diff --git a/backend/build.gradle.kts b/backend/build.gradle.kts
index 3fc3a47e..d4e7a9b3 100644
--- a/backend/build.gradle.kts
+++ b/backend/build.gradle.kts
@@ -66,6 +66,9 @@ extra["commons-lang3.version"] = "3.18.0"
 // logback-core 1.5.34 -> 1.5.35 fixes CVE (object injection via HardenedObjectInputStream, Dependabot #79).
 // Spring Boot 3.5.16 BOM pins 1.5.34; override the shared property so logback-core AND logback-classic move together.
 extra["logback.version"] = "1.5.35"
+// postgresql 42.7.11 -> 42.7.12 fixes CVE-2026-54291 (HIGH). Spring Boot 3.5.16 BOM pins 42.7.11;
+// override the managed property so the runtime JDBC driver picks up the patched release.
+extra["postgresql.version"] = "42.7.12"
 
 // Override Spring Boot BOM version for Testcontainers to support Docker Desktop 4.x on Windows
 dependencyManagement {
diff --git a/backend/gradle.lockfile b/backend/gradle.lockfile
index 42f0cf5b..aa7f49e2 100644
--- a/backend/gradle.lockfile
+++ b/backend/gradle.lockfile
@@ -141,7 +141,7 @@ org.mockito:mockito-junit-jupiter:5.17.0=testCompileClasspath,testRuntimeClasspa
 org.objenesis:objenesis:3.4=testCompileClasspath,testRuntimeClasspath
 org.opentest4j:opentest4j:1.3.0=testCompileClasspath,testRuntimeClasspath
 org.ow2.asm:asm:9.7.1=compileClasspath,productionRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
-org.postgresql:postgresql:42.7.11=productionRuntimeClasspath,runtimeClasspath,testRuntimeClasspath
+org.postgresql:postgresql:42.7.12=productionRuntimeClasspath,runtimeClasspath,testRuntimeClasspath
 org.reactivestreams:reactive-streams:1.0.4=compileClasspath,productionRuntimeClasspath,runtimeClasspath,testCompileClasspath,testRuntimeClasspath
 org.rnorth.duct-tape:duct-tape:1.0.8=testCompileClasspath,testRuntimeClasspath
 org.skyscreamer:jsonassert:1.5.3=testCompileClasspath,testRuntimeClasspath
diff --git a/backend/src/main/kotlin/com/taskowolf/automation/application/ActionExecutor.kt b/backend/src/main/kotlin/com/taskowolf/automation/application/ActionExecutor.kt
index 539fc134..16e91e4d 100644
--- a/backend/src/main/kotlin/com/taskowolf/automation/application/ActionExecutor.kt
+++ b/backend/src/main/kotlin/com/taskowolf/automation/application/ActionExecutor.kt
@@ -55,9 +55,10 @@ class ActionExecutor(
                     notificationService.createDirect(
                         userId = recipientId,
                         type = NotificationType.AUTOMATION,
-                        title = "Automation: ${issue.key}",
-                        body = message,
-                        link = "/p/${issue.project.key}/issues/${issue.key}"
+                        titleKey = "notification.automation.title",
+                        link = "/p/${issue.project.key}/issues/${issue.key}",
+                        titleArgs = arrayOf(issue.key),
+                        rawBody = message,
                     )
                 }
                 ActionType.CREATE_COMMENT -> {
diff --git a/backend/src/main/kotlin/com/taskowolf/notifications/application/EmailService.kt b/backend/src/main/kotlin/com/taskowolf/notifications/application/EmailService.kt
index fb0ebfe7..681b3d1c 100644
--- a/backend/src/main/kotlin/com/taskowolf/notifications/application/EmailService.kt
+++ b/backend/src/main/kotlin/com/taskowolf/notifications/application/EmailService.kt
@@ -1,6 +1,7 @@
 package com.taskowolf.notifications.application
 
 import com.taskowolf.comments.domain.events.MentionEvent
+import com.taskowolf.core.infrastructure.LocalizedMessages
 import com.taskowolf.issues.domain.events.IssueFieldChangedEvent
 import com.taskowolf.notifications.domain.NotificationChannel
 import com.taskowolf.notifications.domain.NotificationType
@@ -15,7 +16,8 @@ class EmailService(
     private val preferences: NotificationPreferenceService,
     private val mailSender: JavaMailSender,
     @Value("\${spring.mail.host:}") private val mailHost: String,
-    @Value("\${taskowolf.smtp.from:TaskWolf <noreply@example.com>}") private val fromAddress: String
+    @Value("\${taskowolf.smtp.from:TaskWolf <noreply@example.com>}") private val fromAddress: String,
+    private val localizedMessages: LocalizedMessages
 ) {
     private val enabled get() = mailHost.isNotBlank()
 
@@ -23,15 +25,15 @@ class EmailService(
     fun onMention(event: MentionEvent) {
         if (!enabled) return
         if (!preferences.isEnabled(event.mentionedUser.id, NotificationType.COMMENT_MENTION, NotificationChannel.EMAIL)) return
+        val locale = localizedMessages.localeOf(event.mentionedUser)
         val msg = SimpleMailMessage().apply {
             from = fromAddress
             setTo(event.mentionedUser.email)
-            subject = "You were mentioned in ${event.issue.key}"
-            text = """
-                |${event.issue.key}: ${event.issue.title}
-                |
-                |${event.comment.body.take(500)}
-            """.trimMargin()
+            subject = localizedMessages.get("email.mention.subject", locale, event.issue.key)
+            text = localizedMessages.get(
+                "email.mention.body", locale,
+                event.issue.key, event.issue.title, event.comment.body.take(500)
+            )
         }
         mailSender.send(msg)
     }
@@ -41,14 +43,12 @@ class EmailService(
         if (!enabled || event.field != "assignee") return
         val assignee = event.issue.assignee ?: return
         if (!preferences.isEnabled(assignee.id, NotificationType.ISSUE_ASSIGNED, NotificationChannel.EMAIL)) return
+        val locale = localizedMessages.localeOf(assignee)
         val msg = SimpleMailMessage().apply {
             from = fromAddress
             setTo(assignee.email)
-            subject = "You were assigned to ${event.issue.key}"
-            text = """
-                |You have been assigned to: ${event.issue.key}
-                |${event.issue.title}
-            """.trimMargin()
+            subject = localizedMessages.get("email.assigned.subject", locale, event.issue.key)
+            text = localizedMessages.get("email.assigned.body", locale, event.issue.key, event.issue.title)
         }
         mailSender.send(msg)
     }
diff --git a/backend/src/main/kotlin/com/taskowolf/notifications/application/NotificationService.kt b/backend/src/main/kotlin/com/taskowolf/notifications/application/NotificationService.kt
index 53a3ecfc..b278280a 100644
--- a/backend/src/main/kotlin/com/taskowolf/notifications/application/NotificationService.kt
+++ b/backend/src/main/kotlin/com/taskowolf/notifications/application/NotificationService.kt
@@ -1,6 +1,8 @@
 package com.taskowolf.notifications.application
 
