feat(sdk-android): snapshot property delegate + feature-scoped files + screen fix (#34)

* rename web to inspect ui

* feat(sdk-android): add camelToSnakeCase conversion

* feat(sdk-android): add snapshot() property delegate with tests

* feat(folio): add feature-scoped sanderling snapshot objects

* refactor(folio): slim FolioApplication to snapshot object references

* fix(folio): rename route snapshot to screen, update spec.ts

sdk/android/src/main/kotlin/dev/sanderling/sdk/Sanderling.kt

@@ -2,6 +2,15 @@ package dev.sanderling.sdk
 
 import android.app.Application
 import android.util.Log
+import kotlin.properties.ReadOnlyProperty
+import kotlin.reflect.KProperty
+
+internal fun String.camelToSnakeCase(): String = buildString {
+    for ((i, c) in this@camelToSnakeCase.withIndex()) {
+        if (c.isUpperCase() && i > 0) append('_')
+        append(c.lowercaseChar())
+    }
+}
 
 data class Configuration(
     val socketName: String = "sanderling-agent",
@@ -36,6 +45,8 @@ object Sanderling {
         activeRuntime.register(name, function)
     }
 
+    fun <T> snapshot(function: () -> T): SnapshotDelegate<T> = SnapshotDelegate(function)
+
     /**
      * Records a caught [Throwable] so it surfaces in the next STATE message's
      * exceptions field. Useful for coroutine CoroutineExceptionHandler,
@@ -52,3 +63,10 @@ object Sanderling {
         runtime = null
     }
 }
+
+class SnapshotDelegate<T>(private val function: () -> T) {
+    operator fun provideDelegate(thisRef: Any?, prop: KProperty<*>): ReadOnlyProperty<Any?, T> {
+        Sanderling.extract(prop.name.camelToSnakeCase(), function as () -> Any?)
+        return ReadOnlyProperty { _, _ -> function() }
+    }
+}

sdk/android/src/test/kotlin/dev/sanderling/sdk/SnapshotDelegateTest.kt

@@ -0,0 +1,95 @@
+package dev.sanderling.sdk
+
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class SnapshotDelegateTest {
+
+    @After fun tearDown() = Sanderling.stopForTest()
+
+    @Test fun camelToSnakeCaseConvertsKnownNames() {
+        assertEquals("logged_in", "loggedIn".camelToSnakeCase())
+        assertEquals("total_balance", "totalBalance".camelToSnakeCase())
+        assertEquals("txn_form_type", "txnFormType".camelToSnakeCase())
+        assertEquals("active_account_id", "activeAccountId".camelToSnakeCase())
+        assertEquals("add_account_error", "addAccountError".camelToSnakeCase())
+        assertEquals("ledger_balance", "ledgerBalance".camelToSnakeCase())
+        assertEquals("ledger_rows", "ledgerRows".camelToSnakeCase())
+        assertEquals("auth_status", "authStatus".camelToSnakeCase())
+        assertEquals("login_error", "loginError".camelToSnakeCase())
+        assertEquals("txn_error", "txnError".camelToSnakeCase())
+        assertEquals("account_count", "accountCount".camelToSnakeCase())
+        assertEquals("focused_input", "focusedInput".camelToSnakeCase())
+        assertEquals("txn_form_account_id", "txnFormAccountId".camelToSnakeCase())
+    }
+
+    @Test fun camelToSnakeCaseLeavesAlreadyLowercase() {
+        assertEquals("screen", "screen".camelToSnakeCase())
+        assertEquals("accounts", "accounts".camelToSnakeCase())
+    }
+
+    @Test fun snapshotDelegateRegistersWithDerivedKey() {
+        val transport = SocketClientTest.FakeTransport()
+        val frameThread = PauserTest.FakeFrameThread()
+        val runtime = SanderlingRuntime(
+            transport = transport,
+            pauser = Pauser(frameThread, pauseTimeoutMillis = 2_000L),
+            version = "0.0.1",
+            platform = "android",
+            appPackage = "com.example.test",
+        )
+        runtime.start()
+        // Inject runtime into Sanderling via reflection so snapshot() can register
+        val runtimeField = Sanderling::class.java.getDeclaredField("runtime")
+        runtimeField.isAccessible = true
+        runtimeField.set(Sanderling, runtime)
+
+        var callCount = 0
+        val obj = object {
+            val loggedIn by Sanderling.snapshot { callCount++; true }
+        }
+
+        val snapshot = runtime.snapshot()
+        assertEquals(true, snapshot["logged_in"])
+        assertEquals(1, callCount)
+
+        // getValue delegates back to lambda
+        callCount = 0
+        val value = obj.loggedIn
+        assertEquals(true, value)
+        assertEquals(1, callCount)
+
+        runtime.stop()
+        frameThread.shutdown()
+    }
+
+    @Test fun snapshotDelegateGetValueReturnsFreshResult() {
+        val transport = SocketClientTest.FakeTransport()
+        val frameThread = PauserTest.FakeFrameThread()
+        val runtime = SanderlingRuntime(
+            transport = transport,
+            pauser = Pauser(frameThread, pauseTimeoutMillis = 2_000L),
+            version = "0.0.1",
+            platform = "android",
+            appPackage = "com.example.test",
+        )
+        runtime.start()
+        val runtimeField = Sanderling::class.java.getDeclaredField("runtime")
+        runtimeField.isAccessible = true
+        runtimeField.set(Sanderling, runtime)
+
+        var counter = 0
+        val obj = object {
+            val accountCount by Sanderling.snapshot { counter }
+        }
+
+        counter = 5
+        assertEquals(5, obj.accountCount)
+        counter = 10
+        assertEquals(10, obj.accountCount)
+
+        runtime.stop()
+        frameThread.shutdown()
+    }
+}