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feat: Shadow Accounts — cross-chain smart account presence via interop#2112

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feat: Shadow Accounts — cross-chain smart account presence via interop#2112
valera-grinenko-ai wants to merge 9 commits intomatter-labs:draft-v32from
valera-grinenko-ai:shadow-accounts

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@valera-grinenko-ai valera-grinenko-ai commented Apr 3, 2026 •
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Summary

Implements Shadow Accounts as a standalone protocol building block on draft-v32. A Shadow Account is a smart account deployed on a remote chain via interop, giving a home-chain user contract interaction capabilities there without an EOA or separate deployment.

Primary use cases (from spec):

  • Origin-routed private interop (B→A→C): ShadowAccount on the origin chain automates the A→C relay leg within a single user transaction on B.
  • L2→L1 interop: ShadowAccount on L1 lets an L2 user interact with L1 contracts (governance, DeFi) without a separate L1 account.

What this PR adds

New contracts (l1-contracts/contracts/interop/):

  • ShadowAccount.sol — ERC-7786 recipient with two-layer authorization (InteropHandler as caller, ERC-7930 owner as sender). Executes ShadowAccountCall[] payloads supporting both call and delegatecall (for script contracts that read remote state). Caches keccak256(owner) at initialization for gas-efficient authorization.
  • ShadowAccountFactory.sol — CREATE2 deployer. One account per owner per chain. Salt = keccak256(ERC-7930 encoded owner) ensures deterministic addresses without querying the target chain. predictAddress is public for gas-efficient internal use.
  • IShadowAccount.sol, IShadowAccountFactory.sol — Interfaces and data types.

Modified contracts:

  • InteropHandler._executeCalls — When interopCall.shadowAccount == true, routes through the sender's ShadowAccount (lazy-deploying via factory) instead of calling interopCall.to directly.
  • InteropCenter — Parses new shadowAccount(bool) ERC-7786 call attribute; enforces mutual exclusion with indirectCall; propagates flag to InteropCall.
  • IERC7786Attributes — Added shadowAccount(bool) attribute declaration.
  • CallAttributes struct — Added bool shadowAccount field (packed with indirectCall for storage efficiency).
  • Config.sol — SUPPORTED_INTEROP_ATTRIBUTES 5 → 6.
  • L2ContractAddresses.sol — L2_SHADOW_ACCOUNT_FACTORY_ADDR at 0x10012.
  • L2ContractInterfaces.sol — L2_SHADOW_ACCOUNT_FACTORY interface constant.
  • InteropErrors.sol — Six new shadow account error types (with selectors via errors-lint).

Design decisions

Decision Choice Rationale
Factory address Built-in 0x12 Next slot after L2_BASE_TOKEN_HOLDER (0x11); follows existing pattern
CREATE2 salt keccak256(ERC-7930 owner) Encodes both chain ID and address → one account per owner per chain
No constructors/immutables Initialization pattern Required by zksync OS (per AGENTS.md)
Owner hash caching _ownerHash = keccak256(owner) at init Avoids re-hashing variable-length bytes on every receiveMessage call
shadowAccount + indirectCall Mutually exclusive Fundamentally different routing modes; combining has no defined semantics
interopCall.to when shadow=true Set by user, ignored by InteropHandler Handler overrides routing; to preserved for event logging

What this PR does NOT include

  • BZZK / private interop implementation (follow-up PR).
  • Speculative hooks or unrelated refactors.
  • Changes to GWAssetTracker, L2AssetRouter, or L2AssetTracker.

