Files
deepseek-harness/packages/compact/compact/src/invariant.ts
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TypeScript

/** Package-owned compaction log-stream invariants. @module @deepseek-ai/dsh-compact/invariant */
import type { Context } from 'cordis'
import type { Session, SessionEvent } from '@deepseek-ai/dsh-session'
import type { InvariantFailure, InvariantInstaller } from '@deepseek-ai/dsh-invariants'
import type {} from './types.ts'
const PACKAGE_NAME = '@deepseek-ai/dsh-compact'
/** Cordis companion plugin name. */
export const name = 'compact-invariant'
/** Service required before the companion can reserve package ownership. */
export const inject = ['invariants']
interface CompactionTrace {
startSeq: number
turn: number | null
summarized: boolean
}
interface SessionTrace {
openTurn: number | null
compaction: CompactionTrace | undefined
}
type CompactionTransition =
| { kind: 'start'; startSeq: number; turn: number | null }
| { kind: 'summary'; startSeq: number; turn: number | null }
| { kind: 'end' }
| { kind: 'end-seed' }
/** Compaction starts still unmatched when a later seed boundary made them stale. */
function inheritedOrphanStartSeqs(
events: readonly SessionEvent[],
): ReadonlySet<number> {
const stale = new Set<number>()
let openStartSeq: number | undefined
for (const event of events) {
if (event.type === 'compact/start') {
openStartSeq = event.seq
} else if (event.type === 'compact/end') {
openStartSeq = undefined
} else if (event.type === 'session/end-seed') {
if (openStartSeq !== undefined) stale.add(openStartSeq)
openStartSeq = undefined
}
}
return stale
}
/** Keep every live compaction bracket on one side of each turn boundary. */
function validateTurnBoundary(
trace: SessionTrace,
event: SessionEvent,
fail: InvariantFailure,
): void {
if (
(event.type !== 'turn/start' && event.type !== 'turn/end')
|| trace.compaction === undefined
) return
const owner = trace.compaction.turn === null
? 'standalone compaction'
: `compaction for turn ${trace.compaction.turn}`
fail(`${event.type} cannot cross an open ${owner}`)
}
/** Advance the committed turn cursor after its boundary has been accepted. */
function applyTurnBoundary(trace: SessionTrace, event: SessionEvent): boolean {
if (event.type === 'turn/start') {
trace.openTurn = event.data.turn
return true
}
if (event.type === 'turn/end') {
trace.openTurn = null
return true
}
return false
}
/** Require a numbered bracket inside its exact turn, or a standalone bracket between turns. */
function validateOwner(
owner: number | null,
openTurn: number | null,
eventType: 'compact/start' | 'compact/summary' | 'compact/end',
fail: InvariantFailure,
): void {
if (owner === null) {
if (openTurn !== null) fail(`${eventType} is standalone but turn ${openTurn} is open`)
return
}
if (openTurn === null) fail(`${eventType} for turn ${owner} appended outside any open turn`)
if (owner !== openTurn) fail(`${eventType} names turn ${owner} but open turn is ${openTurn}`)
}
/** Validate one compaction event without advancing committed trace state. */
function validateCompactionEvent(
trace: SessionTrace,
event: SessionEvent,
fail: InvariantFailure,
): CompactionTransition | undefined {
if (event.type === 'session/end-seed') return { kind: 'end-seed' }
if (event.type !== 'compact/start' && event.type !== 'compact/summary' && event.type !== 'compact/end') {
return undefined
}
const open = trace.compaction
if (event.type === 'compact/start') {
if (open !== undefined) {
const owner = open.turn === null ? 'standalone compaction' : `turn ${open.turn}`
fail(`compact/start while ${owner} is still compacting`)
}
validateOwner(event.data.turn, trace.openTurn, event.type, fail)
return { kind: 'start', startSeq: event.seq, turn: event.data.turn }
}
if (event.type === 'compact/summary') {
if (open === undefined) fail('compact/summary has no matching compact/start')
validateOwner(open.turn, trace.openTurn, event.type, fail)
if (open.summarized) fail('compact/summary repeated within one compaction')
const seqs = event.data.shadowedSeqs
if (seqs.length === 0) fail('compact/summary shadowedSeqs must be non-empty')
