Missing Debug / Trace API Support in Frontier (stable2503)

[havannaa]

We are running a Substrate-based EVM chain using Frontier stable2503. During integration testing, we observed that internal transaction tracing is not available, as Frontier does not expose debug_traceTransaction or other Trace API methods required by EVM explorers and debugging tools.

This aligns with the previously reported issue:
#703

Before building our own implementation, we would like clarification on whether Frontier currently supports any Debug / Trace API modules in recent versions, or if these APIs remain unimplemented and must be added externally (as done by Moonbeam).

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Environment

• Frontier version: stable2503 (fp-*, fc-*, and EVM pallets all pinned to this branch)
• Node type: Substrate + Frontier EVM runtime

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Observed Behavior

• debug_traceTransaction and trace_transaction return method not found.
• Internal transfer data cannot be retrieved since the RPC layer does not emit execution traces.
• Local Geth/Anvil nodes do return full trace data, confirming the Web3 implementation is correct.

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Expected Behavior

Frontier should expose APIs compatible with:

• debug_traceTransaction
• debug_traceCall
• trace_transaction
• trace_block
• trace_call

…or provide an equivalent mechanism for generating and returning internal transaction traces from within the node.

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Questions for Maintainers

1. Does Frontier stable2503 include any implementation of the Debug / Trace API?
   Current documentation suggests it may still be missing, but confirmation would help us plan.

2. If not implemented, is there a roadmap or recommended approach for adding Trace API support to Frontier?

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Request

Please confirm whether the Debug / Trace API is implemented in any active branch or release, and whether contributions in this area would be welcomed.

Thank you.