9p: replay last 20 messages into chat log on session restore

session/session.go

@@ -814,6 +814,10 @@ func (s *Manager) restoreSession(ps *agent.PersistedSession) error {
 	sessPtr = sess
 	sess.uname = uname
 
+	// Replay tail of persisted messages into the chat log so the GUI
+	// and `chat` file show recent history on restore.
+	replayMessagesToLog(sess, ps.Messages)
+
 	s.mu.Lock()
 	s.sessions[sessID] = sess
 	s.mu.Unlock()
@@ -1138,6 +1142,39 @@ func squashWhitespace(s string) string {
 	return strings.Join(strings.Fields(s), " ")
 }
 
+// replayMessagesToLog renders the tail of a persisted message list into the
+// session's chat log so that restored sessions show recent history.
+func replayMessagesToLog(sess *Session, messages []backend.Message) {
+	const maxReplay = 20
+	start := len(messages) - maxReplay
+	if start < 0 {
+		start = 0
+	}
+	// Skip system messages at the start of the replay window.
+	for start < len(messages) && messages[start].Role == "system" {
+		start++
+	}
+	for _, m := range messages[start:] {
+		switch m.Role {
+		case "system":
+			// skip
+		case "user":
+			sess.AppendLog([]byte("[user]\n" + m.Content + "\n"))
+		case "assistant":
+			sess.AppendLog([]byte("[assistant]\n"))
+			if m.Content != "" {
+				sess.AppendLog([]byte(m.Content + "\n"))
+			}
+			for _, tc := range m.ToolCalls {
+				args := squashWhitespace(string(tc.Arguments))
+				sess.AppendLog([]byte("[call:" + tc.Name + "]\n" + args + "\n"))
+			}
+		case "tool":
+			sess.AppendLog([]byte("[tool]\n" + strings.TrimRight(m.Content, "\n") + "\n"))
+		}
+	}
+}
+
 // --- Code Completion ---
 
 // Complete performs a stateless one-shot code completion via backend.Generate.