feat(settings): LoTW 省份选择入口常驻 + 导入前预解析填充选项

- 省份入口从第一帧就在台站区：DXCC 未知时显示「导入证书后可选」占位，不可展开
- 选中 p12 后 400ms 防抖静默预解析（previewCertificate，只读不落库，密码副本用后清零），
  点「确认导入」之前下拉即可选省份；错密码/非 p12 静默保持占位，导入报错行为不变
- 修复导入成功不刷新 stationMeta：此前导入完成后省份下拉要关掉重开对话框才出现
- 无省份字段的国家（德国等）维持隐藏；后缀 seq 防慢预览覆盖新结果
- 新增 LoTWUploadRepositoryPreviewTest 2 例（TQSL 风格空密码夹具 test_tqsl_empty.p12，
  实测解析 DXCC 318、不落库、错密码映射 CERTIFICATE_PASSWORD）；en/zh 文案

core/data/src/main/java/com/rtbishop/look4sat/core/data/lotw/LoTWUploadRepository.kt

@@ -114,6 +114,19 @@ class LoTWUploadRepository internal constructor(
         }
     }
 
+    override suspend fun previewCertificate(data: ByteArray, password: CharArray): LoTWCertificate = withContext(Dispatchers.IO) {
+        mutex.withLock {
+            try {
+                if (data.isEmpty() || data.size > MAX_CERTIFICATE_BYTES) fail(LoTWProblem.CERTIFICATE_INVALID)
+                LoTWKeyMaterial.read(data, password, now()).info
+            } finally {
+                // Never keep the operator's password; the p12 bytes stay the caller's
+                // own copy (the dialog re-reads the file for every preview attempt).
+                password.fill('\u0000')
+            }
+        }
+    }
+
     override suspend fun saveCertificatePassword(password: CharArray): LoTWCertificate = withContext(Dispatchers.IO) {
         mutex.withLock {
             val stored = storage.read("certificate") ?: fail(LoTWProblem.CERTIFICATE_MISSING)

core/data/src/test/java/com/rtbishop/look4sat/core/data/lotw/LoTWUploadRepositoryPreviewTest.kt

@@ -0,0 +1,82 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * 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 com.rtbishop.look4sat.core.data.lotw
+
+import com.rtbishop.look4sat.core.domain.repository.LoTWOperationException
+import com.rtbishop.look4sat.core.domain.repository.LoTWProblem
+import kotlinx.coroutines.runBlocking
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertThrows
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * previewCertificate parses a .p12 without touching storage — just enough to
+ * learn the certificate's DXCC entity, so the settings dialog can offer the
+ * entity's Province/State dropdown before the operator confirms the import.
+ *
+ * Fixture test_tqsl_empty.p12 mirrors a modern TQSL export: PBES2/AES-256,
+ * empty password, TQSL subject attribute 1.3.6.1.4.1.12348.1.1 = BA7OPF and
+ * extensions .2/.3/.4 = first/last QSO date, DXCC 318 (China).
+ */
+class LoTWUploadRepositoryPreviewTest {
+
+    private class MemStorage : LoTWStorage {
+        val files = mutableMapOf<String, ByteArray>()
+        override fun read(name: String): ByteArray? = files[name]
+        override fun write(name: String, data: ByteArray) { files[name] = data.copyOf() }
+        override fun delete(name: String) { files.remove(name) }
+    }
+
+    private fun fixture(name: String): ByteArray =
+        javaClass.classLoader!!.getResourceAsStream(name)!!.use { it.readBytes() }
+
+    private fun repository(storage: MemStorage) = LoTWUploadRepository(
+        storage, { error("station config not needed") }, now = { System.currentTimeMillis() }
+    )
+
+    @Test
+    fun `preview parses TQSL-style certificate without persisting it`() {
+        runBlocking {
+            val storage = MemStorage()
+            val repo = repository(storage)
+            val info = repo.previewCertificate(fixture("test_tqsl_empty.p12"), charArrayOf())
+            assertEquals("BA7OPF", info.callsign)
+            assertEquals(318, info.dxcc)
+            assertEquals("2026-01-01", info.firstQsoDate)
+            assertTrue("nothing written", storage.files.isEmpty())
+            assertNull("no certificate stored", repo.certificate())
+        }
+    }
+
+    @Test
+    fun `wrong password fails as certificate password and wipes the attempt`() {
+        runBlocking {
+            val storage = MemStorage()
+            val repo = repository(storage)
+            val password = "definitely-wrong".toCharArray()
+            val error = assertThrows(LoTWOperationException::class.java) {
+                runBlocking { repo.previewCertificate(fixture("test_pbes2.p12"), password) }
+            }
+            assertEquals(LoTWProblem.CERTIFICATE_PASSWORD, error.reason)
+            assertTrue("password wiped", password.all { it == '\u0000' })
+            assertTrue("nothing written", storage.files.isEmpty())
+        }
+    }
+}

