[evanlinjin]

Description

Makes the rest of bdk_chain's accidentally BlockHash-only API generic over the checkpoint data D:

• LocalChain::{is_block_in_chain, chain_tip, canonicalize, canonical_view}: their impl LocalChain<BlockHash> block becomes impl<D> LocalChain<D>, and apply_header* get a BlockHash block of their own. The four only use get/hash/block_id, so a LocalChain<Header> can now canonicalize a TxGraph.
• SyncRequestBuilderExt and FullScanRequestBuilderExt are implemented for builders with any D, so revealed_spks_from_indexer, unused_spks_from_indexer and spks_from_indexer work with a CheckPoint<Header> tip.

The rest of the BlockHash-only API is that way on purpose: apply_header* build BlockHash checkpoints, the sqlite local_chain::ChangeSet stores hashes, the chain sources fetch hashes, and SyncRequestBuilder<()>::spks stays BlockHash-only so SyncRequest::builder().spks(..) keeps inferring D.

Fixes #2437

Replaces #2438, adding the LocalChain methods and leaving out its unrelated MSRV pin change (#2435 has it).

Notes to the reviewers

None of this API is released (chain-0.23.x has a non-generic LocalChain, core-0.6.x builders have no D), so there's no changelog entry.

This conflicts with #2139, which moves is_block_in_chain into the D: ToBlockHash impl and renames canonicalize/canonical_view. This is the smaller fix; #2139 can rebase onto it.

Against master, this can break type inference where nothing else pins D:

• A LocalChain built from generic data (e.g. Hash::hash(..)) whose only use was canonicalize/canonical_view. Two tests here needed a LocalChain<BlockHash> annotation.
• A request built with revealed_spks_from_indexer/spks_from_indexer, without chain_tip, and never passed to a chain source. Passing it to esplora/electrum sync/full_scan still infers D.

Changelog notice

None: fixes unreleased API.

Checklists

All Submissions:

• I followed the contribution guidelines

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.23%. Comparing base (7b68d28) to head (0b280d9).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2439      +/-   ##
==========================================
+ Coverage   80.66%   81.23%   +0.57%     
==========================================
  Files          31       31              
  Lines        6236     6236              
  Branches      293      294       +1     
==========================================
+ Hits         5030     5066      +36     
+ Misses       1136     1100      -36     
  Partials       70       70              

Flag	Coverage Δ
rust	81.23% <ø> (+0.57%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[reez]

ACK 0b280d9