From 9350cb855e687466b350c444fa0013d21632befc Mon Sep 17 00:00:00 2001
From: Amr Gharbeia <amr@gharbeia.net>
Date: Wed, 6 May 2026 17:46:49 -0400
Subject: [PATCH] v0.3.3: left/right cursor movement in input
MIME-Version: 1.0
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Adds :cursor-pos to TUI state. New functions:
- input-insert-char(ch): insert at cursor position, advance cursor
- input-delete-char(): delete char before cursor (standard backspace)

on-key handlers:
- Left arrow: decrement cursor-pos (clamped >= 0)
- Right arrow: increment cursor-pos (clamped <= buffer-len)
- Character input: input-insert-char at cursor position
- Backspace: input-delete-char at cursor position
- Enter: reset cursor-pos to 0

view-input: cursor at visual position matching cursor-pos

Test: (init-state) → (input-insert-char #\h) → (input-insert-char #\i)
→ (setf cursor-pos 1) → (input-insert-char #\X) → 'hXi' at pos 2
---
 lisp/gateway-tui-main.lisp  | 43 +++++++++++++++++++++++--------------
 lisp/gateway-tui-model.lisp | 21 +++++++++++++++++-
 lisp/gateway-tui-view.lisp  |  8 ++++---
 org/gateway-tui-main.org    | 43 +++++++++++++++++++++++--------------
 org/gateway-tui-model.org   | 21 +++++++++++++++++-
 org/gateway-tui-view.org    |  8 ++++---
 6 files changed, 104 insertions(+), 40 deletions(-)

diff --git a/lisp/gateway-tui-main.lisp b/lisp/gateway-tui-main.lisp
index 347fef1..abaf43d 100644
--- a/lisp/gateway-tui-main.lisp
+++ b/lisp/gateway-tui-main.lisp
@@ -94,8 +94,9 @@
                    (setf (st :busy) t)
                    (send-daemon (list :type :event
                                      :payload (list :sensor :user-input :text text)))))
-                (setf (st :input-buffer) nil)
-                (setf (st :dirty) (list t t t))))))
+                 (setf (st :input-buffer) nil)
+                 (setf (st :cursor-pos) 0)
+                 (setf (st :dirty) (list t t t))))))
        ;; Tab — command completion
        ((or (eql ch 9) (eq ch :tab))
         (let ((text (input-string)))
@@ -110,11 +111,21 @@
                 (when (member match '("/eval" "/focus" "/scope") :test #'string=)
                   (push #\Space (st :input-buffer)))
                 (setf (st :dirty) (list nil nil t)))))))
-       ;; Backspace
-       ((or (eq ch :backspace) (eql ch 127) (eql ch 8)
-            (eql ch #\Backspace))
-       (when (st :input-buffer) (pop (st :input-buffer)))
-       (setf (st :dirty) (list nil nil t)))
+        ;; Backspace
+        ((or (eq ch :backspace) (eql ch 127) (eql ch 8)
+             (eql ch #\Backspace))
+        (input-delete-char)
+        (setf (st :dirty) (list nil nil t)))
+       ;; Left arrow
+       ((or (eq ch :left) (eql ch 260))
+        (when (> (or (st :cursor-pos) 0) 0)
+          (decf (st :cursor-pos))
+          (setf (st :dirty) (list nil nil t))))
+       ;; Right arrow
+       ((or (eq ch :right) (eql ch 261))
+        (when (< (or (st :cursor-pos) 0) (length (st :input-buffer)))
+          (incf (st :cursor-pos))
+          (setf (st :dirty) (list nil nil t))))
       ;; Up arrow
       ((or (eq ch :up) (eql ch 259))
        (let* ((h (st :input-history)) (p (st :input-hpos)))
@@ -141,15 +152,15 @@
       ((or (eq ch :npage) (eql ch 338))
        (setf (st :scroll-offset) (max 0 (- (st :scroll-offset) 5)))
        (setf (st :dirty) (list nil t nil)))
-      ;; Printable
-      (t
-       (let ((chr (typecase ch
-                    (character ch)
-                    (integer (code-char ch))
-                    (t nil))))
-         (when (and chr (graphic-char-p chr))
-           (push chr (st :input-buffer))
-           (setf (st :dirty) (list nil nil t))))))))
+       ;; Printable
+       (t
+        (let ((chr (typecase ch
+                     (character ch)
+                     (integer (code-char ch))
+                     (t nil))))
+          (when (and chr (graphic-char-p chr))
+            (input-insert-char chr)
+            (setf (st :dirty) (list nil nil t))))))))
 
