diff --git a/.github/workflows/android.yml b/.github/workflows/android.yml
index 7c3f53f..b46ee22 100644
--- a/.github/workflows/android.yml
+++ b/.github/workflows/android.yml
@@ -63,7 +63,7 @@ jobs:
 
       - name: Android lint
         working-directory: android-app
-        run: gradle --no-daemon :app:lintDebug
+        run: gradle --no-daemon :app:lintDebug :app:lintRelease
 
       - name: Print complete lint failures
         if: failure()
@@ -130,6 +130,14 @@ jobs:
           if-no-files-found: error
           retention-days: 30
 
+      - name: Upload unsigned release candidate
+        uses: actions/upload-artifact@v4
+        with:
+          name: DH-Inspeccion-${{ steps.package.outputs.version }}-vc${{ steps.package.outputs.version_code }}-${{ steps.package.outputs.short_sha }}-UNSIGNED
+          path: android-app/app/build/outputs/apk/release/app-release-unsigned.apk
+          if-no-files-found: error
+          retention-days: 30
+
       - name: Upload Android diagnostics
         if: always()
         uses: actions/upload-artifact@v4
diff --git a/android-app/FINAL_RELEASE_CHECKLIST.md b/android-app/FINAL_RELEASE_CHECKLIST.md
index 7f21011..e94611a 100644
--- a/android-app/FINAL_RELEASE_CHECKLIST.md
+++ b/android-app/FINAL_RELEASE_CHECKLIST.md
@@ -1,4 +1,4 @@
-# Checklist final Android 0.19.0
+# Checklist final Android 0.19.1
 
 La candidata sólo se promueve si el mismo SHA cumple:
 
diff --git a/android-app/RELEASE.md b/android-app/RELEASE.md
index feef42a..0470ba1 100644
--- a/android-app/RELEASE.md
+++ b/android-app/RELEASE.md
@@ -1,10 +1,10 @@
-# DH Inspección Android · release final de campo 0.19.0
+# DH Inspección Android · release final de campo 0.19.1
 
 ## Candidata vigente
 
 - Fase funcional: **Flujo final de campo · Inspección → Acta → Hallazgos → Firma**.
-- `versionName`: **0.19.0**.
-- `versionCode`: **28**.
+- `versionName`: **0.19.1**.
+- `versionCode`: **29**.
 - Application ID release: `com.korexlabs.dhinspeccion`.
 - Application ID debug/QA: `com.korexlabs.dhinspeccion.debug`.
 - API: `https://dhv2.korexlabs.com/api/v3/`.
@@ -13,7 +13,7 @@ La variante debug es independiente de la app productiva y puede instalarse para
 
 ## Procedimiento operativo validado
 
-La APK 0.19.0 fija como recorrido principal de campo:
+La APK 0.19.1 fija como recorrido principal de campo:
 
 1. **Iniciar Inspección**. Al iniciarla se habilitan Actas, Hallazgos e Inventario de campo.
 2. **Crear o abrir un Acta**. Puede haber varias Actas dentro de una misma Inspección, pero sólo una puede permanecer en elaboración al mismo tiempo.
@@ -95,3 +95,16 @@ Antes de distribuir una APK productiva:
 - realizar actualización sobre al menos una tablet con la versión productiva anterior cuando corresponda;
 - ejecutar smoke funcional: ingreso, iniciar Inspección, crear Acta, seleccionar/crear Instalación o Subinstalación, GPS/foto, Hallazgo, cerrar Acta → Pendiente de firma, firma/manifestación, cierre de Acta y cierre de Inspección;
 - registrar el SHA Git y SHA-256 de la APK distribuida.
+
+## Revisión 0.19.1
+
+- Renovación de sesión coordinada entre los cuatro clientes API; no cierra sesión por pérdida de red, HTTP 429/500 o cancelación.
+- Una respuesta tardía no puede restaurar una sesión cerrada ni usar la de otro inspector.
+- Guardia de escrituras contra doble toque y conteo correcto de operaciones pendientes.
+- Búsquedas descartan respuestas antiguas. Cambio de inspección limpia el Acta anterior.
+- Mensajes visibles de permisos/GPS en evidencia y respeto de barras de sistema/teclado.
+- Diez nuevas pruebas de comportamiento sobre sesión y concurrencia.
+
+### Alcance real
+
+Esta candidata requiere conexión. No implementa trabajo offline ni cola persistente de sincronización; un fallo de red no equivale a guardado. Tras un timeout de escritura debe verificarse el registro antes de repetir. No se presenta el artefacto debug como una release productiva. La firma histórica y el smoke en tablet siguen siendo requisitos para distribuir la release final.
diff --git a/android-app/app/build.gradle.kts b/android-app/app/build.gradle.kts
index 7db8c79..9457ceb 100644
--- a/android-app/app/build.gradle.kts
+++ b/android-app/app/build.gradle.kts
@@ -12,8 +12,8 @@ android {
         applicationId = "com.korexlabs.dhinspeccion"
         minSdk = 26
         targetSdk = 36
-        versionCode = 28
-        versionName = "0.19.0"
+        versionCode = 29
+        versionName = "0.19.1"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true
diff --git a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/MainViewModel.kt b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/MainViewModel.kt
index 4d08601..0e18317 100644
--- a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/MainViewModel.kt
+++ b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/MainViewModel.kt
@@ -24,11 +24,14 @@ import com.korexlabs.dhinspeccion.data.MobileResponsibleRequest
 import com.korexlabs.dhinspeccion.data.StoredSession
 import com.korexlabs.dhinspeccion.data.VisitDetail
 import com.korexlabs.dhinspeccion.data.VisitSummary
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.launch
 import java.io.File
 import java.time.Instant
 
