How do I install Debugium?

Copy the stdio config for Cursor, Claude Desktop, Claude Code, or VS Code on this page. It uses the publisher's install, not a PlugMCP proxy.

Does Debugium need an API key?

No required environment variable is listed on this record.

What transport does Debugium use?

Debugium runs locally over stdio.

When was Debugium last checked?

Last checked 2026-11-08. AI-driven live debugger with MCP bridge for Python, JS, TS, Rust, Java, C/C++

Debugium MCP server

Debugium

A multi-language debugger with a real-time web UI and LLM integration via MCP.

Debug Python, JavaScript, TypeScript, C, C++, Rust, Java, Scala, and WebAssembly programs from your browser — with AI-driven analysis through the Model Context Protocol.

Debugium UI — paused at a breakpoint in target_python.py with variables, call stack, breakpoints, watch, timeline, and console panels

Features

Web UI

Real-time web UI — source viewer, breakpoints, variables (recursive expansion), call stack, console, timeline, watch expressions, findings — all updated live via WebSocket
Multi-tab source viewer — open multiple files, click stack frames to navigate
Variable search — filter variables by name with recursive expansion
Changed-variable highlighting — variables that changed since last stop shown in orange
Thread selector — switch between threads in multi-threaded programs
Panel collapse & resize — drag to resize, toggle to collapse; Slim / Standard / Full layout presets
Dark / light mode toggle
Auto-reconnect — UI reconnects after a dropped WebSocket, with visual status indicator
Keyboard shortcuts — F5 continue, F10 step over, F11 step in, Shift+F11 step out, Ctrl/Cmd+D dark mode
Button animations — in-flight spinner and completion flash for debug commands

Debugging

Multi-language — Python (debugpy), Node.js/TypeScript (js-debug), C/C++/Rust (lldb-dap), Java (java-debug), Scala (Metals), WebAssembly (lldb-dap), or any DAP adapter via dap.json
Comprehensive DAP coverage — 35+ DAP requests: breakpoints, stepping, goto, memory read/write, disassembly, and more
Breakpoints — conditional, logpoints, hit-count, function, data (watchpoints), exception, run-to-cursor (continue_until)
Multi-session — debug multiple programs simultaneously, with child session routing (js-debug)
Remote debugging — attach to debugpy, JDWP, or Node inspector running on another machine or container

LLM / MCP Integration

64 MCP tools — the full debug session exposed to Claude or any LLM
Capability-gated tools — tools automatically shown/hidden based on adapter capabilities
Compound tools — get_debug_context (orient in one call), step_until, step_until_change, run_until_exception, explain_exception, get_call_tree, compare_snapshots, find_first_change
Execution timeline — every stop recorded with changed variables and stack summary
Watch expressions — evaluated automatically at every breakpoint, manageable by LLM or UI
Annotations & findings — pin notes to source lines, record conclusions visible in the UI
Session export/import — save and restore debugging knowledge across sessions

CLI Control

Full CLI — 13 subcommands to drive sessions from a second terminal without the web UI
Auto-discovery — port file at ~/.debugium/port, session logs in ~/.debugium/sessions/

Install

Claude Code Plugin (recommended)

/plugin marketplace add Algiras/debugium
/plugin install debugium@debugium

Then add to your project's .mcp.json (see MCP Tools below).

macOS / Linux binary

curl -fsSL https://raw.githubusercontent.com/Algiras/debugium/main/install.sh | bash

From source

# Prerequisites: Rust stable + wasm-pack
cargo install wasm-pack

# Build UI
wasm-pack build crates/debugium-ui --target web --out-dir pkg
cp crates/debugium-ui/pkg/cm_init.js         crates/debugium-ui/dist/pkg/
cp crates/debugium-ui/pkg/debugium_ui.js      crates/debugium-ui/dist/pkg/
cp crates/debugium-ui/pkg/debugium_ui_bg.wasm crates/debugium-ui/dist/pkg/

# Build & install server
cargo install --path crates/debugium-server

Usage

Debug a Python file

debugium launch my_script.py --adapter python

Debug a Node.js / TypeScript file

debugium launch app.js --adapter node
debugium launch app.ts --adapter typescript

