fix(execution): only strip images on image-rejection errors (#1461)

* fix(execution): only strip images on image-rejection errors

The image-strip recovery fired on any 400/404/422, wiping a session's screenshots and replaying the turn on unrelated errors (e.g. an upstream incomplete-tool-call 400, a context overflow). Require an image-related message too.

* fix(execution): match only replies that mean the model takes no images

* fix(execution): match DeepSeek's image rejection

* fix(execution): guess at Vercel AI Gateway's image rejection

strix/core/execution.py

@@ -6,6 +6,7 @@ import asyncio
 import contextlib
 import inspect
 import logging
+import re
 import uuid
 from collections.abc import Callable
 from dataclasses import replace
@@ -57,6 +58,18 @@ logger = logging.getLogger(__name__)
 StreamEventSink = Callable[[str, Any], None]
 
 _INPUT_REJECTION_CODES = frozenset({400, 404, 422})
+# Replies meaning "this model takes no images", not image errors in general: a
+# context overflow that counts "image/vision expansion" must not match.
+_IMAGE_REJECTION = re.compile(
+    r"no endpoints found that support image input"  # OpenRouter
+    r"|image_url is only supported by certain models"  # OpenAI
+    r"|is not a multimodal model|at most 0 image\(s\)"  # vLLM
+    r"|does not support image input"  # LiteLLM's Fireworks check
+    r"|doesn't support the image field"  # Bedrock Converse
+    r"|unknown variant `image_url`"  # DeepSeek, e.g. via Vercel AI Gateway
+    r"|'[^']*image[^']*' functionality not supported",  # Vercel AI Gateway (AI SDK), unverified
+    re.IGNORECASE,
+)
 _MAX_COMPACTIONS_PER_CYCLE = 2
 
 
@@ -156,6 +169,12 @@ def _model_error_status_code(exc: BaseException) -> int | None:
     return code if isinstance(code, int) else None
 
 
+def _is_image_rejection(exc: BaseException) -> bool:
+    return _model_error_status_code(exc) in _INPUT_REJECTION_CODES and bool(
+        _IMAGE_REJECTION.search(str(exc))
+    )
+
+
 def _is_transient_model_error(exc: BaseException) -> bool:
     if codex.is_content_guardrail_error(exc):
         return False
@@ -831,11 +850,7 @@ async def _run_cycle(  # noqa: PLR0912, PLR0915
             await coordinator.trigger_budget_stop()
             raise
         except Exception as exc:
-            if (
-                image_strips < 3
-                and session is not None
-                and getattr(exc, "status_code", None) in _INPUT_REJECTION_CODES
-            ):
+            if image_strips < 3 and session is not None and _is_image_rejection(exc):
                 try:
                     stripped = await strip_all_images_from_session(session)
                 except Exception:

tests/test_execution_transient_retry.py

@@ -109,6 +109,7 @@ def _patch_fast_backoff(monkeypatch: pytest.MonkeyPatch) -> None:
 async def _run_once(
     monkeypatch: pytest.MonkeyPatch,
     streams: list[_FakeStream],
+    session: Any = None,
 ) -> Any:
     _patch_fast_backoff(monkeypatch)
     calls = {"n": 0}
@@ -131,7 +132,7 @@ async def _run_once(
         run_config=cast("RunConfig", object()),
         context={},
         max_turns=5,
-        session=None,
+        session=session,
         interactive=False,
         event_sink=None,
         hooks=None,
@@ -172,3 +173,75 @@ async def test_run_cycle_does_not_retry_permanent_error(
     streams = [_FakeStream(exc=bad_request), _FakeStream()]
     with pytest.raises(BadRequestError):
         await _run_once(monkeypatch, streams)
+
+
+@pytest.mark.parametrize(
+    ("status", "message", "expected"),
+    [
+        (
+            404,
+            "litellm.NotFoundError: NotFoundError: OpenrouterException - "
+            '{"error":{"message":"No endpoints found that support image input","code":404,'
+            '"metadata":{"failed_routing_step":"Filter by Image Support"}}}',
+            True,
+        ),
+        (400, "Invalid content type. image_url is only supported by certain models.", True),
+        (400, "my-model is not a multimodal model", True),
+        (400, "This model doesn't support the image field for user messages.", True),
+        (422, "messages[3]: unknown variant `image_url`, expected `text`", True),
+        (400, "'Image URLs in user messages' functionality not supported.", True),
+        (
+            400,
+            "OpenRouterException: Message: This model's maximum context length is 1048576 "
+            "tokens, but the request requires 1073484 tokens (942412 input including "
+            "image/vision expansion + 131072 for the completion). Reduce the input length "
+            "or max_tokens.",
+            False,
+        ),
+        (400, "At most 5 image(s) may be provided in one prompt.", False),
+        (
+            400,
+            "Upstream error from Relace: Generation stopped with an incomplete tool call",
+            False,
+        ),
+        (500, "No endpoints found that support image input", False),
+    ],
+)
+def test_is_image_rejection(status: int, message: str, expected: bool) -> None:
+    exc = APIStatusError(message, response=httpx.Response(status, request=_request()), body=None)
+    assert execution._is_image_rejection(exc) is expected
+
+
+async def _run_with_image_session(
+    monkeypatch: pytest.MonkeyPatch, streams: list[_FakeStream]
+) -> tuple[Any, int, int]:
+    strips = {"n": 0}
+
+    async def _fake_strip(_session: Any) -> bool:
+        strips["n"] += 1
+        return True
+
+    async def _no_compact(*_args: Any, **_kwargs: Any) -> bool:
+        return False
+
+    monkeypatch.setattr(execution, "strip_all_images_from_session", _fake_strip)
+    monkeypatch.setattr(execution, "_compact_session", _no_compact)
+    result, attempts, _coordinator = await _run_once(monkeypatch, streams, session=object())
+    return result, attempts, strips["n"]
+
+
+@pytest.mark.asyncio
+async def test_run_cycle_strips_images_on_image_rejection(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    rejection = APIStatusError(
+        "No endpoints found that support image input",
+        response=httpx.Response(status_code=404, request=_request()),
+        body=None,
+    )
+    streams = [_FakeStream(exc=rejection), _FakeStream()]
+    result, attempts, strips = await _run_with_image_session(monkeypatch, streams)
+
+    assert result is streams[1]
+    assert attempts == 2
+    assert strips == 1