+import com.taskowolf.auth.infrastructure.UserRepository
 import com.taskowolf.comments.domain.events.MentionEvent
+import com.taskowolf.core.infrastructure.LocalizedMessages
 import com.taskowolf.core.infrastructure.NotFoundException
 import com.taskowolf.issues.domain.events.IssueFieldChangedEvent
 import com.taskowolf.notifications.domain.Notification
@@ -12,23 +14,27 @@ import org.springframework.data.domain.Page
 import org.springframework.data.domain.PageRequest
 import org.springframework.stereotype.Service
 import org.springframework.transaction.annotation.Transactional
+import java.util.Locale
 import java.util.UUID
 
 @Service
 class NotificationService(
     private val repository: NotificationRepository,
-    private val preferences: NotificationPreferenceService
+    private val preferences: NotificationPreferenceService,
+    private val localizedMessages: LocalizedMessages,
+    private val userRepository: UserRepository
 ) {
 
     @EventListener
     @Transactional
     fun onMention(event: MentionEvent) {
         if (!preferences.isEnabled(event.mentionedUser.id, NotificationType.COMMENT_MENTION, NotificationChannel.IN_APP)) return
+        val locale = localizedMessages.localeOf(event.mentionedUser)
         repository.save(
             Notification(
                 userId = event.mentionedUser.id,
                 type = NotificationType.COMMENT_MENTION,
-                title = "You were mentioned in ${event.issue.key}",
+                title = localizedMessages.get("notification.mention.title", locale, event.issue.key),
                 body = event.comment.body.take(200),
                 link = "/issues/${event.issue.key}"
             )
@@ -41,11 +47,12 @@ class NotificationService(
         if (event.field != "assignee") return
         val assignee = event.issue.assignee ?: return
         if (!preferences.isEnabled(assignee.id, NotificationType.ISSUE_ASSIGNED, NotificationChannel.IN_APP)) return
+        val locale = localizedMessages.localeOf(assignee)
         repository.save(
             Notification(
                 userId = assignee.id,
                 type = NotificationType.ISSUE_ASSIGNED,
-                title = "You were assigned to ${event.issue.key}",
+                title = localizedMessages.get("notification.assigned.title", locale, event.issue.key),
                 body = event.issue.title,
                 link = "/issues/${event.issue.key}"
             )
@@ -70,9 +77,27 @@ class NotificationService(
     @Transactional(readOnly = true)
     fun countUnread(userId: UUID): Long = repository.countByUserIdAndReadFalse(userId)
 
+    /**
+     * Creates a notification, rendering [titleKey] (and optional [bodyKey]) in the recipient's
+     * stored language. Pass [rawBody] for a user-content body that must not be translated; if
+     * neither [bodyKey] nor [rawBody] is set, the body is empty.
+     */
     @Transactional
-    fun createDirect(userId: UUID, type: NotificationType, title: String, body: String, link: String) {
+    fun createDirect(
+        userId: UUID,
+        type: NotificationType,
+        titleKey: String,
+        link: String,
+        titleArgs: Array<out Any?> = emptyArray(),
+        bodyKey: String? = null,
+        bodyArgs: Array<out Any?> = emptyArray(),
+        rawBody: String? = null,
+    ) {
         if (!preferences.isEnabled(userId, type, NotificationChannel.IN_APP)) return
+        val locale = userRepository.findById(userId)
+            .map(localizedMessages::localeOf).orElse(Locale.ENGLISH)
+        val title = localizedMessages.get(titleKey, locale, *titleArgs)
+        val body = if (bodyKey != null) localizedMessages.get(bodyKey, locale, *bodyArgs) else rawBody.orEmpty()
         repository.save(Notification(userId = userId, type = type, title = title, body = body, link = link))
     }
 }
diff --git a/backend/src/main/kotlin/com/taskowolf/servicedesk/application/IncidentService.kt b/backend/src/main/kotlin/com/taskowolf/servicedesk/application/IncidentService.kt
index acbd624d..cb303ac1 100644
--- a/backend/src/main/kotlin/com/taskowolf/servicedesk/application/IncidentService.kt
+++ b/backend/src/main/kotlin/com/taskowolf/servicedesk/application/IncidentService.kt
@@ -2,6 +2,7 @@ package com.taskowolf.servicedesk.application
 
