document io byte layout above flowInit assembly

[thedavidmeister]

Summary

The assembly block in flowInit reading flowInputs / flowOutputs from the deployer-returned io bytes had no comment explaining the layout — why add(io, 0x20) skips the bytes-length word and why bytes 0 and 1 are the relevant offsets.

Added a per-block comment naming the deployer's per-source (inputs, outputs) byte-pair convention and noting that the single-source flow entrypoint (FLOW_ENTRYPOINT == 0) pins source 0.

Closes #350.

Test plan

• build clean (comment-only)

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation
  • Improved internal code clarity with enhanced comments and explanations.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 2aacaef7-0c2d-4c63-89ef-2818d9e22b56

📥 Commits

Reviewing files that changed from the base of the PR and between ceaea3c and 585851e.

📒 Files selected for processing (1)

• src/concrete/Flow.sol

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Walkthrough

Inline comments were added to the flowInit assembly block in src/concrete/Flow.sol to document the byte layout of the io parameter returned from expression deployment. The comments clarify how mload(add(io, 0x20)) skips the length word and extracts flowInputs and flowOutputs from bytes 0 and 1 respectively.

Changes

Assembly Documentation Clarity

Layer / File(s)	Summary
Assembly Block Comments src/concrete/Flow.sol	Comments added to describe io bytes array structure, explain mload(add(io, 0x20)) memory offset, and document byte positions 0 and 1 for extracting entrypoint source flowInputs and flowOutputs.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly and clearly describes the main change: adding documentation (comments) about the io byte layout above the flowInit assembly block.
Linked Issues check	✅ Passed	The PR fulfills issue #350 by adding a clarifying comment documenting the io byte layout (bytes array with length word, per-source byte pairs, and specific byte positions for flow entrypoint).
Out of Scope Changes check	✅ Passed	All changes are directly related to the stated objective: documenting the io byte layout in comments above the flowInit assembly block per issue #350.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 2026-05-07-issue-350-flowinit-assembly-comment

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