feat(video-section): enumerate cameras and render dropdown

Empty labels fall back to 'Camera N'; duplicate labels are
disambiguated with ' (1)', ' (2)' suffixes by enumeration order.
'No cameras detected' subline appears when enumeration is empty.

packages/web/src/components/modals/settingsPanels/VideoSection.tsx

@@ -1,4 +1,5 @@
-import { useEffect, useRef, useState } from 'react';
+import { useEffect, useMemo, useRef, useState } from 'react';
+import { useVoiceStore } from '../../../stores/voiceStore';
 import { isElectron, getElectronAPI } from '../../../platform/platform';
 
 type PermissionState = 'unknown' | 'probing' | 'granted' | 'initial-denied' | 'hard-blocked';
@@ -22,10 +23,59 @@ function getHardBlockedCopy(): string {
   return 'Camera permission was denied. Reset it in your browser/Chromium prompt and try again.';
 }
 
+/**
+ * Build a deviceId → display-label map applying the spec's rules:
+ * - Empty `label` falls back to `"Camera N"` using enumeration index.
+ * - Duplicate non-empty labels get `" (1)"`, `" (2)"` suffixes by enumeration order.
+ *   Single occurrences stay unsuffixed.
+ */
+function buildDisplayLabels(devices: MediaDeviceInfo[]): Map<string, string> {
+  const counts = new Map<string, number>();
+  for (const d of devices) {
+    if (d.label) counts.set(d.label, (counts.get(d.label) ?? 0) + 1);
+  }
+  const seen = new Map<string, number>();
+  const labels = new Map<string, string>();
+  devices.forEach((d, i) => {
+    if (!d.label) {
+      labels.set(d.deviceId, `Camera ${i + 1}`);
+      return;
+    }
+    const total = counts.get(d.label) ?? 1;
+    if (total <= 1) {
+      labels.set(d.deviceId, d.label);
+      return;
+    }
+    const used = (seen.get(d.label) ?? 0) + 1;
+    seen.set(d.label, used);
+    labels.set(d.deviceId, `${d.label} (${used})`);
+  });
+  return labels;
+}
+
 export function VideoSection() {
+  const cameraDeviceId = useVoiceStore((s) => s.cameraDeviceId);
+  const setCameraDeviceId = useVoiceStore((s) => s.setCameraDeviceId);
+
   const [permState, setPermState] = useState<PermissionState>('unknown');
+  const [devices, setDevices] = useState<MediaDeviceInfo[]>([]);
+  const [listOpen, setListOpen] = useState(false);
   // Tracks mount state so async probe handlers don't write to state after unmount.
   const mountedRef = useRef(true);
+  // Anchor for the dropdown's click-outside-to-close behaviour.
+  const dropdownRef = useRef<HTMLDivElement>(null);
+
+  // Close the dropdown when the user clicks outside it.
+  useEffect(() => {
+    if (!listOpen) return;
+    const onMouseDown = (e: MouseEvent) => {
+      if (dropdownRef.current && !dropdownRef.current.contains(e.target as Node)) {
+        setListOpen(false);
+      }
+    };
+    document.addEventListener('mousedown', onMouseDown);
+    return () => document.removeEventListener('mousedown', onMouseDown);
+  }, [listOpen]);
 
   // Run the probe once on mount.
   useEffect(() => {
@@ -49,6 +99,42 @@ export function VideoSection() {
     };
   }, []);
 
+  // Enumerate cameras when permission is granted; refresh on devicechange.
+  useEffect(() => {
+    if (permState !== 'granted') return;
+
+    let cancelled = false;
+    const enumerate = async () => {
+      try {
+        const all = await navigator.mediaDevices.enumerateDevices();
+        if (cancelled) return;
+        const seen = new Set<string>();
+        const cams: MediaDeviceInfo[] = [];
+        for (const d of all) {
+          if (d.kind !== 'videoinput') continue;
+          if (seen.has(d.deviceId)) continue;
+          seen.add(d.deviceId);
+          cams.push(d);
+        }
+        setDevices(cams);
+      } catch {
+        if (!cancelled) setDevices([]);
+      }
+    };
+
+    enumerate();
+    const onChange = () => {
+      enumerate();
+    };
+    navigator.mediaDevices.addEventListener('devicechange', onChange);
+    return () => {
+      cancelled = true;
+      navigator.mediaDevices.removeEventListener('devicechange', onChange);
+    };
+  }, [permState]);
+
+  const displayLabels = useMemo(() => buildDisplayLabels(devices), [devices]);
+
   const handleTryAgain = async () => {
     setPermState('probing');
     try {
@@ -100,15 +186,94 @@ export function VideoSection() {
     );
   }
 