 (defun on-daemon-msg (msg)
   (let* ((payload (getf msg :payload))
diff --git a/lisp/gateway-tui-model.lisp b/lisp/gateway-tui-model.lisp
index d45412b..d532012 100644
--- a/lisp/gateway-tui-model.lisp
+++ b/lisp/gateway-tui-model.lisp
@@ -28,7 +28,7 @@
   (setf *state*
         (list :running t :mode :chat :connected nil :stream nil
               :input-buffer nil :input-history nil :input-hpos 0
-              :messages nil :scroll-offset 0 :busy nil
+              :messages nil :scroll-offset 0 :busy nil :cursor-pos 0
               :dirty (list nil nil nil))))
 
 (defun now ()
@@ -39,6 +39,25 @@
 (defun input-string ()
   (coerce (reverse (st :input-buffer)) 'string))
 
+(defun input-insert-char (ch)
+  "Insert character at cursor position into the input buffer."
+  (let* ((buf (st :input-buffer))
+         (pos (or (st :cursor-pos) 0))
+         (s (coerce (reverse buf) 'string))
+         (new (concatenate 'string (subseq s 0 pos) (string ch) (subseq s pos))))
+    (setf (st :input-buffer) (reverse (coerce new 'list)))
+    (setf (st :cursor-pos) (1+ pos))))
+
+(defun input-delete-char ()
+  "Delete character before cursor position (standard backspace)."
+  (let* ((buf (st :input-buffer))
+         (pos (or (st :cursor-pos) 0)))
+    (when (and buf (> pos 0))
+      (let* ((s (coerce (reverse buf) 'string))
+             (new (concatenate 'string (subseq s 0 (1- pos)) (subseq s pos))))
+        (setf (st :input-buffer) (reverse (coerce new 'list)))
+        (setf (st :cursor-pos) (1- pos))))))
+
 (defun add-msg (role content)
   (push (list :role role :content content :time (now)) (st :messages))
   (setf (st :dirty) (list t t nil)))
diff --git a/lisp/gateway-tui-view.lisp b/lisp/gateway-tui-view.lisp
index 7c9be8a..c9af937 100644
--- a/lisp/gateway-tui-view.lisp
+++ b/lisp/gateway-tui-view.lisp
@@ -87,10 +87,12 @@ Returns list of trimmed strings. Single words wider than width are split."
 (defun view-input (win)
   (let* ((text (input-string))
          (w (or (width win) 78))
-         (clip (min (length text) (1- w))))
+         (pos (or (st :cursor-pos) 0))
+         (display-start (max 0 (- pos (1- w))))
+         (visible (subseq text display-start (min (length text) (+ display-start w)))))
     (clear win)
-    (add-string win (format nil "~a " text) :y 0 :x 0 :n (1- w) :fgcolor (theme-color :input))
-    (setf (cursor-position win) (list 0 clip)))
+    (add-string win (format nil "~a " visible) :y 0 :x 0 :n (1- w) :fgcolor (theme-color :input))
+    (setf (cursor-position win) (list 0 (min (- pos display-start) (1- w)))))
   (refresh win))
 
 (defun redraw (sw cw ch iw)
diff --git a/org/gateway-tui-main.org b/org/gateway-tui-main.org
index 7de71b4..8739d07 100644
--- a/org/gateway-tui-main.org
+++ b/org/gateway-tui-main.org
@@ -122,8 +122,9 @@ Event handlers + daemon I/O + main loop.
                    (setf (st :busy) t)
                    (send-daemon (list :type :event
                                      :payload (list :sensor :user-input :text text)))))
-                (setf (st :input-buffer) nil)
-                (setf (st :dirty) (list t t t))))))
+                 (setf (st :input-buffer) nil)
+                 (setf (st :cursor-pos) 0)
+                 (setf (st :dirty) (list t t t))))))
        ;; Tab — command completion
        ((or (eql ch 9) (eq ch :tab))
         (let ((text (input-string)))
@@ -138,11 +139,21 @@ Event handlers + daemon I/O + main loop.
                 (when (member match '("/eval" "/focus" "/scope") :test #'string=)
                   (push #\Space (st :input-buffer)))
                 (setf (st :dirty) (list nil nil t)))))))
-       ;; Backspace
-       ((or (eq ch :backspace) (eql ch 127) (eql ch 8)
-            (eql ch #\Backspace))
-       (when (st :input-buffer) (pop (st :input-buffer)))
-       (setf (st :dirty) (list nil nil t)))
+        ;; Backspace
+        ((or (eq ch :backspace) (eql ch 127) (eql ch 8)
+             (eql ch #\Backspace))
+        (input-delete-char)
+        (setf (st :dirty) (list nil nil t)))
+       ;; Left arrow
+       ((or (eq ch :left) (eql ch 260))
+        (when (> (or (st :cursor-pos) 0) 0)
+          (decf (st :cursor-pos))
+          (setf (st :dirty) (list nil nil t))))
+       ;; Right arrow
+       ((or (eq ch :right) (eql ch 261))
+        (when (< (or (st :cursor-pos) 0) (length (st :input-buffer)))
+          (incf (st :cursor-pos))
+          (setf (st :dirty) (list nil nil t))))
       ;; Up arrow
       ((or (eq ch :up) (eql ch 259))
        (let* ((h (st :input-history)) (p (st :input-hpos)))
@@ -169,15 +180,15 @@ Event handlers + daemon I/O + main loop.
       ((or (eq ch :npage) (eql ch 338))
        (setf (st :scroll-offset) (max 0 (- (st :scroll-offset) 5)))
        (setf (st :dirty) (list nil t nil)))
-      ;; Printable
-      (t
-       (let ((chr (typecase ch
-                    (character ch)
-                    (integer (code-char ch))
-                    (t nil))))
-         (when (and chr (graphic-char-p chr))
-           (push chr (st :input-buffer))
-           (setf (st :dirty) (list nil nil t))))))))
+       ;; Printable
+       (t
+        (let ((chr (typecase ch
+                     (character ch)
+                     (integer (code-char ch))
+                     (t nil))))
+          (when (and chr (graphic-char-p chr))
+            (input-insert-char chr)
+            (setf (st :dirty) (list nil nil t))))))))
 
