# diljitpr.net — Diljit's Personal Site

> Diljit is an Engineering Manager at Avoca (YC '23), where he leads the Deployed Engineering team building AI voice agents for home-services companies, and the founder of QRCodeStack (https://qrcodestack.com), the world's most affordable dynamic QR code generator. Previously a senior engineer at Wayfair, SingleStore, Twilio, Zalando, PayPal, Nutanix, and Hewlett Packard. He specialises in distributed systems, system design, PostgreSQL, Kafka, and AI voice agents. This site contains technical blog posts, an interactive LLM course, and a professional biography.

## Services

- AI Voice Agent Development Services — freelance & fractional: https://diljitpr.net/services.html — voice AI agent builds (telephony, ASR, LLM orchestration, TTS, tool calls), eval harnesses and observability, voice agent audit & rescue, agent architecture and platform selection (Vapi, Retell, LiveKit, Pipecat), fractional AI engineering leadership, and the PostgreSQL/Kafka backend layer behind the agent. Verticals: home services, healthcare, customer support, restaurants, financial services, outbound reminders. Contact diljit@diljitpr.net.

## Blog Posts

- OpenAI Realtime on a Phone Line: Telnyx SIP + Cekura Tests (2026-09-15): https://diljitpr.net/blog-post-2026-09-15-openai-realtime-telnyx-sip-cekura-testing.html — connecting a Telnyx number to OpenAI's gpt-realtime speech-to-speech model over SIP: project webhook and accept call, Standard Webhooks verification, the TeXML Dial settings that matter (outbound voice profile, G.711, ;secure=srtp), the session audio format, greeting and turn-detection traps, prompt rules for speech-to-speech, and a Cekura simulated-caller test loop with interruption and thinking-pause scenarios
- Learning Photography With Codex and a Sony ZV-E10 II (2026-09-10): https://diljitpr.net/blog-post-2026-09-10-learning-photography-with-codex-sony-zv-e10-ii.html — all 10 photos from a beginner photography lesson with Codex and Sony Imaging Edge Desktop, with EXIF settings and a chronological account of focus, framing, background changes, aperture, zoom, shutter speed and ISO
- Best Clipboard Manager for Mac in 2026: 4 Worth Installing (2026-09-04): https://diljitpr.net/blog-post-2026-09-04-best-clipboard-manager-mac.html — four Mac clipboard managers compared on history limits, search, privacy, sync and price: SnipVault (all-in-one with screenshot OCR and snippets, $79 lifetime, by the author), Paste (iPhone/iPad sync), Maccy (free, open source, 999-item cap) and Raycast (launcher with 3-month free history); covers macOS Tahoe's built-in Spotlight clipboard and an FAQ on passwords, sync and whether you need one
- A Weekend Getaway to VAMA Retreats, Nandi Hills — With Two Dogs, One Pool, and a Lot of Tennis Balls (2026-08-31): https://diljitpr.net/blog-post-2026-08-31-vama-retreats-nandi-hills-pet-friendly-weekend.html — first-hand trip report from a pet-friendly resort near Bangalore at the foot of Nandi Hills: the 50-60 km drive and why to leave before 7am, what distinguishes a pet-friendly property (dedicated pet pool, enclosed leash-free lawns, pet-friendly garden villas, pet meals) from a pet-tolerant one, the shallow dog plunge pool and its inconsistent cleaning, open-lawn exercise for under-exercised large breeds, camp night with a bonfire and BBQ, a ten-item packing list for travelling with dogs in India, and an FAQ on distance, pet policy and trip length
- Your QR Code Is a Redirect — It Should Be an Engagement Layer (2026-08-27): https://diljitpr.net/blog-post-2026-08-27-qr-code-engagement-offline-retargeting.html — QR codes as a customer engagement layer rather than a redirect: post-purchase scan-rate benchmarks (packaging 8-15% of units, inserts 5-12%, labelled codes 3-4x unlabelled), a four-branch intent router (love it / something's wrong / want more / feedback) that captures declared intent, a channel.geo.asset.variant code-ID taxonomy for per-SKU and per-batch attribution, pixel-based offline retargeting and suppression audiences from physical touchpoints, a scan-to-revenue measurement funnel with cost per retargetable customer, and GDPR/CPRA consent limits
