Six Bugs That Taught Me How to Build an AI Agent That Doesn't Fall Over

Description and use

The author explains how to fix blocking OAuth, duplicate tool calls, and shared API key quota starvation by creating the kevlar-agent library, which adds timeouts, dedupe, and per‑feature budgeting.

Problem

Unattended AI assistants can silently fail due to blocking OAuth flows, duplicate tool calls, and shared API key quota starvation.

Outcome

The agent now runs unattended for months without silent failures, thanks to timeout handling, dedupe, and per‑feature quota management.

Workflow

• Identify failure modes during real‑world operation
• Implement cross‑platform timeout for OAuth calls
• Add time‑windowed dedupe for tool calls
• Track per‑feature API usage and enforce budget ceilings
• Package solutions into kevlar-agent library
• Integrate library into existing agent stack
• Run 24 tests to validate behavior

Evidence

The OAuth helper that hung for hours… just… waited. For hours. No error, no timeout, no log line saying anything was wrong

Source

Two duplicate tool calls… two near‑simultaneous calls to a "launch session" tool spun up two concurrent audio sessions

Source

Two unrelated features shared a single provider API key… silently ate into the quota the other feature needed

Source