diff --git a/crates/punktfunk-host/src/gamestream/rtsp.rs b/crates/punktfunk-host/src/gamestream/rtsp.rs
index 5f155178..8bf85dea 100644
--- a/crates/punktfunk-host/src/gamestream/rtsp.rs
+++ b/crates/punktfunk-host/src/gamestream/rtsp.rs
@@ -450,6 +450,25 @@ fn stream_config(map: &HashMap<String, String>) -> Option<StreamConfig> {
         );
         hdr = false;
     }
+    // Second half of the same live gate: the process-wide HDR-capture latch. The colour-mode probe
+    // above only says the monitor is in BT.2100 RIGHT NOW — it says nothing about whether the
+    // portal will actually hand us the 10-bit PQ formats. Once a `want_hdr` negotiation has failed
+    // (the monitor left HDR mode between probe and negotiation, NVIDIA EGL not listing LINEAR for
+    // XR30, a pre-50 Mutter), `pf_capture::open_portal_monitor` permanently drops the HDR OFFER and
+    // captures SDR. Without this check we'd keep telling the client HDR while capturing and
+    // encoding SDR: it renders an SDR picture through PQ — washed out, wrong gamut, no error
+    // anywhere — and because the latch is sticky until host restart, every reconnect repeats it.
+    // Consulted here rather than folded into `host_hdr_capable` for the same reason as the probe
+    // above: that fn is the STATIC serverinfo capability, and this is a live per-session fact.
+    #[cfg(target_os = "linux")]
+    if hdr && pf_capture::hdr_capture_failed() {
+        tracing::warn!(
+            "client requested HDR and a monitor is in BT.2100 (HDR) colour mode, but an earlier \
+             HDR capture negotiation on this host failed — the capturer offers SDR only for the \
+             rest of the process lifetime, so streaming 8-bit SDR (restart the host to retry HDR)"
+        );
+        hdr = false;
+    }
     // The client's requested CSC (moonlight-common-c SdpGenerator.c: `encoderCscMode =
     // (colorspace << 1) | fullRange` — colorspace 0=Rec601, 1=Rec709, 2=Rec2020). Moonlight
     // renderers configure their YUV→RGB from this REQUESTED value (not the bitstream VUI), so a
diff --git a/crates/punktfunk-host/src/native/handshake.rs b/crates/punktfunk-host/src/native/handshake.rs
index 067d7146..2a9da219 100644
--- a/crates/punktfunk-host/src/native/handshake.rs
+++ b/crates/punktfunk-host/src/native/handshake.rs
@@ -267,6 +267,12 @@ pub(super) async fn negotiate(
     // *monitor* streams only — the GameStream portal-mirror path uses that; see
     // `gamestream::host_hdr_capable`), so a Linux native session honestly stays 8-bit SDR even
     // though `can_encode_10bit` now probes true on a Main10-capable GPU.
+    //
+    // That `false` is also why this plane needs no equivalent of the GameStream path's
+    // `pf_capture::hdr_capture_failed()` check (rtsp.rs): that latch is a fact about the PORTAL
+    // capturer's HDR offer, and the native plane captures a virtual output instead — it never
+    // reaches the portal path, and on Linux it never negotiates 10-bit at all. Revisit both halves
+    // together if Mutter ever gains HDR for RecordVirtual streams.
     let capture_supports_hdr = crate::capture::capturer_supports_hdr();
     // The GPU probe may open a tiny encoder on first use, so run it off the reactor like the
     // 4:4:4 probe below (blocking probes → spawn_blocking), short-circuited behind the cheap