refactor mode selection into delegate tool that spawns subagents (#265)

test/agnostic/delegateMulti.ts

@@ -0,0 +1,56 @@
+import type { AgentResult, TestRunnerOptions, ValidationCheck } from "../utils.ts";
+import { defineFixture, getAgentOutput, getStructuredOutput } from "../utils.ts";
+
+/**
+ * delegateMulti test - validates multi-phase delegation with context passing.
+ *
+ * the orchestrator delegates twice:
+ * 1. first to Plan mode (subagent calls set_output with PHASE_1_MARKER)
+ * 2. then to Plan mode again with context from phase 1 (subagent calls set_output with MULTI_DELEGATE_PASSED)
+ *
+ * validates that both delegations executed and the final set_output value is correct.
+ */
+
+const fixture = defineFixture(
+  {
+    prompt: `This is a multi-delegation test. You must delegate exactly twice:
+
+Phase 1: Delegate to Plan mode with mini effort. Pass these instructions:
+"Your task is to call set_output with the value 'PHASE_1_MARKER'. Do not create plans or PRs."
+
+Phase 2: After Phase 1 completes, delegate to Plan mode again with mini effort. Pass these instructions (include the result from Phase 1 as context):
+"Your task is to call set_output with the value 'MULTI_DELEGATE_PASSED'. Do not create plans or PRs."
+
+Both delegations must complete successfully.`,
+    effort: "mini",
+    timeout: "8m",
+  },
+  { localOnly: true }
+);
+
+function validator(result: AgentResult): ValidationCheck[] {
+  const output = getStructuredOutput(result);
+  const agentOutput = getAgentOutput(result);
+
+  const setOutputCalled = output !== null;
+  // the last set_output call wins — should be from Phase 2
+  const finalValue = setOutputCalled && /MULTI_DELEGATE_PASSED/i.test(output);
+
+  // count delegation evidence — match the exact log line format from the delegate handler
+  const delegationMatches = agentOutput.match(/» delegating to/g);
+  const twoDelegations = delegationMatches !== null && delegationMatches.length >= 2;
+
+  return [
+    { name: "set_output", passed: setOutputCalled },
+    { name: "final_value", passed: finalValue },
+    { name: "two_delegations", passed: twoDelegations },
+  ];
+}
+
+export const test: TestRunnerOptions = {
+  name: "delegate-multi",
+  fixture,
+  validator,
+  env: { GITHUB_REPOSITORY: "pullfrog/test-repo" },
+  tags: ["agnostic"],
+};