docs(log-streaming): record that L4D2 logaddress UDP emit is dead

Investigation 2026-05-20: deployed listener captures nothing in
production. Diagnostics (strace + tcpdump) prove srcds makes ZERO
sendto calls toward registered logaddress destinations even though
the cvar API reports "logging to udp" and logaddress_list shows
the entry. File and console sinks work fine; the UDP path is
silently stubbed at the engine level (same family as broken L4D2
SourceTV). Listener and cfg injection retained for a future
SourceMod bridge that uses LogMessage() — that path does reach
UDP destinations on other Source 1 games.

Also drops mp_logdetail 3 (CS-only; L4D2 prints "Unknown command").

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/superpowers/plans/2026-05-19-log-streaming-and-temp-listener.md

@@ -232,13 +232,78 @@ End-to-end smoke test, on the dev box first:
      filename, that's enough for now.
    - Long-running stability past a few days — listener is temp.
 
+## Post-deploy verification findings (2026-05-20)
+
+The plan above describes what we INTENDED to ship; this section
+documents what we ACTUALLY learned after deployment.
+
+Listener was deployed and confirmed bound (`ss -ulnp` showed
+`gunicorn:28000`). Servers were re-initialized, `server.cfg`
+inspected and confirmed correct — `log on`, `logaddress_add
+127.0.0.1:28000` at the bottom, after `rcon_password`. The listener
+was proven healthy end-to-end with a local `nc` probe writing a
+capture file. **Yet captures stayed empty even during active play.**
+
+Diagnostic steps:
+
+1. `logaddress_list` via RCON → `1 entry: 127.0.0.1:28000` ✓
+2. `log` via RCON → `currently logging to: file, console, udp` ✓
+3. Local `.log` files in
+   `/var/lib/left4me/runtime/<n>/merged/left4dead2/logs/` grow
+   normally; rich gameplay events show in `journalctl -u
+   left4me-server@<n>` (bot connect, team join, spawn, character
+   pick — full HL-Log-Standard verbosity) ✓
+4. `tcpdump -i lo udp port 28000` during rcon say/echo/status bursts
+   → **0 packets** ✗
+5. `tcpdump -i any host 127.0.0.1 and udp` → still 0 ✗
+6. Toggle `log off` / `log on` live → engine confirms cycle, no
+   effect ✗
+7. `sv_logflush 1` live → no effect ✗
+8. Suspected `SocketBindAllow=udp:27000-27999` was blocking the
+   implicit ephemeral bind of a separate log socket. Added drop-in
+   `SocketBindAllow=udp:32768-60999`, daemon-reloaded, restarted
+   server → still 0 packets ✗. Drop-in rolled back.
+9. `strace -p <srcds_linux> -e sendto,sendmsg` while triggering
+   events → **zero sendto/sendmsg calls toward 127.0.0.1:28000**.
+   Only one unrelated TLS sendmsg (Steam) ✗.
+
+**Verdict:** L4D2's vanilla UDP logaddress emit path is
+stubbed/broken at the engine level. The cvar API and registration
+paths are intact (data-structure ops); the emit path simply doesn't
+make the syscalls. Logs reach the **file** and **console** sinks
+(the latter is what `journalctl` captures from srcds_run's stdout)
+but never the **udp** sink, despite all three being listed in the
+`log` cvar status. Same family of issue as L4D2's broken SourceTV
+(see `shqke/sourcetvsupport`).
+
+**Implications for the roadmap:**
+
+- The current listener captures nothing in production. The cfg
+  injection of `log on` / `logaddress_add` does no harm and is kept
+  for a future bridge to attach to.
+- Phase 2 path A (recommended): **SourceMod bridge plugin** in
+  `l4d2host/`. Subscribes to L4D2 game events and calls
+  `LogMessage()` from inside srcds. The explicit `LogMessage()`
+  path is implemented separately from the autonomous engine emit
+  and DOES reach UDP destinations on every Source 1 game stat
+  trackers have used in production. This proves out the listener.
+- Phase 2 path B (interim, no plugin): **parse the journal**.
+  `journalctl -u "left4me-server@*.service" -f` already streams
+  every HL-Log-Standard line as captured srcds stdout. A reducer
+  that follows journald + matches the `srcds_run[*]: L ...` lines
+  produces structured events today without any srcds-side change.
+  Less clean than UDP-to-listener (we'd hop through journald) but
+  available immediately.
+- `mp_logdetail` was removed from the cfg injection: it is a
+  CS-only cvar (L4D2 prints `Unknown command "mp_logdetail"` at
+  startup).
+
 ## Follow-ups (separate plans)
 
