fix(security): credential wipe on endpoint change, PairingProbeState gating, and parser hardening

app/src/main/java/app/hermes/mobile/core/pairing/HermesPairingParser.kt

@@ -11,6 +11,10 @@ object HermesPairingParser {
 
     fun parse(rawUri: String): PairingValidationResult {
         try {
+            if (rawUri.toByteArray(Charsets.UTF_8).size > 4096) {
+                return PairingValidationResult.InvalidPayload("URI exceeds maximum length of 4096 bytes")
+            }
+
             val uri = URI(rawUri)
             if (uri.scheme != "hermes" || uri.host != "pair") {
                 return PairingValidationResult.InvalidPayload("Invalid scheme or host")
@@ -29,6 +33,10 @@ object HermesPairingParser {
                 return PairingValidationResult.InvalidPayload("Malformed Base64")
             }
 
+            if (decodedBytes.size > 2048) {
+                return PairingValidationResult.InvalidPayload("Decoded payload exceeds 2048 bytes")
+            }
+
             val jsonString = String(decodedBytes, Charsets.UTF_8)
             val payload = try {
                 json.decodeFromString<HermesPairingPayload>(jsonString)
@@ -43,13 +51,32 @@ object HermesPairingParser {
                 return PairingValidationResult.InvalidPayload("Invalid type")
             }
             try {
-                UUID.fromString(payload.hostId)
+                val uuid = UUID.fromString(payload.hostId)
+                if (uuid.toString() != payload.hostId.lowercase()) {
+                    return PairingValidationResult.InvalidPayload("host_id must be a valid UUID string")
+                }
             } catch (e: IllegalArgumentException) {
                 return PairingValidationResult.InvalidPayload("Invalid host_id")
             }
+            
+            if (payload.name.isBlank()) {
+                return PairingValidationResult.InvalidPayload("Name is empty")
+            }
+            val trimmedName = payload.name.trim()
+            if (trimmedName.length > 128) {
+                return PairingValidationResult.InvalidPayload("Name exceeds 128 characters")
+            }
+            if (payload.name.any { it in '\u0000'..'\u001F' || it in '\u007F'..'\u009F' }) {
+                return PairingValidationResult.InvalidPayload("Name contains control characters")
+            }
+
             if (payload.host.isBlank()) {
                 return PairingValidationResult.InvalidPayload("Host is empty")
             }
+            if (payload.host.any { it.isWhitespace() || it == '/' || it == '\\' || it == '?' || it == '#' || it == '@' || it == ':' || it in '\u0000'..'\u001F' || it in '\u007F'..'\u009F' }) {
+                return PairingValidationResult.InvalidPayload("Host contains invalid characters")
+            }
+
             if (payload.port !in 1..65535) {
                 return PairingValidationResult.InvalidPayload("Invalid port")
             }
@@ -57,9 +84,25 @@ object HermesPairingParser {
                 return PairingValidationResult.InvalidScheme("Scheme must be http or https")
             }
 
-            if (payload.expiresAt <= System.currentTimeMillis() / 1000) {
+            if (payload.nonce.isBlank()) {
+                return PairingValidationResult.InvalidPayload("Nonce is empty")
+            }
+            val nonceBytes = try {
+                Base64.getUrlDecoder().decode(payload.nonce)
+            } catch (e: IllegalArgumentException) {
+                return PairingValidationResult.InvalidPayload("Nonce must be valid Base64URL")
+            }
+            if (nonceBytes.size < 16 || nonceBytes.size > 64) {
+                return PairingValidationResult.InvalidPayload("Nonce must decode to between 16 and 64 bytes")
+            }
+
+            val now = System.currentTimeMillis() / 1000
+            if (payload.expiresAt < now - 30) {
                 return PairingValidationResult.Expired(payload.expiresAt)
             }
+            if (payload.expiresAt > now + 600) {
+                return PairingValidationResult.InvalidPayload("Expiry exceeds maximum TTL of 600 seconds")
+            }
 
