refactor!: harmonize workspace crates behind hex-conservative 1.x

[kwvg]

Motivation

The Rust ecosystem provides a plethora of hex encoding crates, each of them with different APIs, encoding/decoding behaviours and semantics. hex-conservative, the crate published by rust-bitcoin is one of them but it only one of many. The problem with using these crates interchangeably is that differences in semantics can result in parsing bugs due to mismatched assumptions and invariants between crates.

Furthermore, portions of rust-dashcore already have inline parsing routines mixed with ownership of a hex module in dashcore-internal and some unused serde utility macros on top of using two different dependencies, hex and hex_lit in different workspace crates.

While rust-dashcore#1108 does forward the hex module from bitcoin-hashes 0.14, that in effect propagates hex-conservative 0.2 throughout the codebase. To front load the effort of having to migrate to hex-conservative 1.x through rust-bitcoin#5710 and rust-bitcoin#6148, this pull request also replaces the export from bitcoin-hashes with hex-conservative 1.x. See rust-dashcore#1110.

Additional Information

• Depends on refactor!: consolidate common definitions to workspace Cargo.toml, bump base58ck to 0.5.0, pass through definitions from bitcoin-{hashes,internals,crypto} and dash-pkc #1108

• Dependency for refactor!: drop dashcore_hashes::hex in favour of hex-conservative, ban hex{,_lit,-literal} with cargo deny #1110

• This pull request was originally the first half of rust-dashcore#1110 but was split into two as a workaround for CodeRabbit's 100 files changed upper limit.

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📥 Commits

Reviewing files that changed from the base of the PR and between fc4e10b and a4be8ac.

📒 Files selected for processing (8)

• dash-spv/src/client/queries.rs
• dash-spv/src/validation/chainlock.rs
• dash-spv/src/validation/instantlock.rs
• dash/Cargo.toml
• dash/src/sml/masternode_list/apply_diff.rs
• key-wallet-ffi/Cargo.toml
• key-wallet/Cargo.toml
• key-wallet/README.md

🚧 Files skipped from review as they are similar to previous changes (2)

• key-wallet/README.md
• dash-spv/src/client/queries.rs

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---

📝 Walkthrough

Walkthrough

The workspace replaces hex and hex_lit with hex-conservative for hexadecimal decoding, formatting, and Serde support. BLS parsing and RPC JSON error types change. Other summarized conversions retain the existing output formats, fixtures, and assertions.

Changes

Hexadecimal conversion migration

Layer / File(s)	Summary
Workspace dependency and BLS decoding Cargo.toml, crypto/Cargo.toml, crypto/src/bls.rs, CHANGELOG.md	The workspace adds hex-conservative and removes hex and hex_lit. BLS public-key and signature parsing use fixed-length decoding and return DecodeFixedLengthBytesError.
RPC JSON hex adapter rpc-json/Cargo.toml, rpc-json/src/lib.rs	RPC JSON byte fields use a private Serde adapter backed by hex-conservative. HexError wraps DecodeVariableLengthBytesError, and a round-trip test checks lowercase hex serialization and deserialization.
Dash and SPV conversion sites dash-spv/..., dash/...	Dash and SPV decoding and formatting calls use hex-conservative. The summarized changes retain existing hash lengths, error handling, fixtures, and assertions.
Wallet conversion sites key-wallet/..., key-wallet-ffi/..., key-wallet-manager/...	Wallet crates, examples, documentation, and tests use hex-conservative for hexadecimal decoding and lowercase formatting. The summarized derivation vectors and expected values remain unchanged.
FFI and RPC conversions dash-spv-ffi/..., rpc-client/..., rpc-integration-test/...	FFI output, RPC client conversions, and integration tests use hex-conservative. The described output remains lowercase hexadecimal.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Other

Merge Risk: ⚪ Minimal · up to a4be8

The reviewed migration preserves the identified length checks, byte ordering, and RPC JSON hex format. No actionable merge-blocking regression is established; malformed-input compatibility remains unverified.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 76.26% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 139 functions across 53 files. (4 skipped…	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: standardizing workspace crates on hex-conservative 1.x. The refactor! marker also communicates the breaking nature of the change.