 class MainViewModel(application: Application) : AndroidViewModel(application) {
+    private val operations = OperationTracker()
+    private var inventorySearchGeneration = 0
     private val repository = DhRepository(application)
     private val findingsRepository = FieldFindingsRepository(application)
     private val actsRepository = MobileActsRepository(application)
@@ -84,7 +87,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
             error = "Ingresá usuario y contraseña."
             return
         }
-        launchBusy {
+        launchBusy(mutation = true) {
             session = repository.login(identifier, password)
             notice = "Sesión iniciada."
             loadVisitsInternal()
@@ -113,7 +116,9 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
     }
 
     fun openVisit(id: String) = launchBusy {
-        visit = repository.visit(id)
+        val loadedVisit = repository.visit(id)
+        clearActState()
+        visit = loadedVisit
         inventory = emptyList()
         inventoryParentId = visit?.scopeAsset?.id ?: visit?.operationalArea?.id
         fieldTypes = emptyList()
@@ -123,6 +128,8 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
     }
 
     fun closeVisitView() {
+        if (busy) return
+        inventorySearchGeneration += 1
         visit = null
         inventory = emptyList()
         inventoryParentId = null
@@ -135,7 +142,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
 
     fun startVisit() {
         val id = visit?.id ?: return
-        launchBusy {
+        launchBusy(mutation = true) {
             visit = repository.startVisit(id)
             inventoryParentId = visit?.scopeAsset?.id ?: visit?.operationalArea?.id
             notice = "Inspección iniciada."
@@ -172,7 +179,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
             error = "Ya existe un Acta en elaboración. Cerrala o cancelala antes de crear la siguiente."
             return
         }
-        launchBusy {
+        launchBusy(mutation = true) {
             val created = actsRepository.create(
                 currentVisit.id,
                 asset?.id,
@@ -194,8 +201,10 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
 
     fun searchInventory(search: String, parentId: String? = null) {
         val currentVisit = visit ?: return
+        val generation = ++inventorySearchGeneration
         launchBusy {
-            inventory = repository.fieldInventory(currentVisit.id, search, parentId).data
+            val result = repository.fieldInventory(currentVisit.id, search, parentId).data
+            if (generation == inventorySearchGeneration && visit?.id == currentVisit.id) inventory = result
         }
     }
 
@@ -203,6 +212,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
         val currentVisit = visit ?: return
         launchBusy {
             val effectiveParentId = parentId ?: currentVisit.scopeAsset?.id ?: currentVisit.operationalArea?.id
+            inventorySearchGeneration += 1
             inventoryParentId = effectiveParentId
             fieldTypes = repository.fieldTypes(currentVisit.id, parentId).data
             inventory = repository.fieldInventory(currentVisit.id, null, effectiveParentId).data
@@ -216,7 +226,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
 
