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Mohit Sharma

SYS / 001

Mohit Sharma

I build. I ship. I write it down.

Engineering lead across backend systems, infrastructure and AI products. The building is the job. The writing is how I keep what it taught me.

Distributed systemsAI infrastructureBackendProduct engineering

Engineering notesSelected work

SYS / 002

I am an engineering lead working across backend systems, infrastructure and AI products. I tend to end up on the parts that have to keep working: the services everything else depends on, and the behaviour that only shows up under real load.

This site is the writing half of that. When something costs real effort to understand, I write down what actually happened, which assumption turned out to be load-bearing, and the explanation that makes it obvious in hindsight. Not tutorials, and not summaries.

SYS / 003

Currently exploring

  1. 01

    Agent engineering

    Tool design, control loops, and the failure modes that only appear once an agent runs unattended.

  2. 02

    LLM infrastructure

    Serving, batching and cost behaviour under real traffic rather than benchmark traffic.

  3. 03

    Retrieval and reranking

    Where recall actually leaks, and what a reranker buys that a better embedding does not.

  4. 04

    Evaluation

    Harnesses that fail honestly, and metrics that survive contact with a product decision.

  5. 05

    Distributed systems

    Consistency, backpressure and the long tail. Mostly the long tail.

SYS / 004

Selected work

All work

  • Cortex

    A multi-tenant retrieval platform: ingestion, chunking policy, hybrid search and a reranking stage that has to justify its own latency budget.

  • 2026-present

    HangarMart

    An aviation fleet platform: airworthiness gates, maintenance records and the scheduling constraints that come with keeping aircraft legally able to fly.

    Sole engineerTypeScriptFastifyDrizzle / PostgreSQLNext.jsReact NativeNo write-up yet

  • AI infrastructure

    Serving, retrieval, reranking and evaluation tooling for LLM-backed products, with the cost and latency behaviour that only shows up under real traffic.

    No write-up yet

  • Trading systems

    Backtesting, market data ingestion and the quantitative engineering around them, where correctness is measured against a replayable past.

    No write-up yet

  • PyaarSay

    A therapy marketplace: matching, scheduling and the product engineering around a service where the failure modes are human rather than technical.

    No write-up yet

SYS / 005

Engineering notes

All notes

Things I had to understand properly before I could explain them.

  • 2026.08.29

    The interface lied, so the catch never fired

    One missing file took the whole API down, past five correctly written try/catch blocks, because the driver could not fail where they were looking.

    4 minBackendFailure modes

  • 2026.08.28

    An idempotency key should remember successes, not failures

    Caching a 409 against an idempotency key turned a temporary refusal into a permanent one, and made the retry button a lie.

    4 minDistributed systemsAPI

  • 2026.07.25

    A check that cannot run has not passed

    A safety gate that silently narrows when its configuration is missing is worse than one that is absent, because it still reports a verdict.

    5 minSystem designSafety critical

  • 2026.07.25

    Seven predicates for one question

    Four screens showed an aircraft's status and three of them were wrong. The fix was not to pick the best of the seven definitions.

    5 minSystem designBackend

SYS / 006

How I work

  1. Question

    A system does something the current model does not predict.

  2. Investigate

    Read the source, the logs and the metrics. Distrust the summary.

  3. Experiment

    The smallest reproduction that isolates exactly one variable.

  4. Build

    Put it somewhere real, where the constraints are not hypothetical.

  5. Break

    Push it until it fails on purpose, while I am still watching.

  6. Understand

    The model that makes the failure look obvious in hindsight.

  7. Document

    Write it down while the confusing part is still fresh.

Writing the last one down is usually what produces the next question.

SYS / 008

Elsewhere

If any of this overlaps with what you are working on, I would like to hear about it.