 import com.taskowolf.comments.domain.Comment
 import com.taskowolf.comments.infrastructure.CommentRepository
+import com.taskowolf.issues.infrastructure.IssueRepository
 import com.taskowolf.notifications.application.NotificationService
 import com.taskowolf.notifications.domain.NotificationType
 import com.taskowolf.servicedesk.domain.Incident
@@ -16,7 +17,8 @@ import java.util.UUID
 class IncidentService(
     private val incidentRepo: IncidentRepository,
     private val commentRepo: CommentRepository,
-    private val notificationService: NotificationService
+    private val notificationService: NotificationService,
+    private val issueRepository: IssueRepository
 ) {
     companion object {
         /** Null authorId used for system-generated comments (no FK violation since author_id is nullable). */
@@ -26,14 +28,19 @@ class IncidentService(
     @Transactional
     fun create(issueId: UUID, severity: IncidentSeverity, onCallAssigneeId: UUID?, notifyUserIds: List<UUID>): Incident {
         val incident = incidentRepo.save(Incident(issueId = issueId, severity = severity, onCallAssigneeId = onCallAssigneeId))
-        notifyUserIds.forEach { uid ->
-            notificationService.createDirect(
-                userId = uid,
-                type = NotificationType.AUTOMATION,
-                title = "Incident declared: ${severity.name} on issue $issueId",
-                body = "A ${severity.name} incident has been declared for issue $issueId.",
-                link = "/issues/$issueId"
-            )
+        if (notifyUserIds.isNotEmpty()) {
+            val issueKey = issueRepository.findById(issueId).map { it.key }.orElse(issueId.toString())
+            notifyUserIds.forEach { uid ->
+                notificationService.createDirect(
+                    userId = uid,
+                    type = NotificationType.AUTOMATION,
+                    titleKey = "notification.incident.title",
+                    link = "/issues/$issueKey",
+                    titleArgs = arrayOf(severity.name, issueKey),
+                    bodyKey = "notification.incident.body",
+                    bodyArgs = arrayOf(severity.name, issueKey),
+                )
+            }
         }
         return incident
     }
diff --git a/backend/src/main/kotlin/com/taskowolf/servicedesk/application/SlaMonitorJob.kt b/backend/src/main/kotlin/com/taskowolf/servicedesk/application/SlaMonitorJob.kt
index 36c0f19e..f06f7cf1 100644
--- a/backend/src/main/kotlin/com/taskowolf/servicedesk/application/SlaMonitorJob.kt
+++ b/backend/src/main/kotlin/com/taskowolf/servicedesk/application/SlaMonitorJob.kt
@@ -50,9 +50,11 @@ class SlaMonitorJob(
                         notificationService.createDirect(
                             userId = uid,
                             type = NotificationType.SLA_BREACHED,
-                            title = "SLA Breached: ${issue.key}",
-                            body = "Issue ${issue.key} has exceeded its SLA resolution time of ${policy.resolutionMinutes} minutes.",
-                            link = "/issues/${issue.key}"
+                            titleKey = "notification.slaBreached.title",
+                            link = "/issues/${issue.key}",
+                            titleArgs = arrayOf(issue.key),
+                            bodyKey = "notification.slaBreached.body",
+                            bodyArgs = arrayOf(issue.key, policy.resolutionMinutes.toString()),
                         )
                     }
                 }
diff --git a/backend/src/main/resources/messages.properties b/backend/src/main/resources/messages.properties
index e518a395..c8d6b7f4 100644
--- a/backend/src/main/resources/messages.properties
+++ b/backend/src/main/resources/messages.properties
@@ -140,3 +140,17 @@ serviceDesk.notEnabled=Service desk not enabled for project: {0}
 serviceDesk.invalidPriority=Invalid priority: {0}. Valid values: {1}
 # --- incident ---
 incident.invalidSeverity=Invalid severity ''{0}''. Must be one of: {1}
+
+# --- email ---
+email.mention.subject=You were mentioned in {0}
+email.mention.body={0}: {1}\n\n{2}
+email.assigned.subject=You were assigned to {0}
+email.assigned.body=You have been assigned to: {0}\n{1}
+# --- notification titles + templated bodies ---
+notification.mention.title=You were mentioned in {0}
+notification.assigned.title=You were assigned to {0}
+notification.incident.title=Incident declared: {0} on issue {1}
+notification.incident.body=A {0} incident has been declared for issue {1}.
+notification.slaBreached.title=SLA Breached: {0}
+notification.slaBreached.body=Issue {0} has exceeded its SLA resolution time of {1} minutes.
+notification.automation.title=Automation: {0}
diff --git a/backend/src/main/resources/messages_de.properties b/backend/src/main/resources/messages_de.properties
index 9b6b1c76..62f5b060 100644
--- a/backend/src/main/resources/messages_de.properties
+++ b/backend/src/main/resources/messages_de.properties
@@ -140,3 +140,17 @@ serviceDesk.notEnabled=Servicedesk ist f\u00fcr Projekt {0} nicht aktiviert
 serviceDesk.invalidPriority=Ung\u00fcltige Priorit\u00e4t: {0}. G\u00fcltige Werte: {1}
 # --- incident ---
 incident.invalidSeverity=Ung\u00fcltiger Schweregrad ''{0}''. Muss einer von: {1}
+
+# --- email ---
+email.mention.subject=Sie wurden in {0} erw\u00e4hnt
+email.mention.body={0}: {1}\n\n{2}
+email.assigned.subject=Ihnen wurde {0} zugewiesen
+email.assigned.body=Sie wurden zugewiesen zu: {0}\n{1}
+# --- notification titles + templated bodies ---
+notification.mention.title=Sie wurden in {0} erw\u00e4hnt
+notification.assigned.title=Ihnen wurde {0} zugewiesen
+notification.incident.title=Incident gemeldet: {0} f\u00fcr Vorgang {1}
+notification.incident.body=Ein {0}-Incident wurde f\u00fcr Vorgang {1} gemeldet.
+notification.slaBreached.title=SLA verletzt: {0}
+notification.slaBreached.body=Vorgang {0} hat seine SLA-L\u00f6sungszeit von {1} Minuten \u00fcberschritten.
+notification.automation.title=Automatisierung: {0}
diff --git a/backend/src/test/kotlin/com/taskowolf/automation/ActionExecutorTest.kt b/backend/src/test/kotlin/com/taskowolf/automation/ActionExecutorTest.kt
