feat(web+nomos): fix chat streaming reactivity, unified activity timeline, tool cards in chat

- fix(web): Svelte 5 identity-based reactivity broke text_delta streaming —
  immutable message objects in all three chat handlers so text streams live
- feat(web): streaming cursor + inline status indicator merged into message flow
- feat(web): expandable inline tool call cards in chat thread
- feat(web): merge Plan + Event log into one backbone Activity timeline —
  filled status nodes, branch stubs, auto-scroll follow mode, per-session
  activityLog, compact for the rail
- fix(nomos): add X-Accel-Buffering:no to /chat SSE (proxy buffering)
- fix(nomos): plan step auto-close SQL param bug (store.go)
- polish: timestamps, role labels, code copy button, table overflow, min
  window size, delete AgentIndicator/ActivityTimeline dead code

plans/2026-07-21-chat-full-polish.md

@@ -0,0 +1,79 @@
+# 2026-07-21 Chat window full polish
+
+## Context
+
+After fixing the streaming reactivity bug and merging the double thinking
+indicator, the chat window still has structural UX gaps: no streaming
+affordance while text flows, tools never rendered inline, no timestamps,
+no code copy, cross-session store leaks in floating windows, and minor
+overflow/style holes.
+
+## Decisions
+
+| Question | Answer |
+|---|---|
+| Streaming feel | Typing cursor (blinking ▍) + inline indicator |
+| Tool calls | Expandable inline tool cards in message flow |
+| Empty state | Minimal — title + tagline, no suggestions |
+| Dark theme | Keep neutral (skip) |
+| Scope | Full polish — everything |
+
+## Changes
+
+### P0.1 Streaming cursor
+- **File:** `web/src/lib/components/ChatThread.svelte`
+- Add a blinking block-cursor (▍) appended after rendered markdown when
+  `streaming` is true and the last assistant message has text.
+- Keep the inline spinner + activity label for the empty-text state.
+- CSS: `@keyframes` blink, `0.8s` cycle, `primary` color, `inline-block`.
+
+### P0.2 Tool call cards
+- **New:** `web/src/lib/components/ToolCallCard.svelte`
+- **Modify:** `ChatThread.svelte`
+- Render `msg.tools` as collapsible cards between text blocks.
+- Collapsed: tool icon + name + status (running/done/error).
+- Expanded: pretty-printed args + result/error in `pre` blocks.
+- Keep it minimal — one card per tool call, no grouping.
+- Wire `pendingApprovals` from `msg.pendingApprovals` as approval
+  cards below the tool list.
+
+### P1.3 Timestamps + role labels
+- **Modify:** `ChatThread.svelte`, `ChatMessage` interface
+- Add `created_at?: string` to `ChatMessage` (populated from `Message.created_at`).
+- Show small muted timestamp (HH:MM) on hover or inline next to role label.
+- Add tiny "You" / "Nomos" labels above bubbles (subtle, muted).
+
+### P1.4 Code copy button
+- **Modify:** `ChatThread.svelte` prose styles
+- Wrap `pre` blocks in a relative container; add a copy button
+  (clipboard icon, top-right, opacity-0 → visible on hover).
+- Use `navigator.clipboard.writeText`.
+
+### P1.5 Table overflow + user bubble fix
+- **Modify:** `ChatThread.svelte` prose styles
+- Wrap tables in `overflow-x-auto` container.
+- Add `overflow-wrap: break-word` to user bubbles.
+
+### P2.6 Cross-session fixes
+- **Modify:** `web/src/lib/stores/chat.ts`, `SessionChatWindow.svelte`
+- `chatErrors`: keep global for now (session-scoped errors are rare
+  and the dismiss is manual anyway).
+- `activityLog`: **per-session** — the store in `activity.ts` already
+  derives from messages; make `computeActivityLog` session-scoped
+  so each floating window only sees its own activity.
+
+### P2.7 Min window size
+- **Modify:** `web/src/lib/stores/windows.ts` (openTaskWindow)
+- Add `minWidth: 600, minHeight: 400` to chat window open call.
+
+### P2.8 Cleanup
+- Delete `web/src/lib/components/AgentIndicator.svelte` (dead code).
+- Update stale comments in `SessionChatWindow.svelte` and
+  `TaskContextPanel.svelte` that reference a "main Chat page."
+- Fix prose heading hierarchy: h1 = 1.15em, h2 = 1.1em, h3 = 1.05em.
+
+## Verification
+
+- `npx eslint` on all changed files
+- `go vet ./cmd/nomos/...`
+- `go build -o /dev/null ./cmd/nomos/...`