Full details: Docstring Coverage

Explanation

Docstring coverage is 76.26% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 139 functions across 53 files. (4 skipped: 4 unsupported.)

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[codecov]

Codecov Report

❌ Patch coverage is 85.00000% with 39 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.92%. Comparing base (c5a9b94) to head (a4be8ac).

Files with missing lines	Patch %	Lines
dash-spv-ffi/src/bin/ffi_cli.rs	0.00%	9 Missing ⚠️
dash/src/network/constants.rs	25.00%	9 Missing ⚠️
dash/src/sml/masternode_list/debug_helpers.rs	0.00%	5 Missing ⚠️
key-wallet-ffi/src/account_derivation.rs	25.00%	3 Missing ⚠️
dash-spv-ffi/src/callbacks.rs	77.77%	2 Missing ⚠️
dash-spv/src/chain/chain_work.rs	0.00%	2 Missing ⚠️
key-wallet-ffi/src/account.rs	0.00%	2 Missing ⚠️
rpc-client/src/client.rs	33.33%	2 Missing ⚠️
dash-spv/src/client/queries.rs	0.00%	1 Missing ⚠️
key-wallet-ffi/src/keys.rs	0.00%	1 Missing ⚠️
... and 3 more

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1115      +/-   ##
==========================================
- Coverage   77.96%   77.92%   -0.05%     
==========================================
  Files         302      302              
  Lines       79049    79108      +59     
==========================================
+ Hits        61634    61647      +13     
- Misses      17415    17461      +46     

Flag	Coverage Δ
core	74.96% <85.26%> (+0.01%)	⬆️
ffi	51.15% <32.00%> (-0.54%)	⬇️
rpc	48.95% <88.00%> (+0.25%)	⬆️
spv	92.41% <86.36%> (+0.06%)	⬆️
wallet	81.99% <97.84%> (+<0.01%)	⬆️

Files with missing lines	Coverage Δ
dash-spv/src/chain/checkpoints.rs	98.21% <100.00%> (ø)
dash-spv/src/validation/chainlock.rs	100.00% <100.00%> (ø)
dash-spv/src/validation/instantlock.rs	94.30% <100.00%> (+0.09%)	⬆️
dash/src/address.rs	57.07% <ø> (+0.04%)	⬆️
dash/src/blockdata/constants.rs	100.00% <ø> (ø)
dash/src/blockdata/transaction/mod.rs	86.91% <100.00%> (ø)
...transaction/asset_unlock/qualified_asset_unlock.rs	91.72% <100.00%> (ø)
...n/special_transaction/provider_update_registrar.rs	86.79% <100.00%> (+0.51%)	⬆️
...ion/special_transaction/provider_update_service.rs	82.69% <100.00%> (ø)
...ansaction/special_transaction/quorum_commitment.rs	72.02% <100.00%> (ø)
... and 28 more

... and 20 files with indirect coverage changes

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[ZocoLini]

One thing I'd change: I don't think hex belongs in dashcore_hashes. Re-exporting it
there comes from bitcoin_hashes, which needs hex for its own Display/FromStr, but in
our code hex is a general utility (RPC JSON, FFI, wallet, tests) with nothing to do
with hashing. Pointing dashcore_hashes::hex at hex-conservative 1.x keeps that
coupling in place.

Proposal: a small dedicated crate, e.g. dashcore-hex that:

• re-exports hex_conservative::*
• adds a serde module for Vec/[u8; N] (the serde_hex helper from #1115 moves
  here, since 1.x dropped the upstream one)
• replaces internals::hex, so we end up with exactly one hex module in the workspace

Workspace crates would depend on it directly, and dashcore_hashes would stop exposing
hex. For parsing hash types we keep using FromStr/.parse(), which doesn't need our
crate.

Optionally, dashcore could also re-export it as dashcore::hex, like bitcoin::hex, for
downstream convenience. I'd lean towards not doing that and having consumers depend
on dashcore-hex explicitly, but I'm fine either way.

Do you think you can do this here or you rather prefer to do it in #1110 or in a different PR??