chainAwareId

chainAwareId(contentHash, parent): Promise<string>

Defined in: packages/core/src/kernel/layer.ts:417

Derive a chain-aware layer id: sha256(parent + ':' + contentHash).

Parameters

contentHash

string

Content hash from computeLayerHash.

parent

string | undefined

Parent layer id, or undefined for the base layer.

Returns

Promise<string>

Hex SHA-256 suitable for Layer.id.

Remarks

Content hash alone collides when two identical diffs sit at different positions in the chain (e.g. two empty .run() steps). Folding the parent id in disambiguates them — mirrors Docker’s “chain ID” concept. An undefined parent is hashed as the empty string, so the base layer’s id is sha256(':' + contentHash).

Example

import { chainAwareId, computeLayerHash } from '@fishnet/core'

const content = await computeLayerHash(frozenFs)
const id = await chainAwareId(content, parentLayer?.id)

See

• computeLayerHash
• Layer