fix: rename test file to .ts extension

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/tools/look-at/multimodal-fallback-chain.test.ts

@@ -0,0 +1,31 @@
+describe("buildMultimodalLookerFallbackChain", () => {
+  it("builds fallback chain from vision-capable models", async () => {
+    // given
+    const { buildMultimodalLookerFallbackChain } = await import("./multimodal-fallback-chain")
+    const visionCapableModels = [
+      { providerID: "openai", modelID: "gpt-5.4" },
+      { providerID: "opencode", modelID: "gpt-5.4" },
+    ]
+
+    // when
+    const result = buildMultimodalLookerFallbackChain(visionCapableModels)
+
+    // then
+    const gpt54Entries = result.filter((entry) => entry.model === "gpt-5.4")
+    expect(gpt54Entries.length).toBeGreaterThan(0)
+  })
+
+  it("avoids duplicates when adding hardcoded entries", async () => {
+    // given
+    const { buildMultimodalLookerFallbackChain } = await import("./multimodal-fallback-chain")
+    const visionCapableModels = [{ providerID: "openai", modelID: "gpt-5.4" }]
+
+    // when
+    const result = buildMultimodalLookerFallbackChain(visionCapableModels)
+
+    // then
+    expect(result.length).toBeGreaterThan(0)
+    expect(result[0].model).toBe("gpt-5.4")
+    expect(result[0].providers).toContain("openai")
+  })
+})