diff --git a/changelog/1057.trivial b/changelog/1057.trivial
new file mode 100644
index 00000000..df1b3c04
--- /dev/null
+++ b/changelog/1057.trivial
@@ -0,0 +1 @@
+The internals of pytest-xdist are now fully typed. The typing is not exposed yet.
diff --git a/pyproject.toml b/pyproject.toml
index 71d429db..d84a6f88 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -137,19 +137,8 @@ lines-after-imports = 2
 [tool.mypy]
 mypy_path = ["src"]
 files = ["src", "testing"]
-# TODO: Enable this & fix errors.
-# check_untyped_defs = true
-disallow_any_generics = true
-ignore_missing_imports = true
-no_implicit_optional = true
-show_error_codes = true
-strict_equality = true
-warn_redundant_casts = true
-warn_return_any = true
+strict = true
 warn_unreachable = true
-warn_unused_configs = true
-# TODO: Enable this & fix errors.
-# no_implicit_reexport = true
 
 
 [tool.towncrier]
diff --git a/src/xdist/dsession.py b/src/xdist/dsession.py
index 9671b2fd..c3a04399 100644
--- a/src/xdist/dsession.py
+++ b/src/xdist/dsession.py
@@ -5,11 +5,15 @@
 from queue import Empty
 from queue import Queue
 import sys
+from typing import Any
 from typing import Sequence
+import warnings
 
+import execnet
 import pytest
 
 from xdist.remote import Producer
+from xdist.remote import WorkerInfo
 from xdist.scheduler import EachScheduling
 from xdist.scheduler import LoadFileScheduling
 from xdist.scheduler import LoadGroupScheduling
@@ -18,6 +22,7 @@
 from xdist.scheduler import Scheduling
 from xdist.scheduler import WorkStealingScheduling
 from xdist.workermanage import NodeManager
+from xdist.workermanage import WorkerController
 
 
 class Interrupted(KeyboardInterrupt):
@@ -38,29 +43,31 @@ class DSession:
     it will wait for instructions.
     """
 
-    def __init__(self, config):
+    shouldstop: bool | str
+
+    def __init__(self, config: pytest.Config) -> None:
         self.config = config
         self.log = Producer("dsession", enabled=config.option.debug)
-        self.nodemanager = None
-        self.sched = None
+        self.nodemanager: NodeManager | None = None
+        self.sched: Scheduling | None = None
         self.shuttingdown = False
         self.countfailures = 0
-        self.maxfail = config.getvalue("maxfail")
-        self.queue = Queue()
-        self._session = None
-        self._failed_collection_errors = {}
-        self._active_nodes = set()
+        self.maxfail: int = config.getvalue("maxfail")
+        self.queue: Queue[tuple[str, dict[str, Any]]] = Queue()
+        self._session: pytest.Session | None = None
+        self._failed_collection_errors: dict[object, bool] = {}
+        self._active_nodes: set[WorkerController] = set()
         self._failed_nodes_count = 0
         self._max_worker_restart = get_default_max_worker_restart(self.config)
         # summary message to print at the end of the session
-        self._summary_report = None
+        self._summary_report: str | None = None
         self.terminal = config.pluginmanager.getplugin("terminalreporter")
         if self.terminal:
             self.trdist = TerminalDistReporter(config)
             config.pluginmanager.register(self.trdist, "terminaldistreporter")
 
     @property
-    def session_finished(self):
+    def session_finished(self) -> bool:
         """Return True if the distributed session has finished.
 
         This means all nodes have executed all test items.  This is
@@ -68,12 +75,12 @@ def session_finished(self):
         """
         return bool(self.shuttingdown and not self._active_nodes)
 
-    def report_line(self, line):
+    def report_line(self, line: str) -> None:
         if self.terminal and self.config.option.verbose >= 0:
             self.terminal.write_line(line)
 
     @pytest.hookimpl(trylast=True)
-    def pytest_sessionstart(self, session):
+    def pytest_sessionstart(self, session: pytest.Session) -> None:
         """Creates and starts the nodes.
 
