Multi-account support for transaction submission

[tac0turtle]

Summary

Support submitting blobs from multiple funded accounts to avoid nonce contention when writing to a single namespace at high throughput.

Problem

When a single account submits transactions concurrently, nonce (sequence number) conflicts cause failures:

• Tx A gets nonce 5, Tx B gets nonce 5 → one fails with "account sequence mismatch"
• Serial submission avoids this but kills throughput
• Mempool ordering is not guaranteed, so even sequential nonce assignment can race

Design

Account pool

• Configure multiple funded accounts (key/mnemonic per account)
• Round-robin or least-recently-used assignment when a submission is requested
• Each account manages its own nonce sequence independently

Nonce management

• Track pending nonce per account locally (don't rely solely on on-chain query)
• Increment optimistically on broadcast, roll back on rejection
• Handle sequence mismatch errors by re-querying and retrying from the correct nonce

Configuration

[submission]
enabled = true

[[submission.accounts]]
name = "submitter-1"
key_file = "./keys/submitter-1.json"

[[submission.accounts]]
name = "submitter-2"
key_file = "./keys/submitter-2.json"

[submission.pool]
strategy = "round-robin"  # or "least-pending"
max_pending_per_account = 4

Safety

• Monitor account balances, alert when low
• Cap max pending transactions per account to bound risk
• Graceful degradation: if an account is unhealthy (repeated failures, low balance), remove from rotation

Dependencies

• Requires Evaluate custom transaction submission client vs celestia-node client #4 (custom transaction submission client) — nonce management is tightly coupled with how we build and broadcast transactions

References

• Cosmos SDK sequence/nonce model: auth module BaseAccount.Sequence