Infra: Blockchain Evidence Anchor

The blockchain evidence anchor is a Legal & Compliance infrastructure capability that publishes cryptographic hashes of Fox case card generations to a public L2 blockchain. It produces tamper-evident, timestamped proof that a case record existed in a specific state at a specific time — non-repudiable by any party including GrowDirect.

Purpose

Fox's INSERT-only hash-chain provides strong internal evidence integrity. But an internal chain, however disciplined, is controlled by the platform operator — a determined adversary could theoretically replace the whole chain. Anchoring hashes to a public blockchain removes that attack surface entirely. The chain of custody becomes mathematically provable to any third party: a court, an insurer, a regulatory auditor, or a retail enterprise buyer's legal team.

The economics are viable at SMB scale. Anchoring hashes (not data) at Fox case event frequency costs sub-cent per transaction on Base, Polygon, or Arbitrum. A high-volume SMB retailer generating 500 case events per month pays under $5/month in gas. This is not a scaling problem.

What Gets Anchored

Only hashes are anchored — never case content, PII, or operational data.

Event	Hash Input	Anchor Trigger
Card generation	`SHA-256(card_body + frontmatter + generated_at)`	On every `hawk_cards` INSERT
Case status transition	`SHA-256(case_id + old_status + new_status + occurred_at)`	On every `hawk_timeline` status_change event
Evidence chain close	`SHA-256(fox_case_id + final_hash_chain_value + closed_at)`	On Fox case closure linked to Hawk

The blockchain transaction stores: the hash, the case_id (not case content), the event type, and the platform-signed timestamp. That's it. No PII. No investigation detail. No SKU data.

Chain Architecture

Fox Case Event (card generation, status change, closure)
  → Legal & Compliance Agent (hash computation + anchor decision)
    → L2 Blockchain Transaction (hash + case_id + event_type + timestamp)
      → Transaction receipt stored in hawk_timeline
        (event_type: 'evidence_anchored', event_data: {tx_hash, block_number, chain_id})

The transaction receipt written back to hawk_timeline closes the loop — the platform has proof of the anchor, and the blockchain has the hash. Both are independently verifiable.

Network Selection

Preferred: Base (Coinbase L2) or Polygon PoS. Selection criteria: - Sub-cent transaction cost at current gas prices - EVM-compatible (standard tooling, no custom SDK) - Sufficient decentralization to be credible as a neutral third party in litigation - Long-term availability commitment appropriate for evidence retention periods

The Legal & Compliance agent holds the platform signing key used for anchor transactions. Key management follows the Security infrastructure agent's rotation and custody protocols.

Use Cases

Use Case	Beneficiary
LP court proceedings	Case evidence is timestamped and non-repudiable — stronger than internal logs for criminal prosecution support
Insurance claims	Anchored timeline proves the sequence of events for property/theft insurance claims without requiring the insurer to trust GrowDirect's internal records
PCI DSS audit	Demonstrates continuous, tamper-evident audit trail enforcement without manual attestation
GDPR right-to-delete	Anchor proves when data was deleted (or anonymized) — the hash of the deletion event is permanent even after the data is gone
Enterprise buyer due diligence	A blockchain-verifiable evidence chain is a material differentiator in enterprise retail procurement; procurement and legal teams recognize it without explanation

Invariants

The anchor writes a hash only. It never reads or writes case content to the blockchain.
The Legal & Compliance agent is the sole authority for anchor transaction submission. No other agent submits blockchain transactions.
Anchor failures are non-blocking. If the L2 is congested or unavailable, the case event proceeds normally and the anchor is queued for retry. Case operations do not wait on blockchain confirmation.
Anchor receipts (tx_hash, block_number) are stored in hawk_timeline as append-only events. They are never modified.
The platform signing key is rotated per the Security agent's key management schedule. Old keys are retained for receipt verification; only the current key signs new anchors.

signal-civil-services — court-admissible evidence chain is the downstream beneficiary of anchored LP cases
local-market-agent — ORC and flash mob cases that reach civil services are the highest-value anchor targets