OpenWOP — RFC 0015: host.kvStorage capability

RFC details authors, dates, what it affects, review history

Field	Value
RFC	0015
Title	host.kvStorage key-value capability
Status	`Accepted`
Author(s)	OpenWOP Working Group
Created	2026-05-17
Updated	2026-05-18 (Active → Accepted: all 5 acceptance-criteria items satisfied. `capabilities.kvStorage` block in schema; `spec/v1/host-capabilities.md §host.kvStorage` landed at commit c5831fe; invariant `kv-cross-tenant-isolation` + 4 scenarios (`kv-cross-tenant-isolation`, `kv-atomic-increment`, `kv-cas`, `kv-ttl-expiry`) all behavioral; reference impl advertised in `routes/discovery.ts` lines 176–184; CHANGELOG entry under `[Unreleased]`.)
Affects	`spec/v1/host-capabilities.md` · `schemas/capabilities.schema.json` · `SECURITY/invariants.yaml` (cross-tenant) · new conformance scenarios
Compatibility	`additive`

Summary

Adds an optional host.kvStorage capability — a TTL-aware key-value store with atomic increment + compare-and-swap primitives. Required by core.openwop.storage's kv-\* nodes. The Make-Data-Store equivalent for openwop.

Motivation

Workflows need cross-run state. Today every pack invents its own external store (Redis client, Postgres table, S3 prefix), each with a different cross-tenant isolation bug. A single capability with a single SECURITY invariant for cross-tenant isolation is the leverage point.

Proposal

§A Capability schema addition

{
  "kvStorage": {
    "type": "object",
    "description": "Key-value store with TTL + atomic ops. Per-tenant isolation enforced by the host.",
    "properties": {
      "supported": { "type": "boolean" },
      "maxKeyBytes": { "type": "integer", "minimum": 0 },
      "maxValueBytes": { "type": "integer", "minimum": 0 },
      "maxTtlSeconds": { "type": "integer", "minimum": 0 },
      "atomicIncrement": { "type": "boolean" },
      "compareAndSwap": { "type": "boolean" }
    },
    "additionalProperties": false
  }
}

§B Host-contract MUSTs

A host advertising kvStorage.supported: true MUST:

Partition values by tenant. A get for one tenant MUST NOT return values from another tenant, even with identical keys.
Enforce maxKeyBytes and maxValueBytes advertised values.
Honor TTL with at most a 1-second drift on expiry visibility.
If atomicIncrement: true is advertised, increments MUST be atomic across concurrent callers.
If compareAndSwap: true is advertised, CAS MUST be atomic (no read-modify-write races).

§C SECURITY invariant

- id: kv-cross-tenant-isolation
  tier: protocol
  summary: "host.kvStorage MUST partition values by tenant. Cross-tenant reads MUST return not-found."
  conformance_test: "kv-cross-tenant-isolation.test.ts"

Mirrors the existing agentMemoryCrossTenantIsolation invariant.

§D Conformance

kv-cross-tenant-isolation.test.ts: set under tenant A, get under tenant B → not found.
kv-atomic-increment.test.ts: 1000 concurrent +1s → final value is 1000.
kv-cas.test.ts: stale expect rejected.
kv-ttl-expiry.test.ts: TTL honored within 1s drift.

Compatibility

Additive. Optional capability; core.openwop.storage kv-\* nodes refuse registration on hosts that don't advertise it.

Implementation notes (non-normative)

Schema diff in §A lands in schemas/capabilities.schema.json on Active promotion, not at Draft.
SECURITY invariant kv-cross-tenant-isolation lands in SECURITY/invariants.yaml alongside the matching scenario; mirrors the existing agent-memory-cti-1 pattern.
Reference impl candidate: in-memory Map per tenant in examples/hosts/in-memory/.

Acceptance criteria

[x] Capability block.
[x] host-capabilities.md §host.kvStorage section. (Landed at commit c5831fe.)
[x] Invariant + 4 scenarios.
[x] In-memory reference host implementation.
[x] CHANGELOG entry.

References

Make Data Store (prior art).
agentMemoryCrossTenantIsolation (existing isolation pattern).
core.openwop.storage pack.

Host.kvStorage capability