feat(compact-basic): baseline compaction backend (squashed from compact-basic)
Collapses the per-round review churn of the prior compact-basic branch into a single clean baseline on top of compact-interface, so the upcoming retention refactor lands as fresh, well-scoped commits rather than stacking on a history of fixes that are being superseded.
This commit is contained in:
Hypatia May
@@ -19,6 +19,7 @@ export { isJsonValue } from './json.ts'
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export { interruptedTurnClosers } from './repair.ts'
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export type { SurfaceNode } from './surface.ts'
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export { isSurfaceEvent, isSurfaceEligibleType } from './surface.ts'
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export { isStepAlignedStart, isStepAlignedEnd } from './step-boundary.ts'
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declare module 'cordis' {
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interface Context {
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97
packages/core/session/src/step-boundary.ts
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97
packages/core/session/src/step-boundary.ts
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@@ -0,0 +1,97 @@
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/**
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* Step-boundary predicates over a session log: is a given surface node a SAFE
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* place to start or end a region that will be collapsed (e.g. by compaction)?
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*
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* The invariant a consumer needs: a collapsed region must NOT partially overlap
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* a step. A step's surface nodes form a contiguous run, and a region must
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* contain either ALL of a step's nodes or NONE of them — otherwise it can split
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* an `assistant/message`'s `tool-call` blocks from their `tool/result`s, leaving
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* the rehydrated transcript with a dangling tool-call or an orphaned tool-result
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* (which every provider rejects). This is the compaction-time mirror of the
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* crash-recovery imbalance that {@link interruptedTurnClosers} repairs on load.
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*
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* Nodes that belong to NO step — a pre-step `user/message` (drained before the
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* first `step/start`), inter-step `steering/message`, or an injection
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* `context/message` (wrapped in a bare `turn/start → context/message → turn/end`
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* with no step) — carry no tool pairing and are free boundaries on both sides.
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*
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* The scans classify each neighbor event into three buckets: a turn/step
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* BOUNDARY marker (the region edge is clean), a SURFACE node (the region edge
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* is mid-step), or NOISE to skip (`assistant/chunk`, the log-only `compact/*`
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* records, and any future non-surface event). "Surface node" is decided by the
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* shared {@link isSurfaceEvent} guard so the two notions can't drift.
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*
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* @module @deepseek-ai/dsh-session/step-boundary
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*/
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import type { SessionEvent } from './types.ts'
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import { isSurfaceEvent } from './surface.ts'
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/** Turn/step boundary marker types — the walls the scans stop on. */
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const BOUNDARY_TYPES = new Set<string>(['turn/start', 'turn/end', 'step/start', 'step/end'])
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/**
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* Whether the surface node at `seq` is a SAFE START for a collapsed region —
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* i.e. it is the first surface node of its step, or it belongs to no step at
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* all (a free inter-step / pre-step / injection node).
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*
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* Scans BACKWARD from `seq`, skipping noise, and stops at the first significant
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* event: a turn/step boundary marker ⇒ aligned (nothing of `seq`'s step lies
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* before it), a surface node ⇒ NOT aligned (a predecessor surface node sits in
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* the same step, so starting here would orphan it), start-of-log ⇒ aligned.
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*
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* No open-step check is needed on the start side: an open (unclosed) step can
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* only ever be the LAST turn's last step, never before a valid region start.
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*/
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export function isStepAlignedStart(events: readonly SessionEvent[], seq: number): boolean {
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for (let i = seq - 1; i >= 0; i--) {
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// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
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const event = events[i]!
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if (BOUNDARY_TYPES.has(event.type)) return true
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if (isSurfaceEvent(event)) return false
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}
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return true
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}
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/**
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* Whether the surface node at `seq` is a SAFE END for a collapsed region —
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* i.e. it is the last surface node of a CLOSED step, or it belongs to no step
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* at all.
