feat(sdk): add transport-free CXX bindings for C++ embedders

.github/package-filters/rs-packages-direct.yml

@@ -121,6 +121,9 @@ platform-encryption:
 dash-platform-queries:
   - packages/dash-platform-queries/**
 
+dash-platform-cxx:
+  - packages/rs-platform-cxx/**
+
 dash-sdk:
   - packages/rs-sdk/**
 

.github/package-filters/rs-packages-no-workflows.yml

@@ -136,6 +136,16 @@ platform-encryption: &platform_encryption
 dash-platform-queries: &platform_queries
   - packages/dash-platform-queries/**
 
+dash-platform-cxx:
+  - packages/rs-platform-cxx/**
+  - packages/rs-drive-proof-verifier/**
+  - *platform_queries
+  - *platform_query_wire
+  - *context_provider
+  - *dpp
+  - *drive
+  - *dapi_grpc
+
 dash-sdk: &sdk
   - packages/rs-drive-proof-verifier/**
   - packages/rs-sdk/**

.github/package-filters/rs-packages.yml

@@ -162,6 +162,17 @@ dash-platform-queries: &platform_queries
   - .github/workflows/tests*
   - packages/dash-platform-queries/**
 
+dash-platform-cxx:
+  - .github/workflows/tests*
+  - packages/rs-platform-cxx/**
+  - packages/rs-drive-proof-verifier/**
+  - *platform_queries
+  - *platform_query_wire
+  - *context_provider
+  - *dpp
+  - *drive
+  - *dapi_grpc
+
 dash-sdk: &sdk
   - .github/workflows/tests*
   - packages/rs-drive-proof-verifier/**

.github/workflows/tests-rs-workspace.yml

@@ -204,13 +204,14 @@ jobs:
           cargo check -p drive-proof-verifier --locked
           cargo check -p dash-platform-queries --locked
           cargo check -p platform-query-wire --locked
+          cargo check -p dash-platform-cxx --locked
           # Native graphs: assert the networking transport stack stays out.
           # `tonic` itself is present (dapi-grpc's generated client types) but
           # without its transport feature — which is exactly what the absence
           # of hyper/rustls/tower proves. tokio is deliberately NOT asserted
           # absent: dash-context-provider depends on dash-async, which uses it
           # on native targets, and that edge predates the queries-crate split.
-          for native_package in platform-query-wire drive-proof-verifier dash-platform-queries; do
+          for native_package in platform-query-wire drive-proof-verifier dash-platform-queries dash-platform-cxx; do
             for banned in hyper rustls tower; do
               if cargo tree -p "$native_package" -e normal -i "$banned" 2>/dev/null | grep -q .; then
                 echo "::error::$banned leaked into $native_package's dependency tree"
@@ -227,6 +228,11 @@ jobs:
             done
           done
 
+      # The C++ embedding surface must link and run from the staged headers
+      # and archive alone; the Rust tests cannot see a broken header layout.
+      - name: Link the Platform CXX embedder from C++
+        run: packages/rs-platform-cxx/scripts/cxx-smoke.sh
+
       - name: Detect immutable structure changes
         if: github.event_name == 'pull_request'
         run: |
@@ -346,6 +352,7 @@ jobs:
             --package platform-serialization \
             --package dapi-grpc \
             --package platform-query-wire \
+            --package dash-platform-cxx \
             --package json-schema-compatibility-validator \
             --package dashpay-contract \
             --package dpns-contract \

Cargo.toml

@@ -8,6 +8,7 @@ members = [
     "packages/rs-dpp",
     "packages/rs-drive",
     "packages/rs-platform-query-wire",
+    "packages/rs-platform-cxx",
     "packages/rs-platform-value",
     "packages/rs-platform-serialization",
     "packages/rs-platform-serialization-derive",

packages/rs-platform-cxx/Cargo.toml

@@ -0,0 +1,45 @@
+[package]
+name = "dash-platform-cxx"
+version.workspace = true
+authors = ["Dash Core Group <dev@dash.org>"]
+edition = "2021"
+rust-version.workspace = true
+license = "MIT"
+description = "Transport-free CXX bindings for embedding Dash Platform"
+
+[lib]
+name = "dash_platform_cxx"
+crate-type = ["staticlib", "rlib"]
+
+[dependencies]
+cxx = "1.0"
+dapi-grpc = { path = "../dapi-grpc", default-features = false, features = [
+  "platform",
+  "client",
+] }
+dash-context-provider = { path = "../rs-context-provider", default-features = false }
+dash-platform-queries = { path = "../dash-platform-queries", default-features = false }
+drive-proof-verifier = { path = "../rs-drive-proof-verifier", default-features = false }
+dpp = { path = "../rs-dpp", default-features = false, features = [
+  "state-transitions",
+  "state-transition-signing",
+  "state-transition-validation",
+  "identity-serialization",
+  "identity-hashing",
+  "bls-signatures",
+  "dpns-contract",
+  "dashpay-contract",
+] }
+platform-version = { path = "../rs-platform-version" }
+prost = "0.14"
+hex = "0.4"
+futures = "0.3"
+async-trait = "0.1"
+
+[build-dependencies]
+cxx-build = "1.0"
+
+[dev-dependencies]
+ciborium = "0.2.2"
+serde_json = "1"
+serde = { version = "1", features = ["derive"] }