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/repository/ILoTWUploadRepository.kt

@@ -25,6 +25,9 @@ interface ILoTWUploadRepository {
     suspend fun certificate(): LoTWCertificate?
     suspend fun station(): LoTWStation?
     suspend fun importCertificate(data: ByteArray, password: CharArray): LoTWCertificate
+    /** Parse a .p12 without persisting it — enough to learn the certificate's DXCC
+     *  entity so the station form can offer its region field before the import. */
+    suspend fun previewCertificate(data: ByteArray, password: CharArray): LoTWCertificate
     suspend fun saveCertificatePassword(password: CharArray): LoTWCertificate
     suspend fun saveStation(station: LoTWStation): LoTWStation
     suspend fun removeCertificate()

core/presentation/src/main/res/values-zh/strings.xml

@@ -242,6 +242,8 @@
     <string name="prefs_lotw_upload_remove">移除证书</string>
     <string name="prefs_lotw_upload_station_title">台址</string>
     <string name="prefs_lotw_upload_region_hint">未选择</string>
+    <string name="prefs_lotw_upload_region_label">省份</string>
+    <string name="prefs_lotw_upload_region_pending">导入证书后可选</string>
     <string name="prefs_lotw_upload_grid">网格（逗号分隔，可多格）</string>
     <string name="prefs_lotw_upload_save">保存</string>
     <string name="prefs_lotw_upload_close">关闭</string>

core/presentation/src/main/res/values/strings.xml

@@ -271,6 +271,8 @@
     <string name="prefs_lotw_upload_remove">Remove certificate</string>
     <string name="prefs_lotw_upload_station_title">Station location</string>
     <string name="prefs_lotw_upload_region_hint">Not selected</string>
+    <string name="prefs_lotw_upload_region_label">Region</string>
+    <string name="prefs_lotw_upload_region_pending">Import certificate to select</string>
     <string name="prefs_lotw_upload_grid">Grid(s), comma-separated</string>
     <string name="prefs_lotw_upload_save">Save</string>
     <string name="prefs_lotw_upload_close">Close</string>

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/LoTWUploadConfigDialog.kt

@@ -59,6 +59,7 @@ import com.rtbishop.look4sat.core.presentation.CardButton
 import com.rtbishop.look4sat.core.presentation.LocalSpacing
 import com.rtbishop.look4sat.core.presentation.R
 import com.rtbishop.look4sat.core.presentation.SharedDialog
+import kotlinx.coroutines.delay
 
 @Composable
 fun LoTWUploadCard(
@@ -111,6 +112,7 @@ fun LoTWUploadConfigDialog(
     initialGrid: String = "",
     onDismiss: () -> Unit,
     onImport: (ByteArray, CharArray) -> Unit,
+    onPreview: (ByteArray, CharArray) -> Unit,
     onRemove: () -> Unit,
     onSaveStation: (LoTWStation) -> Unit
 ) {
@@ -155,6 +157,19 @@ fun LoTWUploadConfigDialog(
         }
     }.getOrNull() ?: uri.lastPathSegment.orEmpty()
 
