Unify dynamic fallback chains for background subagents

src/shared/fallback-chain-from-models.test.ts

@@ -0,0 +1,48 @@
+import { describe, test, expect } from "bun:test"
+import { buildFallbackChainFromModels, parseFallbackModelEntry } from "./fallback-chain-from-models"
+
+describe("fallback-chain-from-models", () => {
+  test("parses provider/model entry with parenthesized variant", () => {
+    //#given
+    const fallbackModel = "openai/gpt-5.2(high)"
+
+    //#when
+    const parsed = parseFallbackModelEntry(fallbackModel, "quotio")
+
+    //#then
+    expect(parsed).toEqual({
+      providers: ["openai"],
+      model: "gpt-5.2",
+      variant: "high",
+    })
+  })
+
+  test("uses default provider when fallback model omits provider prefix", () => {
+    //#given
+    const fallbackModel = "glm-5"
+
+    //#when
+    const parsed = parseFallbackModelEntry(fallbackModel, "quotio")
+
+    //#then
+    expect(parsed).toEqual({
+      providers: ["quotio"],
+      model: "glm-5",
+      variant: undefined,
+    })
+  })
+
+  test("builds fallback chain from normalized fallback_models input", () => {
+    //#given
+    const fallbackModels = ["quotio/kimi-k2.5", "gpt-5.2 medium"]
+
+    //#when
+    const chain = buildFallbackChainFromModels(fallbackModels, "quotio")
+
+    //#then
+    expect(chain).toEqual([
+      { providers: ["quotio"], model: "kimi-k2.5", variant: undefined },
+      { providers: ["quotio"], model: "gpt-5.2", variant: "medium" },
+    ])
+  })
+})