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Jonathan Hazeley

Projects

Each of these is a case study in what was at risk, and what changed once it was fixed.

Entertainment, client name withheld2026

Proving a Migration, Not Just Doing One

Ten source tables moving platforms. No way to prove any of them arrived intact.

rows migrated on the pilot
678M

rows migrated on the pilot

automated checks per run
114

automated checks per run

average difference against source (2% tolerance)
0.01%

average difference against source (2% tolerance)

model-tiered subagents behind one human approval gate
22

model-tiered subagents behind one human approval gate

  • Databricks
  • Lakeflow Declarative Pipelines
  • Lakehouse Federation
  • Snowflake
  • Delta Lake (MERGE, Liquid Clustering)
  • Medallion architecture
Read case study
Lovelytics2025–2026

The Databricks Catalog Other Engineers Build Inside

Every engagement re-derived the same decisions. The knowledge lived in whoever was staffed.

reusable skills, client-generic by construction
118

reusable skills, client-generic by construction

categories, from platform core to AI and agents
13

categories, from platform core to AI and agents

  • Databricks
  • Python
  • FastMCP
  • Model Context Protocol
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Personal project2025–2026

Proving Agent Skills Actually Work

A skill that passed once and a skill that works look identical from outside.

meta-skills for authoring and evaluation
~24

meta-skills for authoring and evaluation

graduation bar over k independent runs
pass^k ≥ 0.95

graduation bar over k independent runs

  • Python
  • Model Context Protocol
  • OAuth 2.1
  • uv workspace
Read case study
Personal project2025–2026

Architecture Enforced by Gates, Not Convention

Architecture documents describe intent. Codebases drift from it within months.

packages split on a network-and-secrets axis
7

packages split on a network-and-secrets axis

AST gates failing CI on a boundary violation
4

AST gates failing CI on a boundary violation

  • Python
  • PostgreSQL
  • Databricks
  • AST analysis
Read case study
Public sector, client name withheld2025

Statewide Transportation Data, Made Trustworthy

A feed lapsed. The dashboard still rendered, with a gap nobody could see.

improvement in statewide reporting availability
30%

improvement in statewide reporting availability

faster onboarding for a new data source
60%

faster onboarding for a new data source

  • Databricks
  • Delta Live Tables
  • PySpark
  • Azure OpenAI
Read case study
Snap One (acquired by ADI Global)2021–2025

The Metrics Behind a 50% EBITA Increase

Everyone had the data. Nobody had a reason to believe it.

EBITA increase (~$50M) the pipelines contributed to
50%

EBITA increase (~$50M) the pipelines contributed to

Databricks pipelines integrating IoT and SaaS sources
15+

Databricks pipelines integrating IoT and SaaS sources

  • Databricks
  • SQL
  • Python
  • Power BI
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Real Estate, client name withheld2026

Costing a Migration Nobody Could Log Into

The scope doubled to a 2,000-task orchestration monolith. Access to the warehouse beneath it never arrived.

orchestration tasks in the monolith being replaced
2,000

orchestration tasks in the monolith being replaced

hours estimated for the transformation component
~6,800

hours estimated for the transformation component

  • Azure Databricks
  • Databricks Workflows
  • Databricks Model Serving
  • BigQuery
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Healthcare, client name withheld2025–2026

Hospital Billing, Modeled Once

The reports disagreed. The worse case was the one where they agreed and were still wrong.

Epic Clarity cube views migrated (19 dimension, 7 fact)
26

Epic Clarity cube views migrated (19 dimension, 7 fact)

source keys reconciled, none unaccounted for
7.4M

source keys reconciled, none unaccounted for

  • Databricks
  • Unity Catalog
  • dbt
  • Fivetran
Read case study