Preserve .designer.ipynb suffix when translating notebook task paths (#5370)

## Summary

Lakeflow Designer files keep their full `.designer.ipynb` suffix when
imported into the workspace, unlike regular notebooks (`.py`, `.ipynb`,
`.r`, `.scala`, `.sql`) which lose their extension on import.

`translateNotebookPath` in `bundle/config/mutator/translate_paths.go`
unconditionally stripped `path.Ext(localRelPath)`. For a
`foo.designer.ipynb` path, `path.Ext` returns `.ipynb`, leaving
`foo.designer` — the deployed job's `notebook_path` then points at a
file that does not exist.

## Fix

Add `notebook.ExtensionDesigner = ".designer.ipynb"` and a
`StripExtension` helper in `libs/notebook/ext.go` that special-cases the
designer suffix. Apply it in both branches of `translateNotebookPath`
(the `skipLocalFileValidation` branch and the post-detection branch).

## Reproduction

A bundle with:

```yaml
resources:
  jobs:
    designer_job:
      tasks:
        - task_key: t
          notebook_task:
            notebook_path: ./foo.designer.ipynb
```

| | Before | After |
|---|---|---|
| File in workspace | `foo.designer.ipynb` (`DESIGNER_FILE`) ✓ |
`foo.designer.ipynb` (`DESIGNER_FILE`) ✓ |
| Deployed `notebook_path` | `foo.designer` → 404 ✗ |
`foo.designer.ipynb` ✓ |

## Tests

- `libs/notebook/ext_test.go` — `TestStripExtension` covers `.py /
.ipynb / .r / .scala / .sql`, the `.designer.ipynb` keep-case, and
no-extension input.
- `bundle/config/mutator/translate_paths_test.go` —
`TestTranslatePathsDesignerNotebook` (file present, mixed designer +
regular tasks) and
`TestTranslatePathsDesignerNotebookSkipLocalFileValidation`
(config-remote-sync branch). Both assert designer suffix is preserved
and `.py` / `.ipynb` are still stripped.

## Out of scope

Other call sites strip `path.Ext` in the same pattern
(`libs/sync/snapshot_state.go`, `bundle/generate/downloader.go`,
`cmd/workspace/workspace/import_dir.go`,
`libs/filer/workspace_files_extensions_client.go`). The job-task path
covers the reported user-visible bug; whether designer files need the
same special-case in sync / generate / import-dir flows depends on
whether they round-trip through those paths in a way the workspace API
doesn't already handle. Happy to extend in a follow-up if reviewers
want.

Author: artchen-db

NEXT_CHANGELOG.md

@@ -9,5 +9,6 @@
 
 ### Bundles
 * Retry transient HTTP 504 Gateway Timeout errors in direct deployment engine ([#5349](https://github.com/databricks/cli/pull/5349)).
+* Preserve `.designer.ipynb` suffix when translating notebook task paths so Lakeflow Designer files referenced from a `notebook_task` resolve correctly in the workspace ([#5370](https://github.com/databricks/cli/pull/5370)).
 
 ### Dependency updates

acceptance/bundle/paths/designer_notebook/databricks.yml

@@ -0,0 +1,14 @@
+bundle:
+  name: designer_paths
+
+resources:
+  jobs:
+    designer_job:
+      name: designer_job
+      tasks:
+        - task_key: designer_task
+          notebook_task:
+            notebook_path: ./src/test.designer.ipynb
+        - task_key: regular_task
+          notebook_task:
+            notebook_path: ./src/regular.ipynb

acceptance/bundle/paths/designer_notebook/output.txt

@@ -0,0 +1,10 @@
+[
+  {
+    "task_key": "designer_task",
+    "notebook_path": "/Workspace/Users/[USERNAME]/.bundle/designer_paths/default/files/src/test.designer.ipynb"
+  },
+  {
+    "task_key": "regular_task",
+    "notebook_path": "/Workspace/Users/[USERNAME]/.bundle/designer_paths/default/files/src/regular"
+  }
+]

acceptance/bundle/paths/designer_notebook/script

@@ -0,0 +1 @@
+$CLI bundle validate -o json | jq '.resources.jobs.designer_job.tasks | map({task_key, notebook_path: .notebook_task.notebook_path})'

acceptance/bundle/paths/designer_notebook/src/regular.ipynb

@@ -0,0 +1,10 @@
+{
+  "cells": [],
+  "metadata": {
+    "application/vnd.databricks.v1+notebook": {
+      "language": "python"
+    }
+  },
+  "nbformat": 4,
+  "nbformat_minor": 0
+}

