Work

Backend · AI

Multi-tenant SaaS platform where businesses deploy autonomous AI receptionists and outbound calling agents over real PSTN phone lines.

• Architected a vertical-slice FastAPI + PostgreSQL backend (45+ models) with AWS Cognito JWT auth and SHA-256 audited superadmin impersonation.
• Built low-latency (<600ms) inbound & outbound call orchestration bridging Twilio PSTN trunks with Ultravox and Vapi WebRTC voice sessions.
• Implemented mid-call LLM tool execution for live calendar slot lookups, instant appointment booking, warm conference transfers with hold music, and real-time DND suppression.
• Engineered outbound campaign dialers with Twilio Asynchronous Machine Detection (DetectMessageEnd) for automated voicemail drops and GPT-4o post-call disposition & billing.

Open Source · AI · Backend

Open-source (Apache 2.0), AI-native knowledge workspace where conversations become interactive, branching 2D knowledge graphs with Hybrid RAG and autonomous agentic tools.

• Architected a modular monolith monorepo (FastAPI + Next.js 15 + PostgreSQL 16 with pgvector) and a strictly isolated packages/ai-core layer supporting Gemini 2.5, Claude 3.5, OpenAI GPT-4o, DeepSeek, and local Ollama.
• Built a Hybrid RAG engine combining dense HNSW vector similarity (pgvector) with PostgreSQL GIN full-text search via Reciprocal Rank Fusion (RRF) and multimodal PDF/Excel/CSV ingestion.
• Engineered a multi-turn SSE agentic tool loop with graph-native grounding tools (search_graph, traverse_branch_lineage, get_node_neighbors), live web grounding, and declarative markdown system skills.
• Implemented token-budgeted O(N) ancestor lineage traversal, DAG concept ontology & prerequisite gap analysis, node-linked active-recall flashcards, and an infinite 2D React Flow / Dagre canvas.

Backend · Integrations

Unified integration layer and omnichannel inbox synchronizing contacts, calendars, deals, payments, and messaging across 15+ external providers.

• Designed vendor-agnostic OAuth 2.0 & webhook pipelines across Pipedrive, Salesforce, HubSpot, GoHighLevel, Zoho, Google Calendar, Outlook Graph, Calendly, QuickBooks, Helcim, and Clover.
• Eliminated concurrent OAuth token refresh race conditions using PostgreSQL row-level locks (SELECT ... FOR UPDATE) paired with per-tenant async locks and Fernet encryption at rest.
• Hardened inbound webhooks with HMAC signature verification, an idempotent event deduplication table, and a daily subscription self-healing reconciler.
• Built deterministic cross-channel contact identity resolution (Voice, SMS/iMessage, Email, Social DMs) with human-takeover state machines and closed-loop AI learning from staff replies.