fix: preserve PipelineRun-owned TaskRuns during history pruning

[yuzichen12123]

Summary

History-limit cleanup can delete completed TaskRuns that belong to a still-running PipelineRun. The PipelineRun controller then treats those tasks as unscheduled and recreates them, causing completed pipeline work to run again.

This change excludes PipelineRun-owned resources from the history-limiter candidate set. It recognizes both ownership signals used by Tekton:

• the tekton.dev/pipelineRun label;
• a PipelineRun ownerReference.

The ownerReference check protects resources that do not carry the label.

Fixes #381

Testing

• go test ./...

The regression test verifies that history pruning removes eligible standalone resources while preserving PipelineRun children identified by either ownership mechanism.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 50.56%. Comparing base (717a04d) to head (d664de5).
⚠️ Report is 19 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #424      +/-   ##
==========================================
+ Coverage   50.40%   50.56%   +0.16%     
==========================================
  Files          19       19              
  Lines        2113     2120       +7     
==========================================
+ Hits         1065     1072       +7     
  Misses        916      916              
  Partials      132      132              

Flag	Coverage Δ
unit-tests	50.56% <ø> (+0.16%)	⬆️

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[infernus01]

It's an LGTM from my side

[infernus01]

Thanks for the fix @yuzichen12123!

One nit: Could we have used this fucntion instead of creating another one with similar logic ?

[yuzichen12123]

Thanks for the suggestion. isStandaloneTaskRun is defined in pkg/reconciler/taskrun, while the history limiter is implemented in pkg/config. The taskrun package already imports config, so having config call back into taskrun would create an import cycle.

The existing helper is also unexported and TaskRun-specific, whereas the history limiter is shared by TaskRuns and PipelineRuns. The current implementation therefore keeps the ownership check in pkg/config while preserving the same label and ownerReference logic. We can extract a shared helper into a common package in a follow-up refactor if needed.

[infernus01]

Yeah lets put shared function in pkg/config/helper.go, that's a small change I believe and keeps the ownership logic in one place. Thoughts on just including it here vs follow-up? either way works, but since we're already touching this area, so we can do it in this PR itself.

[yuzichen12123]

Thanks @infernus01, agreed. I've included this refactor in the PR in c4dac9f.

The ownership check now lives in pkg/config/helper.go as IsPipelineRunOwned, shared by the history limiter and the standalone TaskRun check. isStandaloneTaskRun delegates to the shared helper, keeping both the label and ownerReference checks in one place without introducing an import cycle.

I've added table-driven coverage for the ownership signals, empty labels, and unrelated or mixed ownerReferences, and kept the original history-pruning regression test. make test-unit (including the race detector), go vet ./..., and lint checks pass locally. The new PR CI is queued.

[infernus01]

/kind bug

[tekton-robot]

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