Blog | Gasoline MCP

Gasoline v5.0.0 Released

Jan 4, 2026

Brenn Hill

What’s New in v5.0.0

Gasoline v5.0.0 marks the initial public release of the Gasoline MCP protocol and extension. This release includes core browser observability features for AI coding assistants.

Features

Browser Telemetry Capture — Real-time streaming of console logs, network requests, and exceptions
MCP Protocol Integration — Compatible with Claude Code, Cursor, Copilot, and other MCP clients
4-Tool Interface — observe, generate, configure, interact tools for full-stack automation
Zero Dependencies — Lightweight Go binary with no external service requirements

Capabilities

Real-time log and error capture
Network request/response inspection
Page interaction and automation
CSS-based element highlighting
Form filling and submission automation

Get Started

npm install -g gasoline-mcp
gasoline-mcp --help

Install the browser extension from the Chrome Web Store or load it manually via Developer Mode.

Full Changelog

v5.0.0 Release

Gasoline v4.0.0 Released

Dec 22, 2025

Brenn Hill

What’s New in v4.0.0

Gasoline v4.0.0 is the refinement phase. The core architecture from v3 works well—this version focuses on making it robust and adding missing developer-focused features.

Major Features

User Action Recording — Record clicks, typing, navigation with smart selectors
Web Vitals Capture — LCP, CLS, INP, FCP tracking
API Schema Inference — Auto-detect OpenAPI patterns from network traffic
Error Aggregation — Group and deduplicate similar errors
Session Checkpoints — Save browser state, diff changes, detect regressions

Performance

Optimized ring buffers — 2000-event cap prevents unbounded memory growth
Efficient filtering — Skip irrelevant logs (ads, tracking, etc.)
Smart deduplication — Collapse repeated identical events
Rate limiting — Respect browser and extension quotas

Developer Experience

Better error messages — Clear explanations of what went wrong and why
Command-line flags — --port, --server, --api-key for flexibility
Health check endpoint — /health for verifying setup
Example integration — Claude Code, Cursor, Copilot configs included

Stability

Comprehensive testing — 80+ unit and integration tests
Error recovery — Graceful handling of extension crashes/restarts
Logging improvements — Debug mode for troubleshooting
TypeScript strict mode — Zero implicit any

Known Limitations

Recording still in alpha (no video yet)
No Safari/Firefox support (MV3 requirement)
Replay system not yet implemented
Limited to Chrome 120+

Status: This version proved the concept could handle real-world usage. Ready for broader testing.

Next: Production-grade recording system, broader browser support research, performance benchmarking.

See [GitHub](https://github.com/brennhill/gasoline-mcp-ai-devtools for source.

Gasoline v3.0.0 Released

Dec 19, 2025

Brenn Hill

What’s New in v3.0.0

Gasoline v3.0.0 replaces the HTTP polling disaster with a proper MCP stdio server. This was the breakthrough version.

Major Changes

Stdio-based MCP Server — Proper bidirectional JSON-RPC 2.0 over stdio
Real-time streaming — Events stream immediately, no polling
All 4 tools implemented — observe(), generate(), configure(), interact()
Event types — Console logs, network requests, WebSocket messages, exceptions

Features

Console Logs — Full argument capture, log levels
Network Capture — Request/response bodies, headers, status codes
WebSocket Events — Message payloads and connection lifecycle
Exceptions — Stack traces and error context
User Actions — Click/type/navigate event recording
Persistence — Logs survive server restart (SQLite backend)

Architecture

Extension → Go daemon (localhost HTTP)
Daemon ↔ MCP client (stdio, bidirectional)
Ring buffer for event history
Persistent storage for audit trail

Performance

<100ms latency for event delivery
Concurrent clients — Multiple AI tools can connect simultaneously
Low memory — Circular buffer limits are enforced
Zero external deps — Pure Go stdlib

Known Limitations

Chrome-only — Manifest V3 requirement
Local network only — Binds to 127.0.0.1
No replay — Can’t scrub through history yet
Recording not yet implemented

Milestone: This was the version that proved the concept could work. Everything from here builds on this foundation.

See [GitHub](https://github.com/brennhill/gasoline-mcp-ai-devtools for source.

Gasoline v2.0.0 Released

Dec 14, 2025

Brenn Hill

What’s New in v2.0.0

Gasoline v2.0.0 adds MCP protocol support. The implementation is naive and has significant limitations, but it works as a proof of concept.

Features

MCP Protocol (Naive) — Basic JSON-RPC 2.0 transport over HTTP
Console Logs + Network Errors — Extension captures logs and failed API calls (4xx, 5xx)
Simple Resource API — resources/list and resources/read endpoints
Multi-tool stub — Four tools defined but only one partially implemented

Architecture

Extension → Go server (HTTP)
Go server → MCP client (HTTP polling)
Blocking request/response model

What We Learned

This version taught us that:

HTTP polling is too slow for real-time telemetry
Single-request blocking architecture doesn’t work for streaming data
MCP needs bidirectional communication, not request/response

Limitations

Performance — 500ms+ latency due to polling
Streaming — Can’t stream data in real-time
Single tool — Only observe() partially works
Network overhead — Constant polling even with no data

Known Issues

Random timeouts on concurrent requests
Lost messages during high-frequency events
Extension crashes if server is restarted

Lesson learned: HTTP polling doesn’t work for a telemetry system. Next version will use WebSockets.

See [GitHub](https://github.com/brennhill/gasoline-mcp-ai-devtools for source.

Gasoline v1.0.0 Released

Dec 11, 2025

Brenn Hill

What’s New in v1.0.0

Gasoline v1.0.0 is the first public release. It’s a proof of concept showing a Go server talking to a Chrome extension to capture browser telemetry.

Features

Basic Browser Telemetry — Chrome extension captures console logs and sends them to a local Go server
HTTP API — Simple REST endpoints to retrieve captured logs
Local-only — All data stays on 127.0.0.1, no cloud services
Zero dependencies — Go binary with no external packages

Architecture

Chrome extension (MV3) — Listens to console.log() calls
Go HTTP server (port 7890) — Receives and stores logs in memory
Local persistence — Logs written to disk

Known Limitations

Console logs only (no network, exceptions, or WebSockets)
Single client only
No MCP protocol yet
Memory-based storage (logs lost on restart)

Installation

go build -o gasoline ./cmd/server
./gasoline

# Then load the extension in chrome://extensions/

This is early. Very early. But it works.

Next steps: Add network request capture, implement MCP protocol, persistent storage.

See [GitHub](https://github.com/brennhill/gasoline-mcp-ai-devtools for source.