From Reconnaissance to Implementation: Building a Live Monitoring Dashboard for a GPU Proving Engine

Introduction

In the lifecycle of any complex software project, there comes a pivotal moment when the focus shifts from building the core engine to operationalizing it—wrapping it in the management interfaces, dashboards, and monitoring tools that make it usable in production. This chunk of an opencode coding session captures precisely that transition. The CuZK proving engine—a persistent GPU-resident SNARK proving system for Filecoin—had been through deep, low-level work: implementing Pre-Compiled Constraint Evaluator (PCE) extraction for multiple proof types, debugging a WindowPoSt crash caused by a trait implementation mismatch, and adding partitioned pipelines for SnapDeals. Now, the focus shifted to the operational layer: integrating live monitoring into the vast-manager HTML UI, the web dashboard that operators use to oversee proof pipeline performance across distributed GPU instances.

The messages in this chunk (indices 0 through 9) form a complete sub-session: a targeted codebase exploration that begins with a detailed user request, proceeds through systematic file discovery and analysis, and culminates in a comprehensive architectural recommendation for adding a cuzk status polling feature. This article examines each step of that journey, revealing the reasoning, assumptions, and discoveries that shaped the final design.

The Exploration Mandate

The sub-session began with a meticulously structured user request ([msg 0]). As analyzed in [1], this message was far more than a simple request for information—it was a strategic document revealing the parent session's goals, assumptions, and mental model of the codebase. The six numbered questions formed a logical progression from coarse to fine, mirroring how a developer would naturally explore an unfamiliar codebase. The user asked the assistant to "explore the vast-manager codebase thoroughly" with six specific questions covering overall structure, HTML UI architecture, node tracking data structures, UI rendering logic, existing polling mechanisms, and the SSH poller. The user also specified two directories to investigate: /tmp/czk/cmd/vast-manager/ and /tmp/czk/vast-manager.

This request was not casual. It was a strategic reconnaissance brief, designed to gather the intelligence needed before implementing a new feature. The user's mention of "the SSH poller (mentioned as SSH-based poller for querying cuzk status)" reveals an implicit assumption: that such a poller already exists in some form. The assistant would need to verify this assumption.

The request also specified the desired output format: a detailed summary covering directory structure, web framework, node models, UI rendering, existing endpoints, SSH connection mechanisms, and—most importantly—"where I would need to add a cuzk status polling feature." This last item transforms the exploration from passive observation into active planning, giving the sub-agent a clear deliverable.

Systematic Codebase Discovery

The assistant began with broad file discovery ([msg 1]), issuing three glob commands in parallel to map the codebase terrain. As [3] documents, this opening move was a deliberate strategic choice—the assistant prioritized building a mental map of the codebase before diving into any individual file, minimizing round-trips by batching all three globs into a single message. The results revealed a surprisingly compact project: the vast-manager consisted of just two source files—main.go (the entire Go backend, ~1800 lines) and ui.html (the entire frontend, ~1350 lines)—sitting in /tmp/czk/cmd/vast-manager/. The path /tmp/czk/vast-manager turned out to be a compiled ELF binary, not a directory.

This discovery was significant. It meant that the entire management service was a single Go binary with an embedded HTML file, using only the standard library plus SQLite. There was no external web framework, no template engine, no JavaScript bundler, no WebSocket infrastructure. The simplicity of the architecture would shape the implementation approach for the new monitoring feature.

The assistant then read both source files in their entirety ([msg 2], [msg 3]), absorbing the full structure of the Go service and the HTML dashboard. The Go service used two HTTP listeners: an API port (default :1235) for instance-facing APIs and log push, and a UI port (default :1236) for the web dashboard and management APIs. The HTML file was embedded into the binary at compile time using Go's //go:embed directive.

The UI was a single-page application with inline CSS and vanilla JavaScript—no React, no Vue, no external dependencies. It used a 10-second polling loop to refresh the dashboard, fetching GET /api/dashboard and re-rendering the instance table. There were no WebSockets anywhere in the codebase.

The Search for the SSH Poller

With the basic structure understood, the assistant turned to the specific questions about polling and SSH mechanisms ([msg 4], [msg 5], [msg 6]). A series of targeted grep searches probed the codebase for SSH-related code, polling infrastructure, cuzk status references, and WebSocket patterns. As [5] and [4] explore in depth, these grep commands were not random—each pattern was a hypothesis about the codebase's naming conventions, and the sequence of searches revealed the assistant's systematic approach to negative verification.

The results were revealing. The grep for ssh|SSH|poller|poll|cuzk.*status|cuzkStatus|sshPoll found 20 matches in main.go and 5 in ui.html—but every match was about SSH command storage, not SSH command execution. The codebase stored SSH commands as strings (e.g., ssh -p 12345 root@1.2.3.4) and displayed them in the UI with a "copy SSH" button, but there was no code that actually connected to instances via SSH.

