ci: verify the supported Rails and Ruby span

[cardmagic]

Roadmap milestone 8, the compatibility half.

The gap

solid_objects.gemspec advertises Rails >= 8.0 on Ruby >= 3.3, but CI ran exactly one combination: Ruby 3.3 with whatever Rails resolved newest. Rails 8.0 had never been exercised, so the supported range was a claim rather than a tested guarantee. This is the kind of gap that surfaces as a user bug report instead of a test failure.

The change

A compatibility job over Ruby 3.3 and 3.4 against Rails 8.0 and 8.1, four combinations, with fail-fast: false so one failure does not hide the others. The release job now depends on it.

Pinning works through RAILS_VERSION in the Gemfile, which constrains the six Rails libraries the gemspec depends on. No new development dependency: Appraisal would have done this too, but an environment variable and six gem lines are less machinery for the same result. It also works locally:

RAILS_VERSION=8.0 bundle install && RAILS_VERSION=8.0 bundle exec rake test

I ran exactly that before opening this: Rails 8.0 passes, 301 runs, 0 failures. So this PR does not fix a latent incompatibility, it converts an untested claim into a verified one.

On Ruby 4.0

Not in the matrix. I have been developing this gem on Ruby 4.0.5 locally while CI ran 3.3, so it demonstrably works, but the gemspec does not advertise it and adding it would widen the support claim rather than verify the existing one. Recorded in the roadmap as the remaining gap.

Roadmap

Records compatibility CI under "Implemented and tested" and reduces milestone 7 to the security-scanning half, noting Ruby 4.0 is still absent, per the requirement added in #15.

Compatibility

No library change. RAILS_VERSION is unset in normal use, so bundle install behaves exactly as before.

Validation

bundle exec rake                                    # 301 runs, 0 failures
RAILS_VERSION=8.0 bundle exec rake test             # 301 runs, 0 failures

Standard Ruby, RuboCop, RBS, Steep, and Brakeman clean.

[greptile-apps]

Greptile Summary

The PR adds a Rails/Ruby compatibility matrix, makes releases depend on it, and pins Rails families through RAILS_VERSION. It also prevents expired synchronous SQLite deadlines from producing a negative condition-variable wait and adds regression coverage.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
.github/workflows/ci.yml	Adds the four-combination compatibility matrix and gates releases on its success.
Gemfile	Applies an optional compatible-version constraint to the six Rails libraries when RAILS_VERSION is set.
lib/solid_objects/database_adapters/sqlite.rb	Avoids passing a non-positive interval to the condition-variable wait after a synchronous deadline expires.
test/integration/synchronous_invocation_test.rb	Adds regression coverage for an already-expired retry deadline.
CHANGELOG.md	Consolidates the compatibility and SQLite retry changes into the existing Unreleased section.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  Matrix["Ruby 3.3 / 3.4 × Rails 8.0 / 8.1"] --> Pin["Set RAILS_VERSION"]
  Pin --> Bundle["Resolve pinned Rails libraries"]
  Bundle --> Tests["Run test suite"]
  Tests --> Release["Permit release job"]

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_{Reviews (2): Last reviewed commit: "docs: merge the unreleased changelog sec..." | Re-trigger Greptile}

[greptile-apps]

Duplicate Unreleased sections

The new compatibility entry creates a second consecutive Unreleased section, splitting current changes between identical headings and making release-note generation ambiguous.

Suggested change

	- Run compatibility CI across the span the gemspec advertises: Ruby 3.3 and 3.4
	against Rails 8.0 and 8.1. The suite previously ran on one combination, so
	`>= 8.0` was a claim rather than a tested guarantee. Set `RAILS_VERSION` to
	pin a Rails line locally.
	## Unreleased
	- Run compatibility CI across the span the gemspec advertises: Ruby 3.3 and 3.4
	against Rails 8.0 and 8.1. The suite previously ran on one combination, so
	`>= 8.0` was a claim rather than a tested guarantee. Set `RAILS_VERSION` to
	pin a Rails line locally.

Prompt To Fix With AI

This is a comment left during a code review.
Path: CHANGELOG.md
Line: 5-10

Comment:
**Duplicate Unreleased sections**

The new compatibility entry creates a second consecutive `Unreleased` section, splitting current changes between identical headings and making release-note generation ambiguous.

```suggestion
- Run compatibility CI across the span the gemspec advertises: Ruby 3.3 and 3.4
  against Rails 8.0 and 8.1. The suite previously ran on one combination, so
  `>= 8.0` was a claim rather than a tested guarantee. Set `RAILS_VERSION` to
  pin a Rails line locally.
```

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

[cardmagic]

Right, main already carried an unreleased section from the wake-up adapter and I added a second. Merged into one so release notes stay unambiguous.

[cardmagic]

@greptileai review