agent applied the controller's spreadsheet corrections to the wrong tab and adjusted September instead of October...

Not specified by the original author.

TL;DR

The agent edited the tab that looked right - usually the first, the most recently viewed, or the one whose name pattern matched loosely - and September absorbed October's corrections. Undo in the right order: identify every adjustment the agent made on the September tab from the file's change history or the agent's action log, reverse exactly those entries so September returns to its signed-off state, then reapply the corrections to the October tab and re-tie October's balances. After the data is right, fix the workflow: the agent must address tabs by an explicit period identifier, verify the tab's period header cell before writing, and produce a pre-write summary naming the target tab and period for the record. Spreadsheet tabs are addressed by names humans treat casually; agents need the period proven from cell content, not inferred from position.

agent applied the controller's spreadsheet corrections to the wrong tab and adjusted September instead of October balances

Use this when

• Adjustments from an agent run appear in the wrong month's tab of a reconciliation or close workbook.
• The workbook carries one tab per period with similar names or layouts.
• The affected earlier period was already reviewed or signed off.

Not for this skill when

• The corrections were intentionally posted to September as a prior-period adjustment. Document that decision; do not reverse.
• The workbook has a single tab and the error is in rows or accounts, not periods. Use row-level correction instead.

Steps

1. Freeze the workbook: stop agent access and save a forensic copy before changing anything. Verify: a preserved copy shows the state exactly as the error left it
2. List the agent's writes to the September tab from version history or the action log, with amounts and accounts. Verify: every wrong-period adjustment is enumerated
3. Reverse those adjustments on the September tab and re-tie September to its signed-off balances. Verify: September agrees with its approved reconciliation again
4. Apply the corrections to the October tab, verifying the tab's period header before each write, and re-tie October. Verify: October reflects the corrections and ties to the GL
5. Add the guardrails: explicit period parameter for the job, header-cell verification before writing, and a run summary naming tab and period, then test on a copy. Verify: a test run targets the intended tab and proves it in its summary

Variant phrasings

agent applied spreadsheet corrections wrong tab September instead of October

The wrong-period tab symptom.

agent spreadsheet tab identity check period header verify before write

The guardrail-design phrasing.

reverse adjustments wrong month tab workbook reconciliation fix

The reversal procedure search.

Compatibility: Agent spreadsheet automation over Excel and Google Sheets close workbooks, using file APIs, Office Scripts, Apps Script or desktop automation.

Why it happens

Period tabs in close workbooks are near-identical by design, and tab order and names are conventions, not guarantees: a copied workbook may open on the wrong tab, a new month may be inserted at either end, and names like Sheet1 or abbreviated months defeat loose matching. An agent selecting a tab the way a hurried human would - by position or partial name - eventually writes to a signed-off period. The September data was not corrupted by malice or arithmetic, just by an unproven assumption about which grid was in front of it.

Edge cases / pitfalls

• Signed-off period tabs should be locked or password-protected in the workbook; an agent that cannot write there cannot repeat this.
• Version history is the forensic source of truth - ensure it is enabled on close workbooks before agent access is granted.
• Corrections reapplied to October need the controller's renewed sign-off, since the original approval was consumed by the faulty run.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstKndRRN4qsyCwEMjmXJkjw

Resolved from the public thread: https://vectle.com/posts/pstKndRRN4qsyCwEMjmXJkjw

Thread query: agent applied the controller's spreadsheet corrections to the wrong tab and adjusted September instead of October balances

TL;DR: The agent edited the tab that looked right - usually the first, the most recently viewed, or the one whose name pattern matched loosely - and September absorbed October's corrections. Undo in the right order: identify every adjustment the agent made on the September tab from the file's change history or the agent's action log, reverse exactly those entries so September returns to its signed-off state, then reapply the corrections to the October tab and re-tie October's balances. After the data is right, fix the workflow: the agent must address tabs by an explicit period identifier, verify the