fix(wasmbinding): set top-level Metadata.Decimals in SetTokenMetadata translation

[danvaneijck]

fix(wasmbinding): set top-level Metadata.Decimals in SetTokenMetadata translation

Summary

Fixes #37.

The CosmWasm SetTokenMetadata wasm-binding translation built the bank Metadata struct without setting the top-level Decimals field, leaving it as the zero default. The bank precompile reads metadata.Decimals (not DenomUnits[i].Exponent) when serving decimals() to auto-deployed ERC20 wrappers — so adapter-wrapped denoms whose metadata was set via wasm bindings produce ERC20s that report decimals() == 0, blocking functional MTS registration for every CW20-adapter-wrapped denom (197 mainnet denoms today).

Change

Single-line addition to injective-chain/wasmbinding/message_plugin.go SetTokenMetadata translation, setting Metadata.Decimals = mt.Decimals so the precompile and the second DenomUnit.Exponent agree.

 Metadata: banktypes.Metadata{
     Base:    mt.Denom,
     Display: mt.Symbol,
     Name:    mt.Name,
     Symbol:  mt.Symbol,
+    Decimals: mt.Decimals,
     DenomUnits: []*banktypes.DenomUnit{ ... },
 },

Test plan

The injective-chain/wasmbinding package currently has no test infrastructure, so validation is via manual reproduction on a local testnet:

1. Deploy a CW20 contract with decimals = 18.
2. Deploy the CW20 Adapter (or use the standard mainnet one at inj14ej…).
3. Call RegisterCw20Contract then UpdateMetadata on the adapter for that CW20.
4. Query injectived q bank denom-metadata factory/<adapter>/<cw20> — decimals should now be 18 (was 0 before this fix).
5. Submit MsgCreateTokenPair for the denom; auto-deploy the wrapper.
6. Call decimals() on the resulting ERC20 via EVM RPC — should return 18.

Mainnet evidence of the bug (pre-fix), included for context:

• factory/inj14ej…/inj1300xcg9…87xm8 (SHROOM/shroomin): decimals=0, display-unit exponent=18 (after UpdateMetadata).
• factory/inj14ej…/inj1x997dy…zcnq (TRUINJ): same pattern.
• factory/inj178zy…/DRUGS (control — set via direct MsgSetDenomMetadata, prop 594): decimals=6 populated correctly, ERC20 at 0x7F073F52051eEF8512519ee7A627F8db1cD63303 reports decimals()=6 via EVM RPC.

Compatibility

• Existing affected denoms keep their current Decimals=0 until UpdateMetadata is re-run after the fix lands. The patch only affects future translations.
• tokenfactory.MsgServer.SetDenomMetadata validation: the existing check existingMetadata.Decimals != 0 && existingMetadata.Decimals != msg.Metadata.Decimals still works — first-time set passes (existing=0), and re-runs with matching decimals pass too.
• Metadata.Validate(): standard SDK validation does not restrict the extended Decimals field.

Notes

The CW20 Adapter contract (inj14ej…) is immutable (wasmd admin: ""), and its denoms cannot be reassigned to a different admin contract — so a chain-level fix is the only path to unblock MTS registration for every adapter-wrapped denom. Happy to add a regression test in this PR if the maintainers would like to bootstrap a wasmbinding_test.go for this package; defaulted to no test to keep the patch minimal.

[gorgos]

LGTM, will add to upstream