Test plan

23 new tests in L2ShadowAccountTestAbstract.t.sol / L2ShadowAccountL1Test.t.sol:

  • Factory (5): deterministic deployment, idempotency, different-owner / different-chain addressing, event emission
  • Initialization (3): owner storage, event emission, double-init revert, factory-only access
  • Authorization (3): InteropHandler-only caller, owner-only sender, happy path
  • Call execution (6): value transfers, multi-call sequencing, event emission, failure revert, delegatecall, empty payload edge case
  • ETH reception (1): receive() accepts ETH
  • InteropHandler integration (2): end-to-end shadow account routing via bundle, non-shadow regression
  • Fuzz (2): address uniqueness across owners (256 runs), predict-matches-deploy invariant (256 runs)
  • Regression: all 164 tests pass across 20 suites (0 failures, 0 regressions)

🤖 Generated with Claude Code

@claude
feat: implement Shadow Accounts for cross-chain smart account presence
dd9b22a 
Shadow Accounts give a home-chain user a smart account on remote chains,
enabling automated relay during bundle execution (e.g., origin-routed
private interop B→A→C) and L2→L1 contract interaction without a
separate L1 account.

Core design:
- ShadowAccount implements IERC7786Recipient with two-layer auth:
  msg.sender must be InteropHandler, ERC-7786 sender must match owner.
- ShadowAccountFactory deploys one account per owner per chain via
  CREATE2 (salt = keccak256(ERC-7930 encoded owner)).
- InteropHandler routes calls through shadow accounts when
  InteropCall.shadowAccount is true (lazy deploy via factory).
- New shadowAccount(bool) ERC-7786 call attribute, mutually exclusive
  with indirectCall.
- Supports arbitrary calls and delegatecalls (for script contracts).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Shadow Accounts and others added 2 commits April 3, 2026 22:35
@claude
fix: CI fixes — struct packing, selectors, zkstack-out, slither config
d4809f1 
- Reorder CallAttributes fields for efficient 32-byte slot packing
  (bools grouped together) to satisfy gas-struct-packing lint rule.
- Regenerate selectors and zkstack-out (InteropCenter ABI).
- Exclude delegatecall-loop from Slither — ShadowAccount delegatecall
  targets are chosen by the authenticated owner, not by untrusted input.
- Prettier formatting fixes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@claude
chore: recompute hashes and zkstack-out with foundry-zksync v0.1.5
238e6e6 
Ran recompute_hashes.sh with the expected compiler version
(foundry-zksync-v0.1.5, commit 807f47ace) to regenerate
AllContractsHashes.json and zkstack-out artifacts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Shadow Accounts and others added 6 commits April 4, 2026 08:06
@claude
fix: format shadow account errors with selectors via errors-lint
c3cd162 
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@claude
fix: remove trailing blank line in InteropErrors.sol
93ba9f3 
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@claude
fix: update stale NatSpec, clean up InteropHandler routing, remove un…
469e3aa 
…used helper

- Update InteropCall.shadowAccount NatSpec to reflect implementation
  (was still saying "always false, not yet implemented").
- Simplify shadow account routing in _executeCalls to a ternary.
- Remove unused _buildSingleDelegatecallPayload test helper.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@claude
fix: cache owner hash, make predictAddress public, remove self-call
12f5c3b 
- Cache keccak256(owner) as _ownerHash in ShadowAccount to avoid
  re-hashing variable-length bytes on every receiveMessage call.
- Change predictAddress from external to public so the factory can
  call it internally without an external self-call (this.predictAddress).
- Remove assert in factory — rely on CREATE2 determinism directly.
- Recompute AllContractsHashes.json.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@claude
test: add empty payload edge case test for ShadowAccount
e53d921 
0xValera review pattern: demands edge-case coverage and "checking of
effects of interactions, not just calling functions."

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@claude
test: remove unnecessary mocks from shadow account tests
7fccadb 
- Drop redundant vm.mockCall on call targets — etched STOP opcode
  already makes the call succeed cleanly.
- Replace vm.mockCallRevert with a real AlwaysReverter contract.
- Remove vm.mockCall on the predicted shadow account in the
  InteropHandler integration test — the real CREATE2-deployed
  ShadowAccount now runs receiveMessage end-to-end. Added assertions
  verifying the account is deployed and its owner matches the sender.

The L2_MESSAGE_VERIFICATION mock is kept (matches every other interop
test in the file — cannot remove without a real L2→L1 Merkle proof).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@kelemeno
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kelemeno commented Apr 17, 2026 •
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please point this at #2076 it is a modification of that branch. It also has some other work, which ideally does not get lost

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