The 32 GiB Parameter Gap: A Case Study in Environmental Dependency Resolution

The Message

Only 4 .params files exist, and none are for 32G sectors (8-8-2 pattern). The 32G params need to be properly fetched. Let me also check if they ended up in ~/scrot/data/zk/params/:

`` [bash] ls ~/scrot/data/zk/params/ 2>/dev/null | head -20 || echo "not there either" v28-empty-sector-update-merkletree-poseidon_hasher-8-0-0-61fa69f38b9cc771ba27b670124714b4ea77fbeae05e377fb859c4a43b73a30c.vk v28-empty-sector-update-merkletree-poseidon_hasher-8-0-0-92180959e1918d26350b8e6cfe217bbdd0a2d8de51ebec269078b364b715ad63.vk v28-empty-sector-update-merkletree-poseidon_hasher-8-0-0-fb9e095bebdd77511c0269b967b4d87ba8b8a525edaa0e165de23ba454510194.vk v28-empty-sector-update-merkletree-poseidon_hasher-8-8-0-3b7f44a9362e3985369454947bc94022e118211e49fd672d52bec1cbfd599d18.par... ``

At first glance, this message appears to be a routine diagnostic check—a developer listing files in a directory to verify whether a download succeeded. But in the context of building a production-grade SNARK proving engine, this moment represents a critical inflection point. The entire Phase 0 implementation of the cuzk pipelined proving daemon—six Rust crates, a gRPC API, a priority scheduler, and the full proof submission pipeline—had been built, compiled, and validated. The request/response cycle worked. The error handling propagated correctly. The Prometheus metrics fired. Everything was in place except for one thing: the 32 GiB Groth16 parameters that make the cryptographic proof generation actually work.

This message is the moment where the abstraction of "software architecture" collides with the concrete reality of "environmental dependencies." It is the story of a team that built a beautifully engineered machine, only to discover they needed a 45-gigabyte key to turn it on.

The Context: Building a Pipelined SNARK Proving Engine

To understand why this message matters, one must understand what came before it. The cuzk project was born from an exhaustive investigation of the SUPRASEAL_C2 Groth16 proof generation pipeline for Filecoin's Proof-of-Replication (PoRep) protocol. The existing pipeline had been analyzed down to its CUDA kernels, revealing a peak memory footprint of approximately 200 GiB and nine structural bottlenecks. Five optimization proposals had been developed, ranging from Sequential Partition Synthesis to a Persistent Prover Daemon. The team had designed a new architecture: a pipelined SNARK proving daemon that would manage proof requests, prioritize them, batch them, and eventually support multiple proof types with efficient memory management.

Phase 0 was the foundation. The assistant had created the entire extern/cuzk/ Rust workspace from scratch, comprising six crates: cuzk-proto for the gRPC protocol definitions, cuzk-core for the engine architecture and priority scheduler, cuzk-server for the gRPC server, cuzk-daemon for the long-running daemon binary, cuzk-bench for benchmarking and client testing, and cuzk-ffi for FFI bindings. The protobuf API defined proof submission and daemon management RPCs. The core engine implemented a priority scheduler. The prover module was wired to real filecoin-proofs-api calls for seal_commit_phase2—the actual C2 proof generation function.

The team had fought through build system incompatibilities: Rust edition mismatches, missing dependencies, gRPC message size limits that needed to be raised to handle ~50 MB PoRep C1 inputs. They had pinned a rust-toolchain.toml to ensure reproducible builds. They had validated the end-to-end gRPC pipeline: the daemon started, cuzk-bench status queried it correctly, and a full PoRep C2 proof submission was attempted. The proof itself failed—but the error was cleanly propagated back to the client, and the daemon's Prometheus metrics accurately recorded the failure (proofs failed: 1). The core communication path was proven.

All that remained was the parameters. And that is where this message enters the story.

The Diagnostic Trail: Three Messages of Discovery

Messages 185, 186, and 187 form the investigative arc that leads to message 188. In message 185, the assistant diagnosed why curio fetch-params 32GiB had failed: the tool had a path resolution bug. When run from the ~/scrot/ directory, it interpreted the target path /data/zk/params/ as a relative path, placing files at ~/scrot//data/zk/params/ instead. The assistant verified that /data/zk/ existed and that /data/zk/params/ was an empty directory.

In message 186, the assistant confirmed the emptiness: ls -la /data/zk/params/ returned nothing. The directory had been created (likely by the failed fetch attempt) but contained zero files.

