GHES mode emits artifact actions unsupported by GHES

[fchareyr]

Description

gh aw v0.86.2 cannot produce runnable agentic workflow lockfiles for GitHub Enterprise Server instances that require artifact action v3. Both repository configuration (.github/workflows/aw.json with "ghes": true) and gh aw compile --ghes still emit actions/upload-artifact@v7.0.1 and actions/download-artifact@v8.0.1.

Those actions fail on GHES with GHESNotSupportedError before the agent runs.

Steps to Reproduce

1. Use a GHES repository whose Actions artifact backend does not support @actions/artifact v2.0.0+.
2. Set "ghes": true in .github/workflows/aw.json.
3. Compile an agentic workflow with gh aw compile --ghes --validate.
4. Dispatch the generated workflow.

Expected Behavior

GHES compatibility mode should emit artifact action versions supported by the target GHES instance, or clearly reject unsupported GHES versions/configurations before producing a runnable-looking lockfile.

Actual Behavior

The compiler emits v7/v8 artifact actions. The generated workflow reaches activation and fails at Upload activation artifact with:

GHESNotSupportedError: @actions/artifact v2.0.0+, upload-artifact@v4+ and download-artifact@v4+ are not currently supported on GHES.

Environment

• gh-aw: v0.86.2
• GHES: 3.21.3
• Runner: self-hosted Linux ARC runner
• Engine: Copilot

Investigation

• gh aw compile emits artifact actions unsupported on GHES #29551 originally reported this exact incompatibility.
• feat: add GHES-compatible artifact action versions via feature flag #31664 added ghes-artifact-compat, which emitted v3 artifact actions and closed gh aw compile emits artifact actions unsupported on GHES #29551.
• Stop compiler from emitting deprecated artifact v3 pins in GHES mode #43298 deliberately removed that behavior because v3 artifact backend APIs were retired on GitHub.com. It also updated the compiler to assert that GHES mode must not emit v3 pins.
• The current documentation correctly describes the resulting behavior (“latest non-v3 pins”), but it simultaneously warns that v4+ actions fail on GHES instances such as this one. There is therefore no released configuration that produces runnable artifact actions for affected GHES versions.

Requested Resolution

Please restore a supported, explicit compatibility path for GHES instances requiring v3 artifact actions, or add target-version detection and fail compilation with a clear actionable error. The documentation should state the supported GHES version range and the absence of a compatible emitted lockfile where applicable.

Additional Context

Investigation and redaction of this report were AI-assisted.

[fchareyr]

Related to #39889, the open GHES compatibility umbrella. #39889 already tracks #29551; this report adds the confirmed #31664 → #43298 regression sequence and an observed GHES 3.21.3 runtime failure.