feat(chat): rank slash autocomplete by usage (issue #865) (#874)

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

app/src/test/java/com/m57/hermescontrol/ui/chat/ChatInputPolicyTest.kt

@@ -107,4 +107,40 @@ class ChatInputPolicyTest {
         val value = ChatInputPolicy.commandFieldValue("/help")
         assertTrue("cursor must be past the shared /h prefix", value.selection.start > 2)
     }
+
+    // ── Slash suggestion ranking (issue #865) ───────────────────────────────
+
+    @Test
+    fun sortSlashSuggestions_mostUsedFirst_tiesKeepCatalogOrder() {
+        val commands = listOf("/help", "/model", "/new", "/stop")
+        val usage = mapOf("/stop" to 5, "/model" to 2)
+
+        assertEquals(
+            "most-used must surface first; equal counts keep catalog order",
+            listOf("/stop", "/model", "/help", "/new"),
+            ChatInputPolicy.sortSlashSuggestions(commands, usage),
+        )
+    }
+
+    @Test
+    fun sortSlashSuggestions_noUsage_keepsCatalogOrder() {
+        val commands = listOf("/help", "/model", "/new")
+        assertEquals(
+            "no history must fall back to catalog order unchanged",
+            commands,
+            ChatInputPolicy.sortSlashSuggestions(commands, emptyMap()),
+        )
+    }
+
+    @Test
+    fun sortSlashSuggestions_lookupIsCaseInsensitive() {
+        // Stored keys are always lowercase (normalized at dispatch time), but
+        // the lookup lowercases the catalog name so a mismatched case can
+        // never break the ranking.
+        val commands = listOf("/model", "/new")
+        assertEquals(
+            listOf("/model", "/new"),
+            ChatInputPolicy.sortSlashSuggestions(commands, mapOf("/MODEL" to 3)),
+        )
+    }
 }

app/src/test/java/com/m57/hermescontrol/ui/chat/ChatViewModelTest.kt

@@ -22,6 +22,7 @@ import com.m57.hermescontrol.data.ws.JsonRpcError
 import com.m57.hermescontrol.data.ws.WsEvent
 import com.m57.hermescontrol.data.ws.WsMethods
 import com.m57.hermescontrol.ui.chat.fakes.FakeChatPersistenceRepository
+import com.m57.hermescontrol.ui.chat.fakes.FakeSlashUsageStore
 import io.mockk.*
 import io.mockk.coEvery
 import io.mockk.coVerify
@@ -67,6 +68,7 @@ class ChatViewModelTest {
     private val mockSwitchFlow = MutableSharedFlow<String>(extraBufferCapacity = 8)
     private lateinit var app: Application
     private lateinit var fakeRepo: FakeChatPersistenceRepository
+    private lateinit var fakeSlashUsageStore: FakeSlashUsageStore
 
     /** Counter used to generate unique WS request IDs. */
     private var reqCount = 0
@@ -114,6 +116,7 @@ class ChatViewModelTest {
 
         app = mockk(relaxed = true)
         fakeRepo = FakeChatPersistenceRepository()
+        fakeSlashUsageStore = FakeSlashUsageStore()
         ActiveSessionHolder.set(null)
 
         mockConnectionStatus.value = ConnectionStatus.DISCONNECTED
@@ -184,7 +187,7 @@ class ChatViewModelTest {
     private fun createViewModel(startCleanup: Boolean = false): ChatViewModel =
         // Both dispatchers injected — a real ioDispatcher would race the
         // test scheduler (repo writes hop it) and shuffle RPC ordering.
-        ChatViewModel(app, startCleanup, fakeRepo, testDispatcher, testDispatcher)
+        ChatViewModel(app, startCleanup, fakeRepo, fakeSlashUsageStore, testDispatcher, testDispatcher)
 
     /**
      * Create ViewModel, simulate GatewayReady, feed SESSION_CREATE result,
@@ -402,6 +405,47 @@ class ChatViewModelTest {
             verify { HermesWsClient.send(WsMethods.SESSION_INTERRUPT, any(), any()) }
         }
 