index bb30a801..e4edbb25 100644
--- a/backend/src/test/kotlin/com/taskowolf/automation/ActionExecutorTest.kt
+++ b/backend/src/test/kotlin/com/taskowolf/automation/ActionExecutorTest.kt
@@ -60,6 +60,17 @@ class ActionExecutorTest {
     fun `SEND_NOTIFICATION calls notificationService`() {
         val issue = makeIssue()
         executor.execute(listOf(makeAction(ActionType.SEND_NOTIFICATION, """{"message":"Hello"}""")), issue)
-        verify { notificationService.createDirect(any(), NotificationType.AUTOMATION, any(), any(), any()) }
+        verify {
+            notificationService.createDirect(
+                userId = any(),
+                type = NotificationType.AUTOMATION,
+                titleKey = "notification.automation.title",
+                link = any(),
+                titleArgs = any(),
+                bodyKey = any(),
+                bodyArgs = any(),
+                rawBody = "Hello",
+            )
+        }
     }
 }
diff --git a/backend/src/test/kotlin/com/taskowolf/i18n/EmailNotificationMessagesTest.kt b/backend/src/test/kotlin/com/taskowolf/i18n/EmailNotificationMessagesTest.kt
new file mode 100644
index 00000000..30793756
--- /dev/null
+++ b/backend/src/test/kotlin/com/taskowolf/i18n/EmailNotificationMessagesTest.kt
@@ -0,0 +1,56 @@
+package com.taskowolf.i18n
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import org.springframework.context.support.ResourceBundleMessageSource
+import java.util.Locale
+
+class EmailNotificationMessagesTest {
+    private val src = ResourceBundleMessageSource().apply {
+        setBasename("messages"); setDefaultEncoding("UTF-8"); setFallbackToSystemLocale(false)
+    }
+    private fun en(key: String, vararg a: Any?) = src.getMessage(key, a, Locale.ENGLISH)
+    private fun de(key: String, vararg a: Any?) = src.getMessage(key, a, Locale.GERMAN)
+
+    @Test
+    fun `email keys render en and de`() {
+        assertEquals("You were mentioned in WOLF-1", en("email.mention.subject", "WOLF-1"))
+        assertEquals("Sie wurden in WOLF-1 erwähnt", de("email.mention.subject", "WOLF-1"))
+        assertEquals("WOLF-1: My Issue\n\nGreat comment",
+            en("email.mention.body", "WOLF-1", "My Issue", "Great comment"))
+        assertEquals("WOLF-1: My Issue\n\nGreat comment",
+            de("email.mention.body", "WOLF-1", "My Issue", "Great comment"))
+        assertEquals("You were assigned to WOLF-1", en("email.assigned.subject", "WOLF-1"))
+        assertEquals("Ihnen wurde WOLF-1 zugewiesen", de("email.assigned.subject", "WOLF-1"))
+        assertEquals("You have been assigned to: WOLF-1\nMy Issue",
+            en("email.assigned.body", "WOLF-1", "My Issue"))
+        assertEquals("Sie wurden zugewiesen zu: WOLF-1\nMy Issue",
+            de("email.assigned.body", "WOLF-1", "My Issue"))
+    }
+
+    @Test
+    fun `notification title keys render en and de`() {
+        assertEquals("You were mentioned in WOLF-1", en("notification.mention.title", "WOLF-1"))
+        assertEquals("Sie wurden in WOLF-1 erwähnt", de("notification.mention.title", "WOLF-1"))
+        assertEquals("You were assigned to WOLF-1", en("notification.assigned.title", "WOLF-1"))
+        assertEquals("Ihnen wurde WOLF-1 zugewiesen", de("notification.assigned.title", "WOLF-1"))
+        assertEquals("Automation: WOLF-1", en("notification.automation.title", "WOLF-1"))
+        assertEquals("Automatisierung: WOLF-1", de("notification.automation.title", "WOLF-1"))
+    }
+
+    @Test
+    fun `incident and sla keys render en and de (issue key + numeric-as-string)`() {
+        assertEquals("Incident declared: P1 on issue WOLF-1", en("notification.incident.title", "P1", "WOLF-1"))
+        assertEquals("Incident gemeldet: P1 für Vorgang WOLF-1", de("notification.incident.title", "P1", "WOLF-1"))
+        assertEquals("A P1 incident has been declared for issue WOLF-1.",
+            en("notification.incident.body", "P1", "WOLF-1"))
+        assertEquals("Ein P1-Incident wurde für Vorgang WOLF-1 gemeldet.",
+            de("notification.incident.body", "P1", "WOLF-1"))
+        assertEquals("SLA Breached: WOLF-1", en("notification.slaBreached.title", "WOLF-1"))
+        assertEquals("SLA verletzt: WOLF-1", de("notification.slaBreached.title", "WOLF-1"))
+        assertEquals("Issue WOLF-1 has exceeded its SLA resolution time of 1440 minutes.",
+            en("notification.slaBreached.body", "WOLF-1", "1440"))
+        assertEquals("Vorgang WOLF-1 hat seine SLA-Lösungszeit von 1440 Minuten überschritten.",
+            de("notification.slaBreached.body", "WOLF-1", "1440"))
+    }
+}
diff --git a/backend/src/test/kotlin/com/taskowolf/notifications/EmailServiceTest.kt b/backend/src/test/kotlin/com/taskowolf/notifications/EmailServiceTest.kt
index 274103d8..933f11da 100644
--- a/backend/src/test/kotlin/com/taskowolf/notifications/EmailServiceTest.kt
+++ b/backend/src/test/kotlin/com/taskowolf/notifications/EmailServiceTest.kt
@@ -3,78 +3,127 @@ package com.taskowolf.notifications
 import com.taskowolf.auth.domain.User
 import com.taskowolf.comments.domain.Comment
 import com.taskowolf.comments.domain.events.MentionEvent
+import com.taskowolf.core.infrastructure.LocalizedMessages
 import com.taskowolf.issues.domain.Issue
 import com.taskowolf.issues.domain.IssueType
 import com.taskowolf.issues.domain.events.IssueFieldChangedEvent
 import com.taskowolf.notifications.application.EmailService
+import com.taskowolf.notifications.application.NotificationPreferenceService
+import com.taskowolf.notifications.domain.NotificationChannel
+import com.taskowolf.notifications.domain.NotificationType
 import com.taskowolf.projects.domain.Project
 import com.taskowolf.workflows.domain.StatusCategory
 import com.taskowolf.workflows.domain.Workflow
 import com.taskowolf.workflows.domain.WorkflowStatus
 import io.mockk.every
 import io.mockk.mockk
+import io.mockk.slot
 import io.mockk.verify
+import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Test
+import org.springframework.context.support.ResourceBundleMessageSource
 import org.springframework.mail.SimpleMailMessage
 import org.springframework.mail.javamail.JavaMailSender
 
