Harden distribution withdraw address handling

[codchen]

Summary

• validate configured distribution withdraw recipients against bank recipient checks
• fall back to the delegator address when a stored withdraw recipient is no longer receivable
• add regression coverage for stale withdraw-recipient state

Tests

• go test ./sei-cosmos/x/distribution/keeper
• go test ./sei-cosmos/x/distribution/...
• go test ./sei-cosmos/x/bank/keeper

[cursor]

PR Summary

Medium Risk
Changes reward-withdraw address validation and lookup behavior, which can alter where validator/delegator rewards are sent if a previously-configured recipient becomes invalid. Logic is straightforward but touches distribution payout paths and depends on bankKeeper.CanSendTo.

Overview
Distribution withdraw recipients are hardened against non-receivable addresses. SetWithdrawAddr now rejects recipients failing bankKeeper.CanSendTo, and GetDelegatorWithdrawAddr now falls back to the delegator address when the stored withdraw address is blocked or no longer passes bank recipient checks.

This extends the distribution BankKeeper interface with CanSendTo and adds regression tests covering EVM address-mapping scenarios that make a previously-valid withdraw address become invalid (including ensuring AfterValidatorRemoved payouts don’t panic and still credit the delegator).

^{Reviewed by Cursor Bugbot for commit e4dc78b. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	May 21, 2026, 5:10 AM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.32%. Comparing base (823a78d) to head (e4dc78b).
⚠️ Report is 27 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3463      +/-   ##
==========================================
+ Coverage   59.29%   59.32%   +0.02%     
==========================================
  Files        2125     2125              
  Lines      175629   175636       +7     
==========================================
+ Hits       104144   104190      +46     
+ Misses      62404    62362      -42     
- Partials     9081     9084       +3     

Flag	Coverage Δ
sei-chain-pr	70.28% <100.00%> (?)
sei-db	70.41% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
sei-cosmos/x/bank/keeper/send.go	92.45% <ø> (ø)
sei-cosmos/x/distribution/keeper/keeper.go	87.17% <100.00%> (+0.69%)	⬆️
sei-cosmos/x/distribution/keeper/store.go	70.38% <100.00%> (+7.77%)	⬆️

... and 2 files with indirect coverage changes

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