Recover expired IBC client 07-tendermint-1808 (Osmosis <> Carbon)

Proposal Discussion
1

Summary

The IBC client 07-tendermint-1808 on Osmosis, which tracks Carbon (carbon-1), has expired. This proposal replaces its state with that of the active substitute client 07-tendermint-3767 using MsgRecoverClient.

Background

  • Osmosis side: client 07-tendermint-1808, connection-1412, transfer/channel-188 and transfer/channel-189.
  • Carbon side: client 07-tendermint-3, transfer/channel-0 and transfer/channel-1. Carbon governance already recovered this client (proposal 432, passed 3 Nov 2026).
  • Last update: 25 Sep 2026 10:40 UTC, with a 14-day trusting period. The client expired while Carbon was halted. Carbon resumed on 29 Oct 2026.

What it does

  • Lets relayers finish the packets stuck since the expiry, so timed-out transfers can refund their senders on Osmosis.
  • Keeps the existing connections and channels. No new channels or denoms.
  • Moves no funds and changes no parameters. It only affects this one client.

The substitute client

  • Created in tx B8C18274461C676201C4B8028CAA7981BDF98253BAD2C7BBF04FCBF5EE9B9846, Osmosis height 74065632.
  • Differs from the expired client only in latest height. Chain id, trust level (1/3), trusting period (14 days), unbonding period (30 days), clock drift (20s), proof specs and upgrade path all match.
  • Its stored state matches carbon-1 block 100606708 (hash F7867B95B9C2DDE2AD05FD11A70AE6468E926764170341F22BC38A122A0742A9), checked against the header hash and validator signatures.

How to confirm this is the real Carbon chain

  • The chain registry lists this path: 07-tendermint-1808, connection-1412 and channel-188 (_IBC/carbon-osmosis.json in cosmos/chain-registry). It also lists tm-api.carbon.network as a Carbon RPC.
  • The last state 07-tendermint-1808 stored matches carbon-1 block 100258045 on that RPC: root, next validators hash and time.
  • Validators holding 88.28% of the voting power 07-tendermint-1808 last trusted signed block 100606708, the block the substitute stores. Their keys hash to the next validators hash already stored on Osmosis. A normal client update needs more than 1/3.

To check:

osmosisd q ibc client status 07-tendermint-1808
osmosisd q ibc client state 07-tendermint-1808
osmosisd q ibc client state 07-tendermint-3767

This is on chain as proposal #1060, with the normal 5-day vote, ending 9 Nov 2026 09:48 UTC. Questions welcome here.

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