feat: ICloneableFactoryV4 — open-salt deterministic clone interface

[thedavidmeister]

Closes #50 — the interface half of it.

Redesigned in place, 2026-08-20, on the ruling that both deterministic entry
points get an explicit domain tag as the first hashed word, so disjointness is
BY CONSTRUCTION (symmetric two-tag) rather than the asymmetric
"tag only the open-salt side" shape the branch carried before. The prior shapes
are summarised under "What changed and why"; the rest of this description
describes only what is on the branch now.

Re-scoped in place, earlier. This PR was opened 2026-08-08 against the
pre-split tree and eight files. #47
then slimmed this repo to an interfaces-only library, deleting src/concrete/,
src/lib/LibCloneFactoryDeploy.sol, src/generated/, script/ and the concrete
tests into
rain.factory.deploy.
main is merged in (merge, not rebase). What is left is the interface and its
doc entries:

file
src/interface/ICloneableFactoryV4.sol	new
src/interface/ICloneableFactoryV3.sol	one @dev pointer added (below)
CLAUDE.md	the V4 architecture entry
README.md	the V4 interface entry

The interface

ICloneableFactoryV3 is published, so the two new functions go on a new
ICloneableFactoryV4, which extends V3 (nothing was dropped, so it inherits
rather than restates):

bytes32 constant ICLONEABLE_FACTORY_V4_NAMESPACED_DOMAIN =
    keccak256("rain.factory.clone.namespaced");
bytes32 constant ICLONEABLE_FACTORY_V4_OPEN_SALT_DOMAIN =
    keccak256("rain.factory.clone.opensalt");

function cloneDeterministicOpenSalt(address implementation, bytes calldata data, bytes32 salt)
    external returns (address);
function predictDeterministicAddressOpenSalt(address implementation, bytes calldata data, bytes32 salt)
    external view returns (address);

Both derivations are now pinned to exact bytes. Each effective CREATE2 salt is
a keccak256 over a 96-byte preimage whose FIRST word is a distinct,
string-derived domain tag the caller cannot set:

// namespaced: cloneDeterministic / predictDeterministicAddress
keccak256(abi.encode(ICLONEABLE_FACTORY_V4_NAMESPACED_DOMAIN, msg.sender, salt))

// open-salt: cloneDeterministicOpenSalt / predictDeterministicAddressOpenSalt
keccak256(abi.encode(ICLONEABLE_FACTORY_V4_OPEN_SALT_DOMAIN, salt, keccak256(data)))

msg.sender is in the namespaced derivation and out of the open-salt one;
data is in the open-salt derivation and out of the namespaced one. Both domain
constants are string-derived and purpose-named — the literal string is the
documentation — following the ICLONEABLE_V2_SUCCESS pattern already in this
repo.

V3 mandates only the msg.sender namespacing as a property, not exact bytes,
so a tagged namespaced derivation still satisfies V3; V4 additionally pins the
whole preimage of both derivations. A one-line @dev pointer is added to V3's
cloneDeterministic NatSpec so a V4 factory's namespaced-derivation bytes are
discoverable from V3; V3's contract is otherwise untouched.

What the two derivations actually differ in

Not "sender or no sender" — what the clone's address commits to:

• cloneDeterministic commits to WHO deployed and not to WHAT. Nobody but that
  account can reach that address, and in exchange the deploying account is baked
  into the address forever — retire it and every address derived from it is
  unreachable. data is outside the derivation, so the deployer alone decides
  the initial state at an address that says nothing about it.
• cloneDeterministicOpenSalt commits to WHAT and not to WHO. Every account
  reaches the same address, and so can anyone — but everyone who reaches it
  deploys the same contract initialized with the same bytes, because varying
  either input lands somewhere else.

Neither dominates, and the interface says so. Open-salt's real cost is stated
too: the address is not knowable until data is final, and re-deploying "the
same" clone with corrected data is a different address. A consumer pinning an
open-salt address must reproduce the exact data bytes, ABI encoding and all.

Front-running is closed by the signature, not by an audit

Without msg.sender namespacing, anybody can deploy at the open-salt address
first, and clone-and-initialize is atomic and runs once, so first mover is
permanent. That only matters if the first mover has something to vary. With
data inside the derivation they do not:

• different data → different address. The address anyone pinned is untouched;
  the front-runner deployed their own contract at their own address, at their own
  expense.
• same data → the intended contract, initialized with the intended bytes. They
  have paid the gas and nothing else.

That is the position which makes permissionless Zoltu deployment harmless,
reached with arguments by putting the arguments in the address. It is a
property of the signature, so there is no per-implementation "could a squatter
pass something worse" audit to get wrong.

