Distillation

Date: Sep 16, 2026

• 🟡 (19:46) User supplied a continuation of packages/gateway/src/pipeline.ts covering approximately lines 8391-9027 of the Responses stream lifecycle implementation.
• 🟡 (19:46) The implementation rejects an invalid initial function-call status with exact error "invalid initial Responses function status".
• 🟡 (19:46) Responses output-item reconciliation derives identities from both item.id and item.call_id, compares them against identities already stored in state.rawItems, and detects overlap when any new identity is present in the existing identity set.
• 🟡 (19:46) Per-item lifecycle state includes a reasoning: new Map() collection and recognizes reasoning summary content type "summary_text".
• 🟡 (19:46) The implementation enforces event ordering and throws Responses ${event} arrived before output_item.added for index ${outputIndex} when a dependent event precedes output_item.added.
• 🟡 (19:46) Content lifecycle distinguishes "reasoning_text" as partKind/kind "reasoning" and other handled content as kind "message", tracks authoritativeValue and initialValue, and rejects malformed deltas with invalid Responses ${event} delta.
• 🟡 (19:46) Reasoning-summary lifecycle tracks finalValue, valueDone, partAdded, and partDone; duplicate summary completion is rejected with duplicate Responses reasoning summary completion for index ${outputIndex}:${summaryIndex}.
• 🟡 (19:46) Function-call argument completion validation throws exact error "invalid Responses function arguments completion" and handles events whose names begin with "response.function_call_arguments".
• 🟡 (19:46) output_item.done validation has type-specific branches for declared types "function_call" and "message"; it rejects a non-string item.status and rejects message content whose completed type differs from its prior lifecycle type with Responses output_item.done changed content type for index ${outputIndex}:${contentIndex}.