Debugging

Debugging Skill

Debug web applications, Node.js backends, and running Python processes using console inspection, network analysis, and non-blocking code debugging with tracepoints, logpoints, and exception monitoring.

When to Use

This skill activates when:

• User reports a bug or error on a web page or backend
• User asks to debug JavaScript (frontend or Node.js) or Python (a running process)
• User wants to inspect API calls or network requests
• User needs to troubleshoot page loading or API handler issues
• User mentions console errors or warnings
• User wants to debug without breakpoints
• User needs to trace function calls or monitor variables
• User needs to diagnose a Python deadlock, GIL contention, or hung threads

Capabilities

Console Inspection

ironbee-browser-devtools-cli o11y get-console-messages
ironbee-browser-devtools-cli o11y get-console-messages --type warning
ironbee-browser-devtools-cli --json o11y get-console-messages --type error

Network Analysis

ironbee-browser-devtools-cli o11y get-http-requests
ironbee-browser-devtools-cli --json o11y get-http-requests --resource-type fetch
ironbee-browser-devtools-cli --json o11y get-http-requests --status '{"min":400}'

Tracepoints (Non-Blocking)

ironbee-browser-devtools-cli debug put-tracepoint --url-pattern "app.js" --line-number 42
ironbee-browser-devtools-cli debug list-probes --types tracepoint
ironbee-browser-devtools-cli debug remove-probe --type tracepoint --id <probe-id>
ironbee-browser-devtools-cli debug clear-probes --types tracepoint

Logpoints

ironbee-browser-devtools-cli debug put-logpoint --url-pattern "app.js" --line-number 50 --log-expression "user.id"
ironbee-browser-devtools-cli debug list-probes --types logpoint
ironbee-browser-devtools-cli debug remove-probe --type logpoint --id <probe-id>
ironbee-browser-devtools-cli debug clear-probes --types logpoint

Exception Monitoring

ironbee-browser-devtools-cli debug put-exceptionpoint --state uncaught
ironbee-browser-devtools-cli debug put-exceptionpoint --state all

Watch Expressions

ironbee-browser-devtools-cli debug add-watch --expression "this"
ironbee-browser-devtools-cli debug add-watch --expression "user.id"
ironbee-browser-devtools-cli debug list-probes --types watch
ironbee-browser-devtools-cli debug remove-probe --type watch --id <probe-id>
ironbee-browser-devtools-cli debug clear-probes --types watches

Retrieve and Clear Snapshots (Unified)

ironbee-browser-devtools-cli --json debug get-probe-snapshots
ironbee-browser-devtools-cli --json debug get-probe-snapshots --types tracepoint,logpoint,exceptionpoint
ironbee-browser-devtools-cli --json debug get-probe-snapshots --probe-id "tp_abc" --from-sequence 0
ironbee-browser-devtools-cli debug clear-probe-snapshots
ironbee-browser-devtools-cli debug clear-probe-snapshots --types tracepoint --probe-id "tp_abc"

Node.js Backend Debugging (ironbee-node-devtools-cli)

For debugging Node.js API servers, backends, or scripts:

# 1. Connect to process (by PID, name, or Docker)
ironbee-node-devtools-cli --session-id backend-debug debug connect --pid 12345
ironbee-node-devtools-cli --session-id backend-debug debug connect --process-name "server.js"

# 2. Tracepoint on route handler or service
ironbee-node-devtools-cli --session-id backend-debug debug put-tracepoint \
  --url-pattern "routes/api.ts" \
  --line-number 42

# 3. Exception monitoring
ironbee-node-devtools-cli --session-id backend-debug debug put-exceptionpoint --state uncaught

# 4. Console logs from Node process
ironbee-node-devtools-cli --session-id backend-debug --json debug get-logs
ironbee-node-devtools-cli --session-id backend-debug --json debug get-logs --search "error"

# 5. Retrieve snapshots (after triggering the code path)
ironbee-node-devtools-cli --session-id backend-debug --json debug get-probe-snapshots
ironbee-node-devtools-cli --session-id backend-debug --json debug get-probe-snapshots --types tracepoint,exceptionpoint

# 6. Status and cleanup
ironbee-node-devtools-cli --session-id backend-debug debug status
ironbee-node-devtools-cli debug disconnect

urlPattern in Node context matches script file paths (e.g., server.js, routes/users.ts). See ironbee-node-devtools-cli skill for full reference.

