release

What’s New in v0.8.0

Gasoline v0.8.0 focuses on reliability and consistency across the daemon, extension, and test harness.

Highlights

Unified sync-era behavior by removing legacy split-result paths and aligning command/result flow through /sync.
Hardened screen-recording UX with clearer approval status and improved popup/recording state handling.
Improved command and context-menu state consistency for recording and annotation-related controls.
Installer hardening updates for safer staging, replacement, and verification flows.
Broader regression coverage across Go and extension test suites, including updated contracts and goldens.

Quality Gates

make test
make test-js

Both passed for the v0.8.0 release cut.

Upgrade

npx gasoline-agentic-browser@0.8.0

Full Changelog

View v0.8.0 on GitHub

What’s New in v0.7.0

v0.7.0 is a ground-up rewrite delivering a complete browser observability platform. This is the first stable release — all prior versions are deprecated.

Highlights

Zero-dependency Go daemon with MCP JSON-RPC 2.0 protocol — no runtime dependencies, single binary
Chrome MV3 extension capturing console logs, network requests, DOM state, screenshots, and Web Vitals in real-time
5 MCP tools — observe, generate, configure, interact, analyze — giving AI agents full browser visibility
File upload pipeline with 4-stage escalation and OS automation for native file dialogs
Draw mode for visual region selection and annotation directly in the browser
SARIF export for integrating accessibility and security findings into CI/CD pipelines
Session recording with WebM video capture
Pilot mode for autonomous browser interaction via AI agents
Link health analysis with CORS detection
npm + PyPI distribution with auto-update daemon lifecycle

Features

Complete MCP server with tool-based architecture (observe, generate, configure, interact, analyze)
Real-time browser telemetry: console, network, WebSocket, DOM, performance, errors
HAR and SARIF export for network traces and accessibility audits
Test generation from browser interactions (Playwright, Vitest)
Noise filtering with persistent rules
CSP policy generation from observed network traffic
Network waterfall analysis with body capture

Install

npx gasoline-mcp@0.7.0

Or with pip:

pip install gasoline-mcp==0.7.0

Full Changelog

View on GitHub

What’s New in v6.0.0

Gasoline v6.0.0 introduces the Link Health Analyzer, plus browser automation, recording, and performance analysis for AI agents. Check all links on your page, record full sessions with video, capture performance metrics, and let AI agents test, debug, and fix your app automatically. Complete visibility. You stay in control.

Features

Link Health Analyzer — Automatically check all links on your page for issues (broken, redirects, auth-required). 20 concurrent checks, categorized results, and async tracking with correlation IDs.
Full Recording System — Record browser tabs with video and audio. Videos stream to local disk. No cloud, no transcoding—raw WebM format.
Permission Prompts — When recording starts, you get a clear prompt to approve it. No silent recordings. You’re always in control.

Security

CWE-942 Fixed — Replaced wildcard postMessage origins with window.location.origin across content scripts, test helpers, and background workers. Prevents message hijacking on cross-origin pages.
Secure Cookie Attributes — Cookie deletion and restoration now include Secure and SameSite attributes, preventing session fixation and CSRF vulnerabilities.
Path Traversal Protection — Hardened file operations in extension persistence layer to prevent directory traversal attacks.
Input Validation — Comprehensive validation of extension log queue capacity (2000-entry cap) and screenshot rate limiter bounds to prevent unbounded memory growth.

Performance

Smart HTTP Timeouts — 5s default timeout for localhost operations, extended to 30s+ only when accessibility features are requested. Reduces false positives while respecting slow connections.
Atomic File Writes — Log rotation uses temp + rename pattern, preventing partial writes and data loss on disk full.
Efficient Deduplication — SeenMessages pruning optimized for large event volumes.

Testing

99.4% Pass Rate — 154 out of 155 smoke tests pass (one known edge case with watermark on rapid navigation).
Comprehensive UAT Suite — 140 tests covering recording, permissions, security, performance, and WebSocket capture.
Full TypeScript Strict Mode — No implicit any, zero Codacy security issues.

