diff --git a/openhands/integrations/bitbucket/__init__.py b/openhands/integrations/bitbucket/__init__.py
deleted file mode 100644
index e69de29bb2..0000000000
diff --git a/openhands/integrations/bitbucket/service/base.py b/openhands/integrations/bitbucket/service/base.py
index be135c5ca5..d7c9b4adf7 100644
--- a/openhands/integrations/bitbucket/service/base.py
+++ b/openhands/integrations/bitbucket/service/base.py
@@ -4,6 +4,7 @@ from typing import Any
 import httpx
 from pydantic import SecretStr
 
+from openhands.integrations.protocols.http_client import HTTPClient
 from openhands.integrations.service_types import (
     BaseGitService,
     OwnerType,
@@ -15,14 +16,12 @@ from openhands.integrations.service_types import (
 )
 
 
-class BitBucketMixinBase(BaseGitService):
+class BitBucketMixinBase(BaseGitService, HTTPClient):
     """
     Base mixin for BitBucket service containing common functionality
     """
 
     BASE_URL = 'https://api.bitbucket.org/2.0'
-    token: SecretStr = SecretStr('')
-    refresh = False
 
     def _extract_owner_and_repo(self, repository: str) -> tuple[str, str]:
         """Extract owner and repo from repository string.
@@ -49,7 +48,7 @@ class BitBucketMixinBase(BaseGitService):
     def _has_token_expired(self, status_code: int) -> bool:
         return status_code == 401
 
-    async def _get_bitbucket_headers(self) -> dict[str, str]:
+    async def _get_headers(self) -> dict[str, str]:
         """Get headers for Bitbucket API requests."""
         token_value = self.token.get_secret_value()
 
@@ -85,13 +84,13 @@ class BitBucketMixinBase(BaseGitService):
         """
         try:
             async with httpx.AsyncClient() as client:
-                bitbucket_headers = await self._get_bitbucket_headers()
+                bitbucket_headers = await self._get_headers()
                 response = await self.execute_request(
                     client, url, bitbucket_headers, params, method
                 )
                 if self.refresh and self._has_token_expired(response.status_code):
                     await self.get_latest_token()
-                    bitbucket_headers = await self._get_bitbucket_headers()
+                    bitbucket_headers = await self._get_headers()
                     response = await self.execute_request(
                         client=client,
                         url=url,
diff --git a/openhands/integrations/github/github_service.py b/openhands/integrations/github/github_service.py
index 01c28b0fe2..4d0eb6080f 100644
--- a/openhands/integrations/github/github_service.py
+++ b/openhands/integrations/github/github_service.py
@@ -43,8 +43,6 @@ class GitHubService(
 
     BASE_URL = 'https://api.github.com'
     GRAPHQL_URL = 'https://api.github.com/graphql'
-    token: SecretStr = SecretStr('')
-    refresh = False
 
     def __init__(
         self,
diff --git a/openhands/integrations/github/service/__init__.py b/openhands/integrations/github/service/__init__.py
index ea0bef7d64..3509f4056b 100644
--- a/openhands/integrations/github/service/__init__.py
+++ b/openhands/integrations/github/service/__init__.py
@@ -1,5 +1,6 @@
 # openhands/integrations/github/service/__init__.py
 
+from .base import GitHubMixinBase
 from .branches_prs import GitHubBranchesMixin
 from .features import GitHubFeaturesMixin
 from .prs import GitHubPRsMixin
@@ -7,6 +8,7 @@ from .repos import GitHubReposMixin
 from .resolver import GitHubResolverMixin
 
 __all__ = [
+    'GitHubMixinBase',
     'GitHubBranchesMixin',
     'GitHubFeaturesMixin',
     'GitHubPRsMixin',
diff --git a/openhands/integrations/github/service/base.py b/openhands/integrations/github/service/base.py
index 16d4f0dcce..556c647390 100644
--- a/openhands/integrations/github/service/base.py
+++ b/openhands/integrations/github/service/base.py
@@ -4,6 +4,7 @@ from typing import Any, cast
 import httpx
 from pydantic import SecretStr
 