 class EmailServiceTest {
 
+    private val preferences = mockk<NotificationPreferenceService>()
     private val mailSender = mockk<JavaMailSender>(relaxed = true)
-    private val preferences = mockk<com.taskowolf.notifications.application.NotificationPreferenceService>(relaxed = true)
+    private val messageSource = ResourceBundleMessageSource().apply {
+        setBasename("messages"); setDefaultEncoding("UTF-8"); setFallbackToSystemLocale(false)
+    }
+    private val localizedMessages = LocalizedMessages(messageSource)
+    private val service = EmailService(preferences, mailSender, "smtp.test", "TaskWolf <noreply@test.com>", localizedMessages)
 
     private val owner = User(email = "owner@test.com", displayName = "Owner")
-    private val assignee = User(email = "assignee@test.com", displayName = "Assignee")
-    private val actor = User(email = "actor@test.com", displayName = "Actor")
-
-    private val project = Project(key = "WOLF", name = "TaskWolf", owner = owner, workflow = null)
-    private val workflow = Workflow(name = "Default", project = project)
+    private val workflow = Workflow(name = "Default", project = Project(key = "WOLF", name = "TaskWolf", owner = owner, workflow = null))
     private val status = WorkflowStatus("To Do", StatusCategory.TODO, "#6c8fef", 0, workflow)
-    private val issue = Issue(
-        key = "WOLF-1", keyNumber = 1, title = "My Issue",
-        type = IssueType.TASK, status = status, project = project,
-        reporter = owner, assignee = assignee
-    )
+    private val project = Project(key = "WOLF", name = "TaskWolf", owner = owner, workflow = workflow)
+
+    private fun recipient(language: String?) = User(email = "r@test.com", displayName = "R").apply { this.language = language }
+    private fun issueFor(assignee: User?) = Issue(key = "WOLF-1", keyNumber = 1, title = "My Issue",
+        type = IssueType.TASK, status = status, project = project, reporter = owner, assignee = assignee)
+
+    private fun captureMail(): SimpleMailMessage {
+        val slot = slot<SimpleMailMessage>()
+        verify { mailSender.send(capture(slot)) }
+        return slot.captured
+    }
 
     @Test
-    fun `onMention sends email when SMTP host is configured`() {
+    fun `onMention renders subject and body in recipient German`() {
         every { preferences.isEnabled(any(), any(), any()) } returns true
-        val service = EmailService(preferences, mailSender, mailHost = "smtp.example.com", fromAddress = "noreply@example.com")
-        val comment = Comment(issueId = issue.id, authorId = actor.id, body = "Hey @Assignee look at this")
-        val event = MentionEvent(mentionedUser = assignee, comment = comment, issue = issue)
+        val user = recipient("de")
+        val issue = issueFor(assignee = null)
+        val comment = Comment(issueId = issue.id, authorId = owner.id, body = "Great comment")
 
-        service.onMention(event)
+        service.onMention(MentionEvent(mentionedUser = user, comment = comment, issue = issue))
 
-        verify { mailSender.send(any<SimpleMailMessage>()) }
+        val mail = captureMail()
+        assertEquals("Sie wurden in WOLF-1 erwähnt", mail.subject)
+        assertEquals("WOLF-1: My Issue\n\nGreat comment", mail.text)
     }
 
     @Test
-    fun `onMention skips when SMTP host is blank`() {
-        val service = EmailService(preferences, mailSender, mailHost = "", fromAddress = "noreply@example.com")
-        val comment = Comment(issueId = issue.id, authorId = actor.id, body = "Mention")
-        val event = MentionEvent(mentionedUser = assignee, comment = comment, issue = issue)
+    fun `onMention renders subject in English when language null`() {
+        every { preferences.isEnabled(any(), any(), any()) } returns true
+        val user = recipient(null)
+        val issue = issueFor(assignee = null)
+        val comment = Comment(issueId = issue.id, authorId = owner.id, body = "Great comment")
 
-        service.onMention(event)
+        service.onMention(MentionEvent(mentionedUser = user, comment = comment, issue = issue))
 
-        verify(exactly = 0) { mailSender.send(any<SimpleMailMessage>()) }
+        assertEquals("You were mentioned in WOLF-1", captureMail().subject)
     }
 
     @Test
-    fun `onAssigned sends email when assignee changes`() {
+    fun `onAssigned renders subject and body in recipient German`() {
         every { preferences.isEnabled(any(), any(), any()) } returns true
-        val service = EmailService(preferences, mailSender, mailHost = "smtp.example.com", fromAddress = "noreply@example.com")
-        val event = IssueFieldChangedEvent(issue = issue, actor = actor,
+        val assignee = recipient("de")
+        val issue = issueFor(assignee = assignee)
+        val event = IssueFieldChangedEvent(issue = issue, actor = owner,
             field = "assignee", oldValue = null, newValue = assignee.displayName)
 
         service.onAssigned(event)
 
