feat: Android host adapter (android/truapi-host) + hosts/android submodule

.gitignore

@@ -46,8 +46,12 @@ playground/public/static.files
 # Auto-generated by truapi-codegen (typecheck fixtures for rustdoc ts blocks)
 playground/test/generated/
 
+# Local Android toolchain env (machine-specific JDK/SDK/NDK paths)
+.android-env
+
 # Auto-generated FFI / WASM binding outputs
 android/truapi-host/src/main/kotlin/generated/
+android/truapi-host/src/main/jniLibs/
 ios/truapi-host/Sources/TrUAPIHost/truapi_server.swift
 ios/truapi-host/Sources/truapi_serverFFI/
 rust/crates/truapi-server/pkg/

.gitmodules

@@ -6,3 +6,7 @@
 	path = hosts/ios
 	url = https://github.com/paritytech/polkadot-app-ios-v2
 	branch = codex/truapi-rust-core
+[submodule "hosts/android"]
+	path = hosts/android
+	url = https://github.com/paritytech/polkadot-app-android-v2
+	branch = tg/truapi-rust-core

Cargo.toml

@@ -17,3 +17,11 @@ codegen-units = 1
 panic = "abort"
 strip = "symbols"
 debug = false
+
+# UniFFI binding generation scans the host cdylib's exported metadata symbols.
+# `release` strips them (`strip = "symbols"`), so uniffi-bindgen finds nothing
+# and emits no bindings. This profile inherits release but keeps symbols, and is
+# used by the `uniffi` / `uniffi-kotlin` make targets for the codegen build only.
+[profile.codegen]
+inherits = "release"
+strip = false

Makefile

@@ -3,7 +3,7 @@
 # Run `make help` for the list of targets.
 
 .DEFAULT_GOAL := help
-.PHONY: help setup build codegen test check clean playground wasm wasm-crypto-test uniffi dotli-link dev dev-bootstrap dev-link-check e2e-dotli matrix explorer
+.PHONY: help setup build codegen test check clean playground wasm wasm-crypto-test uniffi uniffi-kotlin android-jni android-publish-local check-android-parity dotli-link dev dev-bootstrap dev-link-check e2e-dotli headless install matrix explorer
 
 CARGO ?= cargo
 TRUAPI_PKG := js/packages/truapi
@@ -66,7 +66,12 @@ wasm: ## Rebuild the truapi-server WASM artifacts under js/packages/truapi-host/
 wasm-crypto-test: ## Run crypto/vector tests on wasm32 via wasm-pack/node.
 	wasm-pack test --node rust/crates/truapi-server --test wasm_crypto_vectors --no-default-features
 
-UNIFFI_CDYLIB_DIR := target/release
+dotli-link: ## Link dotli to this checkout's local @parity/truapi packages.
+	cd $(DOTLI) && TRUAPI_REPO="$(CURDIR)" bun run link:truapi
+
+# uniffi-bindgen scans the cdylib's metadata symbols, which `release` strips, so
+# codegen builds use the unstripped `codegen` profile (see [profile.codegen]).
+UNIFFI_CDYLIB_DIR := target/codegen
 UNAME_S := $(shell uname -s)
 ifeq ($(UNAME_S),Darwin)
 UNIFFI_CDYLIB := $(UNIFFI_CDYLIB_DIR)/libtruapi_server.dylib
@@ -77,7 +82,7 @@ endif
 UNIFFI_SWIFT_TMP := target/uniffi-swift-out
 
 uniffi: ## Regenerate Swift bindings from truapi-server cdylib.
-	$(CARGO) build -p truapi-server --release --features ws-bridge
+	$(CARGO) build -p truapi-server --profile codegen --features ws-bridge
 	rm -rf $(UNIFFI_SWIFT_TMP)
 	mkdir -p $(UNIFFI_SWIFT_TMP)
 	$(CARGO) run -p uniffi-bindgen-cli -- generate \
@@ -92,8 +97,30 @@ uniffi: ## Regenerate Swift bindings from truapi-server cdylib.
 	cp $(UNIFFI_SWIFT_TMP)/truapi_serverFFI.modulemap \
 		ios/truapi-host/Sources/truapi_serverFFI/include/module.modulemap
 
