fix(newos4): mode layout constraints, capture() arg split, suppress classic welcome modal

- #ui-root is a flex column (it was display:block, so every mode's flex:1 was inert and the
  terminal collapsed to 0px while the composer sat at the bottom of a 4600px flow)
- overflow:clip on #ui-root and body: overflow:hidden is still a scroll container, and the
  terminal's scrollIntoView() on new output scrolled the mode's own chrome off-screen
- terminal min-height 100px: in the tabbed/panel modes its grid parent is not a flex parent
- api.capture() split arguments itself; term._parseArgs does not exist, so every panel showed
  'unavailable: term._parseArgs is not a function'
- the classic Let's Get Started modal is suppressed in non-classic modes: it covered easy's cards

1 files changed, 26 insertions, 5 deletions

diff --git a/modules/core/module-uishell.js b/modules/core/module-uishell.js
index 63a1437..ac14b20 100644
--- a/modules/core/module-uishell.js
+++ b/modules/core/module-uishell.js
@@ -306,13 +306,31 @@ class UIShellModule {
         const st = document.createElement('style');
         st.id = 'wx11-ui-base-css';
         st.textContent = [
-            '#ui-root{position:fixed;inset:0;display:none;overflow:hidden;z-index:40;background:var(--bg-color);color:var(--text-color)}',
-            'body[data-ui-mode]:not([data-ui-mode="classic"]) #ui-root{display:block}',
+            // clip, not hidden: `overflow:hidden` still creates a scroll container, and the terminal's
+            // scrollIntoView() on new output scrolled #ui-root by 464px — the title, the action cards
+            // and the composer all left the screen (measured 2026-11-07). `clip` cannot be scrolled.
+            '#ui-root{position:fixed;inset:0;display:none;overflow:clip;z-index:40;background:var(--bg-color);color:var(--text-color)}',
+            // flex column, not block: every mode is a vertical stack (chrome / content / composer /
+            // footer) and a block container makes each child's `flex:1 1 auto` inert — the terminal
+            // collapsed to 0px and the composer sat at the very bottom of a 4 600px flow.
+            'body[data-ui-mode]:not([data-ui-mode="classic"]) #ui-root{display:flex;flex-direction:column;height:100%}',
+            '#ui-root > *{min-width:0;min-height:0}',
+            // A non-classic mode owns the viewport: the page itself must not scroll, or terminal
+            // output drags the action cards off-screen and the composer never comes back.
+            'body[data-ui-mode]:not([data-ui-mode="classic"]){overflow:clip}',
+            'body[data-ui-mode]:not([data-ui-mode="classic"]) #ui-root{overflow:clip}',
             'body[data-ui-mode]:not([data-ui-mode="classic"]) #cmd-cards{display:none!important}',
+            // A mode IS the onboarding: six cards behind the classic "Let's Get Started" modal is two
+            // competing first-run prompts, and the modal covered the easy mode's action cards.
+            'body[data-ui-mode]:not([data-ui-mode="classic"]) #welcome-modal{display:none!important}',
             'body[data-ui-mode]:not([data-ui-mode="classic"]) #ui-root{padding-bottom:34px}',
             // The stock containers are flex children of <body>; inside a pane they must be able to
             // shrink, or every mode overflows vertically and the input scrolls off-screen.
-            '#ui-root #terminal-container{flex:1 1 auto;min-height:0;height:auto;overflow-y:auto;padding:0}',
+            // basis 0, not auto: with `auto` the terminal takes its 4 600px content height and pushes
+            // every sibling out of the viewport instead of scrolling inside its own pane.
+            // min-height 100px, not 0: in the tabbed/panel modes the terminal sits inside a grid cell
+            // that is not a flex parent, so `flex:1 1 0` resolves to 0 and the output strip vanished.
+            '#ui-root #terminal-container{flex:1 1 0;min-height:100px;height:0;overflow-y:auto;padding:0}',
             '#ui-root #input-area{flex:0 0 auto}',
             '#ui-root #status-bar{flex:0 0 auto}',
             '#ui-foot{position:absolute;left:0;right:0;bottom:0;height:34px;display:flex;align-items:center;',
@@ -370,10 +388,13 @@ class UIShellModule {
             exec: (line) => term.executeCommand(String(line)),
             // shell-authored fixed strings only → capturePipeOutput (no security gate)
             capture: (line) => {
-                const parts = term._parseArgs(String(line).trim());
+                // Do NOT use terminal._parseArgs — it does not exist on the terminal instance; every
+                // panel rendered "unavailable: term._parseArgs is not a function" (measured 2026-11-07).
+                const raw = String(line).trim();
+                const parts = raw.match(/(?:[^\s"']+|"[^"]*"|'[^']*')+/g) || [];
                 const cmd = parts[0];
                 if (!cmd) return Promise.resolve('');
-                return term.capturePipeOutput(cmd, parts.slice(1), String(line));
+                return term.capturePipeOutput(cmd, parts.slice(1), raw);
             },
             fs: term.fs,
             el: (tag, props, kids) => {