Render the assistant's replies as Markdown (#118)

Render assistant chat output as GFM Markdown (tables, lists, code, headings), lazy-loaded so the ~150 KB renderer only ships when an assistant message shows. Hardened per review: no <img> (exfiltration-beacon guard), no raw HTML, error-boundary + stale-chunk recovery around the lazy chunk, GFM column alignment, and memoized parsing.

Co-authored-by: Steve Dudenhoeffer <[email protected]>

web/src/lib/lazyPage.ts

@@ -0,0 +1,41 @@
+import { lazy, type ComponentType } from 'react'
+
+/**
+ * Lazily load a component by its named export, with recovery for the stale-chunk
+ * problem. A push to main redeploys, so a still-open app references chunk hashes
+ * the server has just replaced; that import 404s and React.lazy MEMOIZES the
+ * rejection, so a "Try again" can never recover — the user is stuck until a manual
+ * hard reload. On the first such failure we reload once (fetching the fresh index
+ * + hashes); a session flag stops a reload loop, and a success clears it so a
+ * later genuine failure can reload again.
+ *
+ * Shared by the route splits (router.tsx) and any feature-level lazy load (the
+ * assistant's Markdown renderer), so they all get the same recovery.
+ */
+export function lazyPage<M, K extends keyof M>(load: () => Promise<M>, name: K) {
+  // Preserve the component's own prop type so callers keep type-checked props
+  // (e.g. MarkdownMessage's `children: string`), rather than erasing to `{}`.
+  type C = M[K] extends ComponentType<infer P> ? ComponentType<P> : never
+  return lazy<C>(async () => {
+    try {
+      const mod = await load()
+      try {
+        sessionStorage.removeItem('pansy:chunk-reload')
+      } catch {
+        /* storage unavailable — fine */
+      }
+      return { default: mod[name] as C }
+    } catch (err) {
+      try {
+        if (!sessionStorage.getItem('pansy:chunk-reload')) {
+          sessionStorage.setItem('pansy:chunk-reload', '1')
+          window.location.reload()
+          return await new Promise<{ default: C }>(() => {}) // hold for the reload
+        }
+      } catch {
+        /* storage unavailable — fall through to surface the error */
+      }
+      throw err // already reloaded once (or can't); let the error boundary show it
+    }
+  })
+}