+from openhands.integrations.protocols.http_client import HTTPClient
 from openhands.integrations.service_types import (
     BaseGitService,
     RequestMethod,
@@ -12,19 +13,15 @@ from openhands.integrations.service_types import (
 )
 
 
-class GitHubMixinBase(BaseGitService):
+class GitHubMixinBase(BaseGitService, HTTPClient):
     """
     Declares common attributes and method signatures used across mixins.
     """
 
     BASE_URL: str
     GRAPHQL_URL: str
-    token: SecretStr
-    refresh: bool
-    external_auth_id: str | None
-    base_domain: str | None
 
-    async def _get_github_headers(self) -> dict:
+    async def _get_headers(self) -> dict:
         """Retrieve the GH Token from settings store to construct the headers."""
         if not self.token:
             latest_token = await self.get_latest_token()
@@ -47,7 +44,7 @@ class GitHubMixinBase(BaseGitService):
     ) -> tuple[Any, dict]:  # type: ignore[override]
         try:
             async with httpx.AsyncClient() as client:
-                github_headers = await self._get_github_headers()
+                github_headers = await self._get_headers()
 
                 # Make initial request
                 response = await self.execute_request(
@@ -61,7 +58,7 @@ class GitHubMixinBase(BaseGitService):
                 # Handle token refresh if needed
                 if self.refresh and self._has_token_expired(response.status_code):
                     await self.get_latest_token()
-                    github_headers = await self._get_github_headers()
+                    github_headers = await self._get_headers()
                     response = await self.execute_request(
                         client=client,
                         url=url,
@@ -87,7 +84,7 @@ class GitHubMixinBase(BaseGitService):
     ) -> dict[str, Any]:
         try:
             async with httpx.AsyncClient() as client:
-                github_headers = await self._get_github_headers()
+                github_headers = await self._get_headers()
 
                 response = await client.post(
                     self.GRAPHQL_URL,
diff --git a/openhands/integrations/gitlab/gitlab_service.py b/openhands/integrations/gitlab/gitlab_service.py
index 24bb32139b..7c672b7f19 100644
--- a/openhands/integrations/gitlab/gitlab_service.py
+++ b/openhands/integrations/gitlab/gitlab_service.py
@@ -41,8 +41,6 @@ class GitLabService(
 
     BASE_URL = 'https://gitlab.com/api/v4'
     GRAPHQL_URL = 'https://gitlab.com/api/graphql'
-    token: SecretStr = SecretStr('')
-    refresh = False
 
     def __init__(
         self,
diff --git a/openhands/integrations/gitlab/service/__init__.py b/openhands/integrations/gitlab/service/__init__.py
index 94b01c2c32..b90c66ed40 100644
--- a/openhands/integrations/gitlab/service/__init__.py
+++ b/openhands/integrations/gitlab/service/__init__.py
@@ -1,5 +1,6 @@
 # openhands/integrations/gitlab/service/__init__.py
 
+from .base import GitLabMixinBase
 from .branches import GitLabBranchesMixin
 from .features import GitLabFeaturesMixin
 from .prs import GitLabPRsMixin
@@ -7,6 +8,7 @@ from .repos import GitLabReposMixin
 from .resolver import GitLabResolverMixin
 
 __all__ = [
+    'GitLabMixinBase',
     'GitLabBranchesMixin',
     'GitLabFeaturesMixin',
     'GitLabPRsMixin',
diff --git a/openhands/integrations/gitlab/service/base.py b/openhands/integrations/gitlab/service/base.py
index edbb05baae..239d972720 100644
--- a/openhands/integrations/gitlab/service/base.py
+++ b/openhands/integrations/gitlab/service/base.py
@@ -3,6 +3,7 @@ from typing import Any
 import httpx
 from pydantic import SecretStr
 
+from openhands.integrations.protocols.http_client import HTTPClient
 from openhands.integrations.service_types import (
     BaseGitService,
     RequestMethod,
@@ -11,19 +12,15 @@ from openhands.integrations.service_types import (
 )
 
