Stop CI running two suites at once, and retry rate limits

CI failed on the delegation branch with a 429 from the proxy: token
limit 200000, 17399 remaining. Not a defect — the live delegation
tests are token-hungry, and every push to a PR branch fired two
identical suites concurrently, since the push and pull_request events
both matched.

- Push now only triggers on main. A PR branch is already covered by
  the pull_request event, so this halves both the wall time and the
  tokens spent per branch
- A 429 is retried once before being surfaced. Losing a ten-turn
  delegation to a transient limit wastes far more than waiting out
  the window, and retrying forever would hide a real ceiling. The
  sleep is injectable, so the existing 429 test no longer waits 20
  seconds for real

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

nisse-dev/src/nisse_dev/llm.py

@@ -12,6 +12,7 @@ config change cannot split a task across two planners.
 
 import json
 import os
+import time
 from collections.abc import Mapping
 from dataclasses import asdict, dataclass
 from typing import Any, ClassVar, Protocol
@@ -33,6 +34,14 @@ class LLMError(RuntimeError):
     pass
 
 
+# A rate limit is a transient condition, not a bad request. Losing a
+# ten-turn delegation to one wastes far more tokens than waiting out the
+# window, so retry once before surfacing it (A13's caps still bound the
+# total).
+RATE_LIMIT_STATUS = 429
+RATE_LIMIT_RETRY_S = 20.0
+
+
 class LLMClient(Protocol):
     def complete(
         self,
@@ -82,6 +91,7 @@ class LiteLLMClient:
         *,
         timeout_s: float = 120.0,
         transport: httpx.BaseTransport | None = None,
+        sleep: Any = time.sleep,
     ) -> None:
         self._http = httpx.Client(
             base_url=base_url.rstrip("/"),
@@ -90,6 +100,7 @@ class LiteLLMClient:
             transport=transport,
         )
         self._renderer = OpenAIChatRenderer()
+        self._sleep = sleep
 
     @classmethod
     def from_env(cls, env: Mapping[str, str] = os.environ) -> "LiteLLMClient":
@@ -107,10 +118,9 @@ class LiteLLMClient:
         system: str | None = None,
     ) -> list[CanonicalEvent]:
         body = self._renderer.render(events, tools, model, system=system)
-        try:
-            response = self._http.post("/chat/completions", json=body)
-        except httpx.HTTPError as exc:
-            raise LLMError(f"LLM request failed: {exc}") from exc
+        response = _post_with_rate_limit_retry(
+            self._http, "/chat/completions", body, self._sleep
+        )
         if response.status_code != 200:
             raise LLMError(
                 f"LLM request returned {response.status_code}: {response.text[:500]}"
@@ -176,6 +186,7 @@ class AnthropicPassthroughClient:
         timeout_s: float = 300.0,
         max_tokens: int = 4096,
         transport: httpx.BaseTransport | None = None,
+        sleep: Any = time.sleep,
     ) -> None:
         self._http = httpx.Client(
             base_url=base_url.rstrip("/"),
@@ -189,6 +200,7 @@ class AnthropicPassthroughClient:
         )
         self._renderer = AnthropicMessagesRenderer()
         self._max_tokens = max_tokens
+        self._sleep = sleep
 
     @classmethod
     def from_env(
@@ -210,10 +222,9 @@ class AnthropicPassthroughClient:
         body = self._renderer.render(
             events, tools, model, system=system, max_tokens=self._max_tokens
         )
-        try:
-            response = self._http.post("/v1/messages", json=body)
-        except httpx.HTTPError as exc:
-            raise LLMError(f"passthrough request failed: {exc}") from exc
+        response = _post_with_rate_limit_retry(
+            self._http, "/v1/messages", body, self._sleep
+        )
         if response.status_code != 200:
             raise LLMError(
                 f"passthrough returned {response.status_code}: {response.text[:500]}"
@@ -251,3 +262,17 @@ class AnthropicPassthroughClient:
 
     def close(self) -> None:
         self._http.close()
+
+
+def _post_with_rate_limit_retry(
+    http: httpx.Client, path: str, body: dict[str, Any], sleep: Any
+) -> httpx.Response:
+    for attempt in (1, 2):
+        try:
+            response = http.post(path, json=body)
+        except httpx.HTTPError as exc:
+            raise LLMError(f"LLM request failed: {exc}") from exc
+        if response.status_code != RATE_LIMIT_STATUS or attempt == 2:
+            return response
+        sleep(RATE_LIMIT_RETRY_S)
+    raise AssertionError("unreachable")

nisse-dev/tests/test_llm.py

@@ -11,16 +11,17 @@ from nisse_dev.canonical import (
     UserMessage,
 )
 from nisse_dev.envfile import load_env_file
-from nisse_dev.llm import LiteLLMClient, LLMError, RoleMap
+from nisse_dev.llm import RATE_LIMIT_RETRY_S, LiteLLMClient, LLMError, RoleMap
 
 EVENTS = [StoredEvent(id=1, ts="t", event=UserMessage(text="hi", source="m:1"))]
 
 
-def make_client(handler) -> LiteLLMClient:
+def make_client(handler, sleep=lambda _s: None) -> LiteLLMClient:
     return LiteLLMClient(
         "http://litellm.test/v1",
         "sk-test",
         transport=httpx.MockTransport(handler),
+        sleep=sleep,  # never wait in unit tests
     )
 
 
@@ -109,9 +110,34 @@ def test_non_object_tool_arguments_raise_llm_error() -> None:
 
 
 def test_http_error_status_raises_llm_error() -> None:
-    client = make_client(lambda request: httpx.Response(429, text="rate limited"))
+    client = make_client(lambda request: httpx.Response(500, text="boom"))
+    with pytest.raises(LLMError, match="500"):
+        client.complete(EVENTS, tools=None, model="local/qwen")
+
+
+def test_rate_limit_is_retried_once_then_surfaced() -> None:
+    # A 429 is transient. Losing a long delegation to one costs far more
+    # than waiting out the window, but retrying forever would hide a real
+    # ceiling, so it is retried exactly once.
+    attempts: list[int] = []
+    waited: list[float] = []
+
+    def handler(request: httpx.Request) -> httpx.Response:
+        attempts.append(1)
+        return httpx.Response(429, text="rate limited")
+
+    client = make_client(handler, sleep=waited.append)
     with pytest.raises(LLMError, match="429"):
         client.complete(EVENTS, tools=None, model="local/qwen")
+    assert len(attempts) == 2
+    assert waited == [RATE_LIMIT_RETRY_S]
+
+
+def test_rate_limit_that_clears_succeeds() -> None:
+    responses = [httpx.Response(429, text="slow down"), completion({"content": "hi"})]
+    client = make_client(lambda request: responses.pop(0), sleep=lambda _s: None)
+    [event] = client.complete(EVENTS, tools=None, model="local/qwen")
+    assert isinstance(event, AssistantText)
 
 
 def test_connection_failure_raises_llm_error() -> None: