fix(#686): implement robust history pagination (#687)

* fix(#686): implement robust history pagination

Honor server-returned offset, degrade gracefully on older servers, and parse JSON tool results.

* fix(ci): repair unit-test compilation and pagination test mocks

- Remove trailing blank line in SessionMessagesResponse.kt (ktlint)
- Replace unresolved io.mockk.eq/coAnswers usage in ChatViewModelTest with
  an ordered-call counter inside coAnswers, which compiles and runs on
  MockK 1.14.11 (eq is a matcher-scope member, not a top-level import)
- Align HermesApiServiceMockWebServerTest with the PR's JsonElement content
  model (contentText) and the new include_compacted=true default query param

All unit tests pass locally with the ByteBuddy agent preload.

---------

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/data/model/SessionMessagesResponse.kt

@@ -1,4 +1,5 @@
 package com.m57.hermescontrol.data.model
+
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.JsonElement
 import kotlinx.serialization.json.JsonPrimitive
@@ -6,15 +7,25 @@ import kotlinx.serialization.json.JsonPrimitive
 @Serializable
 data class SessionMessagesResponse(
     val messages: List<SessionMessage>,
+    val offset: Int? = null,
+    val total: Int? = null,
 )
 
 @Serializable
 data class SessionMessage(
     val role: String? = null,
-    val content: String? = null,
+    val content: JsonElement? = null,
     val timestamp: JsonElement? = null,
     val type: String? = null,
 ) {
     val timestampText: String?
         get() = (timestamp as? JsonPrimitive)?.content
+
+    val contentText: String
+        get() =
+            when (content) {
+                is JsonPrimitive -> content.content
+                null -> ""
+                else -> content.toString()
+            }
 }

app/src/main/java/com/m57/hermescontrol/data/remote/HermesApiService.kt

@@ -143,6 +143,7 @@ interface HermesApiService {
         @Path("id", encoded = true) sessionId: String,
         @Query("limit") limit: Int? = null,
         @Query("offset") offset: Int = 0,
+        @Query("include_compacted") includeCompacted: Boolean? = true,
     ): Response<SessionMessagesResponse>
 
     @GET("api/sessions/stats")

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatViewModel.kt

@@ -1408,8 +1408,9 @@ class ChatViewModel(
             val result = fetchMessagePage(sessionId, offset, MESSAGE_PAGE_SIZE)
             when (result) {
                 is NetworkResult.Success -> {
-                    val chatMessages = mapServerMessages(sessionId, result.data.messages.orEmpty(), offset)
-                    loadedMessageOffset = offset
+                    val serverOffset = result.data.offset ?: offset
+                    val chatMessages = mapServerMessages(sessionId, result.data.messages.orEmpty(), serverOffset)
+                    loadedMessageOffset = serverOffset
                     withContext(Dispatchers.IO) {
                         repo.persistMessages(chatMessages, sessionId)
                     }
@@ -1418,7 +1419,7 @@ class ChatViewModel(
                         state.copy(
                             messages = chatMessages,
                             isLoading = false,
-                            hasOlderMessages = offset > 0 && chatMessages.isNotEmpty(),
+                            hasOlderMessages = serverOffset > 0 && chatMessages.isNotEmpty(),
                             isLoadingOlder = false,
                         )
                     }
@@ -1449,15 +1450,16 @@ class ChatViewModel(
         viewModelScope.launch {
             when (val result = fetchMessagePage(sessionId, newOffset, limit)) {
                 is NetworkResult.Success -> {
-                    val older = mapServerMessages(sessionId, result.data.messages.orEmpty(), newOffset)
-                    loadedMessageOffset = newOffset
+                    val returnedOffset = result.data.offset ?: newOffset
+                    val older = mapServerMessages(sessionId, result.data.messages.orEmpty(), returnedOffset)
+                    loadedMessageOffset = returnedOffset
                     withContext(Dispatchers.IO) { repo.persistMessages(older, sessionId) }
                     _uiState.update { current ->
                         if (current.currentSessionId != sessionId) return@update current
                         current.copy(
                             messages = (older + current.messages).distinctBy { it.id },
                             isLoadingOlder = false,
-                            hasOlderMessages = newOffset > 0,
+                            hasOlderMessages = returnedOffset < oldOffset && older.isNotEmpty() && returnedOffset > 0,
                         )
                     }
                 }
@@ -1559,7 +1561,14 @@ class ChatViewModel(
         offset: Int,
         limit: Int,
     ) = withContext(Dispatchers.IO) {
-        safeApiCall { ApiClient.hermesApi.getSessionMessages(sessionId, limit = limit, offset = offset) }
+        safeApiCall {
+            ApiClient.hermesApi.getSessionMessages(
+                sessionId = sessionId,
+                limit = limit,
+                offset = offset,
+                includeCompacted = true,
+            )
+        }
     }
 
     private fun mapServerMessages(
@@ -1585,7 +1594,7 @@ class ChatViewModel(
             ChatMessage(
                 id = "rest-$sessionId-$globalIndex",
                 role = role,
-                content = msg.content.orEmpty(),
+                content = msg.contentText,
                 timestamp = timestamp,
                 isStreaming = false,
             )