refactor(node): remove zk-to-mpt migration cleanup leftovers

[curryxbo]

Summary

• remove temporary dual-geth switch path introduced for zk->mpt migration (L2Next config/flags, runtime switch logic, and eth_config migration metadata fetch)
• remove fork-boundary-only batch forcing logic in node batching (forceBatchPointForJadeFork) now that migration is complete
• remove derivation transition-only root validation bypass and clean related migration-specific logging/messages

Test plan

• cd node && go build ./...
• verify touched files have no lint diagnostics in Cursor
• run integration/e2e regression in CI

Made with Cursor

Summary by CodeRabbit

• Chores
  • Removed legacy fork-specific batching and related state handling.
  • Removed multi-endpoint upgrade-switch support and associated CLI flags.
  • Simplified startup to use a single L2 endpoint and reduced client initialization steps.
  • Consolidated retry/client logic to a single consistent RPC path.
  • Clarified and toned down node sync/error messages.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: a13a1340-53bb-42b3-8512-2fb878d992ed

📥 Commits

Reviewing files that changed from the base of the PR and between b03614e and 66ef55a.

📒 Files selected for processing (1)

• node/derivation/derivation.go

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📝 Walkthrough

Walkthrough

Removes Jade/MPT fork upgrade-switch logic and L2Next geth-upgrade support across the node: deletes switch-state, next-client wiring, fork-specific batching override, CLI flags and config fields, and simplifies RetryableClient and related control flow.

Changes

Cohort / File(s)	Summary
Configuration & Flags node/core/config.go, node/derivation/config.go, node/flags/flags.go	Deleted L2Next fields and removed CLI flags L2NextEthAddr / L2NextEngineAddr; removed CLI wiring that constructed L2Next config and any geth-upgrade switch handling.
Retryable client node/types/retryable_client.go	Removed next-client support, switch-time state, and methods (JadeForkTime, EnsureSwitched); changed NewRetryableClient signature to accept only core auth/eth clients and logger; simplified all RPC call sites to use single clients.
Executor & Batching node/core/executor.go, node/core/batch.go	Removed executor fork-state fields and helper forceBatchPointForJadeFork; eliminated conditional batch-point forcing and related logs; simplified DeliverBlock flow (removed EnsureSwitched and post-switch height re-check and reduced critical/error phrasing).
Derivation node/derivation/derivation.go	Removed switchTime/useZktrie state and startup geth-config fetch; removed conditional skip of root/withdrawal validation during upgrade transition so mismatches always trigger state exception and optional challenge.
Build ignores .gitignore	Removed ignore rule for ops/mpt-switch-test (local testing dir).

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~55 minutes

Possibly related PRs

• ZK to MPT #827: Adds MPT/upgrade-switch wiring (L2Next, switchTime, EnsureSwitched, forceBatchPointForMPTFork); directly inverses many removals in this PR.

Suggested reviewers

• r3aker86
• FletcherMan

Poem

🐇 I hopped through code at break of day,
Removed the forks that led astray,
One client now, the paths made clear,
Simpler logs and fewer fear —
My carrots crunch, the repo cheers. 🥕

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main objective of the PR: removing temporary migration-related code (zk-to-mpt migration cleanup leftovers) including L2Next config, fork-boundary batching logic, and transition-only validation.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch cleanup/remove-zk-to-mpt-migration-code

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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 `@node/derivation/derivation.go`:
- Around line 257-262: The log for a failed ChallengeState call omits the
underlying error; update the block around
d.validator.ChallengeState(batchInfo.batchIndex) to include the returned err in
the log (use d.logger.Error/ Errorf/ Errorw as appropriate) so the message
includes the error details and context (e.g., "challenge state failed" plus err
and the batch index), keeping the same control flow and return behavior; locate
symbols d.validator, ChallengeState, ChallengeEnable, d.logger.Error and
batchInfo.batchIndex to make the change.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 62d16add-ccac-4bcf-8a1b-cd392ab5b452

📥 Commits

Reviewing files that changed from the base of the PR and between 0165591 and b03614e.

📒 Files selected for processing (8)

• .gitignore
• node/core/batch.go
• node/core/config.go
• node/core/executor.go
• node/derivation/config.go
• node/derivation/derivation.go
• node/flags/flags.go
• node/types/retryable_client.go

💤 Files with no reviewable changes (4)

• node/core/batch.go
• node/core/config.go
• node/derivation/config.go
• node/flags/flags.go