51 lines
2.1 KiB
TypeScript
51 lines
2.1 KiB
TypeScript
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/**
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* Helpers for detecting Vercel AI SDK internal stream-state errors.
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*
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* Background — issue #1101 follow-up:
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*
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* When a third-party Anthropic-compat backend (DeepSeek's
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* `deepseek-v4-flash` is the canonical offender) streams thinking
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* deltas without first emitting a `reasoning-start` content-block
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* signal, the Vercel AI SDK's reasoning state machine has nothing
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* registered for the incoming `part.id` and enqueues an
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* `error` chunk on `stream` with the text
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* `reasoning part <id> not found` — once per orphan delta. The
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* analogous error exists for text parts.
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*
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* These chunks are *internal SDK bookkeeping noise*, not user-facing
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* errors. Worse, treating them as real errors (adding a placeholder
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* assistant message for each) breaks tool_use/tool_result contiguity
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* on the next turn: the Anthropic message grouper splits the
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* tool-result `role: 'tool'` messages from their parent tool_use
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* `role: 'assistant'`, and the backend responds with
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* `400 messages.N: tool_use ids were found without tool_result blocks
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* immediately after`.
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*
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* Filtering these specific errors at the chunk-handler boundary
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* stops the cascade: the orphan deltas are dropped silently (the SDK
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* continues processing other chunks), no fake assistant messages
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* land in history, and the next turn's request stays well-formed.
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*/
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const STATE_ERROR_PATTERN = /^(?:reasoning|text)\s+part\s+\S+\s+not\s+found$/i;
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/**
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* Return true if `error` is one of the SDK's internal stream-state
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* tracking errors (e.g. an out-of-order reasoning delta). Accepts
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* the loose `unknown` shape that comes off the chunk so callers
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* don't need to narrow upstream.
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*/
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export function isSdkStreamStateError(error: unknown): boolean {
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if (typeof error === 'string') {
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return STATE_ERROR_PATTERN.test(error.trim());
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}
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if (error instanceof Error) {
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return STATE_ERROR_PATTERN.test(error.message.trim());
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}
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if (error && typeof error === 'object' && 'message' in error) {
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const msg = (error as { message?: unknown }).message;
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if (typeof msg === 'string') return STATE_ERROR_PATTERN.test(msg.trim());
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}
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return false;
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}
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