Scale-Out

Every other folder in this cookbook labels a handful of rows in a synchronous loop; this folder is what changes when the row count grows five zeros. The labeling call itself stays exactly what _01_text_classification/ does - one reused agent, a Pydantic schema, one label per row - and everything added here is harness: an async fan-out with a bounded semaphore, a checkpoint that makes interruption cheap, and token accounting that prices the job before you commit to it.

Files

• basic.py — async fan-out. One reused agent labels 30 short reviews via agent.arun under asyncio.Semaphore(8), with a progress line every 10 rows. Per-row latency is timed inside the semaphore, so the sequential estimate (rows x mean latency) and the wall clock printed at the end come from the same run - the speedup is a measured number (7.0x at concurrency 8 in our test), not a claim.
• resumable.py — adds checkpointed resume. Each finished row is appended to data/generated/labels.jsonl the moment it lands, keyed by row id; on startup, done ids are loaded and skipped. The demo interrupts itself after 15 rows, then reruns with the full list and prints skipped versus newly labeled. Kill a 100k-row job at row 60k and the rerun does 40k rows of work.
• with_cost_tracking.py — adds token and dollar accounting from run.metrics: per-row averages, run totals, the cost of the run at Gemini list prices, and the projection to 100k rows. On a reasoning model the thinking tokens dominate the bill: ~149 reasoning tokens per row versus ~6 output tokens in our run.

Example rows

Rows written by resumable.py (the output file doubles as the checkpoint, so id is the resume key):

{"id": "r01", "text": "Absolutely love this blender, it crushes ice in seconds.", "label": "positive"}
{"id": "r15", "text": "Returned it immediately, the fan noise is unbearable.", "label": "negative"}
{"id": "r21", "text": "The box contains the charger, a cable, and a manual.", "label": "neutral"}

When to use

• Running any folder's labeling task at real dataset size. The harness never looks inside the per-row call: swap in the schema and instructions from _03_text_extraction/, _15_document_classification/, _17_llm_as_judge/, or any sibling folder and the fan-out, checkpoint, and accounting are unchanged.
• Jobs long enough to be interrupted - by a crash, a rate limit, or a laptop lid: resumable.py.
• Pricing a job before committing to it: with_cost_tracking.py. When the job is not latency-sensitive, provider batch APIs run the same model at roughly 50% of interactive list prices - at 100k rows that was the difference between $142 and $71 in our measured run.
• Filtering, deduplicating, and packaging what you labeled: _22_dataset_curation/. Its judge gate is the same shape of per-row call, so it scales out with this exact harness too.

Run

python cookbook/data_labeling/_26_scale_out/basic.py
python cookbook/data_labeling/_26_scale_out/resumable.py
python cookbook/data_labeling/_26_scale_out/with_cost_tracking.py

Requires GOOGLE_API_KEY.