[ocakciomursel-pixel]

Fixes #51

Summary

Implements POST /api/v1/acceptance/checkNote in chaincash_server so callers can submit a JSON-encoded ChainCash note and check whether the server accepts it under its configured [acceptance] predicates (Whitelist, Blacklist, Collateral, and recursive Or), returning {"accepted": true|false}.

Key Design Details

1. Supported JSON Note Formats

   • Wallet / Store NoteWithHistory JSON (exact round-trip output of GET /api/v1/notes/wallet and GET /api/v1/notes/byPubkey/:pubkey).
   • Raw Ergo ErgoBox JSON (validated via chaincash_offchain::boxes::Note::from_box, enriching commitment history automatically when the box is already indexed in ChainCashStore).
   • ErgoBox + Explicit Ownership History JSON ({"ergo_box": ..., "history": [...]} or {"box": ..., "history": [...]}): validates the note box contract/registers, reconstructs NoteHistory (supporting both 65-byte hex and byte-array Schnorr signatures), verifies the reconstructed AVL+ digest matches register R4, and cryptographically verifies every reserve signature against blake2b256(note_id_bytes || amount_be_bytes) when the reserve owner pubkey is known.
   • Direct NoteContext JSON ({"owner", "issuer", "nanoerg", "liabilities"}).
   • Malformed payloads, non-note Ergo boxes, mismatched R4 AVL digests, or invalid reserve signatures return 400 Bad Request.

2. Gold-to-NanoErg Valuation & Monotone Oracle Short-Circuiting

   • Note token amounts represent milligrams of gold (gold_amount_mg), whereas reserve values are stored in nanoErg.
   • When evaluating Collateral predicates, note and liability amounts are converted to nanoErg using either a stored Denomination row (when denomination_id is present) or the ChainCash Gold Oracle box (R4 / 1_000_000 nanoErg per mg of gold, matching TransactionService::redeem_note).
   • Because all acceptance predicates (Whitelist, Blacklist, Collateral, Or) are monotone with respect to collateral backing, checkNote first evaluates predicates against a zero-collateral provider and short-circuits immediately when Whitelist / Blacklist / Or branches already accept—avoiding unnecessary Ergo node HTTP calls.

3. Accurate Collateral Accounting & Split-Change Preservation

   • Aggregates unspent reserves per owner pubkey and sums outstanding note liabilities across all stored notes plus the candidate note.
   • Deduplicates an already-indexed candidate note (by ergo_box_id for ErgoBox payloads, or at most one matching stored row for NoteWithHistory payloads) so stored notes are never double-counted while sibling split-change notes sharing the same note_id token identifier remain properly counted in issuer_note_tally.
   • Hardens Blacklist evaluation so unresolved/empty issuer or historical signer pubkeys cannot falsely pass Issuer or Historical blacklist checks, and fixes a nested SQLite pool checkout in NoteRepository::get_by_box_id.

Verification

• cargo fmt --all -- --check
• cargo clippy --all-features
• cargo test (34 passed, 0 failed — including 10 new end-to-end async acceptance::tests covering wallet JSON round-trip, raw ErgoBox, cryptographic Schnorr signature + R4 AVL verification, Gold Oracle conversion, split-change note accounting, intermediate historical signer collateralization, offline-oracle Or short-circuiting, and 400 Bad Request validation)