Owned Cards

Upload your card collection and build decks using only — or preferring — cards you already own.

Overview

The Owned Cards feature lets you upload lists of cards you own. Once uploaded, these lists integrate into the build pipeline so the builder can filter or bias card selection toward your collection.

Uploading Your Library

Go to /owned in the web UI to manage your owned card library.

Supported Formats

Format	Notes
`.txt`	One card name per line. Optionally prefix with a count: `4x Sol Ring` or `4 Sol Ring`.
`.csv`	Must include at minimum a `name` column. A `count` column is optional.

Cards are enriched and deduplicated automatically on upload. Near-duplicate names (e.g., different printings) are resolved against the card catalog.

Multiple Files

You can upload multiple files. All are merged into a single owned library for the session. To replace the library, delete existing files and re-upload.

Build Modes

Select the owned card mode in the New Deck modal:

Mode	Behavior
No filter (default)	Owned cards have no special weight; all on-theme cards are eligible.
Prefer owned	Cards you own are weighted higher in the selection pool. Non-owned cards are still eligible if the pool would otherwise be too thin.
Owned only	Only cards in your owned library are eligible for selection. Builds may be thinner if your library doesn't cover a theme well.

Alternatives Panel (Replace)

When using Replace in Step 5, toggle Owned only in the Alternatives panel to restrict replacement candidates to cards in your library.

Performance

For large libraries (1,000+ cards), enable list virtualization to improve scroll performance in the Owned Library page:

WEB_VIRTUALIZE=1

Environment Variables

Variable	Default	Purpose
`OWNED_CARDS_DIR` / `CARD_LIBRARY_DIR`	`/app/owned_cards`	Override the directory where owned card files are stored. Mount this volume to persist across container restarts.
`WEB_VIRTUALIZE`	`1`	Enable virtualized lists for large owned libraries and Step 5 card grids.

Headless / CLI

In headless mode, set the owned card mode via JSON config:

{
  "owned_only": true,
  "prefer_owned": false
}

Use "prefer_owned": true for soft weighting, "owned_only": true for hard filtering. The two are mutually exclusive; owned_only takes precedence if both are set.

FAQ

My owned card file uploaded but no cards are being filtered — what's wrong?
Check that the file is in a supported format (plain text, one card per line, or a standard CSV export). Card names must match the Scryfall canonical name exactly (e.g., "Sol Ring" not "sol ring"). Check the diagnostics page for parse errors.

Can I use multiple owned card files?
Yes. All files in the owned_cards/ directory are merged automatically. If the same card appears in multiple files, it is counted once.

Does prefer_owned guarantee my owned cards appear in the deck?
No — prefer_owned adds a weight boost during pool selection, but owned cards compete with the rest of the pool. If you need a specific card guaranteed, add it to Must Include instead.

What happens if I'm in owned_only mode and there aren't enough owned cards in a category?
The builder fills the category with the cards available and may produce a deck with fewer cards than the ideal count for that slot. The build summary will note any under-filled categories.

MTG Deckbuilder