docs(targets): add supported target matrix and README link

README.md

@@ -24,6 +24,10 @@ To use this package you need:
 - Rust toolchain with `cargo` and the native targets you intend to build. You can install Rust via [rustup](https://rustup.rs/).
 - Flutter SDK if you plan to use the package in a Flutter app or run the [Flutter demo](bdk_demo/).
 
+## Supported targets
+
+See [SUPPORTED_TARGETS.md](SUPPORTED_TARGETS.md) for the current platform/architecture matrix and support status.
+
 ### Add to your project
 
 **Via git:**

SUPPORTED_TARGETS.md

@@ -0,0 +1,39 @@
+# Supported Targets
+
+This document defines the current target matrix for `bdk_dart`.
+It is the source of truth for what is currently validated versus planned.
+
+## Status labels
+
+- `CI-validated`: covered by the current CI workflow.
+- `Targeted`: Rust target is configured, but CI coverage is not complete yet.
+- `Not supported`: no current support.
+
+## Runtime scope
+
+- `Dart CLI`: supported where native assets can build and load the Rust library.
+- `Flutter`: intended for mobile and desktop targets listed below.
+- `Web`: not supported (the package depends on `dart:ffi` / native assets).
+
+## Matrix
+
+| Platform | Architecture | Rust target triple | Status | CI coverage |
+| --- | --- | --- | --- | --- |
+| Android | `arm64-v8a` | `aarch64-linux-android` | Targeted | No |
+| Android | `x86_64` | `x86_64-linux-android` | Targeted | No |
+| Android | `armeabi-v7a` | `armv7-linux-androideabi` | Targeted | No |
+| iOS | `arm64` (device) | `aarch64-apple-ios` | Targeted | No |
+| iOS | `arm64` (simulator) | `aarch64-apple-ios-sim` | Targeted | No |
+| iOS | `x86_64` (simulator) | `x86_64-apple-ios` | Targeted | No |
+| macOS | `arm64` | `aarch64-apple-darwin` | CI-validated | Yes (`macos-latest`) |
+| macOS | `x86_64` | `x86_64-apple-darwin` | Targeted | No |
+| Linux | `x86_64` | `x86_64-unknown-linux-gnu` | CI-validated | Yes (`ubuntu-latest`) |
+| Linux | `arm64` | `aarch64-unknown-linux-gnu` | Targeted | No |
+| Windows | `x86_64` | `x86_64-pc-windows-msvc` | Targeted | No |
+| Windows | `arm64` | `aarch64-pc-windows-msvc` | Targeted | No |
+| Web | n/a | n/a | Not supported | n/a |
+
+## Notes
+
+- CI coverage above refers to the current workflow at `.github/workflows/ci.yml`.
+- Expanding CI coverage is tracked in issue `#25`.