Breaking Changes

Extension v5.x → v6.0.0 — Auto-update via Chrome. Manual re-add may be required if permissions are denied.
MCP Server — Same 4-tool interface; no API changes.

Upgrade

Browser Extension

Direct CRX download for this historical beta build is no longer distributed from this docs site. Use the current installer flow instead:

Full installation guide →

MCP Server

npm install -g gasoline-mcp@6.0.0
gasoline-mcp --help

Or via pip:

pip install gasoline-mcp==6.0.0

Known Limitations

Recording audio on muted tabs — Tab audio capture requires tab to have sound playing. Silent tabs record video only.
Watermark on rapid navigation — Watermark may not re-appear if user navigates during recording. Next navigation resets correctly.
Chrome 120+ only — Manifest v3 (MV3) requires Chrome 120 or later. No Safari/Firefox support in v6.

What’s Next

File Upload API — Automated file form handling for bulk uploads to no-API platforms.
Replay System — Event playback with timeline scrubbing.
Deployment Integration — Capture git-linked deploy events for post-incident correlation.

Full Changelog

v5.8.0…v6.0.0

Gasoline v5.7.4 Released

Feb 7, 2026

Brenn Hill

What’s New in v5.7.4

Gasoline v5.7.4 improves stability and MCP protocol reliability based on production feedback.

Improvements

Better handling of slow client connections
Improved timeout recovery and reconnection logic
Enhanced message serialization performance
More robust error reporting to clients

Fixes

Fixed observer timeout on pages with extremely high event volume
Resolved occasional message ordering issues
Improved cleanup of abandoned connections
Better resilience to malformed MCP requests

Performance

Reduced latency for high-frequency events
Optimized buffer management for large responses

Upgrade

npm install -g gasoline-mcp@5.7.4

Full Changelog

v5.7.4 Release

Gasoline v5.8.0 Released

Feb 6, 2026

Brenn Hill

What’s New in v5.8.0

Gasoline v5.8.0 solves a long-standing WebSocket capture blind spot: pages that create WebSocket connections before the inject script loads now have those connections captured automatically. This release also adds visual feedback for AI actions and ships a comprehensive 106-test UAT suite.

Features

Early-patch WebSocket capture — A new world: "MAIN" content script patches window.WebSocket before any page JavaScript runs. This means sites like Binance that create WebSocket connections immediately on page load now have those connections captured and visible via observe(websocket_status). Buffered connections are seamlessly adopted when the full inject script initializes.
Visual action toasts — When AI tools use interact() to navigate, execute JavaScript, or highlight elements, a brief toast overlay appears on the page showing what the AI is doing. This makes AI actions visible to developers watching the browser.

Fixes

Fixed camelCase to snake_case field mapping for network waterfall entries (duration, transfer_size, etc.)
Command results now route through the /sync endpoint with proper client ID filtering
After navigation, tracking state is broadcast so favicon updates correctly
Empty arrays return [] instead of null in JSON responses
Bridge timeouts now return a proper extension_timeout error code

Testing

106-test parallel UAT suite replacing the previous 8-test script, covering observe, generate, configure, interact, and data pipeline categories
16-test human smoke test with error clusters, DOM query, full form lifecycle, highlight, and real WebSocket traffic tests
All tests default to fail (not pass) with strict field validation throughout

Performance

Binary sizes decreased ~4% from v5.7.5. All SLOs continue to pass:

MCP fast-start: ~130ms
Tool response: < 1ms
Max binary: 7.7 MB (target: < 15 MB)

Upgrade

npx gasoline-mcp@5.8.0

Full Changelog

v5.7.5…v5.8.0

Gasoline v5.6.0 Released

Feb 6, 2026

Brenn Hill

What’s New in v5.6.0

Gasoline v5.6.0 focuses on server-side reliability with persistence guarantees and comprehensive architecture invariant tests.

