KVStore: neglect TransferLeader for nextgen compatibility

[CalvinNeo]

What problem does this PR solve?

Issue Number: close #10734

Problem Summary:

neglect TransferLeader for next-gen compatibility. Also downgrade logging level about transfer leader from error to info

• Update logging about transfer leader tidb-engine-ext#451
• https://github.com/tidbcloud/cloud-storage-engine/pull/4720

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

Summary by CodeRabbit

• Bug Fixes

  • Improved handling of admin commands (including TransferLeader and peer update flows) to avoid unnecessary operations during leadership and peer transitions.

• Tests

  • Added test coverage validating TransferLeader routing and adjusted test flow to reflect the new handling.

[pantheon-ai]

❌ Failed to Create Project

We encountered an error while creating your project. Please try again or contact support if the issue persists.

[coderabbitai]

📝 Walkthrough

Walkthrough

Routes the TransferLeader admin command into the existing no-op admin command path and updates unit tests to assert the no-op behavior; adjusts the subsequent CompactLog test index. Adds a comment clarifying proxy rewrite vs next-gen proxy dispatch behavior.

Changes

Cohort / File(s)	Summary
Admin Command Handling dbms/src/Storages/KVStore/MultiRaft/RaftCommandsKVS.cpp	Added a TransferLeader case to route the command to handleUselessAdminRaftCmd (treated as no-op) and included an explanatory comment about tiflash-proxy rewrites vs next-gen proxy dispatch.
Test Coverage dbms/src/Storages/KVStore/tests/gtest_new_kvstore.cpp	Added a TransferLeader path to KVStoreAdminCommands test (expects EngineStoreApplyRes::None) and incremented the index used for the subsequent CompactLog test from 26 to 27.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested labels

lgtm

Suggested reviewers

• JinheLin
• JaySon-Huang

Poem

🐰 I hopped through branches, light and fleet,
Found a leader switch and made it neat.
Routed gently to a harmless song,
Tests now nod and carry on. ✨

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (1 warning, 1 inconclusive)

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.
Description check	❓ Inconclusive	The PR description includes the issue number, problem summary, and mentions related PRs, but lacks a detailed commit message explaining the implementation changes.	Add a detailed commit message in the designated section explaining what was changed and how it solves the problem (e.g., routing TransferLeader through handleUselessAdminRaftCmd, logging level downgrade).

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'KVStore: neglect TransferLeader for nextgen compatibility' directly describes the main change: handling the unsupported TransferLeader admin command to prevent crashes.
Linked Issues check	✅ Passed	The code changes route TransferLeader commands through handleUselessAdminRaftCmd, which prevents the fatal exception by treating them as unsupported but non-fatal, directly addressing issue #10734.
Out of Scope Changes check	✅ Passed	All changes are directly related to handling TransferLeader commands; the test updates align with the implementation changes and no unrelated modifications are present.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@dbms/src/Storages/KVStore/MultiRaft/RaftCommandsKVS.cpp`:
- Around line 186-189: Fix the typos in the comment above the switch cases for
raft_cmdpb::AdminCmdType::TransferLeader and
raft_cmdpb::AdminCmdType::UpdateGcPeer: change "Initialy" to "Initially" and
"rewrited" to "rewritten" so the comment reads correctly while leaving the
surrounding logic and case labels untouched.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 1b740495-4d2d-4ad1-803a-1a420fc4b188

📥 Commits

Reviewing files that changed from the base of the PR and between f27e905 and 7e1aa7d.

📒 Files selected for processing (1)

• dbms/src/Storages/KVStore/MultiRaft/RaftCommandsKVS.cpp

[JaySon-Huang]

Wait for the proxy logging downgrade pr to be merged. In order to reduce the efforts to do when cherry-pick

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JaySon-Huang, JinheLin

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

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Details

Needs approval from an approver in each of these files:

• OWNERS [JaySon-Huang,JinheLin]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-03-10 08:40:14.43915136 +0000 UTC m=+339445.951209011: ☑️ agreed by JinheLin.
• 2026-03-10 13:34:19.707026684 +0000 UTC m=+357091.219084345: ☑️ agreed by JaySon-Huang.

[JaySon-Huang]

/cherry-pick release-nextgen-20251011

[ti-chi-bot]

@JaySon-Huang: failed to apply #10737 on top of branch "release-nextgen-20251011":

[failed to git add conflicting files: exit status 128, failed to git commit: exit status 128]

Details

In response to this:

/cherry-pick release-nextgen-20251011

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