✅ tighten cross-target capability contracts

src-async/BitLoggerAsync_test.mbt

@@ -174,6 +174,14 @@ test "async runtime capability helpers stay consistent" {
   )
 }
 
+test "async runtime mode and worker flag encode target contract" {
+  let mode_label = async_runtime_mode_label(async_runtime_mode())
+  let worker = async_runtime_supports_background_worker()
+  inspect(mode_label == "native_worker" || mode_label == "compatibility", content="true")
+  inspect((mode_label == "native_worker") == worker, content="true")
+  inspect((mode_label == "compatibility") == !worker, content="true")
+}
+
 test "async logger state snapshot reflects current counters and runtime" {
   let logger = async_logger(
     @bitlogger.callback_sink(fn(_) {

src-async/moon.pkg

@@ -10,6 +10,9 @@ import {
 
 options(
   targets: {
+    "async_logger_shared.mbt": [ "native", "llvm", "js", "wasm", "wasm-gc" ],
+    "application_async_logger.mbt": [ "native", "llvm", "js", "wasm", "wasm-gc" ],
+    "library_async_logger.mbt": [ "native", "llvm", "js", "wasm", "wasm-gc" ],
     "async_logger_native.mbt": [ "native", "llvm" ],
     "async_logger_stub.mbt": [ "js", "wasm", "wasm-gc" ],
   },

src/BitLogger_test.mbt

@@ -560,6 +560,23 @@ test "configured non-file logger has no file runtime state" {
   inspect(logger.file_runtime_state() is None, content="true")
 }
 
+test "configured file logger mirrors backend file capability" {
+  let logger = build_logger(
+    LoggerConfig::new(
+      sink=SinkConfig::new(kind=SinkKind::File, path="config-capability.log"),
+    ),
+  )
+  inspect(logger.file_available() == native_files_supported(), content="true")
+  if logger.file_available() {
+    inspect(logger.file_state().available, content="true")
+    ignore(logger.close())
+  } else {
+    inspect(logger.file_state().available, content="false")
+    inspect(logger.file_flush(), content="false")
+    inspect(logger.file_close(), content="false")
+  }
+}
+
 test "configured logger file setters update file sink policy state" {
   let logger = build_logger(
     LoggerConfig::new(

src/BitLogger_wbtest.mbt

@@ -406,6 +406,31 @@ test "file sink availability reflects backend support" {
   }
 }
 
+test "file sink unavailable backend keeps stable fallback state" {
+  let sink = file_sink("bitlogger-unavailable.log", rotation=Some(file_rotation(64, max_backups=2)))
+  if sink.is_available() {
+    inspect(sink.state().available, content="true")
+    ignore(sink.close())
+  } else {
+    let state = sink.state()
+    inspect(native_files_supported(), content="false")
+    inspect(state.available, content="false")
+    inspect(sink.flush(), content="false")
+    inspect(sink.close(), content="false")
+    inspect(sink.write_failures(), content="0")
+    sink.write(record(Level::Info, "dropped"))
+    inspect(sink.write_failures(), content="1")
+    inspect(sink.rotation_failures(), content="0")
+    match state.rotation {
+      Some(rotation) => {
+        inspect(rotation.max_bytes, content="64")
+        inspect(rotation.max_backups, content="2")
+      }
+      None => inspect(false, content="true")
+    }
+  }
+}
+
 test "file sink rotation config normalizes invalid inputs" {
   let rotation = file_rotation(0, max_backups=0)
   inspect(rotation.max_bytes, content="1")

src/moon.pkg

@@ -12,6 +12,8 @@ import {
 
 options(
   targets: {
+    "sinks_file.mbt": [ "native", "llvm", "js", "wasm", "wasm-gc" ],
+    "runtime_file_controls.mbt": [ "native", "llvm", "js", "wasm", "wasm-gc" ],
     "file_backend_native.mbt": [ "native", "llvm" ],
     "file_backend_stub.mbt": [ "js", "wasm", "wasm-gc" ],
   },