Adds §5 Programming choice flow — a decision tree that runs before writing
any new code. Covers:
- Admissibility / gating / routing logic → Lean only
- Receipt minting / top-level JSON emission → AVMIsa.Emit only (sole boundary)
- Alignment classification → Lean (RRC.Emit or new Semantics.RRC.*)
- Raw input features → Python shim acceptable with strict constraints
(no admissibility logic, regenerable, TODO(lean-port) if portable)
- Float in compute paths → STOP, use Q16_16
- Promotion advancement in shim space → STOP, always not_promoted until
a Lean gate passes
- Pure I/O → Python shim fine, must route receipt output through AVMIsa.Emit
Summary rule: Lean owns all decisions. Python owns all I/O.
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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>