+    // ── Slash usage ranking (issue #865) ────────────────────────────────────
+
+    @Test
+    fun slashUsage_dispatchIncrementsCountPerCommand() =
+        runTest {
+            val (viewModel, sessionId) = createViewModelWithSession()
+
+            every {
+                HermesWsClient.request(WsMethods.COMMAND_DISPATCH, any(), any())
+            } returns
+                CompletableDeferred(
+                    mapOf("type" to "exec", "output" to "ok"),
+                )
+
+            viewModel.sendMessage("/help")
+            advanceUntilIdle()
+            viewModel.sendMessage("/help")
+            advanceUntilIdle()
+            viewModel.sendMessage("/new")
+            advanceUntilIdle()
+
+            assertEquals(2, viewModel.uiState.value.slashUsageCounts["/help"])
+            assertEquals(1, viewModel.uiState.value.slashUsageCounts["/new"])
+        }
+
+    @Test
+    fun slashUsage_blockedCommand_notCounted() =
+        runTest {
+            val (viewModel, sessionId) = createViewModelWithSession()
+
+            viewModel.sendMessage("/clear")
+            advanceUntilIdle()
+
+            // A blocklisted command can never dispatch — it must not climb
+            // the autocomplete ranking either.
+            assertTrue(viewModel.uiState.value.slashUsageCounts.isEmpty())
+            verify(exactly = 0) {
+                HermesWsClient.request(WsMethods.COMMAND_DISPATCH, any(), any())
+            }
+        }
+
     @Test
     fun testSlashCommand_unknown_showsErrorMessage() =
         runTest {

app/src/test/java/com/m57/hermescontrol/ui/chat/SlashCommandDispatchRpcTest.kt

@@ -9,6 +9,7 @@ import com.m57.hermescontrol.data.ws.HermesWsClient
 import com.m57.hermescontrol.data.ws.WsEvent
 import com.m57.hermescontrol.data.ws.WsMethods
 import com.m57.hermescontrol.ui.chat.fakes.FakeChatPersistenceRepository
+import com.m57.hermescontrol.ui.chat.fakes.FakeSlashUsageStore
 import io.mockk.every
 import io.mockk.mockk
 import io.mockk.mockkObject
@@ -126,7 +127,7 @@ class SlashCommandDispatchRpcTest {
     }
 
     private suspend fun TestScope.createViewModelWithSession(): Pair<ChatViewModel, String> {
-        val vm = ChatViewModel(app, false, fakeRepo, ioDispatcher = testDispatcher)
+        val vm = ChatViewModel(app, false, fakeRepo, FakeSlashUsageStore(), ioDispatcher = testDispatcher)
         advanceUntilIdle()
         mockConnectionStatus.value = ConnectionStatus.CONNECTED
         mockEventsFlow.emit(WsEvent.GatewayReady(null))

app/src/test/java/com/m57/hermescontrol/ui/chat/fakes/FakeSlashUsageStore.kt

@@ -0,0 +1,26 @@
+package com.m57.hermescontrol.ui.chat.fakes
+
+import com.m57.hermescontrol.data.local.SlashUsageStore
+import io.mockk.mockk
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.update
+
+/**
+ * In-memory [SlashUsageStore] for ChatViewModel tests (issue #865).
+ *
+ * Mirrors the real store's semantics: [recordUse] bumps the count and
+ * [counts] emits the current map. The real store needs an Android Context
+ * (DataStore), which unit tests don't have — the relaxed mock is a dummy
+ * the overrides never touch (same pattern as the mocked Application in
+ * ChatViewModelTest).
+ */
+class FakeSlashUsageStore : SlashUsageStore(mockk(relaxed = true)) {
+    private val countsFlow = MutableStateFlow<Map<String, Int>>(emptyMap())
+
+    override fun counts(): Flow<Map<String, Int>> = countsFlow
+
+    override suspend fun recordUse(command: String) {
+        countsFlow.update { it + (command to ((it[command] ?: 0) + 1)) }
+    }
+}