fix: shrink images to reported provider dimension limit (#45979)

Parse provider-reported image pixel ceilings so many-image Anthropic requests can recover by shrinking Retina screenshots below the stricter limit instead of retrying the same rejected payload.

agent/conversation_loop.py

@@ -71,6 +71,35 @@ logger = logging.getLogger(__name__)
 INTERRUPT_WAITING_FOR_MODEL_PREFIX = "Operation interrupted: waiting for model response ("
 
 
+def _image_error_max_dimension(error: Exception) -> Optional[int]:
+    """Extract a provider-reported image dimension ceiling, if present."""
+    parts = []
+    for value in (
+        error,
+        getattr(error, "message", None),
+        getattr(error, "body", None),
+    ):
+        if value:
+            try:
+                parts.append(str(value))
+            except Exception:
+                pass
+    text = " ".join(parts).lower()
+    if "image" not in text or "dimension" not in text or "max allowed size" not in text:
+        return None
+
+    match = re.search(r"max allowed size(?:\s+for [^:]+)?:\s*(\d{3,5})\s*pixels?", text)
+    if not match:
+        return None
+    try:
+        max_dimension = int(match.group(1))
+    except ValueError:
+        return None
+    if 512 <= max_dimension <= 8000:
+        return max_dimension
+    return None
+
+
 def _ollama_context_limit_error(agent: Any, request_tokens: int) -> Optional[str]:
     """Return a user-facing error when Ollama is loaded with too little context."""
     if not getattr(agent, "tools", None):
@@ -2070,7 +2099,11 @@ def run_conversation(
                     and not _retry.image_shrink_retry_attempted
                 ):
                     _retry.image_shrink_retry_attempted = True
-                    if agent._try_shrink_image_parts_in_messages(api_messages):
+                    image_max_dimension = _image_error_max_dimension(api_error) or 8000
+                    if agent._try_shrink_image_parts_in_messages(
+                        api_messages,
+                        max_dimension=image_max_dimension,
+                    ):
                         agent._vprint(
                             f"{agent.log_prefix}📐 Image(s) exceeded provider size limit — "
                             f"shrank and retrying...",