fix(prover): Bind parentStateRoot to parentShnarf presage

[Tabaie]

This PR tightens the state root binding of the aggregated proof seen by L1.

Now the parent shnarf (to which the aggregation PI is already bound) is opened in the PI interconnection circuit and ensured to match the parent state root of the first execution proof. This requires no nontrivial change to the verifier contract, but it does involve updates to the coordinator as the prover backend now needs the parent shnarf pre-image.

It also removes the Koalabear migration state root fallback, which is no longer necessary.

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I am not well versed in the coordinator or the Kotlin language so we will probably need some hands-on involvement from the coordinator team.

[Copilot]

Pull request overview

This PR tightens the security binding between the aggregation proof and the previous (parent) L2 state root by opening the parent shnarf inside the PI interconnection circuit and enforcing that it matches the first execution proof’s parent state root. It also removes the previously flagged Koalabear migration fallback path by eliminating the related circuit logic and tests, and updates the coordinator to supply the required parent shnarf preimage components to the prover.

Changes:

• Extend aggregation inputs to include the parent shnarf preimage components (grandparent shnarf + snark hash + evaluation point/claim) and validate/open them in the PI interconnection circuit.
• Update coordinator aggregation flow to fetch the parent blob compression proof from storage (or an in-memory repository for backtesting) and pass its shnarf preimage to the prover request.
• Remove Koalabear migration fallback logic and the dedicated migration tests.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
prover/public-input/aggregation.go	Adds parent shnarf preimage fields to the aggregation request model; adjusts snark-type struct layout.
prover/circuits/pi-interconnection/test_utils/test_utils.go	Adds helper to fabricate consistent parent shnarf preimages and wires them into PI-interconnection test requests.
prover/circuits/pi-interconnection/koala_migration_test.go	Removes tests for the Koalabear migration fallback/selection mechanism.
prover/circuits/pi-interconnection/e2e_test.go	Updates E2E tests to include parent shnarf preimage inputs.
prover/circuits/pi-interconnection/circuit.go	Implements in-circuit opening of the parent shnarf and derives the initial state root from that opening; removes Koalabear fallback logic.
prover/circuits/pi-interconnection/assign.go	Recomputes and checks the parent shnarf digest from its preimage (mirrors in-circuit check) and removes Koalabear fallback plumbing.
prover/CHANGELOG.md	Adds unreleased changelog entry for the aggregation binding fix.
prover/backend/aggregation/request.go	Extends prover aggregation request schema to include parent shnarf preimage components.
prover/backend/aggregation/prove.go	Propagates the new preimage fields into the prover’s aggregation public input construction.
prover/backend/aggregation/craft.go	Carries the new preimage fields through collection/crafting of aggregation requests/responses.
coordinator/core/src/test/kotlin/linea/coordination/aggregation/ProofAggregationCoordinatorServiceTest.kt	Updates coordinator unit test to mock parent blob lookup and assert new shnarf-preimage fields are populated.
coordinator/core/src/main/kotlin/linea/coordination/aggregation/ProofAggregationCoordinatorService.kt	Fetches parent blob compression proof from BlobsRepository and injects the shnarf preimage into aggregation proof requests.
coordinator/core-interfaces/src/main/kotlin/linea/domain/Aggregation.kt	Extends ProofsToAggregate domain object with the parent shnarf preimage components.
coordinator/clients/prover-client/file-based-client/src/test/kotlin/linea/coordinator/clients/prover/ProverClientFactoryTest.kt	Updates test fixtures to include the new ProofsToAggregate fields.
coordinator/clients/prover-client/file-based-client/src/main/kotlin/linea/coordinator/clients/prover/FileBasedProofAggregationClientV2.kt	Extends aggregation request DTO to serialize grandparent shnarf + parent shnarf (snarkHash/x/y).
coordinator/CHANGELOG.md	Adds unreleased changelog entry for supplying parent shnarf preimage in aggregation requests.
coordinator/app/src/main/kotlin/linea/coordinator/app/conflationbacktesting/InMemoryBlobsRepository.kt	Adds an in-memory BlobsRepository implementation to support backtesting without Postgres blobs table.
coordinator/app/src/main/kotlin/linea/coordinator/app/conflationbacktesting/ConflationBacktestingApp.kt	Wires the new in-memory blobs repository into backtesting flow and populates it as blobs are proven.
coordinator/app/src/main/kotlin/linea/coordinator/app/conflation/ConflationApp.kt	Passes blobsRepository into the aggregation coordinator service so production flow can fetch parent compression proofs.

[codecov]

Codecov Report

❌ Patch coverage is 81.98198% with 20 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
.../aggregation/ProofAggregationCoordinatorService.kt	74.54%	14 Missing ⚠️
.../conflationbacktesting/ConflationBacktestingApp.kt	0.00%	3 Missing ⚠️
...p/conflationbacktesting/InMemoryBlobsRepository.kt	91.66%	0 Missing and 2 partials ⚠️
.../linea/coordinator/app/conflation/ConflationApp.kt	0.00%	1 Missing ⚠️

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