ellie: point preservation, stale-stream guard, block-headers, keybinding polish, and doc screenshot

ellie.el:
- Preserve tree selection and cursor across tree rerenders.
- Keep chat cursor stationary; only update when already at end.
- Guard chat-filter against stale output from replaced ollie-9p read processes.
- Render [[[name]]] markers as bold underlined block headers; suppress [[[end]]].
- Refresh session/idx and start timer on startup so tree displays immediately.
- Fix Active/Inactive header tuple layout (was missing 'nil' slot).
- Bind TAB for tree expand/collapse, C-c C-SPC and C-c C-p for prompt input,
  SPC in chat for prompt, q in chat for quit (stops stream + buries buffer).
- RET on an agent now opens the chat buffer.
- Prompt input window selects and focuses itself after opening.

doc/ellie.md:
- Embed ellie screenshot (img/ellie.png) centered at 75% width above Session tree.

contrib/elisp/ellie.el

@@ -394,7 +394,7 @@ Prompts for agent profile and other options."
       (setq ellie--tree-expanded '("active"))
       (dolist (s sessions)
         (push (nth 2 s) ellie--tree-expanded)))
-    (push (list 'header "active" "Active") result)
+    (push (list 'header "active" nil "Active") result)
     (when (and active (member "active" ellie--tree-expanded))
       (dolist (s active)
         (let ((name (nth 1 s)) (id (nth 2 s)) (agents (nth 3 s)))
@@ -409,7 +409,7 @@ Prompts for agent profile and other options."
                       result)))))))
     ;; Inactive header
     (when inactive
-      (push (list 'header "inactive" "Inactive") result)
+      (push (list 'header "inactive" nil "Inactive") result)
       (when (member "inactive" ellie--tree-expanded)
         (dolist (s inactive)
           (let ((name (nth 1 s)) (id (nth 2 s)) (agents (nth 3 s)))
@@ -486,7 +486,7 @@ Prompts for agent profile and other options."
       (setq ellie--session-id parent
             ellie--agent-id key)
       (ellie--persist-session parent)
-      (message "Agent: %s / %s" parent key)))))
+      (ellie-tree-chat)))))
 
 (defun ellie-tree-chat ()
   "Open chat buffer for the selected session/agent."
@@ -555,15 +555,35 @@ Prompts for agent profile and other options."
 (defvar ellie--chat-stream nil
   "Process object for the chat stream, or nil.")
 
-(defun ellie--chat-filter (_proc output)
+(defun ellie--render-chat-output (output)
+  "Render block markers in OUTPUT as block headers.
+Suppress `[[[end]]]` markers."
+  (let ((start 0)
+        rendered)
+    (while (string-match "\\[\\[\\[\\([^]]+\\)\\]\\]\\]" output start)
+      (push (substring output start (match-beginning 0)) rendered)
+      (let ((name (match-string 1 output)))
+        (unless (string= name "end")
+          (push (propertize (concat name "\n")
+                            'face '(:weight bold :underline t))
+                rendered)))
+      (setq start (match-end 0)))
+    (apply #'concat (nreverse (cons (substring output start) rendered)))))
+
+(defun ellie--chat-filter (proc output)
   "Filter function for the chat stream process.
-Inserts OUTPUT into the chat buffer as it arrives."
-  (when (buffer-live-p (get-buffer ellie--buf))
+Ignore output from a stream that has already been replaced."
+  (when (and (eq proc ellie--chat-stream)
+             (buffer-live-p (get-buffer ellie--buf)))
     (with-current-buffer ellie--buf
       (let ((inhibit-read-only t)
-            (at-end (= (point) (point-max))))
-        (insert output)
-        (ansi-color-apply-on-region (point-marker) (point))
+            (at-end (= (point) (point-max)))
+            (start (copy-marker (point-max) t)))
+        (save-excursion
+          (goto-char (point-max))
+          (insert (ellie--render-chat-output output))
+          (ansi-color-apply-on-region start (point)))
+        (set-marker start nil)
         (font-lock-ensure)
         (when at-end (goto-char (point-max))))
       (force-mode-line-update))))
@@ -614,9 +634,13 @@ QUEUED non-nil means the prompt will be enqueued, not submitted immediately."
       (erase-buffer)
       (ellie-input-mode)
       (setq ellie--input-queued queued))
-    (display-buffer buf
-                    `(display-buffer-below-selected
-                      (window-height . ,ellie-input-window-height)))))
+    (let ((window (display-buffer buf
+                                  `(display-buffer-below-selected
+                                    (window-height . ,ellie-input-window-height)))))
+      (when (window-live-p window)
+        (select-window window)
+        (with-current-buffer buf
+          (goto-char (point-max)))))))
 
 (defun ellie-input-submit ()
   "Submit the contents of the input buffer as a prompt."
@@ -645,6 +669,7 @@ QUEUED non-nil means the prompt will be enqueued, not submitted immediately."
 (defvar ellie-mode-map
   (let ((m (make-sparse-keymap)))
     (define-key m (kbd "RET")     #'ellie-send-input)
+    (define-key m (kbd "SPC")     #'ellie-send-input)
     (define-key m (kbd "C-c C-q") #'ellie-queue-input)
     (define-key m (kbd "C-c C-c") #'ellie-stop)
     (define-key m (kbd "C-c C-k") #'ellie-kill-session)
@@ -653,7 +678,7 @@ QUEUED non-nil means the prompt will be enqueued, not submitted immediately."
     (define-key m (kbd "C-c C-p") #'ellie-show-system-prompt)
     (define-key m (kbd "n")       #'ellie-new-and-open)
     (define-key m (kbd "g")       #'ellie-refresh-chat)
-    (define-key m (kbd "q")       #'ellie-tree)
+    (define-key m (kbd "q")       #'ellie-quit-chat)
     m)
   "Keymap for `ellie-mode'.")
 
@@ -667,6 +692,12 @@ QUEUED non-nil means the prompt will be enqueued, not submitted immediately."
   (interactive)
   (ellie--open-input t))
 
+(defun ellie-quit-chat ()
+  "Stop the chat stream and bury the chat buffer."
+  (interactive)
+  (ellie--stop-watching)
+  (bury-buffer (get-buffer ellie--buf)))
+
 (defun ellie-refresh-chat ()
   "Restart the chat stream."
   (interactive)
@@ -740,13 +771,15 @@ QUEUED non-nil means the prompt will be enqueued, not submitted immediately."
         (message "Attached to session %s" (car last)))
     (setq ellie--session-id nil
           ellie--agent-id nil))
-  (ellie--tree-render))
+  (ellie--tree-render)
+  (run-at-time 0.5 nil #'ellie-tree-refresh))
 
 ;;;###autoload
 (defun ellie-tree ()
   "Open the session tree buffer."
   (interactive)
-  (ellie--tree-render))
+  (ellie--tree-render)
+  (run-at-time 0.5 nil #'ellie-tree-refresh))
 
 (defun ellie-new-and-open ()
   "Create a new session and open the chat buffer."

doc/ellie.md

@@ -44,6 +44,10 @@ M-x ellie
 Opens the session tree (`*ellie-sessions*`), attached to the last-known
 session for your working directory if it still exists.
 
+<p align="center">
+  <img src="img/ellie.png" alt="ellie Emacs interface showing the Ollie session tree and chat window" width="75%">
+</p>
+
 ## Session tree
 
 The tree shows all sessions organized by active/inactive state: