Update Unreal SDK to websocket 2.0 (#4497)

# Description of Changes

- Updated the Unreal SDK and generated Unreal bindings for the websocket
2.0 protocol/model
  - Reworked DbConnectionBase to handle the updated message shapes
- Switched subscription handling over to new message types and
QuerySetId
- Updated reducer to ReducerResult, removal of callbacks, and set
reducer flags
  - Added event table support
- Baked in multi-module support replacing [the old
PR](<#3417>)
- Added functionality to generate module support for multiple folders in
the Unreal project (add <module>.Build.cs, <module>.h, <module>.cpp)
using the --module-name
- Add new configuration option for spacetime generate to handle module
prefix
 - Regenerated Unreal Blackholio/TestClient/QuickstartChat bindings
   - Rebuilt Unreal Blackholio's consume entity to use event tables 
 - Updated migration documentation
 - Updated the version bump tool to impact C++

# API and ABI breaking changes

- Unreal websocket/message handling updated to the new protocol
- Unreal generation now expects a real .uproject target and will stop
immediately if project
    metadata is invalid instead of continuing past setup issues.

# Expected complexity level and risk

3 - A large set of changes to update the websocket/message handling
along with heavy codegen changes to handle multi-module support

# Testing

Test coverage of the Unreal SDK will need expansion in a future ticket
once our issues with flakiness on CI is resolved.

- [x] Updated Unreal Blackholio 
- [x] Ran full Unreal SDK test suite
- [x] Built new test project using the new `--module-prefix` 
- [x] Run through Unreal Blackholio (C++ and Blueprint)
- [x] Rebuilt Unreal Blackholio with multi-module, and duplicate
generated module testing side-by-side modules that would overlap

# Review Question(s)
- [x] Updates to `spacetime init` have made the tutorial a little
confusing with pathing for the Unreal Blackholio tutorial. To fix though
we'd have to update all the commands to be more explicit, or update the
tutorial `spacetime init` to use `--project-path .` to keep pathing
simpler, thoughts?

---------

Signed-off-by: Jason Larabie <jason@clockworklabs.io>
Co-authored-by: Ryan <r.ekhoff@clockworklabs.io>

Author: JasonAtClockwork

Cargo.lock

@@ -77,7 +77,7 @@ SPACETIMEDB_REDUCER(create_user, ReducerContext ctx, std::string name) {
     }
 
     // Success path
-    ctx.db[user].insert(User{ctx.sender, name, false});
+    ctx.db[user].insert(User{ctx.sender(), name, false});
     return Ok();  // No value needed - just success
 }
 ```
@@ -638,4 +638,4 @@ SpacetimeDB loading → Server-side validation and error reporting
 - [Type System Details](README.md#features)
 - [Constraint Validation Tests](tests/type-isolation-test/)
 - [API Reference](REFERENCE.md)
-- [Quick Start Guide](QUICKSTART.md)
+- [Quick Start Guide](QUICKSTART.md)

crates/bindings-cpp/ARCHITECTURE.md

@@ -109,7 +109,7 @@ SPACETIMEDB_REDUCER(set_name, ReducerContext ctx, std::string name) {
     }
 
     // Find and update the user by identity (primary key)
-    auto user_row = ctx.db[user_identity].find(ctx.sender);
+    auto user_row = ctx.db[user_identity].find(ctx.sender());
     if (user_row.has_value()) {
         auto user = user_row.value();
         user.name = validated.value();
@@ -127,7 +127,7 @@ SPACETIMEDB_REDUCER(send_message, ReducerContext ctx, std::string text) {
         return Err(validated.error());
     }
 
-    Message msg{ctx.sender, ctx.timestamp, validated.value()};
+    Message msg{ctx.sender(), ctx.timestamp, validated.value()};
     ctx.db[message].insert(msg);
     return Ok();
 }
@@ -140,21 +140,21 @@ Lifecycle reducers are special functions called automatically by SpacetimeDB:
 ```cpp
 // Called when a client connects
 SPACETIMEDB_CLIENT_CONNECTED(client_connected, ReducerContext ctx) {
-    auto user_row = ctx.db[user_identity].find(ctx.sender);
+    auto user_row = ctx.db[user_identity].find(ctx.sender());
     if (user_row.has_value()) {
         auto user = user_row.value();
         user.online = true;
         ctx.db[user_identity].update(user);
     } else {
-        User new_user{ctx.sender, std::nullopt, true};
+        User new_user{ctx.sender(), std::nullopt, true};
         ctx.db[user].insert(new_user);
     }
     return Ok();
 }
 