- The Essential Metrics for Voice AI Agents — From Milliseconds to Dollars (2026-08-25): https://diljitpr.net/blog-post-2026-08-25-essential-metrics-voice-ai-agents.html — five-layer voice agent scorecard: turn latency and endpointing, weighted WER and intent coverage, verified task success, sentiment slope and repeat contact, compliance adherence, and the money layer (resolved containment, cost per resolved contact, revenue per answered call, ROI equation)
- I Lost $12,000 Dropshipping in India — And Why I Think It's a Capital-Intensive Business (2026-08-24): https://diljitpr.net/blog-post-2026-08-24-losing-12000-dollars-india-dropshipping.html — first-person post-mortem on Indian COD dropshipping: ad dependency, creative treadmill, $350–475 influencer videos, 20–40% RTO cut to 8% via WhatsApp + call confirmation, Shopify/Delhivery/Blue Dart stack
- Bayesian and Sequential A/B Testing — When You Peek Weekly (2026-08-23): https://diljitpr.net/blog-post-2026-08-23-bayesian-sequential-ab-testing.html — worked personal-SaaS first-create confetti vs pricing-cards example with analytics counts
- Getting Your Ideal Customer Profile (ICP) Right (2026-08-23): https://diljitpr.net/blog-post-2026-08-23-getting-icp-right.html
- Running a Radical Candor Book Club With Your Engineering Team (2026-08-06): https://diljitpr.net/blog-post-2026-08-06-radical-candor-book-club-engineering-team.html
- What Is an AI Agent Harness? A Plain-English Guide, Plus One in 80 Lines of Python (2026-08-03): https://diljitpr.net/blog-post-2026-08-03-what-is-an-ai-agent-harness.html
- Agent Loops, Swarms, and Graphs: A 20-Minute Experiment on Your Laptop (2026-08-01): https://diljitpr.net/blog-post-2026-08-01-agent-loops-swarms-graphs-laptop-experiment.html
- A Dummy's Guide to Evals for AI Agents (2026-07-26): https://diljitpr.net/blog-post-2026-07-26-dummys-guide-to-evals-ai-agents.html
- What Are Evals? A Plain-English Guide, Illustrated by a Real Voice AI Agent (2026-07-26): https://diljitpr.net/blog-post-2026-07-26-what-are-evals-voice-agent-example.html
- Evals, Testing, and Observability for Voice AI Agents: A Field Guide (2026-07-26): https://diljitpr.net/blog-post-2026-07-26-evals-testing-observability-voice-ai-agents.html
- The Anatomy of a Great Prompt (2026-02-11): https://diljitpr.net/blog-post-2026-02-11-anatomy-of-great-prompt-llm-guide.html
- Inside ~/.claude: Claude Code Filesystem Architecture (2026-02-24): https://diljitpr.net/blog-post-2026-02-24-inside-dot-claude-filesystem-architecture.html
- Using PostgreSQL as a Dead Letter Queue (2025-12-25): https://diljitpr.net/blog-post-postgresql-dlq.html
- How We Migrated a Postgres Database on GCP with Minimal Downtime (2024-08-08): https://diljitpr.net/blog-post-2024-08-08-postgres-database-migration-gcp-minimal-downtime.html
- Using Merkle Trees to Detect Data Variance (2024-09-02): https://diljitpr.net/blog-post-2024-09-02-merkle-trees-detect-data-variance.html
- Sending Automated Appointment Reminders with PostgreSQL, n8n, and WhatsApp (2026-02-01): https://diljitpr.net/blog-post-2024-08-10-sending-automated-appointment-reminders-postgresql-google-sheets-n8n-whatsapp.html
- How Airline Reservation Systems Work Under the Hood (2024-08-08): https://diljitpr.net/blog-post-2024-08-08-how-airline-reservation-systems-work.html
- Building a Real-Time, Streamable Online FM Radio Player (2024-08-08): https://diljitpr.net/blog-post-2024-08-08-building-real-time-streamable-online-fm-radio-player.html
- Running a 3-Node Home Lab Cluster on Refurbished Lenovo ThinkCentres (2024-08-09): https://diljitpr.net/blog-post-2024-08-09-running-3-node-home-lab-cluster-refurbished-lenovo-thinkcentres.html

## Course

- How Large Language Models Work — Interactive $1 Course: https://diljitpr.net/course-how-llms-work.html

## Other

- Blog index: https://diljitpr.net/blog.html
- Photo gallery: https://diljitpr.net/photos.html
- Photo album — Evening in Bangalore (2026-09-13): https://diljitpr.net/album-bangalore-sunset.html — seven frames of one September evening shot from a Bangalore balcony, from blue hour through a pink cloudburst to the last embers over the skyline

## Author

Diljit — Engineering Manager, Deployed Engineering @ Avoca (YC '23); Founder of QRCodeStack
Email: diljit@diljitpr.net
LinkedIn: https://www.linkedin.com/in/diljitpr/
Previously: Wayfair (Senior SDE, Supply Chain), SingleStore, Twilio, Zalando, PayPal, Nutanix, HP