feat: Phase 28.1.2 — dual-network binding + OkHttp clients

- NetworkBinder: discovers Pi hotspot WiFi (no-internet) and cellular networks
  via ConnectivityManager, creates per-network socket-bound OkHttpClients
- DualNetworkTestScreen: real OkHttp calls to 10.42.0.1/api/gps/status and
  yaris.ceaf.dev/health, simultaneous "Test Both" gate button
- MainActivity: discovers networks at startup, passes bound clients to screen
- Retrofit interfaces (PiApi, ServerApi) + DTOs (GpsStatus, HealthResponse)
- Uncommented OkHttp/Retrofit/kotlinx-serialization deps in build.gradle.kts

android/app/build.gradle.kts

@@ -77,12 +77,12 @@ dependencies {
     implementation(libs.lifecycle.runtime.compose)
     implementation(libs.lifecycle.viewmodel.compose)
 
-    // Network — will be used in 28.1.2
+    // Network
-    // implementation(libs.okhttp)
+    implementation(libs.okhttp)
-    // implementation(libs.okhttp.logging)
+    implementation(libs.okhttp.logging)
-    // implementation(libs.retrofit)
+    implementation(libs.retrofit)
-    // implementation(libs.retrofit.kotlinx.serialization)
+    implementation(libs.retrofit.kotlinx.serialization)
-    // implementation(libs.kotlinx.serialization.json)
+    implementation(libs.kotlinx.serialization.json)
 
     // Coroutines
     implementation(libs.kotlinx.coroutines.android)

android/app/src/main/java/com/yarisobd/app/DualNetworkTestScreen.kt

@@ -2,11 +2,14 @@ package com.yarisobd.app
 
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
 import androidx.compose.material3.Button
 import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.Card
@@ -14,29 +17,54 @@ import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontFamily
 import androidx.compose.ui.unit.dp
+import kotlinx.coroutines.async
+import kotlinx.coroutines.launch
+import okhttp3.OkHttpClient
+import okhttp3.Request
 
 /**
  * Phase 28.1 gate screen — proves dual-network binding works on the real device
  * before building anything else.
  *
- * Two buttons:
+ * Two networks, two OkHttpClients (each socket-bound to its respective network):
- *  "Test Pi" → calls 10.42.0.1/api/gps/status over WiFi
+ *  - Pi client → WiFi → 10.42.0.1/api/gps/status
- *  "Test Server" → calls yaris.ceaf.dev/health over cellular
+ *  - Server client → Cellular → yaris.ceaf.dev/health
  *
  * Both must succeed simultaneously while the phone is associated with the
  * Pi's no-internet hotspot ("yaris 911").
  */
 @Composable
-fun DualNetworkTestScreen() {
+fun DualNetworkTestScreen(
+    piClient: OkHttpClient?,
+    serverClient: OkHttpClient?,
+) {
+    val scope = rememberCoroutineScope()
+    val scroll = rememberScrollState()
+
+    var piResult by remember { mutableStateOf<String?>(null) }
+    var serverResult by remember { mutableStateOf<String?>(null) }
+    var bothResult by remember { mutableStateOf<String?>(null) }
+    var isLoading by remember { mutableStateOf(false) }
+
+    val piAvailable = piClient != null
+    val serverAvailable = serverClient != null
+
     Column(
         modifier = Modifier
             .fillMaxSize()
+            .verticalScroll(scroll)
             .padding(24.dp),
         horizontalAlignment = Alignment.CenterHorizontally,
-        verticalArrangement = Arrangement.Center
+        verticalArrangement = Arrangement.Top
     ) {
         Text(
             text = "yaris-obd",
@@ -44,7 +72,7 @@ fun DualNetworkTestScreen() {
             color = MaterialTheme.colorScheme.primary
         )
 
-        Spacer(modifier = Modifier.height(8.dp))
+        Spacer(modifier = Modifier.height(4.dp))
 
         Text(
             text = "Phase 28.1 — Network Binding Proof",
@@ -52,7 +80,37 @@ fun DualNetworkTestScreen() {
             color = MaterialTheme.colorScheme.onSurfaceVariant
         )
 
