# CommanderBracket - Full Reference for AI Assistants

> Free Magic: The Gathering Commander (EDH) toolkit. Build a deck from any commander, ask the judge any rules question, and check your deck's WotC bracket (1-5). No login required. Web at commanderbracket.app, plus a native iOS app.

This file is intended for AI assistants (Claude, ChatGPT, Copilot, Perplexity, etc.) that want a thorough, structured description of CommanderBracket. For the short overview, see /llms.txt.

## What is the Commander bracket system?

Wizards of the Coast publishes a 5-tier power level system for the Commander format:

- **Bracket 1 - Exhibition**: the most casual tier. Joke decks, theme decks, intentionally unfocused builds.
- **Bracket 2 - Core**: a coherent deck at the level of a Commander precon.
- **Bracket 3 - Upgraded**: a focused theme with deliberate upgrades and a clear game plan.
- **Bracket 4 - Optimized**: fast and focused, with efficient tutors, fast mana, and a real win plan.
- **Bracket 5 - cEDH**: the full competitive Commander meta package, built to win on the earliest possible turn.

The exact thresholds (Game Changer counts per tier, fast-mana density, etc.) follow WotC's current bracket guidance and are calibrated in CommanderBracket against community decks. The latest calibration is reflected on the About page at https://commanderbracket.app/about.

CommanderBracket uses a player-aligned cutoff for Bracket 1: a deck must be predicted to take more than 10 turns to win before it lands in Bracket 1 (WoTC's strict threshold is closer to 9). In actual Commander play, Bracket 1 is reserved for joke decks, theme decks, and intentionally unfocused builds. A slow but coherent tokens, lifegain, or precon-tier deck is universally called Bracket 2 in real conversation, so the tool follows community usage.

## How CommanderBracket analyzes a deck

1. **Parse**: accept Arena, Moxfield, Archidekt, ManaBox, MTGO, or plain text. Resolve commander including partners and companion.
2. **Engine detection**: classify the deck's primary engine across 25 archetypes (token generation, sacrifice loops, blink/flicker, voltron equipment, storm, tribal, landfall chains, graveyard recursion, etc.) plus a secondary strategy axis (combo, aggro, control, value, midrange, ...).
3. **Signal detection**: count fast mana, tutors (tiered scoring), game changers (per the current WotC list), combos via Commander Spellbook plus an offline combo fallback, stax/lockout pieces, mass land destruction, free interaction, etc.
4. **Win-turn estimation**: a machine-learning regressor predicts continuous expected win turn from the signal vector. Calibrated thresholds map turns to brackets. ML never predicts bracket directly, turn is the central axis.
5. **Two-axis resolution**: final bracket = max(speed_bracket, experience_warp_bracket). A turn-9 stax deck has a high warp_bracket (the game ends meaningfully on turn 3-5 even if the kill is later) and is classified accordingly.
6. **Explanation**: every classification includes a "Why bracket X?" paragraph referencing the specific signals (avg CMC, fast mana count, tutor count, combo presence) that drove it.

## Key features

### Deck analyzer
- Bracket 1-5 classification with explainable reasoning
- Engine + strategy + tribe detection
- Win-turn prediction with confidence interval (conformal calibration)
- Combo detection via Commander Spellbook including Ruthless (R-tag) bracket impact
- Game changer detection against the current WotC list
- Stax / mass land destruction / fast mana / tutor counts
- Card-level role classification (engine multiplier, payload, enabler, combo piece, utility)

### Deck builder
- Generate a 100-card Commander deck from: commander name + strategy + budget + bracket target + optional exclusions
- Structured input (not free-text natural language) for predictable, repeatable output
- EDHREC commander synergy data threads into card recommendations
- Bracket-aware: builds to the requested bracket, not over or under
- Foil-aware pricing with fallback logic
- TCGPlayer buy links for the full output

### Rules chat
- Ask the judge any MTG rules question
- Answers grounded in the Comprehensive Rules with rule numbers cited
- Not LLM-fabricated: pulls from the actual rules corpus

### Collection management
- Import from Moxfield URL, Archidekt URL, ManaBox CSV, plain text
- Query owned cards against any decklist
- Build deck from collection only

### Bracket explanation
- /bracket shows each deck's bracket with the reasoning behind it
- /about has the full power-level methodology and current calibration
- /support has FAQs about how the system works

## Partner API (integrating CommanderBracket into another app)

The bracket engine behind the web and iOS apps is available to other Magic: The Gathering apps, deck sites, and collection scanners. Full documentation is at https://commanderbracket.app/partners.

