Add support for the diminished state.

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/campaign/CampaignRepository.kt

@@ -32,8 +32,8 @@ class CampaignRepository(
     }
 
     fun characterInstance(
-        chracterInstanceId: Campaign.CharacterInstance.Id,
+        characterInstanceId: Campaign.CharacterInstance.Id,
     ): Campaign.CharacterInstance {
-        return campaignFlow.value.character(chracterInstanceId)
+        return campaignFlow.value.character(characterInstanceId)
     }
 }

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/repository/campaign/CampaignStore.kt

@@ -5,9 +5,10 @@ import com.pixelized.desktop.lwa.repository.network.NetworkRepository
 import com.pixelized.shared.lwa.model.campaign.Campaign
 import com.pixelized.shared.lwa.model.campaign.CampaignJsonFactory
 import com.pixelized.shared.lwa.model.campaign.character
+import com.pixelized.shared.lwa.model.campaign.npc
 import com.pixelized.shared.lwa.protocol.websocket.Message
+import com.pixelized.shared.lwa.protocol.websocket.payload.CampaignMessage
 import com.pixelized.shared.lwa.protocol.websocket.payload.RestSynchronisation
-import com.pixelized.shared.lwa.protocol.websocket.payload.UpdatePlayerCharacteristicMessage
 import com.pixelized.shared.lwa.usecase.CampaignUseCase
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
@@ -46,21 +47,7 @@ class CampaignStore(
         return data
     }
 
-    private fun updateCharacteristic(
+    // region : WebSocket message Handling.
-        characterId: Campaign.CharacterInstance.Id,
-        characteristic: Campaign.CharacterInstance.Characteristic,
-        value: Int,
-    ) {
-        val campaign = _campaignFlow.value
-        val characters = campaign.characters.toMutableMap().also {
-            it[characterId] = useCase.updateCharacteristic(
-                character = campaign.character(id = characterId),
-                characteristic = characteristic,
-                value = value
-            )
-        }
-        _campaignFlow.value = _campaignFlow.value.copy(characters = characters)
-    }
 
     private suspend fun handleMessage(message: Message) {
         when (val payload = message.value) {
@@ -68,17 +55,89 @@ class CampaignStore(
                 update()
             }
 
-            is UpdatePlayerCharacteristicMessage -> {
+            is CampaignMessage -> {
-                val id = factory.convertFromV1(characterInstanceIdJson = payload.characterInstanceId)
+                val instanceId = Campaign.CharacterInstance.Id(
-                val characteristic = factory.convertFromV1(characteristicJson = payload.characteristic)
+                    characterSheetId = payload.characterSheetId,
-                updateCharacteristic(
+                    instanceId = payload.instanceId,
-                    characterId = id,
-                    characteristic = characteristic,
-                    value = payload.value,
                 )
+                when (payload) {
+                    is CampaignMessage.UpdateCharacteristic -> updateCharacteristic(
+                        characterInstanceId = instanceId,
+                        characteristic = factory.convertFromV1(characteristicJson = payload.characteristic),
+                        value = payload.value,
+                    )
+
+                    is CampaignMessage.UpdateDiminished -> updateDiminished(
+                        characterInstanceId = instanceId,
+                        diminished = payload.diminished,
+                    )
+                }
             }
 
             else -> Unit
         }
     }
-}
+
+    private fun updateCharacteristic(
+        characterInstanceId: Campaign.CharacterInstance.Id,
+        characteristic: Campaign.CharacterInstance.Characteristic,
+        value: Int,
+    ) {
+        val campaign = _campaignFlow.value
+
+        when {
+            campaign.characters.containsKey(characterInstanceId) -> {
+                val characters = campaign.characters.toMutableMap().also {
+                    it[characterInstanceId] = useCase.updateCharacteristic(
+                        instance = campaign.character(id = characterInstanceId),
+                        characteristic = characteristic,
+                        value = value
+                    )
+                }
+                _campaignFlow.value = _campaignFlow.value.copy(characters = characters)
+            }
+
+            campaign.npcs.containsKey(characterInstanceId) -> {
+                val npcs = campaign.npcs.toMutableMap().also {
+                    it[characterInstanceId] = useCase.updateCharacteristic(
+                        instance = campaign.npc(id = characterInstanceId),
+                        characteristic = characteristic,
+                        value = value
+                    )
+                }
+                _campaignFlow.value = _campaignFlow.value.copy(npcs = npcs)
+            }
+        }
+    }
+
+    private fun updateDiminished(
+        characterInstanceId: Campaign.CharacterInstance.Id,
+        diminished: Int,
+    ) {
+        val campaign = _campaignFlow.value
+
+        when {
+            campaign.characters.containsKey(characterInstanceId) -> {
+                val characters = campaign.characters.toMutableMap().also {
+                    it[characterInstanceId] = useCase.updateDiminished(
+                        instance = campaign.character(id = characterInstanceId),
+                        diminished = diminished,
+                    )
+                }
+                _campaignFlow.value = _campaignFlow.value.copy(characters = characters)
+            }
+
+            campaign.npcs.containsKey(characterInstanceId) -> {
+                val npcs = campaign.npcs.toMutableMap().also {
+                    it[characterInstanceId] = useCase.updateDiminished(
+                        instance = campaign.npc(id = characterInstanceId),
+                        diminished = diminished,
+                    )
+                }
+                _campaignFlow.value = _campaignFlow.value.copy(npcs = npcs)
+            }
+        }
+    }
+
+    // endregion
+}