-        verify { mailSender.send(any<SimpleMailMessage>()) }
+        val mail = captureMail()
+        assertEquals("Ihnen wurde WOLF-1 zugewiesen", mail.subject)
+        assertEquals("Sie wurden zugewiesen zu: WOLF-1\nMy Issue", mail.text)
+    }
+
+    @Test
+    fun `onAssigned renders subject in English when language en`() {
+        every { preferences.isEnabled(any(), any(), any()) } returns true
+        val assignee = recipient("en")
+        val issue = issueFor(assignee = assignee)
+        val event = IssueFieldChangedEvent(issue = issue, actor = owner,
+            field = "assignee", oldValue = null, newValue = assignee.displayName)
+
+        service.onAssigned(event)
+
+        assertEquals("You were assigned to WOLF-1", captureMail().subject)
+    }
+
+    // --- Pre-existing guard-condition coverage (predates Phase 3; retained so the
+    // LocalizedMessages constructor change doesn't silently drop this coverage) ---
+
+    @Test
+    fun `onMention skips when SMTP host is blank`() {
+        val blankHostService = EmailService(preferences, mailSender, "", "TaskWolf <noreply@test.com>", localizedMessages)
+        val user = recipient(null)
+        val issue = issueFor(assignee = null)
+        val comment = Comment(issueId = issue.id, authorId = owner.id, body = "Mention")
+
+        blankHostService.onMention(MentionEvent(mentionedUser = user, comment = comment, issue = issue))
+
+        verify(exactly = 0) { mailSender.send(any<SimpleMailMessage>()) }
     }
 
     @Test
     fun `onAssigned skips when field is not assignee`() {
-        val service = EmailService(preferences, mailSender, mailHost = "smtp.example.com", fromAddress = "noreply@example.com")
-        val event = IssueFieldChangedEvent(issue = issue, actor = actor,
+        val assignee = recipient(null)
+        val issue = issueFor(assignee = assignee)
+        val event = IssueFieldChangedEvent(issue = issue, actor = owner,
             field = "title", oldValue = "Old", newValue = "New")
 
         service.onAssigned(event)
@@ -83,15 +132,13 @@ class EmailServiceTest {
     }
 
     @Test
-    fun `onMention skips email when email preference disabled`() {
-        every { preferences.isEnabled(assignee.id,
-            com.taskowolf.notifications.domain.NotificationType.COMMENT_MENTION,
-            com.taskowolf.notifications.domain.NotificationChannel.EMAIL) } returns false
-        val service = EmailService(preferences, mailSender, mailHost = "smtp.example.com", fromAddress = "noreply@example.com")
-        val comment = Comment(issueId = issue.id, authorId = actor.id, body = "Hey @Assignee")
-        val event = MentionEvent(mentionedUser = assignee, comment = comment, issue = issue)
-
-        service.onMention(event)
+    fun `onMention skips email when preference disabled`() {
+        val user = recipient(null)
+        every { preferences.isEnabled(user.id, NotificationType.COMMENT_MENTION, NotificationChannel.EMAIL) } returns false
+        val issue = issueFor(assignee = null)
+        val comment = Comment(issueId = issue.id, authorId = owner.id, body = "Mention")
+
+        service.onMention(MentionEvent(mentionedUser = user, comment = comment, issue = issue))
 
         verify(exactly = 0) { mailSender.send(any<SimpleMailMessage>()) }
     }
diff --git a/backend/src/test/kotlin/com/taskowolf/notifications/NotificationServiceTest.kt b/backend/src/test/kotlin/com/taskowolf/notifications/NotificationServiceTest.kt
index a23c9b4d..d0b32ce7 100644
--- a/backend/src/test/kotlin/com/taskowolf/notifications/NotificationServiceTest.kt
+++ b/backend/src/test/kotlin/com/taskowolf/notifications/NotificationServiceTest.kt
@@ -1,14 +1,17 @@
 package com.taskowolf.notifications
 
 import com.taskowolf.auth.domain.User
+import com.taskowolf.auth.infrastructure.UserRepository
 import com.taskowolf.comments.domain.Comment
 import com.taskowolf.comments.domain.events.MentionEvent
+import com.taskowolf.core.infrastructure.LocalizedMessages
 import com.taskowolf.core.infrastructure.NotFoundException
 import com.taskowolf.issues.domain.Issue
 import com.taskowolf.issues.domain.IssueType
 import com.taskowolf.issues.domain.events.IssueFieldChangedEvent
 import com.taskowolf.notifications.application.NotificationService
 import com.taskowolf.notifications.domain.Notification
+import com.taskowolf.notifications.domain.NotificationChannel
 import com.taskowolf.notifications.domain.NotificationType
 import com.taskowolf.notifications.infrastructure.NotificationRepository
 import com.taskowolf.projects.domain.Project
@@ -19,9 +22,10 @@ import io.mockk.every
 import io.mockk.mockk
 import io.mockk.slot
 import io.mockk.verify
-import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
+import org.springframework.context.support.ResourceBundleMessageSource
 import java.util.Optional
 import java.util.UUID
 
@@ -29,13 +33,17 @@ class NotificationServiceTest {
 
     private val repository = mockk<NotificationRepository>()
     private val preferences = mockk<com.taskowolf.notifications.application.NotificationPreferenceService>()
-    private val service = NotificationService(repository, preferences)
+    private val userRepository = mockk<UserRepository>()
+    private val messageSource = ResourceBundleMessageSource().apply {
+        setBasename("messages"); setDefaultEncoding("UTF-8"); setFallbackToSystemLocale(false)
+    }
+    private val localizedMessages = LocalizedMessages(messageSource)
+    private val service = NotificationService(repository, preferences, localizedMessages, userRepository)
 
     private val user = User(email = "user@test.com", displayName = "User")
     private val actor = User(email = "actor@test.com", displayName = "Actor")
     private val owner = User(email = "owner@test.com", displayName = "Owner")
 
-    // Minimal issue for events — check Workflow constructor before using
     private val workflow = buildWorkflow(owner)
     private val status = WorkflowStatus("To Do", StatusCategory.TODO, "#6c8fef", 0, workflow)
     private val project = Project(key = "WOLF", name = "TaskWolf", owner = owner, workflow = workflow)
@@ -43,7 +51,7 @@ class NotificationServiceTest {
         type = IssueType.TASK, status = status, project = project, reporter = owner, assignee = user)
 