 
-class GitLabMixinBase(BaseGitService):
+class GitLabMixinBase(BaseGitService, HTTPClient):
     """
     Declares common attributes and method signatures used across mixins.
     """
 
     BASE_URL: str
     GRAPHQL_URL: str
-    token: SecretStr
-    refresh: bool
-    external_auth_id: str | None
-    base_domain: str | None
 
-    async def _get_gitlab_headers(self) -> dict[str, Any]:
+    async def _get_headers(self) -> dict[str, Any]:
         """Retrieve the GitLab Token to construct the headers"""
         if not self.token:
             latest_token = await self.get_latest_token()
@@ -45,7 +42,7 @@ class GitLabMixinBase(BaseGitService):
     ) -> tuple[Any, dict]:  # type: ignore[override]
         try:
             async with httpx.AsyncClient() as client:
-                gitlab_headers = await self._get_gitlab_headers()
+                gitlab_headers = await self._get_headers()
 
                 # Make initial request
                 response = await self.execute_request(
@@ -59,7 +56,7 @@ class GitLabMixinBase(BaseGitService):
                 # Handle token refresh if needed
                 if self.refresh and self._has_token_expired(response.status_code):
                     await self.get_latest_token()
-                    gitlab_headers = await self._get_gitlab_headers()
+                    gitlab_headers = await self._get_headers()
                     response = await self.execute_request(
                         client=client,
                         url=url,
@@ -103,7 +100,7 @@ class GitLabMixinBase(BaseGitService):
             variables = {}
         try:
             async with httpx.AsyncClient() as client:
-                gitlab_headers = await self._get_gitlab_headers()
+                gitlab_headers = await self._get_headers()
                 # Add content type header for GraphQL
                 gitlab_headers['Content-Type'] = 'application/json'
 
@@ -118,7 +115,7 @@ class GitLabMixinBase(BaseGitService):
 