-  // permState === 'granted' — main UI added in T9–T12.
+  // permState === 'granted'
+  const selectedLabel =
+    cameraDeviceId === null
+      ? 'Auto (system default)'
+      : displayLabels.get(cameraDeviceId) ?? 'Auto (system default)';
+
+  const handleSelect = (id: string | null) => {
+    setCameraDeviceId(id);
+    setListOpen(false);
+  };
+
   return (
     <div>
       <div className="text-[11px] font-semibold text-txt-tertiary uppercase tracking-wider mb-1.5">
         Video
       </div>
-      <div className="rounded-lg bg-white/[0.03] border border-white/[0.04] p-3.5 text-sm text-txt-tertiary italic">
+      <div className="rounded-lg bg-white/[0.03] border border-white/[0.04] p-3.5">
-        (UI under construction — Task 9 adds dropdown, T10–T11 add preview, T12 adds lifecycle.)
+        <div className="text-[13px] font-medium text-txt-primary mb-1.5">Camera</div>
+        <div ref={dropdownRef}>
+          <button
+            type="button"
+            onClick={() => setListOpen((v) => !v)}
+            className="w-full px-3 py-2 flex items-center justify-between rounded-md bg-surface-base hover:bg-interactive-hover transition-colors"
+          >
+            <span className="text-[13px] text-txt-primary truncate text-left">{selectedLabel}</span>
+            <svg
+              width="16"
+              height="16"
+              viewBox="0 0 24 24"
+              fill="currentColor"
+              className={`text-txt-tertiary flex-shrink-0 ml-2 transition-transform ${listOpen ? 'rotate-90' : ''}`}
+            >
+              <path d="M10 6L8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z" />
+            </svg>
+          </button>
+          {listOpen && (
+            <div className="mt-1 rounded-md bg-surface-base border border-border-hard py-1">
+              <DropdownItem
+                label="Auto (system default)"
+                active={cameraDeviceId === null}
+                onClick={() => handleSelect(null)}
+              />
+              {devices.map((d) => (
+                <DropdownItem
+                  key={d.deviceId}
+                  label={displayLabels.get(d.deviceId) ?? d.deviceId}
+                  active={cameraDeviceId === d.deviceId}
+                  onClick={() => handleSelect(d.deviceId)}
+                />
+              ))}
+            </div>
+          )}
+        </div>
+        {devices.length === 0 && (
+          <div className="text-xs text-txt-tertiary mt-1">No cameras detected.</div>
+        )}
       </div>
     </div>
   );
 }
+
+interface DropdownItemProps {
+  label: string;
+  active: boolean;
+  onClick: () => void;
+}
+
+function DropdownItem({ label, active, onClick }: DropdownItemProps) {
+  return (
+    <button
+      type="button"
+      onClick={onClick}
+      className={`w-full px-3 py-2 text-left text-[13px] hover:bg-interactive-hover transition-colors flex items-center gap-2 ${
+        active ? 'text-txt-primary' : 'text-txt-secondary'
+      }`}
+    >
+      {active && (
+        <svg
+          width="16"
+          height="16"
+          viewBox="0 0 24 24"
+          fill="currentColor"
+          className="text-accent-primary flex-shrink-0"
+        >
+          <path d="M9 16.17L4.83 12l-1.42 1.41L9 19 21 7l-1.41-1.41z" />
+        </svg>
+      )}
+      <span className={`truncate ${active ? '' : 'pl-6'}`}>{label}</span>
+    </button>
+  );
+}