feat(web): open tasks/sessions as floating windows with independent live chat

Clicking a task now opens it as a wmkit floating window (like entity
windows already do) instead of navigating away from wherever you were.
Several task windows can be open and actively streaming at once, each
fully independent — no "which one's on screen" guard needed, since
each window owns its own store bundle:

- chat.ts: chatFor(sessionId)/loadSessionChat/sendSessionMessage give
  each window its own messages/streaming/connectionState, alongside
  the existing singleton path the main Chat page still uses unchanged.
- workspace.ts: same split for plan/questions/touched/health-diffs
  (workspaceFor/startSessionWorkspace), each with its own live-event
  watermark since several windows can watch the same event stream.
- activity.ts: activityLogFor(sessionId) mirrors the global derivation.

SessionGraph.svelte, OperatorQuestion.svelte, and ActivityTimeline.svelte
were converted from store-importing to prop-driven (matching the new
ChatThread.svelte, extracted from Chat.svelte's transcript/input so both
the main page and task windows share one implementation instead of
duplicating markup/styling) so each can render either the global
"current session" or a specific window's session.

Also: minimized-window taskbar chips now cap at a max width with
middle-ellipsis truncation instead of growing unbounded, and the
window header's title/action-button row is fixed to genuinely match
heights (not just share a center point) for more robust alignment.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