 (defun on-daemon-msg (msg)
   (let* ((payload (getf msg :payload))
diff --git a/org/gateway-tui-model.org b/org/gateway-tui-model.org
index c86e4ad..65ee4da 100644
--- a/org/gateway-tui-model.org
+++ b/org/gateway-tui-model.org
@@ -48,7 +48,7 @@ All state mutation flows through event handlers in the controller.
   (setf *state*
         (list :running t :mode :chat :connected nil :stream nil
               :input-buffer nil :input-history nil :input-hpos 0
-              :messages nil :scroll-offset 0 :busy nil
+              :messages nil :scroll-offset 0 :busy nil :cursor-pos 0
               :dirty (list nil nil nil))))
 #+end_src
 
@@ -62,6 +62,25 @@ All state mutation flows through event handlers in the controller.
 (defun input-string ()
   (coerce (reverse (st :input-buffer)) 'string))
 
+(defun input-insert-char (ch)
+  "Insert character at cursor position into the input buffer."
+  (let* ((buf (st :input-buffer))
+         (pos (or (st :cursor-pos) 0))
+         (s (coerce (reverse buf) 'string))
+         (new (concatenate 'string (subseq s 0 pos) (string ch) (subseq s pos))))
+    (setf (st :input-buffer) (reverse (coerce new 'list)))
+    (setf (st :cursor-pos) (1+ pos))))
+
+(defun input-delete-char ()
+  "Delete character before cursor position (standard backspace)."
+  (let* ((buf (st :input-buffer))
+         (pos (or (st :cursor-pos) 0)))
+    (when (and buf (> pos 0))
+      (let* ((s (coerce (reverse buf) 'string))
+             (new (concatenate 'string (subseq s 0 (1- pos)) (subseq s pos))))
+        (setf (st :input-buffer) (reverse (coerce new 'list)))
+        (setf (st :cursor-pos) (1- pos))))))
+
 (defun add-msg (role content)
   (push (list :role role :content content :time (now)) (st :messages))
   (setf (st :dirty) (list t t nil)))
diff --git a/org/gateway-tui-view.org b/org/gateway-tui-view.org
index 512d59f..e725ffb 100644
--- a/org/gateway-tui-view.org
+++ b/org/gateway-tui-view.org
@@ -115,10 +115,12 @@ Returns list of trimmed strings. Single words wider than width are split."
 (defun view-input (win)
   (let* ((text (input-string))
          (w (or (width win) 78))
-         (clip (min (length text) (1- w))))
+         (pos (or (st :cursor-pos) 0))
+         (display-start (max 0 (- pos (1- w))))
+         (visible (subseq text display-start (min (length text) (+ display-start w)))))
     (clear win)
-    (add-string win (format nil "~a " text) :y 0 :x 0 :n (1- w) :fgcolor (theme-color :input))
-    (setf (cursor-position win) (list 0 clip)))
+    (add-string win (format nil "~a " visible) :y 0 :x 0 :n (1- w) :fgcolor (theme-color :input))
+    (setf (cursor-position win) (list 0 (min (- pos display-start) (1- w)))))
   (refresh win))
 #+end_src