Add ws chat UI

.gitignore

@@ -42,6 +42,9 @@ test_https.zig
 test_ws.py
 workspace/
 coverage/
+frontend/dist/
+frontend/node_modules/
+frontend/.astro/
 
 # Test artifacts
 scripts/

AGENTS.md

@@ -44,6 +44,7 @@ Entry: `src/main.zig`. Module root: `src/root.zig` (re-exports all modules as `@
 
 - **Logging:** All via `zero.App.logger` (Info/Err/Debug/Warn). Never use `std.log.*` or `std.debug.print` in app code.
 - **HTTP client:** `zul.http.Client` crashes on `deinit()` if pool has active connections. Workaround: `postJSONZul()` in `src/http_client.zig` sends `Connection: close` header. Do not remove this.
+- **WS upgrade + Vite proxy:** In dev, Vite's `/ws` proxy sometimes closes the connection mid-handshake. The server's `upgradeWebsocket` call returns `error.NotOpenForWriting` and the worker then calls `res.write()` on the now-dead FD. That second write hits Zig stdlib's `posix.sendmsg` which has `.BADF => unreachable` and panics the process. Mitigation: `wsUpgrade` in `src/channels/websocket.zig` catches the upgrade error and returns normally (no 500 response) so httpz's catch path doesn't re-write on a dead FD. Real fix for dev users: set `window.__EVA_WS_HOST__ = 'localhost:8765'` in the browser devtools to bypass the Vite WS proxy. In production (`EVA_SERVE_FRONTEND=true`) there's no Vite proxy and the issue does not occur.
 - **Telegram HTTPS:** Uses custom `TLSClient` (BearSSL-based), not `zul.http.Client` for polling. Only one `getUpdates` poller at a time — concurrent polls cause 409 conflicts.
 - **LLM responses:** Non-streaming only (`stream: false`). SSE streaming disabled due to Zig 0.15.2 `std.json.Scanner` buffer sensitivity.
 - **Allocators:** `GeneralPurposeAllocator` for long-lived structs (SessionManager, MessageBus). `ArenaAllocator` for short-lived parsing tasks only.

Makefile

@@ -1,5 +1,5 @@
 usage:
-	ps -p $(pgrep -d',' basic) -o %cpu,%mem
+	ps -p $(pgrep -d',' eva) -o %cpu,%mem
 