Debug C / C++ / Rust

# C or C++ (compile with -g for debug info)
cc -g -O0 main.c -o main && debugium launch ./main --adapter lldb
c++ -g -O0 main.cpp -o main && debugium launch ./main --adapter lldb

# Rust
cargo build && debugium launch target/debug/my_binary --adapter lldb

Debug Java / Scala

# Java (requires microsoft/java-debug adapter)
debugium launch MainClass --adapter java

# Scala (connect to a running Metals DAP server)
debugium launch build-target --adapter metals
debugium launch build-target --adapter metals:5005  # custom port

Attach to a running process (remote debugging)

# Python (debugpy listening on port 5678)
debugium attach --port 5678 --adapter python

# Java (JDWP on port 5005)
debugium attach --port 5005 --adapter java

# Node.js (inspector on port 9229)
debugium attach --port 9229 --adapter node

Or via MCP: attach_session(port=5678, adapter="python", breakpoints=["/path/app.py:42"])

Use a custom adapter via dap.json

# Create a dap.json (see dap.json.example) then:
debugium launch my_program --config ./dap.json

# Or place dap.json in cwd / .debugium/ for auto-discovery:
debugium launch my_program   # finds ./dap.json automatically

Set initial breakpoints

debugium launch my_script.py --adapter python \
  --breakpoint /abs/path/my_script.py:42 \
  --breakpoint /abs/path/helpers.py:15

Enable LLM / MCP integration

Add a .mcp.json to your project root (Claude Code picks this up automatically):

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

Then launch the session normally — the MCP server connects to whichever port is active:

debugium launch my_script.py --adapter python --breakpoint /abs/path/my_script.py:42

Claude Code will now have access to all Debugium MCP tools. See CLAUDE.md for the recommended workflow and SKILL.md for the full tool reference.

CLI Control Commands

Once a session is running (debugium launch …), you can drive it from a second terminal — or from an LLM agent — without touching the web UI.

Port is auto-discovered from ~/.debugium/port; override with --port.

Global flags (all subcommands)

Flag	Default	Description
`--port PORT`	`~/.debugium/port`	Server port to connect to
`--session ID`	`default`	Session to target
`--json`	off	Print raw JSON instead of human-readable output

Inspection

debugium sessions                  # list active sessions
debugium threads                   # list threads
debugium stack                     # show call stack
debugium vars                      # show local variables (auto-resolves top frame)
debugium vars --frame-id 2         # show variables for a specific frame
debugium eval "len(fibs)"          # evaluate expression in top frame
debugium eval "x + 1" --frame-id 2
debugium source path/to/file.py    # print full source file
debugium source path/to/file.py --line 43  # windowed ±10 lines with → marker
debugium context                   # full snapshot: paused-at, stack, locals, source, breakpoints
debugium context --compact         # same but truncated (3 frames, 10 vars)

Breakpoints

debugium bp set FILE:LINE [FILE:LINE …]   # set breakpoints (replaces existing in that file)
debugium bp list                          # list all breakpoints
debugium bp clear                         # clear all breakpoints

Execution control

debugium continue                  # resume execution
debugium step over                 # step over (next line)
debugium step in                   # step into a function call
debugium step out                  # step out of current function

UI annotations (visible in the web UI)

debugium annotate FILE:LINE "message" [--color info|warning|error]
debugium finding "message"         [--level  info|warning|error]

Example workflow

# Terminal A — start the session
debugium launch tests/target_python.py --adapter python \
  --breakpoint "$(pwd)/tests/target_python.py:43"

# Terminal B (or LLM agent) — inspect and drive it
debugium sessions
debugium stack
debugium vars
debugium eval "len(fibs)"
debugium bp set tests/target_python.py:49
debugium continue                  # runs to line 49
debugium vars
debugium step over
debugium context --json            # machine-readable snapshot
debugium annotate tests/target_python.py:43 "called here" --color info
debugium finding "fibs has 10 elements" --level info
debugium bp clear