         The nodes are setup to put their events onto self.queue.  As
@@ -85,7 +92,7 @@ def pytest_sessionstart(self, session):
         self._session = session
 
     @pytest.hookimpl
-    def pytest_sessionfinish(self, session):
+    def pytest_sessionfinish(self) -> None:
         """Shutdown all nodes."""
         nm = getattr(self, "nodemanager", None)  # if not fully initialized
         if nm is not None:
@@ -93,7 +100,7 @@ def pytest_sessionfinish(self, session):
         self._session = None
 
     @pytest.hookimpl
-    def pytest_collection(self):
+    def pytest_collection(self) -> bool:
         # prohibit collection of test items in controller process
         return True
 
@@ -115,7 +122,7 @@ def pytest_xdist_make_scheduler(self, config, log) -> Scheduling | None:
         return None
 
     @pytest.hookimpl
-    def pytest_runtestloop(self):
+    def pytest_runtestloop(self) -> bool:
         self.sched = self.config.hook.pytest_xdist_make_scheduler(
             config=self.config, log=self.log
         )
@@ -132,7 +139,7 @@ def pytest_runtestloop(self):
             raise pending_exception
         return True
 
-    def loop_once(self):
+    def loop_once(self) -> None:
         """Process one callback from one of the workers."""
         while 1:
             if not self._active_nodes:
@@ -150,6 +157,7 @@ def loop_once(self):
         call = getattr(self, method)
         self.log("calling method", method, kwargs)
         call(**kwargs)
+        assert self.sched is not None
         if self.sched.tests_finished:
             self.triggershutdown()
 
@@ -157,7 +165,11 @@ def loop_once(self):
     # callbacks for processing events from workers
     #
 
-    def worker_workerready(self, node, workerinfo):
+    def worker_workerready(
+        self,
+        node: WorkerController,
+        workerinfo: WorkerInfo,
+    ) -> None:
         """Emitted when a node first starts up.
 
         This adds the node to the scheduler, nodes continue with
@@ -171,9 +183,10 @@ def worker_workerready(self, node, workerinfo):
         if self.shuttingdown:
             node.shutdown()
         else:
+            assert self.sched is not None
             self.sched.add_node(node)
 
-    def worker_workerfinished(self, node):
+    def worker_workerfinished(self, node: WorkerController) -> None:
         """Emitted when node executes its pytest_sessionfinish hook.
 
         Removes the node from the scheduler.
@@ -194,12 +207,15 @@ def worker_workerfinished(self, node):
                     self.shouldstop = shouldx
                 break
         else:
+            assert self.sched is not None
             if node in self.sched.nodes:
                 crashitem = self.sched.remove_node(node)
                 assert not crashitem, (crashitem, node)
         self._active_nodes.remove(node)
 
-    def worker_internal_error(self, node, formatted_error):
+    def worker_internal_error(
+        self, node: WorkerController, formatted_error: str
+    ) -> None:
         """
         pytest_internalerror() was called on the worker.
 
@@ -215,9 +231,10 @@ def worker_internal_error(self, node, formatted_error):
             excrepr = excinfo.getrepr()
             self.config.hook.pytest_internalerror(excrepr=excrepr, excinfo=excinfo)
 
-    def worker_errordown(self, node, error):
+    def worker_errordown(self, node: WorkerController, error: object | None) -> None:
         """Emitted by the WorkerController when a node dies."""
         self.config.hook.pytest_testnodedown(node=node, error=error)
+        assert self.sched is not None
         try:
             crashitem = self.sched.remove_node(node)
         except KeyError:
@@ -235,7 +252,7 @@ def worker_errordown(self, node, error):
             if self._max_worker_restart == 0:
                 msg = f"worker {node.gateway.id} crashed and worker restarting disabled"
             else:
-                msg = "maximum crashed workers reached: %d" % self._max_worker_restart
+                msg = f"maximum crashed workers reached: {self._max_worker_restart}"
             self._summary_report = msg
             self.report_line("\n" + msg)
             self.triggershutdown()
@@ -246,11 +263,13 @@ def worker_errordown(self, node, error):
         self._active_nodes.remove(node)
 
     @pytest.hookimpl
-    def pytest_terminal_summary(self, terminalreporter):
+    def pytest_terminal_summary(self, terminalreporter: Any) -> None:
         if self.config.option.verbose >= 0 and self._summary_report:
             terminalreporter.write_sep("=", f"xdist: {self._summary_report}")
 
-    def worker_collectionfinish(self, node, ids):
+    def worker_collectionfinish(
+        self, node: WorkerController, ids: Sequence[str]
+    ) -> None:
         """Worker has finished test collection.
 
