diff --git a/clients/probe/src/main.rs b/clients/probe/src/main.rs
index 7bf17ff..99c47cf 100644
--- a/clients/probe/src/main.rs
+++ b/clients/probe/src/main.rs
@@ -412,7 +412,7 @@ async fn session(args: Args) -> Result<()> {
     io::write_msg(
         &mut send,
         &Hello {
-            abi_version: punktfunk_core::ABI_VERSION,
+            abi_version: punktfunk_core::WIRE_VERSION,
             mode: args.mode,
             compositor: args.compositor,
             gamepad: args.gamepad,
diff --git a/crates/punktfunk-core/src/client.rs b/crates/punktfunk-core/src/client.rs
index 8b43fd8..91bf531 100644
--- a/crates/punktfunk-core/src/client.rs
+++ b/crates/punktfunk-core/src/client.rs
@@ -876,7 +876,7 @@ async fn worker_main(args: WorkerArgs) {
         io::write_msg(
             &mut send,
             &Hello {
-                abi_version: crate::ABI_VERSION,
+                abi_version: crate::WIRE_VERSION,
                 mode,
                 compositor,
                 gamepad,
diff --git a/crates/punktfunk-core/src/lib.rs b/crates/punktfunk-core/src/lib.rs
index ec991dc..cd77ffe 100644
--- a/crates/punktfunk-core/src/lib.rs
+++ b/crates/punktfunk-core/src/lib.rs
@@ -54,3 +54,11 @@ pub use stats::Stats;
 /// v3: added `punktfunk_wake_on_lan` (Wake-on-LAN magic packet; the host's wake MAC(s) reach
 /// clients out-of-band via the mDNS `mac` TXT record, so no connection is required to wake).
 pub const ABI_VERSION: u32 = 3;
+
+/// The punktfunk/1 **wire** version — what `Hello`/`Welcome` carry and hosts equality-check.
+/// Deliberately its own constant: [`ABI_VERSION`] tracks the embeddable **C surface**
+/// (functions a client links), which can grow without changing a single wire byte — v3's
+/// `punktfunk_wake_on_lan` is client-local, and riding the C-ABI bump onto the wire locked
+/// every new client out of every deployed host ("ABI mismatch: client 3 host 2", observed
+/// live). Bump this ONLY when the handshake/planes actually change incompatibly.
+pub const WIRE_VERSION: u32 = 2;
diff --git a/crates/punktfunk-host/src/punktfunk1.rs b/crates/punktfunk-host/src/punktfunk1.rs
index df1a8dc..b0b593f 100644
--- a/crates/punktfunk-host/src/punktfunk1.rs
+++ b/crates/punktfunk-host/src/punktfunk1.rs
@@ -585,10 +585,10 @@ async fn serve_session(
         // the `handshake` future re-decodes for the real session — a few dozen bytes, negligible.
         let gate_hello = Hello::decode(&first).map_err(|e| anyhow!("Hello decode: {e:?}"))?;
         anyhow::ensure!(
-            gate_hello.abi_version == punktfunk_core::ABI_VERSION,
-            "ABI mismatch: client {} host {}",
+            gate_hello.abi_version == punktfunk_core::WIRE_VERSION,
+            "wire version mismatch: client {} host {}",
             gate_hello.abi_version,
-            punktfunk_core::ABI_VERSION
+            punktfunk_core::WIRE_VERSION
         );
         let fp = endpoint::peer_fingerprint(&conn);
         let known = fp
@@ -654,10 +654,10 @@ async fn serve_session(
     let handshake = async {
         let hello = Hello::decode(&first).map_err(|e| anyhow!("Hello decode: {e:?}"))?;
         anyhow::ensure!(
-            hello.abi_version == punktfunk_core::ABI_VERSION,
-            "ABI mismatch: client {} host {}",
+            hello.abi_version == punktfunk_core::WIRE_VERSION,
+            "wire version mismatch: client {} host {}",
             hello.abi_version,
-            punktfunk_core::ABI_VERSION
+            punktfunk_core::WIRE_VERSION
         );
         // The pairing gate (require_pairing → paired? else park for delegated approval) ran above,
         // before this future, so a client reaching here is paired (or the host is `--open`).
@@ -805,7 +805,7 @@ async fn serve_session(
         let mut key = [0u8; 16];
         rand::thread_rng().fill_bytes(&mut key);
         let welcome = Welcome {
-            abi_version: punktfunk_core::ABI_VERSION,
+            abi_version: punktfunk_core::WIRE_VERSION,
             udp_port,
             mode: hello.mode,
             // The post-GameStream point of punktfunk/1: Leopard GF(2¹⁶) FEC + real encryption.
diff --git a/include/punktfunk_core.h b/include/punktfunk_core.h
index 7f1b76f..4cbfc90 100644
--- a/include/punktfunk_core.h
+++ b/include/punktfunk_core.h
@@ -21,6 +21,14 @@
 // clients out-of-band via the mDNS `mac` TXT record, so no connection is required to wake).
 #define ABI_VERSION 3
 
+// The punktfunk/1 **wire** version — what `Hello`/`Welcome` carry and hosts equality-check.
+// Deliberately its own constant: [`ABI_VERSION`] tracks the embeddable **C surface**
+// (functions a client links), which can grow without changing a single wire byte — v3's
+// `punktfunk_wake_on_lan` is client-local, and riding the C-ABI bump onto the wire locked
+// every new client out of every deployed host ("ABI mismatch: client 3 host 2", observed
+// live). Bump this ONLY when the handshake/planes actually change incompatibly.
+#define WIRE_VERSION 2
+
 // `PunktfunkHidOutput::kind` — lightbar RGB (`r`/`g`/`b` valid).
 #define PUNKTFUNK_HIDOUT_LED 1