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/ui/composable/character/characteristic/CharacterDetailCharacteristicDialogViewModel.kt

@@ -13,7 +13,7 @@ import com.pixelized.shared.lwa.model.campaign.Campaign
 import com.pixelized.shared.lwa.model.campaign.Campaign.CharacterInstance.Characteristic
 import com.pixelized.shared.lwa.model.campaign.CampaignJsonFactory
 import com.pixelized.shared.lwa.model.characterSheet.CharacterSheet
-import com.pixelized.shared.lwa.protocol.websocket.payload.UpdatePlayerCharacteristicMessage
+import com.pixelized.shared.lwa.protocol.websocket.payload.CampaignMessage
 
 class CharacterDetailCharacteristicDialogViewModel(
     private val characterSheetRepository: CharacterSheetRepository,
@@ -42,7 +42,7 @@ class CharacterDetailCharacteristicDialogViewModel(
             characterSheetId = characterInstanceId.characterSheetId,
         )
         val characterInstance: Campaign.CharacterInstance = campaignRepository.characterInstance(
-            chracterInstanceId = characterInstanceId,
+            characterInstanceId = characterInstanceId,
         )
         val alterations: Map<String, List<FieldAlteration>> = alterationRepository.alterations(
             characterInstanceId = characterInstanceId,
@@ -61,42 +61,33 @@ class CharacterDetailCharacteristicDialogViewModel(
         characteristic: Characteristic,
         value: Int,
     ) {
-        // fetch the linked character sheet
+        // fetch the linked character sheet, if null stop exit this function.
         val sheet = characterSheetRepository.characterDetail(
             characterSheetId = characterInstanceId.characterSheetId,
-        )
+        ) ?: return
         val alterations = alterationRepository.alterations(
             characterInstanceId = characterInstanceId,
         )
         // we need the maximum HP / Power that the character sheet have.
-        if (sheet != null) {
+        val alteredSheet = alteredCharacterSheetFactory.sheet(
-            val alteredSheet = alteredCharacterSheetFactory.sheet(
+            characterSheet = sheet,
-                characterSheet = sheet,
+            alterations = alterations,
-                alterations = alterations,
+        )
-            )
+        // convert the data to json format
-            // convert the data to json format
+        val characteristicJson = campaignJsonFactory.convertToJson(
-            val characterInstanceIdJson = campaignJsonFactory.convertToJson(
+            characteristic = characteristic,
-                id = characterInstanceId,
+        )
-            )
+        // share the data through the websocket.
-            val characteristicJson = campaignJsonFactory.convertToJson(
+        network.share(
-                characteristic = characteristic,
+            payload = CampaignMessage.UpdateCharacteristic(
-            )
+                characterSheetId = characterInstanceId.characterSheetId,
-            // share the data through the websocket.
+                instanceId = characterInstanceId.instanceId,
-            network.share(
+                characteristic = characteristicJson,
-                payload = UpdatePlayerCharacteristicMessage(
+                value = when (characteristic) {
-                    characterInstanceId = characterInstanceIdJson,
+                    Characteristic.Damage -> alteredSheet.maxHp - value
-                    characteristic = characteristicJson,
+                    Characteristic.Power -> alteredSheet.maxPp - value
-                    value = when (characteristic) {
+                },
-                        Characteristic.Damage -> {
+            ),
-                            alteredSheet.maxHp - value
+        )
-                        }
-
-                        Characteristic.Power -> {
-                            alteredSheet.maxPp - value
-                        }
-                    },
-                ),
-            )
-        }
     }
 }

