Stream the spans of a single trace as CSV or JSONL (sync export)

Cursor-streamed synchronous export of every span belonging to the trace identified by trace_id. trace_id is required — the batch “all traces” export path was removed because it was too expensive to support at hypertable scale. Callers needing trace- level analytics should use GET /v1/traces for paginated listing and call this endpoint per trace.

Rows are written directly to the response body — never buffered — and capped per plan (Starter: 100, Pro/Team/Business: 5000, Enterprise: unlimited). Hitting the cap sets X-TruLayer-Truncated: true; the payload is complete up to that row.

CSV columns (in order): trace_id, span_id, name, type, model, created_at, duration_ms, prompt_tokens, completion_tokens, cost_usd, trace_input, trace_output, span_input, span_output, error. span_id is the unique identifier for the span (renamed from id). trace_input is the parent trace’s input text joined onto every span row. span_input is the span’s own input text. trace_output and span_output are the parent trace’s and span’s output payloads respectively, so a single download carries the full input/output context for both the trace and each span.

JSONL emits one JSON object per line with the same keys.

The Content-Disposition filename is spans-<trace-prefix>-YYYY-MM-DD.{csv,jsonl}.