diff --git a/.github/workflows/check-pr.yaml b/.github/workflows/check-pr.yaml
index 3b6902a..919a6ca 100644
--- a/.github/workflows/check-pr.yaml
+++ b/.github/workflows/check-pr.yaml
@@ -45,3 +45,7 @@ jobs:
         working-directory: backend
         run: |
           task test-container
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          TELEGRAM_TOKEN: ${{ secrets.TELEGRAM_TOKEN }}
+          TELEGRAM_CHAT_ID: ${{ secrets.TELEGRAM_CHAT_ID }}
diff --git a/.prettierignore b/.prettierignore
index ef8fb06..7e1eb12 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -9,6 +9,7 @@ __pycache__/
 .pytest_cache/
 .ruff_cache/
 .coverage/
+htmlcov/
 
 # Backend temporary files
 backend/example/state
diff --git a/backend/Taskfile.yaml b/backend/Taskfile.yaml
index 46beb1a..f53a96f 100644
--- a/backend/Taskfile.yaml
+++ b/backend/Taskfile.yaml
@@ -143,7 +143,7 @@ tasks:
     cmds:
       - echo 'Running pytest...'
       - task: _python
-        vars: { COMMAND: "-m pytest" }
+        vars: { COMMAND: "-m pytest {{.CLI_ARGS}}" }
 
   test-container:
     desc: Run tests in container
diff --git a/backend/lib/github/clients/gql.py b/backend/lib/github/clients/gql.py
index cfc7d78..5d5e816 100644
--- a/backend/lib/github/clients/gql.py
+++ b/backend/lib/github/clients/gql.py
@@ -12,19 +12,22 @@
 import pydantic.alias_generators as pydantic_alias_generators
 
 import lib.github.models as github_models
+import lib.utils.pydantic as pydantic_utils
 
 logger = logging.getLogger(__name__)
 
 
 class BaseRequest(abc.ABC):
-    document: graphql.DocumentNode = NotImplemented
+    @property
+    @abc.abstractmethod
+    def document(self) -> graphql.DocumentNode: ...
 
     @property
     def params(self) -> dict[str, typing.Any]:
         raise NotImplementedError
 
 
-class BaseModel(pydantic.BaseModel):
+class BaseModel(pydantic_utils.BaseModel):
     model_config = pydantic.ConfigDict(alias_generator=pydantic_alias_generators.to_camel)
 
 
@@ -33,32 +36,34 @@ def to_dataclass(self) -> typing.Any:
         raise NotImplementedError
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class GetRepositoriesRequest(BaseRequest):
     owner: str
     limit: int = 100
     after: str | None = None
 
-    document: graphql.DocumentNode = gql.gql(
-        """
-        query myOrgRepos($query: String!, $limit: Int!, $after: String) {
-            search(query: $query, type: REPOSITORY, first: $limit, after: $after) {
-                nodes {
-                    ... on Repository {
-                        name
-                        owner {
-                            login
+    @property
+    def document(self) -> graphql.DocumentNode:
+        return gql.gql(
+            """
+            query myOrgRepos($query: String!, $limit: Int!, $after: String) {
+                search(query: $query, type: REPOSITORY, first: $limit, after: $after) {
+                    nodes {
+                        ... on Repository {
+                            name
+                            owner {
+                                login
+                            }
                         }
                     }
-                }
-                pageInfo {
-                    endCursor
-                    hasNextPage
+                    pageInfo {
+                        endCursor
+                        hasNextPage
+                    }
                 }
             }
-        }
-        """
-    )
+            """
+        )
 
     @property
     def params(self) -> dict[str, typing.Any]:
@@ -79,7 +84,7 @@ class Owner(BaseModel):
             owner: Owner
 
         class PageInfo(BaseModel):
-            end_cursor: str
+            end_cursor: str | None
             has_next_page: bool
 
         nodes: list[Repository]
@@ -97,33 +102,35 @@ def to_dataclass(self) -> list[github_models.Repository]:
         ]
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class GetRepositoryIssuesRequest(BaseRequest):
     owner: str
     repository: str
     created_after: datetime.datetime
     limit: int = 100
 
-    document: graphql.DocumentNode = gql.gql(
-        """
-        query getIssues($query: String!, $limit: Int!) {
-            search(query: $query, type: ISSUE, first: $limit) {
-                nodes {
-                    ... on Issue {
-                        id
-                        url
-                        title
-                        body
-                        createdAt
-                        author {
-                            login
+    @property
+    def document(self) -> graphql.DocumentNode:
+        return gql.gql(
+            """
+            query getIssues($query: String!, $limit: Int!) {
+                search(query: $query, type: ISSUE, first: $limit) {
+                    nodes {
+                        ... on Issue {
+                            id
+                            url
+                            title
+                            body
+                            createdAt
+                            author {
+                                login
+                            }
                         }
                     }
                 }
             }
-        }
-        """
-    )
+            """
+        )
 
     @property
     def params(self) -> dict[str, typing.Any]:
@@ -170,33 +177,35 @@ def to_dataclass(self) -> list[github_models.Issue]:
         ]
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class GetRepositoryPRsRequest(BaseRequest):
     owner: str
     repository: str
     created_after: datetime.datetime
     limit: int = 100
 