+    // Surface the certificate's region field before the import is confirmed: re-read
+    // the picked .p12 whenever file or password changes (debounced) and hand it to a
+    // silent preview — a wrong password simply keeps the pending hint, a successful
+    // parse fills the Province/State dropdown in the station form below.
+    LaunchedEffect(selectedFile, password) {
+        val uri = selectedFile ?: return@LaunchedEffect
+        delay(400)
+        val bytes = runCatching {
+            context.contentResolver.openInputStream(uri)?.use { it.readBytes() }
+        }.getOrNull()
+        if (bytes != null && bytes.isNotEmpty()) onPreview(bytes, password.toCharArray())
+    }
+
     SharedDialog(
         title = stringResource(R.string.prefs_lotw_upload_title),
         onDismissRequest = onDismiss,
@@ -254,12 +269,15 @@ fun LoTWUploadConfigDialog(
             keyboardOptions = androidx.compose.foundation.text.KeyboardOptions(capitalization = KeyboardCapitalization.Characters),
             modifier = Modifier.fillMaxWidth()
         )
-        // Country-specific region field (US_STATE, CN_PROVINCE, …) shown only when
-        // the certificate's DXCC entity defines one; selecting it fills CQZ/ITUZ.
+        // Country-specific region field (US_STATE, CN_PROVINCE, …): the entry is part
+        // of the form from the first frame (pending hint while no DXCC is known), gets
+        // its options as soon as a certificate is previewed/imported, and a selection
+        // fills CQZ/ITUZ. Entities without a region field keep it hidden.
         // Drawn as a plain Box (not OutlinedTextField): a read-only text field's
         // internal gesture handler consumes the tap, so clickable never fires.
         // Options expand inline inside the sheet (no Popup/Dialog window stacking).
-        if (regionField != null) {
+        val regionPending = certificate == null && stationMeta == null
+        if (regionField != null || regionPending) {
             var regionExpanded by remember { mutableStateOf(false) }
             val fieldShape = MaterialTheme.shapes.extraSmall
             Box(
@@ -268,21 +286,25 @@ fun LoTWUploadConfigDialog(
                     .clip(fieldShape)
                     .background(MaterialTheme.colorScheme.surface)
                     .border(1.dp, MaterialTheme.colorScheme.outline, fieldShape)
-                    .clickable { regionExpanded = !regionExpanded }
+                    .clickable(enabled = regionField != null) { regionExpanded = !regionExpanded }
                     .padding(horizontal = 12.dp, vertical = 8.dp)
             ) {
                 Column {
-                    Text(regionField.label, fontSize = 12.sp, color = MaterialTheme.colorScheme.onSurfaceVariant)
+                    Text(
+                        text = regionField?.label ?: stringResource(R.string.prefs_lotw_upload_region_label),
+                        fontSize = 12.sp,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant
+                    )
                     Spacer(modifier = Modifier.height(3.dp))
                     Row(verticalAlignment = Alignment.CenterVertically) {
                         Text(
-                            text = if (region.isBlank()) {
-                                stringResource(R.string.prefs_lotw_upload_region_hint)
-                            } else {
-                                "$region — $selectedRegionName"
+                            text = when {
+                                regionPending -> stringResource(R.string.prefs_lotw_upload_region_pending)
+                                region.isBlank() -> stringResource(R.string.prefs_lotw_upload_region_hint)
+                                else -> "$region — $selectedRegionName"
                             },
                             fontSize = 16.sp,
-                            color = if (region.isBlank()) {
+                            color = if (regionPending || region.isBlank()) {
                                 MaterialTheme.colorScheme.onSurfaceVariant
                             } else {
                                 MaterialTheme.colorScheme.onSurface
@@ -299,9 +321,9 @@ fun LoTWUploadConfigDialog(
                     }
                 }
             }
-            AnimatedVisibility(visible = regionExpanded) {
+            AnimatedVisibility(visible = regionExpanded && regionField != null) {
                 LazyColumn(modifier = Modifier.fillMaxWidth().heightIn(max = 280.dp)) {
-                    items(regionField.options, key = { it.code }) { option ->
+                    items(regionField?.options.orEmpty(), key = { it.code }) { option ->
                         DropdownMenuItem(
                             text = { Text("${option.code} — ${option.name}", fontSize = 13.sp) },
                             onClick = {

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/LoTWUploadDestination.kt

@@ -64,6 +64,9 @@ fun LoTWUploadDestination(navigateUp: () -> Unit) {
             onImport = { bytes, password ->
                 viewModel.onAction(SettingsAction.ImportLoTWCertificate(bytes, password))
             },
+            onPreview = { bytes, password ->
+                viewModel.onAction(SettingsAction.PreviewLoTWCertificate(bytes, password))
+            },
             onRemove = { viewModel.onAction(SettingsAction.RemoveLoTWCertificate) },
             onSaveStation = { viewModel.onAction(SettingsAction.SaveLoTWStation(it)) }
         )

