Publish /api/v1/identity — deployed lens's full hybrid federation key (Ed25519 + X25519 + ML-DSA-65 + ML-KEM-768)

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Why

CIRISAgent 2.9.6 (and any future federation peer) needs the deployed lens's full hybrid federation identity to address it: Ed25519 + X25519 (transport KEX classical) + ML-DSA-65 + ML-KEM-768 (transport KEX PQ). Today there's no published endpoint — consumers would have to compose engine.local_public_key_b64() + engine.local_pqc_public_key_b64() via the internal API + derive X25519 from Ed25519 themselves + have no path to the ml-kem-768 half at all (it lives in the Edge runtime).

This issue covers the lens-side endpoint that publishes the aggregate. It's blocked on two prereqs that have to land first; see "chain" below.

What

GET /api/v1/identity — public, no auth, rate-limited + cached, returns the lens's federation hybrid identity bundle.

{
  "steward_key_id": "lens-steward",
  "steward_pqc_key_id": "lens-steward-mldsa",
  "ed25519_pubkey_b64": "kdtTafS49EAuPD3z8/zhwsoMp5d4LYs/CCZPEowiFUs=",
  "x25519_pubkey_b64": "kogV3xbe0Lh4JiKhiAlCproQrAYJVBZ77DRklrQs9Bw=",
  "ml_dsa_65_pubkey_b64": "GF2uj2PO2/LmUwM...(1952 b64)",
  "ml_kem_768_pubkey_b64": "...(1184 b64)" ,
  "did_key": "did:key:z6Mk...",
  "identity_hash": "sha256:...",
  "evaluated_at_unix_ms": 1750000000000
}

Implementation is a one-liner once the prereqs ship:

# api/identity.py (new module) or a section of accord_api.py
@router.get("/identity")
async def get_lens_identity() -> dict[str, Any]:
    engine = persist_engine.get_engine()
    if engine is None:
        raise HTTPException(503, "persist engine unavailable")
    return json.loads(engine.local_identity_aggregate())

Cache TTL = the lifetime of the worker process (the identity is stable; only changes on Engine re-init with a rotated steward key). Rate limit at the existing scoring-API tier (60/min/IP).

Caddy routing: /api/v1/identity is on the public list alongside /api/v1/accord/* and /api/v1/scoring/*. CLAUDE.md's Caddy section gets the line.

Chain — prerequisites

1. CIRISPersist#198 — Engine.local_identity_aggregate() primitive lands the JSON bundle. Until this exists, the lens has no way to express the four keys in one call without composing two existing accessors + a derivation + a None.
2. CIRISLensCore#43.1 — the host-Engine PyCapsule handshake that makes LensClient (and by extension install_relay) see the wheel-built host Engine. Until this lands, attempting install_relay(edge) in the cohabitation/pip setup throws RuntimeError: no process Engine.
3. CIRISLens#18 §2 — wire init_edge_runtime(engine, ...) + install_relay(edge) into the lens-API startup hook. Until this lands, persist#198's ml_kem_768_pubkey_b64 stays None on the deployed lens (X25519 + Ed25519 + ML-DSA-65 are available unconditionally; ML-KEM-768 needs Edge).

When all three are in, this issue is a ~20-line lens-side patch:

• Add api/identity.py (router) or extend accord_api.py
• Wire into main.py's include_router
• Update Caddyfile + CLAUDE.md "Public accord API" line to list /api/v1/identity

Test plan

• Smoke against a docker-postgres harness with Edge wired: returns the 4-key bundle, all fields populated, identity_hash stable across requests.
• Without Edge wired (pre-Adopt ciris-lens-core 1.0.0 — replace the in-tree cirislens-core; own the wire/scrub contract at the substrate #18 §2): returns the 3-key bundle (ed25519 + x25519 + ml_dsa_65), ml_kem_768_pubkey_b64: null.
• Verify X25519 derivation against the live Ed25519: kogV3xbe0Lh4JiKhiAlCproQrAYJVBZ77DRklrQs9Bw= matches NaCl's crypto_sign_ed25519_pk_to_curve25519 over kdtTafS49EAuPD3z8/zhwsoMp5d4LYs/CCZPEowiFUs=.
• Bridge probe round-trips: curl https://lens.ciris-services-1.ai/api/v1/identity returns the bundle agent 2.9.6 can address against.

References

• CIRISPersist#198 (substrate primitive)
• CIRISLensCore#43 / #43.1 (capsule handshake umbrella; cross-comment added)
• CIRISLens#18 §2 (install_relay deployed-lens wiring)
• CIRISVerify#47 (FederationHandshake X25519 + ML-KEM-768 hybrid KEX with HKDF-SHA256 binding — the wire shape the published identity has to be addressable against)
• CIRISEdge#54 (closed; Edge consumed FederationHandshake on the transport side)