 // Called when a client disconnects  
 SPACETIMEDB_CLIENT_DISCONNECTED(client_disconnected, ReducerContext ctx) {
-    auto user_row = ctx.db[user_identity].find(ctx.sender);
+    auto user_row = ctx.db[user_identity].find(ctx.sender());
     if (user_row.has_value()) {
         auto user = user_row.value();
         user.online = false;
@@ -291,4 +291,4 @@ For more complex examples, see:
 
 ---
 
-Ready to learn more? Check out the [C++ Reference Documentation](REFERENCE.md) for detailed API information.
+Ready to learn more? Check out the [C++ Reference Documentation](REFERENCE.md) for detailed API information.

crates/bindings-cpp/QUICKSTART.md

@@ -102,15 +102,15 @@ SPACETIMEDB_NAMESPACE(UserRole, "Auth")  // Will be "Auth.UserRole" in client co
 
 // User-defined reducer
 SPACETIMEDB_REDUCER(add_user, ReducerContext ctx, std::string name, std::string email) {
-    User user{ctx.sender, name, email}; // id will be auto-generated
+    User user{ctx.sender(), name, email}; // id will be auto-generated
     ctx.db[users].insert(user);
     LOG_INFO("Added user: " + name);
     return Ok();
 }
 
 // Delete user by id (using primary key)
 SPACETIMEDB_REDUCER(delete_user, ReducerContext ctx) {
-    ctx.db[users_identity].delete_by_key(ctx.sender);
+    ctx.db[users_identity].delete_by_key(ctx.sender());
     return Ok();
 }
 
@@ -121,19 +121,19 @@ SPACETIMEDB_INIT(init, ReducerContext ctx) {
 }
 
 SPACETIMEDB_CLIENT_CONNECTED(on_connect, ReducerContext ctx) {
-    LOG_INFO("Client connected: " + ctx.sender.to_hex_string());
+    LOG_INFO("Client connected: " + ctx.sender().to_hex_string());
     return Ok();
 }
 
 SPACETIMEDB_CLIENT_DISCONNECTED(on_disconnect, ReducerContext ctx) {
-    LOG_INFO("Client disconnected: " + ctx.sender.to_hex_string());
+    LOG_INFO("Client disconnected: " + ctx.sender().to_hex_string());
     return Ok();
 }
 
 // Define a view for querying data (finds the calling user)
 SPACETIMEDB_VIEW(std::optional<User>, find_my_user, Public, ViewContext ctx) {
     // Use indexed field to find user by their identity
-    return ctx.db[users_identity].find(ctx.sender);
+    return ctx.db[users_identity].find(ctx.sender());
 }
 
 // Define a procedure (pure function with return value)

crates/bindings-cpp/README.md

@@ -191,7 +191,7 @@ SPACETIMEDB_INIT(init, ReducerContext ctx) {
 // Called when a client connects
 SPACETIMEDB_CLIENT_CONNECTED(on_connect, ReducerContext ctx) {
     LOG_INFO("Client connected");
-    // ctx.sender contains the client's Identity
+    // ctx.sender() contains the client's Identity
     return Ok();
 }
 
@@ -213,7 +213,7 @@ SPACETIMEDB_REDUCER(example, ReducerContext ctx, /* params */) {
     ctx.db[table_name].insert(record);
 
     // Client identity
-    Identity client = ctx.sender;
+    Identity client = ctx.sender();
 
     // Current timestamp
     Timestamp now = ctx.timestamp;
@@ -893,7 +893,7 @@ SPACETIMEDB_TABLE(User, user, Public);
 FIELD_PrimaryKey(user, id);
 
 SPACETIMEDB_REDUCER(create_user, ReducerContext ctx, std::string name) {
-    User user{ctx.sender, name};  // ctx.sender is the calling client's identity
+    User user{ctx.sender(), name};  // ctx.sender() is the calling client's identity
     ctx.db[user_id].insert(user);
     return Ok();
 }
@@ -1138,20 +1138,20 @@ FIELD_Index(user, active);
 // Register new user
 SPACETIMEDB_REDUCER(register_user, ReducerContext ctx, std::string username, std::string email) {
     // Check if user already exists
-    auto user_opt = ctx.db[user_identity].find(ctx.sender);
+    auto user_opt = ctx.db[user_identity].find(ctx.sender());
     if (user_opt && user_opt->active) {
         return Err("User already registered");
     }
 
