Wire local TDLib into iOS FFI build

docs/ios/tdlib-linking.md

@@ -7,7 +7,7 @@ Local toolchain status:
 - `scripts/check-ios-prereqs.sh` passes.
 - `scripts/run-ios-simulator-app.sh` launches the fake-backed SwiftUI shell in iOS Simulator.
 
-Current real TDLib blocker:
+Previous real TDLib blocker:
 
 ```bash
 DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer cargo build -p tele-ios-ffi --target aarch64-apple-ios-sim --release
@@ -25,10 +25,83 @@ Interpretation:
 
 - Rust, Swift, Xcode, and the iOS simulator runtime are working.
 - The fake-backed iOS app shell can be built, installed, launched, and rendered.
-- Real TDLib iOS linking is blocked because `tdlib-rs` 1.2.0 does not publish the iOS static library artifact requested by its `download-tdlib` build script.
+- `download-tdlib` cannot be used for iOS because `tdlib-rs` 1.2.0 does not publish the iOS artifact requested by its build script.
 
-Next viable paths:
+Current real TDLib status:
 
-1. Build TDLib for `iphoneos` and `iphonesimulator` locally and switch the Rust dependency path to `local-tdlib` or `pkg-config`.
-2. Add a fake-only `tele-ios-ffi` build feature that avoids linking TDLib for simulator UI work, while keeping real TDLib behind a separate feature.
-3. Replace the `tdlib-rs` packaging path for iOS with a lower-level C ABI/XCFramework if UniFFI plus `tdlib-rs` cannot link cleanly on device.
+- `scripts/build-tdlib-ios.sh` builds TDLib `1.8.29` locally for iOS device and simulator.
+- `.build/tdlib-ios/iphoneos/lib/libtdjson.1.8.29.dylib` is `arm64`.
+- `.build/tdlib-ios/iphonesimulator/lib/libtdjson.1.8.29.dylib` is a universal `x86_64` + `arm64` simulator dylib.
+- `scripts/check-ios-tdlib-linking.sh` builds `tele-ios-ffi` for `aarch64-apple-ios-sim` with local TDLib.
+- `IOS_RUST_TARGET=aarch64-apple-ios scripts/build-ios-ffi-with-local-tdlib.sh` builds `tele-ios-ffi` for device with local TDLib.
+- `scripts/build-ios-real-ffi-xcframework.sh` packages simulator Rust slices into `tele_ios_ffi.xcframework`, packages local `libtdjson` into `tdjson.xcframework`, and writes generated Swift bindings into the Swift package's local `Generated` path.
+- `TELE_IOS_USE_LOCAL_FFI=1 scripts/build-ios-simulator-app.sh` builds and packages the SwiftUI simulator app against the real Rust/TDLib FFI path, including `Frameworks/libtdjson.dylib` in the `.app` bundle.
+- The repo patches `tdlib-rs` through `crates/vendor/tdlib-rs` because upstream `src/build.rs` does not handle `target_os = "ios"` for `local-tdlib`.
+
+Selected path:
+
+1. Keep `download-tdlib` for the terminal/macOS build path.
+2. Build TDLib locally for iOS and iOS Simulator from the TDLib source commit matching TDLib `1.8.29`.
+3. Build `tele-ios-ffi` with `tele-core/tdlib-local` and `LOCAL_TDLIB_PATH`.
+4. Package the resulting Rust FFI library and TDLib dylib into the iOS app/XCFramework path.
+
+The TDLib source commit used for `1.8.29` is:
+
+```text
+af69dd4397b6dc1bf23ba0fd0bf429fcba6454f6
+```
+
+This can be checked with:
+
+```bash
+npm info prebuilt-tdlib@td-1.8.29 tdlib --json
+```
+
+Build local TDLib artifacts:
+
+```bash
+DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer scripts/build-tdlib-ios.sh
+```
+
+This writes local, untracked outputs to:
+
+```text
+.build/tdlib-ios/iphoneos/
+.build/tdlib-ios/iphonesimulator/
+```
+
+Build the real iOS FFI path against local TDLib:
+
+```bash
+DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer scripts/build-ios-ffi-with-local-tdlib.sh
+```
+
+or for a device target:
+
+```bash
+DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer IOS_RUST_TARGET=aarch64-apple-ios scripts/build-ios-ffi-with-local-tdlib.sh
+```
+
+Package the real FFI path for the Swift app and build the simulator `.app`:
+
+```bash
+DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer scripts/build-ios-real-ffi-xcframework.sh
+TELE_IOS_USE_LOCAL_FFI=1 DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer scripts/build-ios-simulator-app.sh
+```
+
+Known local prerequisites:
+
+- Xcode with the iOS SDK installed.
+- Homebrew build tools: `brew install cmake gperf coreutils`.
+- Rust iOS targets: `rustup target add aarch64-apple-ios-sim aarch64-apple-ios`.
+- `scripts/build-tdlib-ios.sh` builds only the required OpenSSL platforms through TDLib's vendored `Python-Apple-support` flow, with a local patch for the simulator target triple under Xcode 26.
+- TDLib CMake uses `TDLIB_IOS_DEPLOYMENT_TARGET=17.0` by default to match the Swift package minimum iOS version.
+- TDLib's `prepare_cross_compiling` target is run as a host-side generation step before cross-compiling, so generated TL/MIME sources exist for the iOS build.
+
+Example local blocker if these tools are missing:
+
+```text
+Required tool not found: cmake
+```
+
+CMake 4.x compatibility is handled by passing `-DCMAKE_POLICY_VERSION_MINIMUM=3.5` to TDLib's configure step.