The Final Piece: Wiring the Bench Tool for Multi-Proof Testing in cuzk's Phase 1

A Small Message with Outsize Significance

In the sprawling, multi-session effort to build the cuzk proving daemon—a pipelined SNARK proving engine for Filecoin's storage proof requirements—message [msg 325] appears, at first glance, almost trivial. It reads in its entirety:

Now update the main command handlers and the do_prove function: [edit] /home/theuser/curio/extern/cuzk/cuzk-bench/src/main.rs Edit applied successfully.

Fourteen words. A single file edit. No reasoning block, no analysis, no fanfare. Yet this message represents the culmination of an extraordinarily deep implementation phase that spanned dozens of earlier messages, hundreds of lines of code across six source files, and hours of meticulous research into the Filecoin proof system's FFI layer, enum mappings, and API signatures. Understanding why this message exists—and what it accomplishes—requires tracing the entire arc of Phase 1 of the cuzk project.

The Context: Building a Universal Proving Engine

The cuzk daemon began as a Phase 0 prototype that could handle only one proof type: PoRep (Proof of Replication) C2, the Groth16 proof generation step for Filecoin's sector sealing process. Phase 0 validated the core architecture—a gRPC service backed by a priority-scheduled worker pool—and demonstrated a 20.5% speedup from SRS (Structured Reference String) parameter residency in GPU memory.

Phase 1, the subject of this message's surrounding context, aimed to expand cuzk from a PoRep-only tool into a universal proving daemon capable of handling all four Filecoin proof types:

1. PoRep C2 (already implemented) — Groth16 proof for sector sealing
2. WinningPoSt — Proof of SpaceTime for winning block rewards
3. WindowPoSt — Proof of SpaceTime for proving sector storage over time
4. SnapDeals — Proof for updating sealed sectors with new data Each of these proof types has different inputs, different serialization formats, and different FFI function signatures. The challenge was to design a unified gRPC API and internal representation that could accommodate all four without compromising the performance characteristics that made Phase 0 successful.

The Research-Driven Approach

What makes message [msg 325] meaningful is the invisible architecture of decisions that preceded it. In the messages leading up to this point (see [msg 289] through [msg 324]), the assistant engaged in a systematic, research-driven implementation process that reveals a clear methodology.

The assistant began by reading every relevant source file in the cuzk workspace: the protobuf definition (proving.proto), the core types (types.rs), the service layer (service.rs), the engine (engine.rs), the prover module (prover.rs), and the bench tool (main.rs). This established a complete mental model of the existing codebase before any changes were made.

Then came the critical research phase. The assistant explored the filecoin-proofs-api crate to understand the exact function signatures for each proof type. This revealed several crucial details:

• WinningPoSt requires multiple vanilla proofs (one per sector) and produces a single PartitionSnarkProof
• WindowPoSt similarly takes multiple vanilla proofs and returns a PartitionSnarkProof
• SnapDeals (via generate_empty_sector_update_proof_with_vanilla) requires three commitment CIDs (comm_r_old, comm_d, comm_r_new) and returns an EmptySectorUpdateProof newtype around Vec<u8> The assistant also traced the FFI enum mappings from Go's abi.RegisteredPoStProof through the C #[repr(i32)] enum in filecoin-ffi to the Rust filecoin-proofs-api equivalents. This was essential because the gRPC API receives numeric proof-type identifiers from Curio's Go layer, and those numbers must be correctly mapped to the Rust enum variants. The assistant discovered, for instance, that the FFI enum uses auto-incrementing i32 discriminants starting from 0, and that the V1_1 variants in the Go/FFI layer map to V1_2 in the Rust API.

The Implementation Cascade

With this research complete, the assistant executed a carefully ordered cascade of edits:

1. Protobuf definition — Added repeated bytes vanilla_proofs to support multi-proof requests, renamed SnapDeals commitment fields to match the API (comm_r_old, comm_d, comm_r_new)
2. Types.rs — Added the vanilla_proofs: Vec<Vec<u8>> field to ProofRequest and updated the SnapDeals field names
3. Prover.rs — Replaced stub functions with real implementations for prove_winning_post(), prove_window_post(), and prove_snap_deals(), each with proper enum conversion via manual match statements
4. Engine.rs — Updated the dispatch logic to pass the new fields through to the prover
5. Service.rs — Updated the gRPC service to populate the new vanilla_proofs field and commitment fields from the protobuf request
6. Bench tool — Updated to support all proof types with proper input loading and field population Message [msg 325] is the final step in this cascade: updating the bench tool's main command handlers and do_prove function to wire everything together for testing.

