fix(cron): respect subagents.model in isolated cron sessions (#11474)

* fix(cron): respect subagents.model in isolated cron sessions

* fix(cron): enforce model allowlist for subagents.model

* Cron: fix isolated subagent model gate regressions

---------

Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/agents/model-selection.test.ts

@@ -6,8 +6,9 @@ import {
   inferUniqueProviderFromConfiguredModels,
   parseModelRef,
   buildModelAliasIndex,
-  modelKey,
+  normalizeModelSelection,
   normalizeProviderId,
+  modelKey,
   resolveAllowedModelRef,
   resolveConfiguredModelRef,
   resolveModelRefFromString,
@@ -470,3 +471,31 @@ describe("model-selection", () => {
     });
   });
 });
+
+describe("normalizeModelSelection", () => {
+  it("returns trimmed string for string input", () => {
+    expect(normalizeModelSelection("ollama/llama3.2:3b")).toBe("ollama/llama3.2:3b");
+  });
+
+  it("returns undefined for empty/whitespace string", () => {
+    expect(normalizeModelSelection("")).toBeUndefined();
+    expect(normalizeModelSelection("   ")).toBeUndefined();
+  });
+
+  it("extracts primary from object", () => {
+    expect(normalizeModelSelection({ primary: "google/gemini-2.5-flash" })).toBe(
+      "google/gemini-2.5-flash",
+    );
+  });
+
+  it("returns undefined for object without primary", () => {
+    expect(normalizeModelSelection({ fallbacks: ["a"] })).toBeUndefined();
+    expect(normalizeModelSelection({})).toBeUndefined();
+  });
+
+  it("returns undefined for null/undefined/number", () => {
+    expect(normalizeModelSelection(undefined)).toBeUndefined();
+    expect(normalizeModelSelection(null)).toBeUndefined();
+    expect(normalizeModelSelection(42)).toBeUndefined();
+  });
+});

src/agents/model-selection.ts

@@ -208,22 +208,6 @@ export function inferUniqueProviderFromConfiguredModels(params: {
   return providers.values().next().value;
 }
 
-export function normalizeModelSelection(value: unknown): string | undefined {
-  if (typeof value === "string") {
-    const trimmed = value.trim();
-    return trimmed || undefined;
-  }
-  if (!value || typeof value !== "object") {
-    return undefined;
-  }
-  const primary = (value as { primary?: unknown }).primary;
-  if (typeof primary === "string") {
-    const trimmed = primary.trim();
-    return trimmed || undefined;
-  }
-  return undefined;
-}
-
 export function resolveAllowlistModelKey(raw: string, defaultProvider: string): string | null {
   const parsed = parseModelRef(raw, defaultProvider);
   if (!parsed) {
@@ -612,3 +596,23 @@ export function resolveHooksGmailModel(params: {
 
   return resolved?.ref ?? null;
 }
+
+/**
+ * Normalize a model selection value (string or `{primary?: string}`) to a
+ * plain trimmed string.  Returns `undefined` when the input is empty/missing.
+ * Shared by sessions-spawn and cron isolated-agent model resolution.
+ */
+export function normalizeModelSelection(value: unknown): string | undefined {
+  if (typeof value === "string") {
+    const trimmed = value.trim();
+    return trimmed || undefined;
+  }
+  if (!value || typeof value !== "object") {
+    return undefined;
+  }
+  const primary = (value as { primary?: unknown }).primary;
+  if (typeof primary === "string" && primary.trim()) {
+    return primary.trim();
+  }
+  return undefined;
+}