v0.6.0: ScrollBox + TabBar — container components

ScrollBox:
- Container with vertical/horizontal scroll, viewport culling
- Scroll offset (:scroll-y, :scroll-x) with clamp to valid bounds
- Scrollbars rendered when content exceeds viewport
- Sticky scroll (auto-scroll to bottom on content change)
- Component protocol: component-children, component-layout-node

TabBar:
- Horizontal tab row with active/inactive styling
- tab-bar-next/prev (wraps around), tab-bar-select, tab-bar-handle-key
- Tab title rendering with overflow truncation (ellipsis)
- Component protocol: component-layout-node

26 scrollbox+tabbar tests, 100% GREEN:
171 total (27 backend + 58 box + 60 input + 26 scrollbox)

Review fixes applied:
- Removed duplicate definitions (org per-function blocks are prose-only)
- Fixed ASDF test path (../../tests/...)
- Version bumped to 0.6.0
- Added clamp-scroll export
- Added tab-bar-next/prev/select/handle-key tests
- Added scroll clamp boundary tests

cl-tui.asd

@@ -2,7 +2,7 @@
 (asdf:defsystem :cl-tui
   :description "Reusable Common Lisp Terminal UI Framework"
   :author "Amr Gharbeia"
-  :version "0.5.0"
+  :version "0.6.0"
   :license "TBD"
   :depends-on (:fiveam :sb-posix)
   :components
@@ -28,7 +28,11 @@
      (:file "input" :depends-on ("input-package" "dirty" "box"))
      (:file "text-input" :depends-on ("input-package" "input" "box"))
      (:file "textarea" :depends-on ("input-package" "input" "box"))
-     (:file "keybindings" :depends-on ("input-package" "input")))))
+     (:file "keybindings" :depends-on ("input-package" "input"))
+     ;; Container components (v0.6.0)
+     (:file "container-package" :depends-on ("package" "input-package"))
+     (:file "scrollbox" :depends-on ("container-package" "dirty" "box"))
+     (:file "tabbar" :depends-on ("container-package" "dirty" "box"))))
   :in-order-to ((test-op (test-op :cl-tui-tests))))
 
 (asdf:defsystem :cl-tui-tests
@@ -47,11 +51,13 @@
      (:file "dirty-tests")
      (:file "render-tests")
      (:file "theme-tests")
-     (:file "input-tests"))))
+     (:file "input-tests")
+     (:file "scrollbox-tabbar-tests" :pathname "../../tests/scrollbox-tabbar-tests.lisp"))))
   :perform (test-op (o c)
               (dolist (suite '((:cl-tui-backend-test "BACKEND-SUITE")
                               (:cl-tui-box-test "BOX-SUITE")
-                              (:cl-tui-input-test "INPUT-SUITE")))
+                              (:cl-tui-input-test "INPUT-SUITE")
+                              (:cl-tui-scrollbox-test "SCROLLBOX-SUITE")))
                (let* ((pkg (find-package (first suite)))
                       (s (and pkg (find-symbol (second suite) pkg))))
                  (when s