-        Spacer(modifier = Modifier.height(32.dp))
+        Spacer(modifier = Modifier.height(8.dp))
+
+        // Network status
+        Card(
+            modifier = Modifier.fillMaxWidth(),
+            colors = CardDefaults.cardColors(
+                containerColor = MaterialTheme.colorScheme.surfaceContainerHigh
+            )
+        ) {
+            Column(modifier = Modifier.padding(12.dp)) {
+                Text(
+                    text = "Network Status",
+                    style = MaterialTheme.typography.titleSmall
+                )
+                Spacer(modifier = Modifier.height(4.dp))
+                Text(
+                    text = "Pi WiFi: ${if (piAvailable) "✓ Bound" else "✗ Not found"}",
+                    style = MaterialTheme.typography.bodySmall,
+                    color = if (piAvailable) MaterialTheme.colorScheme.primary
+                    else MaterialTheme.colorScheme.error
+                )
+                Text(
+                    text = "Cellular:  ${if (serverAvailable) "✓ Bound" else "✗ Not found (using default)"}",
+                    style = MaterialTheme.typography.bodySmall,
+                    color = if (serverAvailable) MaterialTheme.colorScheme.primary
+                    else MaterialTheme.colorScheme.error
+                )
+            }
+        }
+
+        Spacer(modifier = Modifier.height(16.dp))
 
         // Pi WiFi test
         Card(
@@ -61,29 +119,41 @@ fun DualNetworkTestScreen() {
                 containerColor = MaterialTheme.colorScheme.surfaceContainerHigh
             )
         ) {
-            Column(
+            Column(modifier = Modifier.padding(16.dp)) {
-                modifier = Modifier.padding(16.dp)
-            ) {
                 Text(
                     text = "Pi Hotspot (WiFi)",
                     style = MaterialTheme.typography.titleMedium
                 )
                 Text(
-                    text = "Target: 10.42.0.1/api/gps/status",
+                    text = "GET 10.42.0.1/api/gps/status",
                     style = MaterialTheme.typography.bodySmall,
                     color = MaterialTheme.colorScheme.onSurfaceVariant
                 )
-                Spacer(modifier = Modifier.height(12.dp))
+                Spacer(modifier = Modifier.height(8.dp))
+                Row {
                     Button(
-                    onClick = { /* TODO: 28.1.2 — WiFi-bound OkHttp call */ },
+                        onClick = {
-                    modifier = Modifier.fillMaxWidth()
+                            isLoading = true
+                            piResult = null
+                            scope.launch {
+                                piResult = callPi(piClient)
+                                isLoading = false
+                            }
+                        },
+                        enabled = piAvailable && !isLoading,
+                        modifier = Modifier.weight(1f)
                     ) {
                         Text("Test Pi")
                     }
                 }
+                piResult?.let { result ->
+                    Spacer(modifier = Modifier.height(8.dp))
+                    ResultBlock(result)
+                }
+            }
         }
 
-        Spacer(modifier = Modifier.height(16.dp))
+        Spacer(modifier = Modifier.height(12.dp))
 
         // Server cellular test
         Card(
@@ -92,22 +162,29 @@ fun DualNetworkTestScreen() {
                 containerColor = MaterialTheme.colorScheme.surfaceContainerHigh
             )
         ) {
-            Column(
+            Column(modifier = Modifier.padding(16.dp)) {
-                modifier = Modifier.padding(16.dp)
-            ) {
                 Text(
                     text = "Remote Server (Cellular)",
                     style = MaterialTheme.typography.titleMedium
                 )
                 Text(
-                    text = "Target: yaris.ceaf.dev/health",
+                    text = "GET yaris.ceaf.dev/health",
                     style = MaterialTheme.typography.bodySmall,
                     color = MaterialTheme.colorScheme.onSurfaceVariant
                 )
-                Spacer(modifier = Modifier.height(12.dp))
+                Spacer(modifier = Modifier.height(8.dp))
+                Row {
                     Button(
-                    onClick = { /* TODO: 28.1.2 — Cellular-bound OkHttp call */ },
+                        onClick = {
-                    modifier = Modifier.fillMaxWidth(),
+                            isLoading = true
+                            serverResult = null
+                            scope.launch {
+                                serverResult = callServer(serverClient)
+                                isLoading = false
+                            }
+                        },
+                        enabled = serverAvailable && !isLoading,
+                        modifier = Modifier.weight(1f),
                         colors = ButtonDefaults.buttonColors(
                             containerColor = MaterialTheme.colorScheme.secondary
                         )
@@ -115,14 +192,132 @@ fun DualNetworkTestScreen() {
                         Text("Test Server")
                     }
                 }
+                serverResult?.let { result ->
+                    Spacer(modifier = Modifier.height(8.dp))
+                    ResultBlock(result)
+                }
+            }
         }
 
