interop-offset-audit

name: interop-offset-audit description: "Use when checking nanoFramework InternalCall bindings, managed/native interop method order, method_lookup index drift, signature mismatches, checksum/version consistency, or after refactors in Cubley.Interop and native interop tables. Keywords: interop offset, method_lookup, InternalCall, BYREF mismatch, native binding audit, W5500 interop map."

Interop Offset Audit

Purpose

Validate that managed InternalCall declarations and native method tables are still aligned after refactors.

This skill is optimized for this repository's Cubley interop surfaces.

Primary Targets

• software/nanoFramework/Cubley.Interop/CubleyInteropNative.cs
• software/nanoFramework/Cubley.Interop/Properties/AssemblyInfo.cs
• software/nanoFramework/nf-native/cubley_interop.cpp
• software/nanoFramework/nf-native/w5500_interop.cpp

When To Use

• After renaming or adding interop methods.
• After changing out parameters, especially BYREF signatures.
• When managed code appears to run but native methods are never hit.
• When mailbox status does not progress as expected.

Workflow

1. Read managed declarations in CubleyInteropNative.cs in source order.
2. Read native method_lookup order in cubley_interop.cpp.
3. Compare one by one:
   • method name intent
   • parameter shape (plain vs BYREF)
   • return shape
4. Confirm the native assembly identity and version/checksum alignment:
   • AssemblyNativeVersion in managed assembly metadata
   • native table export name/checksum in cubley_interop.cpp
5. Verify native function symbols exist with the expected names in the build ELF when available.
6. Produce a concise report:
   • PASS if all slots align
   • FAIL with exact slot index and symbol pair

Output Format

• Summary: PASS or FAIL
• Findings list:
  • slot index
  • managed declaration
  • native handler
  • mismatch category (order, signature, missing symbol, assembly identity)
• Recommended fix steps (minimal, specific)

Guardrails

• Do not reorder methods unless mismatch is proven.
• Prefer the smallest change that restores alignment.
• Do not change public managed APIs unless required.
• If build artifacts are missing, still perform static mapping audit and clearly mark runtime checks as pending.