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsScreen.kt

@@ -343,6 +343,7 @@ private fun SettingsScreen(
                 onClearStationGridPrefill()
             },
             onImport = { bytes, password -> onAction(SettingsAction.ImportLoTWCertificate(bytes, password)) },
+            onPreview = { bytes, password -> onAction(SettingsAction.PreviewLoTWCertificate(bytes, password)) },
             onRemove = { onAction(SettingsAction.RemoveLoTWCertificate) },
             onSaveStation = { onAction(SettingsAction.SaveLoTWStation(it)) }
         )

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsState.kt

@@ -208,6 +208,8 @@ sealed interface SettingsAction {
     // LoTW upload configuration (certificate + station)
     data object LoadLoTWUploadStatus : SettingsAction
     data class ImportLoTWCertificate(val bytes: ByteArray, val password: CharArray) : SettingsAction
+    /** Pre-import .p12 parse (not persisted) so the region field appears before confirming. */
+    data class PreviewLoTWCertificate(val bytes: ByteArray, val password: CharArray) : SettingsAction
     data object RemoveLoTWCertificate : SettingsAction
     data class SaveLoTWStation(val station: com.rtbishop.look4sat.core.domain.repository.LoTWStation) : SettingsAction
 

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsViewModel.kt

@@ -267,6 +267,7 @@ class SettingsViewModel(
             // LoTW upload configuration
             SettingsAction.LoadLoTWUploadStatus -> loadLoTWUploadStatus()
             is SettingsAction.ImportLoTWCertificate -> importLoTWCertificate(action.bytes, action.password)
+            is SettingsAction.PreviewLoTWCertificate -> previewLoTWCertificate(action.bytes, action.password)
             SettingsAction.RemoveLoTWCertificate -> removeLoTWCertificate()
             is SettingsAction.SaveLoTWStation -> saveLoTWStation(action.station)
             // Update checker
@@ -788,7 +789,10 @@ class SettingsViewModel(
             _uiState.update { it.copy(lotwUploadBusy = true, lotwUploadError = null) }
             try {
                 val cert = lotwUploadRepository.importCertificate(bytes, password)
-                _uiState.update { it.copy(lotwCertificate = cert, lotwUploadBusy = false, lotwUploadError = null) }
+                // Publish the region field for the fresh certificate immediately —
+                // previously it only appeared after closing and reopening the dialog.
+                val meta = runCatching { lotwUploadRepository.stationMeta(cert.dxcc) }.getOrNull()
+                _uiState.update { it.copy(lotwCertificate = cert, lotwStationMeta = meta, lotwUploadBusy = false, lotwUploadError = null) }
             } catch (e: com.rtbishop.look4sat.core.domain.repository.LoTWOperationException) {
                 val error = when (e.reason) {
                     com.rtbishop.look4sat.core.domain.repository.LoTWProblem.CERTIFICATE_PASSWORD -> LoTWUploadError.PASSWORD
@@ -803,6 +807,24 @@ class SettingsViewModel(
         }
     }
 
+    // Monotonic token so a slow stale preview never overwrites a newer one's meta.
+    private var certificatePreviewSeq = 0
+
+    private fun previewLoTWCertificate(bytes: ByteArray, password: CharArray) {
+        val seq = ++certificatePreviewSeq
+        viewModelScope.launch {
+            // Silent by design: a wrong password or a non-p12 file must not disturb
+            // the dialog — only a successful parse publishes the region field.
+            val meta = runCatching { lotwUploadRepository.previewCertificate(bytes, password) }.fold(
+                onSuccess = { cert -> runCatching { lotwUploadRepository.stationMeta(cert.dxcc) }.getOrNull() },
+                onFailure = { null }
+            )
+            if (meta != null && seq == certificatePreviewSeq) {
+                _uiState.update { it.copy(lotwStationMeta = meta) }
+            }
+        }
+    }
+
     private fun removeLoTWCertificate() {
         viewModelScope.launch {
             lotwUploadRepository.removeCertificate()