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/ui/screen/campaign/CampaignScreen.kt

@@ -181,11 +181,13 @@ fun CampaignScreen(
         DiminishedStatDialog(
             dialog = dismissedViewModel.diminishedDialog,
             onConfirm = { diminished ->
-                dismissedViewModel.changeDiminished(
+                scope.launch {
-                    dialog = diminished
+                    dismissedViewModel.changeDiminished(
-                )
+                        dialog = diminished
-                blurController.hide()
+                    )
-                dismissedViewModel.hideDiminishedDialog()
+                    blurController.hide()
+                    dismissedViewModel.hideDiminishedDialog()
+                }
             },
             onDismissRequest = {
                 blurController.hide()

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/ui/screen/campaign/player/detail/CharacterDetailFactory.kt

@@ -55,6 +55,7 @@ class CharacterDetailFactory(
         return CharacterDetailHeaderUio(
             id = characterInstanceId,
             portrait = alteredCharacterSheet.portrait,
+            diminished = characterInstance.diminished,
             name = alteredCharacterSheet.name,
             hp = "${maxHp - characterInstance.damage}",
             maxHp = "$maxHp",
@@ -71,6 +72,7 @@ class CharacterDetailFactory(
     suspend fun convertToCharacterDetailSheetUio(
         characterInstanceId: Campaign.CharacterInstance.Id,
         characterSheet: CharacterSheet?,
+        characterInstance: Campaign.CharacterInstance,
         alterations: Map<String, List<FieldAlteration>>,
     ): CharacterDetailSheetUio? {
         if (characterSheet == null) return null
@@ -94,7 +96,7 @@ class CharacterDetailFactory(
                         characterSheetId = characterSheet.id,
                         label = getString(Res.string.character_sheet__characteristics__str),
                         rollAction = "1d100",
-                        rollSuccessValue = alteredCharacterSheet.strength * 5,
+                        rollSuccessValue = alteredCharacterSheet.strength * 5 - characterInstance.diminished,
                     ),
                 ),
                 CharacterDetailSheetCharacteristicUio(
@@ -108,7 +110,7 @@ class CharacterDetailFactory(
                         characterSheetId = characterSheet.id,
                         label = getString(Res.string.character_sheet__characteristics__dex),
                         rollAction = "1d100",
-                        rollSuccessValue = alteredCharacterSheet.dexterity * 5,
+                        rollSuccessValue = alteredCharacterSheet.dexterity * 5 - characterInstance.diminished,
                     ),
                 ),
                 CharacterDetailSheetCharacteristicUio(
@@ -122,7 +124,7 @@ class CharacterDetailFactory(
                         characterSheetId = characterSheet.id,
                         label = getString(Res.string.character_sheet__characteristics__con),
                         rollAction = "1d100",
-                        rollSuccessValue = alteredCharacterSheet.constitution * 5,
+                        rollSuccessValue = alteredCharacterSheet.constitution * 5 - characterInstance.diminished,
                     ),
                 ),
                 CharacterDetailSheetCharacteristicUio(
@@ -136,7 +138,7 @@ class CharacterDetailFactory(
                         characterSheetId = characterSheet.id,
                         label = getString(Res.string.character_sheet__characteristics__hei),
                         rollAction = "1d100",
-                        rollSuccessValue = alteredCharacterSheet.height * 5,
+                        rollSuccessValue = alteredCharacterSheet.height * 5 - characterInstance.diminished,
                     ),
                 ),
                 CharacterDetailSheetCharacteristicUio(
@@ -150,7 +152,7 @@ class CharacterDetailFactory(
                         characterSheetId = characterSheet.id,
                         label = getString(Res.string.character_sheet__characteristics__int),
                         rollAction = "1d100",
-                        rollSuccessValue = alteredCharacterSheet.intelligence * 5,
+                        rollSuccessValue = alteredCharacterSheet.intelligence * 5 - characterInstance.diminished,
                     ),
                 ),
                 CharacterDetailSheetCharacteristicUio(
@@ -164,7 +166,7 @@ class CharacterDetailFactory(
                         characterSheetId = characterSheet.id,
                         label = getString(Res.string.character_sheet__characteristics__pow),
                         rollAction = "1d100",
-                        rollSuccessValue = alteredCharacterSheet.power * 5,
+                        rollSuccessValue = alteredCharacterSheet.power * 5 - characterInstance.diminished,
                     ),
                 ),
                 CharacterDetailSheetCharacteristicUio(
@@ -178,7 +180,7 @@ class CharacterDetailFactory(
                         characterSheetId = characterSheet.id,
                         label = getString(Res.string.character_sheet__characteristics__cha),
                         rollAction = "1d100",
-                        rollSuccessValue = alteredCharacterSheet.charisma * 5,
+                        rollSuccessValue = alteredCharacterSheet.charisma * 5 - characterInstance.diminished,
                     ),
                 ),
             ),
@@ -186,6 +188,7 @@ class CharacterDetailFactory(
                 val value = expressionUseCase.computeSkillValue(
                     sheet = characterSheet,
                     skill = skill,
+                    diminished = characterInstance.diminished,
                     alterations = alterations,
                 )
                 CharacterDetailSheetSkillUio(
@@ -212,6 +215,7 @@ class CharacterDetailFactory(
                 val value = expressionUseCase.computeSkillValue(
                     sheet = characterSheet,
                     skill = skill,
+                    diminished = characterInstance.diminished,
                     alterations = alterations,
                 )
                 CharacterDetailSheetSkillUio(
@@ -238,6 +242,7 @@ class CharacterDetailFactory(
                 val value = expressionUseCase.computeSkillValue(
                     sheet = characterSheet,
                     skill = skill,
+                    diminished = characterInstance.diminished,
                     alterations = alterations,
                 )
                 CharacterDetailSheetSkillUio(

