Blocks and transaction verification fails on `testing-preview`

[jpraynaud]

Why

This client command fails in the nightly test (reproduced locally) with a internal error of the aggregator:

./mithril-client  --origin-tag CI cardano-transaction certify 1f7dbc899a898ceb4274bbc33b31ca5f0de497753c6c6795fa34838fc252de9b,c43e809de628f7c1ba41a44f188ed3872bb1f97aa101271e35424a8e1d95bea9,c61e22ac4a79a02b28ed36217369ff6959465790a4fe9e66738b7a820e174fcd  --backend v2 --unstable                                                                                                                                                      
Mithril Client CLI version: 0.13.23+a47109c
1/4 - Fetching a proof for the given transactions…                                                                                                                                                                                                                                        Error: Can not get proof from aggregator, transactions hashes: '["1f7dbc899a898ceb4274bbc33b31ca5f0de497753c6c6795fa34838fc252de9b", "c43e809de628f7c1ba41a44f188ed3872bb1f97aa101271e35424a8e1d95bea9", "c61e22ac4a79a02b28ed36217369ff6959465790a4fe9e66738b7a820e174fcd"]'

Caused by:
    0: Failed to get Cardano transactions proofs for hashes '["1f7dbc899a898ceb4274bbc33b31ca5f0de497753c6c6795fa34838fc252de9b", "c43e809de628f7c1ba41a44f188ed3872bb1f97aa101271e35424a8e1d95bea9", "c61e22ac4a79a02b28ed36217369ff6959465790a4fe9e66738b7a820e174fcd"]'
    1: Internal error of the Aggregator
    2: internal server error: Resource pool 'acquire_resource' has timed out
       
       Caused by:
           Acquire resource has timed out

What

Investigate the source of the problem and apply a fix if needed.

How

• Investigate the source of the problem:
  • Discrepancy found in testing-preview and testing-2-preview aggregators
  • Why the rollback mechanism did not work for the aggregators?
• Apply a fix:
  • Short term fix: Reset the block range root store for Cardano blocks and transactions of the aggregator (and remove the wrong blocks)

[jpraynaud]

Problem

No CardanoBlocksTransactions certificate has been produced on testing-preview since
2026-09-04T09:15:41Z (last artifact: block_number_signed 4630440). Every single signature
from the 3 signers is rejected with Invalid single signature for CardanoBlocksTransactions(...).
CardanoTransactions (v1) signing is unaffected.

Visible side effect: /proof/v2/cardano-transaction answers
500 internal server error: Resource pool 'acquire_resource' has timed out, because the v2 prover
Merkle map pool is only filled when a CardanoBlocksTransactions artifact is built, and none has
been built since.

Diagnosis

Comparing the cardano-transaction.sqlite3 stores of the aggregator, signer-1 and signer-2:

• block_range_root: exactly 1 differing row out of 309,575, for block range [4630440, 4630455)
  • aggregator: d48a53251e074dff7bb50bd820e17dd4b14ef6876d6c40e5cf088e11cf235145
  • signer-1 and signer-2 (identical): ce64745fa9428694361fc2b879a403ce44c62b3161fd6ce23b462dc00a6df9df
• block_range_root_legacy: 0 differing rows out of 302,844
• overlapping raw blocks and transactions between the three stores: no difference

The signed message is the Merkle map root over every block range root with start < beacon, so this
single row breaks every beacon from 4630455 onward, permanently. Beacon 4630440 is the last one that
excludes it, which is exactly the last certificate produced.

Contributing factors:

• security_parameter = 0 for CardanoBlocksTransactions: blocks are imported and rooted up to the
  tip, before short forks are settled