lnwallet+rpc: add label filter to GetTransactions

[saraogiraj94]

Closes #10785

Summary

• Adds an optional label field (proto field 6) to GetTransactionsRequest so callers can filter chain transactions by their label
• WalletController.ListTransactionDetails gains a labelFilter string parameter; when non-empty, only transactions whose Label field exactly matches are returned
• lncli listchaintxns gains a --label flag

Testing

• All existing mocks and integration-test call sites updated to pass the new parameter
• New integration test testListTransactionDetailsLabelFilter covers: exact match by label A, exact match by label B, no filter returns all, unknown label returns empty

Release Notes

Updates docs/release-notes/release-notes-0.22.0.md under RPC Additions and lncli Additions.

🤖 Generated with Claude Code

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces label-based filtering for chain transactions across the RPC, CLI, and internal wallet interfaces. By allowing users to filter transactions by a specific label, it improves the discoverability and management of wallet activity. The changes include updates to the gRPC definition, internal wallet controller logic, and command-line interface, accompanied by comprehensive integration tests to ensure correctness.

Highlights

• RPC API Update: Added an optional label field to GetTransactionsRequest to allow filtering chain transactions by label.
• Wallet Controller Enhancement: Updated WalletController.ListTransactionDetails to accept a labelFilter parameter for precise transaction retrieval.
• CLI Tooling: Introduced a new --label flag to the listchaintxns command in lncli.
• Testing: Implemented a new integration test testListTransactionDetailsLabelFilter to verify exact label matching and empty result scenarios.

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[gemini-code-assist]

Code Review

This pull request introduces an optional "label" filter to the GetTransactions RPC and the listchaintxns CLI command, allowing users to filter transactions by their exact label. The changes span the API definitions, the wallet controller interface, and the btcwallet implementation, supported by new integration tests. Review feedback highlighted a placeholder PR number in the release notes that needs updating and noted significant formatting regressions in the generated gRPC code, suggesting the file be regenerated using the standard project toolchain to reduce diff noise.

[github-actions]

PR Severity: CRITICAL - lnwallet and rpcserver.go changes require expert review. <!-- pr-severity-bot -->

[github-actions]

PR Severity: CRITICAL

Automated classification | 9 files | 210 lines changed (excluding auto-generated and test files)

Critical (5 files):

• lnwallet/btcwallet/btcwallet.go - Wallet operations (lnwallet/*)
• lnwallet/interface.go - Core wallet interface (lnwallet/*)
• lnwallet/mock.go - Wallet mock (lnwallet/*)
• lnwallet/test/test_interface.go - Wallet test interface (lnwallet/*)
• rpcserver.go - Core server coordination

High (2 files):

• lnrpc/lightning.proto - RPC/API definitions (lnrpc/*)
• lnrpc/lightning.swagger.json - RPC/API definitions (lnrpc/*)

Medium (1 file): cmd/commands/commands.go
Low (1 file): docs/release-notes/release-notes-0.22.0.md
Excluded (auto-gen/test): lnrpc/lightning.pb.go, lnrpc/lightning_grpc.pb.go, lntest/mock/walletcontroller.go

Analysis: This PR modifies lnwallet/* and rpcserver.go, both CRITICAL. The wallet interface change (lnwallet/interface.go) affects channel funding, signing, and commitment transactions. The lnrpc proto addition adds new RPC surface. No severity bump: 9 files (threshold 20) and 210 lines (threshold 500).

To override: add a severity-override-{critical,high,medium,low} label.
<!-- pr-severity-bot -->