         This adds the collection for this node to the scheduler.  If
@@ -264,7 +283,9 @@ def worker_collectionfinish(self, node, ids):
         self.config.hook.pytest_xdist_node_collection_finished(node=node, ids=ids)
         # tell session which items were effectively collected otherwise
         # the controller node will finish the session with EXIT_NOTESTSCOLLECTED
+        assert self._session is not None
         self._session.testscollected = len(ids)
+        assert self.sched is not None
         self.sched.add_node_collection(node, ids)
         if self.terminal:
             self.trdist.setstatus(
@@ -280,29 +301,44 @@ def worker_collectionfinish(self, node, ids):
                     )
             self.sched.schedule()
 
-    def worker_logstart(self, node, nodeid, location):
+    def worker_logstart(
+        self,
+        node: WorkerController,
+        nodeid: str,
+        location: tuple[str, int | None, str],
+    ) -> None:
         """Emitted when a node calls the pytest_runtest_logstart hook."""
         self.config.hook.pytest_runtest_logstart(nodeid=nodeid, location=location)
 
-    def worker_logfinish(self, node, nodeid, location):
+    def worker_logfinish(
+        self,
+        node: WorkerController,
+        nodeid: str,
+        location: tuple[str, int | None, str],
+    ) -> None:
         """Emitted when a node calls the pytest_runtest_logfinish hook."""
         self.config.hook.pytest_runtest_logfinish(nodeid=nodeid, location=location)
 
-    def worker_testreport(self, node, rep):
+    def worker_testreport(self, node: WorkerController, rep: pytest.TestReport) -> None:
         """Emitted when a node calls the pytest_runtest_logreport hook."""
-        rep.node = node
+        rep.node = node  # type: ignore[attr-defined]
         self.config.hook.pytest_runtest_logreport(report=rep)
         self._handlefailures(rep)
 
-    def worker_runtest_protocol_complete(self, node, item_index, duration):
+    def worker_runtest_protocol_complete(
+        self, node: WorkerController, item_index: int, duration: float
+    ) -> None:
         """
         Emitted when a node fires the 'runtest_protocol_complete' event,
         signalling that a test has completed the runtestprotocol and should be
         removed from the pending list in the scheduler.
         """
+        assert self.sched is not None
         self.sched.mark_test_complete(node, item_index, duration)
 
-    def worker_unscheduled(self, node, indices):
+    def worker_unscheduled(
+        self, node: WorkerController, indices: Sequence[int]
+    ) -> None:
         """
         Emitted when a node fires the 'unscheduled' event, signalling that
         some tests have been removed from the worker's queue and should be
@@ -311,9 +347,14 @@ def worker_unscheduled(self, node, indices):
         This should happen only in response to 'steal' command, so schedulers
         not using 'steal' command don't have to implement it.
         """
+        assert self.sched is not None
         self.sched.remove_pending_tests_from_node(node, indices)
 
-    def worker_collectreport(self, node, rep):
+    def worker_collectreport(
+        self,
+        node: WorkerController,
+        rep: pytest.CollectReport | pytest.TestReport,
+    ) -> None:
         """Emitted when a node calls the pytest_collectreport hook.
 
         Because we only need the report when there's a failure/skip, as optimization
@@ -322,14 +363,20 @@ def worker_collectreport(self, node, rep):
         assert not rep.passed
         self._failed_worker_collectreport(node, rep)
 
-    def worker_warning_recorded(self, warning_message, when, nodeid, location):
+    def worker_warning_recorded(
+        self,
+        warning_message: warnings.WarningMessage,
+        when: str,
+        nodeid: str,
+        location: tuple[str, int, str] | None,
+    ) -> None:
         """Emitted when a node calls the pytest_warning_recorded hook."""
         kwargs = dict(
             warning_message=warning_message, when=when, nodeid=nodeid, location=location
         )
         self.config.hook.pytest_warning_recorded.call_historic(kwargs=kwargs)
 
-    def _clone_node(self, node):
+    def _clone_node(self, node: WorkerController) -> WorkerController:
         """Return new node based on an existing one.
 
         This is normally for when a node dies, this will copy the spec
@@ -339,12 +386,17 @@ def _clone_node(self, node):
         """
         spec = node.gateway.spec
         spec.id = None
+        assert self.nodemanager is not None
         self.nodemanager.group.allocate_id(spec)
-        node = self.nodemanager.setup_node(spec, self.queue.put)
-        self._active_nodes.add(node)
-        return node
-
-    def _failed_worker_collectreport(self, node, rep):
+        clone = self.nodemanager.setup_node(spec, self.queue.put)
+        self._active_nodes.add(clone)
+        return clone
+
+    def _failed_worker_collectreport(
+        self,
+        node: WorkerController,
+        rep: pytest.CollectReport | pytest.TestReport,
+    ) -> None:
         # Check we haven't already seen this report (from
         # another worker).
         if rep.longrepr not in self._failed_collection_errors:
@@ -352,7 +404,10 @@ def _failed_worker_collectreport(self, node, rep):
             self.config.hook.pytest_collectreport(report=rep)
             self._handlefailures(rep)
 