     @Test
-    fun `onMention saves COMMENT_MENTION notification for mentioned user`() {
+    fun `onMention saves COMMENT_MENTION notification with English title for null language`() {
         every { preferences.isEnabled(any(), any(), any()) } returns true
         every { repository.save(any()) } returnsArgument 0
         val comment = Comment(issueId = issue.id, authorId = actor.id, body = "Hey @User check this")
@@ -55,10 +63,27 @@ class NotificationServiceTest {
         verify { repository.save(capture(slot)) }
         assertEquals(user.id, slot.captured.userId)
         assertEquals(NotificationType.COMMENT_MENTION, slot.captured.type)
+        assertEquals("You were mentioned in WOLF-1", slot.captured.title)
+        assertEquals("Hey @User check this", slot.captured.body) // user-content body unchanged
     }
 
     @Test
-    fun `onIssueFieldChanged saves ISSUE_ASSIGNED notification when assignee changes`() {
+    fun `onMention renders title in recipient German`() {
+        every { preferences.isEnabled(any(), any(), any()) } returns true
+        every { repository.save(any()) } returnsArgument 0
+        val germanUser = User(email = "de@test.com", displayName = "DE").apply { language = "de" }
+        val comment = Comment(issueId = issue.id, authorId = actor.id, body = "Hallo")
+        val event = MentionEvent(mentionedUser = germanUser, comment = comment, issue = issue)
+
+        service.onMention(event)
+
+        val slot = slot<Notification>()
+        verify { repository.save(capture(slot)) }
+        assertEquals("Sie wurden in WOLF-1 erwähnt", slot.captured.title)
+    }
+
+    @Test
+    fun `onIssueFieldChanged saves ISSUE_ASSIGNED with localized title, body unchanged`() {
         every { preferences.isEnabled(any(), any(), any()) } returns true
         every { repository.save(any()) } returnsArgument 0
         val event = IssueFieldChangedEvent(issue = issue, actor = actor,
@@ -70,12 +95,13 @@ class NotificationServiceTest {
         verify { repository.save(capture(slot)) }
         assertEquals(user.id, slot.captured.userId)
         assertEquals(NotificationType.ISSUE_ASSIGNED, slot.captured.type)
+        assertEquals("You were assigned to WOLF-1", slot.captured.title)
+        assertEquals("Test Issue", slot.captured.body) // issue.title stays as user-content
     }
 
     @Test
     fun `onMention skips save when in-app preference disabled`() {
-        every { preferences.isEnabled(user.id, NotificationType.COMMENT_MENTION,
-            com.taskowolf.notifications.domain.NotificationChannel.IN_APP) } returns false
+        every { preferences.isEnabled(user.id, NotificationType.COMMENT_MENTION, NotificationChannel.IN_APP) } returns false
         val comment = Comment(issueId = issue.id, authorId = actor.id, body = "Hey @User")
         val event = MentionEvent(mentionedUser = user, comment = comment, issue = issue)
 
@@ -84,14 +110,84 @@ class NotificationServiceTest {
         verify(exactly = 0) { repository.save(any()) }
     }
 
+    @Test
+    fun `createDirect renders templated body in recipient German`() {
+        val germanUser = User(email = "de@test.com", displayName = "DE").apply { language = "de" }
+        every { preferences.isEnabled(germanUser.id, NotificationType.SLA_BREACHED, NotificationChannel.IN_APP) } returns true
+        every { userRepository.findById(germanUser.id) } returns Optional.of(germanUser)
+        every { repository.save(any()) } returnsArgument 0
+
+        service.createDirect(
+            userId = germanUser.id,
+            type = NotificationType.SLA_BREACHED,
+            titleKey = "notification.slaBreached.title",
+            link = "/issues/WOLF-1",
+            titleArgs = arrayOf("WOLF-1"),
+            bodyKey = "notification.slaBreached.body",
+            bodyArgs = arrayOf("WOLF-1", "60"),
+        )
+
+        val slot = slot<Notification>()
+        verify { repository.save(capture(slot)) }
+        assertEquals("SLA verletzt: WOLF-1", slot.captured.title)
+        assertEquals("Vorgang WOLF-1 hat seine SLA-Lösungszeit von 60 Minuten überschritten.", slot.captured.body)
+    }
+
+    @Test
+    fun `createDirect keeps rawBody as user-content and renders title`() {
+        every { preferences.isEnabled(user.id, NotificationType.AUTOMATION, NotificationChannel.IN_APP) } returns true
+        every { userRepository.findById(user.id) } returns Optional.of(user)
+        every { repository.save(any()) } returnsArgument 0
+
+        service.createDirect(
+            userId = user.id,
+            type = NotificationType.AUTOMATION,
+            titleKey = "notification.automation.title",
+            link = "/l",
+            titleArgs = arrayOf("WOLF-1"),
+            rawBody = "Custom automation message",
+        )
+
+        val slot = slot<Notification>()
+        verify { repository.save(capture(slot)) }
+        assertEquals("Automation: WOLF-1", slot.captured.title)
+        assertEquals("Custom automation message", slot.captured.body)
+    }
+
+    @Test
+    fun `createDirect falls back to English when recipient user not found`() {
+        every { preferences.isEnabled(user.id, NotificationType.AUTOMATION, NotificationChannel.IN_APP) } returns true
+        every { userRepository.findById(user.id) } returns Optional.empty()
+        every { repository.save(any()) } returnsArgument 0
+
+        service.createDirect(
+            userId = user.id,
+            type = NotificationType.AUTOMATION,
+            titleKey = "notification.automation.title",
+            link = "/l",
+            titleArgs = arrayOf("WOLF-1"),
+            rawBody = "msg",
+        )
+
+        val slot = slot<Notification>()
+        verify { repository.save(capture(slot)) }
+        assertEquals("Automation: WOLF-1", slot.captured.title)
+    }
+
     @Test
     fun `createDirect skips save when in-app preference disabled`() {
-        every { preferences.isEnabled(user.id, NotificationType.AUTOMATION,
-            com.taskowolf.notifications.domain.NotificationChannel.IN_APP) } returns false
+        every { preferences.isEnabled(user.id, NotificationType.AUTOMATION, NotificationChannel.IN_APP) } returns false
 