-        Spacer(modifier = Modifier.height(24.dp))
+        Spacer(modifier = Modifier.height(12.dp))
+
+        // Simultaneous test
+        Button(
+            onClick = {
+                isLoading = true
+                piResult = null
+                serverResult = null
+                bothResult = null
+                scope.launch {
+                    val piDeferred = async { callPi(piClient) }
+                    val serverDeferred = async { callServer(serverClient) }
+                    val pi = piDeferred.await()
+                    val server = serverDeferred.await()
+                    piResult = pi
+                    serverResult = server
+
+                    val piOk = pi?.startsWith("✓") == true
+                    val serverOk = server?.startsWith("✓") == true
+                    bothResult = when {
+                        piOk && serverOk -> "✓ BOTH NETWORKS WORK SIMULTANEOUSLY — gate passed!"
+                        piOk -> "⚠ Pi OK but server failed — check cellular data is on"
+                        serverOk -> "⚠ Server OK but Pi failed — are you on the yaris 911 hotspot?"
+                        else -> "✗ Both failed"
+                    }
+                    isLoading = false
+                }
+            },
+            enabled = piAvailable && serverAvailable && !isLoading,
+            modifier = Modifier.fillMaxWidth()
+        ) {
+            Text(if (isLoading) "Testing..." else "Test Both Simultaneously")
+        }
+
+        bothResult?.let { result ->
+            Spacer(modifier = Modifier.height(12.dp))
+            val isSuccess = result.startsWith("✓")
+            Card(
+                modifier = Modifier.fillMaxWidth(),
+                colors = CardDefaults.cardColors(
+                    containerColor = if (isSuccess)
+                        MaterialTheme.colorScheme.primaryContainer
+                    else MaterialTheme.colorScheme.errorContainer
+                )
+            ) {
+                Text(
+                    text = result,
+                    modifier = Modifier.padding(16.dp),
+                    style = MaterialTheme.typography.bodyLarge
+                )
+            }
+        }
+
+        Spacer(modifier = Modifier.height(16.dp))
 
         Text(
-            text = "Connect phone to \"yaris 911\" hotspot first.",
+            text = "Connect phone to \"yaris 911\" hotspot, ensure cellular data is ON, then test.",
             style = MaterialTheme.typography.bodySmall,
             color = MaterialTheme.colorScheme.onSurfaceVariant
         )
     }
 }
+
+@Composable
+private fun ResultBlock(text: String) {
+    val isSuccess = text.startsWith("✓")
+    Card(
+        colors = CardDefaults.cardColors(
+            containerColor = if (isSuccess)
+                MaterialTheme.colorScheme.surfaceContainerLow
+            else MaterialTheme.colorScheme.errorContainer
+        )
+    ) {
+        Text(
+            text = text,
+            modifier = Modifier.padding(8.dp),
+            style = MaterialTheme.typography.bodySmall.copy(fontFamily = FontFamily.Monospace),
+            color = if (isSuccess) MaterialTheme.colorScheme.primary
+            else MaterialTheme.colorScheme.onErrorContainer
+        )
+    }
+}
+
+// --- Network call helpers ---
+
+private suspend fun callPi(client: OkHttpClient?): String {
+    if (client == null) return "✗ Pi WiFi network not available — connect to yaris 911 hotspot"
+
+    return try {
+        val request = Request.Builder()
+            .url("http://10.42.0.1/api/gps/status")
+            .get()
+            .build()
+        val response = client.newCall(request).execute()
+        if (response.isSuccessful) {
+            "✓ Pi OK (${response.code}) — ${response.body?.string()?.take(200) ?: "no body"}"
+        } else {
+            "✗ Pi HTTP ${response.code} — ${response.message}"
+        }
+    } catch (e: Exception) {
+        "✗ Pi error: ${e.javaClass.simpleName}: ${e.message}"
+    }
+}
+
+private suspend fun callServer(client: OkHttpClient?): String {
+    val c = client ?: OkHttpClient()
+
+    return try {
+        val request = Request.Builder()
+            .url("https://yaris.ceaf.dev/health")
+            .get()
+            .build()
+        val response = c.newCall(request).execute()
+        if (response.isSuccessful) {
+            "✓ Server OK (${response.code}) — ${response.body?.string() ?: "no body"}"
+        } else {
+            "✗ Server HTTP ${response.code} — ${response.message}"
+        }
+    } catch (e: Exception) {
+        "✗ Server error: ${e.javaClass.simpleName}: ${e.message}"
+    }
+}

