Add rate and scale check

[Kukoomomo]

Summary by CodeRabbit

• Bug Fixes
  • Strengthened validation for fee rate configurations to detect and reject missing or zero rate/scale values earlier, improving error reporting (includes token identification in logs) and preventing propagation of invalid parameters.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

Added non-nil and non-zero validation checks in TokenRate (rollup/fees/rate.go) for the returned rate and for info.Scale; on validation failure the code logs an error including token ID and address and returns the existing error early.

Changes

Cohort / File(s)	Summary
Rate validation rollup/fees/rate.go	Added non-nil and non-zero validation for the computed rate and for info.Scale; logs tokenID and token address and returns early on validation failure.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

• Single-file, localized validation additions
• Attention: confirm callers expect original error propagation and that logged tokenID/address are safe to emit

Possibly related PRs

• Fix err return when token info invalid #261: Adjusts TokenRate validation in the same file but removes nil/zero checks and changes error-return behavior.

Suggested reviewers

• tomatoishealthy
• curryxbo

Poem

🐇 I nibble bytes beneath the moonlight,

Checking rates to keep things right,
No nils to hide, no zeros stay—
I guard the hops along the way,
A tiny rabbit, code-bright.

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Add rate and scale check' accurately summarizes the main change: adding validation checks for rate and scale in the TokenRate function.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

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

---

📜 Recent review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 768898d and 64e9dcd.

📒 Files selected for processing (1)

• rollup/fees/rate.go

🧰 Additional context used

🧠 Learnings (1)

📓 Common learnings

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.

⏰ 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)

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Actionable comments posted: 2

📜 Review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between efcdc5e and 768898d.

📒 Files selected for processing (1)

• rollup/fees/rate.go

🧰 Additional context used

🧠 Learnings (1)

📓 Common learnings

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.

⏰ 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)