contract: 16-bit CharFlag; me.maxdiff and me.ladder from the character flags

src/backends/lod114d/game/GameHelpers.cpp

@@ -311,7 +311,7 @@ uint32_t GetWeaponSwitch() {
 }
 
 GameType GetGameType() {
-    return static_cast<GameType>(*d2client::gbExpCharFlag);
+    return HasFlag(GetCharFlags(), CharFlag::Expansion) ? GameType::Expansion : GameType::Classic;
 }
 
 uint32_t GetMercReviveCost() {
@@ -348,19 +348,9 @@ std::string GetRealmShort() {
     return data != nullptr ? ToString(data->szRealmName2) : std::string{};
 }
 
-Difficulty GetMaxDiff() {
-    auto* data = *d2launch::gpBnetData;
-    return data != nullptr ? static_cast<Difficulty>(data->nMaxDiff) : Difficulty::Normal;
-}
-
 CharFlag GetCharFlags() {
     auto* data = *d2launch::gpBnetData;
-    return data != nullptr ? static_cast<CharFlag>(data->nCharFlags) : CharFlag{};
-}
-
-std::optional<uint8_t> IsLadder() {
-    auto* data = *d2launch::gpBnetData;
-    return data != nullptr ? std::optional{data->nLadderFlag} : std::nullopt;
+    return data != nullptr ? data->nCharFlags : CharFlag{};
 }
 
 // === GameStructInfo Queries ===

src/backends/lod114d/hooks/Intercepts.cpp

@@ -58,13 +58,15 @@
 
 #include <array>
 #include <atomic>
+#include <bit>
 #include <chrono>
 #include <cstdint>
 #include <filesystem>
 #include <format>
 #include <span>
 #include <string>
 #include <system_error>
+#include <utility>
 
 #include "game/GameCallbacks.h"
 #include "game/GameHelpers.h"
@@ -700,10 +702,11 @@ extern "C" D2UnitStrc* OnGetSelectedUnit() {
 }
 
 // P9: CongratsScreen. Original CALL/5 at 0x44EBEF -> CongratsScreen_I.
-// Bumps `nMaxDiff` to 10 (any value high enough to enable the next
-// difficulty selector) after the Baal credits roll on any non-Hell
-// difficulty, so Nightmare unlocks after Normal-Baal and Hell unlocks
-// after Nightmare-Baal.
+// Bumps the character flags' progression (CharFlag::ProgressionMask, the acts
+// completed across all difficulties; the byte the reference calls nMaxDiff) to
+// 10 - any value high enough to enable the next difficulty selector - after
+// the Baal credits roll on any non-Hell difficulty, so Nightmare unlocks after
+// Normal-Baal and Hell unlocks after Nightmare-Baal.
 //
 // Reference d2bs (D2Handlers.cpp:436) fired this only on Nightmare:
 //     if (D2CLIENT_GetDifficulty() == 1) { ... nMaxDiff = 10; }
@@ -717,7 +720,10 @@ extern "C" void SetMaxDiff() {
     if (game::GetDifficulty() < game::Difficulty::Hell && *imports::d2client::gbExpCharFlag != 0) {
         auto* pData = *imports::d2launch::gpBnetData;
         if (pData != nullptr) {
-            pData->nMaxDiff = 10;
+            constexpr uint16_t UNLOCKED_PROGRESSION = 10;
+            constexpr auto PROGRESSION_SHIFT = std::countr_zero(std::to_underlying(game::CharFlag::ProgressionMask));
+            pData->nCharFlags = (pData->nCharFlags & ~game::CharFlag::ProgressionMask) |
+                                static_cast<game::CharFlag>(UNLOCKED_PROGRESSION << PROGRESSION_SHIFT);
         }
     }
 }

src/backends/lod114d/imports/extras/BnetData.h

@@ -1,8 +1,11 @@
 #pragma once
 
 #include <array>
+#include <cstddef>
 #include <cstdint>
 
+#include "game/Constants.h"
+
 // Battle.net account state - d2bs-internal struct. D2MOO does not model BNCS.
 // Field layout reverse-engineered against 1.14d; size verified by static_assert.
 // NOLINTBEGIN(readability-identifier-naming) - struct fields match binary layout
@@ -27,8 +30,7 @@ struct BnetData {
     std::array<char, 0x08> szRealmName;    // 0xD5
     std::array<uint8_t, 0x111> _8;         // 0xDD
     uint8_t nCharClass;                    // 0x1EE
-    uint8_t nCharFlags;                    // 0x1EF
-    uint8_t nMaxDiff;                      // 0x1F0
+    game::CharFlag nCharFlags;             // 0x1EF word, SelectedCharBnetSingleTcpIp 0x434A5A
     std::array<uint8_t, 0x1F> _9;          // 0x1F1
     uint8_t nCreatedGameDifficulty;        // 0x210
     void* _10;                             // 0x211
@@ -47,6 +49,7 @@ struct BnetData {
 };
 
 static_assert(sizeof(BnetData) == 0x3C6, "BnetData must be 0x3C6 bytes");
+static_assert(offsetof(BnetData, nCharFlags) == 0x1EF);
 
