Rename build namespace to plain.assets.build

`plain build` moved to `plain assets build` in the last commit, but the two
contracts it reads still used the historical `plain.build` namespace:
- `[tool.plain.build.run]` for user-defined build shell commands
- `[project.entry-points."plain.build"]` for package build hooks

Both move to `plain.assets.build` so the namespace follows the orchestrator
that owns it. plain-tailwind and plain-esbuild update their entry-point group;
plain-api and plain-tailwind READMEs update the TOML example.

Author: davegaeddert

plain-api/plain/api/README.md

@@ -449,10 +449,10 @@ uv add --dev openapi-spec-validator
 
 ### Deploying
 
-To build the JSON when you deploy, add a `build.run` command to your `pyproject.toml` file:
+To build the JSON when you deploy, add a build command to your `pyproject.toml` file:
 
 ```toml
-[tool.plain.build.run]
+[tool.plain.assets.build.run]
 openapi = {cmd = "plain api generate-openapi --validate > app/assets/openapi.json"}
 ```
 

plain-assets/plain/assets/README.md

@@ -51,6 +51,21 @@ By default, this [generates "fingerprinted" and compressed versions of the asset
 
 The purpose of fingerprinting the assets is to allow the browser to cache them indefinitely. When the content of the file changes, the fingerprint will change, and the browser will use the newer file. This cuts down on the number of requests that your app has to handle related to assets.
 
+### Pre-compile build steps
+
+`plain assets build` runs three things in order before compiling assets:
+
+1. User-defined shell commands from `[tool.plain.assets.build.run]` in your `pyproject.toml`. Useful for codegen that produces files into `app/assets/`:
+
+    ```toml
+    [tool.plain.assets.build.run]
+    openapi = {cmd = "plain api generate-openapi --validate > app/assets/openapi.json"}
+    ```
+
+2. Package-registered build hooks via the `plain.assets.build` entry-point group. Packages like `plain.tailwind` and `plain.esbuild` ship one of these to compile CSS / JS before the asset fingerprinter runs.
+
+3. The asset compile itself (fingerprinting, compression).
+
 ## Using `AssetView` directly
 
 In some situations you may want to use the `AssetView` at a custom URL, for example to serve a `favicon.ico`. You can do this quickly by using the `AssetView.as_view()` class method.

plain-assets/plain/assets/cli.py

@@ -59,6 +59,7 @@ def build(keep_original: bool, fingerprint: bool, compress: bool) -> None:
         for name, data in (
             pyproject.get("tool", {})
             .get("plain", {})
+            .get("assets", {})
             .get("build", {})
             .get("run", {})
             .items()
@@ -70,7 +71,7 @@ def build(keep_original: bool, fingerprint: bool, compress: bool) -> None:
                 sys.exit(result.returncode)
 
     # Then run installed package build steps (like tailwind, esbuild)
-    for entry_point in entry_points(group="plain.build"):
+    for entry_point in entry_points(group="plain.assets.build"):
         print_event(f"{entry_point.name}...")
         entry_point.load()()
 

plain-esbuild/pyproject.toml

@@ -11,7 +11,7 @@ dependencies = ["plain<1.0.0", "plain.assets>=0.1.0,<1.0.0"]
 [project.entry-points."plain.dev"]
 "esbuild" = "plain.esbuild.entrypoints:run_dev_build"
 
-[project.entry-points."plain.build"]
+[project.entry-points."plain.assets.build"]
 "esbuild" = "plain.esbuild.entrypoints:run_build"
 
 [tool.hatch.build.targets.wheel]

plain-tailwind/plain/tailwind/README.md

@@ -195,7 +195,7 @@ The build command automatically installs the Tailwind CLI if it is not present,
 You can automate this by adding a build command to your `pyproject.toml`:
 
 ```toml
-[tool.plain.build.run]
+[tool.plain.assets.build.run]
 tailwind = {cmd = "plain tailwind build --minify"}
 ```
 

plain-tailwind/pyproject.toml

@@ -16,7 +16,7 @@ plain-tailwind = "plain.tailwind.cli:cli"
 [project.entry-points."plain.dev"]
 "tailwind" = "plain.tailwind.entrypoints:run_dev_build"
 
-[project.entry-points."plain.build"]
+[project.entry-points."plain.assets.build"]
 "tailwind" = "plain.tailwind.entrypoints:run_build"
 
 [tool.hatch.build.targets.wheel]