-    document: graphql.DocumentNode = gql.gql(
-        """
-        query getPRs($query: String!, $limit: Int!) {
-            search(query: $query, type: ISSUE, first: $limit) {
-                nodes {
-                    ... on PullRequest {
-                        id
-                        url
-                        title
-                        body
-                        createdAt
-                        author {
-                            login
+    @property
+    def document(self) -> graphql.DocumentNode:
+        return gql.gql(
+            """
+            query getPRs($query: String!, $limit: Int!) {
+                search(query: $query, type: ISSUE, first: $limit) {
+                    nodes {
+                        ... on PullRequest {
+                            id
+                            url
+                            title
+                            body
+                            createdAt
+                            author {
+                                login
+                            }
                         }
                     }
                 }
             }
-        }
-        """
-    )
+            """
+        )
 
     @property
     def params(self) -> dict[str, typing.Any]:
@@ -243,15 +252,16 @@ def to_dataclass(self) -> list[github_models.PullRequest]:
         ]
 
 
+@dataclasses.dataclass(frozen=True)
 class GqlGithubClient:
-    def __init__(self, token: str) -> None:
-        self._token = token
+    token: str
 
     @contextlib.asynccontextmanager
-    async def gql_client(self) -> typing.AsyncGenerator[gql.Client, None]:
+    async def _gql_client(self) -> typing.AsyncGenerator[gql.Client, None]:
         gql_transport = gql_aiohttp.AIOHTTPTransport(
             url="https://api.github.com/graphql",
-            headers={"Authorization": f"Bearer {self._token}"},
+            headers={"Authorization": f"Bearer {self.token}"},
+            ssl=True,
         )
         gql_client = gql.Client(
             transport=gql_transport,
@@ -268,7 +278,7 @@ async def _request[ResponseT: BaseResponse](
         response_model: type[ResponseT],
     ) -> ResponseT:
         logger.debug("Requesting document(%s) params(%s)", request.document, request.params)
-        async with self.gql_client() as gql_client:
+        async with self._gql_client() as gql_client:
             response = await gql_client.execute_async(
                 document=request.document,
                 variable_values=request.params,
@@ -277,19 +287,32 @@ async def _request[ResponseT: BaseResponse](
 
         return parsed_response
 
+    async def _get_repositories(
+        self,
+        request: GetRepositoriesRequest,
+    ) -> GetRepositoriesResponse:
+        return await self._request(request, GetRepositoriesResponse)
+
     async def get_repositories(
         self,
         request: GetRepositoriesRequest,
-    ) -> list[github_models.Repository]:
-        result: list[github_models.Repository] = []
+    ) -> typing.AsyncGenerator[github_models.Repository, None]:
+        after = request.after
         while True:
-            response = await self._request(request, GetRepositoriesResponse)
-            result.extend(response.to_dataclass())
+            response = await self._get_repositories(
+                request=GetRepositoriesRequest(
+                    owner=request.owner,
+                    limit=request.limit,
+                    after=after,
+                ),
+            )
+            for repository in response.to_dataclass():
+                yield repository
             if not response.search.page_info.has_next_page:
                 break
-            request.after = response.search.page_info.end_cursor
 
-        return result
+            after = response.search.page_info.end_cursor
+            assert after is not None
 
     async def get_repository_issues(
         self,
diff --git a/backend/lib/github/clients/rest.py b/backend/lib/github/clients/rest.py
index 43a9847..45fa0c9 100644
--- a/backend/lib/github/clients/rest.py
+++ b/backend/lib/github/clients/rest.py
@@ -5,34 +5,33 @@
 import typing
 
 import aiohttp
-import pydantic
 
 import lib.github.models as github_models
+import lib.utils.pydantic as pydantic_utils
 
 logger = logging.getLogger(__name__)
 
 
 class BaseRequest(abc.ABC):
-    method: str
+    @property
+    @abc.abstractmethod
+    def method(self) -> str: ...
 
     @property
     @abc.abstractmethod
     def url(self) -> str: ...
 
     @property
-    def params(self) -> dict[str, typing.Any]:
-        return {}
-
-
-class BaseModel(pydantic.BaseModel): ...
+    @abc.abstractmethod
+    def params(self) -> dict[str, typing.Any]: ...
 
 
-class BaseResponse(BaseModel):
+class BaseResponse(pydantic_utils.BaseModel):
     def to_dataclass(self) -> typing.Any:
         raise NotImplementedError
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class GetRepositoryWorkflowRunsRequest(BaseRequest):
     owner: str
     repository: str
@@ -40,7 +39,10 @@ class GetRepositoryWorkflowRunsRequest(BaseRequest):
     per_page: int = 100
     page: int = 1
     exclude_pull_requests: bool = True
-    method: str = "GET"
+
+    @property
+    def method(self) -> str:
+        return "GET"
 
     @property
     def url(self) -> str:
@@ -57,7 +59,7 @@ def params(self) -> dict[str, typing.Any]:
 
 
 class GetRepositoryWorkflowRunsResponse(BaseResponse):
-    class WorkflowRun(pydantic.BaseModel):
+    class WorkflowRun(pydantic_utils.BaseModel):
         id: int
         name: str
         html_url: str
@@ -82,14 +84,10 @@ def to_dataclass(self) -> list[github_models.WorkflowRun]:
         ]
 