acceptance/bundle/paths/designer_notebook/src/test.designer.ipynb

@@ -0,0 +1,10 @@
+{
+  "cells": [],
+  "metadata": {
+    "application/vnd.databricks.v1+notebook": {
+      "language": "python"
+    }
+  },
+  "nbformat": 4,
+  "nbformat_minor": 0
+}

bundle/config/mutator/translate_paths.go

@@ -196,8 +196,7 @@ func (t *translateContext) rewritePath(
 
 func (t *translateContext) translateNotebookPath(ctx context.Context, literal, localFullPath, localRelPath string) (string, error) {
 	if t.skipLocalFileValidation {
-		localRelPathNoExt := strings.TrimSuffix(localRelPath, path.Ext(localRelPath))
-		return path.Join(t.remoteRoot, localRelPathNoExt), nil
+		return path.Join(t.remoteRoot, notebook.StripExtension(localRelPath)), nil
 	}
 
 	nb, _, err := notebook.DetectWithFS(t.b.SyncRoot, localRelPath)
@@ -229,9 +228,9 @@ to contain one of the following file extensions: [%s]`, literal, strings.Join(no
 		return "", ErrIsNotNotebook{localFullPath}
 	}
 
-	// Upon import, notebooks are stripped of their extension.
-	localRelPathNoExt := strings.TrimSuffix(localRelPath, path.Ext(localRelPath))
-	return path.Join(t.remoteRoot, localRelPathNoExt), nil
+	// Upon import, notebooks are stripped of their extension. Designer files
+	// keep their full ".designer.ipynb" suffix.
+	return path.Join(t.remoteRoot, notebook.StripExtension(localRelPath)), nil
 }
 
 func (t *translateContext) translateFilePath(ctx context.Context, literal, localFullPath, localRelPath string) (string, error) {

bundle/config/mutator/translate_paths_test.go

@@ -31,6 +31,15 @@ func touchNotebookFile(t *testing.T, path string) {
 	f.Close()
 }
 
+// touchDesignerFile writes a minimal valid Lakeflow Designer notebook (Jupyter
+// JSON) so that notebook.DetectWithFS recognizes it as a notebook.
+func touchDesignerFile(t *testing.T, path string) {
+	err := os.MkdirAll(filepath.Dir(path), 0o700)
+	require.NoError(t, err)
+	contents := `{"cells":[],"metadata":{"application/vnd.databricks.v1+notebook":{"language":"python"}},"nbformat":4,"nbformat_minor":0}`
+	require.NoError(t, os.WriteFile(path, []byte(contents), 0o644))
+}
+
 func touchEmptyFile(t *testing.T, path string) {
 	err := os.MkdirAll(filepath.Dir(path), 0o700)
 	require.NoError(t, err)
@@ -1124,3 +1133,110 @@ func TestTranslatePathsWithSkipLocalFileValidationDirectory(t *testing.T) {
 	// Directory path should be translated even though directory doesn't exist.
 	assert.Equal(t, "/bundle/pipeline_root", b.Config.Resources.Pipelines["pipeline"].RootPath)
 }
+
+// TestTranslatePathsDesignerNotebook verifies that Lakeflow Designer notebooks
+// (`*.designer.ipynb`) referenced by a notebook_task preserve their full
+// suffix in the deployed notebook_path, since the workspace keeps that suffix
+// on import (unlike regular `.ipynb`, which is stripped).
+func TestTranslatePathsDesignerNotebook(t *testing.T) {
+	dir := t.TempDir()
+	touchDesignerFile(t, filepath.Join(dir, "src", "designer.designer.ipynb"))
+	touchNotebookFile(t, filepath.Join(dir, "src", "regular.py"))
+
+	b := &bundle.Bundle{
+		SyncRootPath:   dir,
+		BundleRootPath: dir,
+		SyncRoot:       vfs.MustNew(dir),
+		Config: config.Root{
+			Workspace: config.Workspace{
+				FilePath: "/bundle",
+			},
+			Resources: config.Resources{
+				Jobs: map[string]*resources.Job{
+					"job": {
+						JobSettings: jobs.JobSettings{
+							Tasks: []jobs.Task{
+								{
+									NotebookTask: &jobs.NotebookTask{
+										NotebookPath: "./src/designer.designer.ipynb",
+									},
+								},
+								{
+									NotebookTask: &jobs.NotebookTask{
+										NotebookPath: "./src/regular.py",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	bundletest.SetLocation(b, ".", []dyn.Location{{File: filepath.Join(dir, "databricks.yml")}})
+
+	diags := bundle.ApplySeq(t.Context(), b, mutator.NormalizePaths(), mutator.TranslatePaths())
+	require.NoError(t, diags.Error())
+
+	// Designer notebook keeps its full ".designer.ipynb" suffix.
+	assert.Equal(t,
+		"/bundle/src/designer.designer.ipynb",
+		b.Config.Resources.Jobs["job"].Tasks[0].NotebookTask.NotebookPath)
+
+	// Regular notebook still has its extension stripped on import.
+	assert.Equal(t,
+		"/bundle/src/regular",
+		b.Config.Resources.Jobs["job"].Tasks[1].NotebookTask.NotebookPath)
+}
+
+// TestTranslatePathsDesignerNotebookSkipLocalFileValidation verifies the
+// designer-suffix preservation also holds on the config-remote-sync code path
+// where the local file is not inspected.
+func TestTranslatePathsDesignerNotebookSkipLocalFileValidation(t *testing.T) {
+	dir := t.TempDir()
+
+	b := &bundle.Bundle{
+		SyncRootPath:            dir,
+		BundleRootPath:          dir,
+		SyncRoot:                vfs.MustNew(dir),
+		SkipLocalFileValidation: true,
+		Config: config.Root{
+			Workspace: config.Workspace{
+				FilePath: "/bundle",
+			},
+			Resources: config.Resources{
+				Jobs: map[string]*resources.Job{
+					"job": {
+						JobSettings: jobs.JobSettings{
+							Tasks: []jobs.Task{
+								{
+									NotebookTask: &jobs.NotebookTask{
+										NotebookPath: "./src/designer.designer.ipynb",
+									},
+								},
+								{
+									NotebookTask: &jobs.NotebookTask{
+										NotebookPath: "./src/regular.ipynb",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	bundletest.SetLocation(b, ".", []dyn.Location{{File: filepath.Join(dir, "databricks.yml")}})
+
+	diags := bundle.ApplySeq(t.Context(), b, mutator.NormalizePaths(), mutator.TranslatePaths())
+	require.NoError(t, diags.Error())
+
+	assert.Equal(t,
+		"/bundle/src/designer.designer.ipynb",
+		b.Config.Resources.Jobs["job"].Tasks[0].NotebookTask.NotebookPath)
+	assert.Equal(t,
+		"/bundle/src/regular",
+		b.Config.Resources.Jobs["job"].Tasks[1].NotebookTask.NotebookPath)
+}