     fun selectExisting(item: FieldInventoryItem) {
         val visitId = visit?.id ?: return
-        launchBusy {
+        launchBusy(mutation = true) {
             selectedFieldAsset = repository.selectFieldAsset(visitId, item.id)
             notice = "Inventario agregado a la Inspección."
             reloadCurrentInventory(visitId)
@@ -252,7 +262,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
             error = "Elegí una clasificación técnica o la opción Otro / no catalogado."
             return
         }
-        launchBusy {
+        launchBusy(mutation = true) {
             val request = CreateFieldInventoryRequest(
                 typeId = type.id,
                 parentId = parentId,
@@ -283,7 +293,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
             error = "Explicá brevemente por qué se trata de un duplicado."
             return
         }
-        launchBusy {
+        launchBusy(mutation = true) {
             val result = repository.mergeFieldAsset(
                 visitId = visitId,
                 assetId = source.id,
@@ -310,7 +320,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
     ) {
         val visitId = visit?.id ?: return
         val asset = selectedFieldAsset?.asset ?: return
-        launchBusy {
+        launchBusy(mutation = true) {
             val response = repository.uploadFieldPhoto(
                 visitId = visitId,
                 assetId = asset.id,
@@ -345,7 +355,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
             error = "Creá o seleccioná el Acta en elaboración antes de registrar Hallazgos."
             return
         }
-        launchBusy {
+        launchBusy(mutation = true) {
             selectedAct = actsRepository.ensureAsset(draft.id, assetId)
             loadActsInternal(visitId, selectDraft = false)
             loadFindingOptionsInternal(visitId, assetId, draft.id)
@@ -379,7 +389,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
             error = "La gravedad debe estar entre 1 y 10."
             return
         }
-        launchBusy {
+        launchBusy(mutation = true) {
             selectedAct = actsRepository.ensureAsset(actId, assetId)
             val response = findingsRepository.create(
                 visitId,
@@ -410,7 +420,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
         title: String? = null,
         description: String? = null,
     ) {
-        launchBusy {
+        launchBusy(mutation = true) {
             findingsRepository.uploadObservationPhoto(
                 findingId = findingId,
                 file = file,
@@ -442,7 +452,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
             error = "Completá nombre, documento y cargo del responsable de la empresa."
             return
         }
-        launchBusy {
+        launchBusy(mutation = true) {
             actClosure = actsRepository.setResponsible(
                 actId,
                 MobileResponsibleRequest(
@@ -465,7 +475,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
             error = "Indicá un motivo de ausencia de al menos 10 caracteres."
             return
         }
-        launchBusy {
+        launchBusy(mutation = true) {
             actClosure = actsRepository.setResponsible(
                 actId,
                 MobileResponsibleRequest(
@@ -479,7 +489,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
 
     fun prepareSelectedAct() {
         val actId = selectedAct?.id ?: return
-        launchBusy {
+        launchBusy(mutation = true) {
             actClosure = actsRepository.lock(actId)
             refreshSelectedActInternal(actId)
             notice = "Acta cerrada y pendiente de firma. Su contenido quedó inmutable; las firmas y manifestaciones pueden completarse a continuación."
@@ -497,7 +507,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
         accuracyM: Double?,
     ) {
         val actId = selectedAct?.id ?: return
-        launchBusy {
+        launchBusy(mutation = true) {
             actClosure = actsRepository.signInspector(actId, png, latitude, longitude, accuracyM)
             notice = "Firma del inspector incorporada al Acta."
         }
@@ -512,7 +522,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
         statement: String?,
     ) {
         val actId = selectedAct?.id ?: return
-        launchBusy {
+        launchBusy(mutation = true) {
             actClosure = actsRepository.signCompany(
                 actId, png, latitude, longitude, accuracyM, manifestation, statement,
             )
@@ -534,7 +544,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
             error = "Indicá un motivo de al menos 10 caracteres."
             return
         }
-        launchBusy {
+        launchBusy(mutation = true) {
             actClosure = actsRepository.companyOutcome(actId, status, reason)
             notice = "Negativa a firmar asentada."
         }
@@ -543,7 +553,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
     fun closeSelectedAct() {
         val currentVisit = visit ?: return
         val actId = selectedAct?.id ?: return
-        launchBusy {
+        launchBusy(mutation = true) {
             actClosure = actsRepository.seal(actId)
             refreshSelectedActInternal(actId)
             loadActsInternal(currentVisit.id, selectDraft = false)
@@ -554,7 +564,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
 
     fun closeInspection() {
         val visitId = visit?.id ?: return
-        launchBusy {
+        launchBusy(mutation = true) {
             visit = actsRepository.closeVisit(visitId)
             loadVisitsInternal()
             notice = "Inspección cerrada. Todas sus Actas quedaron firmadas y disponibles para el circuito de oficina."
@@ -637,17 +647,21 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
         fieldFindingEvidence = emptyMap()
     }
 