 
+@dataclasses.dataclass(frozen=True)
 class RestGithubClient:
-    def __init__(
-        self,
-        aiohttp_client: aiohttp.ClientSession,
-        token: str,
-    ) -> None:
-        self._aiohttp_client = aiohttp_client
-        self._token = token
+    aiohttp_client: aiohttp.ClientSession
+    token: str
 
     @classmethod
     def from_token(cls, token: str) -> typing.Self:
@@ -97,7 +95,7 @@ def from_token(cls, token: str) -> typing.Self:
         return cls(aiohttp_client=aiohttp_client, token=token)
 
     async def dispose(self) -> None:
-        await self._aiohttp_client.close()
+        await self.aiohttp_client.close()
 
     async def _request[ResponseT: BaseResponse](
         self,
@@ -105,11 +103,11 @@ async def _request[ResponseT: BaseResponse](
         response_model: type[ResponseT],
     ) -> ResponseT:
         headers = {
-            "Authorization": f"Bearer {self._token}",
+            "Authorization": f"Bearer {self.token}",
             "Accept": "application/vnd.github.v3+json",
         }
         logger.debug("Requesting method(%s) url(%s) params(%s)", request.method, request.url, request.params)
-        async with self._aiohttp_client.request(
+        async with self.aiohttp_client.request(
             method=request.method,
             url=request.url,
             params=request.params,
@@ -119,19 +117,35 @@ async def _request[ResponseT: BaseResponse](
             data = await response.json()
             return response_model.model_validate(data)
 
+    async def _get_repository_workflow_runs(
+        self,
+        request: GetRepositoryWorkflowRunsRequest,
+    ) -> GetRepositoryWorkflowRunsResponse:
+        return await self._request(request, GetRepositoryWorkflowRunsResponse)
+
     async def get_repository_workflow_runs(
         self,
         request: GetRepositoryWorkflowRunsRequest,
     ) -> typing.AsyncGenerator[github_models.WorkflowRun, None]:
+        page = request.page
+
         while True:
-            response = await self._request(request, GetRepositoryWorkflowRunsResponse)
+            response = await self._get_repository_workflow_runs(
+                request=GetRepositoryWorkflowRunsRequest(
+                    owner=request.owner,
+                    repository=request.repository,
+                    created_after=request.created_after,
+                    page=page,
+                    per_page=request.per_page,
+                ),
+            )
             if not response.workflow_runs:
                 return
 
             for workflow_run in response.to_dataclass():
                 yield workflow_run
 
-            request.page += 1
+            page += 1
 
 
 __all__ = [
diff --git a/backend/lib/github/models.py b/backend/lib/github/models.py
index 6b8e436..5c913c8 100644
--- a/backend/lib/github/models.py
+++ b/backend/lib/github/models.py
@@ -2,13 +2,13 @@
 import datetime
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class Repository:
     owner: str
     name: str
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class Issue:
     id: str
     author: str | None
@@ -18,7 +18,7 @@ class Issue:
     created_at: datetime.datetime
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class PullRequest:
     id: str
     author: str | None
diff --git a/backend/lib/github/triggers.py b/backend/lib/github/triggers.py
index 600427c..56ecec3 100644
--- a/backend/lib/github/triggers.py
+++ b/backend/lib/github/triggers.py
@@ -1,4 +1,5 @@
 import contextlib
+import dataclasses
 import datetime
 import logging
 import re
@@ -219,18 +220,12 @@ class GithubTriggerState(pydantic_utils.BaseModel):
     )
 
 
+@dataclasses.dataclass(frozen=True)
 class GithubTriggerProcessor(task_base.TriggerProcessor[GithubTriggerConfig]):
-    def __init__(
-        self,
-        raw_state: lib.task.protocols.StateProtocol,
-        gql_github_client: github_clients.GqlGithubClient,
-        rest_github_client: github_clients.RestGithubClient,
-        config: GithubTriggerConfig,
-    ) -> None:
-        self._raw_state = raw_state
-        self._gql_github_client = gql_github_client
-        self._rest_github_client = rest_github_client
-        self._config = config
+    config: GithubTriggerConfig
+    raw_state: lib.task.protocols.StateProtocol
+    gql_github_client: github_clients.GqlGithubClient
+    rest_github_client: github_clients.RestGithubClient
 
     @classmethod
     def from_config(
@@ -249,11 +244,11 @@ def from_config(
         )
 
     async def dispose(self) -> None:
-        await self._rest_github_client.dispose()
+        await self.rest_github_client.dispose()
 
     @contextlib.asynccontextmanager
     async def _acquire_state(self) -> typing.AsyncIterator[GithubTriggerState]:
-        async with self._raw_state.acquire() as raw_state:
+        async with self.raw_state.acquire() as raw_state:
             if raw_state is None:
                 raw_state = {}
 
