refactor: simplify trait impl with ambassador

[hanabi1224]

Summary of changes

Changes introduced in this pull request:

Reference issue to close (if applicable)

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Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

Outside contributions

• I have read and agree to the CONTRIBUTING document.
• I have read and agree to the AI Policy document. I understand that failure to comply with the guidelines will lead to rejection of the pull request.

Summary by CodeRabbit

• Chores
  • Added new build dependency for improved code maintainability
  • Refactored trait implementations for message handling to reduce boilerplate code
  • Updated internal trait organization across multiple modules

[coderabbitai]

Walkthrough

The pull request adds the ambassador crate as a dependency and refactors trait implementations across message and beacon modules to use ambassador-based delegation instead of manual trait implementations. The message trait hierarchy is restructured, with MessageTrait renamed to MessageReadWrite and message traits marked as delegatable.

Changes

Cohort / File(s)	Summary
Dependency Addition Cargo.toml	Added direct dependency on ambassador version 0.5.
Beacon Abstraction Refactoring src/beacon/drand.rs	Replaced manual BeaconImpl trait implementations with ambassador::Delegate derive and #[delegate(Beacon)] attribute; added #[delegatable_trait] to the Beacon trait; updated test build paths for MockBeacon.
Message Trait Restructuring src/message/mod.rs, src/message/chain_message.rs, src/message/signed_message.rs	Renamed MessageTrait to MessageReadWrite; added #[delegatable_trait] to MessageRead; replaced manual trait implementations with ambassador::Delegate delegation in ChainMessage; updated SignedMessage impl block from MessageTrait to MessageReadWrite; changed function signature for valid_for_block_inclusion to accept &Message instead of &ShimMessage.
Message Handler Type Changes src/chain/store/base_fee.rs	Updated base-fee computation to treat message references as &dyn MessageReadWrite instead of &dyn Message when iterating over message fields.
Import Updates src/rpc/methods/eth.rs, src/rpc/methods/gas.rs, src/state_manager/mod.rs	Updated module imports to include MessageReadWrite trait alongside existing message-related imports for proper method resolution.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• fix: remove unnecessary async_trait usages #6744: Makes overlapping changes to the beacon abstraction in src/beacon/drand.rs, including similar delegation pattern refactoring and trait restructuring.

Suggested labels

dependencies, rust

Suggested reviewers

• LesnyRumcajs
• sudo-shashank

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 63.64% 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 refactoring work: simplifying trait implementations across multiple files using the ambassador crate delegation approach.

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✨ 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 hm/simplify-trait-impl-with-ambassador

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch hm/simplify-trait-impl-with-ambassador

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[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.85%. Comparing base (0fe81e6) to head (c6b21df).
⚠️ Report is 8 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/chain/store/base_fee.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
src/beacon/drand.rs	76.31% <ø> (+0.10%)	⬆️
src/message/chain_message.rs	65.51% <ø> (+13.95%)	⬆️
src/message/mod.rs	90.56% <100.00%> (ø)
src/message/signed_message.rs	82.52% <ø> (ø)
src/rpc/methods/eth.rs	65.55% <ø> (ø)
src/rpc/methods/gas.rs	86.66% <ø> (ø)
src/state_manager/mod.rs	66.46% <ø> (ø)
src/chain/store/base_fee.rs	86.19% <0.00%> (ø)

... and 3 files with indirect coverage changes

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[coderabbitai]

🧹 Nitpick comments (1)

src/beacon/drand.rs (1)

4-4: Scope the dead_code allowance more narrowly.

Line 4 silences the entire module, so genuinely unused production paths in drand.rs will disappear along with any macro-related noise. Please move this to the specific generated item, or drop it once the delegation change compiles cleanly.

🤖 Prompt for AI Agents

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

In `@src/beacon/drand.rs` at line 4, The module-level attribute
#![allow(dead_code)] in drand.rs is too broad; remove that top-level attribute
and either place #[allow(dead_code)] directly on the specific generated item(s)
(the generated function/struct produced by the delegation change) or delete the
attribute entirely once the delegation change compiles cleanly; update the
generated item declaration(s) to carry #[allow(dead_code)] instead of silencing
the whole module.

🤖 Prompt for all review comments with AI agents

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

Nitpick comments:
In `@src/beacon/drand.rs`:
- Line 4: The module-level attribute #![allow(dead_code)] in drand.rs is too
broad; remove that top-level attribute and either place #[allow(dead_code)]
directly on the specific generated item(s) (the generated function/struct
produced by the delegation change) or delete the attribute entirely once the
delegation change compiles cleanly; update the generated item declaration(s) to
carry #[allow(dead_code)] instead of silencing the whole module.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 4ea17874-1580-4a75-93b2-9e94b195b767

📥 Commits

Reviewing files that changed from the base of the PR and between 0fe81e6 and c6b21df.

⛔ Files ignored due to path filters (1)

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (9)

• Cargo.toml
• src/beacon/drand.rs
• src/chain/store/base_fee.rs
• src/message/chain_message.rs
• src/message/mod.rs
• src/message/signed_message.rs
• src/rpc/methods/eth.rs
• src/rpc/methods/gas.rs
• src/state_manager/mod.rs