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Notes from the workshop. How Tessel gets built.

Engineering write-ups, customer stories and field guides. Written by the people who ship the runtime, answer the pages and sit in on month-end close.

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Isometric row of blocks growing taller along a trace line, the last one blue

Engineering

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How we trace two billion runs a month

Inside the pipeline that stores inputs, outputs and timings for every block, and opens a 30-day trace in under 200 ms.

September 24, 2026

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6 posts · Newest first

Engineering

9 min read

How we trace two billion runs a month

Inside the pipeline that stores inputs, outputs and timings for every block, and opens a 30-day trace in under 200 ms.

September 24, 2026

A tall stack of six ledger plates next to a short stack of two with a blue top

Customers

6 min read

Month-end close in two days at Halden

Halden replaced 31 cron jobs with one workspace. Ingrid Valk explains how finance ops cut close from six days to two.

September 18, 2026

A blue cube inside a fenced plate with a small stack of coins

Product

7 min read

Agents need budgets, not just prompts

A prompt says what an agent should do. A spend cap, a tool list and a named approver say what it may never do.

September 9, 2026

Isometric staircase of five steps with a blue cube on the top step

Operations

8 min read

A field guide to approval steps

Where to put a person in the loop, who should be the backup, and how long a run should wait before it escalates.

August 28, 2026

Seven day blocks in a row beside their ghost copies, the last one blue

Engineering

5 min read

Replaying last week before you ship

How replay runs a draft workflow against seven days of real events and shows the diff before anything reaches production.

August 14, 2026

A three by three grid of blocks on a plate with a tall blue block in the centre

Engineering

6 min read

Why every block compiles to TypeScript

Readable code you can review, test and take with you. Why we chose TypeScript as the output of every logic block.

July 30, 2026

Notes from the workshop. How Tessel gets built.

How we trace two billion runs a month

Every post. Filter by topic.

How we trace two billion runs a month

Month-end close in two days at Halden

Agents need budgets, not just prompts

A field guide to approval steps

Replaying last week before you ship

Why every block compiles to TypeScript

New posts, monthly. Plain text, no tracking.