Critical: Two incompatible ISA numbering systems

[SuperInstance]

Audit Finding

Severity: Critical
File(s): opcodes.py, isa_unified.py, test_conformance.py

Problem

The repository contains two completely different opcode numbering schemes that are mutually incompatible:

Aspect	opcodes.py (VM executes)	isa_unified.py (spec)
HALT	0x80	0x00
NOP	0x00	0x01
ADD	0x10	0x20
...	completely different offsets	completely different offsets

This means test_conformance.py generates bytecodes using the ISA spec numbers, but the VM interprets them using the opcodes.py numbers. The conformance test can never pass regardless of implementation correctness.

Impact

• Conformance testing is fundamentally broken — false failures or false passes
• Any external tooling that uses isa_unified.py to emit bytecodes will produce garbage when run on the VM
• Blocks all integration across the FLUX ecosystem

Suggested Fix

1. Preferred: Align isa_unified.py opcode values with opcodes.py (the VM is the source of truth for what executes)
2. Alternative: Create a formal mapping/translation layer between the two namespaces, documented in isa_unified.py
3. Update test_conformance.py to use whichever numbering is canonical

Related

• Part of the broader ISA spec vs. VM implementation divergence tracked in flux-spec repo