             return PairingValidationResult.Success(payload)
         } catch (e: Exception) {

app/src/main/java/app/hermes/mobile/core/pairing/PairingModels.kt

@@ -14,7 +14,34 @@ data class HermesPairingPayload(
     val scheme: String = "http",
     @SerialName("expires_at") val expiresAt: Long,
     val nonce: String
-)
+) {
+    val canonicalEndpoint: CanonicalEndpoint
+        get() = CanonicalEndpoint(
+            scheme = scheme.lowercase(),
+            host = host.lowercase(),
+            port = if (port == 0) {
+                if (scheme.lowercase() == "https") 443 else 80
+            } else port
+        )
+}
+
+data class CanonicalEndpoint(val scheme: String, val host: String, val port: Int) {
+    companion object {
+        fun fromBaseUrl(baseUrl: String): CanonicalEndpoint {
+            return try {
+                val uri = java.net.URI(baseUrl)
+                val scheme = uri.scheme?.lowercase() ?: "http"
+                val host = uri.host?.lowercase() ?: ""
+                val port = if (uri.port == -1 || uri.port == 0) {
+                    if (scheme == "https") 443 else 80
+                } else uri.port
+                CanonicalEndpoint(scheme, host, port)
+            } catch (e: Exception) {
+                CanonicalEndpoint("http", "", 80)
+            }
+        }
+    }
+}
 
 sealed interface PairingValidationResult {
     data class Success(val payload: HermesPairingPayload) : PairingValidationResult

app/src/main/java/app/hermes/mobile/feature/hosts/HostsScreen.kt

@@ -200,10 +200,15 @@ fun HostsScreen(
 
         uiState.scannedPayload?.let { payload ->
             val existingHost = hosts.find { it.id.value == payload.hostId }
+            val isEndpointChanged = existingHost != null && 
+                app.hermes.mobile.core.pairing.CanonicalEndpoint.fromBaseUrl(existingHost.baseUrl) != payload.canonicalEndpoint
+                
             PairingPreviewDialog(
                 payload = payload,
                 isExistingHost = existingHost != null,
                 existingHostName = existingHost?.displayName,
+                isEndpointChanged = isEndpointChanged,
+                oldEndpointUrl = existingHost?.baseUrl,
                 onConfirm = { allowCleartext ->
                     viewModel.confirmPairing(payload, allowCleartext)
                 },

app/src/main/java/app/hermes/mobile/feature/hosts/HostsViewModel.kt

@@ -151,6 +151,11 @@ class HostsViewModel(
         viewModelScope.launch {
             val existingHost = connectionManager.hostDao.getHost(payload.hostId)
             val hostToConnect = if (existingHost != null) {
+                val oldCanonical = app.hermes.mobile.core.pairing.CanonicalEndpoint.fromBaseUrl(existingHost.baseUrl)
+                if (oldCanonical != payload.canonicalEndpoint) {
+                    connectionManager.disconnectHost(HermesHostId(payload.hostId))
+                    tokenVault.clearTokens(payload.hostId)
+                }
                 val updatedHost = HermesHost(
                     id = HermesHostId(payload.hostId),
                     displayName = payload.name,

app/src/main/java/app/hermes/mobile/feature/hosts/PairingPreviewDialog.kt

@@ -7,9 +7,18 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import app.hermes.mobile.core.pairing.HermesPairingPayload
 import app.hermes.mobile.core.network.HermesRestClient
+import app.hermes.mobile.core.model.HermesServerStatus
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
+import java.net.URI
+
+sealed interface PairingProbeState {
+    data object Idle : PairingProbeState
+    data object Probing : PairingProbeState
+    data class Success(val status: HermesServerStatus) : PairingProbeState
+    data class Failed(val message: String) : PairingProbeState
+}
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
@@ -17,15 +26,18 @@ fun PairingPreviewDialog(
     payload: HermesPairingPayload,
     isExistingHost: Boolean,
     existingHostName: String?,
+    isEndpointChanged: Boolean,
+    oldEndpointUrl: String?,
     onConfirm: (Boolean) -> Unit,
     onCancel: () -> Unit
 ) {
-    var probeStatus by remember { mutableStateOf("Probing...") }
+    var probeState by remember { mutableStateOf<PairingProbeState>(PairingProbeState.Probing) }
     var allowCleartext by remember { mutableStateOf(payload.scheme == "http") }
     val coroutineScope = rememberCoroutineScope()
     val restClient = remember { HermesRestClient() }
 
