Building In-Browser Coding Agents: Verification is the Main Bottleneck

Death12th · reddit · 2026-08-05

The author shares experience in building an agentic tool loop for an in-browser coding environment. The agent handles planning, editing, and verification.

The biggest challenge is the verification step. Because the model's self-report is uniformly optimistic, the system must gate completion on actual behavior—running the code and checking outcomes—rather than trusting the model's claim of being "done".

For cost management, the system uses a cheap-to-expensive fallback chain across multiple providers. Most requests are handled by cheaper models (like Bedrock), reserving expensive models only when necessary. However, the routing logic is still mostly based on heuristics.

Original post →

More from coding & agent

coding & agent channel →