feat(vision): consult_vision tool + vision settings API

Backend vision update (additive to [email protected] / [email protected],
no version bump).

Contracts mirrored (.dispatch/transport-contract.reference.md):
- VisionSettingsResponse + SetVisionSettingsRequest (GET/PUT /settings/vision).
- Delta note: read_image -> consult_vision; numbered placeholders; compaction.

Tool rendering (ChatView):
- read_image test -> consult_vision (rendering is generic by toolName).
- +2 tests: numbered-placeholder text chunk + [Compacted image] text chunk
  (both regular text chunks, render as-is — no special handling).

New vision feature library (src/features/vision/):
- logic/view-model.ts (32 tests): VisionSettings/VisionSettingsPatch types
  (consumer-defines-port), LoadVisionSettings/SaveVisionSettings ports +
  results, normalizeVisionSettings (network-seam coercion), parseImageLimit/
  imageLimitChanged, compactionModelOptions (vision-capable models via chat's
  public isVisionModel + Auto sentinel), round-trip helpers, imageLimitLabel.
- ui/VisionSettingsView.svelte (9 tests): imageLimit input + Save,
  compactionModel dropdown (Auto + vision-capable models), load-on-mount,
  save-on-change, error/saved feedback.
- index.ts.

Cross-unit seam: isVisionModel added to features/chat public index.ts
(additive); imported through the public surface, not internals.

Store wiring (src/app/store.svelte.ts):
- visionSettings state + refreshVisionSettings (GET /settings/vision,
  normalized at the seam) + setVisionSettings (PUT, partial, returns merged) +
  VisionSettingsResult; seeded on boot; exposed on AppStore. +4 store tests.

Mounted in App.svelte: new "Vision" sidebar view kind + VisionSettingsView
in viewContent (not conversation-scoped); load/save adapters; visionManifest.

Verification: svelte-check 0/0; vitest 948/948 (run twice, +47 since the
prior vision commit); biome clean; vite build OK. See backend-handoff.md §2j.

Not merged or pushed.

2 files changed, 50 insertions, 8 deletions

diff --git a/src/features/chat/index.ts b/src/features/chat/index.ts
index ddb094d..8694691 100644
--- a/src/features/chat/index.ts
+++ b/src/features/chat/index.ts
@@ -6,6 +6,7 @@ export type {
 } from "../../core/chunks";
 export { groupRenderedChunks, viewProviderRetry } from "../../core/chunks";
 export type { TurnMetricsEntry } from "../../core/metrics";
+export { isVisionModel } from "./model-select";
 export type { ChatTransport, HistorySync, HistoryWindow, MetricsSync } from "./ports";
 export type {
   EffortOption,
diff --git a/src/features/chat/ui.test.ts b/src/features/chat/ui.test.ts
index af32f72..b0aa6f0 100644
--- a/src/features/chat/ui.test.ts
+++ b/src/features/chat/ui.test.ts
@@ -655,8 +655,10 @@ describe("ChatView", () => {
     expect(container.querySelector("img")?.getAttribute("src")).toBe(url);
   });
 
-  it("renders a read_image tool call/result like any other tool", () => {
-    // The read_image tool is available to all models; it is a normal tool call.
+  it("renders a consult_vision tool call/result like any other tool", () => {
+    // read_image is GONE — replaced by consult_vision (opens a vision-model
+    // conversation, attaches the image + question, returns the answer). It is
+    // a normal tool call: rendered generically by toolName.
     const chunks: RenderedChunk[] = [
       {
         seq: 1,
@@ -664,8 +666,8 @@ describe("ChatView", () => {
         chunk: {
           type: "tool-call",
           toolCallId: "tc1",
-          toolName: "read_image",
-          input: { path: "/tmp/screenshot.png" },
+          toolName: "consult_vision",
+          input: { question: "what is in this image?", imageIds: [1] },
         },
         provisional: false,
       },
@@ -675,8 +677,8 @@ describe("ChatView", () => {
         chunk: {
           type: "tool-result",
           toolCallId: "tc1",
-          toolName: "read_image",
-          content: "a screenshot of the desktop",
+          toolName: "consult_vision",
+          content: "a red square on a white background",
           isError: false,
         },
         provisional: false,
@@ -685,8 +687,47 @@ describe("ChatView", () => {
 
     render(ChatView, { props: { chunks } });
 
-    expect(screen.getAllByText("read_image").length).toBeGreaterThan(0);
-    expect(screen.getByText("a screenshot of the desktop")).toBeInTheDocument();
+    expect(screen.getAllByText("consult_vision").length).toBeGreaterThan(0);
+    expect(screen.getByText("a red square on a white background")).toBeInTheDocument();
+  });
+
+  it("renders a non-vision placeholder text chunk as-is", () => {
+    // A non-vision model gets a numbered placeholder (a regular text chunk)
+    // instead of an auto-transcription. Renders like any text chunk.
+    const chunks: RenderedChunk[] = [
+      {
+        seq: 1,
+        role: "user",
+        chunk: {
+          type: "text",
+          text: "[Image 1 attached — call consult_vision with imageIds=[1] and a specific question to analyze it]",
+        },
+        provisional: false,
+      },
+    ];
+
+    render(ChatView, { props: { chunks } });
+
+    expect(screen.getByText(/\[Image 1 attached/)).toBeInTheDocument();
+    expect(screen.getByText(/consult_vision with imageIds/)).toBeInTheDocument();
+  });
+
+  it("renders a compacted-image text chunk as-is", () => {
+    // Image compaction transcribes old images to [Compacted image]: <desc>.
+    // Regular text chunk — render as-is.
+    const chunks: RenderedChunk[] = [
+      {
+        seq: 1,
+        role: "user",
+        chunk: { type: "text", text: "[Compacted image]: a chart showing rising sales" },
+        provisional: false,
+      },
+    ];
+
+    render(ChatView, { props: { chunks } });
+
+    expect(screen.getByText(/\[Compacted image\]/)).toBeInTheDocument();
+    expect(screen.getByText(/rising sales/)).toBeInTheDocument();
   });
 });