android/app/src/main/java/com/yarisobd/app/MainActivity.kt

@@ -4,28 +4,65 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import com.yarisobd.app.ui.theme.YarisOBDTheme
+import com.yarisobd.app.util.NetworkBinder
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.runBlocking
+import okhttp3.OkHttpClient
 
 class MainActivity : ComponentActivity() {
 
+    // Discovered at startup — null if the network isn't available
+    private var piClient: OkHttpClient? = null
+    private var serverClient: OkHttpClient? = null
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
 
+        // Discover networks synchronously at startup (fast — just reads
+        // ConnectivityManager state, no network I/O)
+        discoverNetworks()
+
         setContent {
             YarisOBDTheme {
                 Surface(
                     modifier = Modifier.fillMaxSize(),
                     color = MaterialTheme.colorScheme.background
                 ) {
-                    // Placeholder — replaced by nav host in 28.1.2
+                    DualNetworkTestScreen(
-                    DualNetworkTestScreen()
+                        piClient = piClient,
+                        serverClient = serverClient,
+                    )
                 }
             }
         }
     }
+
+    private fun discoverNetworks() {
+        val context = applicationContext
+
+        // Blocking is fine here — NetworkBinder discovery just reads
+        // ConnectivityManager state, no network calls.
+        runBlocking(Dispatchers.Main) {
+            val piNetwork = NetworkBinder.findPiHotspotNetwork(context)
+            piClient = piNetwork?.let { NetworkBinder.createBoundClient(it) }
+
+            val cellNetwork = NetworkBinder.findCellularNetwork(context)
+                ?: NetworkBinder.findDefaultNetwork(context)
+            serverClient = cellNetwork?.let { NetworkBinder.createBoundClient(it) }
+        }
+    }
 }

android/app/src/main/java/com/yarisobd/app/data/remote/PiApi.kt

@@ -0,0 +1,27 @@
+package com.yarisobd.app.data.remote
+
+import com.yarisobd.app.data.remote.dto.GpsStatus
+import retrofit2.http.GET
+
+/**
+ * REST API for the Pi's local web server (10.42.0.1 over WiFi hotspot).
+ * Only the endpoints the Android app needs are declared here.
+ */
+interface PiApi {
+
+    /** GPS fix status — Phase 25.5d */
+    @GET("/api/gps/status")
+    suspend fun getGpsStatus(): GpsStatus
+
+    // Future: add endpoints from android/plan.md as each sub-phase needs them:
+    // @GET("/api/obd/status") — BUG-12 fix
+    // @GET("/api/stats") — Phase 23
+    // @GET("/api/trips") — Phase 18
+    // @GET("/api/trip/{id}") — Phase 18
+    // @GET("/api/dtc") — BUG-03 fix
+    // @GET("/api/local-video/list") — Phase 17
+    // @GET("/api/local-video/file") — Phase 17 (streaming, use @Streaming)
+    // @GET("/api/local-video/thumbnail") — Phase 17
+    // @DELETE("/api/local-video/file") — Phase 17
+    // @GET("/api/remote-config") — Phase 25.5c
+}

android/app/src/main/java/com/yarisobd/app/data/remote/ServerApi.kt

@@ -0,0 +1,23 @@
+package com.yarisobd.app.data.remote
+
+import com.yarisobd.app.data.remote.dto.HealthResponse
+import retrofit2.http.GET
+
+/**
+ * REST API for the remote server (https://yaris.ceaf.dev over cellular/internet).
+ * Only the endpoints the Android app needs are declared here.
+ */
+interface ServerApi {
+
+    /** Health check — Phase 9 (unauthenticated) */
+    @GET("/health")
+    suspend fun health(): HealthResponse
+
+    // Future: add endpoints from android/plan.md as each sub-phase needs them:
+    // @GET("/api/v1/dashcam/upload/status") — Phase 10 chunked upload status
+    // @POST("/api/v1/dashcam/upload/chunk") — Phase 10 multipart chunk upload
+    // @GET("/api/v1/portal/trips") — Phase 24 portal trips (needs auth cookie)
+    // @GET("/api/v1/portal/trip/{id}") — Phase 24
+    // @GET("/api/v1/portal/dashcam") — Phase 24
+    // @GET("/api/v1/portal/dashcam/stream/{id}") — Phase 24 streaming
+}

