continueRun method

Future<AgentRun> continueRun(List<ChatMessage> transcript)

Continues an existing transcript (e.g. from a previous AgentRun).

Implementation

Future<AgentRun> continueRun(List<ChatMessage> transcript) async {
  final messages = [...transcript];
  final steps = <AgentStep>[];
  var input = 0;
  var output = 0;
  var cached = 0;
  final byName = {for (final t in tools) t.name: t};

  for (var round = 0; round < maxSteps; round++) {
    final response = await model.completeWithTools(
      messages,
      system: system,
      maxTokens: maxTokens,
      tools: tools,
    );
    input += response.usage?.inputTokens ?? 0;
    output += response.usage?.outputTokens ?? 0;
    cached += response.usage?.cachedInputTokens ?? 0;

    if (response.toolCalls.isEmpty) {
      messages.add(ChatMessage.assistant(response.text));
      return AgentRun(
        answer: response.text,
        steps: steps,
        transcript: messages,
        usage: ChatUsage(
          inputTokens: input,
          outputTokens: output,
          cachedInputTokens: cached,
        ),
      );
    }

    messages.add(
      ChatMessage(
        ChatRole.assistant,
        response.text,
        toolCalls: response.toolCalls,
      ),
    );
    final results = <ToolResult>[];
    for (final call in response.toolCalls) {
      final tool = byName[call.name];
      AgentStep step;
      if (tool == null) {
        // Tell the model rather than failing the run: it can pick a real
        // tool on the next round.
        step = AgentStep(
          call: call,
          result:
              'No tool named "${call.name}". Available: '
              '${tools.map((t) => t.name).join(', ')}.',
          isError: true,
        );
      } else {
        try {
          step = AgentStep(call: call, result: await tool.run(call.input));
        } catch (e) {
          step = AgentStep(call: call, result: '$e', isError: true);
        }
      }
      steps.add(step);
      onStep?.call(step);
      results.add(
        ToolResult(id: call.id, content: step.result, isError: step.isError),
      );
    }
    messages.add(ChatMessage.toolResults(results));
  }

  return AgentRun(
    answer: '',
    steps: steps,
    transcript: messages,
    usage: ChatUsage(
      inputTokens: input,
      outputTokens: output,
      cachedInputTokens: cached,
    ),
    exhausted: true,
  );
}