1# Boundaries
2 
3**Experimental feature** - See [RFC](https://github.com/vercel/turborepo/discussions/9435)
4 
5Full docs: https://turborepo.dev/docs/reference/boundaries
6 
7Boundaries enforce package isolation by detecting:
8 
91. Imports of files outside the package's directory
102. Imports of packages not declared in `package.json` dependencies
11 
12## Usage
13 
14```bash
15turbo boundaries
16```
17 
18Run this to check for workspace violations across your monorepo.
19 
20## Tags
21 
22Tags allow you to create rules for which packages can depend on each other.
23 
24### Adding Tags to a Package
25 
26```json
27// packages/ui/turbo.json
28{
29  "tags": ["internal"]
30}
31```
32 
33### Configuring Tag Rules
34 
35Rules go in root `turbo.json`:
36 
37```json
38// turbo.json
39{
40  "boundaries": {
41    "tags": {
42      "public": {
43        "dependencies": {
44          "deny": ["internal"]
45        }
46      }
47    }
48  }
49}
50```
51 
52This prevents `public`-tagged packages from importing `internal`-tagged packages.
53 
54### Rule Types
55 
56**Allow-list approach** (only allow specific tags):
57 
58```json
59{
60  "boundaries": {
61    "tags": {
62      "public": {
63        "dependencies": {
64          "allow": ["public"]
65        }
66      }
67    }
68  }
69}
70```
71 
72**Deny-list approach** (block specific tags):
73 
74```json
75{
76  "boundaries": {
77    "tags": {
78      "public": {
79        "dependencies": {
80          "deny": ["internal"]
81        }
82      }
83    }
84  }
85}
86```
87 
88**Restrict dependents** (who can import this package):
89 
90```json
91{
92  "boundaries": {
93    "tags": {
94      "private": {
95        "dependents": {
96          "deny": ["public"]
97        }
98      }
99    }
100  }
101}
102```
103 
104### Using Package Names
105 
106Package names work in place of tags:
107 
108```json
109{
110  "boundaries": {
111    "tags": {
112      "private": {
113        "dependents": {
114          "deny": ["@repo/my-pkg"]
115        }
116      }
117    }
118  }
119}
120```
121 
122## Key Points
123 
124- Rules apply transitively (dependencies of dependencies)
125- Helps enforce architectural boundaries at scale
126- Catches violations before runtime/build errors
127