refactor: replace []byte(fmt.Sprintf) with fmt.Appendf

[box4wangjing]

Description

I modified the return statement to utilize fmt.Appendf instead of fmt.Sprintf for creating the formatted byte slice.

This change enhances performance by directly appending the formatted string to the byte slice, avoiding the need for intermediate memory allocation created by fmt.Sprintf.

The resulting code is cleaner and more efficient, maintaining the same functionality while improving resource usage.

More info can see golang/go#47579

Related Issue

Motivation and Context

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update (including inline docs)
• Other (please describe):

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Checklist Explanation:

How to Review this PR:

Additional Information:

Summary by CodeRabbit

• Refactor
  • Internal code optimizations applied across multiple modules to improve performance and reduce memory allocations.

[holdex]

Time Submission Status

Member	Status	Time	Action	Last Update
@box4wangjing	❌ Missing	-	⚠️ Submit time	-
MicBun	✅ Submitted	5min	Update time	May 13, 2026, 1:46 PM

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[coderabbitai]

📝 Walkthrough

Walkthrough

This PR replaces fmt.Sprintf() followed by []byte() conversion with fmt.Appendf(nil, ...) across five functions in core implementations and test fixtures. The pattern optimizes string formatting by building bytes directly on the stack instead of allocating heap memory for intermediate strings.

Changes

String Formatting Optimization

Layer / File(s)	Summary
Private Key Marshaling app/key/cmd.go	PrivateKeyInfo.MarshalText() refactored in both Address != "" and Address == "" branches to use fmt.Appendf(nil, ...) instead of []byte(fmt.Sprintf(...)); output remains identical.
Message and Key Formatting app/shared/display/message.go, node/snapshotter/protocol.go	RespResolutionBroadcast.MarshalText() and SnapshotMetadata.Key() updated to build output via fmt.Appendf(nil, ...) for efficient byte sequence construction.
Test Helpers app/shared/display/format_test.go, node/store/store_test.go	Test fixture methods demoFormat.MarshalText and testLargeBlockStore appHash generation switched to fmt.Appendf(nil, ...) pattern.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• MicBun

Poem

🐰 A rabbit hops through sprintf lands,
Where strings once danced in wasteful strands,
Now appendf builds on the stack so neat,
No heap allocs—the refactor's sweet!
Bytes stack-direct, the pattern's clean,
Five functions fixed, a tidy scene! 🎯

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main refactoring change across all modified files: replacing fmt.Sprintf with fmt.Appendf for better performance.
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[MicBun]

nice catch, lgtm

[MicBun]

@holdex pr submit-time 5m