-    LaunchedEffect(payload) {
+    fun doProbe() {
+        probeState = PairingProbeState.Probing
         coroutineScope.launch {
             try {
                 val url = "${payload.scheme}://${payload.host}:${payload.port}"
@@ -35,17 +47,23 @@ fun PairingPreviewDialog(
                 if (result.isSuccess) {
                     val status = result.getOrNull()
                     if (status != null) {
-                        probeStatus = "Hermes v${status.version} | Auth: ${if (status.authRequired) "Required" else "None"}"
+                        probeState = PairingProbeState.Success(status)
+                    } else {
+                        probeState = PairingProbeState.Failed("Empty status")
                     }
                 } else {
-                    probeStatus = "Probe failed: ${result.exceptionOrNull()?.message}"
+                    probeState = PairingProbeState.Failed(result.exceptionOrNull()?.message ?: "Unknown error")
                 }
             } catch (e: Exception) {
-                probeStatus = "Probe failed: ${e.message}"
+                probeState = PairingProbeState.Failed(e.message ?: "Unknown error")
             }
         }
     }
 
+    LaunchedEffect(payload) {
+        doProbe()
+    }
+
     AlertDialog(
         onDismissRequest = onCancel,
         title = { Text("Pairing Preview") },
@@ -54,20 +72,61 @@ fun PairingPreviewDialog(
                 Text("Host: ${payload.name}", style = MaterialTheme.typography.bodyLarge)
                 Text("Address: ${payload.scheme}://${payload.host}:${payload.port}", style = MaterialTheme.typography.bodyMedium)
                 Spacer(modifier = Modifier.height(8.dp))
-                
-                Text("Status: $probeStatus", style = MaterialTheme.typography.bodySmall)
-                
+
+                when (val state = probeState) {
+                    is PairingProbeState.Probing -> {
+                        Row(verticalAlignment = androidx.compose.ui.Alignment.CenterVertically) {
+                            CircularProgressIndicator(modifier = Modifier.size(16.dp), strokeWidth = 2.dp)
+                            Spacer(modifier = Modifier.width(8.dp))
+                            Text("Probing status...", style = MaterialTheme.typography.bodySmall)
+                        }
+                    }
+                    is PairingProbeState.Failed -> {
+                        Surface(color = MaterialTheme.colorScheme.errorContainer, shape = MaterialTheme.shapes.small) {
+                            Column(modifier = Modifier.padding(8.dp)) {
+                                Text("Probe failed: ${state.message}", style = MaterialTheme.typography.bodySmall, color = MaterialTheme.colorScheme.onErrorContainer)
+                                Spacer(modifier = Modifier.height(4.dp))
+                                Button(onClick = { doProbe() }, modifier = Modifier.height(32.dp), contentPadding = PaddingValues(horizontal = 8.dp, vertical = 0.dp)) {
+                                    Text("Retry", style = MaterialTheme.typography.labelSmall)
+                                }
+                            }
+                        }
+                    }
+                    is PairingProbeState.Success -> {
+                        Surface(color = androidx.compose.ui.graphics.Color(0xFFD1FAE5), shape = MaterialTheme.shapes.small) {
+                            Text(
+                                "Hermes v${state.status.version} | Auth: ${if (state.status.authRequired) "Required" else "None"}",
+                                modifier = Modifier.padding(8.dp),
+                                style = MaterialTheme.typography.bodySmall,
+                                color = androidx.compose.ui.graphics.Color(0xFF065F46)
+                            )
+                        }
+                    }
+                    PairingProbeState.Idle -> {}
+                }
+
                 if (isExistingHost) {
                     Spacer(modifier = Modifier.height(8.dp))
-                    Surface(color = MaterialTheme.colorScheme.secondaryContainer, shape = MaterialTheme.shapes.small) {
-                        Text(
-                            "Will update endpoint for existing host '${existingHostName ?: payload.name}'",
-                            modifier = Modifier.padding(8.dp),
-                            style = MaterialTheme.typography.labelMedium
-                        )
+                    if (isEndpointChanged) {
+                        Surface(color = MaterialTheme.colorScheme.errorContainer, shape = MaterialTheme.shapes.small) {
+                            Text(
+                                "Endpoint for this host has changed from $oldEndpointUrl to ${payload.scheme}://${payload.host}:${payload.port}. For security, saved login credentials will be cleared. Fresh login will be required.",
+                                modifier = Modifier.padding(8.dp),
+                                style = MaterialTheme.typography.labelMedium,
+                                color = MaterialTheme.colorScheme.onErrorContainer
+                            )
+                        }
+                    } else {
+                        Surface(color = MaterialTheme.colorScheme.secondaryContainer, shape = MaterialTheme.shapes.small) {
+                            Text(
+                                "Will update endpoint for existing host '${existingHostName ?: payload.name}'",
+                                modifier = Modifier.padding(8.dp),
+                                style = MaterialTheme.typography.labelMedium
+                            )
+                        }
                     }
                 }
-                
+
                 if (payload.scheme == "http") {
                     Spacer(modifier = Modifier.height(8.dp))
                     Row(
@@ -88,7 +147,10 @@ fun PairingPreviewDialog(
             }
         },
         confirmButton = {
-            TextButton(onClick = { onConfirm(allowCleartext) }) {
+            Button(
+                onClick = { onConfirm(allowCleartext) },
+                enabled = probeState is PairingProbeState.Success
+            ) {
                 Text(if (isExistingHost) "Update Host" else "Add Host")
             }
         },