 #pragma pack(pop)
 

src/contract/game/Constants.h

@@ -29,11 +29,11 @@ constexpr uint32_t MAX_WAYPOINT_ID = 40;
 // RosterUnit::wPartyId sentinel for "not in a party".
 constexpr uint16_t NO_PARTY_ID = std::numeric_limits<uint16_t>::max();
 
-// Character flags (me.charflags; 1.14d's BnetData::nCharFlags). Values follow
-// D2MOO's CLIENTSAVEFLAG_*, which D2R keeps; the names of the bits D2MOO leaves
-// unnamed are D2R's.
+// Character flags (me.charflags; 1.14d's BnetData::nCharFlags, a 16-bit word).
+// Values follow D2MOO's CLIENTSAVEFLAG_*; the bits D2MOO leaves unnamed are
+// named after later game versions.
 /// @flags
-enum class CharFlag : uint32_t {
+enum class CharFlag : uint16_t {
     Newbie = 0x0001,
     Error = 0x0002,  // D2MOO: set at character creation for realm characters
     Hardcore = 0x0004,

src/contract/game/GameHelpers.h

@@ -52,9 +52,7 @@ std::string GetAccountName();
 std::string GetPlayerName();
 std::string GetRealmName();
 std::string GetRealmShort();
-Difficulty GetMaxDiff();
 CharFlag GetCharFlags();
-std::optional<uint8_t> IsLadder();
 
 // === GameStructInfo Queries ===
 std::string GetGameName();

src/runtime/api/classes/ClassRegistry.cpp

@@ -1,6 +1,7 @@
 #include "ClassRegistry.h"
 
 #include <array>
+#include <bit>
 #include <utility>
 
 #include "api/core/Convert.h"
@@ -182,11 +183,17 @@ v8::Local<v8::Object> CreateMeObject(v8::Isolate* isolate, v8::Local<v8::Context
             info.GetReturnValue().Set(static_cast<uint32_t>(game::GetDifficulty()));
         });
 
-    /// @description Highest difficulty unlocked for this character.
-    /// @type {Difficulty}
+    /// @description The character's progression: the number of acts completed across all difficulties, the
+    /// ProgressionMask bits of charflags (bits 8-12) shifted down - not a difficulty. A difficulty takes 5 acts in
+    /// an expansion game and 4 in classic, so the highest difficulty unlocked is min(maxdiff / acts, 2)
+    /// (0 Normal, 1 Nightmare, 2 Hell): an expansion character that has finished Nightmare reads 10.
+    /// @type {number}
     JSUnit::InstanceProperty(
         isolate, context, me, "maxdiff", +[](v8::Local<v8::Name>, const v8::PropertyCallbackInfo<v8::Value>& info) {
-            info.GetReturnValue().Set(static_cast<uint32_t>(game::GetMaxDiff()));
+            constexpr auto PROGRESSION_MASK = std::to_underlying(game::CharFlag::ProgressionMask);
+            const auto progression =
+                (std::to_underlying(game::GetCharFlags()) & PROGRESSION_MASK) >> std::countr_zero(PROGRESSION_MASK);
+            info.GetReturnValue().Set(static_cast<uint32_t>(progression));
         });
 
     /// @description Name of the joined/created game. Empty string when not in a game.
@@ -245,12 +252,11 @@ v8::Local<v8::Object> CreateMeObject(v8::Isolate* isolate, v8::Local<v8::Context
             info.GetReturnValue().Set(game::Unit::CursorItem().has_value());
         });
 
-    /// @description Ladder status flag of the current realm/game; undefined when the status is unknown (out of game).
-    /// @type {number}
+    /// @description Whether the character is a ladder character: the Ladder bit of charflags.
+    /// @type {boolean}
     JSUnit::InstanceProperty(
         isolate, context, me, "ladder", +[](v8::Local<v8::Name>, const v8::PropertyCallbackInfo<v8::Value>& info) {
-            if (const auto ladder = game::IsLadder())
-                info.GetReturnValue().Set(convert::ToJS(info.GetIsolate(), static_cast<double>(ladder.value())));
+            info.GetReturnValue().Set(HasFlag(game::GetCharFlags(), game::CharFlag::Ladder));
         });
 
     /// @description Current network latency to the game server, in milliseconds.

src/runtime/components/characterstate/CharacterState.cpp

@@ -120,9 +120,7 @@ json BuildIdentity() {
     identity["charFlags"] = std::to_underlying(game::GetCharFlags());
     // The game's own type, read past the compatibility flags like the rest of the capture.
     identity["gameType"] = std::to_underlying(game::GetGameType());
-    // hardcore/expansion are derivable from charFlags; ladder is a separate BnetData
-    // flag, so it stays here.
-    identity["ladder"] = game::IsLadder().value_or(0) != 0;
+    identity["ladder"] = HasFlag(game::GetCharFlags(), game::CharFlag::Ladder);
     return identity;
 }
 

tests/runtime/fakes/GameHelpers.cpp

@@ -74,15 +74,9 @@ std::string GetRealmName() {
 std::string GetRealmShort() {
     return "";
 }
-Difficulty GetMaxDiff() {
-    return Difficulty::Normal;
-}
 CharFlag GetCharFlags() {
     return CharFlag{};
 }
-std::optional<uint8_t> IsLadder() {
-    return {};
-}
 
 // === GameStructInfo Queries ===
 std::string GetGameName() {