refactor(sse): split chatCore.ts pure helpers into chatCore/ modules (−561 LOC)

[diegosouzapw]

Objetivo

Encolhimento estrutural do maior god-file de hot-path do open-sse/: chatCore.ts 5980 → 5419 LOC (−561), extraindo 6 grupos coesos de helpers internos puros para módulos focados em open-sse/handlers/chatCore/, continuando o padrão de modularização #3598/#3821 (que já criou idempotency.ts/sanitization.ts/semanticCache.ts/memorySkillsInjection.ts).

Zero mudança de comportamento — todos os corpos foram movidos verbatim; as únicas edições são export, ajuste de path de import, remoção das defs + import-back, e 1 comentário.

Módulos novos (cada um com teste de seam dedicado)

Módulo	Funções	Teste de seam
chatCore/logTruncation.ts	capMemoryExtractionText, truncateChatLogText, cloneBoundedChatLogPayload, truncateForLog	chatcore-log-truncation.test.ts
chatCore/memoryExtraction.ts	extractMemoryTextFromResponse/RequestBody, resolveMemoryOwnerId	chatcore-memory-extraction.test.ts
chatCore/passthroughToolNames.ts	build/restore/merge ClaudePassthroughToolNames	chatcore-passthrough-tool-names.test.ts
chatCore/headers.ts	getHeaderValueCaseInsensitive (compartilhado — evita ciclo)	chatcore-headers.test.ts
chatCore/nonStreamingSse.ts	parse/convertNDJSON/normalize/terminal-detection SSE (8 fns)	chatcore-non-streaming-sse.test.ts
chatCore/upstreamTimeouts.ts	create*Error, readStreamChunkWithTimeout, computeBillableTokens, getExecutorTimeoutMs, normalizeExecutorResult, executeWithUpstreamStartTimeout	chatcore-upstream-timeouts.test.ts

A lição #3821 (a extração #3598 shipou um ReferenceError que nenhum teste pegou) motivou o teste de seam por módulo — incluindo cobertura das 2 funções mais complexas do nonStreamingSse (appendNonStreamingSseTerminalSignal stateful + parseNonStreamingSSEPayload).

Protocolo lossless (por commit)

Move-not-copy + git diff = só relocação + grep de símbolos + typecheck + lint + check:cycles + file-size encolhe (ratcheado p/ baixo). Nenhum módulo importa de volta de chatCore.ts (sem ciclo).

Verificação

• typecheck:core limpo · lint 0 errors · check:cycles OK · file-size sem --update PASSA (chatCore não cresceu, baseline ratcheado 5980→5419)
• test:unit → ℹ fail 0 (1 cancel de quota-spend-recorder = race do --test-force-exit sob carga, arquivo não-relacionado, passa isolado 5/5)
• test:vitest → 187/187
• 19 testes de seam (6 arquivos novos) verdes

Nota sobre #3501

Vários comentários do file-size-baseline.json adiavam "structural shrink of chatCore.ts tracked in #3501" — mas #3501 era o épico do providers/[id]/page.tsx (ProviderDetailPageClient.tsx), concluído (META ≤800, fase 1t) e fechado; nunca cobriu o chatCore. Este PR é esse shrink adiado; um comentário novo no baseline registra isso (sem reescrever os históricos).

Escopo / próximos

Fora deste PR (sub-projetos futuros): decompor a orquestração do handleChatCore; split do combo.ts; curadoria da lista mutate do Stryker.

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[gemini-code-assist]

Code Review

This pull request refactors chatCore.ts by extracting several helper functions into dedicated modules under open-sse/handlers/chatCore/ and adding corresponding unit tests under tests/unit/. The review feedback identifies a potential memory leak in upstreamTimeouts.ts where an anonymous event listener registered on signal inside abortPromise is not cleaned up after the promise race completes, and provides a suggestion to remove it in the finally block.

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[gemini-code-assist]

The anonymous event listener registered on signal inside abortPromise is never removed when the promise race completes. If signal is a long-lived object or if many requests share/re-use signals, this will cause a memory leak.

To prevent this, store a reference to the listener function and remove it in the finally block, similar to how abortListener and timeoutAbortListener are cleaned up.

  let abortPromiseListener: (() => void) | null = null;
  const abortPromise = new Promise<never>((_, reject) => {
    abortPromiseListener = () => reject(createAbortError(signal));
    signal.addEventListener("abort", abortPromiseListener, { once: true });
  });

  try {
    return await Promise.race([execute(combinedController.signal), timeoutPromise, abortPromise]);
  } finally {
    if (timeoutId) clearTimeout(timeoutId);
    if (abortListener) signal.removeEventListener("abort", abortListener);
    if (abortPromiseListener) signal.removeEventListener("abort", abortPromiseListener);
    if (timeoutAbortListener) {
      timeoutController.signal.removeEventListener("abort", timeoutAbortListener);
    }
  }