app/src/test/java/app/hermes/mobile/core/network/JsonRpcGatewayClientTest.kt

@@ -95,7 +95,12 @@ class JsonRpcGatewayClientTest {
         client.connect(wsUrl, allowCleartext = true)
 
         // Give WS a moment to open transport
-        kotlinx.coroutines.delay(100)
+        var retries = 0
+        while (serverWebSocket == null && retries < 50) {
+            kotlinx.coroutines.delay(50)
+            retries++
+        }
+        
         // Must still be Connecting before gateway.ready is received
         assertEquals(ConnectionState.Connecting, client.connectionState.value)
 

app/src/test/java/app/hermes/mobile/core/pairing/HermesPairingParserTest.kt

@@ -14,7 +14,7 @@ class HermesPairingParserTest {
 
     @Test
     fun testValidPairingPayloadParsing() {
-        val futureTime = (System.currentTimeMillis() / 1000) + 3600
+        val futureTime = (System.currentTimeMillis() / 1000) + 300
         val hostId = UUID.randomUUID().toString()
         val json = """
             {
@@ -26,7 +26,7 @@ class HermesPairingParserTest {
                 "port": 9119,
                 "scheme": "http",
                 "expires_at": $futureTime,
-                "nonce": "random-nonce"
+                "nonce": "QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"
             }
         """.trimIndent()
         
