Blackbox

LLM-friendly Python debugger with structured, readable output and comprehensive instrumentation.

When Python code crashes, blackbox provides clean, well-organized output that's easy for LLMs (and humans) to understand and act on. It captures not just the crash, but the full context: I/O operations, resource usage, memory allocations, and more.

Installation

pip install jaymd96-blackbox

For full instrumentation features, install optional dependencies:

pip install jaymd96-blackbox[full]
# Or individually:
pip install psutil wrapt  # for resource monitoring and HTTP tracking

Usage

# Run with crash handling and full instrumentation (default)
python -m blackbox script.py

# Run with execution tracing
python -m blackbox --trace script.py

# Focus on specific package (hide stdlib/frameworks)
python -m blackbox --focus mypackage script.py

# Set timeout for hang detection
python -m blackbox --timeout 30 script.py

# Disable instrumentation (just crash handling)
python -m blackbox --no-instrumentation script.py

What You Get

On Crash - Full Context

══════════════════════════════════════════════════════════════════════
CRASH: KeyError
══════════════════════════════════════════════════════════════════════

Message: 'missing_key'
Location: mypackage/api.py:67 in process_data()

──────────────────────────────────────────────────────────────────────
CALL CHAIN
──────────────────────────────────────────────────────────────────────

    <module> → main → process_data

    [django: 12 frames hidden]
    [stdlib: 8 frames hidden]

──────────────────────────────────────────────────────────────────────
FRAME 1: mypackage/api.py:67  ← CRASH HERE
──────────────────────────────────────────────────────────────────────

Function: process_data(data)

   65│
   66│     # Access a key that doesn't exist
>> 67│     result = data['missing_key']
   68│     return result

Arguments:
    data         = {'status': 'ok', 'items': [1, 2, 3]}

Locals:
    large_list   = list([10000 items])

──────────────────────────────────────────────────────────────────────
I/O TRAIL (recent activity)
──────────────────────────────────────────────────────────────────────

  [HTTP]
    • GET https://api.example.com/data → 200 (45.2ms)
    • POST https://api.example.com/submit → 201 (123.5ms)

  [DB]
    • SELECT: SELECT * FROM users WHERE id = ? (2.3ms)
      query_type=SELECT, table=USERS

  [FILE]
    • open(config/settings.yaml, mode=r)
    • open(data/cache.json, mode=w)

  [CONFIG]
    • ENV[API_KEY] = <REDACTED>
    • ENV[DEBUG] → not set

──────────────────────────────────────────────────────────────────────
RESOURCE STATE (at crash)
──────────────────────────────────────────────────────────────────────

  Memory:
    RSS:     62.5 MB
    VMS:     415.2 GB
    Percent: 0.4%

  CPU: 12.3%

  Threads: 4

  Open Files (3):
    • /path/to/data.db
    • /path/to/log.txt
    • /tmp/cache.json

  Network Connections (1):
    • 127.0.0.1:5432 → 10.0.0.1:5432 (ESTABLISHED)

──────────────────────────────────────────────────────────────────────
TOP MEMORY ALLOCATIONS
──────────────────────────────────────────────────────────────────────

    391.6 KB  mypackage/api.py:64  (9872 allocs)
     28.8 KB  lib/python3.13/linecache.py:146  (358 allocs)
     10.0 KB  <frozen runpy>:259  (130 allocs)

──────────────────────────────────────────────────────────────────────
SLOW OPERATIONS
──────────────────────────────────────────────────────────────────────

       123.5ms  POST https://api.example.com/submit [http] ⚠ SLOW

──────────────────────────────────────────────────────────────────────
ANALYSIS
──────────────────────────────────────────────────────────────────────

Problem: Key 'missing_key' not found in 'data'
Available keys: ['status', 'items']

══════════════════════════════════════════════════════════════════════

With Execution Tracing

══════════════════════════════════════════════════════════════════════
EXECUTION TRACE
══════════════════════════════════════════════════════════════════════

├─→ process(items=[1, 2, 3])
│   ├─→ validate(items=[1, 2, 3])
│   │     returned True
│   ├─→ transform(items=[1, 2, 3])
│   │     returned [2, 4, 6]
│   └─ returned [2, 4, 6]

──────────────────────────────────────────────────────────────────────
SUMMARY
──────────────────────────────────────────────────────────────────────

Duration    : 0.003s
Calls       : 3
Max depth   : 2

══════════════════════════════════════════════════════════════════════

Instrumentation Features

Blackbox captures comprehensive runtime information:

Options

Programmatic Usage

from blackbox import install_crash_handler
from blackbox.instruments import install_all_hooks

# Install instrumentation first
install_all_hooks()

# Install as global exception handler
install_crash_handler(focus=['mypackage'])

# Now any uncaught exception will produce rich output

Custom Breadcrumbs

from blackbox.collector import get_collector, BreadcrumbType

collector = get_collector()

# Add custom breadcrumb
collector.add_breadcrumb(
    type=BreadcrumbType.CUSTOM,
    category="business_logic",
    message="Processing order #12345",
    data={"order_id": 12345, "items": 3},
)

Manual Timing

from blackbox.instruments.timing import timed, timed_block

# Decorator
@timed("critical_operation")
def my_function():
    pass

# Context manager
with timed_block("data_processing"):
    process_data()

Why Blackbox?

Standard Python tracebacks are noisy and hard to parse:

• Mixed with framework internals
• Missing local variable values
• No context about what happened before the crash
• No analysis or hints
• Difficult for LLMs to process

Blackbox provides:

• Clean visual hierarchy - Clear sections and separators
• Noise filtering - Collapse stdlib and frameworks
• Local variables - See what values caused the crash
• Code context - Surrounding lines for context
• I/O trail - What happened leading up to the crash
• Resource state - Memory, CPU, files, connections at crash time
• Memory analysis - Where allocations are happening
• Analysis hints - Automatic problem identification
• Structured format - Easy for LLMs to parse and reason about