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082025AI / Backend

PromptTune

A prompt optimisation platform that converts a raw prompt into a paste-ready system prompt with rationale and a self-evaluation checklist, using RAG over a curated prompt-engineering corpus.

Period
Nov 2025
Context
Buildables

The problem

Prompt advice is scattered across guides and papers, and iteration usually happens in a scratch file with nothing retained. The design answer was to make the improvement itself retrieval-grounded - the optimiser cites a real corpus rather than the model's own habits - and to parse the output deterministically from tag-delimited fields, so the prompt, its rationale and its checklist are separable data rather than prose to re-read.

What I built

  1. Implemented a RAG layer ingesting Markdown guides, arXiv papers and PDFs into a 384-dimension Pinecone serverless index, with recursive 1,000-character chunking, 200-character overlap and batched upserts using all-MiniLM-L6-v2 embeddings.
  2. Designed a structured meta-prompting engine applying a five-step Task–Context–References–Evaluate–Iterate framework, with tag-delimited LLM output parsed deterministically into optimised prompt, rationale and checklist fields.
  3. Built a persona system with eight seeded role templates and user-owned custom personas, composing persona instructions into system context for both optimisation and chat, with per-user ownership scoping and an active-persona default.
  4. Implemented HS256 JWT authentication with PBKDF2-SHA256 password hashing over a six-table SQLAlchemy/PostgreSQL schema covering users, profiles, personas, prompts, chat sessions and analytics, with full CRUD REST APIs for a searchable prompt library.
  5. Added a windowed in-memory chat session store retaining the last 20 messages per session, enabling an optimise → test → refine loop against the generated system prompt.

Stack

PythonFastAPIUvicornPydanticSQLAlchemyPostgreSQLAlembicpython-josePasslibLangChainGroq API (Llama 3.3 70B)Pineconesentence-transformersPyPDFUnstructuredReact 18ViteReact RouterAxios

Skills applied

  • RAG pipeline design
  • Vector search and embedding models
  • Meta-prompt engineering
  • Structured LLM output parsing
  • Relational schema design
  • JWT authentication and password hashing
  • Document ingestion and chunking strategy
  • REST API development
  • Persona-based prompt testing
  • Frontend state management with React Context