@@ -44,128 +44,127 @@ class HermesPairingParserTest {
     }
 
     @Test
-    fun testExpiredPayloadRejection() {
-        val pastTime = (System.currentTimeMillis() / 1000) - 3600
-        val hostId = UUID.randomUUID().toString()
+    fun testCanonicalCrossContractFixture() {
+        val futureTime = (System.currentTimeMillis() / 1000) + 300
         val json = """
             {
                 "v": 1,
                 "type": "hermes-pair",
-                "host_id": "$hostId",
-                "name": "My Server",
-                "host": "192.168.1.5",
+                "host_id": "58af1471-a0a2-4e2b-9426-5068f2a2deab",
+                "name": "Office-PC",
+                "host": "192.168.1.150",
                 "port": 9119,
                 "scheme": "http",
-                "expires_at": $pastTime,
-                "nonce": "random-nonce"
+                "expires_at": $futureTime,
+                "nonce": "QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"
             }
         """.trimIndent()
-        
         val uri = "hermes://pair?data=${encodePayload(json)}"
         val result = HermesPairingParser.parse(uri)
-        
+        assertTrue(result is PairingValidationResult.Success)
+        val payload = (result as PairingValidationResult.Success).payload
+        assertEquals("58af1471-a0a2-4e2b-9426-5068f2a2deab", payload.hostId)
+        assertEquals("Office-PC", payload.name)
+        assertEquals("192.168.1.150", payload.host)
+        assertEquals(9119, payload.port)
+        assertEquals("http", payload.scheme)
+        assertEquals("QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY", payload.nonce)
+    }
+
+    @Test
+    fun testExpiredPayloadRejection() {
+        val pastTime = (System.currentTimeMillis() / 1000) - 35
+        val json = """{"v":1,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"S","host":"1.1.1.1","port":9119,"scheme":"http","expires_at":$pastTime,"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
+        val uri = "hermes://pair?data=${encodePayload(json)}"
+        val result = HermesPairingParser.parse(uri)
         assertTrue(result is PairingValidationResult.Expired)
     }
 
+    @Test
+    fun testExcessiveTTLRejection() {
+        val farFuture = (System.currentTimeMillis() / 1000) + 605
+        val json = """{"v":1,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"S","host":"1.1.1.1","port":9119,"scheme":"http","expires_at":$farFuture,"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
+        val result = HermesPairingParser.parse("hermes://pair?data=${encodePayload(json)}")
+        assertTrue(result is PairingValidationResult.InvalidPayload)
+    }
+
     @Test
     fun testInvalidVersionRejection() {
-        val futureTime = (System.currentTimeMillis() / 1000) + 3600
-        val hostId = UUID.randomUUID().toString()
-        val json = """
-            {
-                "v": 2,
-                "type": "hermes-pair",
-                "host_id": "$hostId",
-                "name": "My Server",
-                "host": "192.168.1.5",
-                "port": 9119,
-                "scheme": "http",
-                "expires_at": $futureTime,
-                "nonce": "random-nonce"
-            }
-        """.trimIndent()
+        val json = """{"v":2,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"S","host":"1.1.1.1","port":9119,"scheme":"http","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
+        assertTrue(HermesPairingParser.parse("hermes://pair?data=${encodePayload(json)}") is PairingValidationResult.InvalidVersion)
+    }
+
+    @Test
+    fun testInvalidTypeRejection() {
+        val json = """{"v":1,"type":"other","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"S","host":"1.1.1.1","port":9119,"scheme":"http","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
+        assertTrue(HermesPairingParser.parse("hermes://pair?data=${encodePayload(json)}") is PairingValidationResult.InvalidPayload)
+    }
+
+    @Test
+    fun testInvalidHostIdRejection() {
+        val json = """{"v":1,"type":"hermes-pair","host_id":"not-a-uuid","name":"S","host":"1.1.1.1","port":9119,"scheme":"http","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
+        assertTrue(HermesPairingParser.parse("hermes://pair?data=${encodePayload(json)}") is PairingValidationResult.InvalidPayload)
+    }
+
+    @Test
+    fun testInvalidNameRejections() {
+        val futures = listOf("", "   ", "Name\u0000", "A".repeat(129))
+        futures.forEach { name ->
+            val json = """{"v":1,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"$name","host":"1.1.1.1","port":9119,"scheme":"http","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
+            assertTrue(HermesPairingParser.parse("hermes://pair?data=${encodePayload(json)}") is PairingValidationResult.InvalidPayload)
+        }
+    }
+
+    @Test
+    fun testInvalidHostRejections() {
+        val hosts = listOf("1.1.1.1/path", "user@1.1.1.1", "1.1.1.1:9119", "1.1.1.1?q=1", "1.1.1.1#frag", "1 1")
+        hosts.forEach { host ->
+            val json = """{"v":1,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"S","host":"$host","port":9119,"scheme":"http","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
+            assertTrue(HermesPairingParser.parse("hermes://pair?data=${encodePayload(json)}") is PairingValidationResult.InvalidPayload)
+        }
+    }
+
+    @Test
+    fun testInvalidPortRejections() {
+        val ports = listOf(0, 70000)
+        ports.forEach { port ->
+            val json = """{"v":1,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"S","host":"1.1.1.1","port":$port,"scheme":"http","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
+            assertTrue(HermesPairingParser.parse("hermes://pair?data=${encodePayload(json)}") is PairingValidationResult.InvalidPayload)
+        }
+    }
+
+    @Test
+    fun testInvalidSchemeRejection() {
+        val json = """{"v":1,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"S","host":"1.1.1.1","port":9119,"scheme":"ftp","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
+        assertTrue(HermesPairingParser.parse("hermes://pair?data=${encodePayload(json)}") is PairingValidationResult.InvalidScheme)
+    }
+
+    @Test
+    fun testInvalidNonceRejections() {
+        val shortNonce = Base64.getUrlEncoder().withoutPadding().encodeToString("12345".toByteArray())
+        val json = """{"v":1,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"S","host":"1.1.1.1","port":9119,"scheme":"http","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"$shortNonce"}"""
+        assertTrue(HermesPairingParser.parse("hermes://pair?data=${encodePayload(json)}") is PairingValidationResult.InvalidPayload)
         