Features

Persistent Message Queue — Guarantees no messages lost during server restarts
Transaction-Safe State — Atomic operations for observer state updates
Architecture Validation — New test suite validating core invariants

Improvements

Improved graceful shutdown of long-running observations
Better handling of concurrent client connections
Enhanced observability into server health and performance
Stricter validation of MCP protocol compliance

Testing

50+ new architecture invariant tests
Stress testing with high message volume
Connection resilience testing

Upgrade

npm install -g gasoline-mcp@5.6.0

Full Changelog

v5.6.0 Release

Gasoline v5.7.5 Released

Feb 6, 2026

Brenn Hill

What’s New in v5.7.5

This release makes Gasoline MCP feel instant. The new fast-start mode responds to MCP clients in ~130ms while the daemon boots in the background.

Fast-Start MCP Mode

Previously, MCP clients had to wait for the full daemon to boot before getting any response. Now, initialize and tools/list respond immediately from the bridge process:

Before: Client → wait 2-4s for daemon → get response
After:  Client → get response in ~130ms → daemon boots in background

This means your AI coding agent gets tool definitions instantly and can start planning while the server finishes starting up. If you call a tool before the daemon is ready, you get a helpful retry message instead of a hang.

Port Conflict Diagnostics

The --doctor command now checks if port 7890 is available:

npx gasoline-mcp --doctor

# Now shows:
# ✅ Port 7890
#    Default port is available
#
# Or if blocked:
# ⚠️  Port 7890
#    Port 7890 is in use (PID: 12345)
#    Suggestion: Use --port 7891 or kill the process using the port

Better Error Messages

When the daemon can’t start because the port is blocked, you now get actionable suggestions:

Server failed to start: port 7890 already in use. Port may be in use. Try: npx gasoline-mcp --port 7891

Faster Failure Detection

Daemon startup timeout reduced from 10s to 4s. If something is wrong, you’ll know in 4 seconds instead of 10.

Upgrade

npx gasoline-mcp@5.7.5

Full Changelog

See the complete list of changes on GitHub.

Gasoline v5.7.0 Released

Feb 5, 2026

Brenn Hill

What’s New in v5.7.0

This release focuses on reliability and developer experience improvements, with a new graceful shutdown system and improved extension connectivity.

Graceful Server Shutdown

Stop running servers cleanly with the new --stop flag:

gasoline-mcp --stop                # Stop server on default port (7890)
gasoline-mcp --stop --port 8080    # Stop server on specific port

The shutdown uses a hybrid approach for maximum reliability:

PID file (fast) - Reads process ID from ~/.gasoline-{port}.pid
HTTP endpoint (graceful) - Sends shutdown request to /shutdown
lsof fallback - Finds process by port if other methods fail

Sync Protocol

The extension now uses a server-sent events based /sync endpoint instead of polling. This means:

Lower CPU usage when idle
Faster response to server queries
More reliable connection state tracking

Server Always Runs as Daemon

The --persist flag has been removed. The server now always runs as a background daemon that persists until explicitly stopped with --stop.

Internal Improvements

New regression test framework in tests/regression/
Comprehensive UAT test suite with shutdown tests
Major documentation cleanup (40+ obsolete files removed)
Better error handling for multi-client scenarios

Upgrade

npx gasoline-mcp@5.7.0

Or if you’ve installed globally:

npm install -g gasoline-mcp@5.7.0

Full Changelog

See the complete list of changes on GitHub.

Gasoline v5.4.1 Released

Jan 18, 2026

Brenn Hill

What’s New in v5.4.1

Quick patch release fixing element selection and interaction issues in v5.4.0.

Fixes

Fixed semantic selector matching on shadow DOM elements
Resolved toast visibility on pages with z-index layering
Improved form field detection for hidden labels
Better handling of contenteditable elements

Upgrade

npm install -g gasoline-mcp@5.4.1

Full Changelog

v5.4.1 Release

Gasoline v5.4.3 Released

Jan 18, 2026

Brenn Hill

What’s New in v5.4.3

Gasoline v5.4.3 includes additional bug fixes and stability improvements following v5.4.1.

