feat(integrations): add base classes and exceptions

src/arbiter/integrations/__init__.py

@@ -0,0 +1,33 @@
+"""Platform integration clients for GitHub and GitLab."""
+
+from arbiter.integrations.base import (
+    CommitStatus,
+    Platform,
+    PlatformClient,
+    PullRequestInfo,
+)
+from arbiter.integrations.exceptions import (
+    AuthenticationError,
+    IntegrationError,
+    NotFoundError,
+    PlatformError,
+    RateLimitError,
+)
+from arbiter.integrations.formatters import ReviewCommentFormatter
+from arbiter.integrations.github import GitHubClient
+from arbiter.integrations.gitlab import GitLabClient
+
+__all__ = [
+    "AuthenticationError",
+    "CommitStatus",
+    "GitHubClient",
+    "GitLabClient",
+    "IntegrationError",
+    "NotFoundError",
+    "Platform",
+    "PlatformClient",
+    "PlatformError",
+    "PullRequestInfo",
+    "RateLimitError",
+    "ReviewCommentFormatter",
+]

src/arbiter/integrations/base.py

@@ -0,0 +1,92 @@
+"""Base classes and types for platform integrations."""
+
+from abc import ABC, abstractmethod
+from datetime import datetime
+from enum import StrEnum
+
+from pydantic import BaseModel, Field
+
+
+class Platform(StrEnum):
+    """Supported code hosting platforms."""
+
+    GITHUB = "github"
+    GITLAB = "gitlab"
+
+
+class CommitStatus(StrEnum):
+    """Commit status states for PR checks."""
+
+    PENDING = "pending"
+    SUCCESS = "success"
+    FAILURE = "failure"
+    ERROR = "error"
+
+
+class PullRequestInfo(BaseModel):
+    """Information about a pull request or merge request."""
+
+    platform: Platform = Field(description="Source platform")
+    repository: str = Field(description="Repository name (owner/repo format)")
+    pr_number: int = Field(description="PR/MR number")
+    head_sha: str = Field(description="Head commit SHA")
+    base_sha: str = Field(description="Base commit SHA")
+    head_ref: str = Field(description="Head branch name")
+    base_ref: str = Field(description="Base branch name")
+    title: str = Field(description="PR/MR title")
+    author: str | None = Field(default=None, description="PR/MR author username")
+    url: str = Field(description="Web URL to the PR/MR")
+    is_draft: bool = Field(default=False, description="Whether PR/MR is a draft")
+
+
+class Comment(BaseModel):
+    """A comment on a pull request or merge request."""
+
+    id: str = Field(description="Comment ID on the platform")
+    body: str = Field(description="Comment body text")
+    author: str = Field(description="Comment author username")
+    url: str = Field(description="Web URL to the comment")
+    created_at: datetime = Field(description="When the comment was created")
+
+
+class PlatformClient(ABC):
+    @property
+    @abstractmethod
+    def platform(self) -> Platform: ...
+
+    @abstractmethod
+    async def get_pr_diff(self, repository: str, pr_number: int) -> str: ...
+
+    @abstractmethod
+    async def post_comment(self, repository: str, pr_number: int, body: str) -> str: ...
+
+    @abstractmethod
+    async def update_commit_status(
+        self,
+        repository: str,
+        sha: str,
+        status: CommitStatus,
+        description: str,
+        context: str,
+        target_url: str | None = None,
+    ) -> None: ...
+
+    @abstractmethod
+    async def get_pr_info(self, repository: str, pr_number: int) -> PullRequestInfo: ...
+
+    @abstractmethod
+    async def get_comments(self, repository: str, pr_number: int) -> list[Comment]: ...
+
+    @abstractmethod
+    async def update_comment(
+        self, repository: str, pr_number: int, comment_id: str, body: str
+    ) -> str: ...
+
+    @abstractmethod
+    async def close(self) -> None: ...
+
+    async def __aenter__(self) -> "PlatformClient":
+        return self
+
+    async def __aexit__(self, *args: object) -> None:
+        await self.close()

src/arbiter/integrations/exceptions.py

@@ -0,0 +1,47 @@
+"""Exception types for platform integrations."""
+
+
+class IntegrationError(Exception):
+    """Base exception for all platform integration errors."""
+
+    def __init__(
+        self,
+        message: str,
+        status_code: int | None = None,
+        response_body: str | None = None,
+    ) -> None:
+        super().__init__(message)
+        self.status_code = status_code
+        self.response_body = response_body
+
+
+class AuthenticationError(IntegrationError):
+    """Raised on 401 Unauthorized or 403 Forbidden responses."""
+
+    pass
+
+
+class RateLimitError(IntegrationError):
+    """Raised on 429 Too Many Requests responses."""
+
+    def __init__(
+        self,
+        message: str,
+        retry_after: int | None = None,
+        status_code: int | None = 429,
+        response_body: str | None = None,
+    ) -> None:
+        super().__init__(message, status_code, response_body)
+        self.retry_after = retry_after
+
+
+class NotFoundError(IntegrationError):
+    """Raised on 404 Not Found responses."""
+
+    pass
+
+
+class PlatformError(IntegrationError):
+    """Raised on 5xx server errors."""
+
+    pass