fix: support repositories with pull requests disabled (MeltanoLabs#571)

## Summary

This PR lets the tap handle repositories that have pull requests
disabled.

GitHub can return `"has_pull_requests": false` in a repository payload.
For those repositories, `GET /repos/{owner}/{repo}/pulls` can return
`404 Not Found` even though the repository itself is readable and other
endpoints can still be extracted.

Instead of failing the sync for that case, the tap now skips pull
request extraction for repositories where GitHub explicitly reports that
pull requests are disabled.

## Behavior

- When `has_pull_requests` is exactly `false`, the tap skips the
`/pulls` request for that repository.
- When `has_pull_requests` is `true`, missing, `null`, `0`, or otherwise
unknown, behavior is unchanged: the tap still requests `/pulls` and
surfaces GitHub errors normally.
- The change applies only to pull request extraction.

## Implementation

- Includes GitHub's `has_pull_requests` field in repository records.
- Carries that flag to the pull request extraction step.
- Checks the flag before requesting `/repos/{owner}/{repo}/pulls`.

## What this does not change

- It does not add broad `404` or `403` tolerance.
- It does not change issue extraction or infer pull request availability
from `has_issues`.
- It does not change discussion extraction.

## Validation

```text
LOGLEVEL=WARNING uv run pytest tests/test_tap.py -k 'pull_request_capability or pull_requests_stream or issues_stream'
# 9 passed, 8 deselected

uv run ruff check tap_github/repository_streams.py tests/test_tap.py
# All checks passed

uv run mypy tap_github
# Success: no issues found in 12 source files

uv run ty check tap_github
# All checks passed

git diff --check
# passed
```
<!-- github-gate:idempotency=tap-github-pr571-body-proposal-only -->

---------

Co-authored-by: AI (Pi) <noreply@pi.dev>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 3 people

tap_github/repository_streams.py

@@ -243,6 +243,7 @@ def get_child_context(self, record: dict, context: Context | None) -> dict:
             "has_discussions": record.get(
                 "has_discussions", False
             ),  # GitHub repos not updated after the feature was released in 2021 will not have this field. # noqa: E501
+            "has_pull_requests": record.get("has_pull_requests", True),
         }
 
     def get_records(self, context: Context | None) -> Iterable[dict[str, Any]]:
@@ -324,6 +325,7 @@ def get_records(self, context: Context | None) -> Iterable[dict[str, Any]]:
         th.Property("network_count", th.IntegerType),
         th.Property("subscribers_count", th.IntegerType),
         th.Property("open_issues_count", th.IntegerType),
+        th.Property("has_pull_requests", th.BooleanType),
         th.Property("allow_squash_merge", th.BooleanType),
         th.Property("allow_merge_commit", th.BooleanType),
         th.Property("allow_rebase_merge", th.BooleanType),
@@ -1302,6 +1304,24 @@ class PullRequestsStream(GitHubRestStream):
     # GitHub is missing the "since" parameter on this endpoint.
     use_fake_since_parameter = True
 
+    def get_records(self, context: Context | None = None) -> Iterable[dict[str, Any]]:
+        """
+        Return a generator of row-type dictionary objects.
+        If pull requests are not enabled, skip the API call.
+        """
+        assert context is not None, f"Context cannot be empty for '{self.name}' stream"
+
+        repo = context.get("repo", "unknown")
+        org = context.get("org", "unknown")
+        if context.get("has_pull_requests", True) is False:
+            self.logger.debug(
+                f"Repository {org}/{repo}: Pull requests not enabled, "
+                "skipping API call",
+            )
+            return []
+
+        return super().get_records(context)
+
     def get_url_params(
         self,
         context: Context | None,

tests/test_tap.py

@@ -7,9 +7,12 @@
 import pytest
 from bs4 import BeautifulSoup
 from dateutil.parser import isoparse
+from requests import Response
+from singer_sdk.exceptions import RetriableAPIError
 from singer_sdk.helpers import _catalog as cat_helpers
 from singer_sdk.singerlib import Catalog
 
+from tap_github.repository_streams import GitHubRestStream
 from tap_github.scraping import parse_counter
 from tap_github.tap import TapGitHub
 
@@ -126,6 +129,137 @@ def test_get_a_repository_in_repo_list_mode(
     assert '"org": "meltanolabs"' not in captured_out
 
