The Tunnel

Stop writing emails. Start sending documents. Let the AIs coalesce.

The problem with email

You write an email. It's flat text. No structure. No headers. No tables. Nested reply chains with > quotes six levels deep. Your colleague reads it, maybe. Their brain parses the important parts from the filler. They write back. More flat text. More nesting. Six months later someone searches their inbox for "what did we decide about the migration" and finds forty threads with the same subject line and no answer.

Now add AI to both ends. You have Claude draft the email body. Your colleague has their AI read the chain and draft a reply. Both AIs are parsing broken formatting, forwarded signatures, legal disclaimers, and HTML that got mangled by Outlook. The information is in there somewhere. Neither AI can find it cleanly because the format wasn't designed for machines. It was barely designed for humans.

The fix

Stop putting the content in the email body. Put it in a markdown file (a plain text file with simple formatting — # for headings, - for bullet points) and attach it.

Markdown has structure. Headers, bullet points, tables, code blocks, numbered lists. When an AI reads a markdown file, it gets clean, parseable content it can reason about. When it reads a forwarded email chain, it gets soup.

The email becomes the envelope. The markdown file is the letter. The envelope says who it's from, who it's to, and carries one critical addition: an ID in the subject line.

RE: Migration Status [ID:mig-2026-04-10-003]

The ID

Every AI assistant available today is stateless. Claude doesn't remember your last conversation. ChatGPT doesn't remember last week's thread. Every session starts from zero. That's not a bug anyone is going to fix soon — it's an architectural property of how these systems work.

The ID solves this. It's a shared reference number that any AI on any end of the conversation can use to find prior context. When your colleague's AI sees [ID:mig-2026-04-10-003], it searches their files for every previous attachment with that ID. It reads them in order. It reconstructs the full conversation history from the documents themselves. No memory required. The markdown files are the memory.

The format doesn't matter much. Pick something readable:

[ID:mig-2026-04-10-003]     ← project-date-sequence
[ID:budget-review-q2-007]   ← topic-period-sequence
[ID:kas-audit-12]            ← system-type-sequence

Keep them consistent within a thread. That's all the protocol needs.

This is not two-ended

An email thread can have two people. Or five. Or twenty. The tunnel works the same way regardless. Everyone attaches markdown. Everyone uses the same ID. Every AI on every end can read every prior attachment and reconstruct the full picture.

Picture a project with three teams. Engineering sends a status markdown. Product reads it, has their AI draft a response with questions, attaches it. Design reads both, has their AI draft a third document addressing the questions and adding constraints. All three documents carry the same ID. Any AI joining the conversation late can read all three and synthesize.

This is how stateless systems achieve continuity at scale. Not through memory. Through documents. The conversation is the collection of files, not the email thread. The email thread is just the delivery mechanism.

Why this works

Structure survives forwarding

Email bodies get mangled by every client that touches them. Outlook reformats HTML. Gmail strips styling. Mobile clients collapse quotes. Markdown files arrive exactly as they were sent. The recipient's AI reads the same document the sender's AI wrote.

Documents are artifacts

An email body lives in an inbox. A markdown file lives on a filesystem. It can be saved, compared version by version, searched, and organized. Six months later, the file is still there, still structured, still readable. The email thread is buried under a thousand other threads.

Disclosure is built into the format

Nobody hand-writes a perfectly structured markdown file with headers, tables, and bullet points. The format itself signals "an AI helped produce this." That's not a problem. That's a feature. It normalizes AI-assisted communication and makes the human's role clear: they directed, they reviewed, they approved, they sent. The AI drafted. Everyone knows. Nobody's pretending.

Each AI gets smarter per round

On the first exchange, each AI has one document. By the fifth exchange, each AI has five documents of structured context — all identified, all ordered, all parseable. The conversation gets more coherent over time, not less, because the context accumulates in files instead of decaying in nested quotes. The AIs coalesce around the problem because the documents give them everything they need to do it.

How to start

Next time you need to send a status update, a proposal, or a summary: tell your AI to write it as a markdown file instead of an email body.
Attach the file. Keep the email body to one sentence: "Attached: migration status update. Let me know if questions."
Add an ID to the subject line. Anything consistent. [ID:whatever-makes-sense].
Tell the recipient. "If you feed this to your AI, it can draft a response. Same format, same ID, attach it back." You just opened a tunnel.
On the next round, tell your AI to read all attachments with that ID before drafting a response. It will synthesize the full history and produce a document that builds on everything that came before.

You don't need both sides to use AI. If your colleague reads the markdown with their eyes and replies in plain text, that's fine. The structured document is still better than an email body. The tunnel works at any speed, with any number of participants, with or without AI at every node. It just gets better when both sides have it.

What this really is

It's a protocol. Not software. Not a platform. A way of communicating where the content is structured, the context is identified, and the transport doesn't matter. Email, Slack, Teams, carrier pigeon — the markdown file and the ID are the protocol. Everything else is plumbing.

The internet was built on protocols like this. SMTP (email delivery), HTTP (web pages), FTP (file transfer) — simple rules about how to format a message so that any system on any end can read it. The Tunnel is the same idea applied to AI-assisted human communication: structure the document, identify the thread, and let any AI on any end reconstruct the conversation from the artifacts.

We've been writing emails for thirty years. The format hasn't evolved. The tools reading them have. Time to give those tools something they can actually work with.

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Disclosure: This page was generated by Claude (Anthropic) under Bill's direction. The Tunnel concept is Bill's. If you implement it and it changes how your team communicates, tell him — the email is in the book page.