libs/notebook/ext.go

@@ -1,6 +1,11 @@
 package notebook
 
-import "github.com/databricks/databricks-sdk-go/service/workspace"
+import (
+	"path"
+	"strings"
+
+	"github.com/databricks/databricks-sdk-go/service/workspace"
+)
 
 const (
 	ExtensionNone    string = ""
@@ -9,8 +14,22 @@ const (
 	ExtensionScala   string = ".scala"
 	ExtensionSql     string = ".sql"
 	ExtensionJupyter string = ".ipynb"
+	// ExtensionDesigner is the compound suffix for Lakeflow Designer files.
+	// Unlike other notebook types, designer files keep this full suffix when
+	// imported into the workspace.
+	ExtensionDesigner string = ".designer.ipynb"
 )
 
+// StripExtension returns the workspace path for a local notebook file.
+// Designer files keep their full ".designer.ipynb" suffix in the workspace;
+// other notebook types lose their extension on import.
+func StripExtension(name string) string {
+	if strings.HasSuffix(name, ExtensionDesigner) {
+		return name
+	}
+	return strings.TrimSuffix(name, path.Ext(name))
+}
+
 // Extensions lists all notebook file extensions.
 var Extensions = []string{
 	ExtensionPython,

libs/notebook/ext_test.go

@@ -0,0 +1,32 @@
+package notebook
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStripExtension(t *testing.T) {
+	for _, tc := range []struct {
+		in   string
+		want string
+	}{
+		{"foo.py", "foo"},
+		{"foo.ipynb", "foo"},
+		{"foo.r", "foo"},
+		{"foo.scala", "foo"},
+		{"foo.sql", "foo"},
+		{"a/b/c.ipynb", "a/b/c"},
+
+		// Designer files keep their full ".designer.ipynb" suffix.
+		{"foo.designer.ipynb", "foo.designer.ipynb"},
+		{"a/b/c.designer.ipynb", "a/b/c.designer.ipynb"},
+
+		// Files without a known extension are passed through path.Ext;
+		// the last-segment extension is removed.
+		{"foo", "foo"},
+		{"foo.unknown", "foo"},
+	} {
+		assert.Equal(t, tc.want, StripExtension(tc.in), "input=%q", tc.in)
+	}
+}