feat: ship a useful default Python init template

The empty class generated by `dagger module init python` makes every user
recreate the same Workspace-to-Directory-to-Container plumbing before the
module can do useful work. TypeScript SDK #10 established a small working
module as the cross-SDK default while retaining a blank starter explicitly.

Add the Python equivalent: capture the filtered workspace source, accept a
pinned base image through the constructor, and return a container with that
source mounted. Keep the target project generic; uv remains an implementation
choice in the module's generated pyproject rather than an assumption about the
workspace being automated.

Use Python's alternate `create` constructor to translate the user-facing
Workspace input into the object's durable `source` and `base_image_address`
fields. Module objects are reconstructed from those fields before later
function calls, so the dataclass-generated `__init__` must remain available
for state hydration.

Rename the previous minimal template to `empty`, leave `legacy` unchanged, and
make `default` explicit in the init signature. The constructor argument is
named `ws` so it does not collide with the CLI's top-level `--workspace` flag.

Signed-off-by: Guillaume de Rouville <guillaume@dagger.io>

Author: grouville

python-sdk.dang

@@ -136,14 +136,15 @@ type PythonSdk {
   new module's `path`. Engine-owned files (dagger-module.toml, workspace config
   updates) are produced by the engine and merged with this changeset.
 
-  Pass `template` to materialize files from templates/<template>. The empty
-  default uses this module's minimal template.
+  Pass `template` to pick a starter under templates/<template>. It defaults to
+  `default` (a small working module). Use `empty` for a bare object class. An
+  explicitly empty template also selects `default` for compatibility.
 
   Pass `pythonVersion`, `useUv`, or `baseImage` to customize the generated
   pyproject.toml. Defaults leave the template untouched: the template's Python
   version is used, uv is enabled, and no base image override is written.
   """
-  pub initModule(ws: Workspace!, name: String!, path: String!, template: String! = "", pythonVersion: String! = "", useUv: Boolean! = true, baseImage: String! = ""): Changeset! {
+  pub initModule(ws: Workspace!, name: String!, path: String!, template: String! = "default", pythonVersion: String! = "", useUv: Boolean! = true, baseImage: String! = ""): Changeset! {
     let rawPath = path.trimPrefix("./").trimPrefix("/")
 
     let modPath = if (rawPath == "" or rawPath == ".") {
@@ -154,7 +155,7 @@ type PythonSdk {
       rawPath.trimSuffix("/")
     }
 
-    let selectedTemplate = if (template == "") { "minimal" } else { template }
+    let selectedTemplate = if (template == "") { "default" } else { template }
 
     if (currentModule.source.exists("templates/" + selectedTemplate) == false) {
       raise "unknown init template: " + template

templates/minimal/pyproject.toml.tmpl templates/default/pyproject.toml.tmpltemplates/minimal/pyproject.toml.tmpl renamed to templates/default/pyproject.toml.tmpl

@@ -0,0 +1,39 @@
+import dagger
+from dagger import dag, function, object_type
+
+
+@object_type
+class {{ .ModuleType }}:
+    source: dagger.Directory
+    base_image_address: str
+
+    @classmethod
+    def create(
+        cls,
+        ws: dagger.Workspace,
+        base_image_address: str = "alpine:3.21",
+    ):
+        return cls(
+            source=ws.directory(
+                "/",
+                exclude=[
+                    "**/.dagger",
+                    "**/.git",
+                    "**/.venv",
+                    "**/__pycache__",
+                    "**/node_modules",
+                    "**/dist",
+                ],
+            ),
+            base_image_address=base_image_address,
+        )
+
+    @function
+    def container(self) -> dagger.Container:
+        """A container with the workspace source, ready to build."""
+        return (
+            dag.container()
+            .from_(self.base_image_address)
+            .with_directory("/src", self.source)
+            .with_workdir("/src")
+        )

templates/default/src/{{.ModulePackage}}/__init__.py.tmpl

@@ -0,0 +1,12 @@
+[project]
+name = "{{ .ModuleName }}"
+version = "0.1.0"
+requires-python = ">=3.14"
+dependencies = ["dagger-io"]
+
+[build-system]
+requires = ["uv_build>=0.8.4,<0.9.0"]
+build-backend = "uv_build"
+
+[tool.uv.sources]
+dagger-io = { path = "sdk", editable = true }

templates/empty/pyproject.toml.tmpl

@@ -1,5 +1,6 @@
 from dagger import object_type
 
+
 @object_type
 class {{ .ModuleType }}:
     pass