In message 187, the assistant considered a shortcut. Rather than re-downloading ~53 GiB of parameters, could the existing parameters in /var/tmp/filecoin-proof-parameters/ be symlinked? This is a common tactic in development environments—avoid redundant downloads by pointing to files that are already present. The assistant ran a grep to check: only 4 .params files existed, and none matched the 8-8-2 pattern that identifies 32 GiB sector parameters. The shortcut was not viable.

The Discovery in Message 188

Message 188 opens with a summary judgment: "Only 4 .params files exist, and none are for 32G sectors (8-8-2 pattern). The 32G params need to be properly fetched." This is the conclusion of the diagnostic trail. The assistant then pivots to check the alternative location—the botched download destination at ~/scrot/data/zk/params/.

The output of ls reveals files, but they are not the needed parameters. The listing shows four .vk (verification key) files for "empty-sector-update" operations with an 8-0-0 topology, and one truncated entry showing a .par... file for an 8-8-0 topology. The 8-8-2 pattern—which corresponds to the 32 GiB sector parameters required for C2 proof generation—is absent.

This is a moment of grounded reality. The team has built a sophisticated proving engine, but it cannot generate a single proof without these parameters. The .vk files are verification keys used by the Filecoin protocol for verifying proofs, not the Groth16 proving parameters (which include the SRS—Structured Reference String—and other elliptic curve data) needed to generate proofs. The .par... file is a truncated output, but even if complete, the 8-8-0 topology does not match the required 8-8-2.

The message ends without a resolution. The assistant has identified the problem but not yet solved it. The next step would be to either re-run fetch-params from the correct directory, copy the files from the wrong location, or download them from an alternative source.

Assumptions and Mistakes

Several assumptions underpin this message, and some prove to be incorrect.

Assumption 1: The parameters would be in the default location. The assistant checked /var/tmp/filecoin-proof-parameters/ expecting to find the 32 GiB parameters, perhaps from a previous installation or from the curio tool's default behavior. This assumption was reasonable—the Filecoin proof parameter system conventionally stores files in that directory—but it was wrong. Only 4 parameter files existed, none matching the required pattern.

Assumption 2: The botched download might have placed the right files in the wrong directory. The assistant checked ~/scrot/data/zk/params/ hoping that despite the path resolution bug, the correct files had been downloaded. This was partially correct—files were there—but they were the wrong files. The curio fetch-params 32GiB command may have downloaded verification keys and partial parameters for other sector sizes, but the critical 32 GiB stacked-proof-of-replication parameter file was not among them.

Assumption 3: The 8-8-2 pattern is the correct identifier for 32 GiB sector parameters. This is a domain-specific assumption about the Filecoin proof parameter naming convention. In Filecoin's proof system, parameters are named with a topology pattern that encodes the sector size and proof structure. The 8-8-2 pattern corresponds to the 32 GiB sector configuration (8 nodes, 8 layers, 2 partitions). The assistant's understanding of this convention appears to be correct.

The mistake in the tooling: The underlying mistake that necessitated this entire diagnostic chain was a path resolution bug in curio fetch-params. When given an absolute path like /data/zk/params/, the tool should have used it as an absolute path. Instead, it treated it as relative to the current working directory, creating a nested path under ~/scrot/. This is a classic software bug—a failure to properly handle absolute versus relative path resolution—and it cost the team time and diagnostic effort.

Input Knowledge Required

To fully understand this message, one needs several layers of domain knowledge:

Filecoin proof system architecture: Understanding that PoRep (Proof-of-Replication) proofs require large structured reference string (SRS) parameters, typically stored as files on disk, and that these parameters are identified by topology patterns like 8-8-2 and 8-8-0. The numbers encode the Merkle tree structure: the number of nodes, the number of layers, and the number of partitions in the proof.

Groth16 proving pipeline: Knowing that Groth16 proof generation requires both the circuit description and the proving parameters (which include the SRS and other curve-specific data). Without these parameters, the elliptic curve operations (multi-scalar multiplication, number-theoretic transforms) cannot proceed.

The curio tool ecosystem: Understanding that curio is the Filecoin storage provider stack, and curio fetch-params is the command that downloads the necessary proof parameters. The tool has a known path resolution behavior that can be buggy in certain environments.

The cuzk project architecture: Knowing that Phase 0 of the cuzk proving daemon wires directly to filecoin-proofs-api's seal_commit_phase2 function, which internally loads these parameters. The daemon cannot generate proofs without them.