-    User new_user{0, ctx.sender, username, email, ctx.timestamp, true};
+    User new_user{0, ctx.sender(), username, email, ctx.timestamp, true};
     ctx.db[user].insert(new_user);
     LOG_INFO("User registered: " + username);
     return Ok();
 }
 
 // Update user profile
 SPACETIMEDB_REDUCER(update_profile, ReducerContext ctx, std::string new_username) {
-    auto user_opt = ctx.db[user_identity].find(ctx.sender);
+    auto user_opt = ctx.db[user_identity].find(ctx.sender());
     if (user_opt && user_opt->active) {
         User updated_user = *user_opt;
         updated_user.username = new_username;
@@ -1164,7 +1164,7 @@ SPACETIMEDB_REDUCER(update_profile, ReducerContext ctx, std::string new_username
 
 // Deactivate user
 SPACETIMEDB_REDUCER(deactivate_user, ReducerContext ctx) {
-    auto user_opt = ctx.db[user_identity].find(ctx.sender);
+    auto user_opt = ctx.db[user_identity].find(ctx.sender());
     if (user_opt && user_opt->active) {
         User updated_user = *user_opt;
         updated_user.active = false;
@@ -1227,7 +1227,7 @@ FIELD_Index(messages, sender);
 
 // Create channel
 SPACETIMEDB_REDUCER(create_channel, ReducerContext ctx, std::string name, std::string description, bool is_public) {
-    Channel channel{0, name, description, ctx.sender, is_public};
+    Channel channel{0, name, description, ctx.sender(), is_public};
     ctx.db[channels].insert(channel);
     LOG_INFO("Channel created: " + name);
     return Ok();
@@ -1249,7 +1249,7 @@ SPACETIMEDB_REDUCER(send_message, ReducerContext ctx, uint32_t channel_id, std::
         return Err("Channel not found");
     }
     
-    Message message{0, channel_id, ctx.sender, content, ctx.timestamp};
+    Message message{0, channel_id, ctx.sender(), content, ctx.timestamp};
     ctx.db[messages].insert(message);
     return Ok();
 }
@@ -1281,4 +1281,4 @@ SPACETIMEDB_REDUCER(update_age, ReducerContext ctx, uint32_t new_age) {
 
 ---
 
-This completes the C++ reference documentation. For more examples and advanced patterns, see the working modules in [`modules/sdk-test-cpp`](../../modules/sdk-test-cpp) and [`modules/module-test-cpp`](../../modules/module-test-cpp).
+This completes the C++ reference documentation. For more examples and advanced patterns, see the working modules in [`modules/sdk-test-cpp`](../../modules/sdk-test-cpp) and [`modules/module-test-cpp`](../../modules/module-test-cpp).

crates/bindings-cpp/REFERENCE.md

@@ -53,16 +53,18 @@ namespace SpacetimeDB {
  * @endcode
  */
 struct ProcedureContext {
+private:
     // Caller's identity - who invoked this procedure
-    Identity sender;
-    
+    Identity sender_;
+
+public:
     // Timestamp when the procedure was invoked
     Timestamp timestamp;
-    
+
     // Connection ID for the caller
     // Used to track which client connection initiated this procedure
     ConnectionId connection_id;
-    
+
 #ifdef SPACETIMEDB_UNSTABLE_FEATURES
     // HTTP client for making external requests
     // IMPORTANT: HTTP calls are NOT allowed inside transactions!
@@ -81,7 +83,11 @@ struct ProcedureContext {
     ProcedureContext() = default;
 
     ProcedureContext(Identity s, Timestamp t, ConnectionId conn_id)
-        : sender(s), timestamp(t), connection_id(conn_id) {}
+        : sender_(s), timestamp(t), connection_id(conn_id) {}
+
+    Identity sender() const {
+        return sender_;
+    }
 
     /**
      * @brief Read the current module's Identity
@@ -197,7 +203,7 @@ struct ProcedureContext {
         // Create a ReducerContext for this transaction
         // Note: connection_id converted to std::optional
         ReducerContext reducer_ctx(
-            sender,
+            sender(),
             std::optional<ConnectionId>(connection_id),
             Timestamp::from_micros_since_epoch(tx_timestamp)
         );
@@ -260,7 +266,7 @@ struct ProcedureContext {
 