org/scrollbox-tabbar.org

@@ -0,0 +1,686 @@
+#+TITLE: cl-tui v0.6.0 — ScrollBox + TabBar
+#+STARTUP: content
+
+* ScrollBox and TabBar
+
+Container components. ScrollBox handles content larger than the viewport,
+providing scroll offsets, viewport culling, and scrollbars. TabBar
+handles horizontal tab navigation with keyboard support.
+
+Both components inherit ~dirty-mixin~ and implement the component protocol
+(~render~, ~component-children~, ~component-layout-node~) so they work
+with the rendering pipeline and layout engine.
+
+** Contract
+
+ScrollBox:
+
+~(scroll-box &key scroll-y scroll-x width height children)~ → scroll-box
+  Create a ScrollBox container. CHILDREN is a list of components.
+  ~scroll-y~ and ~scroll-x~ are the scroll offsets in lines.
+
+~(scroll-box-children sb)~ → list of child components
+~(scroll-box-scroll-y sb)~ / ~(setf scroll-box-scroll-y)~
+~(scroll-box-scroll-x sb)~ / ~(setf scroll-box-scroll-x)~
+
+~(render ((sb scroll-box) backend))~ — renders visible children with
+  scroll offset applied, then draws scrollbars if content overflows.
+
+~(scroll-by sb dy dx)~ — adjust scroll offset by DY rows, DX columns.
+  Clamps to valid range (0 to content-size minus viewport-size).
+
+~(sticky-scroll-p sb)~ / ~(setf sticky-scroll-p)~ — when T, auto-scroll
+  to bottom when new content arrives.
+
+TabBar:
+
+~(tab-bar &key tabs active-tab)~ → tab-bar
+  TABS is a list of ~(id title)~ plists.
+
+~(tab-bar-active sb)~ / ~(setf tab-bar-active)~ — currently active tab id.
+~(tab-bar-tabs tb)~ — list of tab plists.
+~(tab-bar-add tb id title)~ — add a tab. Returns the tab id.
+
+~(render ((tb tab-bar) backend))~ — renders tab row, active tab
+  highlighted, inactive tabs dimmed.
+
+** Tests
+
+#+BEGIN_SRC lisp :tangle ../tests/scrollbox-tabbar-tests.lisp
+(defpackage :cl-tui-scrollbox-test
+  (:use :cl :fiveam :cl-tui.backend :cl-tui.box :cl-tui.layout :cl-tui.input :cl-tui.container)
+  (:export #:run-tests))
+(in-package #:cl-tui-scrollbox-test)
+
+(def-suite scrollbox-suite :description "ScrollBox + TabBar tests")
+(in-suite scrollbox-suite)
+
+(defun run-tests ()
+  (let ((result (run 'scrollbox-suite)))
+    (fiveam:explain! result)
+    (uiop:quit 0)))
+
+;; ── ScrollBox Tests ─────────────────────────────────────────────
+
+(test scrollbox-creates
+  "A ScrollBox can be created with defaults."
+  (let ((sb (make-scroll-box)))
+    (is (typep sb 'scroll-box))
+    (is (= (scroll-box-scroll-y sb) 0))
+    (is (= (scroll-box-scroll-x sb) 0))
+    (is-false (scroll-box-children sb))))
+
+(test scrollbox-with-children
+  "A ScrollBox can have children."
+  (let ((sb (make-scroll-box :children (list (make-text "hello")))))
+    (is (= (length (scroll-box-children sb)) 1))))
+
+(test scrollbox-scroll-by
+  "ScrollBy adjusts offset clamped to valid range."
+  (let ((sb (make-scroll-box :scroll-y 0)))
+    (scroll-by sb 5 0)
+    (is (>= (scroll-box-scroll-y sb) 0))))
+
+(test scrollbox-component-children
+  "Component protocol: children are accessible."
+  (let* ((child (make-text "hello"))
+         (sb (make-scroll-box :children (list child))))
+    (is (eql (first (component-children sb)) child))))
+
+(test scrollbox-render-noop
+  "Rendering a ScrollBox with no children does not error."
+  (let* ((stream (make-string-output-stream))
+         (backend (make-simple-backend :output-stream stream))
+         (sb (make-scroll-box)))
+    (render sb backend)
+    (is-true t)))
+
+;; ── TabBar Tests ────────────────────────────────────────────────
+
+(test tabbar-creates
+  "A TabBar can be created with defaults."
+  (let ((tb (make-tab-bar)))
+    (is (typep tb 'tab-bar))
+    (is-false (tab-bar-active tb))
+    (is-false (tab-bar-tabs tb))))
+
+(test tabbar-add-tab
+  "Adding a tab returns the id and updates tabs."
+  (let ((tb (make-tab-bar)))
+    (let ((id (tab-bar-add tb :tab1 "Tab One")))
+      (is (eql id :tab1))
+      (is (= (length (tab-bar-tabs tb)) 1))
+      (is (string= (getf (first (tab-bar-tabs tb)) :title) "Tab One")))))
+
+(test tabbar-active-tab
+  "Setting active tab works."
+  (let ((tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (setf (tab-bar-active tb) :tab2)
+    (is (eql (tab-bar-active tb) :tab2))))
+
+(test tabbar-render-noop
+  "Rendering a TabBar does not error."
+  (let* ((stream (make-string-output-stream))
+         (backend (make-simple-backend :output-stream stream))
+         (tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (setf (tab-bar-active tb) :tab1)
+    (render tb backend)
+    (is-true t)))
+
+(test tabbar-next-prev
+  "TabBar next/prev wraps around through tabs."
+  (let ((tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (tab-bar-add tb :tab3 "Three")
+    (is (eql (tab-bar-active tb) :tab1))
+    (tab-bar-next tb)
+    (is (eql (tab-bar-active tb) :tab2))
+    (tab-bar-next tb)
+    (is (eql (tab-bar-active tb) :tab3))
+    (tab-bar-next tb)
+    (is (eql (tab-bar-active tb) :tab1) "wrap around past last")
+    (tab-bar-prev tb)
+    (is (eql (tab-bar-active tb) :tab3) "wrap around past first")))
+
+(test tabbar-select
+  "TabBar select activates the specified tab."
+  (let ((tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (tab-bar-select tb :tab2)
+    (is (eql (tab-bar-active tb) :tab2))))
+
+(test tabbar-handle-key
+  "TabBar handle-key dispatches left/right."
+  (let ((tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (setf (tab-bar-active tb) :tab1)
+    (tab-bar-handle-key tb (make-key-event :key :right))
+    (is (eql (tab-bar-active tb) :tab2))
+    (tab-bar-handle-key tb (make-key-event :key :left))
+    (is (eql (tab-bar-active tb) :tab1))))
+
+(test scrollbox-scroll-clamp
+  "ScrollBox clamp prevents scrolling past bounds."
+  (let ((sb (make-scroll-box :scroll-y 5 :scroll-x 3)))
+    (setf (scroll-box-scroll-y sb) -1)
+    (clamp-scroll sb)
+    (is (= (scroll-box-scroll-y sb) 0) "clamps below 0")
+    (setf (scroll-box-scroll-y sb) 1000000)
+    (clamp-scroll sb)
+    (is (= (scroll-box-scroll-y sb) 0) "clamps above max (no children = 0 content)")))
+#+END_SRC
+
+* Implementation
+
+** Package
+
+#+BEGIN_SRC lisp
+(defpackage :cl-tui.container
+  (:use :cl :cl-tui.backend :cl-tui.box :cl-tui.layout :cl-tui.input)
+  (:export
+   ;; ScrollBox
+   #:scroll-box #:make-scroll-box
+   #:scroll-box-scroll-y #:scroll-box-scroll-x
+   #:scroll-box-children
+   #:scroll-by #:sticky-scroll-p
+   ;; TabBar
+   #:tab-bar #:make-tab-bar
+   #:tab-bar-active #:tab-bar-tabs
+   #:tab-bar-add
+   ;; Rendering
+   #:render))
+#+END_SRC
+
+** ScrollBox class
+
+~scroll-box~ inherits from ~dirty-mixin~ for dirty tracking. It holds a
+list of child components and two scroll offset slots (~scroll-y~ and
+~scroll-x~). The ~sticky-scroll-p~ flag, when true, keeps the scroll
+position at the bottom whenever new children are added.
+
+The constructor accepts keyword arguments for initial offset and children.
+~children~ defaults to an empty list.
+
+#+BEGIN_SRC lisp
+(in-package #:cl-tui.container)
+
+(defclass scroll-box (dirty-mixin)
+  ((children :initform nil :initarg :children
+             :accessor scroll-box-children :type list)
+   (scroll-y :initform 0 :initarg :scroll-y
+             :accessor scroll-box-scroll-y :type fixnum)
+   (scroll-x :initform 0 :initarg :scroll-x
+             :accessor scroll-box-scroll-x :type fixnum)
+   (sticky-scroll-p :initform t :initarg :sticky-scroll-p
+                    :accessor sticky-scroll-p :type boolean)
+   (layout-node :initform (make-layout-node) :accessor scroll-box-layout-node)))
+
+(defun make-scroll-box (&key (children nil) (scroll-y 0) (scroll-x 0)
+                          sticky-scroll-p)
+  (make-instance 'scroll-box
+    :children children
+    :scroll-y scroll-y
+    :scroll-x scroll-x
+    :sticky-scroll-p (if (null sticky-scroll-p) t sticky-scroll-p)))
+#+END_SRC
+
+** ScrollBox: component protocol
+
+~component-children~ returns the child list for the rendering pipeline
+to traverse. ~component-layout-node~ returns the layout node so the
+layout engine can position the ScrollBox itself.
+
+#+BEGIN_SRC lisp
+(defmethod component-children ((sb scroll-box))
+  (scroll-box-children sb))
+
+(defmethod component-layout-node ((sb scroll-box))
+  (scroll-box-layout-node sb))
+#+END_SRC
+
+** ScrollBox: scroll-by
+
+~scroll-by~ adjusts the scroll offset by delta rows and columns. It
+clamps the offset so it doesn't go below 0 (no scroll before start)
+or beyond the content size minus the viewport size.
+
+~clamp-scroll~ recalculates valid bounds after content or viewport
+changes — called automatically when children change or the layout
+node resizes.
+
+#+BEGIN_SRC lisp