android/app/src/main/java/com/yarisobd/app/data/remote/dto/GpsStatus.kt

@@ -0,0 +1,15 @@
+package com.yarisobd.app.data.remote.dto
+
+import kotlinx.serialization.Serializable
+
+/**
+ * Response from Pi's GET /api/gps/status (Phase 25.5d).
+ */
+@Serializable
+data class GpsStatus(
+    val thread_alive: Boolean = false,
+    val has_fix: Boolean = false,
+    val latitude: Double? = null,
+    val longitude: Double? = null,
+    val fix_age_seconds: Double? = null,
+)

android/app/src/main/java/com/yarisobd/app/data/remote/dto/HealthResponse.kt

@@ -0,0 +1,11 @@
+package com.yarisobd.app.data.remote.dto
+
+import kotlinx.serialization.Serializable
+
+/**
+ * Response from server's GET /health (Phase 9).
+ */
+@Serializable
+data class HealthResponse(
+    val status: String = "",
+)

android/app/src/main/java/com/yarisobd/app/util/NetworkBinder.kt

@@ -0,0 +1,120 @@
+package com.yarisobd.app.util
+
+import android.content.Context
+import android.net.ConnectivityManager
+import android.net.Network
+import android.net.NetworkCapabilities
+import android.net.NetworkRequest
+import kotlinx.coroutines.suspendCancellableCoroutine
+import okhttp3.Dns
+import okhttp3.OkHttpClient
+import java.net.InetAddress
+import java.net.InetSocketAddress
+import java.net.Proxy
+import java.net.Socket
+import javax.net.SocketFactory
+import kotlin.coroutines.resume
+
+/**
+ * Discovers and binds OkHttp clients to specific Android [Network] objects
+ * for simultaneous WiFi + cellular connectivity.
+ *
+ * This is the core unlock for Phase 28 — the web UI (Phase 11/12) could
+ * never do this because browsers have no access to per-socket network binding.
+ * A native app using [Network.bindSocket] / [Network.socketFactory] can.
+ */
+object NetworkBinder {
+
+    /**
+     * Finds the WiFi network associated with the Pi hotspot ("yaris 911").
+     * Identified by: TRANSPORT_WIFI + NO NET_CAPABILITY_INTERNET
+     * (the Pi hotspot has no internet gateway).
+     */
+    suspend fun findPiHotspotNetwork(context: Context): Network? {
+        val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
+
+        return cm.allNetworks.firstOrNull { network ->
+            val caps = cm.getNetworkCapabilities(network) ?: return@firstOrNull false
+            caps.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) &&
+                !caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
+        }
+    }
+
+    /**
+     * Finds the cellular network.
+     * Identified by: TRANSPORT_CELLULAR + NET_CAPABILITY_INTERNET
+     */
+    suspend fun findCellularNetwork(context: Context): Network? {
+        val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
+
+        return cm.allNetworks.firstOrNull { network ->
+            val caps = cm.getNetworkCapabilities(network) ?: return@firstOrNull false
+            caps.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) &&
+                caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
+        }
+    }
+
+    /**
+     * Returns the current default network (whatever Android picked).
+     * Useful as a fallback when cellular isn't available — the default
+     * network may still route internet traffic.
+     */
+    fun findDefaultNetwork(context: Context): Network? {
+        val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
+        return cm.activeNetwork
+    }
+
+    /**
+     * Creates an OkHttpClient whose sockets are bound to [network].
+     *
+     * Uses [Network.socketFactory] so ALL sockets (including redirects,
+     * connection pooling, DNS) use the specified network interface.
+     * Also overrides DNS resolution through the same network to avoid
+     * leaking DNS queries to the wrong interface.
+     */
+    fun createBoundClient(network: Network): OkHttpClient {
+        return OkHttpClient.Builder()
+            .socketFactory(network.socketFactory)
+            .dns(NetworkDns(network))
+            .proxy(Proxy.NO_PROXY) // Don't use system proxy — may route to wrong network
+            .build()
+    }
+
+    /**
+     * Creates an OkHttpClient for the default (system-chosen) network.
+     */
+    fun createDefaultClient(): OkHttpClient {
+        return OkHttpClient.Builder().build()
+    }
+
+    /**
+     * DNS resolver that uses a specific [Network]'s name resolution.
+     * OkHttp's default Dns uses java.net.InetAddress which goes through
+     * the system default network — this pins DNS to the bound network.
+     */
+    private class NetworkDns(private val network: Network) : Dns {
+        override fun lookup(hostname: String): List<InetAddress> {
+            return network.getAllByName(hostname).toList()
+        }
+    }
+}
+
+/**
+ * Waits for a network with the given [transport] to become available.
+ * Used at app startup to wait for the Pi hotspot to connect before
+ * making API calls.
+ */
+suspend fun ConnectivityManager.awaitNetwork(transport: Int): Network {
+    return suspendCancellableCoroutine { continuation ->
+        val callback = object : ConnectivityManager.NetworkCallback() {
+            override fun onAvailable(network: Network) {
+                continuation.resume(network)
+            }
+        }
+        val request = NetworkRequest.Builder()
+            .addTransportType(transport)
+            .build()
+        registerNetworkCallback(request, callback)
+        continuation.invokeOnCancellation { unregisterNetworkCallback(callback) }
+    }
+}

