Interface●Since v1.1

ContentBlockDeltaEvent

interface ContentBlockDeltaEvent

Properties

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Emitted for each incremental update within a content block.

The delta field carries the incremental content block update. Accumulation rules:

text-delta → append text to the active block's text field
reasoning-delta → append reasoning to the active block's reasoning field
data-delta → append data to the active block's data field
block-delta → shallow-merge fields onto the active block

// Text token
{ event: "content-block-delta", index: 0,
  delta: { type: "text-delta", text: " world" } }

// Tool call args snapshot
{ event: "content-block-delta", index: 1,
  delta: { type: "block-delta",
    fields: { type: "tool_call_chunk", args: '{"q":"wea' } } } }

// Provider-specific field (e.g., signature)
{ event: "content-block-delta", index: 0,
  delta: { type: "block-delta",
    fields: { type: "reasoning", signature: "sig_abc" } } }

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ContentBlockDeltaEvent

Properties

Example