Fetch GitHub File

Fetch source code from GitHub URLs using the gh CLI for reliable, authenticated access.

URL Patterns

Parse the GitHub URL to determine what to fetch:

URL Pattern	Type	Action
`github.com/owner/repo/blob/ref/path`	File	Fetch file contents
`github.com/owner/repo/blob/ref/path#L10`	File + line	Fetch file, show from line 10
`github.com/owner/repo/blob/ref/path#L10-L25`	File + range	Fetch file, show lines 10-25
`github.com/owner/repo/tree/ref/path`	Directory	List directory contents
`github.com/owner/repo/tree/ref`	Root	List repository root
`github.com/owner/repo`	Repository	Offer to clone or list root

Fetching Files

Use the GitHub API via gh to fetch file contents:

bash

# Fetch file content (returns JSON with base64-encoded content)
# IMPORTANT: Quote the URL to prevent shell interpretation of ?
gh api 'repos/{owner}/{repo}/contents/{path}?ref={ref}'

To decode and display:

bash

gh api 'repos/{owner}/{repo}/contents/{path}?ref={ref}' --jq '.content' | base64 -d

Line Ranges

If the URL includes a line range like #L10-L25:

•Fetch the full file
•Extract and display only the specified lines
•Show the line numbers for context

Example output format:

code

# src/utils/parser.ts (lines 10-25)

10: export function parseUrl(url: string): ParsedUrl {
11:   const match = url.match(GITHUB_PATTERN);
...

Fetching Directories

For directory URLs, list the contents:

bash

gh api 'repos/{owner}/{repo}/contents/{path}?ref={ref}' --jq '.[] | "\(.type)\t\(.name)"'

Display as a tree structure showing files and subdirectories. Offer to fetch specific files if the user wants to explore further.

Cloning Repositories

For full repository access (exploring multiple files, understanding structure):

bash

# Clone to a temporary directory
TEMP_DIR=$(mktemp -d)
gh repo clone {owner}/{repo} "$TEMP_DIR" -- --depth 1 --branch {ref}
echo "Cloned to: $TEMP_DIR"

Use shallow clone (--depth 1) by default for speed. After cloning:

•List the directory structure
•Read files as requested
•Remember the temp directory path for subsequent requests

URL Parsing

Extract components from GitHub URLs:

code

https://github.com/anthropics/claude-code/blob/main/src/index.ts#L10-L25
         ^^^^^^^^^ ^^^^^^^^^^^ ^^^^ ^^^^ ^^^^^^^^^^^^^ ^^^^^^^^
         |         |           |    |    |             |
         |         |           |    |    path          line range
         |         |           |    ref (branch/tag/commit)
         |         |           "blob" = file, "tree" = directory
         |         repo
         owner

Error Handling

•404: File/path doesn't exist. Check spelling and ref.
•403: Rate limited or private repo. Ensure gh auth status is valid.
•Large files: If content is null and download_url is present, file is too large for API. Use download_url directly.

Workflow

•Parse the URL - Extract owner, repo, ref, path, and line range
•Determine type - File (blob) or directory (tree)
•Fetch via gh API - Use authenticated API access
•Format output - Show file contents with line numbers, or directory listing
•Offer next steps - "Want me to fetch another file?" or "Should I clone the repo for deeper exploration?"

Examples

User pastes: https://github.com/anthropics/claude-code/blob/main/src/index.ts#L1-L50

Response:

•Parse: owner=anthropics, repo=claude-code, ref=main, path=src/index.ts, lines=1-50
•Fetch: gh api repos/anthropics/claude-code/contents/src/index.ts?ref=main
•Decode base64 content
•Display lines 1-50 with line numbers

User pastes: https://github.com/anthropics/claude-code/tree/main/src

Response:

•Parse: owner=anthropics, repo=claude-code, ref=main, path=src
•Fetch: gh api repos/anthropics/claude-code/contents/src?ref=main
•Display directory listing
•Offer to fetch specific files