Esplora /address/:a/txs/summary: no tx_position, and a 25-row page where mempool.space returns the whole history #856

Version: observed on aa6de36c (0.7.99), mainnet. The code is unchanged on origin/master 1aece752.

Related: #547 (added the route), #549 ("/txs/summary is a mempool.space dialect"), #814.

What happens

COMPAT.md documents /txs/summary as a mempool.space dialect: "Compact {txid, value, height, time} like mempool.space /address/:addr/txs/summary". The current mempool.space route differs in two ways:

1. Every mempool.space row also carries tx_position, the tx's index in its block. rbitcoin rows have no such field.
2. mempool.space returns the whole confirmed history in one response (268 rows for the address below). rbitcoin returns 25 rows per page with a cursor. The 25-row page is documented in COMPAT.md, but it means a mempool-frontend chart built from this route shows only the newest 25 txs.

$ A=1uv9cJLPtJZswvwzYV4Q78NsfwoEMRMsW
$ curl -s https://mempool.space/api/address/$A/txs/summary | jq 'length, .[0]'
268
{"txid":"6d2a0f0eb72eb8f87946b6f7344f70197ee0a5b78743b4c9f26c882301d8e944","height":969500,"value":-171370299,"time":1790895623,"tx_position":12}

$ curl -s --unix-socket /run/rbitcoin/esplora.sock http://x/address/$A/txs/summary | jq 'length, .[0]'
25
{"height":969500,"time":1790895623,"txid":"6d2a0f0eb72eb8f87946b6f7344f70197ee0a5b78743b4c9f26c882301d8e944","value":-171370299}

txid, height, value and time agree.

Expected

The same row shape as mempool.space, including tx_position. Ideally also a way to get the full summary in one call (mempool.space's page size) for clients that expect it. The 503 cap from --max-sh-creates would still apply.

Source (1aece752)

• ScriptHashTxSummary { txid, value, height } (crates/rbitcoin-query/src/scripthash.rs:44-48) does not carry the position.
• summaries_from_joined (scripthash.rs:220-244) builds it.
• summaries_json (crates/rbitcoin-esplora/src/handlers.rs:1088) adds time only.
• HistoryFilter::esplora_chain_page fixes limit: Some(25) (scripthash.rs:108-116).

The tx's index in its block is already known to the store: the block_tx_fks(height) order is what /block/:h/txids serves.

Also observed (dialect feature)

COMPAT.md lists ?asof= as supported on /txs/summary. On our node it answered 404 Not Found in under 1 ms (both addresses tried), even for a small address where /txs/chain?asof=<same hash> and /address/:a?asof=<same hash> return 200:

/address/1uv9…MsW?asof=<hash of 969500>                200
/address/1uv9…MsW/txs/chain?asof=<hash of 969500>      200
/address/1uv9…MsW/txs/summary?asof=<hash of 969500>    404 Not Found

I have not traced the cause.

Suggested fix

• Add tx_position: u32 to ScriptHashTxSummary and emit it.
• Optionally accept a larger page (or no limit, under the cap) on the summary route, to match mempool.space.
• Look at the asof 404.

Workaround

For each txid, read the position from /tx/:txid and /block/:hash/txids, and page through /txs/summary/:last_seen_txid.