Linux file system conventions: Understanding that /var/tmp/filecoin-proof-parameters/ is the conventional location for Filecoin proof parameters, and that /data/zk/params/ is a custom location used by this particular deployment.

Output Knowledge Created

This message produces several valuable pieces of knowledge:

The 32 GiB parameters are definitively missing. This is the primary finding. The team now knows that no amount of symlink trickery or directory shuffling will make the existing parameters work. A fresh download is required.

The botched download placed verification keys, not proving parameters. The files in ~/scrot/data/zk/params/ are .vk files (verification keys) for empty-sector-update operations. These are used by the Filecoin protocol for verifying proofs on-chain, not for generating them. The team now knows that even the partial download did not produce the needed proving parameters.

The 8-8-0 topology is present but 8-8-2 is absent. This confirms that the existing parameter set supports some proof operations (likely smaller sector sizes or different proof types) but not the 32 GiB C2 proof that cuzk needs to generate.

A fresh fetch-params is the only path forward. The assistant's conclusion—"The 32G params need to be properly fetched"—is the actionable output. The team must either re-run the fetch from the correct directory or manually download the parameters from an alternative source.

The Thinking Process

The assistant's reasoning in this message follows a clear diagnostic pattern:

State the finding: "Only 4 .params files exist, and none are for 32G sectors." This is a concise summary of the discovery from message 187.
Draw the conclusion: "The 32G params need to be properly fetched." This is the logical inference—if the parameters aren't in the default location and aren't in the botched download location, they must be obtained anew.
Formulate the next hypothesis: "Let me also check if they ended up in ~/scrot/data/zk/params/." Despite the conclusion that a fresh fetch is needed, the assistant does not prematurely commit. It checks the alternative location because there is a chance—however slim—that the correct files were downloaded to the wrong path. This is good diagnostic discipline: exhaust all possibilities before declaring a definitive course of action.
Execute the check: The ls command lists the contents of the alternative directory, piped through head -20 to avoid flooding the output (parameter directories can contain dozens of files). The 2>/dev/null || echo "not there either" handles the case where the directory does not exist at all.
Interpret the results: The output shows .vk files and a truncated .par... entry. The assistant does not need to comment further—the absence of any file matching the 8-8-2 pattern is self-evident. The message ends, leaving the reader (and the user) to infer the next step. The thinking is methodical, grounded, and conservative. The assistant does not jump to conclusions, does not propose speculative solutions, and does not waste time on dead ends. It follows the evidence where it leads, and when the evidence is clear, it states the conclusion plainly.

Broader Significance

This message, for all its brevity, illustrates a fundamental truth about building production systems: the hardest problems are often not in the code but in the environment. The cuzk team had solved every software engineering challenge—Rust edition compatibility, gRPC message size limits, crate dependency resolution, priority scheduling, error propagation, metrics instrumentation. But none of that mattered without a 45 GiB file sitting in the right directory.

The parameter dependency is also a reminder that zero-knowledge proof systems are not purely algorithmic—they are also data-intensive. The Groth16 proving parameters for Filecoin's 32 GiB sectors are enormous because they encode the structured reference string for circuits with millions of constraints. Managing these parameters—downloading them, storing them, loading them into GPU memory—is a significant operational challenge. The cuzk project's Proposal 2 (Persistent Prover Daemon) directly addresses this by keeping the SRS loaded in memory across proof requests, eliminating the repeated loading overhead. But even that proposal assumes the parameters exist on disk somewhere.

In a sense, this message validates the entire Phase 0 effort. The team built a daemon that correctly identifies when parameters are missing and propagates the error. The proof submission failed, but it failed correctly—the error was not a crash, not a hang, not a silent corruption, but a clean, reportable failure. The metrics recorded it. The client received it. The system was honest about its limitations.

Conclusion

Message 188 is the moment when a software engineering project meets operational reality. The cuzk proving daemon is architecturally complete—it can accept requests, schedule them, invoke the proving library, and return results. But it cannot prove anything until the 32 GiB Groth16 parameters are in place. The assistant's methodical diagnostic work—checking default locations, alternative locations, and symlink possibilities—demonstrates a disciplined approach to environmental dependency resolution. The finding is definitive: the parameters are missing, a fresh fetch is required, and no amount of software engineering can substitute for the data itself.

The next step is straightforward: run curio fetch-params 32GiB from the correct directory, or copy the files that were downloaded to the wrong path. But the deeper lesson endures: in the world of zero-knowledge proofs, the boundary between "code" and "data" is porous, and both must be present for the system to function. The cuzk daemon is ready. Now it needs its keys.