if (seqs[0] !== event.data.shadowedRange.start || seqs.at(-1) !== event.data.shadowedRange.end) {
fail('compact/summary shadowedRange must match the first and last shadowedSeqs')
}
if (!Number.isSafeInteger(event.data.shadowedTokenCount) || event.data.shadowedTokenCount < 0) {
fail('compact/summary shadowedTokenCount must be a non-negative safe integer')
}
return { kind: 'summary', startSeq: open.startSeq, turn: open.turn }
}
if (open === undefined) fail('compact/end has no matching compact/start')
if (event.data.turn !== open.turn) {
fail(`compact/end owner ${String(event.data.turn)} does not match compact/start owner ${String(open.turn)}`)
}
validateOwner(open.turn, trace.openTurn, event.type, fail)
if (event.data.error === undefined && !open.summarized) {
fail('successful compact/end requires one compact/summary')
}
return { kind: 'end' }
}
/** Apply one committed compaction transition. */
function applyCompactionTransition(
transition: CompactionTransition,
): CompactionTrace | undefined {
if (transition.kind === 'start') {
return {
startSeq: transition.startSeq,
turn: transition.turn,
summarized: false,
}
}
if (transition.kind === 'summary') {
return {
startSeq: transition.startSeq,
turn: transition.turn,
summarized: true,
}
}
return undefined
}
/** Install compaction start/summary/end checks. */
// Event owners keep precommit staging local so their vocabularies never move into a central helper.
/* jscpd:ignore-start */
const install: InvariantInstaller = Object.assign((ctx: Context, fail: InvariantFailure) => {
const traces = new WeakMap<Session, SessionTrace>()
const staged = new WeakMap<SessionEvent, { session: Session; transition: CompactionTransition }>()
const seed = (session: Session): SessionTrace => {
const trace: SessionTrace = { openTurn: null, compaction: undefined }
traces.set(session, trace)
const staleOrphanStartSeqs = inheritedOrphanStartSeqs(session.events)
for (const event of session.events) {
// Constructor-seed repair boundaries can precede the end-seed marker
// that proves an inherited orphan stale. Replay that inherited prefix
// without letting the soon-to-be-cleared bracket veto its repair.
if (
trace.compaction === undefined
|| !staleOrphanStartSeqs.has(trace.compaction.startSeq)
) {
validateTurnBoundary(trace, event, fail)
}
const transition = validateCompactionEvent(trace, event, fail)
if (transition !== undefined) trace.compaction = applyCompactionTransition(transition)
applyTurnBoundary(trace, event)
}
return trace
}
const traceFor = (session: Session): SessionTrace => traces.get(session) ?? seed(session)
for (const session of ctx.sessions.list()) seed(session)
ctx.on('session/created', (session) => { seed(session) }, { global: true })
ctx.on('session/event', (session, event) => {
const trace = traceFor(session)
validateTurnBoundary(trace, event, fail)
if (applyTurnBoundary(trace, event)) return
if (event.type !== 'session/end-seed'
&& event.type !== 'compact/start'
&& event.type !== 'compact/summary'
&& event.type !== 'compact/end') return
const candidate = staged.get(event)
/* v8 ignore next -- internal/dispatch stages every compaction event */
if (candidate === undefined || candidate.session !== session) return fail('compaction event published without pre-commit validation')
staged.delete(event)
trace.compaction = applyCompactionTransition(candidate.transition)
}, { global: true })
ctx.on('internal/dispatch', (_mode, eventName, args) => {
if (eventName !== 'session/event') return
const [session, event] = args as [Session, SessionEvent]
const trace = traceFor(session)
validateTurnBoundary(trace, event, fail)
const transition = validateCompactionEvent(trace, event, fail)
if (transition !== undefined) staged.set(event, { session, transition })
}, { global: true })
}, { inject: ['sessions'] })
/* jscpd:ignore-end */
/**
* Register the compact invariant companion.
* @param ctx - Cordis context carrying the invariant service.
* @returns the installed registration's disposer after setup succeeds.
*/
export const apply = (ctx: Context): Promise<() => void> =>
Promise.resolve(ctx.invariants.register(PACKAGE_NAME, install))