-        service.createDirect(user.id, NotificationType.AUTOMATION, "t", "b", "/l")
+        service.createDirect(
+            userId = user.id,
+            type = NotificationType.AUTOMATION,
+            titleKey = "notification.automation.title",
+            link = "/l",
+            titleArgs = arrayOf("WOLF-1"),
+        )
 
         verify(exactly = 0) { repository.save(any()) }
+        verify(exactly = 0) { userRepository.findById(any()) }
     }
 
     @Test
diff --git a/backend/src/test/kotlin/com/taskowolf/servicedesk/IncidentServiceTest.kt b/backend/src/test/kotlin/com/taskowolf/servicedesk/IncidentServiceTest.kt
index deb9c21f..18f5fd4b 100644
--- a/backend/src/test/kotlin/com/taskowolf/servicedesk/IncidentServiceTest.kt
+++ b/backend/src/test/kotlin/com/taskowolf/servicedesk/IncidentServiceTest.kt
@@ -2,6 +2,8 @@ package com.taskowolf.servicedesk
 
 import com.taskowolf.comments.domain.Comment
 import com.taskowolf.comments.infrastructure.CommentRepository
+import com.taskowolf.issues.domain.Issue
+import com.taskowolf.issues.infrastructure.IssueRepository
 import com.taskowolf.notifications.application.NotificationService
 import com.taskowolf.notifications.domain.NotificationType
 import com.taskowolf.servicedesk.application.IncidentService
@@ -24,34 +26,49 @@ class IncidentServiceTest {
     private val incidentRepo = mockk<IncidentRepository>()
     private val commentRepo = mockk<CommentRepository>()
     private val notificationService = mockk<NotificationService>(relaxed = true)
-    private val service = IncidentService(incidentRepo, commentRepo, notificationService)
+    private val issueRepository = mockk<IssueRepository>()
+    private val service = IncidentService(incidentRepo, commentRepo, notificationService, issueRepository)
 
     private val issueId = UUID.randomUUID()
 
     @Test
-    fun `create saves incident and notifies users`() {
+    fun `create saves incident and notifies users with issue key`() {
         val onCallId = UUID.randomUUID()
         val notifyId1 = UUID.randomUUID()
         val notifyId2 = UUID.randomUUID()
         every { incidentRepo.save(any()) } returnsArgument 0
+        val issue = mockk<Issue> { every { key } returns "WOLF-1" }
+        every { issueRepository.findById(issueId) } returns Optional.of(issue)
 
         val incident = service.create(issueId, IncidentSeverity.P1, onCallId, listOf(notifyId1, notifyId2))
 
         assertEquals(issueId, incident.issueId)
         assertEquals(IncidentSeverity.P1, incident.severity)
         assertEquals(onCallId, incident.onCallAssigneeId)
-        verify(exactly = 2) { notificationService.createDirect(any(), NotificationType.AUTOMATION, any(), any(), any()) }
+        verify(exactly = 2) {
+            notificationService.createDirect(
+                userId = any(),
+                type = NotificationType.AUTOMATION,
+                titleKey = "notification.incident.title",
+                link = "/issues/WOLF-1",
+                titleArgs = match { it.contains("WOLF-1") },
+                bodyKey = "notification.incident.body",
+                bodyArgs = match { it.contains("WOLF-1") },
+                rawBody = any(),
+            )
+        }
     }
 
     @Test
-    fun `create without notify users saves incident without notifications`() {
+    fun `create without notify users saves incident without notifications or issue lookup`() {
         every { incidentRepo.save(any()) } returnsArgument 0
 
         val incident = service.create(issueId, IncidentSeverity.P2, null, emptyList())
 
         assertEquals(issueId, incident.issueId)
         assertEquals(IncidentSeverity.P2, incident.severity)
-        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any(), any()) }
+        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any()) }
+        verify(exactly = 0) { issueRepository.findById(any()) }
     }
 
     @Test
diff --git a/backend/src/test/kotlin/com/taskowolf/servicedesk/SlaMonitorJobTest.kt b/backend/src/test/kotlin/com/taskowolf/servicedesk/SlaMonitorJobTest.kt
index cc072fb6..9d6f0eb9 100644
--- a/backend/src/test/kotlin/com/taskowolf/servicedesk/SlaMonitorJobTest.kt
+++ b/backend/src/test/kotlin/com/taskowolf/servicedesk/SlaMonitorJobTest.kt
@@ -72,7 +72,7 @@ class SlaMonitorJobTest {
 
         job.run()
 
-        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any(), any()) }
+        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any()) }
         verify(exactly = 0) { auditService.log(any(), any(), any()) }
     }
 
@@ -96,11 +96,14 @@ class SlaMonitorJobTest {
 
         verify(exactly = 1) {
             notificationService.createDirect(
-                notifyUserId,
-                NotificationType.SLA_BREACHED,
-                match { it.contains("WOLF-1") },
-                any(),
-                any()
+                userId = notifyUserId,
+                type = NotificationType.SLA_BREACHED,
+                titleKey = "notification.slaBreached.title",
+                link = "/issues/WOLF-1",
+                titleArgs = match { it.contains("WOLF-1") },
+                bodyKey = "notification.slaBreached.body",
+                bodyArgs = any(),
+                rawBody = any(),
             )
         }
         verify(exactly = 1) {
@@ -122,7 +125,7 @@ class SlaMonitorJobTest {
 
         job.run()
 
-        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any(), any()) }
+        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any()) }
     }
 
     @Test
@@ -136,7 +139,7 @@ class SlaMonitorJobTest {
 
         job.run()
 
-        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any(), any()) }
+        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any()) }
     }
 
     @Test
@@ -145,7 +148,7 @@ class SlaMonitorJobTest {
 
         job.run()
 
-        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any(), any()) }
+        verify(exactly = 0) { notificationService.createDirect(any(), any(), any(), any()) }
         verify(exactly = 0) { auditService.log(any(), any(), any()) }
     }