Excel Author — Build auditable financial workbooks headless via openpyxl
Excel Author — Build auditable financial workbooks headless via openpyxl
Start with meaning, then move to detail.
This lesson explains Excel Author — Build auditable financial workbooks headless via openpyxl as part of getting started with Hermes correctly. You will learn what it does, when it matters, and the smallest safe test that proves it works.
If you are new, do not memorize names. Focus on three questions: what problem does this solve, what access does it need, and how can you verify the result?
For practice, inspect the first example, identify its effects, run it on test data, and compare the result with the source claim.
For advanced readers, inspect Skill metadata, Reference: full SKILL.md, Output contract, then verify failure modes and version compatibility.
No prior experience is required; follow the steps on a safe test setup first.
A clear outcome before you read.
- Understand Excel Author — Build auditable financial workbooks headless via openpyxl without assumed prior knowledge.
- Separate the source description from what still needs testing in your environment.
- Read the first command and identify its inputs and outputs before copying it.
Short definitions before the details.
- Skill
- An instruction bundle that teaches Hermes a repeatable workflow without necessarily adding an external service.
Build auditable financial workbooks headless via openpyxl
What does the source say, and in what order?
- 01Skill metadata
Start here to understand the core idea or structure.
- 02Reference: full SKILL.md
Read this after the foundation, then connect it to the previous step.
- 03Output contract
Read this after the foundation, then connect it to the previous step.
- 04Setup
Read this after the foundation, then connect it to the previous step.
- 05Core conventions (non-negotiable)
Read this after the foundation, then connect it to the previous step.
- 06Blue / black / green cell color
Read this after the foundation, then connect it to the previous step.
- 07Formulas over hardcodes
Read this after the foundation, then connect it to the previous step.
- 08Named ranges for cross-sheet references
Read this after the foundation, then connect it to the previous step.
- 09Balance checks tab
Read this after the foundation, then connect it to the previous step.
- 10Cell comments on every hardcoded input
Finish here to verify the result and special cases.
Copy only after you understand the effect.
pip install "openpyxl>=3.0"The only hardcoded numbers permitted:
1. Raw historical inputs (actual revenues, reported EBITDA, etc.)
2. Assumption drivers the user is meant to flex (growth rates, WACC inputs, terminal g)
3. Current market data (share price, debt balance) — with a cell comment documenting source + date
If you catch yourself computing a value in Python and writing the result, stop.
### Named ranges for cross-sheet references
Use named ranges for any figure referenced from another sheet, a deck, or a memo.### Balance checks tab
Include a `Checks` tab that ties everything and surfaces TRUE/FALSE:
- Balance sheet balances (assets = liabilities + equity)
- Cash flow ties to period-over-period cash change on the BS
- Sum-of-parts ties to consolidated totals
- No rogue hardcodes inside calc ranges
Example:Read the first command and identify its inputs and outputs before copying it.
Match every command to your installed Hermes version, review the files and accounts it can reach, and use non-sensitive data for the first test. If this explanation differs from the source, the official source wins.