-    private fun launchBusy(block: suspend () -> Unit) {
+    private fun launchBusy(mutation: Boolean = false, block: suspend () -> Unit) {
+        if (!operations.begin(mutation)) return
+        busy = operations.busy
         viewModelScope.launch {
-            busy = true
             error = null
             try {
                 block()
+            } catch (cancelled: CancellationException) {
+                throw cancelled
             } catch (throwable: Throwable) {
                 error = DhRepository.humanError(throwable)
                 if (repository.currentSession() == null) session = null
             } finally {
-                busy = false
+                operations.end()
+                busy = operations.busy
             }
         }
     }
diff --git a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/OperationTracker.kt b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/OperationTracker.kt
new file mode 100644
index 0000000..7e47a6d
--- /dev/null
+++ b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/OperationTracker.kt
@@ -0,0 +1,16 @@
+package com.korexlabs.dhinspeccion
+
+/** Main-thread gate: reads may overlap; a second write is never queued by a double tap. */
+internal class OperationTracker {
+    private var pending = 0
+    val busy: Boolean get() = pending > 0
+    fun begin(mutation: Boolean): Boolean {
+        if (mutation && busy) return false
+        pending += 1
+        return true
+    }
+    fun end() {
+        check(pending > 0)
+        pending -= 1
+    }
+}
diff --git a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/DhMobile.kt b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/DhMobile.kt
index 72fe9cd..03861ee 100644
--- a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/DhMobile.kt
+++ b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/DhMobile.kt
@@ -7,8 +7,6 @@ import android.util.Base64
 import com.korexlabs.dhinspeccion.BuildConfig
 import com.squareup.moshi.Moshi
 import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
-import kotlinx.coroutines.sync.Mutex
-import kotlinx.coroutines.sync.withLock
 import okhttp3.MediaType.Companion.toMediaType
 import okhttp3.MultipartBody
 import okhttp3.OkHttpClient
@@ -451,7 +449,6 @@ class SecureSessionStore(context: Context) {
 
 class DhRepository(context: Context) {
     private val store = SecureSessionStore(context.applicationContext)
-    private val refreshMutex = Mutex()
     private val moshi = Moshi.Builder().addLast(KotlinJsonAdapterFactory()).build()
     private val api: DhApi = Retrofit.Builder()
         .baseUrl(BuildConfig.API_BASE_URL)
@@ -548,23 +545,19 @@ class DhRepository(context: Context) {
         } catch (error: HttpException) {
             if (error.code() != 401) throw error
         }
-        session = refresh(session.refreshToken)
+        session = refresh(session)
         return block(session)
     }
 
-    private suspend fun refresh(previousRefreshToken: String): StoredSession = refreshMutex.withLock {
-        val latest = store.load() ?: throw IllegalStateException("Sesión no iniciada")
-        if (latest.refreshToken != previousRefreshToken) return@withLock latest
-        try {
-            store.save(api.refresh(RefreshRequest(previousRefreshToken)))
-        } catch (error: Throwable) {
-            store.clear()
-            throw error
-        }
-    }
+    private suspend fun refresh(previous: StoredSession): StoredSession =
+        MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear, api::refresh)
+
 
     companion object {
         fun humanError(error: Throwable): String {
+            if (error is java.io.IOException) {
+                return "No se pudo conectar. Revisá la señal. Si estabas guardando, comprobá el registro antes de reintentar."
+            }
             if (error is HttpException) {
                 val body = runCatching { error.response()?.errorBody()?.string() }.getOrNull()
                 val message = runCatching { JSONObject(body.orEmpty()).optString("message") }.getOrNull()
diff --git a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/FieldFindingsMobile.kt b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/FieldFindingsMobile.kt
index 6690364..1c33037 100644
--- a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/FieldFindingsMobile.kt
+++ b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/FieldFindingsMobile.kt
@@ -4,8 +4,6 @@ import android.content.Context
 import com.korexlabs.dhinspeccion.BuildConfig
 import com.squareup.moshi.Moshi
 import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
-import kotlinx.coroutines.sync.Mutex
-import kotlinx.coroutines.sync.withLock
 import okhttp3.MediaType.Companion.toMediaType
 import okhttp3.MultipartBody
 import okhttp3.OkHttpClient
@@ -176,7 +174,6 @@ private interface FieldFindingsApi {
  */
 class FieldFindingsRepository(context: Context) {
     private val store = SecureSessionStore(context.applicationContext)
-    private val refreshMutex = Mutex()
     private val moshi = Moshi.Builder().addLast(KotlinJsonAdapterFactory()).build()
     private val api: FieldFindingsApi = Retrofit.Builder()
         .baseUrl(BuildConfig.API_BASE_URL)
@@ -241,18 +238,11 @@ class FieldFindingsRepository(context: Context) {
         } catch (error: HttpException) {
             if (error.code() != 401) throw error
         }
-        session = refresh(session.refreshToken)
+        session = refresh(session)
         return block(session)
     }
 
