feat: support npm workspaces for local development

Decouple clean from build in the Makefile so that watch mode can
rebuild without wiping dist/.  Add nodemon.json and watch:build,
watch:docs, watch:pack scripts to standardize file watching.

Part of #184

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: arbrandes

.gitignore

@@ -3,6 +3,7 @@ npm-debug.log
 coverage
 /.tsbuildinfo.*
 dist/
+/.turbo
 scss
 docs/api
 

Makefile

@@ -13,7 +13,7 @@ cat_docs_command = cat ./docs/_API-header.md ./docs/_API-body.md > ./docs/API.md
 clean:
 	rm -rf dist .tsbuildinfo.*
 
-build: clean
+build:
 	tsc --build ./tsconfig.build.json
 	cp ./shell/app.scss ./dist/shell/app.scss
 

README.md

@@ -78,7 +78,7 @@ This watches for changes in `frontend-base` and rebuilds the packaged tarball on
 ```sh
 nvm use
 npm ci
-npm run pack:watch
+npm run watch:pack
 ```
 
 #### In the consuming application

docs/decisions/0010-typescript-compilation-and-local-dev-workflow.rst

@@ -122,7 +122,7 @@ To develop a local dependency (e.g., ``@openedx/frontend-base``) against a
 consuming project:
 
 1. In the dependency: ``npm run pack`` (or use a watcher like ``nodemon`` with
-   ``npm run pack:watch``)
+   ``npm run watch:pack``)
 2. In the consumer: install from the tarball and run the dev server (or use the
    `autoinstall tool`_ from the ``frontend-dev-utils`` package)
 

docs/how_tos/migrate-frontend-app.md

@@ -134,7 +134,7 @@ With the exception of any custom scripts, replace the `scripts` section of your
     "i18n_extract": "openedx formatjs extract",
     "lint": "openedx lint .",
     "lint:fix": "openedx lint --fix .",
-    "prepack": "npm run build",
+    "prepack": "npm run clean && npm run build",
     "snapshot": "openedx test --updateSnapshot",
     "test": "openedx test --coverage --passWithNoTests"
   },
@@ -158,11 +158,13 @@ Also:
 
 Last but not least, add `clean:` and `build:` targets to your `Makefile`.  The build target compiles TypeScript to JavaScript, copies all SCSS and asset files from `src/` into `dist/` preserving directory structure, and finally uses `tsc-alias` to rewrite `@src` path aliases to relative paths:
 
