feat(web): port chat UI — model selector, keybindings, thinking display, styled header

apps/web/src/components/chat/chat-input.tsx

@@ -1,52 +1,192 @@
 'use client';
 
-import { useRef, useState } from 'react';
+import { useEffect, useMemo, useRef, useState } from 'react';
+import type { ModelInfo } from '@/lib/types';
 
 interface ChatInputProps {
-  onSend: (content: string) => void;
-  disabled?: boolean;
+  onSend: (content: string, options?: { modelId?: string }) => void;
+  onStop?: () => void;
+  isStreaming?: boolean;
+  models: ModelInfo[];
+  selectedModelId: string;
+  onModelChange: (modelId: string) => void;
+  onRequestEditLastMessage?: () => string | null;
 }
 
-export function ChatInput({ onSend, disabled }: ChatInputProps): React.ReactElement {
+const MAX_HEIGHT = 220;
+
+export function ChatInput({
+  onSend,
+  onStop,
+  isStreaming = false,
+  models,
+  selectedModelId,
+  onModelChange,
+  onRequestEditLastMessage,
+}: ChatInputProps): React.ReactElement {
   const [value, setValue] = useState('');
   const textareaRef = useRef<HTMLTextAreaElement>(null);
+  const selectedModel = useMemo(
+    () => models.find((model) => model.id === selectedModelId) ?? models[0],
+    [models, selectedModelId],
+  );
 
-  function handleSubmit(e: React.FormEvent): void {
-    e.preventDefault();
+  useEffect(() => {
+    const textarea = textareaRef.current;
+    if (!textarea) return;
+    textarea.style.height = 'auto';
+    textarea.style.height = `${Math.min(textarea.scrollHeight, MAX_HEIGHT)}px`;
+  }, [value]);
+
+  useEffect(() => {
+    function handleGlobalFocus(event: KeyboardEvent): void {
+      if (
+        (event.metaKey || event.ctrlKey) &&
+        (event.key === '/' || event.key.toLowerCase() === 'k')
+      ) {
+        const target = event.target as HTMLElement | null;
+        if (target?.closest('input, textarea, [contenteditable="true"]')) return;
+        event.preventDefault();
+        textareaRef.current?.focus();
+      }
+    }
+
+    document.addEventListener('keydown', handleGlobalFocus);
+    return () => document.removeEventListener('keydown', handleGlobalFocus);
+  }, []);
+
+  function handleSubmit(event: React.FormEvent): void {
+    event.preventDefault();
     const trimmed = value.trim();
-    if (!trimmed || disabled) return;
-    onSend(trimmed);
+    if (!trimmed || isStreaming) return;
+    onSend(trimmed, { modelId: selectedModel?.id });
     setValue('');
     textareaRef.current?.focus();
   }
 
-  function handleKeyDown(e: React.KeyboardEvent<HTMLTextAreaElement>): void {
-    if (e.key === 'Enter' && !e.shiftKey) {
-      e.preventDefault();
-      handleSubmit(e);
+  function handleKeyDown(event: React.KeyboardEvent<HTMLTextAreaElement>): void {
+    if (event.key === 'Enter' && (event.metaKey || event.ctrlKey)) {
+      event.preventDefault();
+      handleSubmit(event);
+      return;
+    }
+
+    if (event.key === 'ArrowUp' && value.length === 0 && onRequestEditLastMessage) {
+      const lastMessage = onRequestEditLastMessage();
+      if (lastMessage) {
+        event.preventDefault();
+        setValue(lastMessage);
+      }
     }
   }
 