MCP Tools

When connected via MCP, 64 tools are available. Key ones:

Category	Tools
Orient	`get_debug_context` ★ (paused location + locals + stack + source in one call)
Breakpoints	`set_breakpoint`, `set_breakpoints`, `set_logpoint`, `list_breakpoints`, `clear_breakpoints`, `set_function_breakpoints`, `set_exception_breakpoints`, `set_data_breakpoint`, `list_data_breakpoints`, `clear_data_breakpoints`, `breakpoint_locations`
Execution	`continue_execution`, `step_over`, `step_in`, `step_out`, `pause`, `goto`, `disconnect`, `terminate`, `restart`
Inspection	`get_stack_trace`, `get_scopes`, `get_variables`, `evaluate`, `get_threads`, `get_source`, `get_capabilities`, `loaded_sources`, `source_by_reference`, `step_in_targets`
Mutation	`set_variable`, `set_expression`
Output	`get_console_output`, `wait_for_output` (with `from_line` to avoid stale matches)
Memory	`read_memory`, `write_memory`, `disassemble` (native debugging)
History	`get_timeline`, `get_variable_history`, `compare_snapshots`, `find_first_change`
Annotations	`annotate`, `get_annotations`, `add_finding`, `get_findings`
Watches	`add_watch`, ,

Note: step_over, step_in, and step_out are blocking — they wait for the adapter to pause before returning. Safe to chain back-to-back without sleeps. continue_execution returns console_line_count for use with wait_for_output. Tools like read_memory, goto, and restart_frame only appear when the adapter supports them.

See SKILL.md for the full reference with input schemas.

Keyboard Shortcuts

Key	Action
`F5`	Continue
`F10`	Step Over
`F11`	Step Into
`Shift+F11`	Step Out
`Ctrl/⌘+D`	Toggle dark/light mode

Architecture

debugium-server (Rust + Axum)
├── DAP proxy     — spawns / attaches to debug adapters (debugpy, js-debug, lldb-dap, java-debug, Metals, custom)
├── HTTP API      — /state, /sessions, /annotations, /findings, /watches, /timeline
├── WebSocket     — broadcasts DAP events + enriched stop data (changed vars, timeline) to UI
├── MCP stdio     — JSON-RPC 2.0 server exposing 64 tools for LLM integration
├── CLI control   — 13 subcommands to drive sessions from a second terminal
└── ~/.debugium/  — port file, session logs (events.ndjson), debug log

debugium-ui (Leptos + WASM)
├── CodeMirror 6  — source viewer with breakpoint gutters, exec arrow, LLM annotations, multi-tab
├── Reactive panels — Variables, Stack, Breakpoints, Findings, Watch, Timeline, Console (18 components)
└── WebSocket     — receives events, sends DAP commands, auto-reconnects with status indicator

Supported Languages & Adapters

Language	`--adapter` flag	Prerequisite	Verified
Python	`python` / `debugpy`	`pip install debugpy`	✅
Node.js	`node` / `js`	js-debug (bundled or build from vscode-js-debug)	✅
TypeScript	`typescript` / `ts` / `tsx`	js-debug + `tsx` or `ts-node` in PATH	✅
C / C++	`lldb` / `codelldb`	`lldb-dap` (Xcode on macOS; `apt install lldb` on Linux)	✅
Rust	`lldb` / `rust`	`lldb-dap` + `cargo build`	✅
Java	`java` / `jvm`	microsoft/java-debug adapter JAR	✅
Scala	`metals` / `scala`	Running Metals DAP server	⚠️ (requires running Metals)
WebAssembly	`wasm`	`lldb-dap` (LLVM ≥16)	⚠️ (requires WASM-aware LLVM)
Any DAP adapter	`--config dap.json`	See `dap.json.example`	✅

Remote debugging

Connect to a DAP server running on another machine (or in a container):

{
  "adapterId": "debugpy",
  "request": "attach",
  "host": "192.168.1.100",
  "port": 5678,
  "pathMappings": [{ "localRoot": ".", "remoteRoot": "/app" }]
}

debugium launch app.py --config remote.json

License

MIT