fix(msfs): interpret AIStore Atime as nanoseconds, not microseconds

[joshuarobinson]

AIStore's ObjAttrs.Atime is an int64 count of nanoseconds since the Unix epoch (per github.com/NVIDIA/aistore/cmn objattrs.go). statFile converted it with time.UnixMicro, treating the value as microseconds, which made every reported modification time ~1000x too large (tens of thousands of years in the future). Use time.Unix(0, props.Atime) to match the rest of the codebase.

https://github.com/NVIDIA/aistore/blob/main/cmn/objattrs.go#L84

Found in merged MR !733.

Checklist

• Development PR
  • .release_notes/.unreleased.md
    • Notable changes to the client (i.e. not related to tooling, CI/CD, etc.) from this PR have been added.
• Release PR
  • CI/CD
    • The default branch pipelines are passing in both GitHub + GitLab (latter for SwiftStack E2E tests).
  • multi-storage-client/pyproject.toml
    • The package version has been bumped.
  • .release_notes/.unreleased.md
    • This file's contents have been moved into a .release_notes/{bumped package version}.md file.

Summary by CodeRabbit

• Bug Fixes
  • Corrected file modification time handling for AIStore-backed files, improving timestamp accuracy and consistency.

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between d72a5de and 2b9a287.

📒 Files selected for processing (1)

• multi-storage-file-system/backend_aistore.go

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📝 Walkthrough

Walkthrough

Changes

AiStore metadata

Layer / File(s)	Summary
File timestamp conversion multi-storage-file-system/backend_aistore.go	statFile converts props.Atime with time.Unix(0, props.Atime) instead of time.UnixMicro(props.Atime).

Estimated code review effort: 1 (Trivial) | ~3 minutes

Suggested reviewers: ankitmaster08

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the change by correcting AIStore Atime handling from microseconds to nanoseconds.
Description check	✅ Passed	The description explains the fix, gives context, and includes the checklist, but it omits the explicit Relates to/Closes task line.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

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• Commit unit tests in branch fix/mr733-aistore-atime-nanoseconds

Warning

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🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain main module or its selected dependencies"

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