Why the Bench Tool Matters

The bench tool (cuzk-bench) is not a mere convenience utility—it is the primary validation mechanism for the entire proving pipeline. Without it, there is no way to verify that the new proof types work end-to-end without deploying the full Curio stack. The bench tool simulates what Curio's Go layer would send over gRPC, making it the critical integration test harness.

The do_prove function is the heart of this tool. It constructs a SubmitProofRequest protobuf message with all the required fields and sends it to the daemon. For Phase 1, this function needed to:

• Accept flags for proof type (--winning-post, --window-post, --snap-deals)
• Load the appropriate input files (vanilla proofs, randomness seeds, commitment CIDs)
• Populate the vanilla_proofs repeated field for multi-proof types
• Set the correct registered_proof numeric value
• Handle the SnapDeals-specific commitment fields The edit referenced in [msg 325] completed this wiring, making it possible to run commands like:

cuzk-bench single --winning-post --sector-size 32GiB
cuzk-bench batch --window-post --count 10 --sector-size 32GiB
cuzk-bench single --snap-deals --sector-size 32GiB

Assumptions and Design Decisions

The implementation embodied several key assumptions. First, the assistant assumed that the bench tool should mirror the gRPC API exactly—that is, it should construct protobuf messages directly rather than wrapping them in a higher-level abstraction. This keeps the bench tool transparent: what you send is what the daemon receives, making debugging easier.

Second, the assistant assumed that the registered_proof numeric values from the Go abi package would be passed directly through the gRPC uint64 field and matched in Rust. This required the manual match statements in prover.rs that convert u64 → FFI enum → Rust API enum. The correctness of this mapping was verified by cross-referencing the C header constants, the FFI #[repr(i32)] enum, and the Rust API's From<i32> implementations.

Third, the assistant made an architectural decision to defer GPU affinity-based scheduling to Phase 2. The current process-global GROTH_PARAM_MEMORY_CACHE makes per-GPU SRS tracking unnecessary for Phase 1, so the shared priority queue with BinaryHeap was retained as the correct design. This decision appears in the post-commit review but informed the implementation: the bench tool and engine did not need to track GPU affinity yet.

The Knowledge Flow

Message [msg 325] is a terminal node in a knowledge pipeline. The input knowledge required to write it included:

• The complete structure of the cuzk workspace (six crates, their interdependencies)
• The filecoin-proofs-api function signatures for all four proof types
• The FFI enum mappings from Go through C to Rust
• The protobuf serialization format for repeated bytes fields
• The existing bench tool architecture and its do_prove function The output knowledge created by this message is more subtle but equally important. The completed bench tool now serves as: 1. A validation harness — Proving that all four proof types can be dispatched through the unified gRPC API 2. A performance measurement tool — The batch command can now measure throughput for any proof type 3. A regression test — Future changes to the API or prover logic can be tested against known-working bench commands 4. A reference implementation — Developers integrating cuzk into Curio can study the bench tool to understand the exact protobuf format expected

The Thinking Process

While message [msg 325] itself contains no explicit reasoning, the thinking process is visible in the surrounding message sequence. The assistant followed a pattern that recurs throughout the cuzk project:

1. Survey — Read all relevant source files to establish baseline understanding
2. Research — Explore external APIs and FFI layers to gather precise signatures and mappings
3. Plan — Create a structured todo list with ordered phases
4. Implement bottom-up — Start with the lowest layer (protobuf), then types, then prover logic, then engine dispatch, then service mapping, and finally the tooling
5. Verify — Check compilation, run unit tests, and commit This bottom-up implementation order is notable. By starting with the protobuf definition and working upward through the layers, each edit could be verified against the previous layer's interface. The protobuf change defines the contract; types.rs implements that contract in Rust; prover.rs consumes the types; engine.rs dispatches to the prover; service.rs maps gRPC to engine calls; and the bench tool exercises the whole chain. Message [msg 325] is the final link in this chain—the last piece that makes the entire pipeline testable.

Conclusion

Message [msg 325] is a study in how small, seemingly trivial commits can represent the completion of substantial intellectual work. The fourteen-word edit to cuzk-bench/src/main.rs is the capstone on an implementation phase that required deep research into Filecoin's proof system architecture, careful design of a unified gRPC API, and methodical implementation across six files. It transforms cuzk from a PoRep-only prototype into a universal proving daemon capable of handling all four Filecoin proof types, setting the stage for Phase 2's GPU affinity scheduling and the eventual gen-vanilla command for end-to-end testing without external dependencies.

The message also exemplifies a key principle of systems engineering: the testing and validation tooling is not an afterthought but an integral part of the architecture. By ensuring the bench tool could exercise every proof type, the assistant created not just a daemon but a complete, testable system—one that could be extended, measured, and debugged with confidence.