Import
import { MemoryOptions } from "@typed/navigation/memory";Signatures
export interface MemoryOptions {
readonly entries: ReadonlyArray<Destination>;
readonly origin?: string | undefined;
readonly base?: string | undefined;
readonly currentIndex?: number | undefined;
readonly maxEntries?: number | undefined;
readonly commit?: (before: BeforeNavigationEvent, runHandlers: (destination: Destination) => Effect.Effect<void>) => Effect.Effect<Destination, NavigationError>;
}Why
SSR, tests, and non-browser runtimes need deterministic history without emulating window.
maxEntries bounds retained history; pushing after traversal truncates forward entries. entries
must be non-empty, maxEntries must be greater than zero, and currentIndex must address an entry
that survives the initial tail-retention transform. When entries.length > maxEntries, that means
currentIndex >= entries.length - maxEntries. The provider currently trusts these invariants:
violating them can produce a negative transformed index and an undefined currentEntry. Despite
its name, maxEntries: 0 currently retains every entry because slice(-0) is slice(0). Prefer
{@link initialMemory} when starting from a URL rather than a prebuilt history snapshot.
Ownership and lifetime
The Layer retains the supplied entries array as its initial snapshot; it does not clone it.
Callers must treat that array and its destinations as immutable. Later transitions install new
arrays in the provider RefSubject. A custom commit function is retained for the service lifetime.
Property: base
The structural base path exposed by the active provider.
Property: base: Why
Routers can establish a stable mount root separately from the changing current URL.
Property: base: Ownership and lifetime
The string is read when the Layer is acquired and retained on the Navigation service.
Property: commit
The backend hook that commits a prepared memory transition.
Property: commit: Why
Advanced providers can preserve the shared state machine while controlling persistence and handler timing.
Property: commit: Ownership and lifetime
The provider retains the function for its service lifetime and invokes its returned Effect once per commit. Resources acquired by that Effect follow the active navigation fiber and its Scope.
Property: currentIndex
The zero-based active position before initial tail retention.
Property: currentIndex: Why
SSR snapshots and tests can restore traversal position instead of assuming the last entry, but the selected entry must remain inside the retained tail.
Property: currentIndex: Ownership and lifetime
The index is read during Layer acquisition. It must address entries and, when
entries.length > maxEntries, satisfy currentIndex >= entries.length - maxEntries. The
retention transform subtracts the evicted prefix length; violating this precondition produces a
negative index and leaves currentEntry undefined. No runtime validation is currently performed.
Property: entries
The initial committed history snapshot in traversal order.
Property: entries: Why
Back, forward, and keyed traversal need an explicit history model before retention is applied.
Property: entries: Ownership and lifetime
The Layer retains this array by reference as the first history snapshot. Do not mutate it after Layer acquisition; later provider updates replace the array rather than taking ownership of caller mutation.
Property: maxEntries
The positive maximum number of history entries retained by the provider.
Property: maxEntries: Why
A positive bound makes eviction deterministic: the provider keeps the newest tail and adjusts the active index by the number of evicted entries.
Property: maxEntries: Ownership and lifetime
The number is captured by the RefSubject transformation for the Navigation service lifetime and
must be greater than zero. No validation enforces that contract. 0 currently retains all
entries because JavaScript evaluates slice(-0) as slice(0); it is not a zero-capacity mode.
Property: origin
The absolute origin used to resolve relative destinations.
Property: origin: Why
A single origin makes same-document classification and URL normalization consistent across providers.
Property: origin: Ownership and lifetime
The string is read when the Layer is acquired and retained on the Navigation service.
Other public imports
These import paths expose the same declaration. Each page retains its own public name and signature.