-    def _handlefailures(self, rep):
+    def _handlefailures(
+        self,
+        rep: pytest.CollectReport | pytest.TestReport,
+    ) -> None:
         if rep.failed:
             self.countfailures += 1
             if (
@@ -362,22 +417,28 @@ def _handlefailures(self, rep):
             ):
                 self.shouldstop = f"stopping after {self.countfailures} failures"
 
-    def triggershutdown(self):
+    def triggershutdown(self) -> None:
         if not self.shuttingdown:
             self.log("triggering shutdown")
             self.shuttingdown = True
+            assert self.sched is not None
             for node in self.sched.nodes:
                 node.shutdown()
 
-    def handle_crashitem(self, nodeid, worker):
+    def handle_crashitem(self, nodeid: str, worker: WorkerController) -> None:
         # XXX get more reporting info by recording pytest_runtest_logstart?
         # XXX count no of failures and retry N times
         fspath = nodeid.split("::")[0]
         msg = f"worker {worker.gateway.id!r} crashed while running {nodeid!r}"
         rep = pytest.TestReport(
-            nodeid, (fspath, None, fspath), (), "failed", msg, "???"
+            nodeid=nodeid,
+            location=(fspath, None, fspath),
+            keywords={},
+            outcome="failed",
+            longrepr=msg,
+            when="???",  # type: ignore[arg-type]
         )
-        rep.node = worker
+        rep.node = worker  # type: ignore[attr-defined]
 
         self.config.hook.pytest_handlecrashitem(
             crashitem=nodeid,
@@ -404,10 +465,10 @@ class WorkerStatus(Enum):
 
 
 class TerminalDistReporter:
-    def __init__(self, config) -> None:
+    def __init__(self, config: pytest.Config) -> None:
         self.config = config
         self.tr = config.pluginmanager.getplugin("terminalreporter")
-        self._status: dict[str, tuple[WorkerStatus, int]] = {}
+        self._status: dict[object, tuple[WorkerStatus, int]] = {}
         self._lastlen = 0
         self._isatty = getattr(self.tr, "isatty", self.tr.hasmarkup)
 
@@ -419,7 +480,12 @@ def ensure_show_status(self) -> None:
             self.write_line(self.getstatus())
 
     def setstatus(
-        self, spec, status: WorkerStatus, *, tests_collected: int, show: bool = True
+        self,
+        spec: execnet.XSpec,
+        status: WorkerStatus,
+        *,
+        tests_collected: int,
+        show: bool = True,
     ) -> None:
         self._status[spec.id] = (status, tests_collected)
         if show and self._isatty:
@@ -433,7 +499,7 @@ def getstatus(self) -> str:
 
         return "bringing up nodes..."
 
-    def rewrite(self, line, newline=False):
+    def rewrite(self, line: str, newline: bool = False) -> None:
         pline = line + " " * max(self._lastlen - len(line), 0)
         if newline:
             self._lastlen = 0
@@ -443,7 +509,7 @@ def rewrite(self, line, newline=False):
         self.tr.rewrite(pline, bold=True)
 
     @pytest.hookimpl
-    def pytest_xdist_setupnodes(self, specs) -> None:
+    def pytest_xdist_setupnodes(self, specs: Sequence[execnet.XSpec]) -> None:
         self._specs = specs
         for spec in specs:
             self.setstatus(spec, WorkerStatus.Created, tests_collected=0, show=False)
@@ -451,7 +517,7 @@ def pytest_xdist_setupnodes(self, specs) -> None:
         self.ensure_show_status()
 
     @pytest.hookimpl
-    def pytest_xdist_newgateway(self, gateway) -> None:
+    def pytest_xdist_newgateway(self, gateway: execnet.Gateway) -> None:
         if self.config.option.verbose > 0:
             rinfo = gateway._rinfo()
             different_interpreter = rinfo.executable != sys.executable
@@ -464,7 +530,7 @@ def pytest_xdist_newgateway(self, gateway) -> None:
         self.setstatus(gateway.spec, WorkerStatus.Initialized, tests_collected=0)
 
     @pytest.hookimpl
-    def pytest_testnodeready(self, node) -> None:
+    def pytest_testnodeready(self, node: WorkerController) -> None:
         if self.config.option.verbose > 0:
             d = node.workerinfo
             different_interpreter = d.get("executable") != sys.executable
@@ -476,23 +542,25 @@ def pytest_testnodeready(self, node) -> None:
         )
 
     @pytest.hookimpl
-    def pytest_testnodedown(self, node, error) -> None:
+    def pytest_testnodedown(self, node: WorkerController, error: object) -> None:
         if not error:
             return
         self.write_line(f"[{node.gateway.id}] node down: {error}")
 
 
-def get_default_max_worker_restart(config):
+def get_default_max_worker_restart(config: pytest.Config) -> int | None:
     """Gets the default value of --max-worker-restart option if it is not provided.
 