 
+def test_repository_child_context_includes_pull_request_capability(repo_list_config):  # noqa: F811
+    """Verify repository context includes the pull request capability flag."""
+    tap = TapGitHub(config=repo_list_config)
+    repository_stream = tap.streams["repositories"]
+
+    context = repository_stream.get_child_context(
+        {
+            "id": 123,
+            "name": "issues-pi",
+            "owner": {"login": "shop"},
+            "has_pull_requests": False,
+        },
+        None,
+    )
+
+    assert context["has_pull_requests"] is False
+
+
+def test_repository_child_context_defaults_pull_request_capability_to_enabled(
+    repo_list_config,  # noqa: F811
+):
+    """Preserve existing behavior when GitHub does not return the capability flag."""
+    tap = TapGitHub(config=repo_list_config)
+    repository_stream = tap.streams["repositories"]
+
+    context = repository_stream.get_child_context(
+        {
+            "id": 123,
+            "name": "tap-github",
+            "owner": {"login": "MeltanoLabs"},
+        },
+        None,
+    )
+
+    assert context["has_pull_requests"] is True
+
+
+def test_pull_requests_stream_skips_repos_with_pull_requests_disabled(
+    repo_list_config,  # noqa: F811
+):
+    """Do not call the pull requests API when repo metadata says it is disabled."""
+    tap = TapGitHub(config=repo_list_config)
+    pull_requests_stream = tap.streams["pull_requests"]
+    context = {
+        "org": "shop",
+        "repo": "issues-pi",
+        "repo_id": 123,
+        "has_pull_requests": False,
+    }
+
+    with (
+        patch.object(GitHubRestStream, "get_records") as get_records,
+        patch.object(pull_requests_stream.logger, "debug") as log_debug,
+    ):
+        records = list(pull_requests_stream.get_records(context))
+
+    assert records == []
+    get_records.assert_not_called()
+    log_debug.assert_called_once_with(
+        "Repository shop/issues-pi: Pull requests not enabled, skipping API call",
+    )
+
+
+@pytest.mark.parametrize("has_pull_requests", [True, None, 0, "missing"])
+def test_pull_requests_stream_delegates_when_pull_request_capability_is_not_false(
+    repo_list_config,  # noqa: F811
+    has_pull_requests,
+):
+    """Fail open when the capability flag is enabled, missing, or unknown."""
+    tap = TapGitHub(config=repo_list_config)
+    pull_requests_stream = tap.streams["pull_requests"]
+    context = {
+        "org": "MeltanoLabs",
+        "repo": "tap-github",
+        "repo_id": 123,
+    }
+    if has_pull_requests != "missing":
+        context["has_pull_requests"] = has_pull_requests
+
+    with patch.object(
+        GitHubRestStream,
+        "get_records",
+        return_value=iter([{"id": 456}]),
+    ) as get_records:
+        records = list(pull_requests_stream.get_records(context))
+
+    assert records == [{"id": 456}]
+    get_records.assert_called_once_with(context)
+
+
+def test_issues_stream_delegates_when_has_issues_is_false(
+    repo_list_config,  # noqa: F811
+):
+    """Do not infer issues gating from repository feature metadata."""
+    tap = TapGitHub(config=repo_list_config)
+    issues_stream = tap.streams["issues"]
+    context = {
+        "org": "shop",
+        "repo": "issues-pi",
+        "repo_id": 123,
+        "has_issues": False,
+    }
+
+    with patch.object(
+        GitHubRestStream,
+        "get_records",
+        return_value=iter([{"id": 789}]),
+    ) as get_records:
+        records = list(issues_stream.get_records(context))
+
+    assert records == [{"id": 789}]
+    get_records.assert_called_once_with(context)
+
+
+def test_pull_requests_stream_keeps_generic_404_retriable(
+    repo_list_config,  # noqa: F811
+):
+    """Pull request gating must not broaden tolerated GitHub errors."""
+    tap = TapGitHub(config=repo_list_config)
+    pull_requests_stream = tap.streams["pull_requests"]
+    response = Response()
+    response.status_code = 404
+    response.url = "https://api.github.com/repos/shop/issues-pi/pulls"
+    response.reason = "Not Found"
+    response._content = b'{"message": "Not Found"}'
+    response.headers["X-GitHub-Request-Id"] = "request-id"
+
+    with pytest.raises(RetriableAPIError, match="404 Client Error"):
+        pull_requests_stream.validate_response(response)
+
+
 @pytest.mark.repo_list(["MeltanoLabs/tap-github"])
 def test_last_state_message_is_valid(capsys, repo_list_config):  # noqa: F811
     """