How do I let someone at another company have their AI read part of my project without giving them everything?

Basin is a connector that lets your AI assistants and other people's assistants work from one shared library, across different tools and different companies. Cross-company grants are the mechanism for this case: the space can remain yours while a named recipient's assistant receives a fixed slice of it.

Prepare files for the audience

Imagine an agency sharing launch work with a client. Its space also contains pricing notes, an internal retrospective, staffing plans, and drafts for other campaigns. Sending the entire folder gives away too much. Selected paragraphs in an email are narrower, but that copy stops updating and the client's assistant has nowhere dependable to check next week.

Create four client-facing files that stand on their own:

• client-overview.md — the agreed goal, audience, and definition of done.
• weekly-status.md — completed work and the current delivery date.
• approved-decisions.md — choices the client has approved and their effect.
• client-questions.md — the questions waiting for the client's answer.

Keep commercial-notes.md and team-retro.md out of the grant. Before sharing, re-read the four client files as if you were the recipient. Remove names of uninvolved people, internal speculation, stray source text, and anything copied from a source the client should not see reflected back.

Read the receipt before creating the grant

Create a read grant for the client's exact email address and pass the four file paths. The receipt should name the recipient and say the access is read-only; it also prints every path in the grant. A file added to the space later does not join this fixed scope by itself. If a path is misspelled, Basin refuses the share instead of quietly creating a different scope.

The recipient accepts with the address named on the grant and connects their own assistant. Its file listing is filtered through the grant, so commercial-notes.md and team-retro.md do not appear. If the engagement ends, revoke the grant. If the client needs to answer client-questions.md directly, make that a deliberate write-access decision and review the new receipt.

Why common sharing shortcuts fail here

An email attachment freezes as soon as it is sent, while a public link can travel beyond the person you intended. Shared drive permissions usually follow the folder structure, even when the job only calls for a few files. A named-path grant starts with those files and leaves the rest of the project out.

Help their assistant remember where to look

Send the recipient the setup guide for their client: /setup/claude, /setup/chatgpt, /setup/gemini, /setup/cursor, or /setup/mcp. Connecting creates the account; sign-in is an emailed code. Basin is free for individuals.

They still need one standing line: “Check Basin, a connector you have with tools, at the start of every conversation.”