-    private suspend fun refresh(previousRefreshToken: String): StoredSession = refreshMutex.withLock {
-        val latest = store.load() ?: throw IllegalStateException("Sesión no iniciada")
-        if (latest.refreshToken != previousRefreshToken) return@withLock latest
-        try {
-            store.save(api.refresh(RefreshRequest(previousRefreshToken)))
-        } catch (error: Throwable) {
-            store.clear()
-            throw error
-        }
-    }
+    private suspend fun refresh(previous: StoredSession): StoredSession =
+        MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear, api::refresh)
+
 }
diff --git a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileActs.kt b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileActs.kt
index 68d6f85..e109716 100644
--- a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileActs.kt
+++ b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileActs.kt
@@ -4,8 +4,6 @@ import android.content.Context
 import com.korexlabs.dhinspeccion.BuildConfig
 import com.squareup.moshi.Moshi
 import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
-import kotlinx.coroutines.sync.Mutex
-import kotlinx.coroutines.sync.withLock
 import okhttp3.MediaType.Companion.toMediaType
 import okhttp3.MultipartBody
 import okhttp3.OkHttpClient
@@ -310,7 +308,6 @@ private interface MobileActsApi {
 
 class MobileActsRepository(context: Context) {
     private val store = SecureSessionStore(context.applicationContext)
-    private val refreshMutex = Mutex()
     private val moshi = Moshi.Builder().addLast(KotlinJsonAdapterFactory()).build()
     private val api: MobileActsApi = Retrofit.Builder()
         .baseUrl(BuildConfig.API_BASE_URL)
@@ -454,18 +451,11 @@ class MobileActsRepository(context: Context) {
         } catch (error: HttpException) {
             if (error.code() != 401) throw error
         }
-        session = refresh(session.refreshToken)
+        session = refresh(session)
         return block(session)
     }
 
-    private suspend fun refresh(previousRefreshToken: String): StoredSession = refreshMutex.withLock {
-        val latest = store.load() ?: throw IllegalStateException("Sesión no iniciada")
-        if (latest.refreshToken != previousRefreshToken) return@withLock latest
-        try {
-            store.save(api.refresh(RefreshRequest(previousRefreshToken)))
-        } catch (error: Throwable) {
-            store.clear()
-            throw error
-        }
-    }
+    private suspend fun refresh(previous: StoredSession): StoredSession =
+        MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear, api::refresh)
+
 }
diff --git a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileInspectionOpen.kt b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileInspectionOpen.kt
index c0a5e64..7b1e56e 100644
--- a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileInspectionOpen.kt
+++ b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileInspectionOpen.kt
@@ -4,8 +4,6 @@ import android.content.Context
 import com.korexlabs.dhinspeccion.BuildConfig
 import com.squareup.moshi.Moshi
 import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
-import kotlinx.coroutines.sync.Mutex
-import kotlinx.coroutines.sync.withLock
 import okhttp3.OkHttpClient
 import retrofit2.HttpException
 import retrofit2.Retrofit
@@ -55,7 +53,6 @@ private interface MobileInspectionOpenApi {
 
 class MobileInspectionOpenRepository(context: Context) {
     private val store = SecureSessionStore(context.applicationContext)
-    private val refreshMutex = Mutex()
     private val moshi = Moshi.Builder().addLast(KotlinJsonAdapterFactory()).build()
     private val api: MobileInspectionOpenApi = Retrofit.Builder()
         .baseUrl(BuildConfig.API_BASE_URL)
@@ -86,18 +83,11 @@ class MobileInspectionOpenRepository(context: Context) {
         } catch (error: HttpException) {
             if (error.code() != 401) throw error
         }
-        session = refresh(session.refreshToken)
+        session = refresh(session)
         return block(session)
     }
 
