[evanlinjin]

Builds on #2139: review only the last commit. The first commit is #2139 squashed onto master, to be dropped when rebasing onto #2139 once it lands.

Closes #2201
Replaces #2219

Description

Canonical::txs() now yields parents before children, deterministically. Before, it followed the order txs were canonicalized in.

Canonical::order is built with Kahn's algorithm, taking the smallest ready tx first:

• CanonicalTask::finish: by txid.
• CanonicalViewTask::finish: by ChainPosition (confirmed by anchor, then unconfirmed by first seen), then txid. So a wallet's tx list shows confirmed txs before unconfirmed ones wherever the spends allow.

Notes to the reviewers

• Kahn runs twice (once per task), because the view's key only exists after phase 2. This is a non-issue for performance: on the canonicalization bench, the worst case (many_chained_unconfirmed, 2100 chained txs) costs about 1 ms for both passes; the other benches barely move.
• Not by level, as proposed in refactor(chain): add CanonicalView topological ordering #2219 (comment): level order puts an unconfirmed tx before a confirmed one deeper in the graph.
• vs refactor(chain): add CanonicalView topological ordering #2219: the order is what txs() returns, built once per view, not a separate method that sorts on every call.

Changelog notice

bdk_chain

• Changed: Canonical::txs (and so CanonicalView/CanonicalTxs) yields transactions in topological order, parents before children. Otherwise a CanonicalView orders them by ChainPosition, then txid. #

Checklists

All Submissions:

• I followed the contribution guidelines

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 95.76108% with 22 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.47%. Comparing base (02b7b12) to head (f8a94cc).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/chain/src/canonical_view_task.rs	91.42%	11 Missing and 1 partial ⚠️
crates/chain/src/canonical_task.rs	94.56%	5 Missing ⚠️
crates/chain/src/indexed_tx_graph.rs	0.00%	2 Missing ⚠️
crates/chain/src/local_chain.rs	95.83%	1 Missing and 1 partial ⚠️
crates/chain/src/canonical.rs	99.08%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2464      +/-   ##
==========================================
+ Coverage   83.25%   83.47%   +0.21%     
==========================================
  Files          31       32       +1     
  Lines        6236     6494     +258     
  Branches      293      298       +5     
==========================================
+ Hits         5192     5421     +229     
- Misses        976     1010      +34     
+ Partials       68       63       -5     

Flag	Coverage Δ
rust	83.47% <95.76%> (+0.21%)	⬆️

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