@@ -261,15 +256,18 @@ async def _acquire_state(self) -> typing.AsyncIterator[GithubTriggerState]:
             try:
                 yield state
             finally:
-                await self._raw_state.set(state.model_dump(mode="json"))
+                await self.raw_state.set(state.model_dump(mode="json"))
 
     async def produce_events(self) -> typing.AsyncGenerator[task_base.Event, None]:
-        repositories = await self._gql_github_client.get_repositories(
+        repositories: list[github_models.Repository] = []
+
+        async for repository in self.gql_github_client.get_repositories(
             github_clients.GetRepositoriesRequest(
-                owner=self._config.owner,
+                owner=self.config.owner,
             )
-        )
-        repositories = [repository for repository in repositories if self._config.is_repository_applicable(repository)]
+        ):
+            if self.config.is_repository_applicable(repository):
+                repositories.append(repository)
 
         async with self._acquire_state() as state:
             async for event in asyncio_utils.GatherIterators(
@@ -278,7 +276,7 @@ async def produce_events(self) -> typing.AsyncGenerator[task_base.Event, None]:
                     state=state,
                     repositories=repositories,
                 )
-                for subtrigger in self._config.subtriggers
+                for subtrigger in self.config.subtriggers
             ):
                 yield event
 
@@ -333,15 +331,15 @@ async def _process_repository_issue_created(
     ) -> typing.AsyncGenerator[task_base.Event, None]:
         if repository not in state.repository_issue_created:
             state.repository_issue_created[repository] = RepositoryIssueCreatedState.default_factory(
-                self._config.default_timedelta,
+                self.config.default_timedelta,
             )
         repository_state = state.repository_issue_created[repository]
         last_issue_created = repository_state.last_issue_created
 
         while True:
-            issues = await self._gql_github_client.get_repository_issues(
+            issues = await self.gql_github_client.get_repository_issues(
                 github_clients.GetRepositoryIssuesRequest(
-                    owner=self._config.owner,
+                    owner=self.config.owner,
                     repository=repository,
                     created_after=last_issue_created,
                 )
@@ -353,7 +351,7 @@ async def _process_repository_issue_created(
                 if subtrigger.is_applicable(issue):
                     yield task_base.Event(
                         id=f"issue_created__{issue.id}",
-                        title=f"📋New issue in {self._config.owner}/{repository}",
+                        title=f"📋New issue in {self.config.owner}/{repository}",
                         body=f"Issue created by {issue.author}: {issue.title}",
                         url=issue.url,
                     )
@@ -384,15 +382,15 @@ async def _process_repository_pr_created(
     ) -> typing.AsyncGenerator[task_base.Event, None]:
         if repository not in state.repository_pr_created:
             state.repository_pr_created[repository] = RepositoryPRCreatedState.default_factory(
-                self._config.default_timedelta,
+                self.config.default_timedelta,
             )
         repository_state = state.repository_pr_created[repository]
         last_pr_created = repository_state.last_pr_created
 
         while True:
-            prs = await self._gql_github_client.get_repository_pull_requests(
+            prs = await self.gql_github_client.get_repository_pull_requests(
                 github_clients.GetRepositoryPRsRequest(
-                    owner=self._config.owner,
+                    owner=self.config.owner,
                     repository=repository,
                     created_after=last_pr_created,
                 )
@@ -404,7 +402,7 @@ async def _process_repository_pr_created(
                 if subtrigger.is_applicable(pr):
                     yield task_base.Event(
                         id=f"pr_created__{pr.id}",
-                        title=f"🛠New PR in {self._config.owner}/{repository}",
+                        title=f"🛠New PR in {self.config.owner}/{repository}",
                         body=f"PR created by {pr.author}: {pr.title}",
                         url=pr.url,
                     )
@@ -435,27 +433,27 @@ async def _process_repository_failed_workflow_run(
     ) -> typing.AsyncGenerator[task_base.Event, None]:
         if repository not in state.repository_failed_workflow_run:
             state.repository_failed_workflow_run[repository] = RepositoryFailedWorkflowRunState.default_factory(
-                self._config.default_timedelta,
+                self.config.default_timedelta,
             )
         repository_state = state.repository_failed_workflow_run[repository]
 
-        request = github_clients.GetRepositoryWorkflowRunsRequest(
-            owner=self._config.owner,
-            repository=repository,
-            created_after=repository_state.oldest_incomplete_created,
-        )
-
         oldest_incomplete_created = None
         last_created = None
 
-        async for workflow_run in self._rest_github_client.get_repository_workflow_runs(request):
+        async for workflow_run in self.rest_github_client.get_repository_workflow_runs(
+            request=github_clients.GetRepositoryWorkflowRunsRequest(
+                owner=self.config.owner,
+                repository=repository,
+                created_after=repository_state.oldest_incomplete_created,
+            ),
+        ):
             if (
                 subtrigger.is_applicable(workflow_run)
                 and workflow_run not in repository_state.already_reported_failed_runs
             ):
                 yield task_base.Event(
-                    id=f"failed_workflow_run__{self._config.owner}__{repository}__{workflow_run.id}",
-                    title=f"🔥Failed workflow run in {self._config.owner}/{repository}",
+                    id=f"failed_workflow_run__{self.config.owner}__{repository}__{workflow_run.id}",
+                    title=f"🔥Failed workflow run in {self.config.owner}/{repository}",
                     body=f"Workflow run {workflow_run.name} failed",
                     url=workflow_run.url,
                 )
diff --git a/backend/lib/task/base/action.py b/backend/lib/task/base/action.py
index d95e072..d729c78 100644
--- a/backend/lib/task/base/action.py
+++ b/backend/lib/task/base/action.py
@@ -32,7 +32,7 @@ async def dispose(self) -> None: ...
     async def process(self, event: task_configs_event.Event) -> None: ...
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class RegistryRecord[ConfigT: BaseActionConfig]:
     config_class: type[ConfigT]
     processor_class: type[ActionProcessor[ConfigT]]
diff --git a/backend/lib/task/base/task.py b/backend/lib/task/base/task.py
index b4a6034..8b3af70 100644
--- a/backend/lib/task/base/task.py
+++ b/backend/lib/task/base/task.py
@@ -37,7 +37,7 @@ def is_ready(self, last_run: datetime.datetime | None) -> bool:
         return schedule.next() <= datetime.datetime.now(tz=last_run.tzinfo)
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class RegistryRecord[ConfigT: BaseTaskConfig]:
     config_class: type[ConfigT]
 