-    private suspend fun refresh(previousRefreshToken: String): StoredSession = refreshMutex.withLock {
-        val latest = store.load() ?: throw IllegalStateException("Sesión no iniciada")
-        if (latest.refreshToken != previousRefreshToken) return@withLock latest
-        try {
-            store.save(api.refresh(RefreshRequest(previousRefreshToken)))
-        } catch (error: Throwable) {
-            store.clear()
-            throw error
-        }
-    }
+    private suspend fun refresh(previous: StoredSession): StoredSession =
+        MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear, api::refresh)
+
 }
diff --git a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileSessionCoordinator.kt b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileSessionCoordinator.kt
new file mode 100644
index 0000000..5634267
--- /dev/null
+++ b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/data/MobileSessionCoordinator.kt
@@ -0,0 +1,32 @@
+package com.korexlabs.dhinspeccion.data
+
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+import retrofit2.HttpException
+
+/** One refresh lock for every API client sharing the encrypted session. */
+internal object MobileSessionCoordinator {
+    private val mutex = Mutex()
+
+    suspend fun refresh(
+        previous: StoredSession,
+        load: () -> StoredSession?,
+        save: (MobileSessionResponse) -> StoredSession,
+        clear: () -> Unit,
+        request: suspend (RefreshRequest) -> MobileSessionResponse,
+    ): StoredSession = mutex.withLock {
+        val latest = load() ?: throw IllegalStateException("Sesión no iniciada")
+        check(latest.userId == previous.userId) { "La sesión cambió. Volvé a abrir la operación." }
+        if (latest.refreshToken != previous.refreshToken) return@withLock latest
+        val response = try {
+            request(RefreshRequest(previous.refreshToken))
+        } catch (error: HttpException) {
+            // Network failures and server outages must not discard the saved login.
+            if (error.code() == 401 && load()?.refreshToken == previous.refreshToken) clear()
+            throw error
+        }
+        // A logout or another login during the request must never be undone.
+        check(load()?.refreshToken == previous.refreshToken) { "La sesión cambió. Volvé a ingresar." }
+        save(response)
+    }
+}
diff --git a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/ui/FieldFindingScreen.kt b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/ui/FieldFindingScreen.kt
index a0cf697..c002404 100644
--- a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/ui/FieldFindingScreen.kt
+++ b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/ui/FieldFindingScreen.kt
@@ -75,6 +75,7 @@ fun FieldFindingScreen(model: MainViewModel) {
     var severityText by rememberSaveable(asset.id) { mutableStateOf("") }
     var correctionDueOn by rememberSaveable(asset.id) { mutableStateOf("") }
 
+    var localError by rememberSaveable { mutableStateOf<String?>(null) }
     var requestedFindingId by remember { mutableStateOf<String?>(null) }
     var pendingPhotoFile by remember { mutableStateOf<File?>(null) }
     var pendingPhotoGeo by remember { mutableStateOf<FindingGeoSnapshot?>(null) }
@@ -110,6 +111,7 @@ fun FieldFindingScreen(model: MainViewModel) {
                     pendingPhotoFindingId = findingId
                     takePicture.launch(uri)
                 }
+                .onFailure { localError = it.message ?: "No se pudo capturar la ubicación GPS." }
         }
     }
 
@@ -122,6 +124,7 @@ fun FieldFindingScreen(model: MainViewModel) {
         val findingId = requestedFindingId
         requestedFindingId = null
         if (camera && location && findingId != null) beginPhoto(findingId)
+        else localError = "Permití cámara y ubicación para adjuntar una foto con GPS."
     }
 
     fun requestPhoto(findingId: String) {
@@ -192,6 +195,7 @@ fun FieldFindingScreen(model: MainViewModel) {
             }
         }
 
+        localError?.let { Text(it, color = MaterialTheme.colorScheme.error) }
         model.error?.let {
             Card(colors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.errorContainer)) {
                 Text(it, Modifier.padding(12.dp))
diff --git a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/ui/LoginGate.kt b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/ui/LoginGate.kt
index 96b8090..4a7c980 100644
--- a/android-app/app/src/main/java/com/korexlabs/dhinspeccion/ui/LoginGate.kt
+++ b/android-app/app/src/main/java/com/korexlabs/dhinspeccion/ui/LoginGate.kt
@@ -11,6 +11,10 @@ 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.layout.safeDrawingPadding
+import androidx.compose.foundation.layout.imePadding
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Visibility
 import androidx.compose.material.icons.filled.VisibilityOff
@@ -80,7 +84,7 @@ fun DhRoot(model: MainViewModel, activity: FragmentActivity) {
     }
 
