Replace LibStringSet with LibMemoryKV

[thedavidmeister]

What

src/lib/LibStringSet.sol is deleted. Its sixteen call sites use LibMemoryKV
from rain-lib-memkv 0.1.4, newly pinned, which is the org's memory key/value
store.

A string becomes a key as its content hash. A list becomes a set by folding
set over it from an empty store, and a question is has, the bool read added
in rainlanguage/rain.lib.memkv#28. Where a test asks the same list more than
once the set is built once; a both-direction pair builds one set per side.

Why

Nothing about whole-string membership is deploy machinery. The library arrived
here as a test helper, was promoted into the published source tree when the
snapshot verifier needed it, and was the only file in that tree with no deploy
semantics. Every consumer of this package received it.

It was also not the only copy. raindex hand-rolls the same nested scan twice in
its own build test, which is the second consumer that makes this a primitive
rather than a helper.

The store is the right home because a set is a map whose values carry nothing.
It is audited, it is already a dependency of rainlang, and its lookup is a
linked list spread across fifteen of them rather than a linear scan. Nothing in
this diff walks a list or compares a key, so a lookup bug is a bug there, under
that library's own tests, rather than a second implementation of the same idea
kept in step by hand.

No replacement helper was added, in src or in test. The fold sits at each
call site, because the point of the change is to remove a library rather than
move one.

QA

• Discriminating tests: none added. This is a substitution behind sixteen
  existing assertions, whose messages and meanings are byte-identical before and
  after. The tests that already covered each site are named in the table below,
  and they are the discriminators: each fails under a mutation of the fold that
  replaced the call.
• Mutations applied: fifteen, all KILLED, table below. Read the two groups
  differently. M01 and M02 target src/abstract/RainDeployVerifySnapshot.sol
  and are coverage evidence in the ordinary sense. M03 to M15 target folds that
  now sit inside test files, so breaking one makes that test fail by
  construction. They are EXECUTION PROBES, not coverage: each shows its
  converted site is reached and that the surrounding assertion depends on the
  set being built correctly. Counting them as coverage would overstate this
  change, which adds no test.

mutation	target	verdict	killed by
M01 supported-network fold records nothing	src	KILLED	testSupportedNetworksAreFullyConfigured
M02 supported-network fold skips the first network	src	KILLED	testSupportedNetworksAreFullyConfigured
M03 frozen-name fold records nothing	test	KILLED	testSnapshotContractNamesAreTheGeneratedContracts
M04 candidate-side fold records nothing	test	KILLED	testEveryCandidateHasASnapshot
M05 snapshot-side fold records nothing, candidate test	test	KILLED	testEveryCandidateHasASnapshot
M06 snapshot-side fold records nothing, aggregate test	test	KILLED	testEverySnapshotIsInTheReleasedAggregate
M07 aggregate-side fold records nothing	test	KILLED	testEverySnapshotIsInTheReleasedAggregate
M08 record-walk fold records nothing	test	KILLED	testFrozenSnapshotPathsFindsEveryReleaseAndNothingElse
M09 record-walk fold skips the first path	test	KILLED	testFrozenSnapshotPathsFindsEveryReleaseAndNothingElse
M10 rolling snapshot seeded into the set it must be absent from	test	KILLED	testFrozenSnapshotPathsExcludesTheRollingSnapshot
M11 nested-release fold records nothing	test	KILLED	testFrozenSnapshotPathsIgnoresWhatIsNestedInsideARelease
M12 loose-in-root fold records nothing	test	KILLED	testFrozenSnapshotPathsIgnoresAFileLooseInTheRoot
M13 multi-contract freeze fold records nothing	test	KILLED	testFreezeCutsEveryNamedContract
M14 multi-contract freeze fold skips the first record entry	test	KILLED	testFreezeCutsEveryNamedContract
M15 append-freeze fold records nothing	test	KILLED	testFreezeLeavesEarlierReleasesAlone

Probe suite excluded the fork tests, so a rate-limited endpoint could not be
scored as a kill. Its baseline was green at 419 passed.

• Oracle: the NatSpec on the store's get, which states that a key set to zero
  and a key never set are indistinguishable by value and that existence must be
  read separately. That is why every member is stored against a zero value and
  every question reads has rather than comparing a value.
• Category check: the ask was to take the string library out of this repo. It is
  gone from src, from test, and from every other reference: REUSE metadata,
  the slither configuration, the workflows and the README were all checked and
  hold none. No helper replaced it.
• Evidence: the whole suite including fork tests, run twice on the final tree,
  481 passed, 0 failed, 0 skipped across 22 suites. The run before the change
  showed 18 failures, every one an HTTP 429 from a public endpoint.

🤖 Generated with Claude Code

https://claude.ai/code/session_01V8ViHcKLVk2YoS2joH4HdN

Summary by CodeRabbit

• Bug Fixes

  • Improved validation of configured RPC and verification network names, helping identify unsupported network configuration earlier.

• Refactor

  • Updated internal network and snapshot membership handling for more efficient and consistent checks.
  • Removed the legacy string-set implementation.

• Chores

  • Added the memory key-value library dependency required by the updated validation and snapshot processing.

[coderabbitai]

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⛔ Files ignored due to path filters (1)

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📒 Files selected for processing (7)

• foundry.toml
• remappings.txt
• src/abstract/RainDeployVerifySnapshot.sol
• src/lib/LibStringSet.sol
• test/script/Build.t.sol
• test/src/lib/GeneratedSnapshotShape.t.sol
• test/src/lib/LibRainDeploySnapshot.t.sol

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• src/lib/LibStringSet.sol

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---

Walkthrough

The project adds rain-lib-memkv and replaces LibStringSet membership checks with hashed MemoryKV sets in production validation and snapshot-related tests. The local LibStringSet library is deleted.

Changes

MemoryKV membership migration

Layer / File(s)	Summary
Dependency and production membership migration foundry.toml, remappings.txt, src/abstract/RainDeployVerifySnapshot.sol, src/lib/LibStringSet.sol	The project adds the rain-lib-memkv dependency and remapping. Network configuration checks use hashed MemoryKV lookups. LibStringSet is removed.
Test membership migration test/script/Build.t.sol, test/src/lib/GeneratedSnapshotShape.t.sol, test/src/lib/LibRainDeploySnapshot.t.sol	Snapshot, generated-contract, and path assertions build hashed MemoryKV sets and use has for membership checks.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Refactor

Suggested reviewers: claude

Merge Risk: ⚪ Minimal · up to 3f23d

The membership migration has no established correctness or merge-blocking risk.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and concisely describes the main change: replacing the deleted LibStringSet library with LibMemoryKV across the project.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 2026-09-15-string-set-to-memkv

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