test(fallback): restore returns to a Codex primary whose quota reopened early

tests/agent/test_fallback_restore_codex_early_reopen.py

@@ -0,0 +1,85 @@
+"""A session pinned to its fallback returns to a Codex primary whose quota window reopened early.
+
+A Codex 429 benches the pool entry and arms the session's ``_rate_limited_until`` until a
+``resets_at`` that can be days out. The pool's throttled usage probe notices an early reopen, but
+only on ``select()``; the fallback restore gates on the two cooldowns and never reached it.
+"""
+
+import json
+import time
+from unittest.mock import MagicMock, patch
+
+from run_agent import AIAgent
+
+CODEX_URL = "https://chatgpt.com/backend-api/codex"
+FALLBACK = {"provider": "openrouter", "model": "anthropic/claude-sonnet-4"}
+
+
+def _write_exhausted_codex_pool(home, reset_in_seconds):
+    reset_at = time.time() + reset_in_seconds
+    entry = {
+        "id": "codex-1",
+        "label": "codex-login",
+        "auth_type": "oauth",
+        "priority": 0,
+        "source": "device_code",
+        "access_token": "token",
+        "refresh_token": "refresh",
+        "base_url": CODEX_URL,
+        "last_status": "exhausted",
+        "last_status_at": time.time(),
+        "last_error_code": 429,
+        "last_error_reason": "usage_limit_reached",
+        "last_error_message": "The usage limit has been reached",
+        "last_error_reset_at": reset_at,
+    }
+    (home / "auth.json").write_text(json.dumps({"version": 1, "credential_pool": {"openai-codex": [entry]}}))
+
+
+def _fallback_agent():
+    tool_defs = [{"type": "function", "function": {
+        "name": "web_search", "description": "x", "parameters": {"type": "object", "properties": {}}}}]
+    with (
+        patch("model_tools.get_tool_definitions", return_value=tool_defs),
+        patch("model_tools.check_toolset_requirements", return_value={}),
+        patch("agent.process_bootstrap.OpenAI"),
+    ):
+        agent = AIAgent(
+            api_key="test-key-12345678", base_url="https://my-llm.example.com/v1", provider="custom",
+            quiet_mode=True, skip_context_files=True, skip_memory=True, fallback_model=FALLBACK,
+        )
+    agent.client = MagicMock()
+    agent._primary_runtime = {**agent._primary_runtime, "provider": "openai-codex", "base_url": CODEX_URL}
+    client = MagicMock(api_key="fallback-key-1234", base_url="https://openrouter.ai/api/v1")
+    with patch("agent.auxiliary_client.resolve_provider_client", return_value=(client, None)):
+        assert agent._try_activate_fallback() is True
+    # The weekly reset the provider declared, armed by _arm_rate_limit_cooldown.
+    agent._rate_limited_until = time.monotonic() + 3 * 86400
+    agent._swap_credential = MagicMock()
+    return agent
+
+
+def _restore(agent, quota_restored):
+    with (
+        patch("hermes_cli.auth._probe_codex_quota_restored", return_value=quota_restored),
+        patch("agent.process_bootstrap.OpenAI", return_value=MagicMock()),
+    ):
+        return agent._restore_primary_runtime()
+
+
+def test_returns_to_primary_when_quota_reopens_before_declared_reset(tmp_path, monkeypatch):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    _write_exhausted_codex_pool(tmp_path, reset_in_seconds=3 * 86400)
+    agent = _fallback_agent()
+
+    assert _restore(agent, quota_restored=True) is True
+    assert agent._fallback_activated is False
+
+
+def test_stays_on_fallback_while_quota_is_still_spent(tmp_path, monkeypatch):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    _write_exhausted_codex_pool(tmp_path, reset_in_seconds=3 * 86400)
+    agent = _fallback_agent()
+
+    assert _restore(agent, quota_restored=False) is False
+    assert agent._fallback_activated is True