Research the question in research-workbook-brief.md and create a polished local XLSX workbook for Kingy.ai readers. Use current official OpenAI documentation as the evidence source. Do not use Kingy.ai articles, search-result snippets, social posts, or unsourced model knowledge as evidence.

Create these sheets:
1. Read me: scope, run date, evidence rules, and material limitations.
2. Model comparison: one clearly labeled column per model and the required specifications as rows.
3. Capability matrix: the documented tools and workflow capabilities, with precise distinctions between shared capabilities and Astra-specific changes.
4. Cost calculator: editable workload inputs from the brief and formula-driven estimates for each model. Calculate only when rate definitions are complete and compatible; otherwise leave the result blank and explain why.
5. Sources: source title, publisher, page or section, URL, access date, model, fields supported, and conflict notes.

Use typed numeric values for token limits and prices, suitable number formats, frozen headers where useful, readable column widths, and restrained formatting. Keep formulas simple and auditable. Put source URLs in ordinary cells. Do not add decorative charts, invented confidence scores, or claims that the sources do not support.

Before finishing, inspect the key ranges and formulas, scan the workbook for spreadsheet errors, render every sheet for visual review, and correct any clipped text, unreadable columns, blank required sections, or formula errors. Save one XLSX file locally. Report the path, sources consulted, checks performed, unresolved conflicts, and any unavailable usage data. Do not upload the workbook, write to Google Drive or another external app, use a paid API, or publish anything.