                 if self.refresh and self._has_token_expired(response.status_code):
                     await self.get_latest_token()
-                    gitlab_headers = await self._get_gitlab_headers()
+                    gitlab_headers = await self._get_headers()
                     gitlab_headers['Content-Type'] = 'application/json'
                     response = await client.post(
                         self.GRAPHQL_URL, headers=gitlab_headers, json=payload
diff --git a/openhands/integrations/protocols/http_client.py b/openhands/integrations/protocols/http_client.py
new file mode 100644
index 0000000000..21ec1857e0
--- /dev/null
+++ b/openhands/integrations/protocols/http_client.py
@@ -0,0 +1,99 @@
+"""HTTP Client Protocol for Git Service Integrations."""
+
+from abc import ABC, abstractmethod
+from typing import Any
+
+from httpx import AsyncClient, HTTPError, HTTPStatusError
+from pydantic import SecretStr
+
+from openhands.core.logger import openhands_logger as logger
+from openhands.integrations.service_types import (
+    AuthenticationError,
+    RateLimitError,
+    RequestMethod,
+    ResourceNotFoundError,
+    UnknownException,
+)
+
+
+class HTTPClient(ABC):
+    """Abstract base class defining the HTTP client interface for Git service integrations.
+
+    This class abstracts the common HTTP client functionality needed by all
+    Git service providers (GitHub, GitLab, BitBucket) while keeping inheritance in place.
+    """
+
+    # Default attributes (subclasses may override)
+    token: SecretStr = SecretStr('')
+    refresh: bool = False
+    external_auth_id: str | None = None
+    external_auth_token: SecretStr | None = None
+    external_token_manager: bool = False
+    base_domain: str | None = None
+
+    # Provider identification must be implemented by subclasses
+    @property
+    @abstractmethod
+    def provider(self) -> str: ...
+
+    # Abstract methods that concrete classes must implement
+    @abstractmethod
+    async def get_latest_token(self) -> SecretStr | None:
+        """Get the latest working token for the service."""
+        ...
+
+    @abstractmethod
+    async def _get_headers(self) -> dict[str, Any]:
+        """Get HTTP headers for API requests."""
+        ...
+
+    @abstractmethod
+    async def _make_request(
+        self,
+        url: str,
+        params: dict | None = None,
+        method: RequestMethod = RequestMethod.GET,
+    ) -> tuple[Any, dict]:
+        """Make an HTTP request to the Git service API."""
+        ...
+
+    def _has_token_expired(self, status_code: int) -> bool:
+        """Check if the token has expired based on HTTP status code."""
+        return status_code == 401
+
+    async def execute_request(
+        self,
+        client: AsyncClient,
+        url: str,
+        headers: dict,
+        params: dict | None,
+        method: RequestMethod = RequestMethod.GET,
+    ):
+        """Execute an HTTP request using the provided client."""
+        if method == RequestMethod.POST:
+            return await client.post(url, headers=headers, json=params)
+        return await client.get(url, headers=headers, params=params)
+
+    def handle_http_status_error(
+        self, e: HTTPStatusError
+    ) -> (
+        AuthenticationError | RateLimitError | ResourceNotFoundError | UnknownException
+    ):
+        """Handle HTTP status errors and convert them to appropriate exceptions."""
+        if e.response.status_code == 401:
+            return AuthenticationError(f'Invalid {self.provider} token')
+        elif e.response.status_code == 404:
+            return ResourceNotFoundError(
+                f'Resource not found on {self.provider} API: {e}'
+            )
+        elif e.response.status_code == 429:
+            logger.warning(f'Rate limit exceeded on {self.provider} API: {e}')
+            return RateLimitError(f'{self.provider} API rate limit exceeded')
+
+        logger.warning(f'Status error on {self.provider} API: {e}')
+        return UnknownException(f'Unknown error: {e}')
+
+    def handle_http_error(self, e: HTTPError) -> UnknownException:
+        """Handle general HTTP errors."""
+        logger.warning(f'HTTP error on {self.provider} API: {type(e).__name__} : {e}')
+        return UnknownException(f'HTTP error {type(e).__name__} : {e}')
diff --git a/openhands/integrations/service_types.py b/openhands/integrations/service_types.py
index 613ee69270..9c22c660a8 100644
--- a/openhands/integrations/service_types.py
+++ b/openhands/integrations/service_types.py
@@ -4,7 +4,6 @@ from enum import Enum
 from pathlib import Path
 from typing import Any, Protocol
 
-from httpx import AsyncClient, HTTPError, HTTPStatusError
 from jinja2 import Environment, FileSystemLoader
 from pydantic import BaseModel, SecretStr
 
@@ -242,40 +241,6 @@ class BaseGitService(ABC):
         """Extract file path from directory item."""
         ...
 
-    async def execute_request(
-        self,
-        client: AsyncClient,
-        url: str,
-        headers: dict,
-        params: dict | None,
-        method: RequestMethod = RequestMethod.GET,
-    ):
-        if method == RequestMethod.POST:
-            return await client.post(url, headers=headers, json=params)
-        return await client.get(url, headers=headers, params=params)
-
-    def handle_http_status_error(
-        self, e: HTTPStatusError
-    ) -> (
-        AuthenticationError | RateLimitError | ResourceNotFoundError | UnknownException
-    ):
-        if e.response.status_code == 401:
-            return AuthenticationError(f'Invalid {self.provider} token')
-        elif e.response.status_code == 404:
-            return ResourceNotFoundError(
-                f'Resource not found on {self.provider} API: {e}'
-            )
-        elif e.response.status_code == 429:
-            logger.warning(f'Rate limit exceeded on {self.provider} API: {e}')
-            return RateLimitError('GitHub API rate limit exceeded')
-
-        logger.warning(f'Status error on {self.provider} API: {e}')
-        return UnknownException(f'Unknown error: {e}')
-
-    def handle_http_error(self, e: HTTPError) -> UnknownException:
-        logger.warning(f'HTTP error on {self.provider} API: {type(e).__name__} : {e}')
-        return UnknownException(f'HTTP error {type(e).__name__} : {e}')
-
     def _determine_microagents_path(self, repository_name: str) -> str:
         """Determine the microagents directory path based on repository name."""
         actual_repo_name = repository_name.split('/')[-1]
@@ -462,9 +427,6 @@ class BaseGitService(ABC):
             return comment_body[:max_comment_length] + '...'
         return comment_body
 