android/plan.md

@@ -76,29 +76,26 @@ android/
 - [x] Create Android project in `android/` via Android Studio (Empty Activity + Compose)
 - [x] Kotlin DSL build files with version catalog
 - [x] `.gitignore` for Android (`*.iml`, `.gradle/`, `build/`, `local.properties`, `.idea/`)
-- [ ] Verify project builds and runs on emulator (blank screen)
+- [x] Create Android project in `android/` via Android Studio (Empty Activity + Compose)
-- [ ] Commit: `init: android project scaffold`
+- [x] Kotlin DSL build files with version catalog
+- [x] `.gitignore` for Android (`*.iml`, `.gradle/`, `build/`, `local.properties`, `.idea/`)
+- [ ] Verify project builds and runs on emulator (needs Android Studio)
+- [x] Commit: `f1c83a2` init: android project scaffold
 
 #### 28.1.2 — Networking layer
-- [ ] Add dependencies: OkHttp 4.x, Retrofit 2.x, Kotlinx Serialization (or Moshi)
+- [x] Add dependencies: OkHttp 4.12, Retrofit 2.11, Kotlinx Serialization 1.7.3
-- [ ] Create `NetworkBinder.kt` — utility class that:
+- [x] Create `NetworkBinder.kt` — discovers WiFi (Pi hotspot, no-internet) + cellular networks
-  - On startup, discovers available `Network` objects via `ConnectivityManager`
+  via `ConnectivityManager`, creates socket-bound `OkHttpClient` per network
-  - Identifies the WiFi network matching `10.42.0.0/24` (Pi hotspot subnet)
+- [x] Create Retrofit service interfaces (`PiApi.kt`, `ServerApi.kt`) with placeholder endpoints
-  - Identifies the cellular network (`TRANSPORT_CELLULAR`)
+- [x] Create DTOs: `GpsStatus`, `HealthResponse`
-  - Exposes `bindToWifi(): OkHttpClient` and `bindToCellular(): OkHttpClient` factories
+- [x] Wire `DualNetworkTestScreen.kt` with real OkHttp calls + simultaneous "Test Both" button
-  - Falls back gracefully if one network is unavailable
+- [x] Wire `MainActivity.kt` to discover networks at startup and pass bound clients to screen
-- [ ] Create Retrofit service interfaces:
-  - `PiApi.kt` — endpoints on `http://10.42.0.1` (or dynamically resolved)
-  - `ServerApi.kt` — endpoints on `https://yaris.ceaf.dev`
-- [ ] Wire up a manual test screen with two buttons + status text:
-  - "Test Pi" → calls `/api/gps/status` on WiFi-bound client, shows response
-  - "Test Server" → calls `/health` on cellular-bound client, shows response
 - [ ] **Real-device gate test:**
   - Connect phone to Pi hotspot ("yaris 911")
   - Verify cellular data is still active (browse any website while on hotspot)
   - Press "Test Pi" → should return GPS status JSON
   - Press "Test Server" → should return `{"status":"ok"}`
-  - Press both rapidly → both should succeed
+  - Press "Test Both" → both should succeed simultaneously
   - If either fails: investigate `bindProcessToNetwork()` behavior on this Pixel/Android version
 - [ ] Commit: `feat: dual-network proof-of-concept`