Fixes #10115 - 10 : storage snapshot timing

[sagarkhandagre998]

PR description

Problem

The storage field in debug trace struct logs was being emitted on every opcode, not just storage-touching ones. The root cause was in DebugOperationTracer.captureStorage():

getUpdatedStorage()returns "all storage slots written so far in the transaction" — it accumulates across opcodes. So once anySSTORE` executed, every subsequent frame (ADD, PUSH, JUMP, etc.) included the full dirty-storage map. This diverges from geth and the execution-apis spec, as highlighted in the ethPandaOps trace comparison report.

Approach & Reasoning

The spec says: emit storage only for SLOAD and SSTORE, showing only the single slot touched by that operation.

For SSTORE this was straightforward — SStoreOperation already calls frame.storageWasUpdated(key, newValue) on success, which sets frame.getMaybeUpdatedStorage(). That's exactly the one slot we need. No extra tracking required.

For SLOAD it was trickier. SLoadOperation doesn't call storageWasUpdated (it's a read, not a write), so getMaybeUpdatedStorage() is always empty for it. Two pieces of data are needed: the slot key and the loaded value.

• The key sits at the top of the stack before execution (SLOAD pops it). So it must be captured in tracePreExecution() before the opcode runs — introducing the preExecutionStorageKey field.
• The loaded value is pushed to the top of the stack after execution, so frame.getStackItem(0) in tracePostExecution() gives it directly.

This approach deliberately avoids depending on options.traceStack() being enabled — the key is captured independently of stack tracing, so storage capture works correctly regardless of what other trace flags the caller set.

One edge case considered: if SLOAD halts (e.g. OOG), the value was never pushed, so the stack top would be wrong. This is guarded by checking operationResult.getHaltReason() == null before reading the stack — matching what geth does (no storage entry on a halted SLOAD).

Tests

All 21 tests in DebugOperationTracerTest pass, including the 3 new ones:

• shouldRecordStorageForSstoreWhenEnabled — verifies single-slot map with correct key/value
• shouldRecordStorageForSloadWhenEnabled — verifies key captured pre-execution, value captured post-execution
• shouldNotRecordStorageForNonStorageOpcodeWhenEnabled — verifies MUL (and any non-storage opcode) emits empty storage even when `traceStorage=true

Fixed Issue(s)

Fixes #10115

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• For database changes (e.g. KeyValueSegmentIdentifier) considered compatibility and performed forwards and backwards compatibility tests

Locally, you can run these tests to catch failures early:

• spotless: ./gradlew spotlessApply
• unit tests: ./gradlew build
• acceptance tests: ./gradlew acceptanceTest
• integration tests: ./gradlew integrationTest
• reference tests: ./gradlew ethereum:referenceTests:referenceTests
• hive tests: Engine or other RPCs modified?

[sagarkhandagre998]

@macfarla Kindly take a look at once.