The Anatomy of a Single Grep: How One Bash Command Revealed the Integration Surface for Remote GPU Proving

Message Overview

The subject message is deceptively simple — a single grep command executed in a coding session:

[assistant] [bash] grep -E "ffi\." ./tasks/seal/task_synth_proofs.go
	sc  *ffi.SealCalls
func NewSyntheticProofTask(sp *SealPoller, db *harmonydb.DB, sc *ffi.SealCalls, maxSynths int) *SyntheticProofTask {
func (s *SyntheticProofTask) taskToSector(id harmonytask.TaskID) (ffi.SectorRef, error) {
	var refs []ffi.SectorRef
		return ffi.SectorRef{}, xerrors.Errorf("getting sector ref: %w", err)
		return ffi.SectorRef{}, xerrors.Errorf("expected 1 sector ref, got %d", len(refs))

On its surface, this is merely a developer searching for every reference to the ffi package within a single Go source file. But within the broader context of the session — a multi-week effort to build a remote GPU proving daemon called cuzk and integrate it into Filecoin's Curio storage mining orchestrator — this message represents a critical moment of architectural discovery. It is the point at which the assistant transitions from high-level planning to concrete implementation, using code exploration to identify every touchpoint that must be modified to wire a new dependency through an existing task lifecycle.

Context: The cuzk Integration Effort

To understand why this grep command matters, one must understand the larger project. The cuzk daemon is a standalone GPU proving service that offloads the computationally expensive Groth16 SNARK proof generation from Curio's local workers to a remote process. Curio, Filecoin's storage mining orchestrator, manages a complex pipeline of tasks: sector sealing (PoRep), SnapDeals replica updates, WindowPoSt, WinningPoSt, and proofshare. Each of these tasks currently performs SNARK computation locally, requiring direct access to high-end GPUs and consuming enormous memory (up to ~200 GiB for a single proof).

The architectural vision, established over the preceding segments of this session, was to keep cuzk as an independent process with its own gRPC API and resource management, while having Curio's task scheduler delegate SNARK computation to it. The key design decisions included:

Why This Message Was Written: The Reasoning and Motivation

The assistant had just finished examining task_porep.go in the previous message ([msg 3339]), where it discovered that PoRepTask holds a reference to *ffi.SealCalls — the existing local FFI interface for proof generation. The natural next question was: does SyntheticProofTask (in task_synth_proofs.go) follow the same pattern? If so, the integration strategy would be consistent across task types: add a cuzkClient field alongside the existing sc *ffi.SealCalls field, modify the constructor, and update the Do() method.

The assistant's reasoning, visible in the agent reasoning blocks of the preceding messages, shows a systematic exploration strategy. It had already:

  1. Identified the task files: task_porep.go, task_synth_proofs.go, task_prove.go (SnapDeals), winning_task.go, compute_task.go (WindowPoSt)
  2. Discovered the CanAccept mechanism in the harmony task framework
  3. Located the cuzk protobuf definitions in extern/cuzk/cuzk-proto/proto/cuzk
  4. Confirmed that ffi.SealCalls is the central abstraction for local proof generation The grep command in message 3340 is the logical next step: a targeted probe to verify the hypothesis that SyntheticProofTask uses ffi.SealCalls in the same way as PoRepTask. The assistant is not reading the file wholesale — it is performing a precise, pattern-based search to extract exactly the information needed to plan the integration.

Input Knowledge Required

To understand this message, one needs several layers of context:

Curio's task architecture: Curio uses a harmony task framework where each task type implements harmonytask.TaskTypeDetails (which declares resource requirements), CanAccept() (which gates task acceptance based on capacity), and Do() (which performs the actual work). Tasks are scheduled by a central engine that polls for available work.

The FFI layer: ffi.SealCalls is a Go struct wrapping C FFI calls to the Filecoin proof libraries (specifically supraseal and lotus). It provides methods like SealCommit2, SealSnark, and SyntheticPoRep that invoke native code for sector sealing and proof generation. This is the interface that must be bypassed when offloading to cuzk.

The cuzk project: The assistant had spent the preceding segments (28–32) designing and implementing the cuzk daemon itself — a C++/CUDA GPU proving service with a split API, memory backpressure, and gRPC interface. The daemon is now operational, and the task at hand is integrating it into Curio.

Go syntax and conventions: The grep pattern ffi\. searches for any use of the ffi package identifier — field declarations (*ffi.SealCalls), function parameters, return types, and error formatting. Understanding that ffi.SectorRef is a type and that sc *ffi.SealCalls is a struct field is necessary to interpret the output.

Output Knowledge Created

The grep output reveals three distinct categories of ffi usage in task_synth_proofs.go:

  1. Struct field: sc *ffi.SealCalls — The SyntheticProofTask struct holds a pointer to the SealCalls instance, exactly as PoRepTask does.
  2. Constructor parameter: NewSyntheticProofTask(sp *SealPoller, db *harmonydb.DB, sc *ffi.SealCalls, maxSynths int) — The constructor accepts sc as a parameter, meaning the SealCalls instance is injected from outside (likely created once and shared across task types).
  3. Method return type and usage: taskToSector returns ffi.SectorRef and uses []ffi.SectorRef for a slice. Error messages reference ffi.SectorRef{} as a zero-value return. This output confirms the assistant's hypothesis: SyntheticProofTask follows the same pattern as PoRepTask. Both hold an *ffi.SealCalls, both receive it via constructor injection, and both use ffi.SectorRef for sector identification. This consistency is crucial — it means the integration pattern can be uniform across task types. But the output also reveals something subtler: the taskToSector method is the only place where ffi types appear beyond the field and constructor. This method converts a harmonytask.TaskID into an ffi.SectorRef by querying the database. This is a key insight for the integration — the sector reference is needed for vanilla proof generation (which stays local), not for the SNARK computation (which goes to cuzk). The assistant can now plan to keep taskToSector unchanged while adding a separate path for SNARK submission.

