FR-5: Attestation Reports & Provenance — cryptographically signed attribution evidence export

[jonesd]

Overview

Provenance and attestation answer: who wrote what, when, and can we prove it?

• Provenance (interactive, DONE): Real-time visibility into document authorship, transclusion ancestry, and chain integrity.
• Attestation (exportable, Phase 1 DONE): A cryptographically signed, standalone document freezing attribution state at a point in time — for legal evidence, regulatory compliance, and IP disputes.

Current State

Done

• Provenance panel: left rail icon, bottom split view, compact/expandable attribution section
• Attribution loading for all users (including anonymous)
• Materialization forced before attribution queries (typed text attributed)
• Attestation report generation (Phase 1 backend): server collects attribution data, signs with Ed25519

TODO

• Phase 2: Frontend export button + JSON download + HTML preview
• Phase 3: Independent verifier CLI (xudanu-cli verify-report)
• Phase 4: RFC 3161 external timestamping (future)
• Phase 5: Federation witnessing — multi-peer cross-verification (future)

Trust Level Framework

Level	Guarantees	Status
1 Basic	Ed25519 spans, BLAKE3 storage, chained log	✅ Current
2 Hardened	Physical security, HSM, NTP	Manual
3 Legal (RFC 3161)	External TSA timestamps	Future
4 Maximum (Federation)	Multi-party witnessing, threshold sigs	Future

Federation Witnessing

In a federated cluster, each peer generates its own signed report. All reports should contain the same attribution data (CRDT convergence) but with different server signatures. Courts/auditors can cross-verify.

Full spec: docs/dev/FR-5.md

Ref: #57 (original issue), #60 (FR-4 links), #35 (CRDT sync)