Always verify gateway changes with exhaustive, protocol-specific regression analysis

Before modifying gateway, streaming, recall, or continuation behavior, inspect the current implementation, adjacent tests, schemas, parsers, normalized types, builders, persistence, accumulators, retries, budgets, transactions, cancellation, cleanup, duplicated branches, and all callers. Trace item types, phase statuses, identities, indices, reconciliation, malformed events, terminal reconstruction, hidden data, and resource limits. Compare Anthropic, OpenAI Chat, Responses, Codex, Vertex, and Gemini semantics separately, including native and non-native modes. Ground conclusions in exact files, lines, symbols, searches, blame, commits, diffs, and regression cases; distinguish facts from inference. Make narrow, failing-first, test-backed changes covering failure, exhaustion, retries, aborts, leakage, lifecycle suppression, cleanup, and limits while preserving protocol, privacy, resource, transaction, rollback, identity, and terminal invariants.