@sema-agent/core/dist/stores/file/checkpoint-store.js

Stateless, task-oriented AI agent core

import { join } from "node:path";
import { assertAdoptionBootGate } from "./adoption/marker.js";
import { checkpointExecutionRecorded, executionRecordDisposition, ExecutionOutcomeConflictError, } from "../../core/checkpoint-execution-record.js";
import { appendPendingSteer, CheckpointError, checkpointOccMatches, checkpointRowMatches, encodeAtFidelity, summarizeCheckpoint, validatePendingSteer, winnerFromOutcome, } from "../../core/checkpoint-store.js";
import { SharedLedgerTable } from "./shared-ledger.js";
import { guardCorruptSink } from "./corrupt-read-sink.js";
const CHECKPOINT_LEDGER_EVENT_REGISTRY = {
    put: true,
    resolve: true,
    reopen: true,
    execution: true,
    expire: true,
    steer_append: true,
};
const KNOWN_CHECKPOINT_LEDGER_EVENTS = new Set(Object.keys(CHECKPOINT_LEDGER_EVENT_REGISTRY));
function applyCheckpointEvent(cps, ev) {
    if (!KNOWN_CHECKPOINT_LEDGER_EVENTS.has(ev.t)) {
        throw new CheckpointError("checkpoint.unsupported_version", `file checkpoint ledger: unrecognised event kind "${String(ev.t)}" — ` +
            `it was written by a newer worker, or it is a kind this engine retired; refusing the replay rather than serving an incomplete authority`, { reason: "ledger_event_unknown" });
    }
    if (ev.t === "put") {
        cps.set(ev.token, ev.cp);
        return;
    }
    const cp = cps.get(ev.token);
    if (!cp)
        return;
    switch (ev.t) {
        case "resolve":
            cp.status = "resolved";
            cp.rev = ev.rev;
            if (ev.resolvedOutcome !== undefined)
                cp.resolvedOutcome = ev.resolvedOutcome;
            cp.reopenReason = undefined;
            break;
        case "reopen":
            cp.status = "pending";
            cp.rev = ev.rev;
            cp.reopenReason = ev.reason;
            break;
        case "execution":
            cp.executionOutcome = ev.gate;
            cp.executionAtMs = ev.atMs;
            break;
        case "expire":
            cp.status = "expired";
            break;
        case "steer_append": {
            const queue = cp.state.pendingSteerQueue ?? [];
            if (!queue.some((e) => e.inputId === ev.entry.inputId))
                cp.state.pendingSteerQueue = [...queue, ev.entry];
            break;
        }
        default: {
            const _exhaustive = ev;
            void _exhaustive;
            break;
        }
    }
}
const isCheckpointRow = (x) => x !== null &&
    typeof x === "object" &&
    typeof x.token === "string" &&
    typeof x.scope === "string" &&
    typeof x.status === "string";
const checkpointLedgers = new SharedLedgerTable({
    label: "checkpoint ledger",
    keyOf: (cp) => cp.token,
    apply: applyCheckpointEvent,
    judgeRow: isCheckpointRow,
    judgeEvent: (x) => {
        const ev = x;
        if (typeof ev.t !== "string")
            return false;
        if (!KNOWN_CHECKPOINT_LEDGER_EVENTS.has(ev.t))
            return true;
        if (typeof ev.token !== "string")
            return false;
        return ev.t === "put" ? isCheckpointRow(ev.cp) : true;
    },
});
export class FileCheckpointStore {
    durability = "durable";
    fidelity = "json";
    redecision = { reopen: true };
    execution = { outcome: true };
    fsyncEnabled;
    compactEvery;
    ledger;
    closed = false;
    get cps() {
        return this.ledger.rows;
    }
    fault = null;
    constructor(root, opts = {}) {
        assertAdoptionBootGate(root, "FileCheckpointStore");
        this.fsyncEnabled = opts.fsync !== false;
        this.compactEvery = opts.compactEvery ?? 1000;
        const dir = join(root, "checkpoints");
        this.ledger = checkpointLedgers.acquire({
            dir,
            tmpDir: join(root, "tmp"),
            ...(opts.onCorruptRead !== undefined ? { onCorruptRead: guardCorruptSink(opts.onCorruptRead) } : {}),
            ledgerPath: join(dir, "checkpoints.jsonl"),
            snapshotPath: join(dir, "checkpoints.snapshot.jsonl"),
        });
    }
    withLock(token, fn) {
        return this.ledger.withLock(token, fn);
    }
    commit(ev, fsync) {
        const held = encodeAtFidelity(this.fidelity, ev);
        if (!held.ok)
            throw held.cause;
        this.ledger.commit(held.value, fsync, this.compactEvery);
    }
    async put(token, cp) {
        return this.withLock(token, () => {
            if (this.cps.has(token)) {
                throw new CheckpointError("checkpoint.already_exists", `checkpoint token already exists`);
            }
            const stored = structuredClone(cp);
            this.commit({ t: "put", token, cp: stored }, this.fsyncEnabled);