+        val invalidBase64 = "ThisIs!Not!Valid!Base64"
+        val json2 = """{"v":1,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"S","host":"1.1.1.1","port":9119,"scheme":"http","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"$invalidBase64"}"""
+        assertTrue(HermesPairingParser.parse("hermes://pair?data=${encodePayload(json2)}") is PairingValidationResult.InvalidPayload)
+    }
+
+    @Test
+    fun testOversizedPayloads() {
+        val longString = "A".repeat(3000)
+        val json = """{"v":1,"type":"hermes-pair","host_id":"58af1471-a0a2-4e2b-9426-5068f2a2deab","name":"$longString","host":"1.1.1.1","port":9119,"scheme":"http","expires_at":${(System.currentTimeMillis() / 1000) + 300},"nonce":"QUJDREVGR0hJSktMTU5PUHFyc3R1dnd4eXoxMjM0NTY"}"""
         val uri = "hermes://pair?data=${encodePayload(json)}"
-        val result = HermesPairingParser.parse(uri)
+        assertTrue(HermesPairingParser.parse(uri) is PairingValidationResult.InvalidPayload)
         
-        assertTrue(result is PairingValidationResult.InvalidVersion)
+        val hugeUri = "hermes://pair?data=" + "A".repeat(5000)
+        assertTrue(HermesPairingParser.parse(hugeUri) is PairingValidationResult.InvalidPayload)
     }
 