     Use a reasonable default to avoid workers from restarting endlessly due to crashing collections (#226).
     """
-    result = config.option.maxworkerrestart
-    if result is not None:
-        result = int(result)
+    result_str: str | None = config.option.maxworkerrestart
+    if result_str is not None:
+        result = int(result_str)
     elif config.option.numprocesses:
         # if --max-worker-restart was not provided, use a reasonable default (#226)
         result = config.option.numprocesses * 4
+    else:
+        result = None
     return result
 
 
diff --git a/src/xdist/looponfail.py b/src/xdist/looponfail.py
index 8c2a60ab..7e30e4cf 100644
--- a/src/xdist/looponfail.py
+++ b/src/xdist/looponfail.py
@@ -13,6 +13,7 @@
 from pathlib import Path
 import sys
 import time
+from typing import Any
 from typing import Sequence
 
 from _pytest._io import TerminalWriter
@@ -23,7 +24,7 @@
 
 
 @pytest.hookimpl
-def pytest_addoption(parser):
+def pytest_addoption(parser: pytest.Parser) -> None:
     group = parser.getgroup("xdist", "distributed and subprocess testing")
     group._addoption(
         "-f",
@@ -37,13 +38,14 @@ def pytest_addoption(parser):
 
 
 @pytest.hookimpl
-def pytest_cmdline_main(config):
+def pytest_cmdline_main(config: pytest.Config) -> int | None:
     if config.getoption("looponfail"):
         usepdb = config.getoption("usepdb", False)  # a core option
         if usepdb:
             raise pytest.UsageError("--pdb is incompatible with --looponfail.")
         looponfail_main(config)
         return 2  # looponfail only can get stop with ctrl-C anyway
+    return None
 
 
 def looponfail_main(config: pytest.Config) -> None:
@@ -68,19 +70,21 @@ def looponfail_main(config: pytest.Config) -> None:
 
 
 class RemoteControl:
-    def __init__(self, config):
+    gateway: execnet.Gateway
+
+    def __init__(self, config: pytest.Config) -> None:
         self.config = config
-        self.failures = []
+        self.failures: list[str] = []
 
-    def trace(self, *args):
+    def trace(self, *args: object) -> None:
         if self.config.option.debug:
             msg = " ".join(str(x) for x in args)
             print("RemoteControl:", msg)
 
-    def initgateway(self):
+    def initgateway(self) -> execnet.Gateway:
         return execnet.makegateway("popen")
 
-    def setup(self):
+    def setup(self) -> None:
         if hasattr(self, "gateway"):
             raise ValueError("already have gateway %r" % self.gateway)
         self.trace("setting up worker session")
@@ -90,17 +94,17 @@ def setup(self):
             args=self.config.args,
             option_dict=vars(self.config.option),
         )
-        remote_outchannel = channel.receive()
+        remote_outchannel: execnet.Channel = channel.receive()
 
         out = TerminalWriter()
 
-        def write(s):
+        def write(s: str) -> None:
             out._file.write(s)
             out._file.flush()
 
         remote_outchannel.setcallback(write)
 
-    def ensure_teardown(self):
+    def ensure_teardown(self) -> None:
         if hasattr(self, "channel"):
             if not self.channel.isclosed():
                 self.trace("closing", self.channel)
@@ -111,12 +115,12 @@ def ensure_teardown(self):
             self.gateway.exit()
             del self.gateway
 
-    def runsession(self):
+    def runsession(self) -> tuple[list[str], list[str], bool]:
         try:
             self.trace("sending", self.failures)
             self.channel.send(self.failures)
             try:
-                return self.channel.receive()
+                return self.channel.receive()  # type: ignore[no-any-return]
             except self.channel.RemoteError:
                 e = sys.exc_info()[1]
                 self.trace("ERROR", e)
@@ -124,7 +128,7 @@ def runsession(self):
         finally:
             self.ensure_teardown()
 
-    def loop_once(self):
+    def loop_once(self) -> None:
         self.setup()
         self.wasfailing = self.failures and len(self.failures)
         result = self.runsession()
@@ -139,7 +143,9 @@ def loop_once(self):
             self.failures = uniq_failures
 
 
-def repr_pytest_looponfailinfo(failreports, rootdirs):
+def repr_pytest_looponfailinfo(
+    failreports: Sequence[str], rootdirs: Sequence[Path]
+) -> None:
     tr = TerminalWriter()
     if failreports:
         tr.sep("#", "LOOPONFAILING", bold=True)
@@ -151,12 +157,16 @@ def repr_pytest_looponfailinfo(failreports, rootdirs):
         tr.line(f"### Watching:   {rootdir}", bold=True)
 
