Add FFDec docs/tools and server-browser fixes

Add comprehensive FFDec walkthrough and short patch docs for safely adding a Multiplayer item to MainMenu.swf, plus helper scripts to extract the vanilla SWF and restore it (tools/extract_ba2.py, tools/restore-vanilla-mainmenu.ps1). Update exported MainMenu.as with a warning comment and remove an outdated exported PATCH markdown. Patch binary Interface/MainMenu.swf (updated).

Hardening fixes in the plugin: include GFx headers, avoid leaving the PrismaUI overlay focused after menu changes, only call OnBrowserHidden when the browser was actually visible, and add IsMainMenuOnMainPanel() so WatchMainMenuState ignores MainMenu when not on the MAIN_STATE. Ensure events are only dispatched when the browser is valid & visible (CanDispatchToBrowser) and make Scaleform UI hide the browser immediately during transitions. These changes prevent the overlay from staying focused during Settings transitions and stop JS events from being sent to a hidden/invalid view.

tools/extract_ba2.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""Extract a single file from a Fallout 4 BA2 (BTDX) archive."""
+
+from __future__ import annotations
+
+import argparse
+import struct
+import zlib
+from pathlib import Path
+
+
+def read_name(data: bytes, offset: int) -> tuple[str, int]:
+    length = struct.unpack_from("<H", data, offset)[0]
+    start = offset + 2
+    name = data[start : start + length].decode("utf-8", errors="replace")
+    return name, start + length
+
+
+def extract_file(archive: Path, target: str, output: Path) -> None:
+    data = archive.read_bytes()
+    if data[:4] != b"BTDX":
+        raise SystemExit(f"Not a BA2 archive: {archive}")
+
+    version = struct.unpack_from("<I", data, 4)[0]
+    if version not in (1, 7, 8):
+        raise SystemExit(f"Unsupported BA2 version {version}")
+
+    archive_type = data[8:12].decode("ascii", errors="replace")
+    if archive_type != "GNRL":
+        raise SystemExit(f"Unsupported archive type {archive_type!r} (only GNRL supported)")
+
+    num_files = struct.unpack_from("<I", data, 12)[0]
+    name_table = struct.unpack_from("<Q", data, 16)[0]
+    file_table = 24
+
+    target_norm = target.replace("/", "\\").lower()
+    name_cursor = name_table
+    for i in range(num_files):
+        name, name_cursor = read_name(data, name_cursor)
+        entry_offset = file_table + i * 36
+        (
+            _name_hash,
+            _ext,
+            _dir_hash,
+            _flags,
+            file_offset,
+            packed_size,
+            unpacked_size,
+            _unk,
+        ) = struct.unpack_from("<I4sIIQIII", data, entry_offset)
+
+        if name.lower() != target_norm:
+            continue
+
+        if packed_size and unpacked_size and packed_size != unpacked_size:
+            payload = zlib.decompress(data[file_offset : file_offset + packed_size])
+        else:
+            size = unpacked_size or packed_size
+            payload = data[file_offset : file_offset + size]
+
+        output.parent.mkdir(parents=True, exist_ok=True)
+        output.write_bytes(payload)
+        print(f"Extracted {name} ({len(payload)} bytes) -> {output}")
+        return
+
+    raise SystemExit(f"File not found in archive: {target}")
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("archive", type=Path)
+    parser.add_argument("target", help="Archive path, e.g. Interface\\MainMenu.swf")
+    parser.add_argument("output", type=Path)
+    args = parser.parse_args()
+    extract_file(args.archive, args.target, args.output)
+
+
+if __name__ == "__main__":
+    main()

tools/restore-vanilla-mainmenu.ps1

@@ -0,0 +1,30 @@
+# Restore vanilla MainMenu.swf from the game BA2 archive.
+# The patched SWF must NOT be rebuilt via full FFDec script re-import — that breaks settings.
+
+param(
+    [string]$GameData = "D:\SteamLibrary\steamapps\common\Fallout 4\Data"
+)
+
+$ErrorActionPreference = "Stop"
+$repoRoot = Split-Path $PSScriptRoot -Parent
+$ba2 = Join-Path $GameData "Fallout4 - Interface.ba2"
+$extractor = Join-Path $repoRoot "tools\extract_ba2.py"
+$vanillaOut = Join-Path $repoRoot "Interface\MainMenu.swf.vanilla.bak"
+$repoSwf = Join-Path $repoRoot "Interface\MainMenu.swf"
+$deploySwf = Join-Path $GameData "Interface\MainMenu.swf"
+
+if (-not (Test-Path $ba2)) {
+    Write-Error "Interface BA2 not found: $ba2"
+}
+
+python $extractor $ba2 "Interface\MainMenu.swf" $vanillaOut
+Copy-Item -Force $vanillaOut $repoSwf
+New-Item -ItemType Directory -Force -Path (Split-Path $deploySwf -Parent) | Out-Null
+Copy-Item -Force $vanillaOut $deploySwf
+
+Write-Host "Restored vanilla MainMenu.swf to:"
+Write-Host "  $repoSwf"
+Write-Host "  $deploySwf"
+Write-Host ""
+Write-Host "Settings -> Gameplay/Display/Audio should work again."
+Write-Host "Re-add the Multiplayer button with surgical FFDec edits only (see Interface/exported/PATCH_MainMenu_Multiplayer.md)."