feat(services): 3/n - preview custom SEP-41 token state changes in simulateStateChanges

[JiahuiWho]

What

Extends simulateStateChanges to cover custom SEP-41 tokens by mirroring what live ingestion does after the indexer pass, with persistence removed:

1. ProtocolProcessor.StagedStateChanges() (new interface method): reads the processor's computed state changes without persisting them to the DB.
2. Simulation service: after the main indexer runs, we take the contract events it collected, ask the database which of those contracts are known SEP-41 tokens, run the SEP-41 processor over the events, and add its state changes to the preview.
3. Wiring: the serve binary now imports sep41 so the processor registers itself at startup, and the simulation service gets Models so it can do the classification lookup.

Why

Previously the simulation only ran the main indexer, skips non-SAC token events deliberately because sep41.Processor owns them.

Known limitations

N/A

Issue that this PR addresses

#618

PR Structure

• It is not possible to break this PR down into smaller PRs.
• This PR does not mix refactoring changes with feature changes.
• This PR's title starts with name of package that is most changed in the PR, or all if the changes are broad or impact many packages.

Thoroughness

• This PR adds tests for the new functionality or fixes.
• All updated queries have been tested (refer to this check if the data set returned by the updated query is expected to be same as the original one).

Release

• This is not a breaking change.
• This is ready to be tested in development.
• The new functionality is gated with a feature flag if this is not ready for production.

[Copilot]

Pull request overview

Extends transaction simulation to preview state changes for custom SEP-41 tokens without persistence.

Changes:

• Runs registered protocol processors during simulation.
• Exposes staged SEP-41 state changes.
• Wires models and SEP-41 registration into serving.
• Adds service and GraphQL test coverage.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Review
internal/services/transaction_simulation.go	Requires same-ledger contract classification and explicit processor resets before processing.
internal/services/transaction_simulation_test.go	Updates constructor calls.
internal/services/transaction_simulation_sep41_test.go	Adds end-to-end SEP-41 simulation tests.
internal/services/sep41/processor.go	Exposes staged changes; nit: restore the Reset documentation placement.
internal/services/protocol_processor.go	Extends the processor interface.
internal/services/protocol_migrate_test.go	Updates the test processor.
internal/services/processor_registry_test.go	Updates registry stubs.
internal/services/mocks.go	Extends the processor mock.
internal/services/ingest_test.go	Updates the ingestion test processor.
internal/serve/serve.go	Registers SEP-41 and injects models.
internal/serve/graphql/utils_test.go	Covers the simulation failure code.
internal/serve/graphql/resolvers/simulation_test.go	Tests simulated-state conversion.
internal/serve/graphql/resolvers/queries_resolvers_test.go	Tests simulation error mapping.

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[JiahuiWho]

@copilot resolve the merge conflicts in this pull request

[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated no new comments.

Suppressed comments (1)

internal/services/transaction_simulation.go:62

• This comment says models is used only for protocol_contracts, but this path also queries ProtocolWasms to classify same-transaction bindings (line 453). Mentioning both lookups avoids misleading callers that provide partial model aggregates.

// NewTransactionSimulationService builds the simulation service. models is used
// only for the read-only protocol_contracts lookup that routes contract events
// to the registered protocol processors (SEP-41); a nil models skips protocol
// processing, so previews then cover native/SAC tokens only.

[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated no new comments.

[aditya1702]

Why are we doing classification when generating the simulated state changes? Shouldn't that happen only in live ingestion?

[JiahuiWho]

Because ingestion will classify this contract when the transaction lands, the preview must classify it too, or it would miss rows history will show. It's in-memory and read-only, nothing is persisted.