        });
    }
    async get(token) {
        const cp = this.cps.get(token);
        return cp ? structuredClone(cp) : null;
    }
    async resolve(token, scope, outcome, expect) {
        return this.withLock(token, () => {
            if (this.fault === "resolve-before-commit") {
                this.fault = null;
                throw new Error("injected fault: resolve before commit");
            }
            const cp = this.cps.get(token);
            if (!checkpointRowMatches(cp, scope, "pending")) {
                return false;
            }
            if (!checkpointOccMatches(cp, expect)) {
                return false;
            }
            const winner = winnerFromOutcome(outcome);
            const rev = (cp.rev ?? 0) + 1;
            this.commit({ t: "resolve", token, rev, resolvedOutcome: winner }, true);
            if (this.fault === "resolve-after-commit") {
                this.fault = null;
                throw new Error("injected fault: resolve after commit");
            }
            return true;
        });
    }
    async recordExecutionOutcome(token, scope, gate) {
        return this.withLock(token, () => {
            const cp = this.cps.get(token);
            const disposition = executionRecordDisposition(cp, scope, gate);
            if (disposition === "conflict")
                throw new ExecutionOutcomeConflictError(cp.executionOutcome, gate);
            if (disposition !== "commit")
                return disposition;
            this.commit({ t: "execution", token, gate: structuredClone(gate), atMs: Date.now() }, true);
            return "recorded";
        });
    }
    async reopen(token, scope, reason) {
        return this.withLock(token, () => {
            const cp = this.cps.get(token);
            if (!checkpointRowMatches(cp, scope, "resolved") || checkpointExecutionRecorded(cp)) {
                return false;
            }
            const rev = (cp.rev ?? 0) + 1;
            this.commit({ t: "reopen", token, rev, reason }, true);
            return true;
        });
    }
    async setPendingSteer(token, scope, steer) {
        const clean = validatePendingSteer(steer);
        return this.withLock(token, () => {
            const cp = this.cps.get(token);
            if (!checkpointRowMatches(cp, scope, "pending")) {
                return false;
            }
            const next = appendPendingSteer(cp.state, clean);
            const appended = next[next.length - 1];
            if (appended === undefined || appended.inputId !== clean.inputId)
                return true;
            this.commit({ t: "steer_append", token, entry: appended }, this.fsyncEnabled);
            return true;
        });
    }
    async expire(token, scope) {
        return this.withLock(token, () => {
            const cp = this.cps.get(token);
            if (!checkpointRowMatches(cp, scope, "pending")) {
                return false;
            }
            this.commit({ t: "expire", token }, true);
            return true;
        });
    }
    async reap(scope, cutoff) {
        let n = 0;
        const deadlinePassed = (deadline) => deadline !== undefined && (Number.isFinite(deadline) ? deadline <= cutoff : true);
        const candidates = [...this.cps.values()].filter((cp) => cp.scope === scope && cp.status === "pending" && deadlinePassed(cp.deadline));
        for (const cp of candidates) {
            const won = await this.withLock(cp.token, () => {
                const live = this.cps.get(cp.token);
                if (!live || live.scope !== scope || live.status !== "pending")
                    return false;
                if (!deadlinePassed(live.deadline))
                    return false;
                this.commit({ t: "expire", token: cp.token }, true);
                return true;
            });
            if (won)
                n++;
        }
        return n;
    }
    async listByScope(scope) {
        const out = [];
        for (const cp of this.cps.values()) {
            if (cp.scope === scope && cp.status === "pending")
                out.push(summarizeCheckpoint(cp));
        }
        return out;
    }
    async listScopes() {
        const out = new Set();
        for (const cp of this.cps.values())
            if (cp.status === "pending")
                out.add(cp.scope);
        return [...out];
    }
    compactNow() {
        this.ledger.compact();
    }
    testInjectFault(mode) {
        this.fault = mode;
    }
    get size() {
        return this.cps.size;
    }
    close() {
        if (this.closed)
            return;
        this.closed = true;
        this.ledger.release();
    }
}