-dotli-link: ## Link dotli to this checkout's local @parity/truapi packages.
-	cd $(DOTLI) && TRUAPI_REPO="$(CURDIR)" bun run link:truapi
+UNIFFI_KOTLIN_OUT := android/truapi-host/src/main/kotlin/generated
+
+uniffi-kotlin: ## Regenerate Kotlin UniFFI bindings from the truapi-server cdylib.
+	$(CARGO) build -p truapi-server --profile codegen --features ws-bridge
+	rm -rf $(UNIFFI_KOTLIN_OUT)
+	mkdir -p $(UNIFFI_KOTLIN_OUT)
+	$(CARGO) run -p uniffi-bindgen-cli -- generate \
+		--library $(UNIFFI_CDYLIB) \
+		--language kotlin \
+		--out-dir $(UNIFFI_KOTLIN_OUT)
+
+# Android ABIs to cross-compile the cdylib for. arm64 + armv7 cover physical
+# devices; x86_64 covers the emulator on Intel/Apple-silicon hosts.
+ANDROID_ABIS ?= arm64-v8a armeabi-v7a x86_64
+ANDROID_JNILIBS := android/truapi-host/src/main/jniLibs
+
+android-jni: ## Cross-compile libtruapi_server.so for Android ABIs into jniLibs (needs cargo-ndk + NDK).
+	@command -v cargo-ndk >/dev/null || { echo "cargo-ndk not found: cargo install cargo-ndk"; exit 1; }
+	$(CARGO) ndk $(foreach abi,$(ANDROID_ABIS),-t $(abi)) \
+		-o $(ANDROID_JNILIBS) \
+		build --release -p truapi-server --features ws-bridge
+
+android-publish-local: uniffi-kotlin ## Generate Kotlin bindings, then publish the AAR to ~/.m2 (needs Gradle + JDK 17). The AAR does not bundle the cdylib; consumers build it per ABI (see android-jni).
+	gradle :truapi-host:publishReleasePublicationToMavenLocal
 
 test: ## Run Rust + TypeScript client tests.
 	cargo test --workspace
@@ -110,6 +137,21 @@ check: ## Full verification suite (build, fmt, clippy, test, TS tests, playgroun
 	cd $(JS_PACKAGES)/truapi-host && npm install --no-fund --no-audit && npm test
 	cd $(PLAYGROUND) && yarn build && yarn lint
 
+ANDROID_SHELL := android/truapi-host/src/main/kotlin/io/parity/truapi/TrUAPIHost.kt
+ANDROID_SHELL_VENDORED := hosts/android/bindings/truapi-host/src/main/kotlin/io/parity/truapi/TrUAPIHost.kt
+
+check-android-parity: ## Verify the canonical android/truapi-host shell matches the copy vendored in the app (hosts/android). Skips if the submodule is not initialized.
+	@if [ ! -f "$(ANDROID_SHELL_VENDORED)" ]; then \
+		echo "Skipping android parity check: hosts/android not initialized (run 'git submodule update --init hosts/android')."; \
+	elif diff -q "$(ANDROID_SHELL)" "$(ANDROID_SHELL_VENDORED)" >/dev/null; then \
+		echo "android/truapi-host shell matches the vendored app copy."; \
+	else \
+		echo "ERROR: $(ANDROID_SHELL) has drifted from $(ANDROID_SHELL_VENDORED)."; \
+		echo "The host adapter shell is duplicated in truapi and the app; keep them in sync."; \
+		diff "$(ANDROID_SHELL)" "$(ANDROID_SHELL_VENDORED)" || true; \
+		exit 1; \
+	fi
+
 clean: ## Remove local build/test artifacts without deleting dependencies.
 	cargo clean
 	rm -rf \

README.md

@@ -64,8 +64,12 @@ js/packages/
   truapi-host/            @parity/truapi-host: WASM-backed host runtime; entries `.`
                           (shared host types), `/web` (iframe + Web Worker),
                           `/worker-runtime`
+ios/truapi-host/           Swift host adapter package over the truapi-server UniFFI core
+android/truapi-host/       Kotlin host adapter package over the truapi-server UniFFI core
 playground/                Interactive Next.js playground (truapi-playground.dot)
 hosts/dotli/               dotli host, vendored as a submodule
+hosts/ios/                 polkadot-app-ios-v2, vendored as a submodule (build/test against the core)
+hosts/android/             polkadot-app-android-v2, vendored as a submodule (build/test against the core)
 docs/                      Design docs, RFCs, feature proposals
 scripts/codegen.sh         Regenerate the TS client from the Rust source
 ```

android/.gitignore

@@ -0,0 +1,5 @@
+.gradle/
+build/
+local.properties
+*.iml
+.idea/