 
-def init_worker_session(channel, args, option_dict):
+def init_worker_session(
+    channel: "execnet.Channel",  # noqa: UP037
+    args: list[str],
+    option_dict: dict[str, "Any"],  # noqa: UP037
+) -> None:
     import os
     import sys
 
     outchannel = channel.gateway.newchannel()
-    sys.stdout = sys.stderr = outchannel.makefile("w")
+    sys.stdout = sys.stderr = outchannel.makefile("w")  # type: ignore[assignment]
     channel.send(outchannel)
     # prune sys.path to not contain relative paths
     newpaths = []
@@ -179,21 +189,21 @@ def init_worker_session(channel, args, option_dict):
 
 
 class WorkerFailSession:
-    def __init__(self, config, channel):
+    def __init__(self, config: pytest.Config, channel: execnet.Channel) -> None:
         self.config = config
         self.channel = channel
-        self.recorded_failures = []
+        self.recorded_failures: list[pytest.CollectReport | pytest.TestReport] = []
         self.collection_failed = False
         config.pluginmanager.register(self)
         config.option.looponfail = False
         config.option.usepdb = False
 
-    def DEBUG(self, *args):
+    def DEBUG(self, *args: object) -> None:
         if self.config.option.debug:
             print(" ".join(map(str, args)))
 
     @pytest.hookimpl
-    def pytest_collection(self, session):
+    def pytest_collection(self, session: pytest.Session) -> bool:
         self.session = session
         self.trails = self.current_command
         hook = self.session.ihook
@@ -208,17 +218,17 @@ def pytest_collection(self, session):
         return True
 
     @pytest.hookimpl
-    def pytest_runtest_logreport(self, report):
+    def pytest_runtest_logreport(self, report: pytest.TestReport) -> None:
         if report.failed:
             self.recorded_failures.append(report)
 
     @pytest.hookimpl
-    def pytest_collectreport(self, report):
+    def pytest_collectreport(self, report: pytest.CollectReport) -> None:
         if report.failed:
             self.recorded_failures.append(report)
             self.collection_failed = True
 
-    def main(self):
+    def main(self) -> None:
         self.DEBUG("WORKER: received configuration, waiting for command trails")
         try:
             command = self.channel.receive()
@@ -233,7 +243,8 @@ def main(self):
             loc = rep.longrepr
             loc = str(getattr(loc, "reprcrash", loc))
             failreports.append(loc)
-        self.channel.send((trails, failreports, self.collection_failed))
+        result = (trails, failreports, self.collection_failed)
+        self.channel.send(result)
 
 
 class StatRecorder:
@@ -248,7 +259,7 @@ def fil(self, p: Path) -> bool:
     def rec(self, p: Path) -> bool:
         return not p.name.startswith(".") and p.exists()
 
-    def waitonchange(self, checkinterval=1.0):
+    def waitonchange(self, checkinterval: float = 1.0) -> None:
         while 1:
             changed = self.check()
             if changed:
diff --git a/src/xdist/newhooks.py b/src/xdist/newhooks.py
index ceac11ed..5bfce7c4 100644
--- a/src/xdist/newhooks.py
+++ b/src/xdist/newhooks.py
@@ -12,16 +12,32 @@
     http://pytest.org/en/latest/writing_plugins.html#optionally-using-hooks-from-3rd-party-plugins
 """
 
+from __future__ import annotations
+
+import os
+from typing import Any
+from typing import Sequence
+from typing import TYPE_CHECKING
+
+import execnet
 import pytest
 
 
+if TYPE_CHECKING:
+    from xdist.remote import Producer
+    from xdist.scheduler.protocol import Scheduling
+    from xdist.workermanage import WorkerController
+
+
 @pytest.hookspec()
-def pytest_xdist_setupnodes(config, specs):
+def pytest_xdist_setupnodes(
+    config: pytest.Config, specs: Sequence[execnet.XSpec]
+) -> None:
     """Called before any remote node is set up."""
 
 
 @pytest.hookspec()
-def pytest_xdist_newgateway(gateway):
+def pytest_xdist_newgateway(gateway: execnet.Gateway) -> None:
     """Called on new raw gateway creation."""
 
 
@@ -30,7 +46,10 @@ def pytest_xdist_newgateway(gateway):
         "rsync feature is deprecated and will be removed in pytest-xdist 4.0"
     )
 )
-def pytest_xdist_rsyncstart(source, gateways):
+def pytest_xdist_rsyncstart(
+    source: str | os.PathLike[str],
+    gateways: Sequence[execnet.Gateway],
+) -> None:
     """Called before rsyncing a directory to remote gateways takes place."""
 
