Where the readings come from, what carries them, and who is responsible.

Three sources, each with one job.

Open data and global providers. City open-data portals (CKAN and the like), Smart Citizen, OpenAQ, Sensor.Community, Metroverse, fablabs.io, Earth observation, planetary boundary science. An adapter pulls on a schedule. These fill the cells that are already counted somewhere.

Ground observation. Sensor kits, drones, water and soil tests, field surveys, WhatsApp reporting, the tools a lab or a community already owns. These fill the cells nobody else counts. A campaign like Making Sense Bali is how a community creates these readings on its own terms. Every ground reading passes a calibration and consent step before it counts.

People. Where neither exists, a partner lab or a city's data lead enters a reading by hand through the workbench, with a source cited. The workbench is also where submissions are reviewed and where a member decides what may be published.

Every reading, whichever route it took, lands in the same cell file, marked live, partial or mock so a reader always knows how far to trust it.

PLANETAI is the network that carries and reads the readings. It has three levels, and the Index is built from the bottom up.

Hyperlocal nodes. A small computer in the place itself. It reads air, heat, land and whatever sensors are attached, keeps the full record locally, and hands upward only what the next level needs. It also does the first reading of the data: when something changes in its square kilometre it says so to the people nearby and records whether they responded. Two run today; Bali is the first pledged place with one.

City, regional and bioregional nodes. The same machine, one level up. It receives summaries from the nodes below it, aggregates them, and reads them against its own scale: a city node sees the district pattern a single node cannot, a bioregional node sees the watershed. Each level adds the intelligence appropriate to its scale and hands its own summary up. These levels are the next PLANETAI releases; today, hyperlocal nodes report to the Index directly.

The Index. The top of the chain and the thinnest layer. It holds the cell file for every place, computes the score, and publishes the profiles. It does not hold raw readings; those stay where they were made.

The point of the chain is not only measurement. Each level can act at its own speed. A node warns a household in minutes. A city node can put a district pattern in front of a council in a week. The Index shows, a quarter later, whether the place moved. Faster action closer to the ground is the design, and ρ is how it is scored.

Every place that has pledged gets a profile: its cells, its sources, its readings with their trust marks, its score when it has one, and its node if it runs one. The profile is the place's own. In later releases a member will be able to embed it on its own website, take the data out in open formats, and host its own instance of the Index on its city or regional node so the profile is served from the place it describes.

Then the loop closes. A reading appears. Someone acts, or does not. The node counts which. The next reading shows whether the place changed.

The Index is built collectively, and the responsibility sits with the members. Fab City runs the method, the shared cell file and this site. A member city, region, island or country is responsible for its own profile: connecting the sources that exist, running the campaigns for what does not, naming a steward who reviews what is published, and running or hosting a node where it can. A profile with empty cells is not a failing grade. It is a to-do list, and it is public so that the member, and everyone else, can see what is left.

Members are responsible for their own profile; Fab City is responsible for the method. An empty cell is a to-do, not a grade.

Open your place's profile → Add a source → Run a campaign → Run a node →