feat: update to Effect 4 RC

[tbinna]

Closes #8

What changed

• accept compatible Effect peers from ^4.0.0-rc.109 while keeping the development dependency and packed-consumer smoke fixture pinned to exact RC 109
• update the lockfile and remove transitive packages no longer used by Effect RC
• align installation guidance with the widened Effect 4 peer contract
• rename the consumer migration guide to migration-v3.md and correct stale package-major v2 references to v3 across the README, ADR, rewrite plan, packaging, smoke fixture, and type-contract comments

Compatibility review

The previous baseline was 4.0.0-beta.107. I reviewed the official Effect 4 RC announcement, migration guide, and the Effect changelog through 4.0.0-rc.109. The relevant breaking change is the removal of the standalone SchemaError module in favor of Schema.SchemaError; this library already uses the namespaced API, so no source change was required.

The peer range accepts RC 109 and newer compatible Effect 4 releases, including stable 4.x releases, while excluding earlier RCs and Effect 5. The exact development and smoke-test dependency keeps RC 109 as the reproducible supported baseline.

The remaining stamp and validate v2 text in the rewrite plan refers to stored-data representation version 2, not package major version 2.

Verification

• npm run build
• npm run typecheck
• npm test (68 tests)
• npm run lint
• npm run prettier
• npm run smoke:package
• amended two-axis standards/spec review (0 findings)

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: e7aeb02a-00e2-4d68-9fd8-168737cb7076

📥 Commits

Reviewing files that changed from the base of the PR and between 716a74f and 0471d35.

⛔ Files ignored due to path filters (1)

• package-lock.json is excluded by !**/package-lock.json

📒 Files selected for processing (8)

• README.md
• docs/adr/0007-release-v2-without-a-prerelease-line.md
• docs/adr/0007-release-v3-without-a-prerelease-line.md
• docs/migration-v3.md
• docs/plans/effect-v4-rewrite.md
• package.json
• scripts/package-smoke.mjs
• test/type-contracts.ts

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 931ca468-5354-4374-8285-a381e7c59e55

📥 Commits

Reviewing files that changed from the base of the PR and between 6273cd7 and 716a74f.

⛔ Files ignored due to path filters (1)

• package-lock.json is excluded by !**/package-lock.json

📒 Files selected for processing (4)

• README.md
• docs/migration-v2.md
• package.json
• scripts/package-smoke.mjs

---

📝 Walkthrough

Walkthrough

The pull request updates Effect from 4.0.0-beta.107 to 4.0.0-rc.109 in package metadata, documentation, and the package smoke test.

Changes

Effect 4 release candidate alignment

Layer / File(s)	Summary
Update Effect version references package.json, README.md, docs/migration-v2.md, scripts/package-smoke.mjs	Development, peer, documented, and smoke-test Effect references now use 4.0.0-rc.109.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 716a7

This PR updates the Effect dependency and aligns installation and package-consumer guidance; no actionable merge-blocking risk remains beyond normal checks and review.

Possibly related PRs

• toolsplus/json-evolutions#7: Updates the same Effect version references across dependencies, documentation, and the package smoke test.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Linked Issues check	❓ Inconclusive	The visible changes align with issue #8, but the required package-lock.json update cannot be verified because the file was excluded by path filters.	Include package-lock.json in the review or provide evidence that it was updated to Effect 4.0.0-rc.109.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Out of Scope Changes check	✅ Passed	The documented changes support the Effect 4 release-candidate update and do not show unrelated scope.
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 describes the main change: updating the project to the Effect 4 release candidate.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

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[tbinna]

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[tbinna]

@coderabbitai The requested dependency evidence is already present, so I am not making an additional code change:

• package-lock.json pins the root development and peer dependency to effect@4.0.0-rc.109 and records the public-registry tarball URL plus integrity hash under node_modules/effect.
• npm view effect dist-tags resolved the public rc tag to 4.0.0-rc.109.
• npm install --save-dev --save-exact effect@4.0.0-rc.109 completed successfully from the public registry.
• npm run smoke:package packed this library, installed that tarball together with exact effect@4.0.0-rc.109 in a fresh temporary consumer, compiled and executed both published examples, and passed.

This directly satisfies the availability concern and the inconclusive package-lock check.

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For best results, initiate chat on the files or code changes.

@tbinna The supplied evidence resolves the dependency availability concern.

package-lock.json, the public rc dist-tag, the exact installation, and npm run smoke:package provide sufficient verification for effect@4.0.0-rc.109. No additional code change is required.

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[tbinna]

CodeRabbit follow-up completed on final commit de0a437:

• clarified that the legacy migration snippet is schematic and its placeholders are intentionally application-specific;
• made the ADR explicitly distinguish the historical effect@4.0.0-beta.107 pin from the current exact effect@4.0.0-rc.109 contract;
• re-ran typecheck, formatting, and the isolated packed-consumer smoke test successfully;
• final CodeRabbit CLI review raised 0 issues.

No review threads remain open.

[github-actions]

🎉 This PR is included in version 3.1.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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