chore: added CLAUDE.md and AGENTS.md files

Author: frolvanya

AGENTS.md

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+CLAUDE.md

CLAUDE.md

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+## Overview
+
+Rainbow Bridge ETH→NEAR light client. An on-chain Ethereum light client contract on NEAR that tracks Ethereum beacon chain finality via sync committee updates, plus a relayer that feeds it data.
+
+## Repository Layout
+
+Two Cargo workspaces plus a standalone crate:
+
+- **`contracts/near/`** — NEAR smart contracts workspace (`eth2-client`, `eth-prover`, `eth-types`)
+- **`eth2near/`** — Legacy relayer workspace (7 crates)
+- **`relayer/`** — New relayer (standalone, Rust edition 2024)
+
+The eth2 light client lives in `contracts/near/eth2-client/`. Supporting crates:
+- `eth-types` — Ethereum execution/consensus type definitions (BlockHeader, BeaconBlockHeader, SyncCommittee, etc.)
+- `eth2-utility` — Consensus logic: network configs, fork handling, merkle proof verification, sync committee period computation
+- `eth2_hashing` — WASM-compatible Keccak256 (patched ethereum_hashing for NEAR SDK)
+
+## Build, Test, Lint
+
+All contract commands run from `contracts/near/`:
+
+```bash
+# Build (requires cargo-near and wasm32-unknown-unknown target)
+cargo near build reproducible-wasm --manifest-path contracts/near/eth2-client/Cargo.toml
+
+# Test (the canonical CI sequence — builds test WASM first, then runs tests twice: with and without default features)
+cd contracts/near/eth2-client && ./test.sh
+
+# Run all tests
+cd contracts/near && cargo test -p eth2-client
+
+# Run a single test
+cd contracts/near && cargo test -p eth2-client test_gc_headers -- --nocapture
+
+# Unit tests only (no mainnet feature, allows validate_updates=false)
+cd contracts/near && cargo test -p eth2-client --no-default-features -- --nocapture
+
+# Lint
+cd contracts/near && cargo clippy
+cd contracts/near && cargo fmt --check
+```
+
+**Feature flags** (eth2-client): `default = ["logs", "mainnet"]`
+- `mainnet` — enforces `validate_updates` and `verify_bls_signatures` on init
+- `logs` — enables `env::log_str()` output
+- Unit tests marked `#[cfg(not(feature = "mainnet"))]` only run with `--no-default-features`
+
+**CI** (`.github/workflows/contracts-near.yml`): runs `make build-eth2-client`, `./test.sh`, and relayer tests. Requires `git-lfs` for test data.
+
+## Contract State Machine
+
+The eth2-client alternates between two modes:
+
+```
+SubmitLightClientUpdate → submit_beacon_chain_light_client_update()
+    validates sync committee signatures, merkle proofs, period transitions
+    updates finalized beacon header + sync committees
+    → transitions to SubmitHeader
+
+SubmitHeader → submit_execution_header() (called repeatedly)
+    accepts execution blocks in reverse order (newest→oldest)
+    stores block_number→block_hash in LookupMap
+    GCs old blocks beyond hashes_gc_threshold
+    when chain is closed (reaches previous finalized block + 1)
+    → transitions back to SubmitLightClientUpdate
+```
+
+Light client updates can advance by at most 1 sync committee period (8192 slots ≈ 27 hours). This bounds GC to at most one period's worth of removals per cycle.
+
+## Key Protocol Constants
+
+From `eth2-utility/src/consensus.rs`:
+- `SLOTS_PER_EPOCH = 32` (~6.4 min)
+- `EPOCHS_PER_SYNC_COMMITTEE_PERIOD = 256`
+- One sync committee period = 8192 slots ≈ 27 hours
+- `hashes_gc_threshold` is typically 51000 (~7 days of blocks)
+
+## Storage Keys
+
+```rust
+StorageKey::FinalizedExecutionBlocks  // LookupMap<u64, H256> — block number → hash
+StorageKey::FinalizedExecutionHeader  // LazyOption<ExecutionHeaderInfo>
+StorageKey::CurrentSyncCommittee      // LazyOption<SyncCommittee>
+StorageKey::NextSyncCommittee         // LazyOption<SyncCommittee>
+```
+
+`__DeprecatedUnfinalizedHeaders` and `__DeprecatedSubmitters` are leftover from V1 migration — do not reuse.
+
+## Access Control
+
+Uses `near-plugins` for roles: `DAO`, `PauseManager`, `UpgradableCodeStager/Deployer`, `UnrestrictedSubmitLightClientUpdate`, `UnrestrictedSubmitExecutionHeader`. Admin methods (`update_trusted_signer`, `update_hashes_gc_threshold`, etc.) require `Role::DAO`.
+
+## Test Data
+
+Test data lives in `contracts/near/eth2-client/src/data/` (LFS-tracked JSON files). Sepolia is the primary test network. Regenerate with:
+```bash
+cd contracts/near/eth2-client/src/data && uv run dump_sepolia_data.py
+```
+
+## Migration Pattern
+
+`migrate.rs` defines the previous struct version (e.g., `Eth2ClientV1`) and a `migrate()` function that reads old state and constructs the new `Eth2Client`. When adding fields to `Eth2Client`, create a new versioned struct matching the *current* on-chain layout and set defaults for new fields in `migrate()`.
+
+## New Relayer (`relayer/`)
+
+Standalone binary with CLI subcommands: `run` (continuous), `run-job` (single execution for Cloud Run), `init`, `generate-config`, `validate-config`. Config via TOML or env vars with `RELAYER_` prefix. Uses Lighthouse types for beacon chain, Alloy for execution RPC, near-fetch for NEAR.