1 new test to guard this going forward.

3. Add early-return guard in showFabSessionInput against duplicate
   overlays: if (document.querySelector('.fab-input-overlay')) return;
   Prevents a second overlay being created if called programmatically
   while one is already open. Added 1 new test.

532 tests pass (9 new tests added, 523 unchanged).

muxplex/frontend/app.js

@@ -1292,13 +1292,24 @@ function updateSessionPill(sessions) {
  * On blur: delayed cleanup (150ms) to allow click handlers.
  * @param {HTMLElement} btn - The button element to replace temporarily.
  */
-function showNewSessionInput(btn) {
+/**
+ * Create a new session name input element with shared base configuration.
+ * Used by both showNewSessionInput (inline) and showFabSessionInput (overlay)
+ * to avoid duplicating the five setup properties.
+ * @returns {HTMLInputElement}
+ */
+function _createSessionInput() {
   const input = document.createElement('input');
   input.type = 'text';
   input.className = 'new-session-input';
   input.placeholder = 'Session name\u2026';
   input.autocomplete = 'off';
   input.spellcheck = false;
+  return input;
+}
+
+function showNewSessionInput(btn) {
+  const input = _createSessionInput();
 
   function cleanup() {
     if (input.parentNode) input.parentNode.removeChild(input);
@@ -1331,17 +1342,14 @@ function showNewSessionInput(btn) {
  * visible on mobile regardless of body/view overflow:hidden constraints.
  */
 function showFabSessionInput() {
+  if (document.querySelector('.fab-input-overlay')) return;
+
   const fab = $('new-session-fab');
 
   const overlay = document.createElement('div');
   overlay.className = 'fab-input-overlay';
 
-  const input = document.createElement('input');
-  input.type = 'text';
-  input.className = 'new-session-input';
-  input.placeholder = 'Session name\u2026';
-  input.autocomplete = 'off';
-  input.spellcheck = false;
+  const input = _createSessionInput();
 
   overlay.appendChild(input);
 

muxplex/frontend/style.css

@@ -1234,7 +1234,7 @@ body {
 }
 
 .new-session-fab:focus-visible {
-  outline: 2px solid var(--accent);
+  outline: 2px solid var(--bg);
   outline-offset: 2px;
 }
 

muxplex/tests/test_frontend_css.py

@@ -1,6 +1,7 @@
 """Tests for frontend/style.css — design tokens and dark theme."""
 
 import pathlib
+import re
 
 CSS_PATH = pathlib.Path(__file__).parent.parent / "frontend" / "style.css"
 
@@ -1606,3 +1607,19 @@ def test_css_fab_active_transform() -> None:
     assert ".new-session-fab:active" in css, (
         "Missing .new-session-fab:active rule in style.css"
     )
+
+
+def test_css_fab_focus_visible_outline_not_accent() -> None:
+    """.new-session-fab:focus-visible outline must not use var(--accent) — same color as FAB background gives zero contrast."""
+    css = read_css()
+    match = re.search(r"\.new-session-fab:focus-visible\s*\{([^}]*)\}", css)
+    assert match, "Missing .new-session-fab:focus-visible rule in style.css"
+    body = match.group(1)
+    assert "outline" in body, ".new-session-fab:focus-visible must have an outline property"
+    # The FAB background IS var(--accent), so using the same color as outline gives zero visible ring.
+    # Must use var(--bg) or var(--text) for sufficient contrast.
+    assert "var(--accent)" not in body, (
+        ".new-session-fab:focus-visible outline must not use var(--accent) — "
+        "the FAB background is already var(--accent), so the outline would be invisible. "
+        "Use var(--bg) or var(--text) for contrast."
+    )

muxplex/tests/test_frontend_js.py

@@ -1543,58 +1543,58 @@ def test_create_new_session_function_exists() -> None:
 
 
 def test_show_new_session_input_creates_input_with_class() -> None:
-    """showNewSessionInput must create an input element with class 'new-session-input'."""
+    """Input setup must set class 'new-session-input' (via _createSessionInput factory)."""
     match = re.search(
-        r"function showNewSessionInput\s*\(\w+\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        r"function _createSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
         _JS,
         re.DOTALL,
     )
-    assert match, "showNewSessionInput function not found"
+    assert match, "_createSessionInput function not found"
     body = match.group(1)
     assert "new-session-input" in body, (
-        "showNewSessionInput must create an input with class 'new-session-input'"
+        "_createSessionInput must set input.className = 'new-session-input'"
     )
 
 
 def test_show_new_session_input_sets_placeholder() -> None:
-    """showNewSessionInput must set placeholder to 'Session name…'."""
+    """Input setup must set placeholder containing 'Session name' (via _createSessionInput factory)."""
     match = re.search(
-        r"function showNewSessionInput\s*\(\w+\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        r"function _createSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
         _JS,
         re.DOTALL,
     )
-    assert match, "showNewSessionInput function not found"
+    assert match, "_createSessionInput function not found"
     body = match.group(1)
     assert "Session name" in body, (
-        "showNewSessionInput must set placeholder containing 'Session name'"
+        "_createSessionInput must set placeholder containing 'Session name'"
     )
 