Fixes

Fixed click handling on elements inside iframes
Resolved memory leak in toast notification cleanup
Improved robustness of element scrolling
Better error recovery when pages reload during interaction

Performance

Reduced CPU usage during idle observation
Optimized selector matching algorithm

Upgrade

npm install -g gasoline-mcp@5.4.3

Full Changelog

v5.4.3 Release

Gasoline v5.4.0 Released

Jan 17, 2026

Brenn Hill

What’s New in v5.4.0

Gasoline v5.4.0 redesigns the interaction model for better AI agent integration and reliability.

Features

Improved interact() Tool — More reliable element selection and action execution
Visual Feedback — Toast notifications for AI-triggered interactions
Better Form Handling — Enhanced form filling with validation awareness
Robust Navigation — Improved page load detection and state tracking

Improvements

More deterministic element targeting with semantic selectors
Better handling of dynamic content and SPA navigation
Improved timeout handling for slow operations
Enhanced compatibility with modern web frameworks

Fixes

Fixed element visibility detection on overlaid modals
Resolved form submission race conditions
Improved navigation state after dialog close

Upgrade

npm install -g gasoline-mcp@5.4.0

Full Changelog

v5.4.0 Release

Gasoline v5.3.0 Released

Jan 13, 2026

Brenn Hill

What’s New in v5.3.0

Gasoline v5.3.0 adds comprehensive WebSocket inspection and significant performance improvements.

Features

WebSocket Capture — Full message tracking for WebSocket connections
Real-time Message Streaming — Monitor WebSocket traffic as it happens
Binary Message Support — Handle binary WebSocket frames alongside text
Connection State Tracking — Visualize connection open/close lifecycle

Performance

40% reduction in memory overhead
Optimized log buffer management
Faster message serialization

Fixes

Fixed observer timeout on high message volume
Improved handling of concurrent connections
Better cleanup of abandoned resources

Upgrade

npm install -g gasoline-mcp@5.3.0

Full Changelog

v5.3.0 Release

Gasoline v5.2.5 Released

Jan 12, 2026

Brenn Hill

What’s New in v5.2.5

Gasoline v5.2.5 focuses on stability and fixes edge cases discovered in production use.

Improvements

Better handling of rapid tab switching
Improved memory cleanup on long sessions
Fixed race conditions in message queue
Enhanced resilience to malformed responses

Fixes

Resolved observer disconnection on network errors
Fixed log queue overflow handling
Improved error message formatting for edge cases

Upgrade

npm install -g gasoline-mcp@5.2.5

Full Changelog

v5.2.5 Release

Gasoline v5.2.1 Released

Jan 10, 2026

Brenn Hill

What’s New in v5.2.1

Quick patch release fixing issues with error clustering in v5.2.0.

Fixes

Fixed error clustering not deduplicating similar stack frames
Resolved network filter persistence across tab navigation
Improved WebSocket connection tracking stability

Upgrade

npm install -g gasoline-mcp@5.2.1

Full Changelog

v5.2.1 Release

Gasoline v5.2.0 Released

Jan 10, 2026

Brenn Hill

What’s New in v5.2.0

Gasoline v5.2.0 improves error handling, network inspection, and adds better filtering options for high-volume environments.

Features

Enhanced Error Clustering — Group related errors for clearer debugging
Network Filtering — Filter requests by status, content-type, and size
Better Error Context — Stack traces and request/response details inline
Performance Improvements — Reduced memory usage on long-running sessions

Improvements

Error deduplication across similar stack traces
Network waterfall visualization improvements
Better handling of WebSocket connections
Improved timeout handling for slow networks

Upgrade

npm install -g gasoline-mcp@5.2.0

Full Changelog

v5.2.0 Release

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-agentic-browser-devtools-mcp 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-agentic-browser-devtools-mcp 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-agentic-browser-devtools-mcp 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-agentic-browser-devtools-mcp for source.