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*
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* Scans FORWARD from `seq`, skipping noise, and stops at the first significant
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* event: a turn/step boundary marker ⇒ aligned (the step/turn closes after
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* `seq`, or a new one begins because `seq` was inter-step), a surface node ⇒
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* NOT aligned (a later surface node sits in the same step). Reaching
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* end-of-log is aligned ONLY when `seq` is not inside an OPEN step — an open
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* trailing step's `tool-call`s have no `tool/result`s yet, so collapsing it
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* would defer the orphan to when those results land later. {@link isInOpenStep}
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* decides that via a backward scan.
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*/
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export function isStepAlignedEnd(events: readonly SessionEvent[], seq: number): boolean {
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for (let i = seq + 1; i < events.length; i++) {
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// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
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const event = events[i]!
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if (BOUNDARY_TYPES.has(event.type)) return true
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if (isSurfaceEvent(event)) return false
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}
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// End of log: aligned only if `seq` is not inside a still-open step.
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return !isInOpenStep(events, seq)
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}
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/**
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* Whether `seq` sits inside an OPEN step — a `step/start` with no later
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* `step/end`. Only meaningful at the tail (the EOL branch of
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* {@link isStepAlignedEnd}): scans BACKWARD for the nearest turn/step boundary.
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* The nearest one being `step/start` means a step opened before `seq` and never
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* closed (no `step/end` lies after `seq`, or the forward scan would not have
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* reached EOL) — so `seq` is mid-open-step. Any other nearest boundary (or none)
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* means `seq` is inter-step / pre-step.
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*/
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function isInOpenStep(events: readonly SessionEvent[], seq: number): boolean {
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for (let i = seq - 1; i >= 0; i--) {
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// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
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const type = events[i]!.type
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if (BOUNDARY_TYPES.has(type)) return type === 'step/start'
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}
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return false
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}
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172
packages/core/session/tests/step-boundary.spec.ts
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172
packages/core/session/tests/step-boundary.spec.ts
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@@ -0,0 +1,172 @@
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import { describe, expect, it } from 'vitest'
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import { CallId } from '@deepseek-ai/dsh-llm'
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import { isStepAlignedStart, isStepAlignedEnd } from '../src/index.ts'
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import type { SessionEvent } from '../src/index.ts'
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/**
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* Unit coverage for the step-alignment predicates. They decide whether a
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* surface node is a safe START / END for a collapsed region (compaction): a
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* region must contain whole steps, never split an `assistant/message`'s
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* tool-calls from their `tool/result`s. Nodes belonging to no step (pre-step
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* user message, inter-step steering, injection context) are free boundaries.
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*
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* Builders mirror the agent loop's real append order so the fixtures are
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* representative: queued user messages land BEFORE `step/start`; within a step
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* the order is `assistant/message` then `tool/result`(s); injection turns are a
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* bare `turn/start → context/message → turn/end` with no step.
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*/
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const SURFACE = { surfaceOp: 'append' as const }
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/** A closed turn with one closed step holding an assistant + its tool result. */
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function toolStepLog(): SessionEvent[] {
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return [
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{ type: 'turn/start', seq: 0, time: 0, data: { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } } },
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{ type: 'user/message', seq: 1, time: 1, data: { content: [{ type: 'text', text: 'go' }], source: { kind: 'user' } }, ...SURFACE },
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{ type: 'step/start', seq: 2, time: 2, data: { turn: 1, step: 1 } },
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{ type: 'assistant/message', seq: 3, time: 3, data: { turn: 1, step: 1, content: [
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{ type: 'text', text: 'calling' },
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{ type: 'tool-call', id: CallId('c1'), name: 'bash', arguments: '{}' },
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] }, ...SURFACE },
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{ type: 'tool/call', seq: 4, time: 4, data: { turn: 1, step: 1, callId: CallId('c1'), name: 'bash', arguments: '{}' } },
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{ type: 'tool/result', seq: 5, time: 5, data: { turn: 1, step: 1, callId: CallId('c1'), content: [{ type: 'text', text: 'out' }], isError: false }, ...SURFACE },
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{ type: 'step/end', seq: 6, time: 6, data: { turn: 1, step: 1 } },
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{ type: 'turn/end', seq: 7, time: 7, data: { turn: 1, reason: { kind: 'completed' } } },
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]
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}
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describe('isStepAlignedStart', () => {
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it('is true for a pre-step user/message (belongs to no step)', () => {
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// seq 1 user/message sits before step/start at seq 2 → free boundary.