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/ui/screen/campaign/player/detail/CharacterDetailViewModel.kt

@@ -47,12 +47,14 @@ class CharacterDetailViewModel(
                     initialValue = null,
                 ),
                 sheet = combine(
+                    campaignRepository.characterInstanceFlow(id = characterInstanceId),
                     characterSheetRepository.characterDetailFlow(characterId = characterInstanceId.characterSheetId),
                     alterationRepository.alterationsFlow(characterId = characterInstanceId),
-                ) { characterSheet, alterations ->
+                ) { characterInstance, characterSheet, alterations ->
                     characterDetailFactory.convertToCharacterDetailSheetUio(
                         characterInstanceId = characterInstanceId,
                         characterSheet = characterSheet,
+                        characterInstance = characterInstance,
                         alterations = alterations,
                     )
                 }.stateIn(

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/ui/screen/campaign/player/detail/CharacterDiminishedViewModel.kt

@@ -5,31 +5,37 @@ import androidx.compose.runtime.mutableStateOf
 import androidx.compose.ui.text.TextRange
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.lifecycle.ViewModel
-import com.pixelized.desktop.lwa.repository.characterSheet.CharacterSheetRepository
+import com.pixelized.desktop.lwa.repository.campaign.CampaignRepository
+import com.pixelized.desktop.lwa.repository.network.NetworkRepository
 import com.pixelized.desktop.lwa.ui.screen.characterSheet.detail.dialog.DiminishedStatDialogUio
 import com.pixelized.shared.lwa.model.campaign.Campaign
+import com.pixelized.shared.lwa.protocol.websocket.payload.CampaignMessage
 import lwacharactersheet.composeapp.generated.resources.Res
 import lwacharactersheet.composeapp.generated.resources.character_sheet__diminished__label
 import org.jetbrains.compose.resources.getString
 
 class CharacterDiminishedViewModel(
-    private val characterSheetRepository: CharacterSheetRepository,
+    private val campaignRepository: CampaignRepository,
+    private val networkRepository: NetworkRepository,
 ) : ViewModel() {
 
     private val _diminishedDialog = mutableStateOf<DiminishedStatDialogUio?>(null)
     val diminishedDialog: State<DiminishedStatDialogUio?> get() = _diminishedDialog
 
     suspend fun showDiminishedDialog(
-        characterInstanceId: Campaign.CharacterInstance.Id?,
+        characterInstanceId: Campaign.CharacterInstance.Id,
     ) {
-        if (characterInstanceId == null) return
+        val characterInstance = campaignRepository.characterInstance(
-
+            characterInstanceId = characterInstanceId,
-        val diminished = 0 // TODO repository.characterDiminishedFlow(id = id).value
+        )
         val textFieldValue = mutableStateOf(
-            TextFieldValue("$diminished", selection = TextRange(index = 0))
+            TextFieldValue(
+                text = "${characterInstance.diminished}",
+                selection = TextRange(index = 0),
+            )
         )
         _diminishedDialog.value = DiminishedStatDialogUio(
-            id = characterInstanceId,
+            characterInstanceId = characterInstanceId,
             label = getString(resource = Res.string.character_sheet__diminished__label),
             value = { textFieldValue.value },
             onValueChange = { value ->
@@ -45,12 +51,16 @@ class CharacterDiminishedViewModel(
         _diminishedDialog.value = null
     }
 
