Glossary

The vocabulary that shows up across every service, and the places two names mean the same thing.

Identity & custody

Term	Meaning
Party	Canton identity, `Hint::Fingerprint`. The fingerprint binds it to a public key.
Vault	Daml contract holding locked collateral for one operator.
Operator	The party that owns the vault, approves withdrawals, submits manifests.
Session key	Ephemeral Ed25519 keypair signing orders. Expires; never touches custody.
Withdrawal counter	Per-party nonce; the replay defence on withdrawal requests.

Trading

Term	Meaning
Market	A perp, e.g. `BTC-USDCX`. The engine symbol, used verbatim everywhere.
`szDecimals`	Size grid exponent. Size must be an exact multiple of `10^-szDecimals`.
`minNotional`	Minimum `price × size` — enforced on the opening leg only.
Reduce-only	An order that can only shrink a position. Exempt from `minNotional`.
Trigger	A TP/SL entry. Lifecycle: `armed` → `cancelled` \| `fired`.
Position epoch	A `positionId` lifetime. A flip ends one and starts another.
Maintenance margin fraction	Equity ratio below which liquidation is eligible.
Funding	Periodic long↔short payment pulling mark toward index.

Off-chain plumbing

Term	Meaning
WAL	The engine's signed write-ahead log. Source of truth for the indexer and the firehose.
Firehose	The engine's admin SSE stream of WAL events, bearer-gated.
Projection	A BFF in-process transform turning WAL events into domain frames.
`seq`	Monotonic WAL sequence number. Pagination and lag measurement both use it.
Mirror	The Postgres copy of engine state written by the indexer (`engine_*` tables).
Leaf	One fill, as a merkle tree entry.
UserBatch	On-chain commitment of one user's leaves for a cadence window.
BatchManifest	On-chain commitment of all `UserBatch` roots for that window.

Same thing, two names

These are the aliases that cause real bugs when someone assumes they are distinct — or assumes they are interchangeable when they are not.

In the engine	In the interface	Note
`BTC` (oracle asset)	`CBTC` (registry key)	Reconciled once, in `resolveTokenKey`.
`USDCX` / `USDC`	`USDCX`	The quote leg arrives spelled both ways.
`BTC-USDCX`	`BTC-USDCX`	One dialect. Never `BTC/USDCx` on the wire.
`market=all`	—	Reserved value on engine admin order reads only.

The old BTC/USDCx WebSocket dialect is gone. The BFF compares markets= exactly, so the mismatched string matched nothing — and an ignored filter silently subscribes you to every market at once. A stream that seems "too chatty" is usually this bug.

Design system

Term	Meaning
Ink ramp	`--t1`…`--t4`. Text hierarchy by alpha, never by hue.
Surface stack	`--bg` → `--surface-3`. Depth by layer, not by shadow.
Pearl button	The 11px default radius, `--r`.
Soft variant	`--green-soft` etc. — the badge background paired with the solid text colour.
Density	`compact` / `comfortable` / `spacious`, via root font-size + a multiplier.

Identity & custody

Trading

Off-chain plumbing

Same thing, two names

Design system

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