How I Built RepoSéance: A Local-First AI Ghost Hunter That Resurrects Abandoned Codebases

Hacktoberfest Open-Source AI Challenge: Ghost in the Machine Submission 👻🌼

This is a submission for the Hacktoberfest Open-Source AI Challenge Week 4: Ghost in the Machine

Every developer knows the eerie feeling: you stumble across a dusty GitHub repository from 4 years ago that solved the exact esoteric problem or algorithmic challenge you are wrestling with today.

Sending a proprietary or private codebase to cloud AI APIs poses massive confidentiality risks and burns expensive tokens. And what happens when you need to inspect code on an offline plane or in a high-security environment?

I built RepoSéance to bring these ghost codebases back to life.

RepoSéance is a local-first, privacy-respecting software archaeology companion. You provide a local directory path or upload a ZIP archive of any neglected project, and RepoSéance conducts a digital séance:

Local Repository / ZIP ──> Safe Scanner & Secret Redactor ──> Deterministic AST & Git Parser │ ┌───────────────────────────────────────┴───────────────────────────────────────┐ ▼ ▼ Local Embeddings (Nomic / BGE) Git History & TODO Extractor │ │ ▼ │ Local Vector Index │ │ │ └───────────────────────────────┬───────────────────────────────────────────────┘ ▼ Evidence Retrieval & Chunk Citations │ ┌───────────────────────────────┴───────────────────────────────┐ ▼ ▼ Ollama Runtime (Qwen2.5 / Gemma 2) Offline Deterministic Autopsy Fallback │ │ └───────────────────────────────┬───────────────────────────────┘ ▼ Digital Séance Dashboard & Ghost Chat - Project Autopsy & Architecture - Evidence-Cited Q&A - Prioritized Revival Roadmap - Exportable Markdown Dossier Enter fullscreen mode Exit fullscreen mode Demo RepoSéance embraces a futuristic, haunted-terminal aesthetic: sleek dark charcoal backgrounds, spectral violet ( #9d4edd ) and muted cyan accents, glassmorphic cards, and crisp monospace typography.

The application is organized into 5 focused modules:

Select a local repository or drag in a ZIP archive. RepoSéance validates the path, respects.gitignore, redacts detected credentials, and extracts Git commit timelines in seconds:

The local AI reconstructs high-level module relationships, flags undocumented entry points, and catalogs uncompleted TODO s:

Ask technical questions about esoteric functions or forgotten data pipelines. The Ghost answers with technical rigor and explicit file citations:

Filter by priority and track tasks as you bring the project back to life:

RepoSéance requires zero external API keys and runs completely on standard laptop hardware:

# 1. Clone the repository git clone https://github.com/Vaibhav-1819/RepoS-ance.git cd RepoS-ance # 2. Set up the Python backend cd backend python -m venv venv # Windows:. \v env \S cripts \a ctivate # Linux/macOS: source venv/bin/activate pip install -r requirements.txt # 3. (Optional) Start Ollama for local LLM inference ollama run qwen2.5-coder:7b # Or smaller models for lightweight laptops: # ollama run qwen2.5:3b or ollama run gemma2:2b # 4.

Start the backend server uvicorn main:app --reload --port 8000 # 5. In a new terminal, launch the frontend cd../frontend npm install npm run dev Enter fullscreen mode Exit fullscreen mode Note: If Ollama is not running, RepoSéance automatically activates its built-in deterministic heuristic engine, providing complete structural autopsies, Git analyses, and TODO inventories without failing.

The complete codebase is 100% open-source under the MIT license:

Processing unfamiliar codebases with local open-weight models presents two major hurdles: context window limits and hallucination risk.

Feeding 50,000 lines of raw code into a local 3B or 7B model causes memory thrashing, high latency, and severe hallucinations. RepoSéance overcomes this with a Bounded Evidence Pipeline:

Because RepoSéance is built to inspect untrusted, abandoned repositories, security is a non-negotiable prerequisite:

Open-source software powers the modern digital economy, but thousands of promising repositories are abandoned each year due to maintainer burnout, corporate shifts, or life changes.

To put RepoSéance to the test, I summoned a 3-year-old abandoned Python CLI audio transcriber repository that had been archived on GitHub with the commit message "pausing for now".

What RepoSéance unearthed in under 20 seconds:

I would love to hear your thoughts and experiences:

If you find this project valuable, please give it a star on GitHub and share your thoughts below! I'll be in the comments answering questions and discussing software archaeology.