chore: code quality sweep 2026-05-04 / 2026-05-05

General code-quality and robustness pass across the plugin: thread-
safety on IPC state, resource-disposal cleanups, input validation,
defensive null-checks and a few small UX glitches. Compliance docs
(THIRD_PARTY_NOTICES, PRIVACY, COPYRIGHT) refreshed to v1.0.3.

Highlights
- ExtraChat IPC state synchronised across threads
- ChatLogWindow autocomplete no longer leaks the unmanaged
  ImGuiListClipper allocation
- ChatLogWindow + Popout style stack stays balanced when config
  toggles mid-frame
- Retention sweep and privacy cleanup wait for the actual filter
  pass instead of the fire-and-forget Task that started it
- Configuration.LatestVersion bumped to 13 to match the active
  migration path
- GameFunctions placeholder buffer guarded against oversized
  replacement names
- TellTarget.IsSet, ResolveTempInputChannel, InputPreview, IconUtil,
  Lender, Payloads, ExtraPayload all hardened against null / empty /
  EOF / cycle inputs
- FontManager Lodestone download stays in scope for a follow-up
  (timeout + lazy init pending)
- AutoTranslate replaced the msvcrt.dll memcmp P/Invoke with a
  managed Span comparison
- Privacy cleanup worker thread marked IsBackground = true
- Database cleanup now removes both legacy files in one click
- Tell-target name redacted in the verbose debug log

Compliance
- THIRD_PARTY_NOTICES: last-reviewed bumped to v1.0.3, Pidgin 3.5.1,
  SQLitePCLRaw.lib.e_sqlite3 3.50.3 listed as direct dependency with
  CVE-2025-6965 / CVE-2025-7709 rationale
- PRIVACY: last-reviewed bumped to v1.0.3, BetterTTV trigger wording
  clarified (list fetch at startup vs. on-demand image fetch)
- COPYRIGHT: upstream attribution range widened

Build: 0 warnings, 0 errors. No behavioural changes that would alter
existing user configuration or stored chat history.

HellionChat/Util/ExtraPayload.cs

@@ -25,6 +25,8 @@ public class ColorPayload
                 return payload;
             case 0xE9:
                 var param = stream.ReadByte();
+                if (param == -1)
+                    throw new ArgumentException("Encountered premature end of input (unexpected EOF).", nameof(stream));
                 var globalValue = (uint) GlobalParametersCache.GetValue(param - 2);
                 payload.Enabled = true;
                 payload.UnshiftedColor = globalValue;