web/src/lib/components/ChatThread.svelte

@@ -0,0 +1,377 @@
+<script lang="ts">
+  // Pure prop-driven transcript + input — no store imports. Both the main
+  // Chat page (singleton "current session" stores) and a floating task
+  // window (its own per-session store bundle from chat.ts's chatFor) render
+  // through this, so the message-bubble/markdown styling lives in one place
+  // instead of being copy-pasted between the two.
+  import { activityLog } from '$lib/stores/activity'
+  import AgentIndicator from '$lib/components/AgentIndicator.svelte'
+  import { Button } from '$lib/components/ui/button'
+  import { Textarea } from '$lib/components/ui/textarea'
+  import ArrowUpIcon from '@lucide/svelte/icons/arrow-up'
+  import RefreshCwIcon from '@lucide/svelte/icons/refresh-cw'
+  import SquareIcon from '@lucide/svelte/icons/square'
+  import { marked } from 'marked'
+  import DOMPurify from 'dompurify'
+  import type { ChatMessage } from '$lib/stores/chat'
+
+  let {
+    messages,
+    streaming,
+    connectionState,
+    error = null,
+    chatErrors = [],
+    onSend,
+    onCancel,
+    onReconnect,
+    onDismissError,
+    suggestions = []
+  }: {
+    messages: ChatMessage[]
+    streaming: boolean
+    connectionState: 'connected' | 'disconnected' | 'reconnecting'
+    error?: string | null
+    chatErrors?: { id: string; message: string; action?: string }[]
+    onSend: (text: string) => void
+    onCancel: () => void
+    onReconnect: () => void
+    onDismissError: (id: string) => void
+    suggestions?: string[]
+  } = $props()
+
+  let input = $state('')
+  let messagesEnd = $state<HTMLDivElement | null>(null)
+  let scrolledUp = $state(false)
+  let container = $state<HTMLDivElement | null>(null)
+
+  function isNearBottom(): boolean {
+    if (!container) return true
+    const { scrollTop, scrollHeight, clientHeight } = container
+    return scrollHeight - scrollTop - clientHeight < 80
+  }
+
+  function onScroll() {
+    scrolledUp = !isNearBottom()
+  }
+
+  // Auto-scroll to bottom on new messages — unless user scrolled up to read.
+  $effect(() => {
+    void messages
+    if (streaming || !scrolledUp) {
+      setTimeout(() => messagesEnd?.scrollIntoView({ behavior: 'smooth' }), 50)
+    }
+  })
+
+  function render(text: string): string {
+    return DOMPurify.sanitize(marked.parse(text, { async: false }) as string)
+  }
+
+  function submit() {
+    const text = input.trim()
+    if (!text || streaming) return
+    input = ''
+    scrolledUp = false
+    onSend(text)
+  }
+
+  function handleKeydown(e: KeyboardEvent) {
+    if (e.key === 'Enter' && !e.shiftKey) {
+      e.preventDefault()
+      submit()
+    }
+  }
+
+  function ask(q: string) {
+    if (streaming) return
+    onSend(q)
+  }
+</script>
+
+<div class="flex min-h-0 min-w-0 flex-1 flex-col">
+  <div class="min-h-0 flex-1 overflow-y-auto" bind:this={container} onscroll={onScroll}>
+    <div class="mx-auto flex max-w-3xl flex-col gap-5 p-4">
+      {#if messages.length === 0}
+        <div class="flex flex-col items-center gap-6 pt-24 text-center">
+          <div>
+            <h2 class="text-xl font-semibold">Nomos</h2>
+            <p class="mt-1 text-sm text-muted-foreground">Your resident operator. Ask about the fleet, or tell it to act.</p>
+          </div>
+          {#if suggestions.length}
+            <div class="grid w-full max-w-md grid-cols-1 gap-2 sm:grid-cols-2">
+              {#each suggestions as q}
+                <Button variant="outline" size="sm" class="h-auto justify-start whitespace-normal py-2 text-left text-xs" onclick={() => ask(q)}>
+                  {q}
+                </Button>
+              {/each}
+            </div>
+          {/if}
+        </div>
+      {/if}
+
+      {#each messages as msg (msg.id)}
+        <div class="flex flex-col gap-1.5 {msg.role === 'user' ? 'items-end' : 'items-start'}">
+          {#if msg.role === 'user'}
+            <div class="max-w-[85%] rounded-2xl rounded-br-sm bg-primary px-4 py-2.5 text-sm text-primary-foreground whitespace-pre-wrap user-msg">{msg.text}</div>
+          {:else}
+            <div class="flex w-full flex-col gap-2">
+              {#if msg.text}
+                <div class="prose-chat max-w-none text-sm leading-relaxed assistant-msg">
+                  <!-- eslint-disable-next-line svelte/no-at-html-tags — sanitized via DOMPurify -->
+                  {@html render(msg.text)}
+                </div>
+              {/if}
+            </div>
+          {/if}
+        </div>
+      {/each}
+      <AgentIndicator
+        active={streaming || $activityLog.some((e) => e.status === 'running')}
+        lastActivity={$activityLog.find((e) => e.status === 'running') ?? null}
+        {error}
+      />
+      <div bind:this={messagesEnd}></div>
+    </div>
+  </div>
+
+  {#if connectionState === 'disconnected'}
+    <div class="mx-auto w-full max-w-3xl px-4">
+      <div class="mb-2 flex items-center gap-2 rounded-md border border-warning/50 bg-warning/10 px-3 py-2 text-xs">
+        <RefreshCwIcon class="size-3 shrink-0" aria-hidden="true" />
+        <span class="text-warning-foreground flex-1">Agent connection lost. The task may still be running.</span>
+        <Button size="xs" variant="outline" class="h-6 text-[11px]" onclick={onReconnect}>Reconnect</Button>
+      </div>
+    </div>
+  {:else if connectionState === 'reconnecting'}
+    <div class="mx-auto w-full max-w-3xl px-4">
+      <div class="mb-2 flex items-center gap-2 rounded-md border bg-muted/50 px-3 py-2 text-xs">
+        <RefreshCwIcon class="size-3 shrink-0 animate-spin text-muted-foreground" aria-hidden="true" />
+        <span class="text-muted-foreground flex-1">Reconnecting to agent…</span>
+      </div>
+    </div>
+  {/if}
+
+  {#if error}
+    <div class="mx-auto w-full max-w-3xl px-4">