 trace:
 	strace -c zig build eva > /dev/null

frontend/README.md

@@ -0,0 +1,152 @@
+# Eva Frontend
+
+Astro 4 + Tailwind 3 single-page app served as static files. ~144 KB
+total (96 KB self-hosted woff2, 28 KB JS, 16 KB CSS, 4 KB HTML).
+
+## Quick start
+
+```bash
+# One-time: install deps
+npm install
+
+# Dev server (port 4321, proxies /api and /ws to :8765)
+npm run dev
+
+# Production build (outputs to dist/)
+npm run build
+
+# Preview the built bundle locally
+npm run preview
+
+# Type-check (Astro + TS)
+npx astro check
+```
+
+The dev server expects the Eva Zig backend running on `localhost:8765`
+(the same port the production binary listens on). Vite proxies both
+`/api/*` and `/ws` so the browser sees a single origin.
+
+> **Note on Vite WS proxy:** Vite's dev WebSocket proxy can drop
+> long-lived `/ws` connections every few minutes. If you see your
+> assistant's response "vanish" after a minute, set
+> `window.__EVA_WS_HOST__ = 'localhost:8765'` in the browser devtools
+> console and reload — `ws.ts` will then connect to the backend
+> directly, bypassing the proxy. (In production
+> `EVA_SERVE_FRONTEND=true` the frontend is served by the backend, so
+> `location.host` already points there and this is a no-op.)
+>
+> The frontend also re-fetches the active chat's messages on every
+> successful WS `open` event after the first, so responses that
+> arrived while the socket was down still appear in the UI.
+
+## Environment
+
+| Eva var                    | Effect                                                    |
+|----------------------------|-----------------------------------------------------------|
+| `EVA_SERVE_FRONTEND=true`  | Make the binary serve `frontend/dist/` from `/`           |
+| `EVA_FRONTEND_DIR=…`       | Override the static dir (default: `frontend/dist`)        |
+| `EVA_API_KEY=…`            | Required for `/api/*` and `/ws`; modal asks for the value |
+| `window.__EVA_WS_HOST__`   | Browser-only override: WS connects to this host in dev     |
+
+The frontend stores the API key in `sessionStorage` (cleared on tab
+close). The WebSocket connection sends it as `?token=…` because the
+zero upgrader doesn't currently inspect upgrade headers.
+
+## Architecture
+
+```
+src/
+  layouts/Base.astro      Shell HTML + <eva-app> custom element
+  pages/index.astro       Loading splash (replaced by boot.ts)
+  lib/
+    boot.ts               mountEva() — the only entry point
+    api.ts                fetch() wrappers for /api/*
+    icons.ts              Inline SVG icon set
+  state/
+    store.ts              Proxy-based reactive store + selectors
+    ws.ts                 WebSocket client with exponential backoff,
+                           re-fetches active chat on reconnect
+  components/
+    Shell.ts              Top-level 2-pane layout, event delegation
+    Sidebar.ts            Chat list, header, status footer
+    MainPanel.ts          Header + MessageList + Input + modals
+    MessageList.ts        Render messages + streaming delta bubble
+    Input.ts              Auto-resizing textarea + send
+    SettingsModal.ts      Read-only model + 4 per-turn overrides
+    TracePanel.ts         Right drawer showing agent steps
+    actions.ts            data-action / data-form / data-change router
+  styles/global.css       @font-face, design tokens, scrollbar,
+                          focus ring, fade-in / pulse animations
+public/
+  fonts/*.woff2           Self-hosted variable woff2 (no CDN)
+  favicon.svg
+```
+
+### Data flow
+
+```
+                boot.ts
+                   │
+                   ▼
+   ┌────────►  store.ts  ──────────► Shell.ts re-renders
+   │              ▲                       │
+   │              │                       ▼
+   │       set() │                  sidebar + main
+   │              │                       │
+   │         ┌────┴────┐                  │
+   │         │  ws.ts  │                  ▼
+   │         │   api   │            actions.ts
+   │         └─────────┘                  │
+   │                                      ▼
+   │                              user interaction
+```
+
+- **Single source of truth**: a module-level `state` object in `store.ts`.
+- **Mutations**: `set(patch)` or `set(s => partial)`. Schedules a rAF
+  flush of subscribers.
+- **Rendering**: `Shell.ts` subscribes once and re-renders both panes
+  on every change. Each component is a pure `renderX(state): string`
+  function — no VDOM, no reconciliation.
+- **Events**: delegated through `data-action`, `data-form`,
+  `data-change` attributes, all routed via `actions.ts`.
+- **Streaming**: WS deltas accumulate in `state.pendingDelta[chatId]`
+  and the `MessageList` renders the tail inline (cursor block + pulse).
+  The full assistant message replaces the tail when `type: "message"`
+  arrives.
+
+### Why no framework?
+
+The whole UI is ~10 components, <2000 LOC of TS + HTML. A VDOM buys
+nothing here and costs bundle size. The trade-off is "re-render the
+whole shell on every state change" which is fine at this scale: full
+innerHTML rewrite is <5 ms in Chrome.
+
+If a future feature needs targeted sub-tree patches (e.g. live tool
+output with thousands of lines), add a `mount(parent, render)` helper
+that diffs the parent's children against a list of keyed nodes. Don't
+adopt a framework.
+
+## Build output
+
+```
+dist/
+  index.html              4 KB  - static HTML with <eva-app> root
+  favicon.svg             1 KB
+  fonts/
+    SpaceGrotesk.woff2   22 KB  - variable font (400..700)
+    DMSans.woff2         36 KB  - variable font (400..500)
+    JetBrainsMono.woff2  31 KB  - static
+  _astro/
+    index.<hash>.css     16 KB  - Tailwind purged
+    hoisted.<hash>.js    28 KB  - all app code (7.8 KB gzipped)
+```
+
+## Conventions
+
+- **No emojis** in source, comments, or UI.
+- **TypeScript strict mode** is on. `astro check` is the source of truth.
+- **No new runtime dependencies** without discussion. The bundle is
+  intentionally tiny.
+- **All async UI work** is awaited; rejections are caught and surfaced
+  as a transient `role: "system"` message in the active chat.
+- **Auth tokens** are session-scoped (sessionStorage), never localStorage.

frontend/astro.config.mjs

@@ -0,0 +1,33 @@
+import { defineConfig } from 'astro/config';
+import tailwind from '@astrojs/tailwind';
+
+// https://astro.build/config
+export default defineConfig({
+  integrations: [tailwind({ applyBaseStyles: true })],
+  output: 'static',
+  server: {
+    port: 4321,
+    host: '0.0.0.0',
+  },
+  vite: {
+    server: {
+      proxy: {
+        // Proxy API + WS to the Zig backend during `astro dev`.
+        // Same shape as the prod single-binary deploy:
+        //   GET    /api/*        -> eva :8765
+        //   WS     /ws           -> eva :8765
+        '/api': {
+          target: 'http://localhost:8765',
+          changeOrigin: true,
+        },
+        '/ws': {
+          target: 'ws://localhost:8765',
+          ws: true,
+          changeOrigin: true,
+        },
+      },
+    },
+  },
+  // Self-host the Space Grotesk + DM Sans woff2 in /public/fonts/.
+  // See docs/frontend/fonts.md for the fetch + @font-face wiring.
+});