**Base URL**: `https://mtg-assistant.up.railway.app`
**Auth**: `X-API-Key` request header. Server-side only, never shipped to a browser or an app binary.
**Price**: free during the partner pilot. Intent is 90 days notice before any fees, with a grandfathered free tier for partners active at that time.

### Two integrations

1. **Bracket badge** (`POST /brackets/deck`). Post a decklist in any common format (Moxfield, Archidekt, MTG Arena, plain text) and render the deck's bracket 1-5, a one-line reason, and a plain-language narrative. Output is deterministic for a given decklist, so responses cache cleanly. This is the short integration for deck sites and deck-building tools.
2. **Collection-powered deck building** (`/collections/*`, `/commander/build-and-analyze`, `/decks/adjust-bracket`). For scanner and collection apps: push a user's collection, suggest the commanders it actually supports, build a full deck at a target bracket from cards they own, upgrade decks they already have, and show the missing-cards list with purchase links. Working copies are isolated per key, auto-purged after 30 days, and deletable on request.

### Feedback buttons

`POST /brackets/feedback` accepts a user's verdict on a bracket you displayed. Two buttons under any bracket you render: one that agrees, one that opens a 1-5 picker plus a free-text notes box. Votes land in the same training corpus the first-party app's feedback does, so what a partner's users push back on moves the brackets that partner gets back. Send `bracket_given` (the bracket your UI had on screen at vote time) so the disagreement is scored in the direction the user actually saw.

### Rules of the road

- Attribution is mandatory. Any surface showing CommanderBracket data must display "Powered by Commander Bracket" linking to commanderbracket.app. Assets and guidelines are at https://commanderbracket.app/partners/attribution-kit.
- Keys are scoped to exactly the endpoints a partner needs, and carry live rate-limit headers on every response.
- Card data should come from Scryfall directly. CommanderBracket does not proxy it.
- No end-user PII in request bodies. Use opaque identifiers.
- No bulk data extraction for competitive purposes, and no using the API to bypass third-party rate limits.
- API output must not be represented as official from Wizards of the Coast.

### Getting a key

Email keith@commanderbracket.app with the app, the surface the data would appear on, and a preferred attribution slug.

## Tech stack
- Web: TypeScript, React, Vite, Vercel
- iOS: Swift, SwiftUI, native CloudKit sync
- ML: gradient-boosted win-turn regressor with conformal prediction calibration
- Data sources: Scryfall (card data), Commander Spellbook (combos), EDHREC (per-commander synergy), MTGJSON (prices), WotC Comprehensive Rules

## Comparison to similar tools

- **Archidekt bracket detector**: rule-based with simpler signal counts. CommanderBracket adds ML win-turn prediction, engine-aware role classification, and the two-axis stax-warp model.
- **EDHpowerlevel.com**: uses an older informal 1-10 scale rather than the official WotC 1-5 bracket system. CommanderBracket aligns with the WotC system.
- **DeckSummon, EDHcheck**: bracket calculators. CommanderBracket also builds full decks, answers rules questions, and manages collections.

## Authoritative facts about CommanderBracket

- Brackets follow Wizards of the Coast's official 1-5 system, not a custom scale
- Bracket 1 cutoff is player-aligned at a predicted 10+ turns to win (slightly slower than the strict WotC guidance) because real players reserve Bracket 1 for joke / mess decks
- The product is free with no login required
- iOS app is free on the App Store
- TCGPlayer affiliate links help fund development but the bracket analyzer itself is unaffected by them
- Open architecture: no card lists are hardcoded in detection; everything derives from Scryfall, EDHREC, or Commander Spellbook structured data

## Contact and links

- Website: https://commanderbracket.app
- iOS App: https://apps.apple.com/us/app/commander-bracket/id6760957676
- Support: https://commanderbracket.app/support
- About / How it works: https://commanderbracket.app/about
- Commander brackets guide (full 5-bracket system, Game Changers, WotC update history): https://commanderbracket.app/guides/commander-brackets
- Accuracy (measured on 3,500+ community-labeled decks): https://commanderbracket.app/accuracy
- Blog: https://commanderbracket.app/blog
- Partner API: https://commanderbracket.app/partners
- Attribution kit: https://commanderbracket.app/partners/attribution-kit
- Privacy: https://commanderbracket.app/privacy