worldmonitor/todos/164-pending-p3-fetch-sector-dependency-no-circuit-breaker.md

status, priority, issue_id, tags, dependencies

status	priority	issue_id	tags	dependencies
pending	p3	164	code-review quality supply-chain reliability

fetchSectorDependency Has No Circuit Breaker — Retries Indefinitely on Persistent Failure

Problem Statement

src/services/supply-chain/index.ts:fetchSectorDependency() catches all errors and returns emptySectorDependency. While this prevents crashes, it means every call during a persistent outage (e.g., server restart, network partition) makes a live gRPC attempt before falling back. If the supply-chain panel calls this per-chokepoint on every render, a 30-chokepoint list during an outage = 30 sequential timeouts per render cycle.

Findings

• File: src/services/supply-chain/index.ts
• Code:

  export async function fetchSectorDependency(iso2, hs2 = '27') {
    try {
      return await client.getSectorDependency({ iso2, hs2 });
    } catch {
      return { ...emptySectorDependency, iso2, hs2 };
    }
  }
  

• No timeout, no cached failure state, no back-off
• Minor issue today (called rarely), but will matter at scale
• Identified by kieran-typescript-reviewer during PR #2910 review

Proposed Solutions

Option A: Add a short timeout to the gRPC call

const ac = new AbortController();
setTimeout(() => ac.abort(), 3000);
return await client.getSectorDependency({ iso2, hs2 }, { signal: ac.signal });

Fails fast, reduces hung call duration. Effort: Small | Risk: Low

Option B: Deduplicate in-flight requests with a request Map

Cache the promise keyed by ${iso2}:${hs2} — deduplicates concurrent calls for the same country. Effort: Small | Risk: Low

Recommended Action

Combine A + B: timeout + in-flight dedup. Low-effort, prevents worst-case pile-up.

Technical Details

• Affected files: src/services/supply-chain/index.ts

Acceptance Criteria

• fetchSectorDependency times out within ~3s rather than hanging indefinitely
• Concurrent calls for the same (iso2, hs2) share one in-flight promise

Work Log

• 2026-04-10: Identified by kieran-typescript-reviewer during PR #2910 review

Resources

• PR: #2910