Function deriveAgentSteps

frontend/src/components/timeline/AgentTracePanel.tsx:884–1085

(parts: AgentTraceChunk[])

}

function deriveAgentSteps(parts: AgentTraceChunk[]): AgentDerivedStep[] {
  if (!parts.length) {
    return [];
  }

  interface Snapshot {
    id?: string;
    hasReasoning: boolean;
    step: AgentDerivedStep;
  }

  const snapshots: Snapshot[] = [];
  const snapshotById = new Map<string, Snapshot>();
  const steps: AgentDerivedStep[] = [];

  const ensureDateMs = (iso?: string) => {
    if (!iso) return undefined;
    const value = new Date(iso).getTime();
    return Number.isNaN(value) ? undefined : value;
  };

  const createSnapshotStep = ({
    toolCallId,
    toolName,
    input,
    timestamp,
    sequence,
  }: {
    toolCallId?: string;
    toolName?: string;
    input?: unknown;
    timestamp: string;
    sequence: number;
  }): Snapshot => {
    const step: AgentDerivedStep = {
      key: toolCallId ? `tool-${toolCallId}` : `tool-${sequence}`,
      actions: [],
      observations: [],
      toolCallId,
      toolName,
      toolInput: input ?? null,
      toolOutput: undefined,
      timestamp,
      sequence,
      startedAt: timestamp,
      isComplete: false,
    };
    const snapshot: Snapshot = { id: toolCallId, step, hasReasoning: false };
    snapshots.push(snapshot);
    if (toolCallId) {
      snapshotById.set(toolCallId, snapshot);
    }
    steps.push(step);
    return snapshot;
  };

  const findFallbackSnapshot = () => snapshots.find((candidate) => !candidate.hasReasoning);