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date: 2026-06-22 tags: [decision-making, build-vs-buy, cost-of-ownership, min-maxing, harness] status: graduated graduated_to: CLAUDE.md # Key Conventions — minimise the cost of ownership

Minimise the cost of ownership — own only what pays for itself

Symptom — Across one session I repeatedly drifted to "let's build it ourselves" for a commodity layer (a visual-regression review surface), even after the maintainer made clear they didn't want to own it — needing correction each time. On the PR capturing this, the maintainer widened the framing: it isn't only "when I say I don't want to own X."

Root cause — I treated building / owning as the safe default. But ownership is a cost, not a default. Kudryashov's min-maxing software costs names four — creation, change, ownership, control — and over a project's life the cost of change dominates, tamed by "selectively taking ownership of only the necessary logic." Everything you own carries an ongoing change + control cost forever, so owning more than you must is a standing tax.

Fix — Behavioural. Treat ownership as a deliberate cost weighed per capability: does owning this buy enough control / differentiation to justify the lifetime cost of change it locks in? For Tempo's core (the thing that makes it Tempo) — yes, own it and invest control (tests, refactoring). For commodity / undifferentiated layers — minimise the cost of ownership: reach for managed / external tools, and when one fails a constraint, try another before retreating to building. A maintainer's "I don't want to own this" is one explicit trigger of the general rule, not the whole of it. And owning a thin, deterministic glue to escape a worse cost (vendor caps) is not an exception — it's the principle exactly: own only the necessary logic.

Guard — Graduated into CLAUDE.md Key Conventions ("Minimise the cost of ownership — own only what pays for itself"). Source: Konstantin Kudryashov, Min-Maxing Software Costs (Laracon EU 2015) — https://laravel-news.com/konstantin-kudryashov-min-maxing-software-costs.