 
 def test_show_new_session_input_disables_autocomplete() -> None:
-    """showNewSessionInput must set autocomplete off on the input."""
+    """Input setup must set autocomplete off (via _createSessionInput factory)."""
     match = re.search(
-        r"function showNewSessionInput\s*\(\w+\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        r"function _createSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
         _JS,
         re.DOTALL,
     )
-    assert match, "showNewSessionInput function not found"
+    assert match, "_createSessionInput function not found"
     body = match.group(1)
     assert "autocomplete" in body.lower() and "off" in body.lower(), (
-        "showNewSessionInput must set autocomplete off"
+        "_createSessionInput must set autocomplete off"
     )
 
 
 def test_show_new_session_input_disables_spellcheck() -> None:
-    """showNewSessionInput must set spellcheck false on the input."""
+    """Input setup must set spellcheck false (via _createSessionInput factory)."""
     match = re.search(
-        r"function showNewSessionInput\s*\(\w+\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        r"function _createSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
         _JS,
         re.DOTALL,
     )
-    assert match, "showNewSessionInput function not found"
+    assert match, "_createSessionInput function not found"
     body = match.group(1)
     assert "spellcheck" in body.lower() and "false" in body.lower(), (
-        "showNewSessionInput must set spellcheck false"
+        "_createSessionInput must set spellcheck false"
     )
 
 
@@ -1928,3 +1928,120 @@ def test_js_fab_click_calls_show_fab_session_input() -> None:
         "bindStaticEventListeners must call showFabSessionInput for FAB click — "
         "the old showNewSessionInput(fab) inserts into body which is clipped by overflow:hidden"
     )
+
+
+def test_js_show_fab_session_input_guards_against_duplicate_overlay() -> None:
+    """showFabSessionInput must guard against creating a second overlay if one already exists."""
+    match = re.search(
+        r"function showFabSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nfunction |\nasync function |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "showFabSessionInput function not found"
+    body = match.group(1)
+    assert "fab-input-overlay" in body, (
+        "showFabSessionInput must check for an existing .fab-input-overlay before creating another — "
+        "prevents duplicate overlays if called programmatically while one is already open"
+    )
+    # Guard must be present: querySelector('.fab-input-overlay') with early return
+    assert "querySelector" in body and "return" in body, (
+        "showFabSessionInput must guard with document.querySelector('.fab-input-overlay') return; "
+        "at the top to prevent duplicate overlays"
+    )
+
+
+# ============================================================
+# _createSessionInput factory (quality refactor — suggestion 1)
+# ============================================================
+
+
+def test_js_create_session_input_factory_exists() -> None:
+    """_createSessionInput factory must exist in app.js to eliminate input setup duplication."""
+    assert "function _createSessionInput" in _JS, (
+        "_createSessionInput must be defined in app.js — "
+        "shared factory eliminates duplicated input setup in showNewSessionInput and showFabSessionInput"
+    )
+
+
+def test_js_create_session_input_factory_sets_class() -> None:
+    """_createSessionInput must return an input with class 'new-session-input'."""
+    match = re.search(
+        r"function _createSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "_createSessionInput function not found"
+    body = match.group(1)
+    assert "new-session-input" in body, (
+        "_createSessionInput must set input.className = 'new-session-input'"
+    )
+
+
+def test_js_create_session_input_factory_sets_placeholder() -> None:
+    """_createSessionInput must set placeholder containing 'Session name'."""
+    match = re.search(
+        r"function _createSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "_createSessionInput function not found"
+    body = match.group(1)
+    assert "Session name" in body, (
+        "_createSessionInput must set placeholder containing 'Session name'"
+    )
+
+
+def test_js_create_session_input_factory_disables_autocomplete() -> None:
+    """_createSessionInput must set autocomplete off."""
+    match = re.search(
+        r"function _createSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "_createSessionInput function not found"
+    body = match.group(1)
+    assert "autocomplete" in body.lower() and "off" in body.lower(), (
+        "_createSessionInput must set autocomplete off"
+    )
+
+
+def test_js_create_session_input_factory_disables_spellcheck() -> None:
+    """_createSessionInput must set spellcheck false."""
+    match = re.search(
+        r"function _createSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "_createSessionInput function not found"
+    body = match.group(1)
+    assert "spellcheck" in body.lower() and "false" in body.lower(), (
+        "_createSessionInput must set spellcheck false"
+    )
+
+
+def test_js_show_new_session_input_uses_factory() -> None:
+    """showNewSessionInput must call _createSessionInput() instead of duplicating input setup."""
+    match = re.search(
+        r"function showNewSessionInput\s*\(\w+\)\s*\{(.*?)(?=\nasync function |\nfunction |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "showNewSessionInput function not found"
+    body = match.group(1)
+    assert "_createSessionInput" in body, (
+        "showNewSessionInput must call _createSessionInput() to create the input element"
+    )
+
+
+def test_js_show_fab_session_input_uses_factory() -> None:
+    """showFabSessionInput must call _createSessionInput() instead of duplicating input setup."""
+    match = re.search(
+        r"function showFabSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nfunction |\nasync function |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "showFabSessionInput function not found"
+    body = match.group(1)
+    assert "_createSessionInput" in body, (
+        "showFabSessionInput must call _createSessionInput() to create the input element"
+    )