[bmuddha]

What changed

Materializing an account, deleting it, and materializing the same image before the blockhash changes can produce the same signed transaction. Signature deduplication then rejects necessary work as AlreadyProcessed.

Append a random u64 nonce as a signed MagicRoot no-op to distinguish separate private account mutations within one blockhash lifetime.

Related to magicblock-validator#1813. This covers Engine's account mutations; the scheduler's base-chain transaction builder is unchanged.

Impact

Each private mutation gains one built-in instruction. The nonce variant is appended to the MagicRoot enum, leaving existing instruction discriminants unchanged. Validator and verifier must both consume the updated Engine to replay these transactions.

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ℹ️ Recent review info

⚙️ Run configuration

• Source mode: Auto
• Repository: magicblock-labs/magicblock-engine
• Branch: fix/private-mutation-nonce
• File: .coderabbit.yaml
• Commit: 3f52268
• Layers: Repository YAML
• Review profile: ASSERTIVE
• Plan: Advanced
• Run ID: e67aa1cd-860a-4c56-a51b-1bb917ed3b60

📥 Commits

Reviewing files that changed from the base of the PR and between 1bcb0bd and 3f52268.

⛔ Files ignored due to path filters: 1

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

📒 Files selected for processing: 5

• engine/Cargo.toml
• engine/src/accessor.rs
• engine/src/transaction.rs
• programs/magic-root-interface/src/lib.rs
• programs/magic-root-program/src/processor.rs

Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review.

📝 Walkthrough

The magic-root interface adds a nonce instruction, and the processor handles it as a successful no-op after target-account lookup. The engine appends an authority-composed random nonce to private transactions and checks instruction-trace and account-lock limits. Accessor execution now passes owned instruction vectors.

Priority: ➖ Normal

Change: Bug fix

Merge Risk: 🔵 Low · up to 3f522

At the exact trace-capacity boundary, some private transactions with nested actions may now fail; this is a narrow follow-up risk.

Pre-merge checks: 5

Check name	Status	Explanation
Title check		The title clearly describes the main change: distinguishing repeated private account mutations.
Description check		The description directly explains the duplicate-signature problem, the nonce-based fix, its impact, and related issue.
Docstring Coverage		Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 4 files. (1 skipped: 1 …
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 4 files. (1 skipped: 1 unsupported.)

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