[quality] cover updater executeBinaryUpdateFlow backup-failure branch (45.5% → 51.0%)

[kubestellar-hive]

Test Improvement

Adds pkg/agent/updater/execute_binary_flow_backup_test.go — one focused
test (TestExecuteBinaryUpdateFlow_BackupFailure) that closes the next
gap after the existing Extract / PostExtractCancellation coverage in
execute_binary_flow_more_test.go.

Branches covered

Three consecutive previously-uncovered branches inside executeBinaryUpdateFlow
(download.go):

1. exec.LookPath("console") err arm — fallback to ./bin/console
2. renameOrCopy(consolePath, backupPath) err arm (source missing)
3. "Failed to back up current binary" failed-status broadcast + recordError path

Approach:

• Reuses existing newRecordingUpdateChecker / serveTarballAndChecksums /
  releaseWith / buildValidTarGz helpers — no test infra churn.
• t.Setenv("PATH", "") forces exec.LookPath to fail; t.Chdir(t.TempDir())
  makes the ./bin/console fallback resolve against a directory that
  provably has no binary. Both auto-restore on teardown.
• Passes the CWE-494 checksum gate + safeTarExtract, so we hit the
  post-extract backup step cleanly.
• Skipped on Windows (fallback path and renameOrCopy semantics differ);
  Linux + macOS runners exercise the branch.

Verified locally

$ go test -run TestExecuteBinaryUpdateFlow_BackupFailure -v ./pkg/agent/updater/
=== RUN   TestExecuteBinaryUpdateFlow_BackupFailure
--- PASS: TestExecuteBinaryUpdateFlow_BackupFailure (0.01s)
ok  github.com/kubestellar/console/pkg/agent/updater

Coverage delta on pkg/agent/updater:

Scope	Before	After
executeBinaryUpdateFlow	45.5%	51.0% (+5.5pp)
pkg/agent/updater total	83.0%	83.6% (+0.6pp)

Since the issue was filed (executeBinaryUpdateFlow @ 13.3%), cumulative
progress across all landed tests is 13.3% → 51.0%.

Not addressed here (intentional)

The remaining ~49% of executeBinaryUpdateFlow sits past the backup step
and each subsequent branch needs its own controlled fixture:

• ChmodIfSupported failure + rollback via backup restore
• renameOrCopy(stagedBinary, consolePath) failure + rollback
• restartBackend() failure + rollback + rollback-restart
• healthCheckFn() false + rollback + rollback-restart
• Full success path through to "done" / currentVersion update

Each of those follows the same pattern (drive to the branch, assert the
broadcast + lastUpdateError, assert no restarting / done), so they
can land as follow-up PRs stacked on this one. Not bundling them here
keeps the diff scoped to a single mechanically-verified branch.

Refs #23160 (issue tracker for the whole flow — remaining post-backup
arms listed above are still open).

---

Filed by quality agent (ACMM L4/L6 — full mode)

— hive: agent=quality backend=copilot model=claude-opus-4.7

[kubestellar-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign clubanderson for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[netlify]

✅ Deploy Preview for kubestellarconsole canceled.

Name	Link
🔨 Latest commit	40031ca
🔍 Latest deploy log	https://app.netlify.com/projects/kubestellarconsole/deploys/6aa63534c392e2000815cc1f

[github-actions]

👋 Hey @kubestellar-hive[bot] — thanks for opening this PR!

🤖 This project is developed exclusively using AI coding assistants.

Please do not attempt to code anything for this project manually.
All contributions should be authored using an AI coding tool such as:

• Claude Code (Opus 4.5 / 4.6) — recommended
• GitHub Copilot
• Cursor
• Other AI coding assistants

This ensures consistency in code style, architecture patterns, test coverage,
and commit quality across the entire codebase.

---

This is an automated message.

[github-actions]

Thank you for your contribution! Your PR has been merged.

Check out what's new:

• KubeStellar Console — Live multi-cluster dashboard
• Marketplace — Community extensions
• Knowledge Base — Troubleshooting and how-tos

Stay connected: Slack #kubestellar-dev | Multi-Cluster Survey

[github-actions]

Post-merge build verification passed ✅

Both Go and frontend builds compiled successfully against merge commit 2e16764d679042c18cd34cc0f645995a1fcc8de5.

[github-actions]

⏹️ Post-Merge Verification: cancelled

Commit: 2e16764d679042c18cd34cc0f645995a1fcc8de5
Specs run: smoke.spec.ts
Report: https://github.com/kubestellar/console/actions/runs/34741301317