Articles

Measured findings on context engineering, loop engineering, and the instruction files that steer AI coding agents: CLAUDE.md, AGENTS.md, system prompts, and the checks around them.

A developer at a desk faced with an eleven-file diff behind a single green check, deciding whether to read four hundred lines to approve a one-line ask; three stacked layers guard the path from the agent's output to the main branch: a steering rule, a review pass that runs the code, and a deterministic gate that refuses a write outside the task's named files.

Field Notes

Opus 5: How to Review Generated Code

Opus 5 made writing nearly free and moved the cost onto review; a diff now lands eleven files deep behind a green check nobody read. The answer is not a smarter reviewer but defense in depth: steer the model, run a real review, and gate the rest.

Gábor Mészáros · August 27, 2026 · 10 min read

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A developer hits Approve on a four-hundred-line AI diff behind a green check while four more agent pull requests stack up in the queue behind it; off to the side a second robot leans in to grade the first robot's diff, its verdict fraying line by line, while a plain gate stamps the same refusal on file 1 and file 100.

Field Notes

Opus 5: Review bottleneck

Coding agents made code a commodity; the scarce work now is reading it. The obvious fix, a second model checking the first, quietly rebuilds the problem one guess at a time. What actually scales is a gate that does not read the diff at all.

Gábor Mészáros · August 19, 2026 · 6 min read

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A dark terminal shows Opus 5 answering a one-line request with a long, rambling reply; an arrow points to a green Stop-hook card whose word-count meter runs green to a 180-word budget then overflows amber to 217 words, marked 'answer first, then stop'.

Field Notes

Opus 5: How to Fix Verbose Output

Opus 5 runs verbose, and a plain `Be concise` rule does not hold it. Three levers get concise replies back, weakest to strongest: a reply-shape rule, an output style, and a Stop hook that refuses a long reply. A plugin carries the setup across projects.

Gábor Mészáros · August 14, 2026 · 7 min read

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A CLAUDE.md open to two rules under two different headings, one near the top reading scratchpad ships without tests and one far below reading write a test for every function, a line drawn between them showing they collide, and the lower rule marked as the one the model keeps.

Field Notes

Opus 5: Cost of Instruction Conflicts

Two rules in your instruction file disagree. The model picks one, follows it to the letter, and moves on without a word. The other goes dead, and where each rule sits in the file decides which one you lost.

Gábor Mészáros · August 5, 2026 · 8 min read

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A 300-line CLAUDE.md with most of its lines greyed out under a DELETE stamp, and a small handful of lines left highlighted, each tagged with a property you can check without running the model: names a construct, does not conflict, loads where it applies.

Field Notes

Opus 5: Delete your CLAUDE.md?

Boris Cherny is right that most of your instruction file is dead weight. But deleting it treats a quality problem as a quantity problem, and cannot tell you which rules were load-bearing.

Gábor Mészáros · August 4, 2026 · 9 min read

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