diff --git a/backend/lib/task/base/trigger.py b/backend/lib/task/base/trigger.py
index d6f71c0..8a374b2 100644
--- a/backend/lib/task/base/trigger.py
+++ b/backend/lib/task/base/trigger.py
@@ -33,7 +33,7 @@ def produce_events(self) -> typing.AsyncGenerator[task_base.Event, None]: ...
     async def dispose(self) -> None: ...
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class RegistryRecord[ConfigT: BaseTriggerConfig]:
     config_class: type[ConfigT]
     processor_class: type[TriggerProcessor[ConfigT]]
diff --git a/backend/lib/task/repositories/config/base.py b/backend/lib/task/repositories/config/base.py
index 20d1700..8366788 100644
--- a/backend/lib/task/repositories/config/base.py
+++ b/backend/lib/task/repositories/config/base.py
@@ -29,7 +29,7 @@ async def dispose(self) -> None: ...
     async def get_config(self) -> task_base.RootConfig: ...
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class RegistryRecord[SettingsT: BaseConfigSettings]:
     settings_class: type[SettingsT]
     repository_class: type[BaseConfigRepository[SettingsT]]
diff --git a/backend/lib/task/repositories/queue/base.py b/backend/lib/task/repositories/queue/base.py
index 63e5b23..429b70e 100644
--- a/backend/lib/task/repositories/queue/base.py
+++ b/backend/lib/task/repositories/queue/base.py
@@ -100,7 +100,7 @@ async def consume(self, topic: JobTopic, item: QueueItem) -> None: ...
     async def close_topic(self, topic: JobTopic) -> None: ...
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class RegistryRecord[SettingsT: BaseQueueSettings]:
     settings_class: type[SettingsT]
     repository_class: type[BaseQueueRepository[SettingsT]]
diff --git a/backend/lib/task/repositories/state/base.py b/backend/lib/task/repositories/state/base.py
index f07d394..e99e8f2 100644
--- a/backend/lib/task/repositories/state/base.py
+++ b/backend/lib/task/repositories/state/base.py
@@ -55,7 +55,7 @@ async def get_state(self, path: str) -> task_protocols.StateProtocol:
         return State(repository=self, path=path)
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class RegistryRecord[SettingsT: BaseStateSettings]:
     settings_class: type[SettingsT]
     repository_class: type[BaseStateRepository[SettingsT]]
diff --git a/backend/lib/telegram/actions.py b/backend/lib/telegram/actions.py
index e713592..16a21cd 100644
--- a/backend/lib/telegram/actions.py
+++ b/backend/lib/telegram/actions.py
@@ -1,9 +1,11 @@
+import dataclasses
 import logging
 import typing
 
 import aiohttp
 
 import lib.task.base as task_base
+import lib.telegram.clients as telegram_clients
 import lib.utils.pydantic as pydantic_utils
 
 logger = logging.getLogger(__name__)
@@ -20,17 +22,14 @@ class TelegramWebhookActionConfig(task_base.BaseActionConfig):
     max_message_body_length: int = 500
 
 
+@dataclasses.dataclass(frozen=True)
 class TelegramWebhookProcessor(task_base.ActionProcessor[TelegramWebhookActionConfig]):
-    def __init__(
-        self,
-        config: TelegramWebhookActionConfig,
-        aiohttp_client: aiohttp.ClientSession,
-    ):
-        self._config = config
-        self._aiohttp_client = aiohttp_client
+    config: TelegramWebhookActionConfig
+    aiohttp_client: aiohttp.ClientSession
+    telegram_client: telegram_clients.RestTelegramClient
 
     async def dispose(self) -> None:
-        await self._aiohttp_client.close()
+        await self.aiohttp_client.close()
 