-    fun changeDiminished(dialog: DiminishedStatDialogUio) {
+    suspend fun changeDiminished(
-        val value = dialog.value().text.toIntOrNull() ?: 0
+        dialog: DiminishedStatDialogUio,
-        // TODO
+    ) {
-//        repository.setDiminishedForCharacter(
+        val diminished = dialog.value().text.toIntOrNull() ?: 0
-//            id = dialog.id,
+        networkRepository.share(
-//            diminished = value,
+            payload = CampaignMessage.UpdateDiminished(
-//        )
+                characterSheetId = dialog.characterInstanceId.characterSheetId,
+                instanceId = dialog.characterInstanceId.instanceId,
+                diminished = diminished,
+            )
+        )
     }
 }

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/ui/screen/campaign/player/detail/header/CharacterDetailHeader.kt

@@ -1,17 +1,28 @@
 package com.pixelized.desktop.lwa.ui.screen.campaign.player.detail.header
 
+import androidx.compose.animation.AnimatedContent
+import androidx.compose.animation.SizeTransform
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.animation.slideInVertically
+import androidx.compose.animation.slideOutVertically
+import androidx.compose.animation.togetherWith
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.material.Icon
 import androidx.compose.material.IconButton
 import androidx.compose.material.MaterialTheme
 import androidx.compose.material.Text
+import androidx.compose.material.minimumInteractiveComponentSize
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Stable
 import androidx.compose.runtime.State
@@ -19,6 +30,7 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
@@ -40,6 +52,7 @@ import org.jetbrains.compose.resources.painterResource
 data class CharacterDetailHeaderUio(
     val id: Campaign.CharacterInstance.Id,
     val portrait: String?,
+    val diminished: Int,
     val name: String,
     val hp: String,
     val maxHp: String,
@@ -74,15 +87,35 @@ fun CharacterDetailHeader(
                 overflow = TextOverflow.Ellipsis,
                 maxLines = 1,
             )
-            IconButton(
+            Box {
-                onClick = onDiminished,
+                IconButton(
-            ) {
+                    onClick = onDiminished,
-                Icon(
+                ) {
-                    modifier = Modifier.size(size = 24.dp),
+                    Icon(
-                    painter = painterResource(Res.drawable.ic_skull_24dp),
+                        modifier = Modifier.size(size = 24.dp),
-                    tint = MaterialTheme.colors.primary,
+                        painter = painterResource(Res.drawable.ic_skull_24dp),
-                    contentDescription = null,
+                        tint = MaterialTheme.colors.primary,
-                )
+                        contentDescription = null,
+                    )
+                }
+                AnimatedContent(
+                    modifier = Modifier.align(alignment = Alignment.BottomCenter),
+                    targetState = header.value?.diminished,
+                    transitionSpec = {
+                        val sign = if ((targetState ?: 0) > (initialState ?: 0)) 1 else -1
+                        val enter = fadeIn() + slideInVertically { 16 * sign }
+                        val exit = fadeOut() + slideOutVertically { -16 * sign }
+                        enter togetherWith exit using SizeTransform(clip = false)
+                    }
+                ) {
+                    Text(
+                        modifier = Modifier.width(width = 48.dp),
+                        style = MaterialTheme.typography.caption,
+                        color = MaterialTheme.colors.onSurface,
+                        textAlign = TextAlign.Center,
+                        text = "${it?.takeIf { it > 0 } ?: "  "}",
+                    )
+                }
             }
             IconButton(
                 onClick = onDismissRequest,

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/ui/screen/characterSheet/detail/CharacterSheetFactory.kt