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expect(isStepAlignedStart(toolStepLog(), 1)).toBe(true)
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})
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it('is true for the first surface node of a step (the assistant/message)', () => {
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// Backward from seq 3 the first significant event is step/start → aligned.
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expect(isStepAlignedStart(toolStepLog(), 3)).toBe(true)
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})
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it('is false for a tool/result whose assistant/message precedes it in the same step', () => {
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// Backward from seq 5 the first significant event is the assistant/message
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// surface node (seq 3) → starting here would orphan that assistant's call.
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expect(isStepAlignedStart(toolStepLog(), 5)).toBe(false)
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})
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it('is true at start-of-log (nothing precedes)', () => {
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const log: SessionEvent[] = [
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{ type: 'user/message', seq: 0, time: 0, data: { content: [{ type: 'text', text: 'hi' }], source: { kind: 'user' } }, ...SURFACE },
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]
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expect(isStepAlignedStart(log, 0)).toBe(true)
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})
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it('skips noise (assistant/chunk, compact/* records) when scanning back', () => {
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// A compacted region landed compact/* log-only records between the prior
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// step boundary and this surface node; they must be skipped, not treated as
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// walls. Backward from seq 4 skips compact/end, compact/summary, compact/start
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// and stops at step/start (seq 0) → aligned.
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const log: SessionEvent[] = [
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{ type: 'step/start', seq: 0, time: 0, data: { turn: 1, step: 1 } },
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{ type: 'compact/start', seq: 1, time: 1, data: { turn: 1 } } as unknown as SessionEvent,
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{ type: 'compact/summary', seq: 2, time: 2, data: { summary: [], shadowedRange: { start: 0, end: 0 }, shadowedSeqs: [], shadowedTokenCount: 0 } } as unknown as SessionEvent,
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{ type: 'compact/end', seq: 3, time: 3, data: { turn: 1 } } as unknown as SessionEvent,
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{ type: 'assistant/message', seq: 4, time: 4, data: { turn: 1, step: 1, content: [{ type: 'text', text: 'a' }] }, ...SURFACE },
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]
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expect(isStepAlignedStart(log, 4)).toBe(true)
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})
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})
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describe('isStepAlignedEnd', () => {
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it('is true for the last surface node of a closed step (the tool/result)', () => {
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// Forward from seq 5 the first significant event is step/end → aligned.
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expect(isStepAlignedEnd(toolStepLog(), 5)).toBe(true)
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})
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it('is false for an assistant/message with a later tool/result in the same step', () => {
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// Forward from seq 3 the first significant event is the tool/result surface
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// node (seq 5) → ending here would strand that result.
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expect(isStepAlignedEnd(toolStepLog(), 3)).toBe(false)
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})
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it('is true for a pre-step user/message (next significant event is step/start)', () => {
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expect(isStepAlignedEnd(toolStepLog(), 1)).toBe(true)
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})
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it('is false at EOL when the node is inside an open (unclosed) step', () => {
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// step/start then an assistant tool-call, but no step/end / tool/result yet
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// (mid-flight). Ending the region on seq 3 would summarize away a tool-call
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// whose result lands later → orphan. EOL + open step ⇒ not aligned.
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const log: SessionEvent[] = [
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{ type: 'turn/start', seq: 0, time: 0, data: { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } } },
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{ type: 'step/start', seq: 1, time: 1, data: { turn: 1, step: 1 } },
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{ type: 'assistant/message', seq: 2, time: 2, data: { turn: 1, step: 1, content: [
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{ type: 'tool-call', id: CallId('c1'), name: 'bash', arguments: '{}' },
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] }, ...SURFACE },
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]
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expect(isStepAlignedEnd(log, 2)).toBe(false)
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})
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it('is false at EOL when the node is inside an open step, skipping noise on the back-scan', () => {
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// The open-step back-scan must skip non-boundary events (here an
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// assistant/chunk) before it reaches step/start. Without the skip it would
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// mis-read the chunk as the nearest "boundary" and never confirm the open step.
