From fed05c44486ef7fccb009aba513d384117cc192e Mon Sep 17 00:00:00 2001
From: Alex Vanderveen <alex@technicallycomputers.ca>
Date: Fri, 21 Aug 2026 17:56:06 -0400
Subject: [PATCH] lan: report MOTK datagrams no handler claimed
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The host logged 'LAN rx MOTK5 MODOK' every 2 s with no seat ever going ready,
and the same silence blocks MOTK5 SEATMOVE/SWAPREQ — so players cannot change
seats either. Both live in one dispatch chain of strncmp(buf, "...\n", N)
tests, and the receipt trace at the top cannot distinguish 'arrived and was
handled' from 'arrived and every handler declined': it prints the first line
and stops at '\n' OR '\0', so a datagram missing its trailing newline (or
carrying CRLF, or truncated) renders identically while every match fails.

Add an end-of-chain trace, rate-limited to 3 s, printing the byte count and
the escaped payload, so the wire format is observed instead of assumed. KICK/
ERR now continues like every other handler so it is not misreported.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UoSNLFj7kvarYHEV9PCZpV
---
 runtime/src/main.cpp | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/runtime/src/main.cpp b/runtime/src/main.cpp
index 948b5509..ceccccd1 100644
--- a/runtime/src/main.cpp
+++ b/runtime/src/main.cpp
@@ -11099,6 +11099,41 @@ namespace {
                 g_lnch_lan_endpoint.clear();
                 g_lnch_remote_lan_state = {};
                 ae_np_lan_udp_close();
+                continue;
+            }
+
+            /* UNCLAIMED: every handler above `continue`s when it takes the
+             * message, so reaching here means no handler matched. The receipt
+             * trace at the top of this loop cannot show this — it prints the
+             * first line and stops at '\n' OR '\0', so a datagram that is
+             * missing its trailing newline (or carries CRLF, or is truncated)
+             * looks IDENTICAL there while every strncmp against "...\n" below
+             * declines it. That is invisible-by-construction: the host logs
+             * 'LAN rx MOTK5 MODOK' forever, no seat ever goes ready, seat
+             * moves never apply, and the guest resends once a second.
+             * Print the exact bytes so the wire format is not a guess. */
+            if (std::strncmp(buf, "MOTK", 4) == 0) {
+                static uint32_t s_last_unclaimed_ms = 0;
+                const uint32_t nowm = (uint32_t)SDL_GetTicks64();
+                if (nowm - s_last_unclaimed_ms > 3000u) {
+                    s_last_unclaimed_ms = nowm;
+                    char shown[64] = {0};
+                    int k = 0;
+                    for (int i = 0; i < n && k < (int)sizeof(shown) - 5; ++i) {
+                        const unsigned char c = (unsigned char)buf[i];
+                        if (c == '\n')      { shown[k++] = '\\'; shown[k++] = 'n'; }
+                        else if (c == '\r') { shown[k++] = '\\'; shown[k++] = 'r'; }
+                        else if (c < 32)    { shown[k++] = '?'; }
+                        else                { shown[k++] = (char)c; }
+                    }
+                    std::fprintf(stderr,
+                        "psxrecomp: LAN mods: UNCLAIMED datagram (%d bytes, "
+                        "hosting=%d): \"%s\" — no handler matched; if this is "
+                        "MODOK/SEATMOVE the peer's wire format disagrees with "
+                        "this build\n",
+                        n, g_lnch_hosting_lan ? 1 : 0, shown);
+                    std::fflush(stderr);
+                }
             }
         }
     }