[R-4] Standardized fix

[Kukoomomo]

Summary by CodeRabbit

• Chores
  • Updated internal documentation and improved code consistency in fee calculation and token balance management modules. These internal refinements maintain code quality and clarity without affecting user-facing functionality.

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[coderabbitai]

Walkthrough

This pull request addresses minor documentation and naming consistency issues across three files. The changes include updating an inline comment in receipt type definitions, correcting variable naming inconsistencies in fee rate calculations, and refining a comment in token balance state updates.

Changes

Cohort / File(s)	Change Summary
Documentation updates core/types/receipt.go, rollup/fees/token_transfer.go	Updated inline comments: v7StoredReceiptRLP comment simplified from "AltFee feature was added (2024-11)" to "AltFee feature was added"; changeAltTokenBalanceByState comment refined from "Calculate the storage slot for the user's balance" to "Change user balance"
Variable naming fixes rollup/fees/rate.go	Corrected variable names tokenSacle and tokenScale to scale in EthToAlt and AltToETH functions to align with TokenRate return value signature

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

• Minimal scope: three files with isolated, non-functional changes
• Two files contain only comment updates with no logic impact
• One file has straightforward variable name corrections that are self-evident and low-risk

Possibly related PRs

• Fix receipt rlp #247: Modifies the same v7StoredReceiptRLP comment and AltFee field documentation in receipt encoding types
• Implement alt token fee #205: Updates the same rollup/fees/rate.go functions (EthToAlt/AltToETH) that introduced the token fee logic
• Fix err return when token info invalid #261: Also addresses token scale variable usage in rollup/fees/rate.go EthToAlt/AltToETH functions

Suggested reviewers

• curryxbo
• tomatoishealthy

Poem

🐰 A comment here, a variable there,
Tiny tweaks with careful care,
No logic bent, just names refined,
The cleanest code we'll ever find! ✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.
Title check	❓ Inconclusive	The title '[R-4] Standardized fix' is vague and does not clearly convey the specific changes made in the pull request.	Replace with a more descriptive title that specifically mentions the changes, such as 'Fix variable naming inconsistencies and update comments' or 'Standardize variable names in fee calculation and receipt types'.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

✨ Finishing touches

• 📝 Generate docstrings

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• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix_code_name

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📜 Recent review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 9217e7b and 25dbd6d.

📒 Files selected for processing (3)

• core/types/receipt.go (1 hunks)
• rollup/fees/rate.go (1 hunks)
• rollup/fees/token_transfer.go (1 hunks)

🧰 Additional context used

🧠 Learnings (1)

📚 Learning: 2025-11-10T06:56:24.937Z

Learnt from: Kukoomomo
Repo: morph-l2/go-ethereum PR: 205
File: core/token_gas.go:140-155
Timestamp: 2025-11-10T06:56:24.937Z
Learning: In the ERC20 fee implementation (core/token_gas.go), ERC20 transfer and balance check calls use math.MaxUint64 gas limit. This is intentional given that fee tokens are restricted to an allowlist (via IsTokenActive checks and AllowListSlot/AllowListEnabledSlot in rollup/rcfg/config.go), so only vetted contracts can be invoked. The team has chosen this approach understanding the tradeoffs versus adding fixed gas stipends.

Applied to files:

• rollup/fees/token_transfer.go

🧬 Code graph analysis (1)

rollup/fees/rate.go (1)

core/types/token_fee.go (2)

• EthToAlt (52-66)
• AltToEth (69-83)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)

• GitHub Check: Analyze (go)

🔇 Additional comments (4)

core/types/receipt.go (1)

127-128: LGTM!

Removing the date reference "(2024-11)" from the comment is a reasonable cleanup. The essential context about the AltFee feature introduction is preserved, and omitting the specific date avoids potential staleness.

rollup/fees/rate.go (2)

30-36: LGTM!

The variable rename from tokenSacle (typo) to scale improves readability and aligns with the TokenRate return signature (rate, scale, err).

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38-44: LGTM!

Same naming fix applied consistently to AltToETH.

rollup/fees/token_transfer.go (1)

62-63: LGTM!

The updated comment "Change user balance" accurately describes the SetState operation on line 63. The previous comment was misleading since the storage slot calculation actually occurs earlier on line 41 via GetAltTokenBalanceFromSlot.

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