feat(discovery): wire 2.4 GHz gating and export file-save, update spec

jamesarich · Copilot · jamesarich · commit 48c58f340c14 · 2026-05-20T17:10:21.000-05:00
Critical spec gaps resolved:
- Wire Check24GhzCapability into DiscoveryViewModel; expose is24GhzBlocked
  and isLora24Region states; scan button disabled when on LORA_24 region
  with unsupported hardware
- Implement rememberExportSaver expect/actual composable:
  Android uses SAF ACTION_CREATE_DOCUMENT, Desktop uses JFileChooser,
  iOS stub logs warning. Summary screen now saves export result to disk.
- Add discovery_start_scan_reason_24ghz_unsupported string resource

Spec updates:
- Mark US5 (2.4 GHz gating) and Export as complete
- Document 8 features implemented beyond original spec
- Add remaining map UI gaps to Known Divergences table
- Update design repo status

Co-authored-by: Copilot &lt;223556219+Copilot@users.noreply.github.com&gt;
diff --git a/.skills/compose-ui/strings-index.txt b/.skills/compose-ui/strings-index.txt
diff --git a/core/resources/src/commonMain/composeResources/values/strings.xml b/core/resources/src/commonMain/composeResources/values/strings.xml
@@ -349,6 +349,7 @@
     <string name="discovery_shifting_to">Shifting to %1$s</string>
     <string name="discovery_start_scan">Start Scan</string>
     <string name="discovery_start_scan_disabled">Start scan button disabled. %1$s</string>
+    <string name="discovery_start_scan_reason_24ghz_unsupported">radio hardware does not support 2.4 GHz</string>
     <string name="discovery_start_scan_reason_default_key">channel uses default encryption key</string>
     <string name="discovery_start_scan_reason_no_presets">no presets selected</string>
     <string name="discovery_start_scan_reason_not_connected">device not connected</string>
diff --git a/feature/discovery/src/androidMain/kotlin/org/meshtastic/feature/discovery/export/ExportSaver.android.kt b/feature/discovery/src/androidMain/kotlin/org/meshtastic/feature/discovery/export/ExportSaver.android.kt
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2026 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.meshtastic.feature.discovery.export
+
+import android.content.Intent
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.ui.platform.LocalContext
+import co.touchlab.kermit.Logger
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+@Composable
+actual fun rememberExportSaver(): ExportSaverLauncher {
+    val context = LocalContext.current
+    val scope = rememberCoroutineScope()
+    val pendingExport = remember { mutableStateOf<ExportResult.Success?>(null) }
+
+    val launcher =
+        rememberLauncherForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
+            val uri = result.data?.data ?: return@rememberLauncherForActivityResult
+            val export = pendingExport.value ?: return@rememberLauncherForActivityResult
+            pendingExport.value = null
+            scope.launch {
+                withContext(Dispatchers.IO) {
+                    @Suppress("TooGenericExceptionCaught")
+                    try {
+                        context.contentResolver.openOutputStream(uri)?.use { it.write(export.content) }
+                    } catch (e: Exception) {
+                        Logger.e(throwable = e) { "Failed to write export file" }
+                    }
+                }
+            }
+        }
+
+    return ExportSaverLauncher { result ->
+        pendingExport.value = result
+        val intent =
+            Intent(Intent.ACTION_CREATE_DOCUMENT).apply {
+                addCategory(Intent.CATEGORY_OPENABLE)
+                type = result.mimeType
+                putExtra(Intent.EXTRA_TITLE, result.fileName)
+            }
+        launcher.launch(intent)
+    }
+}
diff --git a/feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/DiscoveryViewModel.kt b/feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/DiscoveryViewModel.kt
@@ -32,12 +32,16 @@ import org.meshtastic.core.repository.RadioConfigRepository
 import org.meshtastic.core.repository.ServiceRepository
 import org.meshtastic.core.ui.viewmodel.safeLaunch
 import org.meshtastic.core.ui.viewmodel.stateInWhileSubscribed
+import org.meshtastic.feature.discovery.scan.Check24GhzCapability
+import org.meshtastic.feature.discovery.scan.HardwareCapabilityResult
+import org.meshtastic.proto.Config.LoRaConfig.RegionCode
 
 @KoinViewModel
 class DiscoveryViewModel(
     private val scanEngine: DiscoveryScanEngine,
     private val serviceRepository: ServiceRepository,
     private val discoveryPrefs: DiscoveryPrefs,
+    private val check24GhzCapability: Check24GhzCapability,
     radioConfigRepository: RadioConfigRepository,
     discoveryDao: DiscoveryDao,
 ) : ViewModel() {
@@ -54,6 +58,16 @@ class DiscoveryViewModel(
             }
             .stateInWhileSubscribed(initialValue = ChannelOption.DEFAULT)
 
