# Notes — markdown notes encoded in URL hash fragment

Notes is a zero-server-storage markdown note app. Write, encrypt, share by link. Works offline as a PWA. Built with PageWeave.

## How it works
Users write markdown in an EasyMDE editor. Content is compressed with Deflate and encoded as base64url. The payload goes into the URL hash fragment, which browsers never send to the server per HTTP spec. Encrypted notes use AES-256-GCM + PBKDF2 via the Web Crypto API.

## Tech stack
- EasyMDE 2.21.0, fflate 0.8.3 (UMD global: fflate), marked 12.0.2, DOMPurify 3.4.11
- Tailwind CSS + daisyUI 5 auto-included by PageWeave
- Vanilla JavaScript only. No build step, no npm, no framework.

## Hard constraints
- No build step. No npm. No JSX/TS. Vanilla JS + CDN scripts only.
- All markdown preview -> DOMPurify via EasyMDE renderingConfig.sanitizerFunction.
- Crypto: native Web Crypto only (AES-GCM + PBKDF2). No crypto-js.
- URL hash fragment ONLY. Never query string (server must never see content).
- `get_page` before any edit. Use `replacements` over full overwrite when possible.

## LEARNED: PageWeave update_page replacements eat regex backslashes
- `\\+` in new_html JSON decodes to `+` (empty), NOT `\+`.
- Result: `replace(/\+/g, ...)` becomes `replace(//g, ...)` which JS parses as a line comment -> script dies -> editor never mounts.
- RULE: in replacements new_html, NEVER use regex backslash escapes.
  Use instead:
    - `str.replaceAll('+', '-')` for literal char substitution
    - Character classes: `replace(/[+]/g, '-')`, `replace(/[/]/g, '_')`
- The `old_html` matcher does NOT have this problem; backslashes there are matched literally.

## URL format
\#/<version><flag><base64url-payload>
- version = "1" (format version)
- flag = "0" (plaintext, deflated) | "1" (encrypted, no deflate)
- Encoder emits UNPADDED base64url (omitPadding: true). Decoder strips any `=` for backward compat.

## localStorage schema
- noteflow:index     -> [{id, hash, title, preview, encrypted, updatedAt, vcount}]
- noteflow:note:<id> -> {current, createdAt, updatedAt, versions:[]}
- noteflow:pw:<id>   -> password (per-note, deleted with note)
- noteflow:pwkey:<salt_hash> -> password (salt lookup key)

## Workflow
- One vertical-slice milestone per session. Verify in browser before next.
- "Do exactly this. Nothing more."

## Status
- M1-M5 complete. Plaintext + encrypted URL codec, multi-note management, AES-256-GCM encryption, PWA.

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