The residual, which the NatSpec states as MUST NOT

The address fixes data. It cannot fix what initialize reads that is not
data, so the deployer keeps exactly one lever: when the deploy lands, and
therefore which chain state initialize observes.

• The implementation MUST NOT read tx.origin, directly or through anything it
  calls during initialization. That is the one remaining channel from deployer to
  initial state. (msg.sender during initialize is the factory — the same for
  every caller, therefore harmless.)
• Everything else initialize resolves from chain state resolves identically for
  every caller at a given block. The address registry
  (Address registry: interface, concrete, reader lib and post-deploy cross-network verification rain.deploy#26) is the intended shape: initialize resolves the
  admin by NAME, and the name — being part of data — is committed to by the
  address. While the name is unbound the registry read reverts, so the
  front-running window only opens once the binding exists.
• Registry-resolved authority is now the ordinary case: it is data that
  names things instead of naming addresses, and an implementation that resolves
  everything from the registry passes empty data.

Disjointness is now BY CONSTRUCTION, from two distinct first-word tags

The open-salt guarantee holds only while no other entry point on the same
factory can CREATE2 at an effective salt in the open-salt image with
caller-supplied data. The inherited cloneDeterministic is exactly such an
entry point — it takes arbitrary data — so the two derivations MUST NOT share
an effective-salt image.

They do not, and the reason no longer leans on either a preimage length or the
shape of a salt value:

• Both preimages are 96 bytes whose FIRST word is a fixed domain tag no caller
  can set. cloneDeterministic leads with ICLONEABLE_FACTORY_V4_NAMESPACED_DOMAIN;
  cloneDeterministicOpenSalt leads with ICLONEABLE_FACTORY_V4_OPEN_SALT_DOMAIN.
• The two constants are distinct keccak256 outputs, so the two preimage sets
  are disjoint in their first word alone.
• A caller on the namespaced path chooses only words 1 and 2 (msg.sender,
  salt); a caller on the open-salt path only words 1 and 2 (salt,
  keccak256(data)). Neither can place the other derivation's tag in word 0, so
  neither can aim its entry point at an address the other produces.

The interface states this disjointness as a MUST NOT on the factory, which is
checkable, rather than as advice to consumers, which is not.

Events

NewClone is reused, emitted with the caller-supplied salt — not the effective
salt. Its sender field is not part of the open derivation, but salt and
data together are the whole of it, so the event still carries the full
deterministic deploy that ICloneableFactoryV3.NewClone promises. An indexer
that wants to verify rather than trust the emitted address picks the derivation
by trying both and keeping the match — well defined, because the two tags mean
they cannot both produce the emitted clone.

Cross-network determinism, unchanged and still not claimed unconditionally

CREATE2 hashes the factory, and the EIP-1167 creation code it hashes contains
the implementation, so an open-salt clone is at the same address on two chains
only where BOTH are. Dropping msg.sender removes a third thing that has to
match; it does not make the other two match.

What changed and why

This interface has never published — 0.1.6 is interfaces-only and predates it —
so nothing here is a breaking change to a consumed interface. It has been
redesigned in place twice:

1. verbatim salt → hash data in, msg.sender out (2026-08-13). The
   open-salt address now encodes data, which is what collapses the old
   ~50-line "audit initialize for authority taken from data" NatSpec into a
   tx.origin MUST NOT plus a timing residual. predictDeterministicAddressOpenSalt
   gained its data parameter here.
2. asymmetric single tag → symmetric two tags (this revision). Previously
   only the open-salt preimage carried a domain tag and the namespaced side was
   keccak256(abi.encode(msg.sender, salt)) (64 bytes, untagged); disjointness
   was argued from "the open-salt preimage is 96 bytes not 64, and its first word
   is a hash not a left-padded address." That argument is now obsolete. The
   namespaced side gets its own explicit tag as word 0, both preimages are 96
   bytes, and disjointness follows from the two distinct fixed tags alone — no
   reasoning about lengths or which salt values look like an address. The
   open-salt domain string is also renamed from the opaque
   "ICloneableFactoryV4.cloneDeterministicOpenSalt" to the purpose-named
   "rain.factory.clone.opensalt", paired with the new
   "rain.factory.clone.namespaced".

