PostHog says agents now open 70% of the pull requests in its monorepo

At PostHog, most pull requests in the monorepo now arrive with an agent's name on them. A person still has to read them. The company's own list of what its engineers spend time on includes "babysitting outstanding PRs", filed next to monitoring running agents and fixing their errors ^[5].

The move from around 20% to 70% is a rise of 50 percentage points across four months ^[1][2], averaging about 12.5 points a month ^[3], which multiplies the agent share by 3.5 ^[4]. A team copying the approach should expect its review queue to grow inside a quarter.

The figure counts who opened the pull request. The newsletter does not say how many agent-opened PRs merged, how many a person rewrote first, or how long any of them waited for review ^[14].

PostHog describes its engineers building the instrumentation to keep up: standup bots, repo summary scouts, custom setups for monitoring in-progress PRs, feedback surveys, changelog automations and anomaly alerts ^[6]. The company also says AI raised what managers and customers expect on productivity and polish ^[13], and warns that without a clear direction you can feel productive without making progress, because AI lets you add anything you think of ^[15].

Direction-setting is the other half of PostHog's answer. Its requests-for-comments repos hold nearly 1,000 direction-setting decisions, on topics including dashboard MCP improvements, environments and picking programming languages ^[7]. One RFC proposes a unified health page; Rafa wrote it and the decision was ultimately his ^[8]. "We have 4 of them right now, but 3 of them were created in the last couple months, so they might start proliferating," he wrote ^[9]. The design runs checks through Dagster and stores them in Postgres ^[10].

This is PostHog writing about PostHog in its own newsletter, and the author identifies himself as a marketer ^[12]. The 70% is a self-reported count from one repository.

It is a useful number for a team that already has agents opening PRs and wants to know what its engineers do next. For your own version, tag one week of merged PRs on two axes: opened by an agent or by a person, and merged as written or substantially rewritten first. The agent-opened, rewritten cell is your supervision cost, and the median hours a PR waits for first review tells you whether that cost is already binding. I would treat a rising agent share as a forecast of review capacity and not as an input to headcount, and the cost of that choice is that you will under-credit the PRs an agent got right that nobody had to touch.