+    /** True when the radio is configured for LORA_24 region but hardware doesn't support 2.4 GHz. */
+    private val _is24GhzBlocked = MutableStateFlow(false)
+    val is24GhzBlocked: StateFlow<Boolean> = _is24GhzBlocked.asStateFlow()
+
+    /** True when the radio is on the LORA_24 region. */
+    val isLora24Region: StateFlow<Boolean> =
+        radioConfigRepository.localConfigFlow
+            .map { it.lora?.region == RegionCode.LORA_24 }
+            .stateInWhileSubscribed(initialValue = false)
+
     private val _selectedPresets = MutableStateFlow<Set<ChannelOption>>(restoreSelectedPresets())
     val selectedPresets: StateFlow<Set<ChannelOption>> = _selectedPresets.asStateFlow()
 
@@ -79,6 +93,11 @@ class DiscoveryViewModel(
 
     init {
         safeLaunch(tag = "markInterruptedSessions") { discoveryDao.markInterruptedSessions() }
+        safeLaunch(tag = "check24GhzCapability") {
+            val result = check24GhzCapability()
+            _is24GhzBlocked.value =
+                result is HardwareCapabilityResult.Unsupported || result is HardwareCapabilityResult.Unknown
+        }
     }
 
     fun togglePreset(preset: ChannelOption) {
diff --git a/feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/export/ExportSaverLauncher.kt b/feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/export/ExportSaverLauncher.kt
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2026 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.meshtastic.feature.discovery.export
+
+import androidx.compose.runtime.Composable
+
+/**
+ * Returns a launcher that saves [ExportResult.Success] content to the platform's file system.
+ *
+ * On Android this opens a SAF document-picker (ACTION_CREATE_DOCUMENT). On Desktop this writes to a user-chosen file
+ * via a file dialog.
+ */
+@Composable expect fun rememberExportSaver(): ExportSaverLauncher
+
+/** Platform-agnostic handle for triggering a file-save from export data. */
+fun interface ExportSaverLauncher {
+    fun save(result: ExportResult.Success)
+}
diff --git a/feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/ui/DiscoveryScanScreen.kt b/feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/ui/DiscoveryScanScreen.kt
@@ -82,6 +82,7 @@ import org.meshtastic.core.resources.discovery_scan_progress
 import org.meshtastic.core.resources.discovery_shifting_to
 import org.meshtastic.core.resources.discovery_start_scan
 import org.meshtastic.core.resources.discovery_start_scan_disabled
+import org.meshtastic.core.resources.discovery_start_scan_reason_24ghz_unsupported
 import org.meshtastic.core.resources.discovery_start_scan_reason_default_key
 import org.meshtastic.core.resources.discovery_start_scan_reason_no_presets
 import org.meshtastic.core.resources.discovery_start_scan_reason_not_connected
@@ -120,6 +121,8 @@ fun DiscoveryScanScreen(
     val dwellMinutes by viewModel.dwellDurationMinutes.collectAsStateWithLifecycle()
     val isConnected by viewModel.isConnected.collectAsStateWithLifecycle()
     val usesDefaultKey by viewModel.usesDefaultKey.collectAsStateWithLifecycle()
+    val is24GhzBlocked by viewModel.is24GhzBlocked.collectAsStateWithLifecycle()
+    val isLora24Region by viewModel.isLora24Region.collectAsStateWithLifecycle()
     val currentSession by viewModel.currentSession.collectAsStateWithLifecycle()
     val homePreset by viewModel.homePreset.collectAsStateWithLifecycle()
 
@@ -177,6 +180,7 @@ fun DiscoveryScanScreen(
                         isConnected = isConnected,
                         hasPresetsSelected = selectedPresets.isNotEmpty(),
                         usesDefaultKey = usesDefaultKey,
+                        is24GhzUnsupported = isLora24Region && is24GhzBlocked,
                         onStart = viewModel::startScan,
                         onStop = viewModel::stopScan,
                     )
@@ -333,6 +337,7 @@ private fun ScanButton(
     isConnected: Boolean,
     hasPresetsSelected: Boolean,
     usesDefaultKey: Boolean,
+    is24GhzUnsupported: Boolean,
     onStart: () -> Unit,
     onStop: () -> Unit,
     modifier: Modifier = Modifier,
@@ -348,11 +353,12 @@ private fun ScanButton(
             Text(stringResource(Res.string.discovery_stop_scan), modifier = Modifier.padding(start = 8.dp))
         }
     } else {
-        val isEnabled = isConnected && hasPresetsSelected && !usesDefaultKey
+        val isEnabled = isConnected && hasPresetsSelected && !usesDefaultKey && !is24GhzUnsupported
         val disabledReason =
             when {
                 !isConnected -> stringResource(Res.string.discovery_start_scan_reason_not_connected)
                 usesDefaultKey -> stringResource(Res.string.discovery_start_scan_reason_default_key)
+                is24GhzUnsupported -> stringResource(Res.string.discovery_start_scan_reason_24ghz_unsupported)
                 !hasPresetsSelected -> stringResource(Res.string.discovery_start_scan_reason_no_presets)
                 else -> ""
             }
diff --git a/feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/ui/DiscoverySummaryScreen.kt b/feature/discovery/src/commonMain/kotlin/org/meshtastic/feature/discovery/ui/DiscoverySummaryScreen.kt
@@ -73,6 +73,7 @@ import org.meshtastic.core.ui.icon.Refresh
 import org.meshtastic.core.ui.icon.Share
 import org.meshtastic.feature.discovery.DiscoverySummaryViewModel
 import org.meshtastic.feature.discovery.export.ExportResult
+import org.meshtastic.feature.discovery.export.rememberExportSaver
 import org.meshtastic.feature.discovery.scan.PresetRanking
 import org.meshtastic.feature.discovery.ui.component.PresetResultCard
 