     @classmethod
     def from_config(
@@ -38,25 +37,32 @@ def from_config(
         config: TelegramWebhookActionConfig,
     ) -> typing.Self:
         aiohttp_client = aiohttp.ClientSession()
+        telegram_client = telegram_clients.RestTelegramClient(
+            token=config.token_secret.value,
+            aiohttp_client=aiohttp_client,
+        )
 
         return cls(
             config=config,
             aiohttp_client=aiohttp_client,
+            telegram_client=telegram_client,
+        )
+
+    def _format_message(self, event: task_base.Event) -> str:
+        return (
+            f"<b>{trim_string(event.title, self.config.max_message_title_length)}</b>"
+            f"\n{trim_string(event.body, self.config.max_message_body_length)}"
+            f"\n{event.url}"
         )
 
     async def process(self, event: task_base.Event) -> None:
-        async with self._aiohttp_client.post(
-            f"https://api.telegram.org/bot{self._config.token_secret.value}/sendMessage",
-            params={
-                "chat_id": self._config.chat_id_secret.value,
-                "text": f"<b>{trim_string(event.title, self._config.max_message_title_length)}</b>"
-                f"\n{trim_string(event.body, self._config.max_message_body_length)}"
-                f"\n{event.url}",
-                "parse_mode": "HTML",
-                "disable_web_page_preview": "true",
-            },
-        ) as response:
-            response.raise_for_status()
+        text = self._format_message(event)
+        await self.telegram_client.send_message(
+            request=telegram_clients.SendMessageRequest(
+                chat_id=self.config.chat_id_secret.value,
+                text=text,
+            ),
+        )
 
 
 def register_default_plugins() -> None:
diff --git a/backend/lib/telegram/clients.py b/backend/lib/telegram/clients.py
new file mode 100644
index 0000000..2b4629e
--- /dev/null
+++ b/backend/lib/telegram/clients.py
@@ -0,0 +1,52 @@
+import dataclasses
+
+import aiohttp
+import aiohttp.typedefs as aiohttp_typedefs
+
+
+@dataclasses.dataclass(frozen=True)
+class SendMessageRequest:
+    chat_id: str
+    text: str
+    parse_mode: str = "HTML"
+    disable_web_page_preview: bool = True
+
+    @property
+    def method(self) -> str:
+        return "POST"
+
+    @property
+    def path(self) -> str:
+        return "/sendMessage"
+
+    @property
+    def params(self) -> aiohttp_typedefs.Query:
+        return {
+            "chat_id": self.chat_id,
+            "text": self.text,
+            "parse_mode": self.parse_mode,
+            "disable_web_page_preview": "true" if self.disable_web_page_preview else "false",
+        }
+
+
+@dataclasses.dataclass(frozen=True)
+class RestTelegramClient:
+    aiohttp_client: aiohttp.ClientSession
+    token: str
+
+    def _prepare_url(self, path: str) -> str:
+        return f"https://api.telegram.org/bot{self.token}{path}"
+
+    async def send_message(self, request: SendMessageRequest) -> None:
+        async with self.aiohttp_client.request(
+            method=request.method,
+            url=self._prepare_url(request.path),
+            params=request.params,
+        ) as response:
+            response.raise_for_status()
+
+
+__all__ = [
+    "RestTelegramClient",
+    "SendMessageRequest",
+]
diff --git a/backend/lib/utils/aiojobs/scheduler.py b/backend/lib/utils/aiojobs/scheduler.py
index c413d9f..1402ace 100644
--- a/backend/lib/utils/aiojobs/scheduler.py
+++ b/backend/lib/utils/aiojobs/scheduler.py
@@ -12,7 +12,7 @@
 AioJobsScheduler = aiojobs.Scheduler
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class Settings:
     limit: int | None
     pending_limit: int | None
diff --git a/backend/lib/utils/lifecycle.py b/backend/lib/utils/lifecycle.py
index 89723aa..00770fc 100644
--- a/backend/lib/utils/lifecycle.py
+++ b/backend/lib/utils/lifecycle.py
@@ -7,7 +7,7 @@
 Task = asyncio.Task[typing.Any]
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class Callback:
     awaitable: Awaitable
     error_message: str
diff --git a/backend/lib/utils/logging/config.py b/backend/lib/utils/logging/config.py
index 7a47dff..5b13e03 100644
--- a/backend/lib/utils/logging/config.py
+++ b/backend/lib/utils/logging/config.py
@@ -14,7 +14,7 @@ def initialize(
     logging_config.dictConfig(config)
 