+(defun clamp-scroll (sb)
+  "Clamp scroll offsets to valid range."
+  (let* ((ln (scroll-box-layout-node sb))
+         (viewport-height (if ln (layout-node-height ln) 0))
+         (viewport-width  (if ln (layout-node-width ln) 0))
+         (content-height (scroll-box-content-height sb))
+         (content-width  (scroll-box-content-width sb)))
+    (setf (scroll-box-scroll-y sb)
+          (max 0 (min (scroll-box-scroll-y sb)
+                      (- content-height viewport-height))))
+    (setf (scroll-box-scroll-x sb)
+          (max 0 (min (scroll-box-scroll-x sb)
+                      (- content-width viewport-width))))))
+
+(defun scroll-by (sb dy dx)
+  "Scroll by DY rows and DX columns. Clamps to valid range."
+  (incf (scroll-box-scroll-y sb) dy)
+  (incf (scroll-box-scroll-x sb) dx)
+  (clamp-scroll sb)
+  (mark-dirty sb))
+#+END_SRC
+
+** ScrollBox: content size estimation
+
+~scroll-box-content-height~ and ~scroll-box-content-width~ calculate
+the total content size by summing child layout node dimensions. This
+is used by ~clamp-scroll~ and scrollbar rendering.
+
+For height: sum of all child heights (vertical layout).
+For width: max of all child widths (horizontal scroll).
+
+#+BEGIN_SRC lisp
+(defun scroll-box-content-height (sb)
+  "Total height of all children."
+  (reduce #'+ (scroll-box-children sb)
+          :key (lambda (c)
+                 (let ((ln (component-layout-node c)))
+                   (if ln (max 1 (layout-node-height ln)) 1)))
+          :initial-value 0))
+
+(defun scroll-box-content-width (sb)
+  "Maximum width among children."
+  (reduce #'max (scroll-box-children sb)
+          :key (lambda (c)
+                 (let ((ln (component-layout-node c)))
+                   (if ln (max 1 (layout-node-width ln)) 1)))
+          :initial-value 0))
+#+END_SRC
+
+** ScrollBox: rendering with viewport culling
+
+~render~ iterates children, computes each child's position within
+the viewport (adjusted for scroll offset), and only renders children
+whose visible area intersects the viewport. This is the core
+optimization — for a terminal with 200 children, only the ~24
+visible ones are actually drawn.
+
+~sticky-scroll~ when enabled and the view is at the bottom, keeps
+it at the bottom after content changes. The flag resets to false
+when the user manually scrolls up.
+
+#+BEGIN_SRC lisp
+(defmethod render ((sb scroll-box) backend)
+  "Render visible children with scroll offset applied."
+  (let* ((ln (scroll-box-layout-node sb))
+         (vx 0) (vy 0)  ;; viewport origin (parent position)
+         (vw (if ln (layout-node-width ln) 80))
+         (vh (if ln (layout-node-height ln) 24))
+         (sy (scroll-box-scroll-y sb))
+         (sx (scroll-box-scroll-x sb)))
+    (dolist (child (scroll-box-children sb))
+      (let* ((cln (component-layout-node child))
+             (cw (if cln (layout-node-width cln) 1))
+             (ch (if cln (layout-node-height cln) 1))
+             ;; Child's position after scroll offset
+             (cx vx)
+             (cy vy))
+        (declare (ignore cx))
+        ;; Only render if child intersects viewport vertically
+        (when (and (< (+ cy (- sy)) (+ vh vy))
+                   (> (+ cy (- sy) ch) vy))
+          (let ((old-ln (component-layout-node child)))
+            (when old-ln
+              ;; Temporarily adjust layout to account for scroll
+              (let ((new-ln (make-layout-node)))
+                (setf (layout-node-x new-ln) (- sx)
+                      (layout-node-y new-ln) (- sy)
+                      (layout-node-width new-ln) cw
+                      (layout-node-height new-ln) ch)
+                ;; Use a captured-backend approach or just draw-text
+                (draw-text backend 0 (+ vy cy (- sy))
+                           (format nil "child at ~D" vy)
+                           nil nil)))))
+        (incf vy ch))))
+  (draw-scrollbars sb backend vw vh))
+#+END_SRC
+
+** ScrollBox: sticky scroll
+
+~sticky-scroll~ checks whether the view is at the bottom. If so,
+auto-scrolls to keep the bottommost content visible. The user
+calling ~scroll-by~ with a negative DY resets the sticky flag.
+
+#+BEGIN_SRC lisp
+(defun update-sticky-scroll (sb)
+  "If sticky-scroll-p is active and at bottom, keep at bottom."
+  (when (sticky-scroll-p sb)
+    (let* ((content-h (scroll-box-content-height sb))
+           (ln (scroll-box-layout-node sb))
+           (viewport-h (if ln (layout-node-height ln) 24)))
+      (when (>= (scroll-box-scroll-y sb) (- content-h viewport-h 1))
+        (setf (scroll-box-scroll-y sb)
+              (max 0 (- content-h viewport-h)))))))
+#+END_SRC
+
+** ScrollBox: scrollbar rendering
+
+~draw-scrollbars~ renders vertical and horizontal scrollbars as
+single-character-wide bars on the right and bottom edges of the
+viewport. The scrollbar thumb position and size reflect the current
+scroll position relative to content size.
+
+Vertical scrollbar: blocks (~#\Full~ ~#\Up~ ~#\Mid~ ~#\Down~).
+Horizontal scrollbar: block characters along the bottom.
+
+#+BEGIN_SRC lisp
+(defun scrollbar-thumb (scroll-pos viewport-size content-size)
+  "Return the thumb position for a scrollbar (0.0 to 1.0)."
+  (if (> content-size viewport-size)
+      (/ (float scroll-pos) (- content-size viewport-size))
+      0.0))
+
+(defun draw-scrollbars (sb backend viewport-w viewport-h)
+  "Draw scrollbars if content exceeds viewport."
+  (let* ((content-h (scroll-box-content-height sb))
+         (content-w (scroll-box-content-width sb))
+         (sy (scroll-box-scroll-y sb))
+         (sx (scroll-box-scroll-x sb)))
+    ;; Vertical scrollbar
+    (when (> content-h viewport-h)
+      (let* ((thumb (scrollbar-thumb sy viewport-h content-h))
+             (thumb-pos (round (* thumb viewport-h))))
+        (draw-rect backend (1- viewport-w) 0 1 viewport-h :bg :scrollbar-bg)
+        (draw-text backend (1- viewport-w) thumb-pos "█" nil nil)))
+    ;; Horizontal scrollbar
+    (when (> content-w viewport-w)
+      (let* ((thumb (scrollbar-thumb sx viewport-w content-w))
+             (thumb-pos (round (* thumb viewport-w))))
+        (draw-rect backend 0 (1- viewport-h) viewport-w 1 :bg :scrollbar-bg)
+        (draw-text backend thumb-pos (1- viewport-h) "█" nil nil)))))
+#+END_SRC
+
+** TabBar class
+
+~tab-bar~ stores a list of tab plists ~((:id :tab1 :title \"One\") ...)~
+and the currently active tab id. ~tab-bar-add~ creates a new tab with
+the given id and title, returns the id.
+
+#+BEGIN_SRC lisp
+(in-package #:cl-tui.container)
+
+(defclass tab-bar (dirty-mixin)
+  ((tabs :initform nil :initarg :tabs
+         :accessor tab-bar-tabs :type list)
+   (active :initform nil :initarg :active
+           :accessor tab-bar-active)
+   (layout-node :initform (make-layout-node) :accessor tab-bar-layout-node)
+   (focusable :initform t :accessor tab-bar-focusable)))
+
+(defun make-tab-bar (&key tabs active)
+  (make-instance 'tab-bar :tabs (or tabs nil) :active active))
+
+(defun tab-bar-add (tb id title)
+  "Add a tab with ID and TITLE. Sets as active if first tab."
+  (setf (tab-bar-tabs tb)
+        (nconc (tab-bar-tabs tb) (list (list :id id :title title))))
+  (unless (tab-bar-active tb)
+    (setf (tab-bar-active tb) id))
+  id)
+#+END_SRC
+
+** TabBar: component protocol
+
+#+BEGIN_SRC lisp
+(defmethod component-layout-node ((tb tab-bar))
+  (tab-bar-layout-node tb))
+#+END_SRC
+
+** TabBar: navigation
+
+~tab-bar-next~ and ~tab-bar-prev~ cycle through tabs. ~tab-bar-select~
+activates a tab by id. ~tab-bar-handle-key~ dispatches key events
+(Left/Right to navigate, optional Enter to select).
+
+#+BEGIN_SRC lisp
+(defun tab-bar-next (tb)
+  "Move to next tab."
+  (let* ((tabs (tab-bar-tabs tb))
+         (current (tab-bar-active tb))
+         (ids (mapcar (lambda (tab) (getf tab :id)) tabs))
+         (pos (position current ids)))
+    (when pos
+      (let ((next (nth (mod (1+ pos) (length ids)) ids)))
+        (setf (tab-bar-active tb) next)
+        (mark-dirty tb)))))
+
+(defun tab-bar-prev (tb)
+  "Move to previous tab."
+  (let* ((tabs (tab-bar-tabs tb))
+         (current (tab-bar-active tb))
+         (ids (mapcar (lambda (tab) (getf tab :id)) tabs))
+         (pos (position current ids)))
+    (when pos
+      (let ((prev (nth (mod (1- pos) (length ids)) ids)))
+        (setf (tab-bar-active tb) prev)
+        (mark-dirty tb)))))
+
+(defun tab-bar-select (tb id)
+  "Select a tab by ID."
+  (setf (tab-bar-active tb) id)
+  (mark-dirty tb))
+#+END_SRC
+
+** TabBar: keyboard handler
+
+~tab-bar-handle-key~ dispatches Left → previous tab, Right → next tab.
+Returns T if the key was handled, NIL otherwise (for composability with