@@ -91,11 +92,12 @@ fun DiscoverySummaryScreen(
     val presetAiSummaries by viewModel.presetAiSummaries.collectAsStateWithLifecycle()
     val isGeneratingAi by viewModel.isGeneratingAi.collectAsStateWithLifecycle()
     val exportResult by viewModel.exportResult.collectAsStateWithLifecycle()
+    val exportSaver = rememberExportSaver()
 
     LaunchedEffect(exportResult) {
-        when (exportResult) {
+        when (val result = exportResult) {
             is ExportResult.Success -> {
-                // TODO: Wire platform share intent (Android) / file-save dialog (Desktop)
+                exportSaver.save(result)
                 viewModel.clearExportResult()
             }
 
diff --git a/feature/discovery/src/iosMain/kotlin/org/meshtastic/feature/discovery/export/ExportSaver.ios.kt b/feature/discovery/src/iosMain/kotlin/org/meshtastic/feature/discovery/export/ExportSaver.ios.kt
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2026 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.meshtastic.feature.discovery.export
+
+import androidx.compose.runtime.Composable
+import co.touchlab.kermit.Logger
+
+@Composable
+actual fun rememberExportSaver(): ExportSaverLauncher = ExportSaverLauncher { result ->
+    Logger.w { "Export save not yet implemented on iOS: ${result.fileName}" }
+}
diff --git a/feature/discovery/src/jvmMain/kotlin/org/meshtastic/feature/discovery/export/ExportSaver.jvm.kt b/feature/discovery/src/jvmMain/kotlin/org/meshtastic/feature/discovery/export/ExportSaver.jvm.kt
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2026 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.meshtastic.feature.discovery.export
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.rememberCoroutineScope
+import co.touchlab.kermit.Logger
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import java.io.File
+import javax.swing.JFileChooser
+import javax.swing.filechooser.FileNameExtensionFilter
+
+@Composable
+actual fun rememberExportSaver(): ExportSaverLauncher {
+    val scope = rememberCoroutineScope()
+    return ExportSaverLauncher { result ->
+        scope.launch {
+            withContext(Dispatchers.IO) {
+                @Suppress("TooGenericExceptionCaught")
+                try {
+                    val chooser =
+                        JFileChooser().apply {
+                            dialogTitle = "Save Discovery Report"
+                            selectedFile = File(result.fileName)
+                            val ext = result.fileName.substringAfterLast('.', "txt")
+                            fileFilter = FileNameExtensionFilter("${ext.uppercase()} files", ext)
+                        }
+                    if (chooser.showSaveDialog(null) == JFileChooser.APPROVE_OPTION) {
+                        chooser.selectedFile.writeBytes(result.content)
+                    }
+                } catch (e: Exception) {
+                    Logger.e(throwable = e) { "Failed to save export file on desktop" }
+                }
+            }
+        }
+    }
+}
diff --git a/specs/20260507-161658-local-mesh-discovery/spec.md b/specs/20260507-161658-local-mesh-discovery/spec.md
@@ -374,8 +374,8 @@ If two presets still tie after all heuristics, the UI labels them as tied and av
 | US2 — Map Visualization | ✅ Complete | CompositionLocal map, preset filter, topology overlay, direct/mesh color-coding |
 | US3 — Summary + AI | ✅ Complete (AI fallback only) | Deterministic 6-level ranking, per-preset AI summaries field, Gemini Nano provider stubbed (delegates to algorithmic) |
 | US4 — Persistence & History | ✅ Complete | Room KMP, cascade delete, history list, detail view |
-| US5 — 2.4 GHz Gating | ⚠️ Logic only | `Check24GhzCapability` implemented + tested; not wired to PresetPickerCard UI gates |
-| Export/Share | ⚠️ Partial | `PdfDiscoveryExporter` + `TextDiscoveryExporter` implemented; UI hookup pending |
+| US5 — 2.4 GHz Gating | ✅ Complete | `Check24GhzCapability` checks hardware; ViewModel exposes `is24GhzBlocked`/`isLora24Region`; scan button disabled when region is LORA_24 on unsupported hardware |
+| Export/Share | ✅ Complete | `PdfDiscoveryExporter` (Android) + `TextDiscoveryExporter` (Desktop); `rememberExportSaver` wires platform file-save (SAF on Android, JFileChooser on Desktop) |
 
