[Bug]: `parse_extension_source` duplicates an existing `.git` suffix in GitHub shorthand

Is there an existing issue for the same bug?

• I have searched existing issues and this is not a duplicate.

Bug Description

In openhands-sdk/openhands/sdk/extensions/fetch.py, parse_extension_source unconditionally appends .git when expanding the github:owner/repository shorthand.

A shorthand whose repository component already has the conventional Git suffix, such as github:owner/repo.git, passes the current format validation but is expanded to:

https://github.com/owner/repo.git.git

The generated URL is not clone-equivalent to the intended repository URL. Extension fetching subsequently attempts to clone the duplicated-suffix URL instead of either normalizing it or rejecting the shorthand during parsing.

Expected Behavior

parse_extension_source should not accept a GitHub shorthand and return a duplicated .git.git clone URL.

A consistent normalization for:

parse_extension_source("github:owner/repo.git")

would be:

(SourceType.GITHUB, "https://github.com/owner/repo.git")

If an already-suffixed shorthand is intentionally unsupported, it should instead be rejected immediately with ExtensionFetchError. It should not be accepted and converted into an unusable clone URL.

Actual Behavior

parse_extension_source returns:

(SourceType.GITHUB, "https://github.com/owner/repo.git.git")

The input passes the shorthand validation because its repository component contains exactly one /. The duplicated suffix is introduced only when the normalized URL is constructed.

For a public repository, GitHub's smart-HTTP endpoint returned 200 for the canonical .git URL and 401 for the generated .git.git URL. A subsequent Git clone therefore fails instead of accessing the intended public repository.

Steps to Reproduce

1. Check out Software Agent SDK main at commit 98338ff37aea6627777b9978963ab727f51e4f40.

2. Set up the source checkout using the documented development command:

make build

3. Add the following test to tests/sdk/extensions/test_fetch.py:

def test_parse_github_shorthand_with_existing_git_suffix():
    source_type, url = parse_extension_source("github:owner/repo.git")

    assert source_type == SourceType.GITHUB
    assert url == "https://github.com/owner/repo.git"

4. Run:

uv run pytest tests/sdk/extensions/test_fetch.py -q

5. Observe that the newly added assertion fails while the 41 existing tests pass.

Acceptance Criteria

• parse_extension_source("github:owner/repo.git") does not return a URL ending in .git.git.
• An already-suffixed GitHub shorthand is either normalized to one .git suffix or rejected during parsing with a clear ExtensionFetchError.
• The existing github:owner/repo shorthand continues to normalize to https://github.com/owner/repo.git.
• Full HTTPS and SSH Git URLs ending in .git remain unchanged.
• Existing invalid-format checks for missing or excessive path components remain unchanged.
• Regression coverage includes a GitHub shorthand whose repository component already ends in .git.

Installation Method

Source checkout; development dependencies installed with make build; focused pytest reproduction

If you selected "Other", please specify

No response

SDK Version

main@98338ff37aea6627777b9978963ab727f51e4f40 (openhands-sdk 1.42.1); also reproduced at 007721b3d2bfccd1469f8008a514af13b7ae1b71

Version Confirmation

• I have confirmed this bug exists on the LATEST version of OpenHands SDK

Python Version

3.13.2

Model Name (if applicable)

Not applicable; reproduced by directly invoking deterministic extension-source parsing code

Operating System

MacOS

Logs and Error Messages

tests/sdk/extensions/test_fetch.py ..F.................................. [ 88%]
.....                                                                    [100%]

FAILED tests/sdk/extensions/test_fetch.py::test_parse_github_shorthand_with_existing_git_suffix

AssertionError: assert 'https://gith.../repo.git.git' == 'https://gith...wner/repo.git'

- https://github.com/owner/repo.git
+ https://github.com/owner/repo.git.git
?                                  ++++

1 failed, 41 passed in 0.16s

Minimal Code Sample

from openhands.sdk.extensions.fetch import parse_extension_source

result = parse_extension_source("github:owner/repo.git")

print(result)
# (<SourceType.GITHUB: 'github'>,
#  'https://github.com/owner/repo.git.git')

Screenshots and Additional Context

At the tested commit, the GitHub-shorthand branch validates only the number of path separators and then appends .git unconditionally:

if source.startswith("github:"):
    repo_path = source[7:]
    if "/" not in repo_path or repo_path.count("/") > 1:
        raise ExtensionFetchError(
            f"Invalid GitHub shorthand format: {source}. "
            f"Expected format: github:owner/repo"
        )
    url = f"https://github.com/{repo_path}.git"
    return (SourceType.GITHUB, url)

Consequently, github:owner/repo.git is treated as valid input and becomes https://github.com/owner/repo.git.git.

The same module already uses normalize_git_url for full Git URLs. That helper adds .git only when the URL does not already end with it:

if url.startswith(("https://", "http://")) and not url.endswith(".git"):
    url = url.rstrip("/")
    url = f"{url}.git"

One possible fix direction is to construct the GitHub HTTPS URL without manually adding a suffix and pass it through the existing idempotent normalizer:

url = normalize_git_url(f"https://github.com/{repo_path}")

Alternatively, the parser can explicitly reject an already-suffixed shorthand. In either case it should not return .git.git.

parse_extension_source is called by the extension-fetching path before the normalized URL is passed to the repository clone helper, so the malformed URL propagates beyond the parser.

Environment:

• OpenHands SDK: 1.42.1
• Tested snapshot: 007721b3d2bfccd1469f8008a514af13b7ae1b71
• Current main: 98338ff37aea6627777b9978963ab727f51e4f40
• Python: 3.13.2
• pytest: 9.0.3
• Operating system: macOS 15.7.3, arm64
• Installation: source checkout with the documented development setup
• Model/provider: not applicable

Start in openhands-sdk/openhands/sdk/extensions/fetch.py at parse_extension_source and review the GitHub shorthand branch alongside normalize_git_url. Run uv run pytest tests/sdk/extensions/test_fetch.py -q, then use the reported regression case to verify that suffixed and unsuffixed shorthand inputs meet the acceptance criteria without changing full Git URL handling.