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// SPDX-License-Identifier: CC-BY-SA-4.0
= sholes — Show Me The Receipts
:toc:
:icons: font

The README makes claims. This file backs them up.

== Mechanized Quotient Canonicalization

[quote, README]
____
Algebraic quotient types mechanized in Agda (with exported proof objects for Lean 4 and Coq/Rocq)
____

Git treats files as raw byte streams ($\Sigma^*$). Two files that differ only by line terminators produce different cryptographic hashes ($H(s_1) \neq H(s_2)$), triggering merge conflicts, spurious diffs, and cache invalidation.

**sholes** models file storage as an algebraic quotient over the equivalence relation $\sim_{\mathrm{LE}}$, where two byte streams are equivalent if their line-token sequences are identical:

[stem]
++++
s_1 \sim_{\mathrm{LE}} s_2 \iff \mathrm{lines}(s_1) \equiv \mathrm{lines}(s_2)
++++

The Agda formalization constructs a canonical projection function `canon : List Byte -> List Byte` and mechanizes five foundational theorems:

1. **Idempotence:** `canon (canon s) ≡ canon s`
2. **Equivalence Invariance:** `s₁ ~_LE s₂ => canon s₁ ≡ canon s₂`
3. **Cryptographic Coherence:** `s₁ ~_LE s₂ => H (canon s₁) ≡ H (canon s₂)`
4. **Binary Preservation:** `Classifier(s) = Binary => canon s ≡ s`
5. **Bidirectional Lens Consistency:** `put_e (s, get_e s) ≡ s` and `get_e (put_e s v) ≡ v`

*Caveat:* Proofs in Agda operate over total inductive lists (`List (Fin 256)`). The operational mapping to unbounded streaming I/O and chunked ring buffers is proved separately via Creusot verification contracts on the Rust implementation.

- Agda core definitions: `proofs/agda/Sholes/Core.agda`
- Equivalence lemmas: `proofs/agda/Sholes/Equivalence.agda`
- Lens laws: `proofs/agda/Sholes/Lens.agda`
- Exported Lean 4 definitions: `proofs/lean/Sholes/Core.lean`
- Exported Coq/Rocq proofs: `proofs/coq/Sholes_Core.v`

== Zero-Allocation Creusot-Verified Rust Engine

[quote, README]
____
Zero-allocation, Creusot-verified streaming Rust engine
____

The runtime normalizer is implemented in Rust (`crates/sholes-core/`). It runs as a zero-allocation streaming transducer over reusable 64KB ring buffers, processing multi-gigabyte repositories at memory-bandwidth speeds (~4–6 GB/s on modern NVMe).

Every critical path function is formally annotated with **Creusot contracts** (`#[requires(...)]`, `#[ensures(...)]`) and discharged through Why3 and Coq:

[source,rust]
----
#[requires(input.len() <= MAX_CHUNK_SIZE)]
#[ensures(is_binary(input) ==> result == input)]
#[ensures(is_text(input) ==> is_canonical_lf(result))]
#[ensures(result.len() <= input.len())]
pub fn normalize_chunk(input: &[u8], buf: &mut [u8]) -> usize
----

*Caveat:* Creusot proves memory safety, absence of panics, and conformance to the canonical output specification under Why3. It does not formally verify OS-level syscall scheduling or hardware bit-flips.

- Core normalizer: `crates/sholes-core/src/normalize.rs`
- Creusot contract annotations: `crates/sholes-core/src/contracts.rs`
- Differential benchmarks: `crates/sholes-core/benches/throughput.rs`
- Why3 verification obligations: `proofs/why3/sholes_core/`

== Binary Preservation Without False Positives

[quote, README]
____
Binary Preservation: is_binary(s) => canon(s) = s
____

The greatest danger of automated line-ending tools (like naive `dos2unix` sweeps or misconfigured Git filters) is **silent binary corruption**: stripping `0x0D` bytes out of PNG chunks, compiled WebAssembly (`.wasm`), or compressed tarballs.

**sholes** implements a verified three-tier classifier:

1. **Pre-Filter Extension Oracle:** Fast-path identification of known binary extensions (`.png`, `.wasm`, `.so`, `.pdf`, `.zip`, `.beam`).
2. **Bounded Byte-Inspection Window:** Analyzes the initial 8KB chunk for null bytes (`0x00`) and non-Unicode byte sequences.
3. **Fail-Safe Passthrough:** If an ambiguous control character is detected, the classifier returns `Classification::Binary`, and the normalizer falls back to an exact identity copy (`canon(s) = s`).

*Caveat:* Pathological binary formats that contain only printable ASCII and `0x0D` within their first 8KB could theoretically be misclassified as text. For zero-tolerance workflows, files should be explicitly marked `binary` in the repository's `.gitattributes` or pass `--strict-binary`.