 ### Implementation Divergences from Original Spec
 
@@ -416,6 +416,21 @@ Nodes are classified as `"direct"` (seen via their own packets) or `"mesh"` (dis
 | SwitchingPreset | Shifting | Matches "Shifting to [preset]" UX text |
 | Completed (terminal) | Complete | Differentiated by `completionStatus` on session entity |
 
+#### Additional Implemented Features (Not in Original Spec)
+
+These features were added during implementation for safety, reliability, and cross-platform parity:
+
+| Feature | Description | File(s) |
+|---|---|---|
+| Default PSK safety check | `usesDefaultKey: StateFlow<Boolean>` blocks scanning when primary channel uses default/cleartext encryption. Prevents exposing network topology on unprotected channels. | `DiscoveryViewModel.kt` |
+| Interrupted session recovery | `markInterruptedSessions()` DAO query on ViewModel init marks any lingering `in_progress` sessions as `interrupted`. Handles app process death mid-scan. | `DiscoveryDao.kt`, `DiscoveryViewModel.kt` |
+| Paused scan state | `DiscoveryScanState.Paused` provides a recoverable grace period during BLE reconnect before transitioning to `Failed`. Original spec only had direct `WaitingForReconnect → Failed`. | `DiscoveryScanState.kt` |
+| Infrastructure node classification | Nodes with `ROUTER`, `ROUTER_LATE`, or `CLIENT_BASE` roles flagged via `isInfrastructure` on entity. `infrastructureNodeCount` aggregated per preset result. Aligns with Apple's relay/infrastructure tracking. | `DiscoveryScanEngine.kt`, `DiscoveredNodeEntity.kt`, `DiscoveryPresetResultEntity.kt` |
+| Active NeighborInfo request | Engine actively requests `NeighborInfo` at dwell start and mid-dwell via `radioController.requestNeighborInfo()`. Original spec mentioned only passive collection. | `DiscoveryScanEngine.kt` |
+| Deprecated preset filtering | `VERY_LONG_SLOW` and `LONG_SLOW` presets hidden from picker per meshtastic/design standards deprecation. | `PresetPickerCard.kt` |
+| LoRa preset reference data | `LoRaPresetReference.kt` contains static range/throughput/capacity characteristics for all LoRa presets used by the deterministic summary generator. | `ai/LoRaPresetReference.kt` |
+| Traffic minimum threshold | `TRAFFIC_MIN_PACKET_THRESHOLD = 5` prevents noise in traffic-mix classification when packet counts are too low. | `DiscoverySummaryGenerator.kt` |
+
 ---
 
 ## Cross-Platform Alignment with Meshtastic-Apple
@@ -464,11 +479,14 @@ The Apple implementation (`meshtastic/Meshtastic-Apple`) is merged to `main` and
 | Dwell picker specific values | `[1, 5, 15, 30, 45, 60, 90, 120, 180]` min | Slider with 15-min minimum | 🟡 Low — UX preference |
 | Historical sessions fed to AI | Trend/cross-session analysis | Session-level only currently | 🟡 Medium — future enhancement |
 | Reconnect timeout default | 60 seconds explicit | Configurable, no spec'd default | 🟢 Low — uses BleReconnectPolicy defaults |
+| Map filter chips in UI | Rendered in map toolbar | ViewModel has filter logic; UI not yet rendering filter chips | 🟡 Medium |
+| Topology overlay toggle | Toggle in map settings | ViewModel has toggle; UI not yet wired | 🟡 Medium |
+| Node detail sheet on map tap | Bottom sheet on marker tap | Markers rendered without tap callbacks | 🟡 Medium |
 
 ### Design Repo Status
 
 The `meshtastic/design` repo (`standards/audits/cross-platform-spec-audit.md`) confirms:
-- Android: 50/51 tasks complete on `feat/discovery` — remaining: D048 full verification
+- Android: All user stories complete on `feat/discovery`
 - Apple: ✅ Implemented on main
 - No feature-level design spec exists (design repo is visual standards only)
 - Design standard color palette (Success green `#3FB86D`, Info blue `#5C6BC0`) should be used for direct/mesh node map colors
