Debugger Integration

CodeBuddy can interact with any debugger through the Debug Adapter Protocol (DAP). When a debug session is active, the agent gains tools to inspect threads, walk stack frames, evaluate expressions, and control execution — all without leaving the chat.

Prerequisites

Start a debug session normally (F5 or Run and Debug). CodeBuddy detects the active vscode.DebugSession automatically. Any debugger that implements DAP works: Node.js, Python, Go, Java, C++, Rust, etc.

Agent tools

The debugger tool exposes these actions:

Action	What it does
threads	Lists all threads in the active debug session
stackTrace	Returns up to 20 stack frames for a given thread
scopes	Lists scopes (local, global, closure) for a stack frame
variables	Reads variables within a scope (by variablesReference)
evaluate	Evaluates an expression in the REPL context of an optional frame
stepOver	Steps over the current line (DAP next)
stepInto	Steps into the current function call
stepOut	Steps out of the current function
continue	Resumes execution until the next breakpoint
pause	Pauses a running thread

Example workflow

You: "The function returns null instead of the expected array. Debug it."

Agent: [thinks] I'll inspect the active debug session to find the issue.
       [debugger:threads] → Thread 1 (paused at breakpoint)
       [debugger:stackTrace threadId=1] → Frame 0: processItems() at src/handler.ts:42
       [debugger:scopes frameId=0] → Local scope (ref: 1001)
       [debugger:variables ref=1001] → items = undefined, config = {...}

       The issue is that `items` is undefined at line 42. The function
       `fetchItems()` on line 38 likely returned undefined instead of an array.
       [debugger:evaluate expression="typeof fetchItems" frameId=0] → "function"
       [debugger:evaluate expression="fetchItems()" frameId=0] → undefined

       The root cause is `fetchItems()` returns nothing when the cache is empty.

Limitations

• Requires an active debug session — the agent cannot start one
• DAP custom requests depend on the debug adapter implementation; some adapters may not support all actions
• The evaluate action runs in REPL context, which may have side effects
• Stack trace depth defaults to 20 frames; pass levels parameter to increase