 
@@ -39,52 +58,62 @@ def pytest_xdist_rsyncstart(source, gateways):
         "rsync feature is deprecated and will be removed in pytest-xdist 4.0"
     )
 )
-def pytest_xdist_rsyncfinish(source, gateways):
+def pytest_xdist_rsyncfinish(
+    source: str | os.PathLike[str],
+    gateways: Sequence[execnet.Gateway],
+) -> None:
     """Called after rsyncing a directory to remote gateways takes place."""
 
 
 @pytest.hookspec(firstresult=True)
-def pytest_xdist_getremotemodule():
+def pytest_xdist_getremotemodule() -> Any:
     """Called when creating remote node."""
 
 
 @pytest.hookspec()
-def pytest_configure_node(node):
+def pytest_configure_node(node: WorkerController) -> None:
     """Configure node information before it gets instantiated."""
 
 
 @pytest.hookspec()
-def pytest_testnodeready(node):
+def pytest_testnodeready(node: WorkerController) -> None:
     """Test Node is ready to operate."""
 
 
 @pytest.hookspec()
-def pytest_testnodedown(node, error):
+def pytest_testnodedown(node: WorkerController, error: object | None) -> None:
     """Test Node is down."""
 
 
 @pytest.hookspec()
-def pytest_xdist_node_collection_finished(node, ids):
+def pytest_xdist_node_collection_finished(
+    node: WorkerController, ids: Sequence[str]
+) -> None:
     """Called by the controller node when a worker node finishes collecting."""
 
 
 @pytest.hookspec(firstresult=True)
-def pytest_xdist_make_scheduler(config, log):
+def pytest_xdist_make_scheduler(
+    config: pytest.Config, log: Producer
+) -> Scheduling | None:
     """Return a node scheduler implementation."""
 
 
 @pytest.hookspec(firstresult=True)
-def pytest_xdist_auto_num_workers(config):
+def pytest_xdist_auto_num_workers(config: pytest.Config) -> int:
     """
     Return the number of workers to spawn when ``--numprocesses=auto`` is given in the
     command-line.
 
     .. versionadded:: 2.1
     """
+    raise NotImplementedError()
 
 
 @pytest.hookspec(firstresult=True)
-def pytest_handlecrashitem(crashitem, report, sched):
+def pytest_handlecrashitem(
+    crashitem: str, report: pytest.TestReport, sched: Scheduling
+) -> None:
     """
     Handle a crashitem, modifying the report if necessary.
 
diff --git a/src/xdist/plugin.py b/src/xdist/plugin.py
index 14d081f7..f670d9de 100644
--- a/src/xdist/plugin.py
+++ b/src/xdist/plugin.py
@@ -1,5 +1,8 @@
+from __future__ import annotations
+
 import os
 import sys
+from typing import Literal
 import uuid
 import warnings
 
@@ -10,7 +13,7 @@
 
 
 @pytest.hookimpl
-def pytest_xdist_auto_num_workers(config):
+def pytest_xdist_auto_num_workers(config: pytest.Config) -> int:
     env_var = os.environ.get("PYTEST_XDIST_AUTO_NUM_WORKERS")
     if env_var:
         try:
@@ -25,14 +28,14 @@ def pytest_xdist_auto_num_workers(config):
     except ImportError:
         pass
     else:
-        use_logical = config.option.numprocesses == "logical"
+        use_logical: bool = config.option.numprocesses == "logical"
         count = psutil.cpu_count(logical=use_logical) or psutil.cpu_count()
         if count:
             return count
     try:
         from os import sched_getaffinity
 
-        def cpu_count():
+        def cpu_count() -> int:
             return len(sched_getaffinity(0))
 
     except ImportError:
@@ -40,7 +43,7 @@ def cpu_count():
             # workaround https://bitbucket.org/pypy/pypy/issues/2375
             return 2
         try:
-            from os import cpu_count
+            from os import cpu_count  # type: ignore[assignment]
         except ImportError:
             from multiprocessing import cpu_count
     try:
@@ -50,15 +53,15 @@ def cpu_count():
     return n if n else 1
 
 
-def parse_numprocesses(s):
+def parse_numprocesses(s: str) -> int | Literal["auto", "logical"]:
     if s in ("auto", "logical"):
-        return s
+        return s  # type: ignore[return-value]
     elif s is not None:
         return int(s)
 
