Building 8 Tableau Viz Extensions to Rebuild a Tableau Public Classic

Eric explains what went wrong that morning. Claude built dashboard extensions when he wanted viz extensions, and in places just built straight web elements. Both kinds of extension are web pages underneath, but the missing piece was the Tableau side: the .trex file that Desktop actually loads.

That is why this run leans on more careful prompts, and why he points out that the new build includes a set of checks that were missing the first time.

While the scaffold runs, Eric walks through hosting options: pull from the Tableau Exchange, a locked down S3 bucket that only lets Tableau Cloud and your machine in, Cloudflare file hosting with Tableau Cloud IPs allowlisted, GitHub Pages (added later at 32:04), and TableauOps at ext.tableauops.com, where you sign in with an emailed code, drop a folder or zip, and download a .trex pointed at that host.

For this build he skips the public hosting prompt and runs everything from the localhost kit server.

Prompt A starts the kit server, builds the parent and child directory structure, and sets up how each child extension and its .trex relate to the parent server. It clones a viz starter that every extension uses as its template, plus a shared contract so the agents work in coordination.

Prompt B, the orchestration fan out, has one paragraph per extension and tells Claude to spin up a sub-agent for each. Eric also asked for a monitor page in the browser so he could watch each extension build, instead of waiting 30 minutes and getting the wrong thing like the morning run.

To load one, open the Marks card drop down, choose Add Extension, then Access Local Viz Extensions and pick the .trex. Eric checks the extension URL in the dialog first, since that is where the web files are served from.

Each extension opens on a splash screen that lists its encodings and which are required or optional: category plus a measure, or item, date and value. Drop the fields in and it renders.

The compare bars come in first, computing change percent from the date field, and the region sparklines follow once the date is set to month. The trellis and dot timeline land the same way, with the dot timeline showing a total bar alongside each row.

Several of them want more space than their zone gives them, so pieces get cut off. Eric also has to swap the data source mid build because his download of Pradeep's data had no region field, which later shifts the dates.

With state and sales on the map and city added as detail, hovering shows a top five city breakdown for the state, like the original. Eric notes that viz extensions do not talk to each other directly unless something like a dashboard extension coordinates them.

Then he tries Use as Filter on the dashboard and it works. Clicking the Consumer segment filters the rest of the board.

Adding the sales banner, Eric points out that a change to the manifest or .trex file is not picked up until you go back through Add Extension and select it again. That matters when you move from localhost to public hosting.

For code changes there are two ways to reload: the reload button on the extension, or the drop down where you select the same extension again.

The category sales extension still was not showing percent change. Its base year was 2021, but the updated Superstore set only had 2023 through 2026. Setting the year to 2023 brought the values back.

For the extensions that kept asking for too much room, Eric's next prompt is to make them responsive, so each reads the size of its canvas and scales to it.