OpenWOP — RFC 0019: host.blobStorage + host.cache capabilities

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

Field	Value
RFC	0019
Title	Blob storage + TTL cache capabilities
Status	`Accepted`
Author(s)	OpenWOP Working Group
Created	2026-05-17
Updated	2026-05-18 (Active → Accepted: all 5 acceptance-criteria items satisfied. 2 capability blocks (`blobStorage`, `cache`) in schema; 2 prose sections (§host.blobStorage / §host.cache) in `spec/v1/host-capabilities.md` landed at commit c5831fe; 2 SECURITY invariants (`blob-cross-tenant-isolation`, `cache-cross-tenant-isolation`) added at commit c5831fe; 5 scenarios (`blob-roundtrip`, `blob-presign-expiry`, `blob-cross-tenant-isolation`, `cache-ttl-expiry`, `cache-cross-tenant-isolation`) all behavioral; reference impls advertised in `routes/discovery.ts` lines 211–222; CHANGELOG entry under `[Unreleased]`.)
Affects	`spec/v1/host-capabilities.md` · `schemas/capabilities.schema.json` · `SECURITY/invariants.yaml`
Compatibility	`additive`

Summary

Adds two sibling capabilities: host.blobStorage (binary artifact store with presigned URLs) and host.cache (TTL cache for HTTP / AI response memoization). Required by core.openwop.storage's blob-_and cache-_ nodes.

Motivation

Workflow editors universally surface object storage (S3 / GCS / Azure Blob) and HTTP response caching as discoverable primitives. The two are small enough and similar enough in shape to share an RFC. host.cache is what lets idempotency-key based replay deduplicate identical AI calls across runs without engaging the heavier Layer-2 invocation log.

Proposal

§A Capability schemas

{
  "blobStorage": {
    "type": "object",
    "properties": {
      "supported": { "type": "boolean" },
      "buckets": { "type": "array" },
      "presignSupported": { "type": "boolean" },
      "maxObjectBytes": { "type": "integer" }
    },
    "additionalProperties": false
  },
  "cache": {
    "type": "object",
    "properties": {
      "supported": { "type": "boolean" },
      "maxValueBytes": { "type": "integer" },
      "maxTtlSeconds": { "type": "integer" }
    },
    "additionalProperties": false
  }
}

§B Host-contract MUSTs

Blob: cross-tenant isolation per bucket. Presigned URLs MUST expire at the advertised TTL.
Cache: TTL drift ≤ 1s on expiry visibility; entries scoped per tenant.

§C Conformance

blob-roundtrip.test.ts.
blob-presign-expiry.test.ts.
blob-cross-tenant-isolation.test.ts.
cache-ttl-expiry.test.ts.
cache-cross-tenant-isolation.test.ts.

Compatibility

Additive. Two optional blocks. Packs refuse registration without advertisement.

Implementation notes (non-normative)

Schema diffs in §A land in schemas/capabilities.schema.json on Active promotion, not at Draft.
Cross-tenant invariants for blob-cross-tenant-isolation + cache-cross-tenant-isolation land in SECURITY/invariants.yaml alongside the matching scenarios.
Reference impl candidate: per-tenant Map for cache; per-tenant Map<bucket, Map<key,buffer>> for blob — both under examples/hosts/in-memory/.

Acceptance criteria

[x] Two capability blocks.
[x] Prose section per block. (Landed at commit c5831fe.)
[x] 5 conformance scenarios.
[x] In-memory reference (per-tenant Map for cache; per-tenant Map<bucket, Map<key,buffer>> for blob).
[x] CHANGELOG entry.

References

AWS S3 / GCS / Azure Blob (prior art for blob).
HTTP Cache-Control / ETag semantics (prior art for cache).
core.openwop.storage pack.

Host.blobStorage + host.cache capabilities