Python Backend Debugging (ironbee-python-devtools-cli)

For debugging a running Python process (API server, worker, script) via debugpy — the target's Python env must have debugpy installed:

# 1. Connect (already-listening debugpy, PID injection, or process name)
ironbee-python-devtools-cli --session-id py-debug debug connect --host 127.0.0.1 --debugpy-port 5678
ironbee-python-devtools-cli --session-id py-debug debug connect --pid 12345
ironbee-python-devtools-cli --session-id py-debug debug connect --process-name "app.py"

# 2. Tracepoint on a handler (python probes use --file/--line, not --url-pattern/--line-number)
ironbee-python-devtools-cli --session-id py-debug debug put-tracepoint --file "routes/users.py" --line 25

# 3. Exception monitoring
ironbee-python-devtools-cli --session-id py-debug debug put-exceptionpoint --state uncaught

# 4. Process stdout/stderr logs
ironbee-python-devtools-cli --session-id py-debug --json debug get-logs --type error

# 5. Deadlock / hung-thread diagnosis: snapshot EVERY thread's stack at once
ironbee-python-devtools-cli --session-id py-debug --json debug dump-threads --include-locals

# 6. Retrieve snapshots, then clean up
ironbee-python-devtools-cli --session-id py-debug --json debug get-probe-snapshots
ironbee-python-devtools-cli --session-id py-debug debug disconnect

See ironbee-python-devtools-cli skill for full reference.

Error Investigation

ironbee-browser-devtools-cli content take-screenshot --name "error-state"
ironbee-browser-devtools-cli content get-as-html --selector ".error-container"

Basic Debugging Workflow

1. Reproduce: Navigate to the problematic page
2. Capture: Take screenshot of current state
3. Inspect Console: Check for JavaScript errors
4. Analyze Network: Look for failed requests
5. Investigate: Run diagnostic JavaScript
6. Document: Summarize findings with evidence

# Quick debug workflow
ironbee-browser-devtools-cli navigation go-to --url "https://example.com"
ironbee-browser-devtools-cli content take-screenshot --name "initial"
ironbee-browser-devtools-cli --json o11y get-console-messages --type warning
ironbee-browser-devtools-cli --json o11y get-http-requests --status '{"min":400}'

Advanced Debugging Workflow (Non-Blocking)

1. Set Up Probes

SESSION="--session-id debug-session"

# Navigate to app
ironbee-browser-devtools-cli $SESSION navigation go-to --url "http://localhost:3000"

# Tracepoint on a function
ironbee-browser-devtools-cli $SESSION debug put-tracepoint \
  --url-pattern "app.js" \
  --line-number 42

# Exception monitoring
ironbee-browser-devtools-cli $SESSION debug put-exceptionpoint --state uncaught

2. Add Watch Expressions

ironbee-browser-devtools-cli $SESSION debug add-watch --expression "this"
ironbee-browser-devtools-cli $SESSION debug add-watch --expression "user.id"

3. Interact with Application

ironbee-browser-devtools-cli $SESSION interaction click --selector "#submit-btn"
ironbee-browser-devtools-cli $SESSION sync wait-for-network-idle

4. Retrieve Snapshots

ironbee-browser-devtools-cli $SESSION --json debug get-probe-snapshots
ironbee-browser-devtools-cli $SESSION --json debug get-probe-snapshots --types tracepoint,exceptionpoint
ironbee-browser-devtools-cli $SESSION --json debug get-probe-snapshots --from-sequence 0

5. Clean Up

ironbee-browser-devtools-cli $SESSION debug clear-probes
ironbee-browser-devtools-cli $SESSION debug clear-probe-snapshots
ironbee-browser-devtools-cli session delete debug-session

Probe Types Summary

Probe	Purpose	Output	CLI
Tracepoint	Function calls	Stack, locals, watches	ironbee-browser-devtools-cli, ironbee-node-devtools-cli, ironbee-python-devtools-cli
Logpoint	Expression values	Evaluated result	all three
Exceptionpoint	Error catching	Error, stack trace	all three
Watch	Per-tracepoint expressions	watchResults in snapshot	list/remove via list-probes, remove-probe, clear-probes
Thread dump	Deadlock / GIL / hung-thread diagnosis	Every thread's stack	ironbee-python-devtools-cli only (debug dump-threads)

Best Practices

1. Choose the right CLI: Use ironbee-browser-devtools-cli for frontend/page debugging; use ironbee-node-devtools-cli for Node.js backend/API debugging; use ironbee-python-devtools-cli for running Python processes (probes take --file/--line there, and the target needs debugpy installed)
2. Always check console for errors first
3. Filter network requests to relevant endpoints
4. Take screenshots before and after actions (browser)
5. Use source maps for minified/bundled code
6. Start with exceptions to catch errors first
7. Use logpoints for lightweight monitoring
8. Poll snapshots with --from-sequence for efficiency
9. Clear probes when done to avoid overhead
10. Document reproduction steps clearly