FE: Use unique filenames for saved messages

[HurSungYun]

• Breaking change? (if so, please describe the impact and migration path for existing application instances)

What changes did you make? (Give an overview)

AS-IS

Currently, when users click the "Save as a file" button in the Messages tab, every file has the same name. As a result, users cannot distinguish between multiple saved messages.

TO-BE

The filename should use the following format:

${sanitizedTopicName}-${partition}-${offset}.json

This ensures that each saved message has a unique filename.

2026-06-25.11.31.37.mov

Is there anything you'd like reviewers to focus on?

None

How Has This Been Tested? (put an "x" (case-sensitive!) next to an item)

• No need to
• Manually (please, describe, if necessary)
• Unit checks
• Integration checks
• Covered by existing automation

Checklist (put an "x" (case-sensitive!) next to all the items, otherwise the build will fail)

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (e.g. ENVIRONMENT VARIABLES)
• My changes generate no new warnings (e.g. Sonar is happy)
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged

Check out Contributing and Code of Conduct

A picture of a cute animal (not mandatory but encouraged)

Summary by CodeRabbit

• New Features
  • “Save as a file” now downloads each message with a unique, readable filename based on the topic name, partition, and offset.
• Bug Fixes
  • Replaced the generic filename for message exports, making saved files easier to identify and avoid overwriting.

[kapybro]

AI Summary

The issue describes a problem where saved message files in the Messages tab have identical filenames, making it difficult for users to distinguish between multiple saved messages. The proposed solution is to use a unique filename format combining the sanitized topic name, partition, and offset, ensuring each file is distinct. Manual testing was performed to validate the solution.

[coderabbitai]

📝 Walkthrough

Walkthrough

The message download filename now includes a sanitized topic name plus partition and offset instead of a fixed filename.

Changes

Message download filename

Layer / File(s)	Summary
Per-message filename frontend/src/components/Topics/Topic/Messages/Message.tsx	useDataSaver now receives a filename derived from topicName with invalid characters replaced by _, together with partition and offset.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Poem

I nibble names to make them neat,
🐰 topic hops to filename street.
Partition, offset—now in tow,
A tidy save for each message flow.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
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.
Title check	✅ Passed	The title clearly matches the main change: saved message downloads now use unique filenames.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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