feat(session): add configurable TTL-based session expiry

src/main/kotlin/com/github/codeplangui/ChatService.kt

@@ -667,6 +667,8 @@ $selection
         if (session.getMessages().any { it.role != MessageRole.SYSTEM }) {
             return
         }
+        val ttlDays = PluginSettings.getInstance().state.sessionTtlDays
+        sessionStore.evictExpiredSessions(ttlDays)
         val data = sessionStore.loadSession() ?: return
         session = ChatSession(data.threadId)
         data.messages.forEach { session.add(it) }

src/main/kotlin/com/github/codeplangui/settings/PluginSettings.kt

@@ -32,7 +32,8 @@ data class SettingsState(
     var memoryText: String = "",
     var commandExecutionEnabled: Boolean = true,
     var commandWhitelist: MutableList<String> = ShellPlatform.current().defaultWhitelist().toMutableList(),
-    var commandTimeoutSeconds: Int = 30
+    var commandTimeoutSeconds: Int = 30,
+    var sessionTtlDays: Int = 30
 )
 
 @State(

src/main/kotlin/com/github/codeplangui/settings/PluginSettingsConfigurable.kt

@@ -60,6 +60,7 @@ class PluginSettingsConfigurable : Configurable {
     private lateinit var commandTimeoutSpinner: JSpinner
     private lateinit var commandWhitelistModel: DefaultListModel<String>
     private lateinit var commandWhitelistList: JList<String>
+    private lateinit var sessionTtlDaysSpinner: JSpinner
     private val client = OkHttpSseClient()
     private val pendingApiKeyUpdates = linkedMapOf<String, String?>()
 
@@ -208,6 +209,8 @@ class PluginSettingsConfigurable : Configurable {
             wrapStyleWord = true
         }
 
+        sessionTtlDaysSpinner = JSpinner(SpinnerNumberModel(settings.sessionTtlDays, 1, 365, 1))
+
         val chatCommitPanel = FormBuilder.createFormBuilder()
             .addLabeledComponent("Temperature:", temperatureSpinner)
             .addLabeledComponent("Max Tokens:", maxTokensSpinner)
@@ -240,6 +243,10 @@ class PluginSettingsConfigurable : Configurable {
                 JBLabel("AI 记忆（注入所有对话的系统提示词）:"),
                 JScrollPane(memoryTextArea)
             )
+            .addLabeledComponent(
+                "Session 过期天数 (0 = 永不过期):",
+                sessionTtlDaysSpinner
+            )
             .panel
 
         val execSettings = SettingsFormState.fromSettingsState(PluginSettings.getInstance().getState())
@@ -345,6 +352,7 @@ class PluginSettingsConfigurable : Configurable {
         commitMaxFilesSpinner.value = settings.commitMaxFiles
         commitDiffLineLimitSpinner.value = settings.commitDiffLineLimit
         memoryTextArea.text = settings.memoryText
+        sessionTtlDaysSpinner.value = settings.sessionTtlDays
         val execState = SettingsFormState.fromSettingsState(PluginSettings.getInstance().getState())
         commandExecutionCheckbox.isSelected = execState.commandExecutionEnabled
         commandTimeoutSpinner.value = execState.commandTimeoutSeconds
@@ -375,6 +383,7 @@ class PluginSettingsConfigurable : Configurable {
             commandWhitelistModel.getElementAt(it)
         }.toMutableList(),
         commandTimeoutSeconds = (commandTimeoutSpinner.value as Number).toInt(),
+        sessionTtlDays = (sessionTtlDaysSpinner.value as Number).toInt(),
     )
 
     private fun selectedProviderId(): String? =

src/main/kotlin/com/github/codeplangui/settings/SettingsFormState.kt

@@ -17,7 +17,8 @@ data class SettingsFormState(
     var memoryText: String = "",
     var commandExecutionEnabled: Boolean = true,
     var commandWhitelist: MutableList<String> = ShellPlatform.current().defaultWhitelist().toMutableList(),
-    var commandTimeoutSeconds: Int = 30
+    var commandTimeoutSeconds: Int = 30,
+    var sessionTtlDays: Int = 30
 ) {
     fun toSettingsState(): SettingsState = SettingsState(
         providers = providers.toMutableList(),
@@ -35,6 +36,7 @@ data class SettingsFormState(
         commandExecutionEnabled = commandExecutionEnabled,
         commandWhitelist = commandWhitelist.toMutableList(),
         commandTimeoutSeconds = commandTimeoutSeconds,
+        sessionTtlDays = sessionTtlDays,
     )
 
     companion object {
@@ -54,6 +56,7 @@ data class SettingsFormState(
             commandExecutionEnabled = state.commandExecutionEnabled,
             commandWhitelist = state.commandWhitelist.toMutableList(),
             commandTimeoutSeconds = state.commandTimeoutSeconds,
+            sessionTtlDays = state.sessionTtlDays,
         )
     }
 }

src/main/kotlin/com/github/codeplangui/storage/SessionStore.kt

@@ -10,11 +10,14 @@ import java.nio.file.Files
 import java.nio.file.Path
 import java.nio.file.StandardCopyOption
 import java.security.MessageDigest
+import java.time.Instant
+import java.time.temporal.ChronoUnit
 
 @Serializable
 data class SessionData(
     val threadId: String,
-    val messages: List<Message>
+    val messages: List<Message>,
+    val lastAccessedAt: Long = System.currentTimeMillis()
 )
 
 class SessionStore(private val projectId: String) {
@@ -41,7 +44,7 @@ class SessionStore(private val projectId: String) {
 
     fun saveSession(threadId: String, messages: List<Message>) {
         try {
-            val data = SessionData(threadId, messages)
+            val data = SessionData(threadId, messages, lastAccessedAt = System.currentTimeMillis())
             val content = json.encodeToString(data)
             Files.writeString(tempFile, content)
             try {
@@ -66,6 +69,38 @@ class SessionStore(private val projectId: String) {
         }
     }
 
+    /**
+     * Evict sessions that haven't been accessed within [ttlDays] days.
+     * Scans all project session directories under the sessions root.
+     */
+    fun evictExpiredSessions(ttlDays: Int) {
+        if (ttlDays <= 0) return
+        try {
+            val sessionsRoot = dataDir.parent
+            if (!Files.isDirectory(sessionsRoot)) return
+            val cutoff = Instant.now().minus(ttlDays.toLong(), ChronoUnit.DAYS)
+            Files.list(sessionsRoot).use { dirs ->
+                dirs.filter { Files.isDirectory(it) }.forEach { projectDir ->
+                    val file = projectDir.resolve("session.json")
+                    if (!Files.exists(file)) return@forEach
+                    try {
+                        val content = Files.readString(file)
+                        val data = json.decodeFromString<SessionData>(content)
+                        val lastAccess = Instant.ofEpochMilli(data.lastAccessedAt)
+                        if (lastAccess.isBefore(cutoff)) {
+                            Files.deleteIfExists(file)
+                            logger.warn("Evicted expired session: $projectDir (last accessed $lastAccess)")
+                        }
+                    } catch (e: Exception) {
+                        logger.warn("Failed to check session expiry for $projectDir", e)
+                    }
+                }
+            }
+        } catch (e: Exception) {
+            logger.warn("Failed to evict expired sessions", e)
+        }
+    }
+
     fun clearSession() {
         try {
             Files.deleteIfExists(sessionFile)