[Feature]: Adopt OKF v0.2 output (generated/sources frontmatter, okf_version bump)

[JHSeo-git]

Summary

Google's knowledge-catalog has published OKF v0.2 (SPEC.md). OpenWiki currently produces OKF v0.1 bundles: the bundle-root index.md declares okf_version: "0.1" (src/okf/index-sync.ts), the agent prompts instruct the v0.1 frontmatter schema (src/agent/prompts/code.ts), and the deterministic validator checks the v0.1 field set including timestamp (src/okf/frontmatter.ts).

This issue proposes updating OpenWiki's OKF output to target v0.2.

Motivation

OKF v0.2 supersedes v0.1 and makes provenance, trust, and lifecycle first-class — exactly the questions consumers ask of an agent-maintained corpus like an OpenWiki wiki: what was this generated from, by whom/what, and is it still fresh?

Changes in v0.2 that affect OpenWiki as a producer (SPEC §13):

• Breaking: timestamp is superseded by generated: { by, at } (§5.2). OpenWiki currently recommends and validates timestamp.
• Breaking: the body # Citations list is superseded by the sources frontmatter field (§5.1). (OpenWiki does not emit # Citations, so this is only an opportunity, not a migration.)
• Additive: sources with per-source credibility signals, verified, status, stale_after, the actor convention (<producer>/<version>, §7), a new Attested Computation concept type (§10), and okf_version: "0.2" in the bundle-root index.md.

v0.2 is a minor bump: a v0.1 bundle remains consumable by v0.2 consumers via the documented fallbacks, so the migration is low-risk for existing wikis.

Proposed Solution

Phase 1 — core producer/validator update (this is the bulk of the change):

1. Declare okf_version: "0.2" in the bundle-root index.md (src/okf/index-sync.ts).
2. Replace timestamp with generated: { by, at } in the prompt frontmatter templates and the deterministic frontmatter pass, using the actor convention (e.g. by: openwiki/<version>). Keep tolerating a legacy timestamp when reading existing v0.1 pages, per the SPEC's consumer fallback.
3. Update the deterministic validator (src/okf/frontmatter.ts) for the v0.2 field families, staying permissive per §11 (never reject on missing optional families or unknown keys).

Phase 2 — provenance (natural fit, could be same PR or follow-up):

4. Emit sources on generated concepts. OpenWiki's existing openwiki.source_paths producer extension already tracks this evidence, so it can inform the standard sources field.

Out of scope for now (optional families a producer may omit): verified, status/stale_after, and the Attested Computation concept type. These can be follow-ups if there is interest.

I'm happy to submit a PR for this.

Alternatives Considered

• Stay on v0.1: works, but v0.2 supersedes it and downstream consumers will increasingly expect generated/sources; the longer prompts and validator target v0.1, the more regenerated wikis accumulate superseded timestamp fields.
• Jump straight to full v0.2 including verified/attestation: the trust and attestation families need product decisions (who verifies, what executor/attester means for a wiki), so keeping the first change to the mechanical producer/validator update seems safer.

Additional Context

• OKF v0.2 spec: https://github.com/GoogleCloudPlatform/knowledge-catalog/blob/main/okf/SPEC.md (§13 "Changes from v0.1", §12 versioning)
• Prior OKF work in this repo: Add optional Open Knowledge Format (OKF) output #84, feat: implement okf v0.1 as standard wiki format #263, fix: align okf output with google v0.1 #373