@@ -216,6 +216,7 @@ class CharacterSheetFactory(
                     value = skillUseCase.computeSkillValue(
                         sheet = characterSheet,
                         skill = skill,
+                        diminished = instance.diminished,
                         alterations = alterations,
                     ),
                     tooltips = skill.description?.let {
@@ -240,6 +241,7 @@ class CharacterSheetFactory(
                     value = skillUseCase.computeSkillValue(
                         sheet = characterSheet,
                         skill = skill,
+                        diminished = instance.diminished,
                         alterations = alterations,
                     ),
                     used = skill.used,
@@ -258,6 +260,7 @@ class CharacterSheetFactory(
                     value = skillUseCase.computeSkillValue(
                         sheet = characterSheet,
                         skill = skill,
+                        diminished = instance.diminished,
                         alterations = alterations,
                     ),
                     used = skill.used,

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/ui/screen/characterSheet/detail/dialog/DiminishedStatDialog.kt

@@ -50,7 +50,7 @@ import org.jetbrains.compose.resources.stringResource
 
 @Stable
 data class DiminishedStatDialogUio(
-    val id: Campaign.CharacterInstance.Id,
+    val characterInstanceId: Campaign.CharacterInstance.Id,
     val label: String,
     val value: () -> TextFieldValue,
     val onValueChange: (TextFieldValue) -> Unit,

server/src/main/kotlin/com/pixelized/server/lwa/model/campaign/CampaignService.kt

@@ -103,41 +103,77 @@ class CampaignService(
 
     // Data manipulation through WebSocket.
 
-    suspend fun updateCharacterCharacteristic(
+    suspend fun updateCharacteristic(
         characterInstanceId: Campaign.CharacterInstance.Id,
         characteristic: Campaign.CharacterInstance.Characteristic,
         value: Int,
     ) {
-        // fetch all the current campaign character
+        when {
-        val characters = campaign.characters.toMutableMap()
+            campaign.characters.containsKey(characterInstanceId) -> {
-        // update the corresponding character using the use case.
+                // fetch all the current campaign character
-        characters[characterInstanceId] = useCase.updateCharacteristic(
+                val characters = campaign.characters.toMutableMap()
-            character = campaign.character(id = characterInstanceId),
+                // update the corresponding character using the use case.
-            characteristic = characteristic,
+                characters[characterInstanceId] = useCase.updateCharacteristic(
-            value = value,
+                    instance = campaign.character(id = characterInstanceId),
-        )
+                    characteristic = characteristic,
-        // save the campaign to the disk + update the flow.
+                    value = value,
-        store.save(
+                )
-            campaign = campaign.copy(characters = characters)
+                // save the campaign to the disk + update the flow.
-        )
+                store.save(
+                    campaign = campaign.copy(characters = characters)
+                )
+            }
+
+            campaign.npcs.containsKey(characterInstanceId) -> {
+                // fetch all the current campaign character
+                val npcs = campaign.npcs.toMutableMap()
+                // update the corresponding character using the use case.
+                npcs[characterInstanceId] = useCase.updateCharacteristic(
+                    instance = campaign.npc(id = characterInstanceId),
+                    characteristic = characteristic,
+                    value = value,
+                )
+                // save the campaign to the disk + update the flow.
+                store.save(
+                    campaign = campaign.copy(npcs = npcs)
+                )
+            }
+        }
     }
 
-    suspend fun updateNpcCharacteristic(
+    suspend fun updateDiminished(
-        npcInstanceId: Campaign.CharacterInstance.Id,
+        characterInstanceId: Campaign.CharacterInstance.Id,
-        characteristic: Campaign.CharacterInstance.Characteristic,
+        diminished: Int,
-        value: Int,
     ) {
-        // fetch all the current campaign character
+        when {
-        val npcs = campaign.npcs.toMutableMap()
+            campaign.characters.containsKey(characterInstanceId) -> {
-        // update the corresponding character using the use case.
+                // fetch all the current campaign character
-        npcs[npcInstanceId] = useCase.updateCharacteristic(
+                val characters = campaign.characters.toMutableMap()
-            character = campaign.npc(id = npcInstanceId),
+                // update the corresponding character using the use case.
-            characteristic = characteristic,
+                characters[characterInstanceId] = useCase.updateDiminished(
-            value = value,
+                    instance = campaign.character(id = characterInstanceId),
-        )
+                    diminished = diminished,
-        // save the campaign to the disk + update the flow.
+                )
-        store.save(
+                // save the campaign to the disk + update the flow.
-            campaign = campaign.copy(npcs = npcs)
+                store.save(
-        )
+                    campaign = campaign.copy(characters = characters)
+                )
+            }
+
+            campaign.npcs.containsKey(characterInstanceId) -> {
+                // fetch all the current campaign character
+                val npcs = campaign.npcs.toMutableMap()
+                // update the corresponding character using the use case.
+                npcs[characterInstanceId] = useCase.updateDiminished(
+                    instance = campaign.npc(id = characterInstanceId),
+                    diminished = diminished,
+                )
+                // save the campaign to the disk + update the flow.
+                store.save(
+                    campaign = campaign.copy(npcs = npcs)
+                )
+            }
+        }
+
     }
 }

server/src/main/kotlin/com/pixelized/server/lwa/model/campaign/CampaignStore.kt

@@ -10,7 +10,6 @@ import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.launch
-import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.Json
 import java.io.File
 
