diff --git a/data_only_viz/iphone_usb_source.py b/data_only_viz/iphone_usb_source.py
index 4351d60..0cecdb8 100644
--- a/data_only_viz/iphone_usb_source.py
+++ b/data_only_viz/iphone_usb_source.py
@@ -114,6 +114,9 @@ class IphoneUSBSource:
         return self._opened
 
     def _run(self, sock) -> None:
+        if self.state is not None:
+            with self.state.lock():
+                self.state.mirror_2d = self._mirror
         while not self._stop.is_set():
             if sock is None:                      # no connection yet (startup or post-drop)
                 sock = self._reconnect()
diff --git a/data_only_viz/renderer.py b/data_only_viz/renderer.py
index 3e623ef..ca2906c 100644
--- a/data_only_viz/renderer.py
+++ b/data_only_viz/renderer.py
@@ -327,6 +327,9 @@ class MetalRenderer(NSObject):
 
         buf = self._skel_cpu_buf
         segs = 0
+        # Mirror overlays in X to match the (already mirrored) iPhone video
+        # background. Display-only: gesture data is untouched.
+        mirror = bool(getattr(s, "mirror_2d", False))
 
         def push(A, B, conf, pid):
             """Empile un segment (2 verts) dans le buffer CPU prealloque."""
@@ -335,6 +338,8 @@ class MetalRenderer(NSObject):
                 return False
             ax = A.x * 2.0 - 1.0; ay = 1.0 - A.y * 2.0
             bx = B.x * 2.0 - 1.0; by = 1.0 - B.y * 2.0
+            if mirror:
+                ax = -ax; bx = -bx
             i = segs * 10
             buf[i+0] = ax; buf[i+1] = ay; buf[i+2] = float(A.z); buf[i+3] = conf; buf[i+4] = float(pid)
             buf[i+5] = bx; buf[i+6] = by; buf[i+7] = float(B.z); buf[i+8] = conf; buf[i+9] = float(pid)
@@ -348,6 +353,8 @@ class MetalRenderer(NSObject):
                 return False
             cax = ax * 2.0 - 1.0; cay = 1.0 - ay * 2.0
             cbx = bx * 2.0 - 1.0; cby = 1.0 - by * 2.0
+            if mirror:
+                cax = -cax; cbx = -cbx
             i = segs * 10
             buf[i+0] = cax; buf[i+1] = cay; buf[i+2] = 0.0
             buf[i+3] = conf; buf[i+4] = float(pid)
diff --git a/data_only_viz/state.py b/data_only_viz/state.py
index d2f730b..0cb6bfa 100644
--- a/data_only_viz/state.py
+++ b/data_only_viz/state.py
@@ -151,6 +151,8 @@ class State:
     persons_arkit_2d_valid: dict = field(default_factory=dict)
     arkit_joint_names: list = field(default_factory=list)
     arkit_parents: list = field(default_factory=list)
+    # iPhone video is mirrored (CONCERT_MIRROR); renderer mirrors overlays to match.
+    mirror_2d: bool = False
 
     # ---- LiDAR / ICP mesh fusion (Task 8 - 2026-05-14) ----
     # Set by the LidarTCPReader poller; consumed by FusionWorker.run_once.