fix(cli): dedupe generated installer fallback models

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

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

src/cli/config-manager/generate-omo-config.test.ts

@@ -127,10 +127,19 @@ describe("generateOmoConfig - model fallback system", () => {
 
     //#then
     expect(agents.sisyphus.model).toBe("anthropic/claude-opus-4-6")
-    expect(agents.sisyphus.fallback_models?.map((entry) => entry.model)).toContain("openai/gpt-5.4")
+    expect(agents.sisyphus.fallback_models).toEqual([
-    expect(agents.sisyphus.fallback_models?.find((entry) => entry.model === "openai/gpt-5.4")?.variant).toBe("medium")
+      {
+        model: "openai/gpt-5.4",
+        variant: "medium",
+      },
+    ])
     expect(categories.deep.model).toBe("openai/gpt-5.4")
-    expect(categories.deep.fallback_models?.map((entry) => entry.model)).toContain("anthropic/claude-opus-4-6")
+    expect(categories.deep.fallback_models).toEqual([
+      {
+        model: "anthropic/claude-opus-4-6",
+        variant: "max",
+      },
+    ])
   })
 
   test("uses haiku for explore when Claude max20", () => {

src/cli/model-fallback.ts

@@ -47,12 +47,18 @@ function attachFallbackModels<T extends AgentConfig | CategoryConfig>(
       .filter((provider) => isProviderAvailable(provider, availability))
       .map((provider) => toFallbackModelObject(entry, provider))
   )
-  const primaryIndex = expandedFallbacks.findIndex((entry) => entry.model === config.model)
+  const uniqueFallbacks = expandedFallbacks.filter((entry, index, allEntries) =>
+    allEntries.findIndex((candidate) =>
+      candidate.model === entry.model &&
+      candidate.variant === entry.variant
+    ) === index
+  )
+  const primaryIndex = uniqueFallbacks.findIndex((entry) => entry.model === config.model)
   if (primaryIndex === -1) {
     return config
   }
 
-  const fallbackModels = expandedFallbacks.slice(primaryIndex + 1)
+  const fallbackModels = uniqueFallbacks.slice(primaryIndex + 1)
   if (fallbackModels.length === 0) {
     return config
   }