test(downstream): exercise released LangChain GitLoader integration

Include `langchain-community` as a current runtime GitPython user: its
published `GitLoader` requests a manual GitPython installation even though
it is absent from `Requires-Dist`. Its September download count ranks
above the other selected consumers.

Resolve the latest PyPI release and run unchanged tests from the matching
`libs/community/v{version}` tag against the editable GitPython checkout.
Use upstream test-plugin ranges and `--only-extended` so missing integration
dependencies fail collection instead of silently skipping the tests.
Add the same profile to CI and document the runtime-use selection.

The shared `uv` runner passes both GitLoader tests for release 0.4.2 on
Python 3.12 and Git 2.54. They exercise real local clones, commits,
checkout, tree traversal, ignored files, repeated loads, and remote URL
validation. No network services are used during testing and no GitPython
compatibility changes were required.

Author: codex

.github/workflows/downstream.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        project: [mlflow, bandit]
+        project: [langchain, mlflow, bandit]
     steps:
       - uses: actions/checkout@v7
         with:

test/downstream/README.md

@@ -30,6 +30,7 @@ and test-only dependencies are excluded. Downloads are not unique installations.
 
 | Project | Distribution downloads | Last tested release | Selected coverage |
 | --- | ---: | --- | --- |
+| LangChain Community | 27,882,881 | 0.4.2 | 2 upstream GitLoader tests: real clones, commits, checkout, tree traversal, ignored paths, and remote validation |
 | MLflow (`mlflow-skinny`) | 25,850,354 | 3.16.1 | 47 upstream tests: 31 repository/project/model-versioning cases plus 16 Git context and credential-redaction contract cases |
 | Bandit | 24,935,372 | 1.9.4 | 12 upstream baseline CLI tests: real repository creation, commits, branches, resets, discovery, and dirty state |
 
@@ -39,6 +40,12 @@ snapshot updated **2026-10-01 12:40:51 UTC**. Its
 covers the previous calendar month. Current metadata for the top 5,000
 distributions was checked, together with known runtime integrations.
 
+LangChain Community's published `GitLoader` integration uses GitPython at runtime
+and asks users to install it manually. It qualifies as a current user even though
+GitPython is absent from its package dependency metadata. Its upstream
+`--only-extended` option ensures missing integration dependencies fail collection
+instead of silently skipping the GitLoader tests. These tests use local fixtures.
+
 Bandit's GitPython dependency belongs to its user-facing `baseline` extra.
 Two selected tests mock error paths; the others use real repositories.
 

test/downstream/projects.json

@@ -1,4 +1,19 @@
 {
+  "langchain": {
+    "distribution": "langchain-community",
+    "source": "git",
+    "repository": "https://github.com/langchain-ai/langchain-community.git",
+    "tag": "libs/community/v{version}",
+    "cwd": "libs/community",
+    "install": [
+      "langchain-community=={version}",
+      "pytest>=8.4.1,<9",
+      "pytest-asyncio>=0.20.3,<1",
+      "blockbuster>=1.5.18,<1.6"
+    ],
+    "pytest_args": ["--only-extended"],
+    "tests": ["tests/unit_tests/document_loaders/test_git.py"]
+  },
   "mlflow": {
     "distribution": "mlflow-skinny",
     "source": "git",