feat: ActionArgs::default() to abstract escrow_index

[jonasXchen]

Summary by CodeRabbit

New Features

• Enhanced action arguments API with builder pattern support for improved configuration workflows. Added convenience methods for initialization and chainable property updates, streamlining the developer experience when working with action parameters.

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[coderabbitai]

Walkthrough

Added an inherent impl block for ActionArgs with constructor, getter methods, and builder-style method. Includes default(data: Vec<u8>) constructor initializing escrow_index to 255, getters for escrow_index() and data(), and with_escrow_index() builder method for fluent API usage.

Changes

Cohort / File(s)	Change Summary
ActionArgs API Enhancement magicblock-magic-program-api/src/args.rs	Added inherent impl block with: (1) default(data: Vec<u8>) -> Self constructor initializing escrow_index to 255; (2) escrow_index(&self) -> u8 getter; (3) data(&self) -> &Vec<u8> getter; (4) with_escrow_index(mut self, index: u8) -> Self builder method.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

• Verify getter implementations return correct field references
• Confirm default() constructor properly initializes both escrow_index (255) and data fields
• Check builder method signature and self-consumption pattern are idiomatic

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title accurately reflects the main change: introducing a default() method for ActionArgs that abstracts the escrow_index initialization.

✨ 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 jonasXchen/magic-action-args

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[coderabbitai]

Actionable comments posted: 1

📜 Review details

Configuration used: CodeRabbit UI

Review profile: ASSERTIVE

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between b5823d8 and 5f2a30b.

📒 Files selected for processing (1)

• magicblock-magic-program-api/src/args.rs (1 hunks)

⏰ 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). (3)

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🔇 Additional comments (3)

magicblock-magic-program-api/src/args.rs (3)

22-24: Getter is redundant but acceptable for future-proofing.

Since escrow_index is a public field (line 11), this getter is technically redundant. However, it may be useful if you plan to make the field private in the future or add validation logic.

---

30-33: Builder pattern implementation is correct and approved.

Verification confirms this is the only builder-style method in the codebase. The implementation correctly consumes self, updates the field, and returns self for method chaining.

---

16-21: Rename default to new to avoid confusion with the Default trait.

The method name default misleadingly suggests the standard Default trait, which has a different signature (no parameters). Since this is a custom constructor taking data as a parameter, renaming to new aligns with Rust conventions.

Additionally, document the magic number 255 for escrow_index. Extract it to a named constant or add a doc comment explaining its semantic meaning (e.g., whether it represents "no escrow" or "unset").

+    /// Creates a new ActionArgs with the given data and a default escrow_index of 255 (no escrow selected).
-    pub fn default(data: Vec<u8>) -> Self {
+    pub fn new(data: Vec<u8>) -> Self {
         Self {
             escrow_index: 255,
             data,
         }
     }

Since no existing call sites were found, this rename poses no integration risk.

[coderabbitai]

🛠️ Refactor suggestion | 🟠 Major

Return &[u8] instead of &Vec<u8> for idiomatic Rust.

Returning &Vec<u8> is considered an anti-pattern in Rust because it exposes the implementation detail and limits flexibility. Instead, return &[u8], which works with vectors, arrays, and slices. Callers can still obtain &Vec<u8> via deref coercion if needed.

Apply this diff:

-    pub fn data(&self) -> &Vec<u8> {
-        &self.data
+    pub fn data(&self) -> &[u8] {
+        &self.data
     }

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

	pub fn data(&self) -> &Vec<u8> {
	&self.data
	}
	pub fn data(&self) -> &[u8] {
	&self.data
	}

🤖 Prompt for AI Agents

In magicblock-magic-program-api/src/args.rs around lines 26 to 28, the accessor
currently returns &Vec<u8> which leaks the implementation; change the method
signature to return a slice (&[u8]) instead and return a slice of the vector
(e.g., via as_slice() or a full-range slice) so callers get a &[u8] while the
internal field remains Vec<u8>.