Function handleChatCompletion

src/proxy.ts:428–504

(
  body: ChatCompletionRequest,
  accessToken: string,
)

}

function handleChatCompletion(
  body: ChatCompletionRequest,
  accessToken: string,
): Response | Promise<Response> {
  const { systemPrompt, userText, turns, toolResults } = parseMessages(body.messages);
  const modelId = body.model;
  const tools = body.tools ?? [];

  if (!userText && toolResults.length === 0) {
    return new Response(
      JSON.stringify({
        error: {
          message: "No user message found",
          type: "invalid_request_error",
        },
      }),
      { status: 400, headers: { "Content-Type": "application/json" } },
    );
  }

  // bridgeKey: model-specific, for active tool-call bridges
  // convKey: model-independent, for conversation state that survives model switches
  const bridgeKey = deriveBridgeKey(modelId, body.messages);
  const convKey = deriveConversationKey(body.messages);
  const activeBridge = activeBridges.get(bridgeKey);

  if (activeBridge && toolResults.length > 0) {
    activeBridges.delete(bridgeKey);

    if (activeBridge.bridge.alive) {
      // Resume the live bridge with tool results
      return handleToolResultResume(activeBridge, toolResults, modelId, bridgeKey, convKey);
    }

    // Bridge died (timeout, server disconnect, etc.).
    // Clean up and fall through to start a fresh bridge.
    clearInterval(activeBridge.heartbeatTimer);
    activeBridge.bridge.end();
  }

  // Clean up stale bridge if present
  if (activeBridge && activeBridges.has(bridgeKey)) {
    clearInterval(activeBridge.heartbeatTimer);
    activeBridge.bridge.end();
    activeBridges.delete(bridgeKey);
  }

  let stored = conversationStates.get(convKey);
  if (!stored) {
    stored = {
      conversationId: deterministicConversationId(convKey),
      checkpoint: null,
      blobStore: new Map(),
      lastAccessMs: Date.now(),
    };
    conversationStates.set(convKey, stored);
  }
  stored.lastAccessMs = Date.now();