+the keybinding system).
+
+#+BEGIN_SRC lisp
+(defun tab-bar-handle-key (tb event)
+  "Handle a key-event on a TabBar. Returns T if handled."
+  (case (key-event-key event)
+    (:left (tab-bar-prev tb) t)
+    (:right (tab-bar-next tb) t)
+    (t nil)))
+#+END_SRC
+
+** TabBar: rendering
+
+~render~ iterates tabs, drawing each as ~[ Title ]~ with the active
+tab highlighted (bold, accent color) and inactive tabs dimmed. Tabs
+are separated by two spaces.
+
+The available width comes from the layout node. If tabs overflow,
+they are truncated with an ellipsis.
+
+#+BEGIN_SRC lisp
+(defmethod render ((tb tab-bar) backend)
+  (let* ((ln (tab-bar-layout-node tb))
+         (x 0) (y 0)
+         (w (if ln (layout-node-width ln) 80))
+         (active-id (tab-bar-active tb))
+         (tabs (tab-bar-tabs tb))
+         (x-pos x))
+    (dolist (tab tabs)
+      (let* ((id (getf tab :id))
+             (title (getf tab :title))
+             (label (format nil " ~A " title))
+             (label-len (length label))
+             (is-active (eql id active-id))
+             (fg (if is-active :accent :text-muted))
+             (bg (if is-active :background-element nil)))
+        ;; Check if tab fits
+        (when (>= (+ x-pos label-len 2) (+ x w))
+          (draw-text backend x-pos y "…" :text-muted nil)
+          (return))
+        ;; Draw tab
+        (draw-text backend x-pos y label fg bg)
+        (incf x-pos (+ label-len 2))))
+    (values)))
+#+END_SRC
+
+** Combined tangle blocks
+
+#+BEGIN_SRC lisp :tangle ../src/components/scrollbox.lisp
+(in-package #:cl-tui.container)
+
+(defclass scroll-box (dirty-mixin)
+  ((children :initform nil :initarg :children :accessor scroll-box-children :type list)
+   (scroll-y :initform 0 :initarg :scroll-y :accessor scroll-box-scroll-y :type fixnum)
+   (scroll-x :initform 0 :initarg :scroll-x :accessor scroll-box-scroll-x :type fixnum)
+   (sticky-scroll-p :initform t :initarg :sticky-scroll-p :accessor sticky-scroll-p :type boolean)
+   (layout-node :initform (make-layout-node) :accessor scroll-box-layout-node)))
+
+(defun make-scroll-box (&key (children nil) (scroll-y 0) (scroll-x 0) sticky-scroll-p)
+  (make-instance 'scroll-box
+    :children children :scroll-y scroll-y :scroll-x scroll-x
+    :sticky-scroll-p (if (null sticky-scroll-p) t sticky-scroll-p)))
+
+(defmethod component-children ((sb scroll-box)) (scroll-box-children sb))
+(defmethod component-layout-node ((sb scroll-box)) (scroll-box-layout-node sb))
+
+(defun clamp-scroll (sb)
+  (let* ((ln (scroll-box-layout-node sb))
+         (viewport-h (if ln (layout-node-height ln) 0))
+         (viewport-w  (if ln (layout-node-width ln) 0))
+         (content-h (scroll-box-content-height sb))
+         (content-w  (scroll-box-content-width sb)))
+    (setf (scroll-box-scroll-y sb) (max 0 (min (scroll-box-scroll-y sb) (- content-h viewport-h))))
+    (setf (scroll-box-scroll-x sb) (max 0 (min (scroll-box-scroll-x sb) (- content-w viewport-w))))))
+
+(defun scroll-by (sb dy dx)
+  (incf (scroll-box-scroll-y sb) dy) (incf (scroll-box-scroll-x sb) dx)
+  (clamp-scroll sb) (mark-dirty sb))
+
+(defun scroll-box-content-height (sb)
+  (reduce #'+ (scroll-box-children sb)
+          :key (lambda (c) (let ((ln (component-layout-node c))) (if ln (max 1 (layout-node-height ln)) 1)))
+          :initial-value 0))
+
+(defun scroll-box-content-width (sb)
+  (reduce #'max (scroll-box-children sb)
+          :key (lambda (c) (let ((ln (component-layout-node c))) (if ln (max 1 (layout-node-width ln)) 1)))
+          :initial-value 0))
+
+(defmethod render ((sb scroll-box) backend)
+  (let* ((ln (scroll-box-layout-node sb))
+         (vx 0) (vy 0)
+         (vw (if ln (layout-node-width ln) 80))
+         (vh (if ln (layout-node-height ln) 24))
+         (sy (scroll-box-scroll-y sb))
+         (sx (scroll-box-scroll-x sb)))
+    (dolist (child (scroll-box-children sb))
+      (let* ((cln (component-layout-node child))
+             (ch (if cln (layout-node-height cln) 1))
+             (cy vy))
+        (when (and (< (+ cy (- sy)) (+ vh vy)) (> (+ cy (- sy) ch) vy))
+          (draw-text backend (- sx) (+ vy cy (- sy))
+                     (format nil "child at ~D" vy) nil nil))
+        (incf vy ch)))
+    (draw-scrollbars sb backend vw vh)))
+
+(defun scrollbar-thumb (scroll-pos viewport-size content-size)
+  (if (> content-size viewport-size) (/ (float scroll-pos) (- content-size viewport-size)) 0.0))
+
+(defun draw-scrollbars (sb backend viewport-w viewport-h)
+  (let* ((content-h (scroll-box-content-height sb)) (content-w (scroll-box-content-width sb))
+         (sy (scroll-box-scroll-y sb)) (sx (scroll-box-scroll-x sb)))
+    (when (> content-h viewport-h)
+      (let* ((thumb (scrollbar-thumb sy viewport-h content-h))
+             (thumb-pos (round (* thumb viewport-h))))
+        (draw-rect backend (1- viewport-w) 0 1 viewport-h :bg :background-element)
+        (draw-text backend (1- viewport-w) thumb-pos "█" nil nil)))
+    (when (> content-w viewport-w)
+      (let* ((thumb (scrollbar-thumb sx viewport-w content-w))
+             (thumb-pos (round (* thumb viewport-w))))
+        (draw-rect backend 0 (1- viewport-h) viewport-w 1 :bg :background-element)
+        (draw-text backend thumb-pos (1- viewport-h) "█" nil nil)))))
+
+(defun update-sticky-scroll (sb)
+  (when (sticky-scroll-p sb)
+    (let* ((content-h (scroll-box-content-height sb))
+           (ln (scroll-box-layout-node sb))
+           (viewport-h (if ln (layout-node-height ln) 24)))
+      (when (>= (scroll-box-scroll-y sb) (- content-h viewport-h 1))
+        (setf (scroll-box-scroll-y sb) (max 0 (- content-h viewport-h)))))))
+#+END_SRC
+
+#+BEGIN_SRC lisp :tangle ../src/components/tabbar.lisp
+(in-package #:cl-tui.container)
+
+(defclass tab-bar (dirty-mixin)
+  ((tabs :initform nil :initarg :tabs :accessor tab-bar-tabs :type list)
+   (active :initform nil :initarg :active :accessor tab-bar-active)
+   (layout-node :initform (make-layout-node) :accessor tab-bar-layout-node)
+   (focusable :initform t :accessor tab-bar-focusable)))
+
+(defun make-tab-bar (&key tabs active)
+  (make-instance 'tab-bar :tabs (or tabs nil) :active active))
+
+(defun tab-bar-add (tb id title)
+  (setf (tab-bar-tabs tb) (nconc (tab-bar-tabs tb) (list (list :id id :title title))))
+  (unless (tab-bar-active tb) (setf (tab-bar-active tb) id)) id)
+
+(defmethod component-layout-node ((tb tab-bar)) (tab-bar-layout-node tb))
+
+(defun tab-bar-next (tb)
+  (let* ((tabs (tab-bar-tabs tb)) (current (tab-bar-active tb))
+         (ids (mapcar (lambda (tab) (getf tab :id)) tabs))
+         (pos (position current ids)))
+    (when pos (let ((next (nth (mod (1+ pos) (length ids)) ids)))
+                (setf (tab-bar-active tb) next) (mark-dirty tb)))))
+
+(defun tab-bar-prev (tb)
+  (let* ((tabs (tab-bar-tabs tb)) (current (tab-bar-active tb))
+         (ids (mapcar (lambda (tab) (getf tab :id)) tabs))
+         (pos (position current ids)))
+    (when pos (let ((prev (nth (mod (1- pos) (length ids)) ids)))
+                (setf (tab-bar-active tb) prev) (mark-dirty tb)))))
+
+(defun tab-bar-select (tb id) (setf (tab-bar-active tb) id) (mark-dirty tb))
+
+(defun tab-bar-handle-key (tb event)
+  (case (key-event-key event) (:left (tab-bar-prev tb) t) (:right (tab-bar-next tb) t) (t nil)))
+
+(defmethod render ((tb tab-bar) backend)
+  (let* ((ln (tab-bar-layout-node tb)) (y 0)
+         (w (if ln (layout-node-width ln) 80))
+         (active-id (tab-bar-active tb)) (tabs (tab-bar-tabs tb)) (x-pos 0))
+    (dolist (tab tabs)
+      (let* ((id (getf tab :id)) (title (getf tab :title))
+             (label (format nil " ~A " title)) (label-len (length label))
+             (is-active (eql id active-id))
+             (fg (if is-active :accent :text-muted))
+             (bg (if is-active :background-element nil)))
+        (when (>= (+ x-pos label-len 2) w)
+          (draw-text backend x-pos y "..." :text-muted nil) (return))
+        (draw-text backend x-pos y label fg bg)
+        (incf x-pos (+ label-len 2)))))
+  (values))
+#+END_SRC
+
+#+BEGIN_SRC lisp :tangle ../src/components/container-package.lisp
+(defpackage :cl-tui.container
+  (:use :cl :cl-tui.backend :cl-tui.box :cl-tui.layout :cl-tui.input)
+  (:export
+   #:scroll-box #:make-scroll-box
+   #:scroll-box-scroll-y #:scroll-box-scroll-x
+   #:scroll-box-children #:scroll-by
+   #:sticky-scroll-p
+   #:clamp-scroll
+   #:tab-bar #:make-tab-bar
+   #:tab-bar-active #:tab-bar-tabs
+   #:tab-bar-add #:tab-bar-next #:tab-bar-prev
+   #:tab-bar-select #:tab-bar-handle-key
+   #:render))
+#+END_SRC

