feat(vision): image paste + transcript image rendering + vision badge

Vision & vision-handoff frontend (consumes the backend's additive
[email protected] / [email protected] image types — no version bump).

Contracts mirrored:
- .dispatch/wire.reference.md: ImageChunk added to the Chunk union +
  ImageChunk/ImageInput interfaces.
- .dispatch/transport-contract.reference.md: ChatRequest.images,
  ModelMetadata.vision, + ImageChunk/ImageInput re-exports.

Core (core/chunks):
- conformance: assertChunkExhaustive handles the new 'image' variant
  (the guard caught it — its purpose).
- appendUserMessage(state, text, images?) echoes a [text, image, ...]
  user run; the user-message event dedup scans the trailing user run
  (not just the last chunk) so an image-bearing echo doesn't duplicate
  the text; applyHistory's during-gen dedup matches a multi-chunk echo
  by content equality (chunkContentEquals + trailingRun helpers).

UI:
- ChatView renders user 'image' chunks as lazy <img> bubbles; a
  non-vision model's persisted [image, analysis-text] both render.
  read_image tool renders generically (no special-casing).
- Composer: clipboard paste / file picker / drag-drop of images ->
  base64 data URLs, thumbnail previews with remove, forwarded on
  chat.send (omitted when none). Image-only sends allowed; steering
  (chat.queue) never forwards images.
- ModelSelector: vision badge (isVisionModel) marks vision-capable
  models; indicator shows native-vision vs vision-handoff hint.

Store wiring: ChatStore.send + AppStore.send + App.svelte handleSend
thread images through; chat.send still omits cwd (only images added).

Verification: svelte-check 0/0; vitest 901/901 (run twice, +34 new);
biome clean; vite build OK. See backend-handoff.md §2j.

Not merged or pushed.

1 files changed, 11 insertions, 1 deletions

diff --git a/src/features/chat/ui/ChatView.svelte b/src/features/chat/ui/ChatView.svelte
index e72f639..8081951 100644
--- a/src/features/chat/ui/ChatView.svelte
+++ b/src/features/chat/ui/ChatView.svelte
@@ -95,11 +95,21 @@
 
 {#snippet chunkRow(rendered: RenderedChunk)}
   {#if rendered.role === "user"}
-    <!-- User: a speech bubble, left-aligned -->
+    <!-- User: a speech bubble, left-aligned. A user message may be multi-chunk
+         ([text, image, image, …]); each chunk renders in its own bubble (the
+         image's url is a base64 data URL or an https URL — render it directly). -->
     <div class="chat chat-start">
       <div class="chat-bubble chat-bubble-primary">
         {#if rendered.chunk.type === "text"}
           <p>{rendered.chunk.text}</p>
+        {:else if rendered.chunk.type === "image"}
+          <img
+            src={rendered.chunk.url}
+            alt={rendered.chunk.mimeType ?? "pasted image"}
+            loading="lazy"
+            decoding="async"
+            class="max-h-80 max-w-full rounded"
+          />
         {/if}
       </div>
     </div>