@@ -18,7 +17,6 @@ class CampaignStore(
     private val factory: CampaignJsonFactory,
     private val json: Json,
 ) {
-
     private val flow = MutableStateFlow(value = Campaign.EMPTY)
 
     init {

server/src/main/kotlin/com/pixelized/server/lwa/server/Engine.kt

@@ -3,11 +3,12 @@ package com.pixelized.server.lwa.server
 import com.pixelized.server.lwa.model.alteration.AlterationService
 import com.pixelized.server.lwa.model.campaign.CampaignService
 import com.pixelized.server.lwa.model.character.CharacterSheetService
+import com.pixelized.shared.lwa.model.campaign.Campaign
 import com.pixelized.shared.lwa.model.campaign.CampaignJsonFactory
 import com.pixelized.shared.lwa.protocol.websocket.Message
+import com.pixelized.shared.lwa.protocol.websocket.payload.CampaignMessage
 import com.pixelized.shared.lwa.protocol.websocket.payload.RestSynchronisation
 import com.pixelized.shared.lwa.protocol.websocket.payload.RollMessage
-import com.pixelized.shared.lwa.protocol.websocket.payload.UpdatePlayerCharacteristicMessage
 import com.pixelized.shared.lwa.protocol.websocket.payload.UpdateSkillUsageMessage
 import kotlinx.coroutines.flow.MutableSharedFlow
 
@@ -24,12 +25,23 @@ class Engine(
 
             is RollMessage -> Unit // Nothing to do here.
 
-            is UpdatePlayerCharacteristicMessage -> {
+            is CampaignMessage -> {
-                campaignService.updateCharacterCharacteristic(
+                val instanceId = Campaign.CharacterInstance.Id(
-                    characterInstanceId = campaignJsonFactory.convertFromV1(characterInstanceIdJson = data.characterInstanceId),
+                    characterSheetId = data.characterSheetId,
-                    characteristic = campaignJsonFactory.convertFromV1(characteristicJson = data.characteristic),
+                    instanceId = data.instanceId,
-                    value = data.value,
                 )
+                when (data) {
+                    is CampaignMessage.UpdateCharacteristic -> campaignService.updateCharacteristic(
+                        characterInstanceId = instanceId,
+                        characteristic = campaignJsonFactory.convertFromV1(characteristicJson = data.characteristic),
+                        value = data.value,
+                    )
+
+                    is CampaignMessage.UpdateDiminished -> campaignService.updateDiminished(
+                        characterInstanceId = instanceId,
+                        diminished = data.diminished,
+                    )
+                }
             }
 
             is UpdateSkillUsageMessage -> characterService.updateCharacterSkillUsage(

shared/src/commonMain/kotlin/com/pixelized/shared/lwa/model/campaign/Campaign.kt

@@ -6,6 +6,7 @@ data class Campaign(
 ) {
     data class CharacterInstance(
         val characteristic: Map<Characteristic, Int>,
+        val diminished: Int,
     ) {
         data class Id(
             val characterSheetId: String,
@@ -16,6 +17,13 @@ data class Campaign(
             Damage,
             Power,
         }
+
+        companion object {
+            fun empty() = CharacterInstance(
+                characteristic = emptyMap(),
+                diminished = 0,
+            )
+        }
     }
 
     companion object {
@@ -27,15 +35,11 @@ data class Campaign(
 }
 
 fun Campaign.character(id: Campaign.CharacterInstance.Id): Campaign.CharacterInstance {
-    return characters[id] ?: Campaign.CharacterInstance(
+    return characters[id] ?: Campaign.CharacterInstance.empty()
-        characteristic = emptyMap(),
-    )
 }
 
 fun Campaign.npc(id: Campaign.CharacterInstance.Id): Campaign.CharacterInstance {
-    return npcs[id] ?: Campaign.CharacterInstance(
+    return npcs[id] ?: Campaign.CharacterInstance.empty()
-        characteristic = emptyMap(),
-    )
 }
 
 val Campaign.CharacterInstance.level

shared/src/commonMain/kotlin/com/pixelized/shared/lwa/model/campaign/CampaignJsonFactory.kt