     DhTheme {
-        Surface(Modifier.fillMaxSize()) {
+        Surface(Modifier.fillMaxSize().safeDrawingPadding().imePadding()) {
             when {
                 model.session == null -> EnhancedLoginScreen(model) {
                     passwordLoginInFlight = true
@@ -106,10 +110,10 @@ fun DhRoot(model: MainViewModel, activity: FragmentActivity) {
 @Composable
 private fun EnhancedLoginScreen(model: MainViewModel, onPasswordLogin: () -> Unit) {
     var identifier by rememberSaveable { mutableStateOf("") }
-    var password by rememberSaveable { mutableStateOf("") }
+    var password by remember { mutableStateOf("") }
     var passwordVisible by rememberSaveable { mutableStateOf(false) }
 
-    Box(Modifier.fillMaxSize().padding(24.dp), contentAlignment = Alignment.Center) {
+    Box(Modifier.fillMaxSize().verticalScroll(rememberScrollState()).padding(24.dp), contentAlignment = Alignment.Center) {
         Column(Modifier.fillMaxWidth(), verticalArrangement = Arrangement.spacedBy(14.dp), horizontalAlignment = Alignment.CenterHorizontally) {
             Image(
                 painter = painterResource(R.drawable.ic_mendoza_launcher_exact),
@@ -203,7 +207,7 @@ private fun BiometricUnlockScreen(
 