-    def _has_token_expired(self, status_code: int) -> bool:
-        return status_code == 401
-
 
 class InstallationsService(Protocol):
     async def get_installations(self) -> list[str]:
diff --git a/tests/unit/integrations/github/test_github_service.py b/tests/unit/integrations/github/test_github_service.py
index 0248e5f396..9e059e5e2c 100644
--- a/tests/unit/integrations/github/test_github_service.py
+++ b/tests/unit/integrations/github/test_github_service.py
@@ -24,7 +24,7 @@ async def test_github_service_token_handling():
     assert service.token.get_secret_value() == 'test-token'
 
     # Test headers contain the token correctly
-    headers = await service._get_github_headers()
+    headers = await service._get_headers()
     assert headers['Authorization'] == 'Bearer test-token'
     assert headers['Accept'] == 'application/vnd.github.v3+json'
 
diff --git a/tests/unit/integrations/protocols/test_http_client.py b/tests/unit/integrations/protocols/test_http_client.py
new file mode 100644
index 0000000000..1210d34344
--- /dev/null
+++ b/tests/unit/integrations/protocols/test_http_client.py
@@ -0,0 +1,309 @@
+"""Unit tests for HTTPClient abstract base class (ABC)."""
+
+from typing import Any
+from unittest.mock import AsyncMock, Mock
+
+import httpx
+import pytest
+from pydantic import SecretStr
+
+from openhands.integrations.protocols.http_client import HTTPClient
+from openhands.integrations.service_types import (
+    AuthenticationError,
+    RateLimitError,
+    RequestMethod,
+    ResourceNotFoundError,
+    UnknownException,
+)
+
+
+class TestableHTTPClient(HTTPClient):
+    """Testable concrete implementation of HTTPClient for unit testing."""
+
+    def __init__(self, provider_name: str = 'test-provider'):
+        self.token = SecretStr('test-token')
+        self.refresh = False
+        self.external_auth_id = None
+        self.external_auth_token = None
+        self.external_token_manager = False
+        self.base_domain = None
+        self._provider_name = provider_name
+
+    @property
+    def provider(self) -> str:
+        return self._provider_name
+
+    @provider.setter
+    def provider(self, value: str) -> None:
+        self._provider_name = value
+
+    async def get_latest_token(self) -> SecretStr | None:
+        return self.token
+
+    async def _get_headers(self) -> dict[str, Any]:
+        return {'Authorization': f'Bearer {self.token.get_secret_value()}'}
+
+    async def _make_request(
+        self,
+        url: str,
+        params: dict | None = None,
+        method: RequestMethod = RequestMethod.GET,
+    ):
+        # Mock implementation for testing
+        return {'test': 'data'}, {}
+
+
+@pytest.mark.asyncio
+class TestHTTPClient:
+    """Test cases for HTTPClient ABC."""
+
+    def setup_method(self):
+        """Set up test fixtures."""
+        self.client = TestableHTTPClient()
+
+    def test_default_attributes(self):
+        """Test default attribute values."""
+        assert isinstance(self.client.token, SecretStr)
+        assert self.client.refresh is False
+        assert self.client.external_auth_id is None
+        assert self.client.external_auth_token is None
+        assert self.client.external_token_manager is False
+        assert self.client.base_domain is None
+
+    def test_provider_property(self):
+        """Test provider property."""
+        assert self.client.provider == 'test-provider'
+
+    def test_has_token_expired_default_implementation(self):
+        """Test default _has_token_expired implementation."""
+        # The TestableHTTPClient inherits the default implementation from the protocol
+        client = TestableHTTPClient()
+
+        assert client._has_token_expired(401) is True
+        assert client._has_token_expired(200) is False
+        assert client._has_token_expired(404) is False
+        assert client._has_token_expired(500) is False
+
+    async def test_execute_request_get(self):
+        """Test execute_request with GET method."""
+        client = TestableHTTPClient()
+
+        mock_client = AsyncMock()
+        mock_response = AsyncMock()
+        mock_client.get.return_value = mock_response
