Uploads

How to analyze CSV and XLSX files with the Stackless Agent, compare them with warehouse data, and what the limits are.

What uploads are for

Uploads let you bring a CSV or XLSX file into an Agent conversation and analyze it alongside your governed data.

Use uploads for:

One-time spreadsheet analysis.
Comparing a file to warehouse data, such as targets against actuals.
Matching a list against an existing source, such as checking which customer IDs exist.
Sharing a mapping table or business-rule sheet the Agent should follow in the conversation.

Uploads stay with the conversation. They are not written to the warehouse, and they cannot feed dashboards, which always read governed Semantic Models. Data that should drive recurring reporting belongs in a connected source.

Upload a file

Open Agent.
Click the paperclip (or + > Upload file) and choose a .csv or .xlsx file.
The file appears above the message box with its sheet count and size. It will be sent with your next message.
Describe what the file is and how the Agent should use it, then send.

If no conversation is open, uploading starts a new conversation named after the file. Sent files are kept with the conversation; click the file chip to download it again.

Tell the Agent what the file is

Always say what the file represents and how it relates to your existing data:

This workbook has our Q4 2026 channel targets. Compare October net revenue by channel against the October targets and flag channels behind pace.

This CSV is a one-time list of customers from a trade show. Match it to existing customers by email and show the ones we don't have.

If Stackless cannot tell whether a file is standalone data or should be matched to an existing source, it shows a reminder: "Mention whether this upload is seed data or should be matched to an existing source in your message."

What the Agent can do with an upload

Profile the file: sheets, columns, types, and sample rows.
Query the whole sheet with read-only SQL, for totals, filters, and group-bys.
Join the upload with warehouse tables, for example targets with actual revenue, using up to 50,000 upload rows.
Find the Catalog tables that best match the file's columns.
Produce table artifacts, briefs, finding cards, and comparison summaries from the results.

Limits

Limit	Value
File types	`.csv` and `.xlsx`
File size	10 MB per file
Workbook size	100 MB of sheet data once uncompressed
Staged files	10 waiting to be sent
Files per conversation	100
Rows joined with warehouse data	50,000

Files that are staged but never sent are removed after 24 hours.

Privacy and sensitivity

Treat uploads as data shared with your Stackless workspace. Avoid uploading direct personal identifiers or confidential files unless your organization has approved it. If a table artifact built from an upload includes sensitive columns, ask the Agent to mask them:

Create a table artifact from this upload, but mask the email and phone columns.

Troubleshooting uploads

Message	What to do
Only .csv and .xlsx uploads are supported.	Convert the file, for example save an `.xls` or `.numbers` file as `.xlsx`.
File is too large. The upload limit is 10 MB.	Remove unneeded columns or sheets, or split the file.
Upload is empty.	Check that the file has a header row and data.
Could not read workbook	Remove password protection and unusual workbook features, then save it again.
Too many pending uploads	Send or remove staged files before adding more.

If the Agent misunderstands the file, correct it in your next message, for example: "Column B is the target, not the actual."