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Moonwell redeem fails on Base Sepolia and uses 18 decimals for cbBTC

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Since Oct 20, 2026.

  • #1579 by @sebxt — open

Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
85/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
typescript
Domain
backend

Research direction

Start in typescript/agentkit/src/action-providers/moonwell/moonwellActionProvider.ts and trace how redeem selects the network-specific address map and resolves underlying token decimals. Then read typescript/agentkit/src/action-providers/moonwell/constants.ts for the cbBTC and USDBC decimal entries. Update the mappings so redeem works on both networks and cbBTC mint and redeem use 8 decimals; verify the repro amounts encode correctly.

Written by the indexing model from the issue text.

Description

What happens

  1. On Base Sepolia, MoonwellActionProvider.redeem always returns Error: Unsupported token address <mToken>. The redeem path picks the right address map for the network when validating the mToken, but then looks up the underlying decimals with the mainnet map:

    const decimals = MTOKENS_UNDERLYING_DECIMALS[MOONWELL_BASE_ADDRESSES[args.mTokenAddress]];

    Sepolia mToken addresses are not in MOONWELL_BASE_ADDRESSES, so decimals is undefined. MOONWELL_USDBC is also missing from MTOKENS_UNDERLYING_DECIMALS.

  2. MTOKENS_UNDERLYING_DECIMALS.MOONWELL_cbBTC is 18, but cbBTC (0xcbB7C0000aB88B473b1f5aFd9ef808440eed33Bf) has 8 decimals. Redeeming 0.5 cbBTC encodes redeemUnderlying(500000000000000000), which is 5,000,000,000 cbBTC, instead of redeemUnderlying(50000000). The transaction reverts.

  3. TOKEN_DECIMALS has no entry for cbBTC, so mint into the Moonwell cbBTC market returns Error: Unsupported token address 0xcbB7C0000aB88B473b1f5aFd9ef808440eed33Bf.

What should happen

Redeem works on both supported networks and uses the underlying token's real decimals. cbBTC can be supplied and redeemed with 8 decimals.

Minimal repro

// wallet on base-sepolia
await moonwell.redeem(wallet, {
  mTokenAddress: "0x876852425331a113d8E432eFFB3aC5BEf38f033a", // Sepolia mUSDBC
  assets: "1.5",
});
// => "Error: Unsupported token address 0x876852425331a113d8E432eFFB3aC5BEf38f033a. ..."

// wallet on base-mainnet
await moonwell.redeem(wallet, {
  mTokenAddress: "0xF877ACaFA28c19b96727966690b2f44d35aD5976", // Moonwell cbBTC
  assets: "0.5",
});
// sends redeemUnderlying(500000000000000000) instead of redeemUnderlying(50000000)

Onchain check of the underlying tokens (underlying() then decimals()):

Base Sepolia 0x876852425331a113d8E432eFFB3aC5BEf38f033a -> USDBC 6
Base         0xF877ACaFA28c19b96727966690b2f44d35aD5976 -> cbBTC 8

Root cause

typescript/agentkit/src/action-providers/moonwell/moonwellActionProvider.ts uses MOONWELL_BASE_ADDRESSES instead of the network specific networkObject when resolving decimals in redeem, and typescript/agentkit/src/action-providers/moonwell/constants.ts has the wrong decimals for cbBTC, no entry for MOONWELL_USDBC, and no cbBTC entry in TOKEN_DECIMALS.

Dominant language
TypeScript
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Getting set up

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

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