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Streaming Events

Streaming & events

Section titled “Streaming & events”

Event types emitted by query()

Section titled “Event types emitted by query()”
  • SDKUserMessage — User input (usually only in replay mode).
  • SDKAssistantMessage — Claude’s response with tool calls.
  • SDKPartialAssistantMessage — Streaming chunk (when includePartialMessages: true).
  • SDKResultMessage — Final result with usage and cost.
  • SDKSystemMessage — Session metadata (init, status changes).
  • SDKStatusMessage — Progress updates (e.g., status: 'compacting').
  • SDKRateLimitEvent — Rate limit status changes.
  • SDKStreamlinedTextMessage — Compacted text summary (internal).

Configuration flags

Section titled “Configuration flags”
  • includePartialMessages: Emit partial chunks during streaming (default: false).
  • includeThinking: Include thinking blocks in assistant messages (default: false, model-dependent).
  • includeHookEvents: Emit hook invocation events (default: false; internal feature).
  • includeReplayMessages: Emit replay messages when resuming session (default: false).

Backpressure / flow control

Section titled “Backpressure / flow control”

The async generator pauses if the consumer doesn’t read fast enough, providing implicit backpressure. No explicit flow-control API; iteration speed controls throughput.

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