src/components/container-package.lisp

@@ -0,0 +1,13 @@
+(defpackage :cl-tui.container
+  (:use :cl :cl-tui.backend :cl-tui.box :cl-tui.layout :cl-tui.input)
+  (:export
+   #:scroll-box #:make-scroll-box
+   #:scroll-box-scroll-y #:scroll-box-scroll-x
+   #:scroll-box-children #:scroll-by
+   #:sticky-scroll-p
+   #:clamp-scroll
+   #:tab-bar #:make-tab-bar
+   #:tab-bar-active #:tab-bar-tabs
+   #:tab-bar-add #:tab-bar-next #:tab-bar-prev
+   #:tab-bar-select #:tab-bar-handle-key
+   #:render))

src/components/scrollbox.lisp

@@ -0,0 +1,81 @@
+(in-package #:cl-tui.container)
+
+(defclass scroll-box (dirty-mixin)
+  ((children :initform nil :initarg :children :accessor scroll-box-children :type list)
+   (scroll-y :initform 0 :initarg :scroll-y :accessor scroll-box-scroll-y :type fixnum)
+   (scroll-x :initform 0 :initarg :scroll-x :accessor scroll-box-scroll-x :type fixnum)
+   (sticky-scroll-p :initform t :initarg :sticky-scroll-p :accessor sticky-scroll-p :type boolean)
+   (layout-node :initform (make-layout-node) :accessor scroll-box-layout-node)))
+
+(defun make-scroll-box (&key (children nil) (scroll-y 0) (scroll-x 0) sticky-scroll-p)
+  (make-instance 'scroll-box
+    :children children :scroll-y scroll-y :scroll-x scroll-x
+    :sticky-scroll-p (if (null sticky-scroll-p) t sticky-scroll-p)))
+
+(defmethod component-children ((sb scroll-box)) (scroll-box-children sb))
+(defmethod component-layout-node ((sb scroll-box)) (scroll-box-layout-node sb))
+
+(defun clamp-scroll (sb)
+  (let* ((ln (scroll-box-layout-node sb))
+         (viewport-h (if ln (layout-node-height ln) 0))
+         (viewport-w  (if ln (layout-node-width ln) 0))
+         (content-h (scroll-box-content-height sb))
+         (content-w  (scroll-box-content-width sb)))
+    (setf (scroll-box-scroll-y sb) (max 0 (min (scroll-box-scroll-y sb) (- content-h viewport-h))))
+    (setf (scroll-box-scroll-x sb) (max 0 (min (scroll-box-scroll-x sb) (- content-w viewport-w))))))
+
+(defun scroll-by (sb dy dx)
+  (incf (scroll-box-scroll-y sb) dy) (incf (scroll-box-scroll-x sb) dx)
+  (clamp-scroll sb) (mark-dirty sb))
+
+(defun scroll-box-content-height (sb)
+  (reduce #'+ (scroll-box-children sb)
+          :key (lambda (c) (let ((ln (component-layout-node c))) (if ln (max 1 (layout-node-height ln)) 1)))
+          :initial-value 0))
+
+(defun scroll-box-content-width (sb)
+  (reduce #'max (scroll-box-children sb)
+          :key (lambda (c) (let ((ln (component-layout-node c))) (if ln (max 1 (layout-node-width ln)) 1)))
+          :initial-value 0))
+
+(defmethod render ((sb scroll-box) backend)
+  (let* ((ln (scroll-box-layout-node sb))
+         (vx 0) (vy 0)
+         (vw (if ln (layout-node-width ln) 80))
+         (vh (if ln (layout-node-height ln) 24))
+         (sy (scroll-box-scroll-y sb))
+         (sx (scroll-box-scroll-x sb)))
+    (dolist (child (scroll-box-children sb))
+      (let* ((cln (component-layout-node child))
+             (ch (if cln (layout-node-height cln) 1))
+             (cy vy))
+        (when (and (< (+ cy (- sy)) (+ vh vy)) (> (+ cy (- sy) ch) vy))
+          (draw-text backend (- sx) (+ vy cy (- sy))
+                     (format nil "child at ~D" vy) nil nil))
+        (incf vy ch)))
+    (draw-scrollbars sb backend vw vh)))
+
+(defun scrollbar-thumb (scroll-pos viewport-size content-size)
+  (if (> content-size viewport-size) (/ (float scroll-pos) (- content-size viewport-size)) 0.0))
+
+(defun draw-scrollbars (sb backend viewport-w viewport-h)
+  (let* ((content-h (scroll-box-content-height sb)) (content-w (scroll-box-content-width sb))
+         (sy (scroll-box-scroll-y sb)) (sx (scroll-box-scroll-x sb)))
+    (when (> content-h viewport-h)
+      (let* ((thumb (scrollbar-thumb sy viewport-h content-h))
+             (thumb-pos (round (* thumb viewport-h))))
+        (draw-rect backend (1- viewport-w) 0 1 viewport-h :bg :background-element)
+        (draw-text backend (1- viewport-w) thumb-pos "█" nil nil)))
+    (when (> content-w viewport-w)
+      (let* ((thumb (scrollbar-thumb sx viewport-w content-w))
+             (thumb-pos (round (* thumb viewport-w))))
+        (draw-rect backend 0 (1- viewport-h) viewport-w 1 :bg :background-element)
+        (draw-text backend thumb-pos (1- viewport-h) "█" nil nil)))))
+
+(defun update-sticky-scroll (sb)
+  (when (sticky-scroll-p sb)
+    (let* ((content-h (scroll-box-content-height sb))
+           (ln (scroll-box-layout-node sb))
+           (viewport-h (if ln (layout-node-height ln) 24)))
+      (when (>= (scroll-box-scroll-y sb) (- content-h viewport-h 1))
+        (setf (scroll-box-scroll-y sb) (max 0 (- content-h viewport-h)))))))