Reaches the deploy PR

Yes — rainlanguage/rain.factory.deploy#8 must change
with this and cannot merge as written. BOTH effective-salt computations move
now, not just the open-salt one: CloneFactory.cloneDeterministic /
predictDeterministicAddress must adopt the tagged namespaced derivation
keccak256(abi.encode(ICLONEABLE_FACTORY_V4_NAMESPACED_DOMAIN, msg.sender, salt)),
and the open-salt pair must adopt the renamed
ICLONEABLE_FACTORY_V4_OPEN_SALT_DOMAIN value. Concretely it needs: both
effective-salt computations, src/generated/candidate/CloneFactory.pointers.sol
regenerated (the bytecode changes, so the pinned address and codehash move),
.gas-snapshot regenerated, and its fuzz tests reworked — the disjointness test
now asserts the two-tag construction (distinct first words) rather than the old
length/left-padded-address squat, and it still owes the "different data at the
same salt → different address" property. Its README/CLAUDE entries describe the
old derivation. That PR is blocked on this one publishing rain-factory 0.1.7 —
it pins and imports rain-factory-0.1.7/src/interface/ICloneableFactoryV4.sol,
with no vendored copy on that side.

Release

rainix-autopublish runs on merge. main is merged in here, which brings in the
post-rainix#336 flow: the published version is derived from the registry, not
pinned in foundry.toml (main dropped the [package] metadata). A content
change therefore publishes the next version after the latest on the registry —
0.1.6 today, so 0.1.7. That publish is what unblocks the deploy PR.

CI

rainix-sol / test, static and legal on the branch. There are no fork tests
and no RPC secrets here; rainix-sol-test runs and finds nothing, by design —
an interface declares no behaviour, so every discriminating test for this
contract runs against the concrete in the deploy PR.

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---

Walkthrough

The PR adds ICloneableFactoryV4 with open-salt deterministic cloning and address prediction. It documents salt derivation, initialization requirements, interface inheritance, repository boundaries, and legacy interface status.

Changes

Open-salt deterministic cloning

Layer / File(s)	Summary
V4 contract and repository guidance src/interface/ICloneableFactoryV4.sol, src/interface/ICloneableFactoryV3.sol, CLAUDE.md	Defines the V4 interface, domain-separated salt constants, V3 inheritance, derivation rules, initialization requirements, and repository dependency boundaries.
Open-salt deployment and prediction src/interface/ICloneableFactoryV4.sol	Adds open-salt deployment and prediction methods. The derivation commits to initialization data and excludes caller identity.
Supporting interface documentation README.md	Describes V4 open-salt semantics and clarifies V3, V2, legacy factory, initialization, and warning documentation.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to bc3d6

The PR is merge-ready after normal checks and review; one localized README wording issue remains as a minor documentation follow-up.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The PR adds the V4 interface, open-salt clone and prediction functions, domain separation, data commitment, atomic initialization, and required safety documentation for issue #50.
Out of Scope Changes check	✅ Passed	The changes are limited to the V4 interface and related README, architecture, and derivation documentation.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely identifies the main change: adding the ICloneableFactoryV4 open-salt deterministic clone interface.

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• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch factory/open-salt-clone

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Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@README.md`:
- Around line 16-20: Update the cloneDeterministicOpenSalt documentation to make
cross-chain address portability conditional: the same raw salt yields the same
address only when both the factory and implementation addresses match across
chains, since CREATE2 incorporates the factory and the EIP-1167 initialization
code incorporates the implementation. Preserve the existing security guidance
about caller-controlled authority.

In `@test/src/lib/LibCloneFactoryDeployTaggedConstants.t.sol`:
- Around line 123-135: Update _containsSelector so it verifies the selector is
reachable through executable dispatcher logic rather than merely matching bytes
anywhere in code. Decode the runtime dispatcher, or deploy the frozen runtime
and invoke each expected selector with valid arguments, and preserve the test’s
failure behavior when an entry point is unavailable.

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• test/src/lib/LibCloneFactoryDeployTaggedConstants.t.sol

[thedavidmeister]

🤖 ai:producer
Blocked-on: repo not migrated to the split release lifecycle: the five testProdDeploy* fork tests in test/src/lib/LibCloneFactoryDeployProd.t.sol assert the single current pin LibCloneFactoryDeploy.CLONE_FACTORY_DEPLOYED_ADDRESS has code on Arbitrum, Base, Base Sepolia, Flare and Polygon. This PR changes CloneFactory bytecode, so it necessarily repoints that pin from src/generated/0_1_5 to src/generated/0_1_6; 0.1.6 is generated by this PR and is not on chain anywhere, so rainix-sol / test / test stays red until an out-of-band deploy. There is no code fix on the branch: not bumping the pin would leave the current pin naming bytecode that lacks the new open-salt entry points. Producer deploys nothing (#162). Verified locally in the repo's own toolchain (rainix sol-shell @53e96a7, forge test --no-match-path test/src/lib/LibCloneFactoryDeployProd.t.sol): 29 passed, 0 failed, so the prod pin is the only red.
blocked-by #46

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Inline comments:
In `@README.md`:
- Around line 34-35: Update the README sentence to use the standard hyphenated
spelling “self-destruct” instead of “self destruct,” leaving the surrounding
wording and link unchanged.

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