+Note that `build` intentionally does *not* depend on `clean`.  This allows incremental rebuilds during development (especially in workspace mode, where a watcher triggers `build` on every change).  The `prepack` script in `package.json` runs `clean && build` explicitly, so published packages always start fresh.
+
 ```makefile
 clean:
 	rm -rf dist
 
-build: clean
+build:
 	tsc --project tsconfig.build.json
 	find src -type f \( -name '*.scss' -o -path '*/assets/*' \) -exec sh -c '\
 	  for f in "$$@"; do \
@@ -250,6 +252,9 @@ node_modules
 npm-debug.log
 coverage
 dist/
+packages/
+/.turbo
+/turbo.json
 /*.tgz
 
 ### i18n ###
@@ -958,3 +963,137 @@ Refactor slots
 First, rename `src/plugin-slots`, if it exists, to `src/slots`.  Modify imports and documentation across the codebase accordingly.
 
 Next, the frontend-base equivalent to `<PluginSlot />` is `<Slot />`, and has a different API.   This includes a change in the slot ID, according to the [new slot naming ADR](../decisions/0009-slot-naming-and-lifecycle.rst) in this repository.  Rename them accordingly. You can refer to the `src/shell/dev` in this repository for examples.
+
+
+Set up npm workspaces for local development
+===========================================
+
+Frontend apps support `npm workspaces <https://docs.npmjs.com/cli/using-npm/workspaces>`_ so that developers can work on the app and its dependencies (such as ``frontend-base``) simultaneously, with changes reflected automatically.
+
+Add the workspaces field to package.json
+-----------------------------------------
+
+```diff
++ "workspaces": [
++   "packages/*"
++ ],
+```
+
+This tells npm to look in ``packages/`` for local overrides of published packages.  The ``packages/`` directory is gitignored (see the `.gitignore` step above), since it contains development-only bind-mounted checkouts.
+
+Add a turbo.site.json file
+--------------------------
+
+Create a ``turbo.site.json`` at the repository root.  This configures `Turborepo <https://turbo.build/>`_ to build workspace packages in dependency order and run persistent tasks (watch and dev server) concurrently:
+
+```json
+{
+  "$schema": "https://turbo.build/schema.json",
+  "tasks": {
+    "build": {
+      "dependsOn": ["^build"],
+      "outputs": ["dist/**"],
+      "cache": false
+    },
+    "clean": {
+      "cache": false
+    },
+    "watch:build": {
+      "dependsOn": ["^build"],
+      "persistent": true,
+      "cache": false
+    },
+    "//#dev:site": {
+      "dependsOn": ["^build"],
+      "persistent": true,
+      "cache": false
+    }
+  }
+}
+```
+
+The file is named ``turbo.site.json`` rather than ``turbo.json`` to avoid conflicts with turbo v2's workspace validation.  When a site repository includes your app as an npm workspace, turbo scans for ``turbo.json`` in each package directory and rejects root task syntax (``//#``) and configs without ``"extends"``.  By using a different filename, the config is invisible to turbo during workspace runs, and only activated via the Makefile when running standalone (see below).
+
+Add a nodemon.json file
+------------------------
+
+Create a ``nodemon.json`` at the repository root.  This configures the ``watch:build`` script to rebuild automatically when source files change:
+
+```json
+{
+  "watch": [
+    "src"
+  ],
+  "ext": "js,jsx,ts,tsx,scss"
+}
+```
+
+Add workspace-aware scripts
+----------------------------
+
+Install ``turbo`` and ``nodemon`` as dev dependencies:
+
+```sh
+npm install --save-dev turbo nodemon
+```
+
+Then add the following scripts to ``package.json``:
+
+```json
+"build:packages": "make build-packages",
+"clean:packages": "make clean-packages",
+"dev:site": "npm run dev",
+"dev:packages": "make dev-packages",
+"watch:build": "nodemon --exec 'npm run build'",
+```
+
+And add the corresponding Makefile targets:
+
+```makefile
+TURBO = TURBO_TELEMETRY_DISABLED=1 turbo --dangerously-disable-package-manager-check
+
+# turbo.site.json is the standalone turbo config for this package.  It is
+# renamed to avoid conflicts with turbo v2's workspace validation, which
+# rejects root task syntax (//#) and requires "extends" in package-level
+# turbo.json files, such as when running in a site repository. The targets
+# below copy it into place before running turbo and clean up after.
+turbo.json: turbo.site.json
+	cp $< $@
+
+build-packages: turbo.json
+	$(TURBO) run build; rm -f turbo.json
+
+clean-packages: turbo.json
+	$(TURBO) run clean; rm -f turbo.json
+
+dev-packages: turbo.json
+	$(TURBO) run watch:build dev:site; rm -f turbo.json
+```
+
+- ``watch:build`` uses ``nodemon`` to watch for source changes (as configured in ``nodemon.json``) and re-runs ``npm run build`` on each change.  Turbo runs this in each workspace package that defines it.
+- ``build:packages`` builds all workspace packages in dependency order (e.g., ``frontend-base`` before the app).
+- ``clean:packages`` runs the ``clean`` script in each workspace package.
+- ``dev:site`` is an alias for ``npm run dev`` that turbo uses as a root-only task (``//#dev:site``).
+- ``dev:packages`` builds dependencies, then concurrently watches workspace packages for changes and starts the dev server.
+
+The Makefile targets copy ``turbo.site.json`` to ``turbo.json`` before invoking turbo, then remove the copy afterward.  This ensures turbo finds its expected config when running standalone, without leaving a ``turbo.json`` that would conflict in a workspace context.  The ``--dangerously-disable-package-manager-check`` flag and ``TURBO_TELEMETRY_DISABLED=1`` are also set here, keeping turbo invocation details in one place.
+
+Using workspaces
+-----------------
+
+To develop against a local ``frontend-base``:
+
+```sh
+mkdir -p packages/frontend-base
+sudo mount --bind /path/to/frontend-base packages/frontend-base
+npm install
+npm run dev:packages
+```
+
+Bind mounts are used instead of symlinks because Node.js resolves symlinks to real paths, which breaks hoisted dependency resolution.  Docker volume mounts work equally well (and are what ``tutor dev`` uses).
+
+When done, unmount with:
+
+```sh
+sudo umount packages/frontend-base
+```

nodemon.json

@@ -0,0 +1,16 @@
+{
+  "watch": [
+    "runtime",
+    "shell",
+    "tools",
+    "index.ts",
+    "types.ts"
+  ],
+  "ext": "ts,tsx,js,jsx,json,scss,css",
+  "ignore": [
+    "node_modules/**",
+    ".git/**",
+    "pack/**"
+  ],
+  "delay": 250
+}

nodemon.pack.json

@@ -25,13 +25,14 @@
     "clean": "make clean",
     "dev": "npm run build && node ./dist/tools/cli/openedx.js dev:shell",
     "docs": "jsdoc -c jsdoc.json",
-    "docs:watch": "nodemon -w runtime -w docs/template -w README.md -e js,jsx,ts,tsx --exec npm run docs",
     "lint": "eslint .; npm run lint:tools; npm --prefix ./test-site run lint",
     "lint:tools": "cd ./tools && eslint . && cd ..",
     "pack": "mkdir -p pack && npm pack --silent --pack-destination pack >/dev/null && mv \"$(ls -t pack/*.tgz | head -n 1)\" pack/openedx-frontend-base.tgz",
-    "pack:watch": "nodemon --config nodemon.pack.json",
     "prepack": "npm run build",
-    "test": "jest"
+    "test": "jest",
+    "watch:build": "nodemon --exec 'npm run build'",
+    "watch:docs": "nodemon --watch docs/template --watch README.md --exec npm run docs",
+    "watch:pack": "nodemon --exec 'npm run pack'"
   },
   "repository": {
     "type": "git",