A second grep with more specific patterns—cuzk|status.*poll|ssh.*poll|9820|cuzk-bench—found only superficial references: a CSS class name, a log tab label, comment lines, and a Docker image reference. The patterns status.*poll, ssh.*poll, 9820 (the cuzk daemon's HTTP port), and cuzk-bench (the CLI tool for querying cuzk status) all returned zero results.

A third grep for WebSocket patterns (websocket|WebSocket|ws://|wss://) returned "No files found."

The assistant also checked for SSH library imports ([msg 6]), searching for golang.org/x/crypto/ssh and x/crypto/ssh across the entire repository. The only match was golang.org/x/crypto/sha3 in an unrelated file. The go.mod file confirmed that no SSH client library was listed as a dependency.

The conclusion was definitive: the SSH poller did not exist. The user's assumption was incorrect. The project's design document (vast-cuzk-plan.md) described manual SSH commands that operators could run to check cuzk status, but no automated polling mechanism had been implemented. The "SSH poller" was a gap, not a feature.

Resolving the Binary Ambiguity

One of the more interesting moments in the exploration came when the assistant tried to read /tmp/czk/vast-manager ([msg 7]). The read tool returned empty content—the path was not a text file. The assistant then used the Unix file command ([msg 8]) to identify the mysterious entry. As [2] describes, this single command resolved an ambiguity that had persisted since the initial glob results, transforming an unknown path into a known compiled binary with specific build characteristics.

/tmp/czk/vast-manager: ELF 64-bit LSB executable, x86-64, version 1 (SYSV),
dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2,
BuildID[sha1]=7a1b8c1b72aa91ff41abaee2957473698a5c6485,
for GNU/Linux 4.4.0, with debug_info, not stripped

This was a compiled Go binary—the built vast-manager executable. Its presence at the repository root, alongside the source in cmd/vast-manager/, suggested a straightforward build-and-deploy workflow. The binary was dynamically linked (likely due to the SQLite CGO dependency), included debug info (a development build), and targeted Linux x86-64. This discovery resolved the ambiguity about the project structure and confirmed that the source code was the authoritative reference for the implementation.

The Comprehensive Summary

With the exploration complete, the assistant synthesized everything into a detailed architectural summary ([msg 9]). This summary is the deliverable that the user requested, and it serves as the blueprint for the next phase of implementation.

The summary covered:

Directory structure: The vast-manager lives in cmd/vast-manager/ with just main.go and ui.html. The deploy/ directory contains a systemd unit file. Design documents (vast-cuzk-plan.md, cuzk-project.md, cuzk-phase2-design.md) provide architectural context.

Web framework: Pure Go standard library—no external web framework. Two HTTP listeners (API and UI). The HTML is embedded via //go:embed. The frontend is a vanilla JS SPA with a 10-second polling loop.

Node data structures: Four key structs—Instance (SQLite row), VastInstance (live Vast API data), DashboardInstance (merged view sent to UI), and a PortBinding type. SSH commands are computed from Vast API port mappings and stored as strings.

UI rendering: Click-to-expand detail grid showing 25+ fields, plus a log viewer with source filtering tabs. No WebSocket infrastructure.

Existing polling: A background goroutine (runMonitor) polls the Vast API every 60 seconds. The UI polls /api/dashboard every 10 seconds. No SSH-based polling exists.

SSH poller status: Confirmed nonexistent. The design document describes manual SSH commands, but no automated polling has been implemented.

Integration points: The summary concluded with a detailed, line-numbered recommendation for where and how to add the cuzk status polling feature. This included adding an SSH client dependency (golang.org/x/crypto/ssh), creating new data structures (CuzkStatus), adding a status cache to the Server struct, implementing an SSH poller goroutine, exposing status in the dashboard API, extending the DashboardInstance struct with cuzk-specific fields, and adding UI elements to the instance table, detail grid, and summary cards.

The recommendation also noted a key consideration: the SSH key for connecting to instances is not currently managed by vast-manager. The instances are created with --ssh --direct, meaning Vast.ai sets up SSH access. The manager would need to either use the Vast.ai SSH key (typically at ~/.ssh/id_rsa on the controller) or add an SSH key path configuration flag.

The Architecture of the Solution

The recommended architecture reflects a deep understanding of both the existing codebase and the requirements of the new feature. Several design decisions are worth examining:

SSH ControlMaster for connection reuse: Rather than opening a new SSH connection for each polling cycle, the recommendation implicitly suggests using SSH ControlMaster—a feature that allows multiple SSH sessions to share a single TCP connection. This is critical for efficiency when polling dozens of instances every 30-60 seconds. Without connection reuse, the overhead of SSH key exchange and session establishment would dominate the polling cycle.

