[CI Broken] Multiple CI test failures - Julia pre-release and downgrade compatibility issues

CI Broken - Multiple Test Failures Detected

Summary

Automated CI health check detected multiple test failures in the master branch:

1. Tests (pre) / Tests - Julia pre-release version (1.13.0-alpha2) fails due to JET package incompatibility
2. Downgrade test - Julia 1.10 with minimum dependencies fails due to RecursiveArrayTools version constraint

CI Run Details

• Health Check PR: #54
• Failed Workflows:
  • Tests workflow: https://github.com/SciML/GeometricIntegratorsDiffEq.jl/actions/runs/20796633119
  • Downgrade workflow: https://github.com/SciML/GeometricIntegratorsDiffEq.jl/actions/runs/20796632963

Failure 1: Julia Pre-release (1.13.0-alpha2) - JET Package Incompatibility

Error Message:

ERROR: LoadError: Unsatisfiable requirements detected for package JET [c3a54625]:
 JET [c3a54625] log:
 ├─possible versions are: 0.0.1 - 0.11.3 or uninstalled
 ├─restricted to versions 0.9 - 0.11 by project [b4209d20], leaving only versions: 0.9.0 - 0.11.3
 │ └─project [b4209d20] log:
 │   ├─possible versions are: 0.0.0 or uninstalled
 │   └─project [b4209d20] is fixed to version 0.0.0
 └─restricted by julia compatibility requirements to versions: uninstalled — no versions left

Root Cause:

The JET package (versions 0.9-0.11) is not compatible with Julia 1.13.0-alpha2. The julia compatibility requirements for JET restrict it to "uninstalled" status on Julia pre-release, making the dependency unsatisfiable.

Job Details:

• Job: Tests (pre) / Tests
• Job ID: 59731738236
• Julia Version: 1.13.0-alpha2
• Duration: 39s
• Step Failed: "Run tests on ubuntu-latest with Julia vpre"

Failure 2: Downgrade Test - RecursiveArrayTools Version Constraint

Error Message:

ERROR: LoadError: Unsatisfiable requirements detected for package RecursiveArrayTools [731186ca]:
 RecursiveArrayTools [731186ca] log:
 ├─possible versions are: 0.16.0-3.42.1 or uninstalled
 └─restricted to versions 2.39.0 by an explicit requirement — no versions left

Root Cause:

The downgrade compatibility test explicitly requires RecursiveArrayTools version 2.39.0, but this specific version does not exist in the available version range (0.16.0-3.42.1). This appears to be a downgrade compat specification issue.

Job Details:

• Job: test (alldeps, 1.10)
• Job ID: 59731737494
• Julia Version: 1.10.10
• Workflow: Downgrade
• Duration: 1m1s
• Step Failed: "Run julia-actions/julia-runtest@v1"

Suggested Fixes

For Failure 1 (Julia Pre-release):

1. Option A: Update JET package compatibility constraints in Project.toml to support Julia 1.13
2. Option B: Wait for JET to release a version compatible with Julia 1.13
3. Option C: Make the pre-release test optional (allow failure) until upstream compatibility is resolved
4. Option D: Temporarily remove JET tests from the pre-release CI until JET adds Julia 1.13 support

For Failure 2 (Downgrade Test):

1. Check the downgrade compat specifications - the version 2.39.0 for RecursiveArrayTools doesn't exist
2. Update the compat bounds to use an actual existing version (likely should be 2.39.x where x is a valid version)
3. Verify all downgrade compat entries in Project.toml reference valid package versions

Impact

• Master branch CI is currently failing
• PRs cannot merge with green CI status
• Pre-release Julia testing is blocked
• Minimum dependency testing is blocked

Next Steps

1. Investigate and fix the RecursiveArrayTools downgrade compat entry (this is likely easier to fix)
2. Decide on approach for JET compatibility with Julia 1.13 pre-release
3. Consider whether to make pre-release tests optional to avoid blocking CI on upstream pre-release incompatibilities

@ChrisRackauckas

---

This issue was automatically created by CI health check monitoring on 2026-01-07

Inspect Project.toml and the Tests and Downgrade workflows first, then reproduce the two failures from the linked CI runs. Verify the RecursiveArrayTools downgrade entry against available versions and determine how the Julia pre-release JET incompatibility should be handled. Done means the affected CI jobs pass or the pre-release limitation is explicitly handled.