crash_sight

Production-Grade Debugging Engine · A zero-dependency runtime exception interceptor that hijacks sys.excepthook to maximize Developer Experience (DX).

crash_sight is a post-mortem debugging engine for Python 3.8+ that operates at the runtime interceptor level. When an unhandled exception escapes your application, crash_sight captures the precise execution context, scrubs sensitive data, generates a beautifully formatted ANSI terminal report, exports a clean Markdown log, and drops you into an interactive REPL at the exact crash site — all with zero external dependencies.

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Core Pillars

crash_sight's architecture is composed of five tightly integrated modules, each responsible for a critical stage of the post-mortem pipeline:

Module	Responsibility
Core Interceptor (crash_sight.core.interceptor)	Registers a global hook on sys.excepthook, traverses the stack frame window to the deepest frame, and orchestrates the entire pipeline.
Security Data Scrubber (crash_sight.security.masker)	Scans local and global variables using case-insensitive regex pattern matching, replacing sensitive values (e.g., password, secret, token, apiKey, credential) with "******** (SECURED)". Supports nested dictionaries, lists, and tuples with infinite recursion depth.
Terminal Formatter (crash_sight.formatter.terminal)	Renders a visually stunning ANSI-colored crash report complete with source code context, variable dump, and precise arrow markers — all using only standard library linecache.
Post-Mortem REPL (crash_sight.repl.console)	Launches an interactive Python shell (code.InteractiveConsole) injected with the exact masked locals and globals from the crash frame, allowing real-time forensic inspection.
Markdown Exporter (crash_sight.exporter.markdown)	Strips ANSI color codes and writes a pristine Markdown version of the crash report to crash_report_[YYYYMMDD_HHMMSS].md for logging, CI/CD, or team sharing.

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Installation

Install crash_sight locally in development/editable mode from the project root:

pip install -e .

Zero Dependencies Guarantee – pip freeze will show zero additional packages. crash_sight uses only Python Standard Library modules: sys, inspect, linecache, code, os, re, datetime, typing.

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Quick Start

Create a file called test_crash.py with the following content:

import crash_sight

crash_sight.install()

def risky_function(user_input):
    user_password = "sup3rS3cr3t!"
    apiKey = "AIzaSyD-abc123def456"
    my_secret_token = "ghp_xxxxxxxxxxxx"
    ratio = 100 / user_input  # will trigger ZeroDivisionError when user_input = 0

risky_function(0)

Then run it:

python test_crash.py

That's it — two lines to activate crash_sight. The rest is automatic.

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Aesthetic Terminal Preview

When you run the example above, crash_sight will print a report like this to stderr:

🔍 crash_sight — Post-Mortem Report
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

⚡ ZeroDivisionError: division by zero

📍 Location:
   📄 File: /path/to/test_crash.py
   🔧 Function: risky_function
   ⏰ Line: 8

📄 Code Context:
   5  | def risky_function(user_input):
   6  |     user_password = "sup3rS3cr3t!"
   7  |     apiKey = "AIzaSyD-abc123def456"
   8  ───> ratio = 100 / user_input
   9  | 
  10  | risky_function(0)

🔍 Local Variables (Masked):
   user_input        = 0
   user_password     = ******** (SECURED)
   apiKey            = ******** (SECURED)
   my_secret_token   = ******** (SECURED)
   ratio             = <not defined>

📁 Report saved to: crash_report_20250320_143022.md

💻 Opening interactive REPL at crash site...
   Type 'exit()' or 'quit()' to return to the shell.

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Security & Masking Specifications

The security engine (crash_sight.security.masker) applies a deterministic, pattern-based masking algorithm with the following rules:

Pattern Matching (Case-Insensitive)

Any variable key containing any of these substrings (case-insensitive) will have its value replaced:

Keyword	Example Keys That Trigger Masking
password	password, userPassword, PASSWORD, passwords_list
secret	secret, my_secret_token, SECRET_KEY, secret_answer
token	token, api_token, TOKEN, auth_tokens
apikey	apiKey, API_KEY, apikey, api_key_v2
credential	credential, credentials, CREDENTIALS

Recursive Scrubbing — Full Nested Support

Masking is applied recursively to arbitrary-depth data structures:

• Nested dictionaries: {"db": {"password": "s3cr3t"}} → {"db": {"password": "******** (SECURED)"}}
• Lists of dictionaries: [{"apiKey": "xyz"}, {"other": 42}] → [{"apiKey": "******** (SECURED)"}, {"other": 42}]
• Tuples: ("user", {"token": "abc"}) → ("user", {"token": "******** (SECURED)"})
• Mixed nesting is fully supported.

False-Positive Guard

Variables whose keys contain certain "safe" substrings are intelligently bypassed:

• not_secret → NOT masked (contains "secret" but guarded)
• public_token_id → NOT masked (contains "token" but guarded)

Built-in exception list: not_secret, not_password, public_token, non_credential, and equivalents are safely ignored.

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Python 3.14 Compatibility Note

crash_sight is fully compliant with PEP 667 (introduced in Python 3.13, standard in 3.14). The extract_deepest_context() function explicitly converts frame.f_locals and frame.f_globals to standard dict objects using dict() constructor, ensuring seamless compatibility with Python 3.13+ where FrameLocalsProxy is returned instead of a plain dictionary.

This safeguard is encapsulated in the core interceptor:

# In Python 3.13+, frame.f_locals returns FrameLocalsProxy, not a plain dict
f_locals: Dict[str, Any] = dict(frame.f_locals)
f_globals: Dict[str, Any] = dict(frame.f_globals)

Tested and verified across Python 3.8 through 3.14-pre release.

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Testing

crash_sight ships with a comprehensive test suite (90+ tests covering unit, integration, and edge-case scenarios). Run the full suite with:

python -m unittest discover -s tests -p "test_*.py" -v

Test categories include:

• Core interceptor installation/idempotency/uninstallation
• Deepest frame extraction (including chain tracebacks)
• Security masker — pattern matching, nested structures, false-positive guard
• Terminal formatter (ANSI rendering, code context windows)
• Markdown exporter (cleaning, naming conventions)
• REPL initialization and context injection
• Cross-version compatibility (Python 3.8–3.14)

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Development & Contributing

1. Clone the repository:

   git clone https://github.com/annaqibz01/crash_sight.git
   cd crash_sight

2. Install in editable mode:

   pip install -e .

3. Run the tests:

   python -m unittest discover -s tests -p "test_*.py" -v

4. Submit a pull request or open an issue on GitHub Issues.

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License

Distributed under the MIT License. See LICENSE for more information.

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crash_sight — Zero-dependency debugging. Precision post-mortem. Maximum DX.