+  const charCount = value.length;
+  const tokenEstimate = Math.ceil(charCount / 4);
+
   return (
-    <form onSubmit={handleSubmit} className="border-t border-surface-border bg-surface-card p-4">
-      <div className="flex items-end gap-3">
-        <textarea
-          ref={textareaRef}
-          value={value}
-          onChange={(e) => setValue(e.target.value)}
-          onKeyDown={handleKeyDown}
-          disabled={disabled}
-          rows={1}
-          placeholder="Type a message... (Enter to send, Shift+Enter for newline)"
-          className="max-h-32 min-h-[2.5rem] flex-1 resize-none rounded-lg border border-surface-border bg-surface-elevated px-3 py-2 text-sm text-text-primary placeholder:text-text-muted focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:opacity-50"
-        />
-        <button
-          type="submit"
-          disabled={disabled || !value.trim()}
-          className="rounded-lg bg-blue-600 px-4 py-2 text-sm font-medium text-white transition-colors hover:bg-blue-700 disabled:opacity-50"
-        >
-          Send
-        </button>
+    <form
+      onSubmit={handleSubmit}
+      className="border-t px-4 py-4 backdrop-blur-xl md:px-6"
+      style={{
+        backgroundColor: 'color-mix(in srgb, var(--color-surface) 88%, transparent)',
+        borderColor: 'var(--color-border)',
+      }}
+    >
+      <div
+        className="rounded-[28px] border p-3 shadow-[var(--shadow-ms-lg)]"
+        style={{
+          backgroundColor: 'var(--color-surface-2)',
+          borderColor: 'var(--color-border)',
+        }}
+      >
+        <div className="mb-3 flex flex-wrap items-center gap-3">
+          <label className="flex min-w-0 items-center gap-2 text-xs text-[var(--color-muted)]">
+            <span className="uppercase tracking-[0.18em]">Model</span>
+            <select
+              value={selectedModelId}
+              onChange={(event) => onModelChange(event.target.value)}
+              className="rounded-full border px-3 py-1.5 text-sm outline-none"
+              style={{
+                backgroundColor: 'var(--color-surface)',
+                borderColor: 'var(--color-border)',
+                color: 'var(--color-text)',
+              }}
+            >
+              {models.map((model) => (
+                <option key={`${model.provider}:${model.id}`} value={model.id}>
+                  {model.name} · {model.provider}
+                </option>
+              ))}
+            </select>
+          </label>
+          <div className="ml-auto hidden items-center gap-2 text-xs text-[var(--color-muted)] md:flex">
+            <span className="rounded-full border border-[var(--color-border)] px-2 py-1">
+              ⌘/ focus
+            </span>
+            <span className="rounded-full border border-[var(--color-border)] px-2 py-1">
+              ⌘K focus
+            </span>
+            <span className="rounded-full border border-[var(--color-border)] px-2 py-1">
+              ⌘↵ send
+            </span>
+          </div>
+        </div>
+
+        <div className="flex items-end gap-3">
+          <textarea
+            ref={textareaRef}
+            value={value}
+            onChange={(event) => setValue(event.target.value)}
+            onKeyDown={handleKeyDown}
+            disabled={isStreaming}
+            rows={1}
+            placeholder="Ask Mosaic something..."
+            className="min-h-[3.25rem] flex-1 resize-none bg-transparent px-1 py-2 text-sm outline-none placeholder:text-[var(--color-muted)] disabled:opacity-60"
+            style={{
+              color: 'var(--color-text)',
+              maxHeight: `${MAX_HEIGHT}px`,
+            }}
+          />
+
+          {isStreaming ? (
+            <button
+              type="button"
+              onClick={onStop}
+              className="inline-flex h-11 items-center gap-2 rounded-full border px-4 text-sm font-medium transition-colors"
+              style={{
+                backgroundColor: 'var(--color-surface)',
+                borderColor: 'var(--color-border)',
+                color: 'var(--color-text)',
+              }}
+            >
+              <span className="inline-block h-2.5 w-2.5 rounded-sm bg-[var(--color-danger)]" />
+              Stop
+            </button>
+          ) : (
+            <button
+              type="submit"
+              disabled={!value.trim()}
+              className="inline-flex h-11 items-center gap-2 rounded-full px-4 text-sm font-semibold text-white transition-all disabled:cursor-not-allowed disabled:opacity-45"
+              style={{ backgroundColor: 'var(--color-ms-blue-500)' }}
+            >
+              <span>Send</span>
+              <span aria-hidden="true">↗</span>
+            </button>
+          )}
+        </div>
+
+        <div className="mt-3 flex flex-wrap items-center gap-2 text-xs text-[var(--color-muted)]">
+          <span>{charCount.toLocaleString()} chars</span>
+          <span>·</span>
+          <span>~{tokenEstimate.toLocaleString()} tokens</span>
+          {selectedModel ? (
+            <>
+              <span>·</span>
+              <span>{selectedModel.reasoning ? 'Reasoning on' : 'Fast response'}</span>
+            </>
+          ) : null}
+          <span className="ml-auto">Shift+Enter newline · Arrow ↑ edit last</span>
+        </div>
       </div>
     </form>
   );