     LaunchedEffect(Unit) { authenticate() }
 
-    Box(Modifier.fillMaxSize().padding(24.dp), contentAlignment = Alignment.Center) {
+    Box(Modifier.fillMaxSize().verticalScroll(rememberScrollState()).padding(24.dp), contentAlignment = Alignment.Center) {
         Column(
             Modifier.fillMaxWidth(),
             verticalArrangement = Arrangement.spacedBy(14.dp),
diff --git a/android-app/app/src/test/java/com/korexlabs/dhinspeccion/MobileSessionCoordinatorTest.kt b/android-app/app/src/test/java/com/korexlabs/dhinspeccion/MobileSessionCoordinatorTest.kt
new file mode 100644
index 0000000..5e3b16b
--- /dev/null
+++ b/android-app/app/src/test/java/com/korexlabs/dhinspeccion/MobileSessionCoordinatorTest.kt
@@ -0,0 +1,105 @@
+package com.korexlabs.dhinspeccion
+
+import com.korexlabs.dhinspeccion.data.*
+import java.io.IOException
+import kotlinx.coroutines.*
+import okhttp3.ResponseBody.Companion.toResponseBody
+import org.junit.Assert.*
+import org.junit.Test
+import retrofit2.HttpException
+import retrofit2.Response
+
+class MobileSessionCoordinatorTest {
+    private fun old() = StoredSession("u1", "inspector", "Inspector", "a1", "r1")
+    private fun response() = MobileSessionResponse(MobileUser("u1", "inspector"), "a2", "r2", 900)
+    private fun http(code: Int) = HttpException(Response.error<Unit>(code, "error".toResponseBody()))
+
+    private class Store(var value: StoredSession?) {
+        var clears = 0
+        fun load() = value
+        fun clear() { clears++; value = null }
+        fun save(r: MobileSessionResponse): StoredSession =
+            StoredSession(r.user.id, r.user.username, r.user.username, r.accessToken, r.refreshToken).also { value = it }
+    }
+
+    @Test fun concurrentClientsRotateTheTokenOnlyOnce() = runBlocking {
+        val previous = old(); val store = Store(previous); var calls = 0
+        val results = coroutineScope {
+            (1..4).map {
+                async {
+                    MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear) {
+                        calls++; delay(20); response()
+                    }
+                }
+            }.awaitAll()
+        }
+        assertEquals(1, calls)
+        assertTrue(results.all { it.refreshToken == "r2" })
+        assertEquals(0, store.clears)
+    }
+
+    @Test fun networkAndServerFailuresKeepSessionForRetry() = runBlocking {
+        for (failure in listOf(IOException("offline"), http(500), http(429))) {
+            val previous = old(); val store = Store(previous)
+            try {
+                MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear) { throw failure }
+                fail("Expected request failure")
+            } catch (caught: Exception) { assertSame(failure, caught) }
+            assertEquals(previous, store.value)
+            assertEquals(0, store.clears)
+        }
+    }
+
+    @Test fun invalidRefreshClearsOnlyTheExpiredSession() = runBlocking {
+        val previous = old(); val store = Store(previous)
+        try {
+            MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear) { throw http(401) }
+            fail("Expected unauthorized")
+        } catch (caught: HttpException) { assertEquals(401, caught.code()) }
+        assertNull(store.value)
+        assertEquals(1, store.clears)
+    }
+
+    @Test fun cancelledRefreshKeepsSession() = runBlocking {
+        val previous = old(); val store = Store(previous)
+        try {
+            MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear) { throw CancellationException("cancel") }
+            fail("Expected cancellation")
+        } catch (_: CancellationException) { }
+        assertEquals(previous, store.value)
+    }
+
+    @Test fun logoutDuringRefreshCannotBeUndone() = runBlocking {
+        val previous = old(); val store = Store(previous)
+        try {
+            MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear) {
+                store.clear(); response()
+            }
+            fail("Must reject a refresh after logout")
+        } catch (_: IllegalStateException) { }
+        assertNull(store.value)
+    }
+
+    @Test fun staleRequestCannotUseAnotherInspectorsSession() = runBlocking {
+        val previous = old(); val store = Store(previous.copy(userId = "u2", refreshToken = "other"))
+        try {
+            MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear) {
+                fail("No refresh allowed for another inspector"); response()
+            }
+            fail("Must reject account switch")
+        } catch (_: IllegalStateException) { }
+        assertEquals("u2", store.value?.userId)
+    }
+
+    @Test fun lateUnauthorizedDoesNotClearANewLogin() = runBlocking {
+        val previous = old(); val store = Store(previous)
+        try {
+            MobileSessionCoordinator.refresh(previous, store::load, store::save, store::clear) {
+                store.value = previous.copy(refreshToken = "new-login")
+                throw http(401)
+            }
+        } catch (_: HttpException) { }
+        assertEquals("new-login", store.value?.refreshToken)
+        assertEquals(0, store.clears)
+    }
+}
diff --git a/android-app/app/src/test/java/com/korexlabs/dhinspeccion/OperationTrackerTest.kt b/android-app/app/src/test/java/com/korexlabs/dhinspeccion/OperationTrackerTest.kt
new file mode 100644
index 0000000..2543f2b
--- /dev/null
+++ b/android-app/app/src/test/java/com/korexlabs/dhinspeccion/OperationTrackerTest.kt
@@ -0,0 +1,28 @@
+package com.korexlabs.dhinspeccion
+
+import org.junit.Assert.*
+import org.junit.Test
+
+class OperationTrackerTest {
+    @Test fun doubleTapCannotQueueASecondWrite() {
+        val tracker = OperationTracker()
+        assertTrue(tracker.begin(mutation = true))
+        assertFalse(tracker.begin(mutation = true))
+        tracker.end()
+        assertFalse(tracker.busy)
+        assertTrue(tracker.begin(mutation = true))
+    }
+    @Test fun BusyRemainsUntilEveryReadCompletes() {
+        val tracker = OperationTracker()
+        assertTrue(tracker.begin(false)); assertTrue(tracker.begin(false))
+        tracker.end(); assertTrue(tracker.busy)
+        assertFalse(tracker.begin(true))
+        tracker.end(); assertFalse(tracker.busy)
+    }
+    @Test fun readDuringWriteDoesNotReleaseItsGuardEarly() {
+        val tracker = OperationTracker()
+        assertTrue(tracker.begin(true)); assertTrue(tracker.begin(false))
+        tracker.end(); assertFalse(tracker.begin(true))
+        tracker.end(); assertTrue(tracker.begin(true))
+    }
+}
diff --git a/android-app/app/src/test/java/com/korexlabs/dhinspeccion/ReleaseMetadataTest.kt b/android-app/app/src/test/java/com/korexlabs/dhinspeccion/ReleaseMetadataTest.kt
index 9ee72cf..ccb74d4 100644
--- a/android-app/app/src/test/java/com/korexlabs/dhinspeccion/ReleaseMetadataTest.kt
+++ b/android-app/app/src/test/java/com/korexlabs/dhinspeccion/ReleaseMetadataTest.kt
@@ -8,8 +8,8 @@ class ReleaseMetadataTest {
     @Test
     fun debugBuildKeepsSeparateApplicationIdentity() {
         assertEquals("com.korexlabs.dhinspeccion.debug", BuildConfig.APPLICATION_ID)
-        assertEquals(28, BuildConfig.VERSION_CODE)
-        assertEquals("0.19.0-debug", BuildConfig.VERSION_NAME)
+        assertEquals(29, BuildConfig.VERSION_CODE)
+        assertEquals("0.19.1-debug", BuildConfig.VERSION_NAME)
     }
 
     @Test