+
+        url = 'https://api.example.com/user'
+        headers = {'Authorization': 'Bearer token'}
+        params = {'per_page': 10}
+
+        result = await client.execute_request(
+            mock_client, url, headers, params, RequestMethod.GET
+        )
+
+        assert result == mock_response
+        mock_client.get.assert_called_once_with(url, headers=headers, params=params)
+
+    async def test_execute_request_post(self):
+        """Test execute_request with POST method."""
+        client = TestableHTTPClient()
+
+        mock_client = AsyncMock()
+        mock_response = AsyncMock()
+        mock_client.post.return_value = mock_response
+
+        url = 'https://api.example.com/issues'
+        headers = {'Authorization': 'Bearer token'}
+        params = {'title': 'Test Issue'}
+
+        result = await client.execute_request(
+            mock_client, url, headers, params, RequestMethod.POST
+        )
+
+        assert result == mock_response
+        mock_client.post.assert_called_once_with(url, headers=headers, json=params)
+
+    def test_handle_http_status_error_401(self):
+        """Test handling of 401 HTTP status error."""
+        client = TestableHTTPClient('github')
+
+        mock_response = Mock()
+        mock_response.status_code = 401
+
+        error = httpx.HTTPStatusError(
+            message='401 Unauthorized', request=Mock(), response=mock_response
+        )
+
+        result = client.handle_http_status_error(error)
+        assert isinstance(result, AuthenticationError)
+        assert 'Invalid github token' in str(result)
+
+    def test_handle_http_status_error_404(self):
+        """Test handling of 404 HTTP status error."""
+        client = TestableHTTPClient()
+        client.provider = 'gitlab'
+
+        mock_response = Mock()
+        mock_response.status_code = 404
+
+        error = httpx.HTTPStatusError(
+            message='404 Not Found', request=Mock(), response=mock_response
+        )
+
+        result = client.handle_http_status_error(error)
+        assert isinstance(result, ResourceNotFoundError)
+        assert 'Resource not found on gitlab API' in str(result)
+
+    def test_handle_http_status_error_429(self):
+        """Test handling of 429 HTTP status error."""
+        client = TestableHTTPClient()
+        client.provider = 'bitbucket'
+
+        mock_response = Mock()
+        mock_response.status_code = 429
+
+        error = httpx.HTTPStatusError(
+            message='429 Too Many Requests', request=Mock(), response=mock_response
+        )
+
+        result = client.handle_http_status_error(error)
+        assert isinstance(result, RateLimitError)
+        assert 'bitbucket API rate limit exceeded' in str(result)
+
+    def test_handle_http_status_error_other(self):
+        """Test handling of other HTTP status errors."""
+        client = TestableHTTPClient()
+        client.provider = 'test-provider'
+
+        mock_response = Mock()
+        mock_response.status_code = 500
+
+        error = httpx.HTTPStatusError(
+            message='500 Internal Server Error', request=Mock(), response=mock_response
+        )
+
+        result = client.handle_http_status_error(error)
+        assert isinstance(result, UnknownException)
+        assert 'Unknown error' in str(result)
+
+    def test_handle_http_error(self):
+        """Test handling of general HTTP errors."""
+        client = TestableHTTPClient()
+        client.provider = 'test-provider'
+
+        error = httpx.ConnectError('Connection failed')
+
+        result = client.handle_http_error(error)
+        assert isinstance(result, UnknownException)
+        assert 'HTTP error ConnectError' in str(result)
+
+    def test_handle_http_error_with_different_error_types(self):
+        """Test handling of different HTTP error types."""
+        client = TestableHTTPClient()
+        client.provider = 'test-provider'
+
+        # Test with different error types
+        errors = [
+            httpx.ConnectError('Connection failed'),
+            httpx.TimeoutException('Request timed out'),
+            httpx.ReadTimeout('Read timeout'),
+            httpx.WriteTimeout('Write timeout'),
