Stacked on #4020, not independently mergeable.
Nothing on the same-repo PR path consumes either half of what
`build-talos` produces. `image-talos` pushes
`${REGISTRY}/talos:pr-N-sha`, which no chart in the tree references and
which is not even version-tagged here (`PUBLISH_VERSIONED` and
`PUBLISH_FLOATING` are both 0). `image-matchbox` stamps
`packages/extra/bootbox/images/matchbox.tag`, and that one line is the
whole content of `pr-patch-fragment-talos` - checked against the
artifact from a real run - but bootbox is opt-in and the E2E platform
Package does not enable it, so no run pulls the image. Unstamped tag
leaves installer artifact pointing at released matchbox, which is a
valid ref nothing on this path resolves.
So the job ran a privileged siderolabs imager build on every PR for two
artifacts with no reader. Now it runs when the PR touched
`packages/core/talos`, and `finalize` accepts a skipped result as well
as a successful one. Without that second half skipping it would block
finalize, and therefore e2e, on nearly every PR.
Forks keep the unconditional build, and the reason is not about talos.
`e2e-fork.yaml` publish job requires at least one OCI archive to exist,
an invariant that holds today only because this job always ran, so a
fork PR touching nothing under `packages/` would arrive with an empty
export and fail a legitimate run. Teaching that guard what `plan`
expected to build is work in the fork allowlist path and belongs in its
own change.
Saving is about 1.5-2 min of critical path. Main point is removing a
privileged image build that nobody reads from every pull request.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **CI Improvements**
- Pull request validation now runs Talos builds only when relevant
changes require them, while retaining full validation for fork-based
contributions.
- Finalization correctly handles skipped Talos builds and preserves
generated boot artifacts when builds succeed.
- Changed-file detection now accounts for renames, deletions, and shared
build inputs.
- **Documentation**
- Updated testing and build guidance to reflect the current validation
behavior.
- **Tests**
- Added comprehensive coverage for build classification, workflow
outputs, skipped jobs, and artifact handling.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
myasnikovdaniil
a1b32f2e5a