In-memory status cache: The sync.Map for caching cuzk status avoids hitting the database or SSH connections on every dashboard refresh. The background poller updates the cache, and the dashboard API reads from it. This decouples the polling frequency (every 30-60 seconds) from the UI refresh frequency (every 10 seconds).

Minimal dependency footprint: The recommendation adds only one new dependency (golang.org/x/crypto/ssh) to the existing codebase. This aligns with the project's philosophy of minimal dependencies—the existing service uses only the Go standard library plus SQLite.

Separation of concerns: The poller runs as a background goroutine, separate from the HTTP handlers. This ensures that slow SSH connections don't block API responses, and that the dashboard remains responsive even if some instances are unreachable.

The Thinking Process Revealed

The assistant's reasoning throughout this exploration reveals a systematic, methodical approach to codebase understanding. Several patterns are worth noting:

Start broad, then narrow: The assistant began with glob-based file discovery, then read the main source files, then used targeted grep searches for specific patterns. This progression from broad to narrow is the same strategy a human developer would use when approaching an unfamiliar codebase.

Verify assumptions: The user assumed an SSH poller existed. The assistant did not take this at face value—it searched for SSH execution code, polling infrastructure, cuzk status references, and WebSocket patterns across multiple searches, each using different patterns. Only after exhaustive verification did the assistant conclude that the poller did not exist.

Resolve ambiguities: When the read tool returned empty content for /tmp/czk/vast-manager, the assistant didn't ignore the discrepancy—it used the file command to resolve the ambiguity. This attention to detail prevented a misunderstanding of the project structure.

Synthesize findings into actionable recommendations: The final summary is not just a list of observations—it is a blueprint for implementation, with specific file paths, line numbers, and code patterns. The assistant transformed raw exploration data into actionable engineering guidance.

From Exploration to Implementation

The exploration summarized in this chunk set the stage for the implementation that followed. The assistant now knew:

Conclusion

This chunk of the opencode session demonstrates the critical role that systematic codebase exploration plays in successful feature implementation. The assistant's methodical approach—starting with broad file discovery, reading source files, performing targeted searches, resolving ambiguities, and synthesizing findings into actionable recommendations—transformed an unfamiliar codebase into a well-understood terrain ready for modification.

The key discoveries—that the SSH poller did not exist, that the codebase was a minimal Go service with embedded HTML, that the UI used a simple polling loop without WebSockets, and that the SSH commands were stored but never executed—shaped the entire architecture of the new monitoring feature. Without this exploration, the implementation would have been built on incorrect assumptions and would likely have required significant rework.

The exploration also revealed the importance of questioning assumptions. The user's belief that an SSH poller existed was reasonable given the project documentation, but the assistant's verification process prevented the implementation from being built on a false foundation. In software engineering, the most valuable knowledge is often not what exists, but what does not exist—and the assistant's thorough negative verification was the most important contribution of this exploration phase.## References

[1] "The Exploration Mandate: How a Single Message Launched a Deep Codebase Reconnaissance" — Analyzes message 0 as a strategic discovery brief, examining its assumptions, reasoning, and role in the broader session.

[2] "The Moment a File Reveals Its True Nature: Identifying a Compiled Binary in a Codebase Exploration" — Examines message 8 and the use of the file command to resolve the ambiguous path.

[3] "The First Step: Initiating Codebase Exploration in a Subagent Session" — Analyzes message 1 and the strategic choice of glob-based file discovery as the opening move.

[4] "The Negative Result: How a Targeted Grep Shaped the Architecture of a Proving Dashboard" — Examines message 5 and the significance of confirming the absence of an SSH poller.

[5] "The Art of Targeted Codebase Exploration: A Deep Dive into a Single Grep Command" — Analyzes message 4 and the systematic grep-based search for SSH and polling infrastructure.

[6] "Reading the Blueprint: How an AI Assistant Strategically Explores an Unknown Codebase" — Analyzes message 2 and the reading of main.go and ui.html.

[7] "The Moment of Discovery: Verifying a Binary at the Repository Root" — Analyzes message 7 and the attempt to read the vast-manager path.

[8] "Systematic Codebase Exploration: A Deep Dive into a Single Read Operation" — Analyzes message 3 and the continuation of file reading.

[9] "Mapping the Territory: A Deep Dive into Codebase Exploration for Feature Planning" — Analyzes message 9 and the comprehensive architectural summary.

[10] "The Missing SSH Poller: A Pivotal Discovery in the vast-manager Codebase Exploration" — Analyzes message 6 and the confirmation that no SSH polling library exists.