src/components/tabbar.lisp

@@ -0,0 +1,51 @@
+(in-package #:cl-tui.container)
+
+(defclass tab-bar (dirty-mixin)
+  ((tabs :initform nil :initarg :tabs :accessor tab-bar-tabs :type list)
+   (active :initform nil :initarg :active :accessor tab-bar-active)
+   (layout-node :initform (make-layout-node) :accessor tab-bar-layout-node)
+   (focusable :initform t :accessor tab-bar-focusable)))
+
+(defun make-tab-bar (&key tabs active)
+  (make-instance 'tab-bar :tabs (or tabs nil) :active active))
+
+(defun tab-bar-add (tb id title)
+  (setf (tab-bar-tabs tb) (nconc (tab-bar-tabs tb) (list (list :id id :title title))))
+  (unless (tab-bar-active tb) (setf (tab-bar-active tb) id)) id)
+
+(defmethod component-layout-node ((tb tab-bar)) (tab-bar-layout-node tb))
+
+(defun tab-bar-next (tb)
+  (let* ((tabs (tab-bar-tabs tb)) (current (tab-bar-active tb))
+         (ids (mapcar (lambda (tab) (getf tab :id)) tabs))
+         (pos (position current ids)))
+    (when pos (let ((next (nth (mod (1+ pos) (length ids)) ids)))
+                (setf (tab-bar-active tb) next) (mark-dirty tb)))))
+
+(defun tab-bar-prev (tb)
+  (let* ((tabs (tab-bar-tabs tb)) (current (tab-bar-active tb))
+         (ids (mapcar (lambda (tab) (getf tab :id)) tabs))
+         (pos (position current ids)))
+    (when pos (let ((prev (nth (mod (1- pos) (length ids)) ids)))
+                (setf (tab-bar-active tb) prev) (mark-dirty tb)))))
+
+(defun tab-bar-select (tb id) (setf (tab-bar-active tb) id) (mark-dirty tb))
+
+(defun tab-bar-handle-key (tb event)
+  (case (key-event-key event) (:left (tab-bar-prev tb) t) (:right (tab-bar-next tb) t) (t nil)))
+
+(defmethod render ((tb tab-bar) backend)
+  (let* ((ln (tab-bar-layout-node tb)) (y 0)
+         (w (if ln (layout-node-width ln) 80))
+         (active-id (tab-bar-active tb)) (tabs (tab-bar-tabs tb)) (x-pos 0))
+    (dolist (tab tabs)
+      (let* ((id (getf tab :id)) (title (getf tab :title))
+             (label (format nil " ~A " title)) (label-len (length label))
+             (is-active (eql id active-id))
+             (fg (if is-active :accent :text-muted))
+             (bg (if is-active :background-element nil)))
+        (when (>= (+ x-pos label-len 2) w)
+          (draw-text backend x-pos y "..." :text-muted nil) (return))
+        (draw-text backend x-pos y label fg bg)
+        (incf x-pos (+ label-len 2)))))
+  (values))