+      <div class="mb-2 rounded-md border border-destructive/50 bg-destructive/10 px-3 py-2 text-xs text-destructive">
+        {error}
+      </div>
+    </div>
+  {/if}
+
+  {#each chatErrors as err (err.id)}
+    <div class="mx-auto w-full max-w-3xl px-4">
+      <div class="mb-2 flex items-center gap-2 rounded-md border border-destructive/30 bg-destructive/5 px-3 py-2 text-xs text-destructive">
+        <span class="flex-1">{err.message}</span>
+        {#if err.action}
+          <Button size="xs" variant="ghost" class="h-6 text-[11px]" onclick={() => onDismissError(err.id)}>{err.action}</Button>
+        {/if}
+        <button class="ml-1 text-muted-foreground hover:text-foreground" onclick={() => onDismissError(err.id)} aria-label="Dismiss">×</button>
+      </div>
+    </div>
+  {/each}
+
+  <div class="border-t bg-card/50 p-3 input-ornament relative">
+    <form
+      class="mx-auto flex max-w-3xl items-end gap-2"
+      onsubmit={(e) => {
+        e.preventDefault()
+        submit()
+      }}
+    >
+      <Textarea
+        bind:value={input}
+        onkeydown={handleKeydown}
+        placeholder="Ask Nomos anything…"
+        rows={2}
+        class="max-h-40 min-h-0 resize-none"
+        disabled={streaming}
+      />
+      {#if streaming}
+        <Button type="button" size="icon" variant="destructive" onclick={onCancel} aria-label="Stop">
+          <SquareIcon />
+        </Button>
+      {:else}
+        <Button type="submit" size="icon" disabled={!input.trim()} aria-label="Send">
+          <ArrowUpIcon />
+        </Button>
+      {/if}
+    </form>
+  </div>
+</div>
+
+<style>
+  /* ── Art Nouveau chat styling ── */
+
+  /* Assistant message wrapper */
+  .assistant-msg {
+    position: relative;
+  }
+
+  /* User message — soft terracotta bubble, gentle lift */
+  .user-msg {
+    box-shadow: 0 1px 8px -4px var(--primary);
+  }
+
+  /* Prose overrides */
+  .prose-chat :global(p) {
+    margin: 0 0 0.5rem;
+  }
+  .prose-chat :global(p:last-child) {
+    margin-bottom: 0;
+  }
+
+  .prose-chat :global(ul),
+  .prose-chat :global(ol) {
+    margin: 0 0 0.5rem;
+    padding-left: 1.25rem;
+  }
+  .prose-chat :global(ul) {
+    list-style-type: disc;
+  }
+  .prose-chat :global(ol) {
+    list-style-type: decimal;
+  }
+  .prose-chat :global(li) {
+    margin-bottom: 0.125rem;
+    padding-left: 0.25rem;
+  }
+  .prose-chat :global(li::marker) {
+    color: var(--primary);
+  }
+
+  .prose-chat :global(code) {
+    background: var(--muted);
+    border: 1px solid var(--border);
+    border-radius: 4px;
+    padding: 0.15em 0.4em;
+    font-family: var(--font-mono);
+    font-size: 0.85em;
+    color: var(--primary);
+  }
+
+  .prose-chat :global(pre) {
+    background: var(--muted);
+    border: 1px solid var(--border);
+    border-radius: 8px;
+    padding: 0.75rem 0.875rem;
+    overflow-x: auto;
+    margin: 0 0 0.5rem;
+    position: relative;
+  }
+  .prose-chat :global(pre)::before {
+    content: '';
+    position: absolute;
+    top: 0;
+    left: 0;
+    right: 0;
+    height: 1px;
+    background: linear-gradient(to right, transparent, var(--primary), transparent);
+    opacity: 0.4;
+  }
+  .prose-chat :global(pre code) {
+    background: none;
+    padding: 0;
+    font-size: 0.8125rem;
+    color: inherit;
+    border: none;
+  }
+
+  /* Section headings — serif (Inknut) with a short accent rule. Extra top
+     margin separates sections; the first heading in a message doesn't. */
+  .prose-chat :global(h1),
+  .prose-chat :global(h2),
+  .prose-chat :global(h3) {
+    font-weight: 600;
+    margin: 1.15rem 0 0.4rem;
+    font-size: 1.03em;
+    letter-spacing: 0.01em;
+    position: relative;
+    display: inline-block;
+  }
+  .prose-chat :global(> h1:first-child),
+  .prose-chat :global(> h2:first-child),
+  .prose-chat :global(> h3:first-child) {
+    margin-top: 0;
+  }
+  .prose-chat :global(h1)::after,
+  .prose-chat :global(h2)::after,
+  .prose-chat :global(h3)::after {
+    content: '';
+    display: block;
+    width: 2.5rem;
+    height: 2px;
+    margin-top: 4px;
+    border-radius: 1px;
+    background: linear-gradient(to right, var(--primary), transparent);
+    opacity: 0.55;
+  }
+
+  .prose-chat :global(table) {
+    border-collapse: collapse;
+    margin: 0 0 0.5rem;
+    font-size: 0.8125rem;
+  }
+  .prose-chat :global(th) {
+    background: var(--muted);
+    font-weight: 600;
+  }
+  .prose-chat :global(th),
+  .prose-chat :global(td) {
+    border: 1px solid var(--border);
+    padding: 0.3rem 0.6rem;
+    text-align: left;
+  }
+
+  .prose-chat :global(blockquote) {
+    border-left: 3px solid var(--primary);
+    padding-left: 0.75rem;
+    color: var(--muted-foreground);
+    margin: 0 0 0.5rem;
+    font-style: italic;
+    position: relative;
+  }
+  .prose-chat :global(blockquote)::before {
+    content: '“';
+    position: absolute;
+    left: -0.15rem;
+    top: -0.35rem;
+    font-size: 1.5rem;
+    color: var(--primary);
+    opacity: 0.6;
+    font-style: normal;
+    line-height: 1;
+  }
+
+  .prose-chat :global(hr) {
+    border: none;
+    height: 1px;
+    margin: 0.75rem 0;
+    background: linear-gradient(to right, transparent, var(--border) 20%, var(--border) 80%, transparent);
+  }
+
+  /* Bold is emphasis, not color — dark weight reads cleanly and lets the
+     terracotta accent stay meaningful (code, headings, links). */
+  .prose-chat :global(strong) {
+    color: var(--foreground);
+    font-weight: 600;
+  }
+
+  .prose-chat :global(a) {
+    color: var(--primary);
+    text-decoration: underline;
+    text-decoration-style: dotted;
+    text-underline-offset: 2px;
+  }
+
+  /* Input area ornament */
+  .input-ornament::before {
+    content: '';
+    position: absolute;
+    top: 0;
+    left: 2rem;
+    right: 2rem;
+    height: 1px;
+    background: linear-gradient(to right, transparent, var(--primary), transparent);
+    opacity: 0.3;
+  }
+</style>