Assumptions and Their Validity

The assistant makes several assumptions in this message:

Assumption 1: The grep pattern ffi\. will capture all relevant FFI usage. This is a reasonable assumption given Go's package-qualified identifier syntax. However, it could miss indirect usage — for example, if ffi were aliased via import or if methods on ffi types were called without the package prefix in certain contexts (unlikely in Go, but possible with dot-imports). The assistant does not verify this by reading the full file.

Assumption 2: The SyntheticProofTask is a primary target for cuzk integration. This is correct — synthetic proofs are a key part of the PoRep pipeline, and offloading them to cuzk is a primary goal. However, the assistant later discovers that SyntheticProofTask is actually one of the simpler cases; the more complex integration is with task_prove.go (SnapDeals) and proofshare tasks.

Assumption 3: The pattern of constructor injection (sc *ffi.SealCalls) means the cuzk client can be added as another parameter. This turns out to be correct, but it glosses over the complexity of lifecycle management. The cuzk client needs connection management, reconnection logic, and queue monitoring — concerns that don't exist for the local ffi.SealCalls. The assistant addresses these in subsequent messages by creating a dedicated cuzk.Client wrapper.

Assumption 4: The grep output is complete. The assistant does not verify that it has seen every line of the file. In practice, the grep output shows only lines containing ffi. — it does not show the full context of each usage. For example, the taskToSector method might have additional logic that references ffi indirectly. The assistant compensates for this by reading more of the file in subsequent messages.

The Thinking Process Visible in the Message

The assistant's thinking is not explicitly stated in message 3340 itself — it is a bare bash command with output. But the thinking process is visible in the sequence of messages leading up to it:

  1. [msg 3332]: The assistant explicitly states its reasoning: "I'm currently focused on defining the parameters for integrating cuzk with curio... I'm exploring the implications of this design choice." It then runs exploratory commands to find relevant files and understand the CanAccept mechanism.
  2. [msg 3333]: The assistant broadens its search to find all task files related to proof computation, listing files in tasks/window, tasks/winning, tasks/snap, tasks/pdp, and tasks/proofshare.
  3. <msg id=3334–3335>: The assistant narrows to the seal tasks directory, listing files and confirming the presence of task_porep.go and task_synth_proofs.go.
  4. [msg 3336]: The assistant reads the first 20 lines of both files to understand their structure — imports, package declaration, and type definitions.
  5. <msg id=3337–3338>: The assistant probes for TypeDetails() and Name fields, confirming that both tasks are registered in the harmony framework with names "PoRep" and "SyntheticProofs".
  6. [msg 3339]: The assistant searches for ffi usage in task_porep.go, discovering the *ffi.SealCalls field and constructor parameter.
  7. [msg 3340] (the subject): The assistant applies the same search to task_synth_proofs.go, confirming the pattern holds. This sequence reveals a methodical, hypothesis-driven approach. The assistant is not randomly browsing files — it is systematically testing a mental model of the codebase. Each command answers a specific question: "Does this task type use ffi.SealCalls?" "Does it have a TypeDetails() method?" "What is its registered name?" The grep in message 3340 is the culminating verification step for the SyntheticProofTask hypothesis.

The Broader Significance

This message, for all its apparent simplicity, is a microcosm of the entire integration effort. It demonstrates that successful architectural change in a complex system depends on precise, targeted code exploration. The assistant does not need to read every line of task_synth_proofs.go — it needs to find the specific touchpoints where the cuzk client will be inserted. The grep command is a surgical instrument, not a blunt tool.

Moreover, the message illustrates a key principle of the assistant's methodology: parallel exploration followed by targeted verification. The assistant first discovers the landscape broadly (finding all task files, understanding the harmony framework), then drills into specific files with increasing precision. Message 3340 is the drill hitting its mark.

In the messages that follow (<msg id=3341+>), the assistant builds on this knowledge to implement the integration: adding cuzkClient fields to each task struct, modifying constructors, updating Do() methods to call PoRepSnarkCuzk instead of local SNARK functions, and adapting CanAccept() to query the daemon's queue. Every one of those changes traces back to the understanding gained from grep commands like this one.

Conclusion

The single grep command in message 3340 is a testament to the power of focused code exploration. In six lines of output, the assistant confirmed that SyntheticProofTask follows the same ffi.SealCalls injection pattern as PoRepTask, identified the taskToSector method as a local-only concern, and established the template for integrating cuzk across all task types. It is a small but essential step in a larger journey — from understanding the existing architecture to transforming it with a remote proving capability that will fundamentally change how Filecoin storage mining utilizes GPU resources.