Dear Mann

A private diary that writes back. You choose who you need right now (Dear diary, Best friend, Spouse, Mom, or "You decide"), write, and get a short reply in that voice, ending with a handwritten "I know."

This repository is the web version, ready for Vercel.

How it works

Part	What it does
index.html	The whole app (built from src/iknow.html).
standalone.js	Lets the app run on its own website: replies go through /api/sample, exports become normal downloads, and the diary is stored in the phone's own browser.
api/sample.js	A Vercel serverless function. It adds your Anthropic API key and calls the Claude Messages API. It stores and logs nothing.
vercel.json	Security headers. No build step is needed.

Where the diary lives: only in the browser on the phone that uses it (localStorage). There is no account and no database. Clearing browser data or switching phones loses the diary, so users should use Settings → Export my diary now and then.

What leaves the phone: only the text needed to write a reply, sent through /api/sample to Anthropic's API.

Setup on Vercel

Add these under Project → Settings → Environment Variables, then redeploy:

Variable	Required	Purpose
ANTHROPIC_API_KEY	Yes	Your key from console.anthropic.com. Without it, replies show "Replies aren't switched on yet".
IKNOW_ACCESS_CODE	Recommended	An invite code. When set, each phone must enter it once before replies work, so strangers who find the link can't spend your API credit.
IKNOW_DEVICE_SECRET	Recommended	Turns on phone-specific codes (replaces IKNOW_ACCESS_CODE). A long phrase only you know, at least 20 characters. Changing it switches off every phone's code at once.
IKNOW_REQUEST_WHATSAPP	With phone codes	Your WhatsApp number with country code, e.g. 919800000000. The app's "Request a code" button opens WhatsApp to this number with the phone's ID filled in.
IKNOW_REQUEST_EMAIL	Optional	An email address for code requests, as well as or instead of WhatsApp.
IKNOW_REVOKED_DEVICES	Optional	Link IDs or phone IDs to switch off, separated by commas, e.g. X9A5-Y3RJ, NY4C-ECWJ.
BLOB_READ_WRITE_TOKEN	For sign-in links	Added automatically when you connect a Vercel Blob store to the project (Storage → Create → Blob).
ANTHROPIC_WORKSPACE_ID	Only if needed	Needed only when your API key isn't tied to a workspace (Anthropic then says the request "must include the anthropic-workspace-id header"). Copy the ID from console.anthropic.com → Workspaces. Easier: create the key inside a workspace instead.
ANTHROPIC_MODEL	No	Model for replies. Default claude-sonnet-5-5.
ANTHROPIC_MODEL_QUICK	No	Model for quick tasks (picking a voice, style summaries). Default claude-haiku-5-5.

The function also limits each IP address to 20 requests a minute (best effort).

Owner-approved access (recommended, fully automatic)

Access is managed by a small service (Supabase Edge Function iknow-access, source in supabase/functions/iknow-access/) with its own private database schema iknow.

1. Owner account. The first time, open /owner and create your username and password. To prove it's you, it checks your current IKNOW_ACCESS_CODE (read from your phone automatically if you've used the app there). Only a PBKDF2 hash of the password is stored.
2. People ask from the app. A new phone sees "Dear Mann is invite-only", types their name, and taps Ask for access (optionally nudging you on WhatsApp if IKNOW_REQUEST_WHATSAPP is set).
3. You tap Approve, Decline, Switch off or Turn back on on /owner. It takes effect on that phone within about 30 seconds. No Vercel settings, no redeploys.

Once the owner account exists, the shared invite code no longer gives anyone access; it is only used as a fallback if the access service is unreachable. Stored per phone: a hash of a random token made by that browser, the name they typed, status and dates. No diary text.

One-time sign-in links (alternative)

Needs IKNOW_DEVICE_SECRET and a Vercel Blob store connected to the project.

1. Open /owner, enter your secret, tap Make a sign-in link, then Copy a message to send.
2. The person opens the link in Chrome or Safari (the page warns them if they are inside WhatsApp's own browser) and taps Activate on this phone.
3. That browser is now signed in. The link is used up: opened anywhere else it says "already been used". Unused links expire after 7 days. Opening a link without tapping Activate uses nothing.

The Blob store holds only iknow-used/<linkId> markers. No names, no diary text. Replies are checked by signature, so there is no lookup per reply.

Phone-specific codes

With IKNOW_DEVICE_SECRET set, every phone (or browser) gets its own ID, like NY4C-ECWJ, the first time it asks for a reply.

1. The person taps Request a code on WhatsApp. WhatsApp opens with their phone ID filled in.
2. You open /owner on this site (e.g. know-zeta.vercel.app/owner), enter your secret and their phone ID, and get their code, e.g. 772M-GECM.
3. You send the code back. It works only on the phone with that ID; on any other phone it is refused.

No database is used: a code is a signature of the phone ID made with your secret, so the server can check it without storing anything. The owner page works the code out in your own browser and sends nothing anywhere.

A new browser, a private window, or clearing browser data gives that phone a new ID, so it needs a new code (its old diary is gone in that case anyway).

Editing the app

Edit src/iknow.html, then rebuild index.html:

python3 build.py

src/iknow.html is the same file that runs inside Claude as an artifact. build.py only adds the standalone adapter and web-accurate privacy wording.

Help lines shown in the app

Tele-MANAS 14416 / 1-800-891-4416 (India, free, 24×7) and emergency 112. Dear Mann is not therapy, medical, legal or emergency advice.