# Base58 And Base62 Codec Review

Date: 2026-06-10
Issue: #63
Branch: `feat/issue-63-base58-base62`

## Scope

Add focused Base58 and Base62 codec primitives to `bluetape-rs-codec`:

- Bitcoin Base58 byte encoding and decoding
- byte-oriented Base62 encoding and decoding
- project-owned typed decode errors
- leading zero byte preservation
- README and README.ko examples
- bounded thread stress tests for stateless encode/decode paths

UUID, integer, ID-generator rendering, checksums, and random string helpers are
intentionally out of scope.

## 7-Tier Review

| Tier | Verdict | Evidence |
|---|---|---|
| 1. Public API / Contract | PASS | Public names expose byte-oriented `encode_base58`, `decode_base58`, `encode_base62`, and `decode_base62` APIs. Decode returns typed `Result<Vec<u8>, ...DecodeError>`. |
| 2. Architecture / Boundary | PASS | The change stays inside `crates/codec` plus README wiring. No UUID, integer, random ID, checksum, serde, or compression behavior is mixed into #63. |
| 3. Rust API Shape | PASS | APIs use `impl AsRef<[u8]>` and `impl AsRef<str>`, owned output values, non-exhaustive error enums, and no unsafe code. |
| 4. Tests | PASS | Unit tests cover empty input, known vectors, binary round trips, leading zero preservation, invalid characters, UTF-8 byte positions, diagnostics, and thread stress round trips. |
| 5. Static / Docs | PASS | Rustdoc examples compile under `RUSTDOCFLAGS="-D warnings"`; README and README.ko expose matching Base58/Base62 examples and compatibility policy. |
| 6. Release / Cargo | PASS | No new third-party dependency is added. `crates/codec/Cargo.toml` keyword metadata is updated only. |
| 7. Evidence Integrity | PASS | Implementation decisions were checked against bluetape4k Kotlin `Base58`, `Base62`, `Url62`, and KSUID `BytesBase62` references before coding. Staged graph review analyzed 10 files with risk score 0.00 and test gaps 0. Native review gates reported P0=0 P1=0. |

## P0/P1 Gate

P0=0 P1=0

- `code-reviewer`: PASS, P0=0 P1=0 P2=0 P3=0.
- `verifier`: PASS, P0=0 P1=0 P2=0. One P3 README current-status clarity gap was fixed before commit.

Higher-level integer/UUID rendering can be tracked separately when the
ID-generator crate scope is planned.

## Validation

- `cargo test -p bluetape-rs-codec stress_round_trips_are_stable_across_threads --all-features --locked`: PASS, 2 stress tests
- `git diff --check`: PASS
- `cargo fmt --all --check`: PASS
- `cargo test -p bluetape-rs-codec --all-features --locked`: PASS, 41 unit tests + 15 doctests
- `cargo test --workspace --all-features --locked`: PASS
- `cargo clippy --workspace --all-targets --all-features --locked -- -D warnings`: PASS
- `RUSTDOCFLAGS="-D warnings" cargo doc --workspace --all-features --no-deps --locked`: PASS
