Struct CompletionBuilder 

pub struct CompletionBuilder { /* private fields */ }

Reassembles a stream of TextDeltas back into a Completion — the inverse of completion_deltas, for a caller that consumed a stream incrementally (relaying it to a client, say) and still wants the whole answer at the end: to log, to persist, to hand to the tool loop.

Semantics

• TextDelta::Text pieces concatenate in order.
• TextDelta::Reasoning is dropped: reasoning is not part of a completion.
• TextDelta::ToolCallFinished fills tool_calls in index order; argument chunks and starts are informational here, since the finished call carries the reassembled form. A call whose finish never arrived (the stream died mid-call) leaves no trace — a half-finished call is not a call the tool loop may run.
• TextDelta::Usage is last-wins, whole replacement.
• TextDelta::Finish supplies model (empty when the stream ended without one).
• json is always None: structured output is a complete feature — the parsed value comes from validating the whole answer against the prompt’s schema, which a stream that relayed itself away never promised. A streaming caller wanting a value parses and validates the reassembled text itself.

Implementations

impl CompletionBuilder

pub fn push(&mut self, delta: &TextDelta)

Folds one delta in. Cheap; call it for every item the stream yields.

pub fn finish_reason(&self) -> Option<&FinishReason>

Why the stream ended, where it sent a Finish — None for a stream that is still open or died without one.

pub fn finish(self) -> Completion

The completion the deltas add up to: text concatenated, tool calls from their finishes in index order, usage last-wins, model from the Finish, json None (see the type’s docs).

Trait Implementations

impl Debug for CompletionBuilder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for CompletionBuilder

fn default() -> Self

Returns the “default value” for a type.