fix(models): normalize trailing @profile parsing across resolver paths

Co-authored-by: Vincent Koc <vincentkoc@ieee.org>
Co-authored-by: Marcus Castro <mcaxtr@gmail.com>
Co-authored-by: Brandon Wise <brandonawise@gmail.com>

src/agents/model-ref-profile.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, it } from "vitest";
+import { splitTrailingAuthProfile } from "./model-ref-profile.js";
+
+describe("splitTrailingAuthProfile", () => {
+  it("returns trimmed model when no profile suffix exists", () => {
+    expect(splitTrailingAuthProfile(" openai/gpt-5 ")).toEqual({
+      model: "openai/gpt-5",
+    });
+  });
+
+  it("splits trailing @profile suffix", () => {
+    expect(splitTrailingAuthProfile("openai/gpt-5@work")).toEqual({
+      model: "openai/gpt-5",
+      profile: "work",
+    });
+  });
+
+  it("keeps @-prefixed path segments in model ids", () => {
+    expect(splitTrailingAuthProfile("openai/@cf/openai/gpt-oss-20b")).toEqual({
+      model: "openai/@cf/openai/gpt-oss-20b",
+    });
+  });
+
+  it("supports trailing profile override after @-prefixed path segments", () => {
+    expect(splitTrailingAuthProfile("openai/@cf/openai/gpt-oss-20b@cf:default")).toEqual({
+      model: "openai/@cf/openai/gpt-oss-20b",
+      profile: "cf:default",
+    });
+  });
+
+  it("keeps openrouter preset paths without profile override", () => {
+    expect(splitTrailingAuthProfile("openrouter/@preset/kimi-2-5")).toEqual({
+      model: "openrouter/@preset/kimi-2-5",
+    });
+  });
+
+  it("supports openrouter preset profile overrides", () => {
+    expect(splitTrailingAuthProfile("openrouter/@preset/kimi-2-5@work")).toEqual({
+      model: "openrouter/@preset/kimi-2-5",
+      profile: "work",
+    });
+  });
+
+  it("does not split when suffix after @ contains slash", () => {
+    expect(splitTrailingAuthProfile("provider/foo@bar/baz")).toEqual({
+      model: "provider/foo@bar/baz",
+    });
+  });
+});