fix: ensure chat log lines are newline-terminated

assistant events are streamed without trailing newlines, causing
line-buffered 9P reads to lag one turn behind. Close the assistant
block with \n on role transitions and after Submit returns. Set
ChatOffset at EOF before the user event so offset spans the full
exchange. Remove 500-char truncation of tool call args in FormatEvent.

pkg/store/batch.go

@@ -373,13 +373,24 @@ func (s *BatchStore) executeJob(ctx context.Context, job *batchJob) (string, err
 				assistantStarted = true
 			}
 		case "user", "call", "tool":
-			assistantStarted = false
+			if assistantStarted {
+				job.appendLog([]byte("\n"))
+				assistantStarted = false
+			}
 		case "error":
 			errBuf.WriteString(ev.Content)
 		}
 		job.appendLog(FormatEvent(ev))
 	})
 
+	// Ensure log ends with newline (assistant content has no trailing \n).
+	job.mu.Lock()
+	if len(job.log) > 0 && job.log[len(job.log)-1] != '\n' {
+		job.log = append(job.log, '\n')
+		job.logVers++
+	}
+	job.mu.Unlock()
+
 	usage := core.Usage()
 	ctxsz := core.CtxSz()
 
@@ -620,9 +631,6 @@ func FormatEvent(ev agent.Event) []byte {
 		return []byte(ev.Content)
 	case "call":
 		args := squashWhitespace(ev.Content)
-		if len(args) > 500 {
-			args = args[:500] + "..."
-		}
 		return []byte("-> " + ev.Name + "(" + args + ")\n")
 	case "tool":
 		return []byte(strings.TrimRight(ev.Content, "\n") + "\n")

pkg/store/session.go

@@ -52,6 +52,16 @@ func (sess *Session) AppendLog(data []byte) {
 	sess.mu.Unlock()
 }
 
+// EnsureTrailingNewline appends a newline if the log doesn't already end with one.
+func (sess *Session) EnsureTrailingNewline() {
+	sess.mu.Lock()
+	if len(sess.log) > 0 && sess.log[len(sess.log)-1] != '\n' {
+		sess.log = append(sess.log, '\n')
+		sess.logVers++
+	}
+	sess.mu.Unlock()
+}
+
 // LogInfo returns the current log length and version atomically.
 func (sess *Session) LogInfo() (length int, vers uint32) {
 	sess.mu.RLock()

pkg/store/sessionfile.go

@@ -159,7 +159,9 @@ func (s *SessionFileStore) writeFile(name string, data []byte) error {
 	case "chat":
 		return s.saveTranscript([]byte(input))
 	case "prompt":
-		s.sess.Core.Submit(s.sess.Ctx, input, s.makePublish())
+		pub := s.makePublish()
+		s.sess.Core.Submit(s.sess.Ctx, input, pub)
+		s.sess.EnsureTrailingNewline()
 	case "fifo.in":
 		s.sess.Core.Queue(input)
 	case "ctl":
@@ -352,21 +354,29 @@ func (s *SessionFileStore) currentWaitValue(name string) string {
 func (s *SessionFileStore) makePublish() func(agent.Event) {
 	assistantStarted := false
 	return func(ev agent.Event) {
-		switch ev.Role {
-		case "user", "call", "tool":
-			assistantStarted = false
-		case "assistant":
-			if !assistantStarted {
-				s.sess.AppendLog([]byte("assistant: "))
-				assistantStarted = true
-			}
-		}
-		s.sess.AppendLog(FormatEvent(ev))
 		if ev.Role == "user" {
+			if assistantStarted {
+				s.sess.AppendLog([]byte("\n"))
+				assistantStarted = false
+			}
 			s.sess.mu.Lock()
 			s.sess.ChatOffset = len(s.sess.log)
 			s.sess.mu.Unlock()
+		} else {
+			switch ev.Role {
+			case "call", "tool":
+				if assistantStarted {
+					s.sess.AppendLog([]byte("\n"))
+					assistantStarted = false
+				}
+			case "assistant":
+				if !assistantStarted {
+					s.sess.AppendLog([]byte("assistant: "))
+					assistantStarted = true
+				}
+			}
 		}
+		s.sess.AppendLog(FormatEvent(ev))
 	}
 }