Fix vterm-copy-mode disrupted by anti-flicker timer in Claude Code sessions

ai-code-backends-infra.el

@@ -35,6 +35,9 @@
 (defvar vterm-shell)
 (defvar vterm-environment)
 (defvar vterm-kill-buffer-on-exit)
+(defvar vterm-copy-mode)
+(defvar eat-terminal)
+(defvar eat--semi-char-mode)
 
 ;;; Customization
 
@@ -145,6 +148,12 @@ being sent for the response completion.")
 (defvar-local ai-code-backends-infra--multiline-input-sequence nil
   "Terminal sequence sent for multiline input in the current session buffer.")
 
+(defvar-local ai-code-backends-infra--terminal-active-cursor-type nil
+  "Cursor type to restore when returning to terminal interaction mode.")
+
+(defvar-local ai-code-backends-infra--navigation-cursor-active nil
+  "Non-nil when Emacs temporarily owns the cursor for output navigation.")
+
 (defvar ai-code-cli-args-history nil
   "History list for CLI args prompts.")
 
@@ -240,7 +249,9 @@ The timer is reset only after meaningful output is observed."
 (defun ai-code-backends-infra--vterm-smart-renderer (orig-fun process input)
   "Smart rendering filter for optimized vterm display updates.
 Activity tracking for notifications is handled separately by
-`ai-code-backends-infra--vterm-notification-tracker'."
+`ai-code-backends-infra--vterm-notification-tracker'.
+Deferred rendering is suspended while `vterm-copy-mode' is active so that
+scrolling and copying are not disrupted by timer-driven redraws."
   (if (or (not ai-code-backends-infra-vterm-anti-flicker)
           (not (ai-code-backends-infra--session-buffer-p (process-buffer process))))
       (funcall orig-fun process input)
@@ -253,7 +264,8 @@ Activity tracking for notifications is handled separately by
              (escape-density (if (> input-length 0) (/ (float escape-count) input-length) 0)))
         (if (or complex-redraw-detected
                 (and (> escape-density 0.3) (>= clear-count 2))
-                ai-code-backends-infra--vterm-render-queue)
+                ai-code-backends-infra--vterm-render-queue
+                (bound-and-true-p vterm-copy-mode))
             (progn
               (setq ai-code-backends-infra--vterm-render-queue
                     (concat ai-code-backends-infra--vterm-render-queue input))
@@ -264,15 +276,29 @@ Activity tracking for notifications is handled separately by
                                  (lambda (buf)
                                    (when (buffer-live-p buf)
                                      (with-current-buffer buf
-                                       (when ai-code-backends-infra--vterm-render-queue
+                                       ;; Clear timer reference regardless of whether we render.
+                                       (setq ai-code-backends-infra--vterm-render-timer nil)
+                                       (when (and ai-code-backends-infra--vterm-render-queue
+                                                  (not (bound-and-true-p vterm-copy-mode)))
                                          (let ((inhibit-redisplay t)
                                                (data ai-code-backends-infra--vterm-render-queue))
-                                           (setq ai-code-backends-infra--vterm-render-queue nil
-                                                 ai-code-backends-infra--vterm-render-timer nil)
+                                           (setq ai-code-backends-infra--vterm-render-queue nil)
                                            (funcall orig-fun (get-buffer-process buf) data))))))
                                  (current-buffer))))
           (funcall orig-fun process input))))))
 
+(defun ai-code-backends-infra--vterm-flush-on-copy-mode-exit ()
+  "Flush any pending render queue when exiting `vterm-copy-mode'.
+Added buffer-locally to `vterm-copy-mode-hook' so that terminal output
+queued while copy mode was active is rendered immediately when the user
+returns to normal terminal interaction."
+  (unless (bound-and-true-p vterm-copy-mode)
+    (when ai-code-backends-infra--vterm-render-queue
+      (when-let ((proc (get-buffer-process (current-buffer))))
+        (let ((data ai-code-backends-infra--vterm-render-queue))
+          (setq ai-code-backends-infra--vterm-render-queue nil)
+          (vterm--filter proc data))))))
+
 (defun ai-code-backends-infra--configure-vterm-buffer ()
   "Configure vterm for enhanced performance."
   (setq-local vterm-scroll-to-bottom-on-output nil)
@@ -289,6 +315,11 @@ Activity tracking for notifications is handled separately by
     (set-process-query-on-exit-flag proc nil)
     (when (fboundp 'process-put)
       (process-put proc 'read-output-max 4096)))
+  ;; Flush queued render output when the user exits vterm-copy-mode.
+  (add-hook 'vterm-copy-mode-hook
+            #'ai-code-backends-infra--vterm-flush-on-copy-mode-exit nil t)
+  ;; Hand cursor ownership to Emacs while browsing frozen terminal output.
+  (ai-code-backends-infra--install-navigation-cursor-sync)
   ;; Install vterm filter advices globally (only once)
   (unless ai-code-backends-infra--vterm-advices-installed
     ;; Always install notification tracker for session buffers
@@ -320,6 +351,36 @@ Activity tracking for notifications is handled separately by
   (or ai-code-backends-infra--session-terminal-backend
       ai-code-backends-infra-terminal-backend))
 
+(defun ai-code-backends-infra--terminal-navigation-mode-p ()
+  "Return non-nil when the current terminal buffer is in navigation mode."
+  (pcase (ai-code-backends-infra--current-terminal-backend)
+    ('vterm (bound-and-true-p vterm-copy-mode))
+    ('eat (and (bound-and-true-p eat-terminal)
+               (or buffer-read-only
+                   (not (bound-and-true-p eat--semi-char-mode)))))
+    (_ nil)))
+
+(defun ai-code-backends-infra--sync-terminal-cursor ()
+  "Hand cursor ownership between the terminal and Emacs navigation modes."
+  (if (ai-code-backends-infra--terminal-navigation-mode-p)
+      (unless ai-code-backends-infra--navigation-cursor-active
+        (setq ai-code-backends-infra--terminal-active-cursor-type cursor-type
+              ai-code-backends-infra--navigation-cursor-active t
+              cursor-type t))
+    (when ai-code-backends-infra--navigation-cursor-active
+      (setq cursor-type ai-code-backends-infra--terminal-active-cursor-type
+            ai-code-backends-infra--navigation-cursor-active nil))))
+
+(defun ai-code-backends-infra--install-navigation-cursor-sync ()
+  "Install buffer-local hooks for cursor handoff in terminal navigation modes."
+  (pcase (ai-code-backends-infra--current-terminal-backend)
+    ('vterm
+     (add-hook 'vterm-copy-mode-hook
+               #'ai-code-backends-infra--sync-terminal-cursor nil t))
+    ('eat
+     (add-hook 'post-command-hook
+               #'ai-code-backends-infra--sync-terminal-cursor nil t))))
+
 (defun ai-code-backends-infra--terminal-dispatch (vterm-fn eat-fn)
   "Run VTERM-FN or EAT-FN based on selected terminal backend."
   (pcase (ai-code-backends-infra--current-terminal-backend)
@@ -925,6 +986,7 @@ ENV-VARS is a list of environment variables."
             (local-set-key (kbd "@") #'ai-code--session-handle-at-input))
           (when (fboundp 'ai-code--session-handle-hash-input)
             (local-set-key (kbd "#") #'ai-code--session-handle-hash-input))
+          (ai-code-backends-infra--install-navigation-cursor-sync)
           (setq-local process-environment (append env-vars process-environment))
           (eat-exec buffer buffer-name program nil args)
           ;; Add process filter to track activity for notifications