Tracing a Silent Blockade: How a CIDgravity Timeout Stalled an Entire Deal Pipeline

The Message

In a single, deceptively simple message, an AI coding assistant working on a distributed Filecoin storage system made a crucial diagnostic leap. The message reads:

I see — the deal check loop first checks runCidGravityDealCheckLoop which calls GetDealStates. This is what's timing out. Let me see the full deal tracker loop:

>

[read] /home/theuser/gw/rbdeal/deal_tracker.go `` 00041| cfg := configuration.GetConfig() 00042| for { 00043| checkStart := time.Now() 00044| select { 00045| case <-r.close: 00046| return 00047| default: 00048| } 00049| 00050| err := r.runDealCheckLoop(ctx) 00051| if err != nil { 00052| log.Errorw("deal check loop failed", "error", err) 00053| } 00054| 00055| checkDuration := time.Since(checkStart) 00056| 00057| log.Infow("deal check loop finished", "duration", checkDuration) 00058| 00059| if checkDurati... ``

At first glance, this looks like a routine debugging step — the assistant is reading source code to understand a timeout. But this message represents the moment when scattered symptoms coalesced into a specific, testable hypothesis about why a production system had stopped creating Filecoin deals entirely. It is the fulcrum on which the entire debugging session pivots.

Context: A Deal Pipeline Gone Silent

To understand why this message matters, we need to step back. The system under development is a horizontally scalable S3-compatible storage gateway for the Filecoin network, built around a distributed storage engine called Kuri. One of its core responsibilities is managing the lifecycle of Filecoin deals — the on-chain agreements where storage providers agree to store data in exchange for payment. The system has a "deal tracker" component that periodically checks which data groups need deals, queries external APIs to find suitable storage providers, and initiates new deals.

Prior to this message, the assistant had been working on a different problem entirely: removing legacy Lassie/Graphsync retrieval code and enabling HTTP-only repair workers. That work had been committed and was ready for deployment. The user then redirected attention: "First — look at logs and see why rbdeal deals are not flowing, then deploy."

What the assistant found in the logs was alarming. The deal check loop was failing repeatedly with the same error:

ERROR ribs:rbdeal rbdeal/deal_tracker.go:52 deal check loop failed
{"error": "Post \"https://service.cidgravity.com/private/v1/get-on-chain-deals\":
context deadline exceeded (Client.Timeout exceeded while awaiting headers)"}

The CIDgravity API — the external service that provides information about on-chain deal states — was timing out. Every call to get-on-chain-deals was failing. The assistant methodically worked through the diagnostic checklist: Can we reach the host? Yes, TCP connects. Is the API token valid? The initial test with Authorization: Bearer returned 401, but switching to X-API-KEY (the correct header the code actually uses) returned a successful 200 with 5.3MB of data in 2.6 seconds. So the API itself was working fine from the node. Yet the Kuri service was experiencing timeouts that took nearly three minutes to fail.

This is where the subject message lands. The assistant has just realized something fundamental about the architecture of the deal check loop, and it's about to trace through the source code to confirm it.

The Reasoning: Why a Timeout in One Function Blocks Everything

The key insight in the message is the phrase "the deal check loop first checks runCidGravityDealCheckLoop which calls GetDealStates." The assistant has connected two pieces of information:

1. The symptom: runCidGravityDealCheckLoop is timing out, and the error propagates up to runDealCheckLoop, which logs "deal check loop failed."
2. The structural implication: If runCidGravityDealCheckLoop fails, does the rest of the deal pipeline still execute? The assistant reads the source to answer this question. The code at line 424-435 of deal_tracker.go reveals the answer:

func (r *ribs) runDealCheckLoop(ctx context.Context) error {
    cfg := configuration.GetConfig()
    if cfg.CidGravity.ApiToken != "" {
        log.Info("Starting deal check loop cidg check")
        if err := r.runCidGravityDealCheckLoop(ctx); err != nil {
            return err  // <-- This is the problem
        }
    }
    log.Debug("Starting deal check loop SP")
    if err := r.runSPDealCheckLoop(ctx); err != nil {
        return err
    }
    // ... more steps including runDealCheckCleanupLoop which makes new deals
}

The control flow is strictly sequential and uses early return on error. If runCidGravityDealCheckLoop returns an error — any error — the entire function returns immediately. runSPDealCheckLoop never runs. runDealCheckCleanupLoop, which is the function that actually identifies groups ready for deals and initiates new deal proposals, never runs. The entire deal pipeline is gated behind a single API call.

This is the "silent blockade." The system has groups in GroupStateLocalReadyForDeals (state 3), meaning they have been sealed locally and are waiting for Filecoin deals to be made. The wallet has 374 TiB of datacap and sufficient FIL balance. All the prerequisites are met. But because the CIDgravity API call — which is only needed to reconcile existing deal states — keeps timing out, the system never reaches the code that would create new deals. The blockade is invisible from a resource perspective: the node is healthy, the groups are ready, the wallet is funded. The only clue is the recurring timeout error in the logs.

