Reference decoders

Tiny, dependency-free implementations of a SPORE Tier-0 node — enough to receive, verify, and display public messages — for machines that don't have a Rust toolchain. They double as cross-language conformance oracles for docs/REBUILD.md: each reproduces the same addresses, IDs, and signature checks as the reference library.

File	What
`spore_t0.py`	Pure-Python T0 node — standard library only; Ed25519 verify is the inlined public-domain reference.
`spore_t0.c`	Pure-C T0 node — zero dependencies; its own SHA-256, SHA-512, and Ed25519 verify (256-bit field arithmetic mod 2²⁵⁵−19). `cc -O2 -o spore_t0 reference/spore_t0.c`.
`spore_t0.sh`	Shell T0 node — parses + content-addresses with `sha256sum`/`base32`, verifies via `openssl` (3.0+). For a box with the usual Unix tools but no Rust/Python.
`vectors.json`	Deterministic test vectors, generated by `cargo run --example gen_vectors`. The source of truth.
`test_t0.py`	Checks `spore_t0.py` against `vectors.json` (address, IDs, a valid signature, a rejected tampered one, armor round-trip).
`test_decoders.sh`	The same conformance for the C and shell decoders (run in CI by `reference.yml`).

All three decoders do the same job — parse an envelope (hex or ~S1.…~ armor), derive the sender's address, recompute the ID, and verify the Ed25519 signature — and all reproduce the vectors byte for byte.

Use it

# Dump + verify an envelope (hex or ~S1.…~ armor) — pick any decoder:
python3 reference/spore_t0.py '~S1.AEAB….~'
cc -O2 -o /tmp/spore_t0 reference/spore_t0.c && /tmp/spore_t0 '010012…'
echo '010012…' | bash reference/spore_t0.sh

# Conformance tests:
python3 reference/test_t0.py        # Python
bash reference/test_decoders.sh     # C + shell

Why this exists

A node you can read in one sitting, in a language that's on almost every machine, with no packages to install, is the most portable seed of the protocol. If the Rust build is unavailable, this file — plus docs/REBUILD.md — is enough to rebuild a compatible node and rejoin the mesh. The Python verify is correct but intentionally simple (and slow); it's a reference, not a fast library.

The C and shell ports extend this to boxes with a compiler or just the usual Unix tools; the vectors here make them straightforward to validate.