Captured

Captured is a language learner's notebook built around an AI grammar tutor. You ask the tutor about the grammar of the language you are studying, in plain words and at your level, follow up in a conversation it remembers and can search, and save its answers as grammar rules. Those rules sit in one place with the rest of what you are learning, the words, phrases and verb conjugation tables you collect, linked to them, and flashcards built from it all come back when they are due. Every list is stored in Supabase and belongs to the account that saved it, so the same notebook is there on any browser or device.

It is live at https://definition-capture.vercel.app.

Why the AI is the core. Without the tutor this would be a vocabulary list, which any notebook or spreadsheet already is. What makes Captured worth using is the grammar discussion a learner otherwise needs a teacher or a forum for: a point explained plainly, in your own language or the one you are learning, the next question answered with the conversation in mind, and what came of it kept as a rule beside your words and phrases instead of being lost in a chat window. The tutor is a real model, called through OpenRouter from the server only; which one is named on the Tutor page.

The public landing page, for visitors who are not signed in:

Features

• Dashboard: what is due for review, progress so far, a word to test yourself on, and what was captured most recently.
• Vocabulary: words, definitions, references, up to five collections and a source, with search, a collection filter, sorting, and a flag for words whose definition is still to be written.
• Phrases: expressions with a literal meaning and a usage example, kept as their own list.
• Verb tables: a conjugation table per verb, with a column per tense, a row per person, a note against any row, and notes on the table.
• Verb practice: blank tables to fill in for the tenses you choose, marked box by box, with every tense of every verb on its own review schedule; a verb is learned only when all its tenses are.
• Grammar rules: a rule per page, written as text, table and example blocks, filed under one topic, with highlights and links in the reading view.
• Links: [[Name]] links any item to any other, and every item has a stable page of its own.
• Flashcards: a deck of words and phrases built from chosen lists and filters, or of only what is due, one card at a time, with the typed answer marked and the schedule updated from what happened.
• Tutor: ask a grammar question and get an explanation at your level, built from reference sites for the language you are studying, which you can save as a grammar rule. Conversations are saved and listed beside the chat, searchable by keyword and by meaning, and several answers can be made into one rule.
• Read aloud: a speaker beside every word and phrase, in the lists and on their own pages, and beside a phrase's usage example; one in each verb tense heading that reads the tense down the table; and a floating one on a rule page that reads the whole rule, or only the selected text, each part in the voice of the language it is written in. It uses the browser's own speech, and the speed (Slow, Normal or Fast) is set in Settings.
• Backup: export everything, or one list, as JSON or as an Excel workbook, and import a backup again without disturbing the lists the file says nothing about.
• Accounts: Supabase Auth for sign-in, sign-up and password reset, behind a Cloudflare Turnstile check, with every protected page checked on the server before it renders.

Optional tasks

Two were chosen.

1. Cross-user privacy check. A test confirms that one account's AI context cannot be reached by another. It lives in supabase/tests/multiuser/ (how to rerun it is in the README there) and was first run on 7 October 2026: 626 of 626 checks passed, recorded in Reports/Multi user test.pdf. Three accounts each get a row in every table, including all of the tutor's: conversations, saved answers with their embeddings, rules linked from a conversation, usage and the search log. Each account then attacks the other two, first straight through the database with its own login token and the public key, then through the app in a real browser. For the AI context specifically, it checks that an account cannot:

• read, change or delete another account's conversations, saved answers, linked rules or search log, or add its own rows to them;
• find another account's answers through search_tutor, the search behind both the conversation search and the tutor's memory, which runs under the caller's own session;
• see another account's conversations in the /tutor sidebar, or open one by its address (the page says the conversation was not found);
• ask a question, or merge answers, inside another account's conversation through POST /api/tutor or /api/tutor/merge (refused with 404, and no message spent).

This is the beginning of the README. Read the rest at the original. Read the full README ↗