     @Test
     fun testMalformedBase64Rejection() {
         val uri = "hermes://pair?data=ThisIs!Not!Valid!Base64"
         val result = HermesPairingParser.parse(uri)
-        
-        assertTrue(result is PairingValidationResult.InvalidPayload)
-    }
-
-    @Test
-    fun testInvalidPortRejection() {
-        val futureTime = (System.currentTimeMillis() / 1000) + 3600
-        val hostId = UUID.randomUUID().toString()
-        val json = """
-            {
-                "v": 1,
-                "type": "hermes-pair",
-                "host_id": "$hostId",
-                "name": "My Server",
-                "host": "192.168.1.5",
-                "port": 70000,
-                "scheme": "http",
-                "expires_at": $futureTime,
-                "nonce": "random-nonce"
-            }
-        """.trimIndent()
-        
-        val uri = "hermes://pair?data=${encodePayload(json)}"
-        val result = HermesPairingParser.parse(uri)
-        
-        assertTrue(result is PairingValidationResult.InvalidPayload)
-    }
-
-    @Test
-    fun testInvalidSchemeRejection() {
-        val futureTime = (System.currentTimeMillis() / 1000) + 3600
-        val hostId = UUID.randomUUID().toString()
-        val json = """
-            {
-                "v": 1,
-                "type": "hermes-pair",
-                "host_id": "$hostId",
-                "name": "My Server",
-                "host": "192.168.1.5",
-                "port": 9119,
-                "scheme": "ftp",
-                "expires_at": $futureTime,
-                "nonce": "random-nonce"
-            }
-        """.trimIndent()
-        
-        val uri = "hermes://pair?data=${encodePayload(json)}"
-        val result = HermesPairingParser.parse(uri)
-        
-        assertTrue(result is PairingValidationResult.InvalidScheme)
-    }
-
-    @Test
-    fun testMissingHostIdRejection() {
-        val futureTime = (System.currentTimeMillis() / 1000) + 3600
-        val json = """
-            {
-                "v": 1,
-                "type": "hermes-pair",
-                "name": "My Server",
-                "host": "192.168.1.5",
-                "port": 9119,
-                "scheme": "http",
-                "expires_at": $futureTime,
-                "nonce": "random-nonce"
-            }
-        """.trimIndent()
-        
-        val uri = "hermes://pair?data=${encodePayload(json)}"
-        val result = HermesPairingParser.parse(uri)
-        
         assertTrue(result is PairingValidationResult.InvalidPayload)
     }
 }

app/src/test/java/app/hermes/mobile/feature/hosts/HostsPairingTest.kt

@@ -125,7 +125,41 @@ class HostsPairingTest {
 
     @Test
     fun testExistingTokensPreservedOnHostUpdate() = runTest {
-        // Just verify updateHost is called and tokenVault clear isn't.
+        val hostId = UUID.randomUUID().toString()
+        val existingEntity = HostEntity(
+            id = hostId,
+            displayName = "Old Name",
+            baseUrl = "http://192.168.1.5:9119",
+            allowCleartext = true,
+            enabled = true,
+            lastSeenAt = 1000L,
+            lastKnownStatus = "OFFLINE"
+        )
+        
+        val payload = HermesPairingPayload(
+            v = 1,
+            type = "hermes-pair",
+            hostId = hostId,
+            name = "Updated Server Name",
+            host = "192.168.1.5",
+            port = 9119,
+            scheme = "http",
+            expiresAt = (System.currentTimeMillis() / 1000) + 3600,
+            nonce = "nonce"
+        )
+        
+        coEvery { hostDao.getHost(hostId) } returns existingEntity
+        coEvery { connectionManager.updateHost(any()) } returns Unit
+        coEvery { connectionManager.connectHost(any()) } returns Result.success(Unit)
+        
+        viewModel.confirmPairing(payload, allowCleartext = true)
+        
+        coVerify(exactly = 0) { tokenVault.clearTokens(any()) }
+        coVerify(exactly = 0) { connectionManager.disconnectHost(any()) }
+    }
+
+    @Test
+    fun testExistingTokensClearedOnEndpointChange() = runTest {
         val hostId = UUID.randomUUID().toString()
         val existingEntity = HostEntity(
             id = hostId,
@@ -150,9 +184,12 @@ class HostsPairingTest {
         )
         
         coEvery { hostDao.getHost(hostId) } returns existingEntity
+        coEvery { connectionManager.updateHost(any()) } returns Unit
+        coEvery { connectionManager.connectHost(any()) } returns Result.success(Unit)
         
         viewModel.confirmPairing(payload, allowCleartext = true)
         
-        coVerify(exactly = 0) { tokenVault.clearTokens(any()) }
+        coVerify { tokenVault.clearTokens(hostId) }
+        coVerify { connectionManager.disconnectHost(app.hermes.mobile.core.model.HermesHostId(hostId)) }
     }
 }