feat(grpc): add earliest/latest block height to GetSyncing response

[Cordtus]

Description

Ref: #15463

This PR extends the GetSyncingResponse in cosmos.base.tendermint.v1beta1.Service to include block height information that is essential for indexers and tooling.

Problem

Indexers need to know which blocks are available on a node before attempting to fetch them. Currently, this information is only available via CometBFT's /status RPC endpoint (sync_info.earliest_block_height), requiring clients to query two different endpoints.

When an indexer tries to fetch a pruned block, it gets an error like:

height 60 is not available, lowest height is 28566001

Discovering available block heights proactively via gRPC would be more efficient.

Solution

Add two new fields to GetSyncingResponse:

• earliest_block_height - The earliest block height available on this node
• latest_block_height - The latest block height available on this node

These fields expose the same information as CometBFT's SyncInfo struct, making it available via the existing gRPC endpoint without requiring a separate RPC call.

Changes

File	Change
proto/cosmos/base/tendermint/v1beta1/query.proto	Add new fields to GetSyncingResponse
client/grpc/cmtservice/query.pb.go	Generated code with new fields
client/grpc/cmtservice/service.go	Populate new fields from SyncInfo
tests/systemtests/cometbft_service_test.go	Add systemtest with pruning verification

API

message GetSyncingResponse {
  bool syncing = 1;
  int64 earliest_block_height = 2;  // NEW
  int64 latest_block_height = 3;    // NEW
}

Testing

Systemtest added (TestCometBFTGetSyncingGRPC and TestCometBFTGetSyncingWithBlockRetention) that:

1. Verifies gRPC endpoint returns valid block heights
2. Confirms latest_block_height increases over time
3. Confirms earliest_block_height is stable on unpruned chains
4. Verifies pruning behavior: Configures min-retain-blocks=5 and max_age_num_blocks=5 (in genesis), then confirms earliest_block_height increases as blocks are pruned

The pruning test required modifying both app.toml (via EditToml) and genesis params (via ModifyGenesisJSON) because CometBFT's block retention is the minimum of min-retain-blocks and max_age_num_blocks. Default max_age_num_blocks=100000 would prevent pruning in tests.

=== RUN   TestCometBFTGetSyncingWithBlockRetention
    Initial state: earliest=1, latest=5
    Waiting for 15 blocks to trigger block pruning (minRetainBlocks=5)...
    After 15 blocks: earliest=15, latest=20
    Block range: 5 (latest 20 - earliest 15)
--- PASS: TestCometBFTGetSyncingWithBlockRetention (56.35s)

Backward Compatibility

This is a non-breaking change - it only adds new optional fields to an existing response message. Existing clients will continue to work unchanged.

Use Case

// Before: Need to query CometBFT RPC separately
status, _ := rpcClient.Status(ctx)
earliest := status.SyncInfo.EarliestBlockHeight

// After: Available via gRPC
resp, _ := cmtClient.GetSyncing(ctx, &GetSyncingRequest{})
earliest := resp.EarliestBlockHeight

[fmorency]

This would be useful for manifest-network/yaci#28

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.43%. Comparing base (18e85de) to head (117246f).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #25648      +/-   ##
==========================================
+ Coverage   70.40%   70.43%   +0.03%     
==========================================
  Files         830      830              
  Lines       54050    54052       +2     
==========================================
+ Hits        38052    38070      +18     
+ Misses      15998    15982      -16     

Files with missing lines	Coverage Δ
client/grpc/cmtservice/service.go	84.05% <100.00%> (+0.23%)	⬆️

... and 2 files with indirect coverage changes

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[Cordtus]

Added a systemtest. Run with:

cd tests/systemtests && go test -tags='system_test' -v --run 'TestCometBFT' --wait-time=120s --nodes-count=1

The pruning test configures min-retain-blocks=5 in app.toml and max_age_num_blocks=5 in genesis (Comet block retention uses the minimum of both), waits 15 blocks, then confirms earliest_block_height increases from 1 to 15 as blocks get pruned.