 
-@dataclasses.dataclass
+@dataclasses.dataclass(frozen=True)
 class LoggerConfig:
     propagate: bool
     level: LogLevel
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
new file mode 100644
index 0000000..078f8a4
--- /dev/null
+++ b/backend/tests/conftest.py
@@ -0,0 +1,8 @@
+import pytest
+
+import tests.settings as test_settings
+
+
+@pytest.fixture(name="settings")
+def settings_fixture() -> test_settings.Settings:
+    return test_settings.Settings()
diff --git a/backend/tests/integration/github/__init__.py b/backend/tests/integration/github/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/backend/tests/integration/github/clients/__init__.py b/backend/tests/integration/github/clients/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/backend/tests/integration/github/clients/gql/__init__.py b/backend/tests/integration/github/clients/gql/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/backend/tests/integration/github/clients/gql/conftest.py b/backend/tests/integration/github/clients/gql/conftest.py
new file mode 100644
index 0000000..75429df
--- /dev/null
+++ b/backend/tests/integration/github/clients/gql/conftest.py
@@ -0,0 +1,9 @@
+import pytest
+
+import lib.github.clients as github_clients
+import tests.settings as test_settings
+
+
+@pytest.fixture(name="github_gql_client")
+def github_gql_client_fixture(settings: test_settings.Settings) -> github_clients.GqlGithubClient:
+    return github_clients.GqlGithubClient(token=settings.github_token)
diff --git a/backend/tests/integration/github/clients/gql/test_get_repositories.py b/backend/tests/integration/github/clients/gql/test_get_repositories.py
new file mode 100644
index 0000000..90ba582
--- /dev/null
+++ b/backend/tests/integration/github/clients/gql/test_get_repositories.py
@@ -0,0 +1,48 @@
+import pytest
+
+import lib.github.clients as github_clients
+import lib.github.models as github_models
+
+
+@pytest.mark.asyncio
+async def test_default(github_gql_client: github_clients.GqlGithubClient):
+    iterator = github_gql_client.get_repositories(
+        request=github_clients.GetRepositoriesRequest(
+            owner="python",
+        ),
+    )
+
+    assert await anext(iterator) == github_models.Repository(
+        name="cpython",
+        owner="python",
+    )
+
+
+@pytest.mark.asyncio
+async def test_multiple_requests(github_gql_client: github_clients.GqlGithubClient):
+    iterator = github_gql_client.get_repositories(
+        request=github_clients.GetRepositoriesRequest(
+            owner="python",
+            limit=1,
+        ),
+    )
+
+    assert await anext(iterator) == github_models.Repository(
+        name="cpython",
+        owner="python",
+    )
+    assert await anext(iterator) == github_models.Repository(
+        name="mypy",
+        owner="python",
+    )
+
+
+@pytest.mark.asyncio
+async def test_finite(github_gql_client: github_clients.GqlGithubClient):
+    iterator = github_gql_client.get_repositories(
+        request=github_clients.GetRepositoriesRequest(
+            owner="definetly-not-a-real-org",
+        ),
+    )
+
+    assert len([item async for item in iterator]) == 0
diff --git a/backend/tests/integration/github/clients/gql/test_get_repository_issues.py b/backend/tests/integration/github/clients/gql/test_get_repository_issues.py
new file mode 100644
index 0000000..3b0f166
--- /dev/null
+++ b/backend/tests/integration/github/clients/gql/test_get_repository_issues.py
@@ -0,0 +1,26 @@
+import datetime
+
+import pytest
+
+import lib.github.clients as github_clients
+
+
+@pytest.mark.asyncio
+async def test_default(github_gql_client: github_clients.GqlGithubClient):
+    """Test getting issues from a repository with default parameters."""
+    issues = await github_gql_client.get_repository_issues(
+        request=github_clients.GetRepositoryIssuesRequest(
+            owner="python",
+            repository="cpython",
+            created_after=datetime.datetime(2025, 1, 1),
+            limit=1,
+        ),
+    )
+
+    assert len(issues) == 1
+    issue = issues[0]
+    assert issue.id == "I_kwDOBN0Z8c6kzGKa"
+    assert issue.author == "paulie4"
+    assert issue.url == "https://github.com/python/cpython/issues/128388"
+    assert issue.title == "`pyrepl` on Windows: add Ctrl+← and Ctrl+→ word-skipping and other keybindings"
+    assert issue.created_at == datetime.datetime(2025, 1, 1, 5, 33, 57, tzinfo=datetime.UTC)
diff --git a/backend/tests/integration/github/clients/gql/test_get_repository_pull_requests.py b/backend/tests/integration/github/clients/gql/test_get_repository_pull_requests.py
new file mode 100644
index 0000000..d0c3db2
--- /dev/null
+++ b/backend/tests/integration/github/clients/gql/test_get_repository_pull_requests.py
@@ -0,0 +1,25 @@
+import datetime
+
+import pytest
+
+import lib.github.clients as github_clients
+
+
+@pytest.mark.asyncio
+async def test__default(github_gql_client: github_clients.GqlGithubClient):
+    pull_requests = await github_gql_client.get_repository_pull_requests(
+        request=github_clients.GetRepositoryPRsRequest(
+            owner="python",
+            repository="cpython",
+            created_after=datetime.datetime(2025, 1, 1),
+            limit=1,
+        ),
+    )
+
+    assert len(pull_requests) == 1
+    pull_request = pull_requests[0]
+    assert pull_request.id == "PR_kwDOBN0Z8c6GhTCQ"
+    assert pull_request.author == "paulie4"
+    assert pull_request.url == "https://github.com/python/cpython/pull/128389"
+    assert pull_request.title == "gh-128388: pyrepl on Windows: add meta and ctrl+arrow keybindings"