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const log: SessionEvent[] = [
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{ type: 'turn/start', seq: 0, time: 0, data: { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } } },
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{ type: 'step/start', seq: 1, time: 1, data: { turn: 1, step: 1 } },
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{ type: 'assistant/chunk', seq: 2, time: 2, data: { turn: 1, step: 1, chunk: { type: 'text-delta', index: 0, text: 'h' } } },
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{ type: 'assistant/message', seq: 3, time: 3, data: { turn: 1, step: 1, content: [
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{ type: 'tool-call', id: CallId('c1'), name: 'bash', arguments: '{}' },
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] }, ...SURFACE },
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]
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expect(isStepAlignedEnd(log, 3)).toBe(false)
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})
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it('is true at EOL when the node is a trailing inter-step node (step already closed)', () => {
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// A steering message appended after step/end, at the tail. Backward the
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// nearest boundary is step/end → not in an open step → aligned.
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const log: SessionEvent[] = [
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{ type: 'step/start', seq: 0, time: 0, data: { turn: 1, step: 1 } },
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{ type: 'assistant/message', seq: 1, time: 1, data: { turn: 1, step: 1, content: [{ type: 'text', text: 'a' }] }, ...SURFACE },
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{ type: 'step/end', seq: 2, time: 2, data: { turn: 1, step: 1 } },
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{ type: 'steering/message', seq: 3, time: 3, data: { turn: 1, content: [{ type: 'text', text: 's' }], source: { kind: 'user' } }, ...SURFACE },
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]
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expect(isStepAlignedEnd(log, 3)).toBe(true)
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})
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it('is true at EOL when no step ever opened (start-of-log fallback in open-step check)', () => {
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// A lone surface node, no turn/step markers at all → not in an open step.
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const log: SessionEvent[] = [
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{ type: 'user/message', seq: 0, time: 0, data: { content: [{ type: 'text', text: 'hi' }], source: { kind: 'user' } }, ...SURFACE },
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]
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expect(isStepAlignedEnd(log, 0)).toBe(true)
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})
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it('skips noise (assistant/chunk) when scanning forward', () => {
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// assistant/chunk events precede the assistant/message in a real step; the
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// forward scan from an inter-step node must skip them and stop on step/start.
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const log: SessionEvent[] = [
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{ type: 'user/message', seq: 0, time: 0, data: { content: [{ type: 'text', text: 'go' }], source: { kind: 'user' } }, ...SURFACE },
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{ type: 'step/start', seq: 1, time: 1, data: { turn: 1, step: 1 } },
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{ type: 'assistant/chunk', seq: 2, time: 2, data: { turn: 1, step: 1, chunk: { type: 'text-delta', index: 0, text: 'h' } } },
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]
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// Forward from seq 0 hits step/start at seq 1 → aligned (noise after is moot).
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expect(isStepAlignedEnd(log, 0)).toBe(true)
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})
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})
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describe('step-alignment on an injection turn (no step)', () => {
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// An idle inject() wraps a context/message in a bare turn/start → context/message
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// → turn/end with NO step/start. The context node is a free boundary both ways.
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const injectionLog = (): SessionEvent[] => [
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{ type: 'turn/start', seq: 0, time: 0, data: { turn: 1, trigger: { kind: 'injection', source: { kind: 'user' } } } },
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{ type: 'context/message', seq: 1, time: 1, data: { content: [{ type: 'text', text: 'ctx' }], source: { kind: 'user' } }, ...SURFACE },
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{ type: 'turn/end', seq: 2, time: 2, data: { turn: 1, reason: { kind: 'completed' } } },
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]
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it('start: aligned (backward hits turn/start)', () => {
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expect(isStepAlignedStart(injectionLog(), 1)).toBe(true)
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})
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it('end: aligned (forward hits turn/end)', () => {
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expect(isStepAlignedEnd(injectionLog(), 1)).toBe(true)
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})
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})
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Reference in New Issue
Block a user