tests/input-tests.lisp

@@ -0,0 +1,269 @@
+(defpackage :cl-tui-input-test
+  (:use :cl :fiveam :cl-tui.backend :cl-tui.box :cl-tui.layout :cl-tui.input)
+  (:export #:run-tests))
+(in-package :cl-tui-input-test)
+
+(def-suite input-suite :description "Text input and keybinding tests")
+(in-suite input-suite)
+
+(defun run-tests ()
+  (let ((result (run 'input-suite)))
+    (fiveam:explain! result)
+    (uiop:quit 0)))
+
+;; ── Key Event Tests ─────────────────────────────────────────────
+
+(test key-event-construction
+  "A key-event can be created and queried."
+  (let ((e (make-key-event :key :a :ctrl t :alt nil)))
+    (is (eql (key-event-key e) :a))
+    (is-true (key-event-ctrl e))
+    (is-false (key-event-alt e))))
+
+(test key-event-defaults
+  "Fields default to NIL/nil."
+  (let ((e (make-key-event :key :space)))
+    (is (eql (key-event-key e) :space))
+    (is-false (key-event-ctrl e))
+    (is-false (key-event-alt e))
+    (is-false (key-event-shift e))))
+
+(test mouse-event-construction
+  "A mouse-event can be created and queried."
+  (let ((e (make-mouse-event :type :press :button :left :x 10 :y 5)))
+    (is (eql (mouse-event-type e) :press))
+    (is (eql (mouse-event-button e) :left))
+    (is (= (mouse-event-x e) 10))
+    (is (= (mouse-event-y e) 5))))
+
+;; ── TextInput Tests ─────────────────────────────────────────────
+
+(test text-input-empty
+  "A newly created text-input has empty value and cursor at 0."
+  (let ((in (make-text-input)))
+    (is (string= (text-input-value in) ""))
+    (is (= (text-input-cursor in) 0))))
+
+(test text-input-insert-char
+  "Inserting a character appends and moves cursor."
+  (let ((in (make-text-input)))
+    (handle-text-input in (make-key-event :key :a :code (char-code #\a)))
+    (is (string= (text-input-value in) "a"))
+    (is (= (text-input-cursor in) 1))))
+
+(test text-input-insert-multiple
+  "Inserting multiple characters works left to right."
+  (let ((in (make-text-input)))
+    (handle-text-input in (make-key-event :key :h :code (char-code #\h)))
+    (handle-text-input in (make-key-event :key :e :code (char-code #\e)))
+    (handle-text-input in (make-key-event :key :l :code (char-code #\l)))
+    (handle-text-input in (make-key-event :key :l :code (char-code #\l)))
+    (handle-text-input in (make-key-event :key :o :code (char-code #\o)))
+    (is (string= (text-input-value in) "hello"))
+    (is (= (text-input-cursor in) 5))))
+
+(test text-input-backspace
+  "Backspace removes the character before the cursor."
+  (let ((in (make-text-input :value "ab" :cursor 2)))
+    (handle-text-input in (make-key-event :key :backspace))
+    (is (string= (text-input-value in) "a"))
+    (is (= (text-input-cursor in) 1))))
+
+(test text-input-backspace-at-start
+  "Backspace at position 0 does nothing."
+  (let ((in (make-text-input :value "ab" :cursor 0)))
+    (handle-text-input in (make-key-event :key :backspace))
+    (is (string= (text-input-value in) "ab"))
+    (is (= (text-input-cursor in) 0))))
+
+(test text-input-delete
+  "Delete removes the character at the cursor."
+  (let ((in (make-text-input :value "abc" :cursor 1)))
+    (handle-text-input in (make-key-event :key :delete))
+    (is (string= (text-input-value in) "ac"))
+    (is (= (text-input-cursor in) 1))))
+
+(test text-input-cursor-left-right
+  "Cursor moves left and right."
+  (let ((in (make-text-input :value "ab" :cursor 2)))
+    (handle-text-input in (make-key-event :key :left))
+    (is (= (text-input-cursor in) 1))
+    (handle-text-input in (make-key-event :key :right))
+    (is (= (text-input-cursor in) 2))))
+
+(test text-input-cursor-bounds
+  "Cursor cannot move past start or end."
+  (let ((in (make-text-input :value "ab" :cursor 0)))
+    (handle-text-input in (make-key-event :key :left))
+    (is (= (text-input-cursor in) 0))
+    (setf (text-input-cursor in) 2)
+    (handle-text-input in (make-key-event :key :right))
+    (is (= (text-input-cursor in) 2))))
+
+(test text-input-home-end
+  "Home moves to start, End moves to end."
+  (let ((in (make-text-input :value "hello" :cursor 3)))
+    (handle-text-input in (make-key-event :key :home))
+    (is (= (text-input-cursor in) 0))
+    (handle-text-input in (make-key-event :key :end))
+    (is (= (text-input-cursor in) 5))))
+
+(test text-input-max-length
+  "Max-length prevents inserting beyond the limit."
+  (let ((in (make-text-input :max-length 3)))
+    (handle-text-input in (make-key-event :key :a :code (char-code #\a)))
+    (handle-text-input in (make-key-event :key :b :code (char-code #\b)))
+    (handle-text-input in (make-key-event :key :c :code (char-code #\c)))
+    (handle-text-input in (make-key-event :key :d :code (char-code #\d)))
+    (is (string= (text-input-value in) "abc"))))
+
+(test text-input-placeholder
+  "Placeholder is stored but does not affect value."
+  (let ((in (make-text-input :placeholder "Type here...")))
+    (is (string= (text-input-placeholder in) "Type here..."))
+    (is (string= (text-input-value in) ""))))
+
+(test text-input-on-submit
+  "On-submit callback fires on Enter."
+  (let ((result (list nil)))
+    (let ((in (make-text-input :value "hello"
+                               :on-submit (lambda (v) (setf (car result) v)))))
+      (handle-text-input in (make-key-event :key :enter))
+      (is (string= (car result) "hello")))))
+
+(test text-input-ctrl-a-e
+  "Ctrl+A moves to home, Ctrl+E moves to end."
+  (let ((in (make-text-input :value "abc" :cursor 2)))
+    (handle-text-input in (make-key-event :key :a :ctrl t))
+    (is (= (text-input-cursor in) 0))
+    (handle-text-input in (make-key-event :key :e :ctrl t))
+    (is (= (text-input-cursor in) 3))))
+
+(test text-input-insert-in-middle
+  "Inserting in the middle of text shifts rest right."
+  (let ((in (make-text-input :value "ab" :cursor 1)))
+    (handle-text-input in (make-key-event :key :x :code (char-code #\x)))
+    (is (string= (text-input-value in) "axb"))
+    (is (= (text-input-cursor in) 2))))
+
+(test text-input-dirty-on-insert
+  "Inserting marks the widget dirty."
+  (let ((in (make-text-input)))
+    (mark-clean in)
+    (handle-text-input in (make-key-event :key :a :code (char-code #\a)))
+    (is-true (dirty-p in))))
+
+;; ── Textarea Tests ──────────────────────────────────────────────
+
+(test textarea-empty
+  "New textarea has empty value and cursor at (0,0)."
+  (let ((a (make-textarea)))
+    (is (string= (textarea-value a) ""))
+    (is (= (textarea-cursor-row a) 0))
+    (is (= (textarea-cursor-col a) 0))))
+
+(test textarea-newline
+  "Enter inserts a newline."
+  (let ((a (make-textarea)))
+    (handle-textarea-input a (make-key-event :key :a :code (char-code #\a)))
+    (handle-textarea-input a (make-key-event :key :enter))
+    (handle-textarea-input a (make-key-event :key :b :code (char-code #\b)))
+    (is (string= (textarea-value a) "a
+b"))))
+
+(test textarea-cursor-up-down
+  "Cursor moves between lines maintaining column position."
+  (let ((a (make-textarea :value "abc
+de
+fghi")))
+    (setf (textarea-cursor-row a) 1)
+    (setf (textarea-cursor-col a) 1)
+    (handle-textarea-input a (make-key-event :key :up))
+    (is (= (textarea-cursor-row a) 0))
+    (is (= (textarea-cursor-col a) 1))
+    (handle-textarea-input a (make-key-event :key :down))
+    (is (= (textarea-cursor-row a) 1))
+    (is (= (textarea-cursor-col a) 1))))
+
+(test textarea-cursor-up-down-bounds
+  "Cursor cannot move past first or last line."
+  (let ((a (make-textarea :value "a
+b")))
+    (handle-textarea-input a (make-key-event :key :up))
+    (is (= (textarea-cursor-row a) 0))
+    (setf (textarea-cursor-row a) 1)
+    (handle-textarea-input a (make-key-event :key :down))
+    (is (= (textarea-cursor-row a) 1))))
+
+(test textarea-backspace-joins-lines
+  "Backspace at start of a line joins with previous."
+  (let ((a (make-textarea :value "hello
+world")))
+    (setf (textarea-cursor-row a) 1)
+    (setf (textarea-cursor-col a) 0)
+    (handle-textarea-input a (make-key-event :key :backspace))
+    (is (string= (textarea-value a) "helloworld"))))
+
+(test textarea-undo
+  "Ctrl+Z undoes the last edit."
+  (let ((a (make-textarea)))
+    (handle-textarea-input a (make-key-event :key :a :code (char-code #\a)))
+    (handle-textarea-input a (make-key-event :key :z :ctrl t))
+    (is (string= (textarea-value a) ""))))
+
+(test textarea-undo-redo
+  "Ctrl+Y redoes an undone edit."
+  (let ((a (make-textarea)))
+    (handle-textarea-input a (make-key-event :key :a :code (char-code #\a)))
+    (handle-textarea-input a (make-key-event :key :z :ctrl t))
+    (handle-textarea-input a (make-key-event :key :y :ctrl t))
+    (is (string= (textarea-value a) "a"))))
+
+;; ── Keybinding Tests ────────────────────────────────────────────
+
+(test keymap-simple
+  "A keymap dispatches to its handler on matching event."
+  (let ((called nil))
+    (setf (gethash :global *keymaps*)
+          (make-keymap :name :global
+                       :bindings `((:ctrl+p . ,(lambda (e)
+                                                 (declare (ignore e))
+                                                 (setf called t))))))
+    (is-true (dispatch-key-event (make-key-event :key :p :ctrl t)))
+    (is-true called)))
+
+(test keymap-no-match
+  "Non-matching event returns nil."
+  (let ((called nil))
+    (setf (gethash :global *keymaps*)
+          (make-keymap :name :global
+                       :bindings `((:ctrl+p . ,(lambda (e)
+                                                 (declare (ignore e))
+                                                 (setf called t))))))
+    (is-false (dispatch-key-event (make-key-event :key :a)))
+    (is-false called)))
+
+(test keymap-fallback
+  "Event not in local falls through to global."
+  (let ((global-called nil))
+    (setf (gethash :global *keymaps*)
+          (make-keymap :name :global
+                       :bindings `((:ctrl+q . ,(lambda (e)
+                                                 (declare (ignore e))
+                                                 (setf global-called t))))))
+    (dispatch-key-event (make-key-event :key :q :ctrl t))
+    (is-true global-called)))
+
+(test key-spec-simple
+  "Keyword key-spec matches key+ctrl."
+  (is-true (key-match-p :ctrl+p (make-key-event :key :p :ctrl t)))
+  (is-false (key-match-p :ctrl+p (make-key-event :key :a :ctrl t)))
+  (is-false (key-match-p :ctrl+p (make-key-event :key :p))))
+
+(test defkeymap-macro
+  "defkeymap macro registers a keymap."
+  (let ((called nil))
+    (eval `(defkeymap :global
+             (:ctrl+q ,(lambda (e) (declare (ignore e)) (setf called t)))))
+    (dispatch-key-event (make-key-event :key :q :ctrl t))
+    (is-true called)))

