UV Workspaces

Quick reference for managing monorepo and multi-package projects with UV workspaces.

When to Use This Skill

Use this skill when...	Use another skill instead when...
Setting up a Python monorepo with shared deps	Managing a single package (`uv-project-management`)
Configuring workspace members and inter-package deps	Adding git/URL dependencies (`uv-advanced-dependencies`)
Using `--package` or `--all-packages` flags	Building/publishing to PyPI (`python-packaging`)
Creating virtual workspaces (root with no project)	Managing Python versions (`uv-python-versions`)
Debugging workspace dependency resolution	Running standalone scripts (`uv-run`)

Quick Reference

Workspace Structure

my-workspace/
├── pyproject.toml          # Root workspace config
├── uv.lock                 # Shared lockfile (all members)
├── packages/
│   ├── core/
│   │   ├── pyproject.toml
│   │   └── src/core/
│   ├── api/
│   │   ├── pyproject.toml
│   │   └── src/api/
│   └── cli/
│       ├── pyproject.toml
│       └── src/cli/
└── README.md

Root pyproject.toml

[project]
name = "my-workspace"
version = "0.1.0"
requires-python = ">=3.11"

[tool.uv.workspace]
members = ["packages/*"]

# Optional: exclude specific members
exclude = ["packages/experimental"]

Virtual Workspace (No Root Package)

When the root is purely organizational and not a package itself, omit the [project] table:

# Root pyproject.toml — virtual workspace (no [project] table)
[tool.uv.workspace]
members = ["packages/*"]

The root is not a workspace member
All members live in subdirectories
uv run and uv sync require --package or --all-packages (will error without them)

Member pyproject.toml

[project]
name = "my-api"
version = "0.1.0"
requires-python = ">=3.11"
dependencies = [
    "my-core",       # Workspace member
    "fastapi",       # External (PyPI)
]

[tool.uv.sources]
my-core = { workspace = true }

Common Commands

Operation	Command
Sync workspace root	`uv sync`
Sync all members	`uv sync --all-packages`
Sync specific member	`uv sync --package my-api`
Run in member context	`uv run --package my-api python script.py`
Lock entire workspace	`uv lock`
Upgrade a dependency	`uv lock --upgrade-package requests`
Build specific package	`uv build --package my-core`
Add dep to member	`cd packages/api && uv add requests`
Add workspace dep	`cd packages/api && uv add ../core`

Key Behaviors

Source Inheritance

Root tool.uv.sources apply to all members unless overridden.

Use case: Define workspace sources in root for all members, override only when a specific member needs a different version:

# Root pyproject.toml — applies to all members
[tool.uv.sources]
my-utils = { workspace = true }

# packages/legacy/pyproject.toml — needs pinned version
[tool.uv.sources]
my-utils = { path = "../utils-v1" }  # Overrides root entirely

Override is per-dependency and total — if a member defines a source for a dependency, the root source for that dependency is ignored completely.

requires-python Resolution

The workspace enforces the intersection of all members' requires-python:

# packages/core: requires-python = ">=3.10"
# packages/api:  requires-python = ">=3.11"
# Effective:     requires-python = ">=3.11"

All members must have compatible Python version requirements.

Editable Installations

Workspace member dependencies are always editable — source changes are immediately available without reinstallation.

Default Scope

Command	Default scope	Override
`uv lock`	Entire workspace	—
`uv sync`	Workspace root only	`--package`, `--all-packages`
`uv run`	Workspace root only	`--package`, `--all-packages`
`uv build`	All members	`--package`

Workspace vs Path Dependencies

Feature	`{ workspace = true }`	`{ path = "../pkg" }`
Shared lockfile	Yes	No
Always editable	Yes	Optional
Must be workspace member	Yes	No
`--package` flag works	Yes	No
Conflicting deps allowed	No	Yes

Use path dependencies when members need conflicting requirements or separate virtual environments.

Docker Layer Caching

# Install deps first (cached layer)
COPY pyproject.toml uv.lock packages/*/pyproject.toml ./
RUN uv sync --frozen --no-install-workspace

# Then install project (changes frequently)
COPY . .
RUN uv sync --frozen

Flag	Effect
`--no-install-project`	Skip current project, install deps only
`--no-install-workspace`	Skip all workspace members, install deps only
`--no-install-package <name>`	Skip specific package(s)
`--frozen`	Skip lockfile freshness check

Agentic Optimizations

Context	Command
Sync all members	`uv sync --all-packages`
CI sync (frozen)	`uv sync --all-packages --frozen`
Test specific member	`uv run --package my-core pytest --dots --bail=1`
Test all members	`uv run --all-packages pytest --dots --bail=1`
Lock with upgrade	`uv lock --upgrade-package <dep>`
Build one package	`uv build --package my-core`
Docker deps layer	`uv sync --frozen --no-install-workspace`

uv-workspaces