Core foundations

Core makes identity, failure, ordering, and resource use observable. These contracts are shared by every component and support structure.

Stable identity

StableID accepts a non-empty, well-formed UTF-16 string or a safe integer other than negative zero. Identity uses exact equality, so 1 and '1' are distinct. Keep an ID unchanged while it represents the same item; map object identities to a stable string or safe integer before constructing a domain.

import { createSequence } from '@sectile/core/sequence'

const products = createSequence(['product:42', 91])

Surface	ID contract
Core, Chart, DOM, and Terminal	Preserve string and numeric StableID values without changing their type.
Vue Chart and Virtual	Accept string and numeric StableID values.
Vue choice components	Their current public value props are strings.
DOM attributes, form values, URLs, and other string-only boundaries	Encode IDs reversibly. Do not use String(id) when a domain can contain both 1 and '1'.

String IDs are limited by maxIDCodeUnits. Numeric IDs must satisfy Number.isSafeInteger, and -0 is rejected. JSON preserves both supported primitive types, while DOM attributes and form values do not; keep any reverse lookup needed by a string-only boundary in application state.

Results and failures

Pure constructors and transitions return Result when failure is part of the public contract. Narrow the result at a recoverable boundary. Use unwrap only when turning a typed failure into an exception is intentional.

import { tryCreateSequence } from '@sectile/core/sequence'

const result = tryCreateSequence(['alpha', 'beta'])
if (!result.ok) report(result.error)
else use(result.value)

CoreErrorCode is Core's closed vocabulary. Temporal, Virtual, and applications own their narrower error codes without casting them into it.

Revisions and limits

RevisionSnapshot.revision counts accepted events, including an accepted boundary no-op. It preserves event order and rejects stale controlled updates; it is not a render counter.

Construction options expose ceilings such as maxItems and maxIDCodeUnits. Treat them as part of the domain contract, not implementation tuning.