Assumptions and Their Consequences

The assistant's diagnostic approach reveals several implicit assumptions. First, the assistant assumes that the CIDgravity API call is a prerequisite step that must complete before any deal-making logic can proceed — and the source code confirms this. Second, the assistant assumes that the timeout is not a transient network issue but a persistent structural problem, given that it has been failing consistently for hours. Third, the assistant assumes that the correct path forward involves either fixing the timeout (by increasing the client timeout or investigating why the API response takes so long) or restructuring the control flow so that a CIDgravity failure doesn't block the entire pipeline.

There is a subtle incorrect assumption lurking here: the assistant initially assumed that the CIDgravity API was unreachable or misconfigured, spending time testing connectivity and authentication. In reality, the API responded successfully in 2.6 seconds when called directly with curl. The timeout was happening inside the Go HTTP client, which uses a 30-second timeout, while the full response apparently takes 110-160 seconds. The API works — it just takes longer than the client is willing to wait. This distinction matters because it shifts the fix from "fix the API connection" to "increase the timeout or investigate why the response is slow."

Input Knowledge Required

To fully understand this message, one needs familiarity with several domains:

• The Filecoin deal lifecycle: Understanding that groups of data go through states (writable → ready for deals → sealed with deals) and that the deal tracker is responsible for advancing groups through this pipeline.
• The CIDgravity API: An external service that provides information about on-chain deal states and available storage providers. It is a commercial service that the system depends on for deal-making.
• Go concurrency patterns: The select statement with a <-r.close channel case is a standard Go pattern for graceful shutdown. The for loop with time.Now() duration tracking is a common pattern for periodic task execution.
• The system architecture: Kuri nodes run the deal tracker as part of their background processing. The deal check loop runs periodically (the code shows it sleeps if checkDuration is less than some interval).
• HTTP client timeout behavior: The "context deadline exceeded" error indicates the Go HTTP client's context or transport-level timeout was hit, not a TCP connection failure.

Output Knowledge Created

This message produces several valuable pieces of knowledge:

1. Root cause hypothesis: The CIDgravity API timeout is blocking the entire deal pipeline because of the sequential, early-return control flow in runDealCheckLoop.
2. Code confirmation: Reading the source confirms that runCidGravityDealCheckLoop runs first and its error causes an immediate return, preventing runSPDealCheckLoop and runDealCheckCleanupLoop from executing.
3. Actionable next step: The assistant now knows exactly where to look — the runCidGravityDealCheckLoop function and its HTTP client configuration — to understand why the timeout occurs and how to fix it.
4. A clear diagnostic chain: Connectivity works → API responds with correct auth → but the Go client times out → which blocks everything downstream. This chain is the foundation for the subsequent fixes.

The Thinking Process Visible in the Message

The message reveals the assistant's reasoning process in real time. The opening "I see" signals a moment of synthesis — the assistant has just connected the timeout error to the control flow structure. The phrase "the deal check loop first checks runCidGravityDealCheckLoop which calls GetDealStates" shows the assistant tracing the call stack from the error back to the source.

The decision to read the full deal tracker loop source code is itself a diagnostic choice. The assistant could have continued testing the API directly, or checked network configurations, or looked at other components. Instead, the assistant chose to verify the control flow hypothesis by reading the code. This reflects a debugging methodology: when you have a symptom (timeout) and a suspect (CIDgravity API call), trace the control flow to understand the impact before attempting a fix.

The message also reveals what the assistant doesn't say. There is no speculation about why the API is slow — the assistant doesn't jump to conclusions about server load, network routing, or API changes. The focus is on understanding the structural impact first. This is a disciplined debugging approach: understand the mechanism before diagnosing the cause.

Why This Message Matters

In the broader narrative of the coding session, this message is the diagnostic turning point. Before it, the assistant was exploring — checking connectivity, testing authentication, examining wallet balances. After it, the assistant has a clear theory of the failure mode and a roadmap for the fix. The subsequent messages show the assistant checking the CIDgravity client code, discovering the timeout configuration, and ultimately working through a series of fixes including endpoint migration and timeout adjustments.

The message also exemplifies a pattern common in complex distributed systems debugging: the most impactful failures are often not the ones that crash the system, but the ones that silently prevent it from making progress. The CIDgravity timeout didn't cause a panic or a crash — it just caused the deal check loop to return early, every time, forever. Without understanding the control flow dependency, the symptom looked like a network issue. With the control flow understanding, it became clear that the timeout was a gatekeeper failure — a single point of failure that could halt the entire deal pipeline.

This message, then, is a small but perfect example of what makes systems debugging both challenging and rewarding: the moment when scattered data points — a log error, a successful curl test, a source code snippet — suddenly arrange themselves into a coherent story about why the system is stuck.