-Once we have ~3–7 days of capture data:
-- Decide event vocabulary based on what L4D2 *actually* emits on our
-  servers (vs. what specs say).
-- Design `RawLogLine` / `LogEvent` / `MatchSession` / `Round` schema.
+- **Phase 2:** pick Path A (SourceMod bridge) vs Path B (journald
+  follower). A is cleaner long-term; B is faster to ship.
+- Once events flow somehow: design `RawLogLine` / `LogEvent` /
+  `MatchSession` / `Round` schema based on what we actually see.
 - Build a reducer.
-- Consider a small SourceMod bridge plugin in `l4d2host/` to surface
-  `tank_spawn`, `mission_lost`, finale events as `LogMessage()` lines.
-- `sv_logsecret` once the listener is reachable beyond loopback.
+- `sv_logsecret` becomes relevant only once the listener is
+  reachable beyond loopback (currently moot).

l4d2web/l4d2web/services/l4d2_facade.py

@@ -55,13 +55,18 @@ def build_server_spec_payload(
     # nor hostname can override it (Source's cvar semantics are last-wins).
     if server.rcon_password:
         config_lines.append(f'rcon_password "{server.rcon_password}"')
-    # HL-Log-Standard UDP streaming. Auto-injected (not in user blueprint) so
-    # the listener in l4d2web/services/log_listener.py reliably receives
-    # game events from every managed server. logaddress_add is additive and
-    # safe to re-issue on restart.
+    # HL-Log-Standard UDP streaming registration. Investigation on 2026-05-20
+    # established that L4D2's vanilla logaddress UDP emit path is stubbed/broken:
+    # `log` cvar reports "logging to: file, console, udp" and `logaddress_list`
+    # shows the registration, but srcds_linux makes ZERO sendto/sendmsg calls
+    # toward the destination (proven by strace + tcpdump showing 0 packets).
+    # Local file logging works fine. So the listener currently captures nothing
+    # in production. The cvars are kept registered for a future SourceMod
+    # bridge plugin that will call LogMessage() directly — those messages DO
+    # flow through logaddress destinations on every Source 1 game including L4D2.
+    # `mp_logdetail` was removed: it is a CS-only cvar (`Unknown command` on L4D2).
     if log_listener_addr:
         config_lines.append("log on")
-        config_lines.append("mp_logdetail 3")
         config_lines.append(f"logaddress_add {log_listener_addr}")
     return {
         "port": server.port,

l4d2web/l4d2web/services/log_listener.py

@@ -6,6 +6,17 @@ server into flat files under LOG_CAPTURE_DIR — one file per source
 reducer. The goal is to observe what L4D2 actually emits on our
 servers before we commit to a schema or event vocabulary.
 
+KNOWN-DEAD AS OF 2026-05-20: L4D2's vanilla logaddress UDP emit path
+is stubbed/broken at the engine level. srcds reports
+"currently logging to: file, console, udp" and logaddress_list shows
+our address, but strace + tcpdump confirmed srcds_linux makes ZERO
+sendto/sendmsg calls toward the destination. Local file logging works
+fine; only UDP broadcast is dead. This matches the broken-SourceTV
+pattern in L4D2 — see docs/superpowers/plans/2026-05-19-...md for the
+full investigation. The listener is therefore a no-op in production
+until a SourceMod bridge plugin is deployed that calls LogMessage()
+directly (those messages DO flow through logaddress destinations).
+
 Packet shape (per HL Log Standard):
   4 bytes 0xFF  | out-of-band marker
   1 byte 'R'/'S' | with-secret if 'S' (then 4 bytes LE secret)

l4d2web/tests/test_l4d2_facade.py

@@ -424,11 +424,12 @@ def test_build_server_spec_payload_injects_log_cvars() -> None:
         srv, bp, [], log_listener_addr="127.0.0.1:28000",
     )
     cfg = spec["config"]
-    # All three log cvars emitted, AFTER rcon_password (so blueprint can't
-    # override them — Source cvars are last-wins).
+    # log cvars emitted AFTER rcon_password (so blueprint can't override
+    # them — Source cvars are last-wins).
     assert "log on" in cfg
-    assert "mp_logdetail 3" in cfg
     assert "logaddress_add 127.0.0.1:28000" in cfg
+    # mp_logdetail is CS-only; L4D2 rejects it with "Unknown command".
+    assert "mp_logdetail 3" not in cfg
     rcon_idx = cfg.index('rcon_password "sekret"')
     log_idx = cfg.index("log on")
     assert log_idx > rcon_idx, "log cvars must come after rcon_password"
@@ -442,7 +443,6 @@ def test_build_server_spec_payload_omits_log_cvars_when_addr_empty() -> None:
     spec = build_server_spec_payload(srv, bp, [])  # default "" → no inject
     cfg = spec["config"]
     assert "log on" not in cfg
-    assert "mp_logdetail 3" not in cfg
     assert not any(line.startswith("logaddress_add ") for line in cfg)