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deepseek-harness/packages/session/session-projection-cache/src/spec.ts
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/**
* The projection-cache domain declaration: one `sessions` table keyed by
* {@link SessionId}, each record the full projection checkpoint for one
* session (`key → {ver, seq, val}` rows). The spec object is the single
* source of the domain's identity, version, layout, and record schema; the
* storage-domain routing decides the medium (the shipped composition's json
* backend stores the domain `per-record`: one document per session under
* `<root>/session_projcache/sessions/`, so a checkpoint write rewrites one
* session's document instead of the whole unit).
* @module @deepseek-ai/dsh-session-projection-cache/src/spec
*/
import { z } from 'zod'
import { SessionLogOffset, SessionSeq } from '@deepseek-ai/dsh-session'
import type { SessionId, SessionSeqCursor } from '@deepseek-ai/dsh-session'
import { defineDomain, domainTable } from '@deepseek-ai/dsh-storage-domain'
/**
* One persisted checkpoint row (the RFC's `(sessionId, key, ver, seq, val)`
* minus the two record keys). `val` is the unit's internal state — plain
* JSON by the unit contract; `z.json()` enforces that at the durable
* boundary. A row is never wrong, only possibly stale: `seq` says exactly
* how stale, and a `ver` mismatch against the live unit's `stateVersion`
* discards it at read time (never a migration).
*/
export const checkpointRow = z.object({
ver: z.number().int().nonnegative(),
seq: z.number().int().gte(-1).transform((value): SessionSeqCursor =>
value === -1 ? -1 : SessionSeq(value)),
val: z.json(),
})
/**
* The stored-log identity a record is bound to: the immutable header fields
* that distinguish one session lifecycle from another under the same id. A
* session id names a slot, not a lifecycle — a deleted-then-recreated id, or
* a persistence root swapped under a surviving cache, would otherwise let an
* old record pass every watermark check and seed state folded from an
* unrelated log. Reads validate this against the live header (listing) or
* the stored header (cold read) before accepting any record.
*
* The format and lineage fields are optional because records admitted through
* `compatibleVersions` predate them. The reader (`identityMatches`) refuses an
* absent format generation because no current Session log can prove that
* record's fold semantics. It interprets absent lineage as unseeded only after
* the format generation matches. Current-version writes always store all three
* fields.
*/
export const checkpointIdentity = z.object({
formatVersion: z.number().int().nonnegative().optional(),
createdAt: z.number().int().nonnegative(),
cwd: z.string().optional(),
isSeeded: z.boolean().optional(),
inheritedEventCount: z.number().int().nonnegative().transform(SessionLogOffset).optional(),
})
/** The identity fields a record is bound to, inferred from {@link checkpointIdentity}. */
export type CheckpointIdentity = z.infer<typeof checkpointIdentity>
/**
* One session's stored record: the log identity it was folded from plus its
* checkpoint rows keyed by projection key. The whole record is replaced on
* every write (whole-value discipline — the registry checkpoint is always
* the complete per-session cut).
*/
export const checkpointRecord = z.object({
identity: checkpointIdentity,
rows: z.record(z.string(), checkpointRow),
})
/** One stored per-session checkpoint record, inferred from {@link checkpointRecord}. */
export type CheckpointRecord = z.infer<typeof checkpointRecord>
/**
* The session-projcache domain spec. The `per-record` layout scopes version
* bumps per session: after a bump, a stale session document is discarded on
* open (cache semantics — a stale or unreadable cache costs a longer tail
* replay, never a wrong value) while the rest of the domain stays usable,
* instead of rejecting the whole medium. The `compatibleVersions` entries
* keep structurally valid predecessor records available for a later current
* checkpoint rewrite. Records without `formatVersion` remain unusable as fold
* shortcuts because they cannot prove which Session event semantics produced
* their rows; the per-record version map and disposition live in the read-compat Agent Note
* (.agents/notes/implemented/architecture/2026-09-02-projcache-cross-version-read-compat.md).
* The per-row `ver` guard and the identity match still discard anything the
* current fold semantics cannot vouch for.
*
* A lifecycle-matching predecessor may still expose its version-compatible
* title through the cache service's listing-only hint; this never relaxes the
* format requirement for hydration or another fold shortcut.
*
* `invalidRecords: 'backup-and-skip'`: a stored record that fails the schema
* anyway is disposable derived data, so it must never cost the boot — the
* domain layer moves the document aside as `<key>.json.bak.<stamp>`, logs
* the concrete validation failure, and serves the session as uncached (a
* cold read rebuilds and rewrites it).
*/
export const projectionCacheDomainSpec = defineDomain({
name: 'session_projcache',
version: 7,
compatibleVersions: [3, 4, 5, 6],
invalidRecords: 'backup-and-skip',
layout: 'per-record',
tables: { sessions: domainTable<SessionId, CheckpointRecord>(checkpointRecord) },
})