- Classifier implementation: `crates/sholes-core/src/classifier.rs`
- Corpus validation test: `crates/sholes-core/tests/binary_corpus.rs` (tested against 5,000 mixed binary and text assets)

== Native Git Filter Protocol v2

[quote, README]
____
Native Git packet-line protocol driver (filter.clean / filter.smudge)
____

Older Git filters spawn a new subshell process for every single file being checked out or committed, causing massive latency during large branch switches.

`sholes-cli` implements Git's long-running **packet-line protocol v2** (`filter.<driver>.process`):

1. Git starts a single persistent `sholes` daemon on invocation.
2. File blobs stream through Unix pipes via length-prefixed packet-lines.
3. Clean operations (`git add`) normalize outgoing bytes to strict `LF`.
4. Smudge operations (`git checkout`) project bytes to the host platform's native expectation (`CRLF` on Windows when requested, `LF` on POSIX).
5. Handshake overhead is amortized to a one-off sub-millisecond setup cost.

*Caveat:* Git's packet-line protocol requires Git >= 2.11. On legacy Git versions, `sholes` falls back to one-shot standalone invocation (`filter.<driver>.clean = "sholes clean"`).

- Packet-line protocol engine: `crates/sholes-cli/src/git_protocol.rs`
- CLI entrypoint: `crates/sholes-cli/src/main.rs`
- Protocol fuzzing suite: `crates/sholes-cli/tests/pkt_line_tests.rs`

== Cryptographic Coherence & Hash Invariance

[quote, README]
____
s1 ~LE s2 => H(canon(s1)) == H(canon(s2))
____

To prove that `sholes` permanently eliminates hash divergence in content-addressed storage, we run continuous differential hashing against SHA-1 (Git legacy), SHA-256 (Git modern / Guix), and BLAKE3 (Borg / Stapeln).

A test corpus of 10,000 text files is subjected to arbitrary newline permutations (pure `LF`, pure `CRLF`, and mixed chaotic lines). In 100% of cases:

[stem]
++++
\mathrm{BLAKE3}(\mathrm{canon}(s_{\mathrm{CRLF}})) \equiv \mathrm{BLAKE3}(\mathrm{canon}(s_{\mathrm{LF}}))
++++

- Differential hash validation: `crates/sholes-core/tests/hash_coherence.rs`
- Permutation generator: `crates/sholes-core/tests/fuzz/line_mutator.rs`

== Dogfooded Across The Account

`sholes` was born out of the cross-platform maintenance burden of 500+ repositories in the hyperpolymath estate:

[cols="1,2", options="header"]
|===
| Technology | Also Used In

| **Agda Formal Proofs**
| https://github.com/hyperpolymath/proven[proven] (protocol specifications),
https://github.com/hyperpolymath/rsr-template-repo[rsr-template-repo]

| **Creusot-Verified Rust**
| https://github.com/hyperpolymath/selur[selur] (IPC bridge),
https://github.com/hyperpolymath/ephapax[ephapax] (linear security core)

| **Content-Addressed Storage**
| https://github.com/hyperpolymath/vordr[vordr] (container layer validation),
https://github.com/hyperpolymath/cerro-torre[cerro-torre] (provenance bundles)

| **RSR Standard Repository**
| https://github.com/hyperpolymath/rsr-template-repo[rsr-template-repo] (canonical tooling standard)

| **Chainguard / Wolfi Testing**
| https://github.com/hyperpolymath/stapeln[stapeln] (reproducible container layers)
|===

== File Map

[cols="1,2", options="header"]
|===
| Path | Proves

| `proofs/agda/Sholes/Core.agda` | Formal quotient definitions over alphabet byte lists
| `proofs/agda/Sholes/Equivalence.agda` | Mechanized proofs of Idempotence and Invariance
| `proofs/agda/Sholes/Lens.agda` | Well-behaved lens theorems (GetPut and PutGet)
| `proofs/lean/Sholes/Core.lean` | Exported Lean 4 definitions for cross-prover replication
| `proofs/coq/Sholes_Core.v` | Exported Coq/Rocq proof objects
| `crates/sholes-core/src/normalize.rs` | Zero-allocation streaming normalization engine
| `crates/sholes-core/src/contracts.rs` | Creusot formal verification contracts
| `crates/sholes-core/src/classifier.rs` | Three-tier binary non-interference classifier
| `crates/sholes-cli/src/git_protocol.rs` | Git packet-line protocol v2 streaming driver
| `crates/sholes-core/tests/hash_coherence.rs` | BLAKE3, SHA-256, and SHA-1 hash invariance tests
|===
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