Path lexical contains

path-lexical-contains · version 1.0.0 · File paths (lexical) · free, no key needed

Check whether a child path is lexically inside a parent directory.

Use when you need to: path contains · directory containment · path traversal check.

Supported

• path contains
• directory containment
• path traversal check
• is path inside directory

Not supported

• stat file
• resolve symlinks
• filesystem access

Behavior

• Check whether child is lexically inside parent using lexicalContains.
• relative is the relative subpath from parent to child when contains:true, else null.
• A path is NOT contained if relative starts with "..".
• Paths on different drives or with mismatched absolute/relative status: contains:false.
• Default case_sensitive: true for posix, false for windows.

Input

• parent (string, required): min length 1; max length 4096
• child (string, required): min length 1; max length 4096
• format (one of "posix", "windows", "auto", optional)
• case_sensitive (boolean, optional)

Output

• contains (boolean, required)
• relative (string or null, required)
• format (one of "posix", "windows", required)

Limits

• max path bytes: 4096

Example

Request input:

{
  "parent": "/app",
  "child": "/app/src/index.js"
}

Response:

{
  "result": {
    "contains": true,
    "relative": "src/index.js",
    "format": "posix"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "path-lexical-contains",
  "version": "1.0.0",
  "input": {
    "parent": "/app",
    "child": "/app/src/index.js"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/path-lexical-contains/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"parent":"/app","child":"/app/src/index.js"}'

The machine-readable contract is at /v1/tools/path-lexical-contains/versions/1.0.0.

CLI

node cli.mjs run path-lexical-contains 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Path lexical common ancestor: Compute the deepest common ancestor directory of a set of paths.
• Path lexical sanitize: Sanitize an untrusted path to produce a safe relative path, stripping roots, drive letters, traversal segments, and illegal characters.
• Path lexical join: Join an array of path segments lexically, resolving absolute reset boundaries and normalizing separators.
• Path lexical normalize: Normalize a path lexically: collapse redundant separators, resolve "." and ".." segments.
• Path lexical parse: Decompose a file path into its lexical components without accessing the filesystem.
• Path lexical relative: Compute the lexical relative path from one path to another without filesystem access.