[ZocoLini]

Closes #1130. Part of #1047.

A transaction with a special type we don't know failed to decode (UnknownSpecialTransactionType), and with it the whole block, so a new Core tx type would stall SPV sync and get_block consumers.

Changes

• TransactionType::Unknown(u16) and TransactionPayload::UnknownPayloadType(u16, Vec<u8>): the payload is read through its length prefix and written back verbatim, so the tx re-encodes to the same bytes and txid.
• Unknown types are non-segwit, like the other special types (an input-less one would otherwise be read as BIP144).
• key-wallet router: matches on tx.tx_type() instead of the payload variant (same result). Unknown types are classified by shape like classic txs, so every fund-bearing account is checked.

Breaking: new enum variants on public, exhaustive enums.

Out of scope

• Known types with a new payload version (CbTx v4, ProRegTx v3) still misalign the block: dash: decode and encode CbTx v4 (merkleRootAssetUnlocks) #1129, dash: parse ProRegTx v3 layout #1132, dash: parse ProUpServTx and ProUpRegTx v3 (ExtAddr) #1133.
• Version 1/2 txs with non-zero type bits are still read as special: dash: only decode a special payload for tx version >= 3 #1135.

Testing

• Unit: round trip (bytes, txid, size), stream alignment across two txs, input-less unknown type, router classification.
• cargo test -p dashcore -p key-wallet, cargo test -p dash-spv with dashd integration tests, clippy -D warnings.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Unknown transaction types can now be encoded and decoded, including transactions with no inputs.
  • Unknown transaction types and their payloads are preserved when processing transactions.
  • Transactions that follow an unknown transaction are decoded correctly.
  • Unknown transactions are classified as standard unless their contents indicate a coinbase or CoinJoin transaction.

PR Hygiene · 249ef12

• Bots — coderabbitai ✓
• Self-review — post /self-reviewed
• Build green
• Approvals
  • files with no dedicated owner (dash/src/blockdata/transaction/mod.rs, dash/src/blockdata/transaction/special_transaction/mod.rs, dash/src/test_utils/mod.rs and 1 more) — QuantumExplorer or xdustinface
  • key-wallet (key-wallet/src/transaction_checking/transaction_router/mod.rs, key-wallet/src/transaction_checking/transaction_router/tests/classification.rs) — QuantumExplorer or xdustinface

When every merge requirement is met, the PR Hygiene check passes. Reviewer limits do not block merging; other required GitHub checks and protections still apply.

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Repository: dashpay/rust-dashcore/.coderabbit.yaml
• Review profile: CHILL
• Plan: Advanced
• Run ID: d5173613-c377-4abd-9747-59a907636bce

📥 Commits

Reviewing files that changed from the base of the PR and between 6d48530 and 249ef12.

📒 Files selected for processing (4)

• dash/src/blockdata/transaction/mod.rs
• dash/src/test_utils/mod.rs
• dash/src/test_utils/transaction.rs
• key-wallet/src/transaction_checking/transaction_router/tests/classification.rs

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📝 Walkthrough

Walkthrough

Unknown special transaction types now retain their raw type and payload through encoding and decoding. Transactions with unknown types use non-SegWit framing. The wallet transaction router classifies unknown types by transaction shape.

Changes

Unknown transaction support

Layer / File(s)	Summary
Unknown payload representation and codec dash/src/blockdata/transaction/special_transaction/mod.rs	TransactionPayload and TransactionType now represent unknown special transaction types. Encoding and decoding preserve the raw type and payload bytes, including the length prefix.
Transaction wire handling dash/src/blockdata/transaction/mod.rs, dash/src/test_utils/transaction.rs, dash/src/test_utils/mod.rs	Transaction encoding and decoding use non-SegWit framing for unknown types. Tests cover round trips, txid preservation, stream alignment, and transactions with no inputs. Test utilities expose the unassigned type constant.
Wallet transaction classification key-wallet/src/transaction_checking/transaction_router/mod.rs, key-wallet/src/transaction_checking/transaction_router/tests/classification.rs	The router classifies transactions by type. Unknown types fall back to coinbase, CoinJoin, or Standard based on transaction shape. A test checks that an unknown special payload is classified as Standard.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 249ef

No actionable issue was established in the reviewed unknown-transaction codec, wire framing, or wallet classification changes; no identified risk blocks merging.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 71.43% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 21 functions across 6 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: decoding unknown special transaction types as raw payloads.
Linked Issues check	✅ Passed	Issue [#1130] requires unknown special transaction types to decode without failing block decoding and to retain the length-prefixed payload as raw bytes. The PR adds TransactionType::Unknown(u16) an…
Out of Scope Changes check	✅ Passed	The transaction changes implement [#1130]. The key-wallet router change handles the new public transaction variant, and its classification test verifies unknown transaction handling. The shared test c…

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[codecov]

Codecov Report

❌ Patch coverage is 96.34146% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.09%. Comparing base (67b307c) to head (249ef12).
⚠️ Report is 3 commits behind head on dev.

Files with missing lines	Patch %	Lines
...c/blockdata/transaction/special_transaction/mod.rs	80.00%	2 Missing ⚠️
...src/transaction_checking/transaction_router/mod.rs	92.85%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1136      +/-   ##
==========================================
+ Coverage   77.92%   78.09%   +0.16%     
==========================================
  Files         302      302              
  Lines       79108    79315     +207     
==========================================
+ Hits        61644    61938     +294     
+ Misses      17464    17377      -87     

Flag	Coverage Δ
core	75.23% <97.05%> (+0.26%)	⬆️
ffi	51.84% <ø> (+0.68%)	⬆️
rpc	49.21% <ø> (+0.25%)	⬆️
spv	92.43% <ø> (+0.03%)	⬆️
wallet	81.99% <92.85%> (+<0.01%)	⬆️

Files with missing lines	Coverage Δ
dash/src/blockdata/transaction/mod.rs	88.16% <100.00%> (+1.25%)	⬆️
...src/transaction_checking/transaction_router/mod.rs	91.45% <92.85%> (+1.20%)	⬆️
...c/blockdata/transaction/special_transaction/mod.rs	40.27% <80.00%> (+2.11%)	⬆️

... and 29 files with indirect coverage changes

[xdustinface]

Two test issues before this can merge:

1. unknown_special_transaction_type_without_inputs_is_not_segwit passes even without the fix. It only checks encode → decode → encode. If you revert both Unknown(_) segwit lines, the encoder writes the BIP144 marker 00 01 and the decoder reads it straight back, so the round trip still passes. Please assert the wire bytes instead. Either assert_eq!(bytes.len(), tx.size()) works, or check that bytes[4..6] == [0x00, 0x01] is followed directly by the output value.

2. The tests use type 10, which Core develop already assigns to TRANSACTION_PROVIDER_DISSOLVE. Once dash: add payloads for special tx types 10-12 (ProDisTx, ProUpShareTx, ProUpSharedRegTx) #1131 adds parsing for types 10 to 12, Unknown(10) stops being unknown and all four new tests fail. That includes the router test in classification.rs. The TODO has the same problem: a real ProDisTx vector would no longer exercise the unknown-type path at all. Please switch to a type nobody has assigned (e.g. 0xffff, ideally behind a shared const), and drop or reword the TODO.

[ZocoLini]

Done

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