add: readmes and boilerplate

AGENT.md

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+# Development guide
+
+## Backend/Golang
+
+Do not alter go.mod directly, instead, use the CLI tools `go mod tidy`, `go mod
+init`, and so forth.
+
+Write tests for all public APIs. Never test a private API; if it feels like we
+need to do that, refactor the code to make the difficult-to-test part a new
+package.
+
+Prefer to write clear function and variables names over comments. In general,
+avoid writing comments when the same logic can be communicated with code.
+
+Follow https://github.com/golang-standards/project-layout/blob/master/README.md
+for layout
+
+The main function should be very small.
+
+Prefer to test with real implementations rather than mocks. For example, bring
+up a real HTTP server to test.
+
+Generally conform to resource-oriented design describe in
+https://google.aip.dev/general.
+
+## Frontend/Typescript
+
+Do not alter package.json directly, instead, use the CLI tool `npm`.
+
+Write unit tests for all exported APIs. Never test private APIs. If it feels
+like we need to test private methods, refactor the code to make the
+difficult-to-test part of a new package.
+
+Prefer to keep the front-end code minimal. If there is a need to transform data,
+do that on the backend, and add a new API to load the transformed data.