         // Create a ReducerContext for this transaction
         ReducerContext reducer_ctx(
-            sender,
+            sender(),
             std::optional<ConnectionId>(connection_id),
             Timestamp::from_micros_since_epoch(tx_timestamp)
         );

crates/bindings-cpp/include/spacetimedb/procedure_context.h

@@ -17,8 +17,11 @@ namespace SpacetimeDB {
 
 // Enhanced ReducerContext with database access - matches Rust pattern
 struct ReducerContext {
-    // Core fields - directly accessible like in Rust
-    Identity sender;
+private:
+    Identity sender_;
+
+public:
+    // Core fields - sender is exposed via sender() like Rust, other fields remain directly accessible
     std::optional<ConnectionId> connection_id;
     Timestamp timestamp;
 
@@ -37,6 +40,10 @@ struct ReducerContext {
     mutable uint32_t counter_uuid_ = 0;
 
 public:
+    Identity sender() const {
+        return sender_;
+    }
+
     // Returns the authorization information for the caller of this reducer
     const AuthCtx& sender_auth() const {
         return sender_auth_;
@@ -110,7 +117,7 @@ struct ReducerContext {
     ReducerContext() : sender_auth_(AuthCtx::internal()) {}
 
     ReducerContext(Identity s, std::optional<ConnectionId> cid, Timestamp ts)
-        : sender(s), connection_id(cid), timestamp(ts), 
+        : sender_(s), connection_id(cid), timestamp(ts), 
           sender_auth_(AuthCtx::from_connection_id_opt(cid, s)) {}
 };
 

crates/bindings-cpp/include/spacetimedb/reducer_context.h

@@ -125,7 +125,7 @@
  * @usage
  * ```cpp
  * SPACETIMEDB_CLIENT_CONNECTED(on_connect, ReducerContext ctx) {
- *     LOG_INFO("Client connected: " + ctx.sender.to_hex());
+ *     LOG_INFO("Client connected: " + ctx.sender().to_hex());
  *     return Ok();
  * }
  * ```
@@ -149,7 +149,7 @@
  * @usage
  * ```cpp
  * SPACETIMEDB_CLIENT_DISCONNECTED(on_disconnect, ReducerContext ctx) {
- *     LOG_INFO("Client disconnected: " + ctx.sender.to_hex());
+ *     LOG_INFO("Client disconnected: " + ctx.sender().to_hex());
  *     return Ok();
  * }
  * ```

crates/bindings-cpp/include/spacetimedb/reducer_macros.h

@@ -53,21 +53,21 @@ struct TxContext {
 public:
     // Public references to ReducerContext fields for consistent API with Rust
     // In Rust, Deref makes tx.db work the same as ctx.db
-    // In C++, we explicitly expose references to achieve the same ergonomics
+    // In C++, we explicitly expose references where possible and provide
+    // accessors for fields exposed as methods on ReducerContext.
     DatabaseContext& db;
-    const Identity& sender;
     const Timestamp& timestamp;
     const std::optional<ConnectionId>& connection_id;
 
     // Constructor - initializes all reference members
     explicit TxContext(ReducerContext& ctx) 
         : ctx_(ctx), 
           db(ctx.db),
-          sender(ctx.sender),
           timestamp(ctx.timestamp),
           connection_id(ctx.connection_id) {}
 
     // Access to ReducerContext methods
+    Identity sender() const { return ctx_.sender(); }
     const AuthCtx& sender_auth() const { return ctx_.sender_auth(); }
     Identity identity() const { return ctx_.identity(); }
     StdbRng& rng() const { return ctx_.rng(); }

crates/bindings-cpp/include/spacetimedb/tx_context.h

@@ -25,25 +25,29 @@ namespace SpacetimeDB {
  * SPACETIMEDB_VIEW(std::vector<Item>, get_my_items, Public, ViewContext ctx) {
  *     std::vector<Item> my_items;
  *     // Filter by caller's identity using indexed field
- *     for (const auto& item : ctx.db[item_owner].filter(ctx.sender)) {
+ *     for (const auto& item : ctx.db[item_owner].filter(ctx.sender())) {
  *         my_items.push_back(item);
  *     }
  *     return Ok(my_items);
  * }
  * @endcode
  */
 struct ViewContext {
+private:
     // Caller's identity - who invoked this view
-    Identity sender;
-    
+    Identity sender_;
+
+public:
     // Read-only database access - no mutations allowed
     ReadOnlyDatabaseContext db;
 
     // Constructors
     ViewContext() = default;
 
     explicit ViewContext(Identity s)
-        : sender(s) {}
+        : sender_(s) {}
+
+    Identity sender() const { return sender_; }
 };
 
 /**