@@ -47,6 +47,7 @@ class CampaignJsonFactory {
             characteristic = characterInstanceJson.characteristic
                 .map { char -> convertFromV1(characteristicJson = char.key) to char.value }
                 .toMap(),
+            diminished = characterInstanceJson.diminished ?: 0,
         )
     }
 
@@ -85,6 +86,7 @@ class CampaignJsonFactory {
             characteristic = data.characteristic
                 .map { char -> convertToJson(characteristic = char.key) to char.value }
                 .toMap(),
+            diminished = data.diminished,
         )
     }
 

shared/src/commonMain/kotlin/com/pixelized/shared/lwa/model/campaign/CampaignJsonV1.kt

@@ -11,6 +11,7 @@ data class CampaignJsonV1(
     @Serializable
     data class CharacterInstanceJson(
         val characteristic: Map<Characteristic, Int>,
+        val diminished: Int?,
     ) {
         enum class Characteristic {
             Damage,

shared/src/commonMain/kotlin/com/pixelized/shared/lwa/protocol/websocket/payload/CampaignMessage.kt

@@ -0,0 +1,25 @@
+package com.pixelized.shared.lwa.protocol.websocket.payload
+
+import com.pixelized.shared.lwa.model.campaign.CampaignJsonV1
+import kotlinx.serialization.Serializable
+
+@Serializable
+sealed interface CampaignMessage : MessagePayload {
+    val characterSheetId: String
+    val instanceId: Int
+
+    @Serializable
+    data class UpdateCharacteristic(
+        override val characterSheetId: String,
+        override val instanceId: Int,
+        val characteristic: CampaignJsonV1.CharacterInstanceJson.Characteristic,
+        val value: Int,
+    ) : CampaignMessage
+
+    @Serializable
+    data class UpdateDiminished(
+        override val characterSheetId: String,
+        override val instanceId: Int,
+        val diminished: Int,
+    ) : CampaignMessage
+}

shared/src/commonMain/kotlin/com/pixelized/shared/lwa/protocol/websocket/payload/UpdatePlayerCharacteristicMessage.kt

@@ -1,11 +0,0 @@
-package com.pixelized.shared.lwa.protocol.websocket.payload
-
-import com.pixelized.shared.lwa.model.campaign.CampaignJsonV1
-import kotlinx.serialization.Serializable
-
-@Serializable
-data class UpdatePlayerCharacteristicMessage(
-    val characterInstanceId: String,
-    val characteristic: CampaignJsonV1.CharacterInstanceJson.Characteristic,
-    val value: Int,
-) : MessagePayload

shared/src/commonMain/kotlin/com/pixelized/shared/lwa/usecase/CampaignUseCase.kt

@@ -5,14 +5,23 @@ import com.pixelized.shared.lwa.model.campaign.Campaign
 class CampaignUseCase {
 
     fun updateCharacteristic(
-        character: Campaign.CharacterInstance,
+        instance: Campaign.CharacterInstance,
         characteristic: Campaign.CharacterInstance.Characteristic,
         value: Int,
     ): Campaign.CharacterInstance {
-        return character.copy(
+        return instance.copy(
-            characteristic = character.characteristic.toMutableMap().also {
+            characteristic = instance.characteristic.toMutableMap().also {
                 it[characteristic] = value
             }
         )
     }
+
+    fun updateDiminished(
+        instance: Campaign.CharacterInstance,
+        diminished: Int,
+    ): Campaign.CharacterInstance {
+        return instance.copy(
+            diminished = diminished,
+        )
+    }
 }

shared/src/commonMain/kotlin/com/pixelized/shared/lwa/usecase/ExpressionUseCase.kt

@@ -24,6 +24,7 @@ class ExpressionUseCase(
     fun computeSkillValue(
         sheet: CharacterSheet,
         alterations: Map<String, List<FieldAlteration>>,
+        diminished: Int,
         skill: CharacterSheet.Skill,
     ): Int {
         val context = Context(
@@ -51,7 +52,7 @@ class ExpressionUseCase(
             context.evaluate(it.expression)
         } ?: 0
 
-        return max(base + bonus + level + alteration, 0)
+        return max(base + bonus + level + alteration - diminished, 0)
     }
 
     fun computeRoll(