+        ]
+
+        for error in errors:
+            result = client.handle_http_error(error)
+            assert isinstance(result, UnknownException)
+            assert f'HTTP error {type(error).__name__}' in str(result)
+
+    def test_runtime_checkable(self):
+        """Test that HTTPClient is runtime checkable."""
+        from openhands.integrations.protocols.http_client import HTTPClient
+
+        # Test that our testable client implements the protocol
+        assert isinstance(self.client, HTTPClient)
+
+        # Test that a class without the required methods doesn't implement the protocol
+        class IncompleteClient:
+            pass
+
+        incomplete = IncompleteClient()
+        assert not isinstance(incomplete, HTTPClient)
+
+    def test_protocol_attributes_exist(self):
+        """Test that protocol defines expected attributes."""
+        client = TestableHTTPClient()
+
+        # Test default attribute values from protocol
+        assert hasattr(client, 'token')
+        assert hasattr(client, 'refresh')
+        assert hasattr(client, 'external_auth_id')
+        assert hasattr(client, 'external_auth_token')
+        assert hasattr(client, 'external_token_manager')
+        assert hasattr(client, 'base_domain')
+
+        # Test TestableHTTPClient values
+        assert client.token == SecretStr('test-token')
+        assert client.refresh is False
+        assert client.external_auth_id is None
+        assert client.external_auth_token is None
+        assert client.external_token_manager is False
+        assert client.base_domain is None
+
+    def test_protocol_methods_exist(self):
+        """Test that protocol defines expected methods."""
+        client = TestableHTTPClient()
+
+        # Test that methods exist
+        assert hasattr(client, 'get_latest_token')
+        assert hasattr(client, '_get_headers')
+        assert hasattr(client, '_make_request')
+        assert hasattr(client, '_has_token_expired')
+        assert hasattr(client, 'execute_request')
+        assert hasattr(client, 'handle_http_status_error')
+        assert hasattr(client, 'handle_http_error')
+        assert hasattr(client, 'provider')
+
+    def test_protocol_concrete_methods_work(self):
+        """Test that concrete protocol methods work correctly."""
+        client = TestableHTTPClient()
+
+        # These methods should work since TestableHTTPClient implements them
+        assert client.provider == 'test-provider'
+
+        # Test that the default implementations from the protocol are available
+        assert hasattr(client, '_has_token_expired')
+        assert hasattr(client, 'execute_request')
+        assert hasattr(client, 'handle_http_status_error')
+        assert hasattr(client, 'handle_http_error')
+
+    def test_provider_specific_error_messages(self):
+        """Test that error messages are provider-specific."""
+        providers = ['github', 'gitlab', 'bitbucket']
+
+        for provider in providers:
+            client = TestableHTTPClient()
+            client.provider = provider
+
+            # Test 401 error
+            mock_response = Mock()
+            mock_response.status_code = 401
+            error = httpx.HTTPStatusError(
+                message='401 Unauthorized', request=Mock(), response=mock_response
+            )
+            result = client.handle_http_status_error(error)
+            assert f'Invalid {provider} token' in str(result)
+
+            # Test 404 error
+            mock_response.status_code = 404
+            error = httpx.HTTPStatusError(
+                message='404 Not Found', request=Mock(), response=mock_response
+            )
+            result = client.handle_http_status_error(error)
+            assert f'Resource not found on {provider} API' in str(result)
+
+            # Test 429 error
+            mock_response.status_code = 429
+            error = httpx.HTTPStatusError(
+                message='429 Too Many Requests', request=Mock(), response=mock_response
+            )
+            result = client.handle_http_status_error(error)
+            assert f'{provider} API rate limit exceeded' in str(result)