Migrating a WordPress Site with AI: The Pattern That Worked

I moved a ten-year-old WordPress site to a new host last month. Three hundred posts, custom shortcodes, a broken taxonomy, and a child theme no one had touched since 2019. Done in two days, mostly hands-off. The pattern I used is repeatable, and it is the most agentic work I have shipped all quarter.

The Setup

I ran Claude Code locally against a fresh checkout of the old site's files. I gave it read access to the export XML and write access to a staging WordPress running in Docker. The job was simple to state: clean the content, migrate the taxonomy, rebuild the theme on a modern base.

The Three-Phase Flow

Phase one was pure analysis. Claude inventoried every post, classified content types, flagged broken shortcodes, and produced a CSV of issues. No writes, just reconnaissance. I reviewed the CSV over coffee and corrected three or four misclassifications by hand.

Phase two was the migration. Claude worked through the CSV, transforming shortcodes into Gutenberg blocks, consolidating the taxonomy, and writing each post to the staging site. After every batch of 20 posts it paused so I could spot-check the output. Anything I flagged got a correction that applied to all similar items.

Phase three was the theme rebuild. Claude converted the old child theme to a block theme, preserving the visual design but swapping the underlying mechanics. That part needed the most human review.

The Control Pattern

The key was the batch-and-review cadence:

for each batch of 20 posts:
    agent migrates batch
    agent writes migration log
    human reviews 3 random samples
    human approves or requests fixes
    fixes propagate to remaining batches

That cadence kept me in the loop without making me babysit every post. Error correction happened once per pattern, not once per instance. That is where the speed came from.

What Broke

Two things surprised me. First, agents are bad at spotting silent data loss. A shortcode converted to a block that renders nothing looks fine until a user notices a missing section. I added a render test to catch that.

Second, the theme rebuild needed more human input than I expected. Visual design is still hard to verify from code alone. I ended up doing side-by-side screenshots for every template.

The WordPress block editor handbook is worth reading before starting.