+    assert pull_request.created_at == datetime.datetime(2025, 1, 1, 5, 54, 29, tzinfo=datetime.UTC)
diff --git a/backend/tests/integration/github/clients/rest/__init__.py b/backend/tests/integration/github/clients/rest/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/backend/tests/integration/github/clients/rest/conftest.py b/backend/tests/integration/github/clients/rest/conftest.py
new file mode 100644
index 0000000..f2902b9
--- /dev/null
+++ b/backend/tests/integration/github/clients/rest/conftest.py
@@ -0,0 +1,17 @@
+import typing
+
+import pytest_asyncio
+
+import lib.github.clients as github_clients
+import tests.settings as test_settings
+
+
+@pytest_asyncio.fixture(name="github_rest_client")
+async def github_rest_client_fixture(
+    settings: test_settings.Settings,
+) -> typing.AsyncGenerator[github_clients.RestGithubClient, None]:
+    client = github_clients.RestGithubClient.from_token(settings.github_token)
+    try:
+        yield client
+    finally:
+        await client.dispose()
diff --git a/backend/tests/integration/github/clients/rest/test_get_repository_workflow_runs.py b/backend/tests/integration/github/clients/rest/test_get_repository_workflow_runs.py
new file mode 100644
index 0000000..43ad9ed
--- /dev/null
+++ b/backend/tests/integration/github/clients/rest/test_get_repository_workflow_runs.py
@@ -0,0 +1,48 @@
+import datetime
+
+import pytest
+
+import lib.github.clients as github_clients
+import lib.github.models as github_models
+
+
+@pytest.mark.asyncio
+async def test_default(github_rest_client: github_clients.RestGithubClient):
+    iterator = github_rest_client.get_repository_workflow_runs(
+        request=github_clients.GetRepositoryWorkflowRunsRequest(
+            owner="ovsds",
+            repository="github-watcher",
+            created_after=datetime.datetime(2025, 1, 1),
+        ),
+    )
+
+    workflow_run = await anext(iterator)
+    assert isinstance(workflow_run, github_models.WorkflowRun)
+
+
+@pytest.mark.asyncio
+async def test_per_page(github_rest_client: github_clients.RestGithubClient):
+    iterator = github_rest_client.get_repository_workflow_runs(
+        request=github_clients.GetRepositoryWorkflowRunsRequest(
+            owner="ovsds",
+            repository="github-watcher",
+            created_after=datetime.datetime(2025, 1, 1),
+            per_page=1,
+        ),
+    )
+
+    for _ in range(2):
+        workflow_run = await anext(iterator)
+        assert isinstance(workflow_run, github_models.WorkflowRun)
+
+
+@pytest.mark.asyncio
+async def test_finite(github_rest_client: github_clients.RestGithubClient):
+    iterator = github_rest_client.get_repository_workflow_runs(
+        request=github_clients.GetRepositoryWorkflowRunsRequest(
+            owner="ovsds",
+            repository="github-watcher",
+            created_after=datetime.datetime(3025, 1, 1),
+        ),
+    )
+    assert len([item async for item in iterator]) == 0
diff --git a/backend/tests/integration/telegram/__init__.py b/backend/tests/integration/telegram/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/backend/tests/integration/telegram/clients/__init__.py b/backend/tests/integration/telegram/clients/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/backend/tests/integration/telegram/clients/rest/__init__.py b/backend/tests/integration/telegram/clients/rest/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/backend/tests/integration/telegram/clients/rest/conftest.py b/backend/tests/integration/telegram/clients/rest/conftest.py
new file mode 100644
index 0000000..ffc97d1
--- /dev/null
+++ b/backend/tests/integration/telegram/clients/rest/conftest.py
@@ -0,0 +1,27 @@
+import typing
+
+import aiohttp
+import pytest_asyncio
+
+import lib.telegram.clients as telegram_clients
+import tests.settings as test_settings
+
+
+@pytest_asyncio.fixture(name="aiohttp_client")
+async def aiohttp_client_fixture() -> typing.AsyncGenerator[aiohttp.ClientSession, None]:
+    client = aiohttp.ClientSession()
+    try:
+        yield client
+    finally:
+        await client.close()
+
+
+@pytest_asyncio.fixture(name="telegram_client")
+async def telegram_client_fixture(
+    aiohttp_client: aiohttp.ClientSession,
+    settings: test_settings.Settings,
+) -> telegram_clients.RestTelegramClient:
+    return telegram_clients.RestTelegramClient(
+        token=settings.telegram_token,
+        aiohttp_client=aiohttp_client,
+    )
diff --git a/backend/tests/integration/telegram/clients/rest/test_send_message.py b/backend/tests/integration/telegram/clients/rest/test_send_message.py
new file mode 100644
index 0000000..91c1802
--- /dev/null
+++ b/backend/tests/integration/telegram/clients/rest/test_send_message.py
@@ -0,0 +1,17 @@
+import pytest
+
+import lib.telegram.clients as telegram_clients
+import tests.settings as test_settings
+
+
+@pytest.mark.asyncio
+async def test_default(
+    telegram_client: telegram_clients.RestTelegramClient,
+    settings: test_settings.Settings,
+):
+    await telegram_client.send_message(
+        request=telegram_clients.SendMessageRequest(
+            chat_id=settings.telegram_chat_id,
+            text="Integration test",
+        ),
+    )
diff --git a/backend/tests/settings.py b/backend/tests/settings.py
new file mode 100644
index 0000000..e9868b2
--- /dev/null
+++ b/backend/tests/settings.py
@@ -0,0 +1,13 @@
+import lib.utils.pydantic as pydantic_utils
+
+
+class Settings(pydantic_utils.BaseSettings):
+    github_token: str = NotImplemented
+
+    telegram_token: str = NotImplemented
+    telegram_chat_id: str = NotImplemented
+
+
+__all__ = [
+    "Settings",
+]