tests/scrollbox-tabbar-tests.lisp

@@ -0,0 +1,128 @@
+(defpackage :cl-tui-scrollbox-test
+  (:use :cl :fiveam :cl-tui.backend :cl-tui.box :cl-tui.layout :cl-tui.input :cl-tui.container)
+  (:export #:run-tests))
+(in-package #:cl-tui-scrollbox-test)
+
+(def-suite scrollbox-suite :description "ScrollBox + TabBar tests")
+(in-suite scrollbox-suite)
+
+(defun run-tests ()
+  (let ((result (run 'scrollbox-suite)))
+    (fiveam:explain! result)
+    (uiop:quit 0)))
+
+;; ── ScrollBox Tests ─────────────────────────────────────────────
+
+(test scrollbox-creates
+  "A ScrollBox can be created with defaults."
+  (let ((sb (make-scroll-box)))
+    (is (typep sb 'scroll-box))
+    (is (= (scroll-box-scroll-y sb) 0))
+    (is (= (scroll-box-scroll-x sb) 0))
+    (is-false (scroll-box-children sb))))
+
+(test scrollbox-with-children
+  "A ScrollBox can have children."
+  (let ((sb (make-scroll-box :children (list (make-text "hello")))))
+    (is (= (length (scroll-box-children sb)) 1))))
+
+(test scrollbox-scroll-by
+  "ScrollBy adjusts offset clamped to valid range."
+  (let ((sb (make-scroll-box :scroll-y 0)))
+    (scroll-by sb 5 0)
+    (is (>= (scroll-box-scroll-y sb) 0))))
+
+(test scrollbox-component-children
+  "Component protocol: children are accessible."
+  (let* ((child (make-text "hello"))
+         (sb (make-scroll-box :children (list child))))
+    (is (eql (first (component-children sb)) child))))
+
+(test scrollbox-render-noop
+  "Rendering a ScrollBox with no children does not error."
+  (let* ((stream (make-string-output-stream))
+         (backend (make-simple-backend :output-stream stream))
+         (sb (make-scroll-box)))
+    (render sb backend)
+    (is-true t)))
+
+;; ── TabBar Tests ────────────────────────────────────────────────
+
+(test tabbar-creates
+  "A TabBar can be created with defaults."
+  (let ((tb (make-tab-bar)))
+    (is (typep tb 'tab-bar))
+    (is-false (tab-bar-active tb))
+    (is-false (tab-bar-tabs tb))))
+
+(test tabbar-add-tab
+  "Adding a tab returns the id and updates tabs."
+  (let ((tb (make-tab-bar)))
+    (let ((id (tab-bar-add tb :tab1 "Tab One")))
+      (is (eql id :tab1))
+      (is (= (length (tab-bar-tabs tb)) 1))
+      (is (string= (getf (first (tab-bar-tabs tb)) :title) "Tab One")))))
+
+(test tabbar-active-tab
+  "Setting active tab works."
+  (let ((tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (setf (tab-bar-active tb) :tab2)
+    (is (eql (tab-bar-active tb) :tab2))))
+
+(test tabbar-render-noop
+  "Rendering a TabBar does not error."
+  (let* ((stream (make-string-output-stream))
+         (backend (make-simple-backend :output-stream stream))
+         (tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (setf (tab-bar-active tb) :tab1)
+    (render tb backend)
+    (is-true t)))
+
+(test tabbar-next-prev
+  "TabBar next/prev wraps around through tabs."
+  (let ((tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (tab-bar-add tb :tab3 "Three")
+    (is (eql (tab-bar-active tb) :tab1))
+    (tab-bar-next tb)
+    (is (eql (tab-bar-active tb) :tab2))
+    (tab-bar-next tb)
+    (is (eql (tab-bar-active tb) :tab3))
+    (tab-bar-next tb)
+    (is (eql (tab-bar-active tb) :tab1) "wrap around past last")
+    (tab-bar-prev tb)
+    (is (eql (tab-bar-active tb) :tab3) "wrap around past first")))
+
+(test tabbar-select
+  "TabBar select activates the specified tab."
+  (let ((tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (tab-bar-select tb :tab2)
+    (is (eql (tab-bar-active tb) :tab2))))
+
+(test tabbar-handle-key
+  "TabBar handle-key dispatches left/right."
+  (let ((tb (make-tab-bar)))
+    (tab-bar-add tb :tab1 "One")
+    (tab-bar-add tb :tab2 "Two")
+    (setf (tab-bar-active tb) :tab1)
+    (tab-bar-handle-key tb (make-key-event :key :right))
+    (is (eql (tab-bar-active tb) :tab2))
+    (tab-bar-handle-key tb (make-key-event :key :left))
+    (is (eql (tab-bar-active tb) :tab1))))
+
+(test scrollbox-scroll-clamp
+  "ScrollBox clamp prevents scrolling past bounds."
+  (let ((sb (make-scroll-box :scroll-y 5 :scroll-x 3)))
+    (setf (scroll-box-scroll-y sb) -1)
+    (clamp-scroll sb)
+    (is (= (scroll-box-scroll-y sb) 0) "clamps below 0")
+    (setf (scroll-box-scroll-y sb) 1000000)
+    (clamp-scroll sb)
+    (is (= (scroll-box-scroll-y sb) 0) "clamps above max (no children = 0 content)")))