izlek

izlek is a terminal-first local frontend observability tool for humans and coding agents. It starts a development project against a named backend environment, captures bounded process logs and proxied HTTP traffic, renders a focused TUI, and exposes the same live session through a read-only MCP server.

izlek is an early standalone bootstrap extracted from a working internal developer-tooling prototype. Its configuration and public interfaces may change before the first stable release.

Why izlek

Frontend debugging in a monorepo rarely happens in one terminal stream. Build output, package watchers, runtime errors, remote backends, and failed requests all belong to the same development session. izlek keeps that context together without replacing Turbo, Nx, pnpm, Yarn, npm, or browser DevTools.

The foreground izlek dev process owns the session. It supervises the configured command, optionally starts a bounded HTTP recorder, retains recent diagnostics in memory, renders the TUI, and exposes a permission-restricted local socket. Other terminal commands and MCP clients query that socket.

Command surface

izlek dev web --env staging
izlek attach
izlek status
izlek logs --errors
izlek network --failed
izlek inspect request-42
izlek mcp

Current capabilities

• Generic shell-free development command per project
• Named backend environments selected when the session starts
• Bounded process logs with source, stream, level, and timestamp metadata
• Streaming HTTP reverse proxy with bounded request/response capture
• Sensitive-header and captured JSON-field redaction before storage
• Bounded network history and request inspection
• Dev and Network TUI views
• Read-only local session socket shared by CLI and MCP consumers
• Read-only stdio MCP tools for status, logs, errors, and HTTP records
• Coordinated child-process shutdown with TERM-to-KILL escalation
• Layered shared and ignored local configuration

Install for development

npm install
npm link
izlek --help

izlek requires Node.js 20.9 or newer.

Configure a project

Run izlek config init for a minimal generic configuration, or create izlek.config.json:

{
  "projects": {
    "web": {
      "command": ["npm", "run", "dev"],
      "defaultEnvironment": "local",
      "backend": {
        "listen": "127.0.0.1:30998",
        "envVar": "NEXT_PUBLIC_API_URL"
      }
    }
  },
  "environments": {
    "local": {
      "target": "http://127.0.0.1:8080",
      "healthCheck": "/health"
    },
    "staging": {
      "target": "https://api.staging.example.com"
    }
  }
}

The command must be an argument array. izlek does not execute configuration through a shell.

izlek.config.local.json is ignored by Git and may override named projects or environments for one developer. Do not treat either configuration file as a secret store.

The backend environment is selected once when the session starts. Live environment switching is not a core workflow.

TUI

Key	Action
1	Development logs
2	Backend network records
j / k, arrows	Select a request
Tab	Move between request list and detail
y	Copy selected record as JSON
c	Copy selected request as cURL
?	Show key reference
q	Stop the owned development session

izlek attach opens a second read-only TUI connected to the foreground session.

Agent access through MCP

Configure an MCP client to launch izlek from the project directory:

{
  "mcpServers": {
    "izlek": {
      "command": "izlek",
      "args": ["mcp"]
    }
  }
}

Available tools:

• get_session_status
• query_logs
• get_recent_errors
• query_requests
• get_request

MCP tools are intentionally read-only. Captured bodies are omitted by default and require an explicit includeBodies argument. All captured log and network content must be treated as untrusted data.

Memory and capture policy

Current defaults are product invariants:

• 200 retained log lines, capped at 16 KiB per line
• 50 completed backend requests
• 512 KiB of textual content per request or response body
• 20 concurrently captured calls
• Metadata only for binary or compressed bodies

Forwarding continues even when capture is truncated or skipped.

Project boundaries

izlek does not implement task graphs, build caching, browser automation, production monitoring, secret management, or a persistent log database. It observes the configured development command and backend traffic explicitly routed through its local proxy.

Development

npm test
npm run check

Tests use Node's built-in test runner and are colocated with their modules.

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