 
 @pytest.hookimpl
-def pytest_addoption(parser):
+def pytest_addoption(parser: pytest.Parser) -> None:
     # 'Help' formatting (same rules as pytest's):
     # Start with capitalized letters.
     # If a single phrase, do not end with period. If more than one phrase, all phrases end with periods.
@@ -206,7 +209,7 @@ def pytest_addoption(parser):
 
 
 @pytest.hookimpl
-def pytest_addhooks(pluginmanager):
+def pytest_addhooks(pluginmanager: pytest.PytestPluginManager) -> None:
     from xdist import newhooks
 
     pluginmanager.add_hookspecs(newhooks)
@@ -218,7 +221,7 @@ def pytest_addhooks(pluginmanager):
 
 
 @pytest.hookimpl(trylast=True)
-def pytest_configure(config):
+def pytest_configure(config: pytest.Config) -> None:
     config_line = (
         "xdist_group: specify group for tests should run in same session."
         "in relation to one another. Provided by pytest-xdist."
@@ -256,16 +259,13 @@ def pytest_configure(config):
         config.issue_config_time_warning(warning, 2)
 
 
-def _is_distribution_mode(config):
-    """Return `True` if distribution mode is on, `False` otherwise.
-
-    :param config: the `pytest` `config` object
-    """
-    return config.getoption("dist") != "no" and config.getoption("tx")
+def _is_distribution_mode(config: pytest.Config) -> bool:
+    """Whether distribution mode is on."""
+    return config.getoption("dist") != "no" and bool(config.getoption("tx"))
 
 
 @pytest.hookimpl(tryfirst=True)
-def pytest_cmdline_main(config):
+def pytest_cmdline_main(config: pytest.Config) -> None:
     if config.option.distload:
         config.option.dist = "load"
 
@@ -302,7 +302,9 @@ def pytest_cmdline_main(config):
 # -------------------------------------------------------------------------
 
 
-def is_xdist_worker(request_or_session) -> bool:
+def is_xdist_worker(
+    request_or_session: pytest.FixtureRequest | pytest.Session,
+) -> bool:
     """Return `True` if this is an xdist worker, `False` otherwise.
 
     :param request_or_session: the `pytest` `request` or `session` object
@@ -310,7 +312,9 @@ def is_xdist_worker(request_or_session) -> bool:
     return hasattr(request_or_session.config, "workerinput")
 
 
-def is_xdist_controller(request_or_session) -> bool:
+def is_xdist_controller(
+    request_or_session: pytest.FixtureRequest | pytest.Session,
+) -> bool:
     """Return `True` if this is the xdist controller, `False` otherwise.
 
     Note: this method also returns `False` when distribution has not been
@@ -328,7 +332,9 @@ def is_xdist_controller(request_or_session) -> bool:
 is_xdist_master = is_xdist_controller
 
 
-def get_xdist_worker_id(request_or_session):
+def get_xdist_worker_id(
+    request_or_session: pytest.FixtureRequest | pytest.Session,
+) -> str:
     """Return the id of the current worker ('gw0', 'gw1', etc) or 'master'
     if running on the controller node.
 
@@ -338,14 +344,15 @@ def get_xdist_worker_id(request_or_session):
     :param request_or_session: the `pytest` `request` or `session` object
     """
     if hasattr(request_or_session.config, "workerinput"):
-        return request_or_session.config.workerinput["workerid"]
+        workerid: str = request_or_session.config.workerinput["workerid"]
+        return workerid
     else:
         # TODO: remove "master", ideally for a None
         return "master"
 
 
 @pytest.fixture(scope="session")
-def worker_id(request):
+def worker_id(request: pytest.FixtureRequest) -> str:
     """Return the id of the current worker ('gw0', 'gw1', etc) or 'master'
     if running on the master node.
     """
@@ -354,9 +361,10 @@ def worker_id(request):
 
 
 @pytest.fixture(scope="session")
-def testrun_uid(request):
+def testrun_uid(request: pytest.FixtureRequest) -> str:
     """Return the unique id of the current test."""
     if hasattr(request.config, "workerinput"):
-        return request.config.workerinput["testrunuid"]
+        testrunid: str = request.config.workerinput["testrunuid"]
+        return testrunid
     else:
         return uuid.uuid4().hex
diff --git a/src/xdist/remote.py b/src/xdist/remote.py
index ac1bf1ca..dd1f9883 100644
--- a/src/xdist/remote.py
+++ b/src/xdist/remote.py
@@ -6,16 +6,22 @@
 needs not to be installed in remote environments.
 """
 
+from __future__ import annotations
+
 import contextlib
 import enum
 import os
 import sys
 import time
 from typing import Any
+from typing import Generator
+from typing import Literal
+from typing import Sequence
+from typing import TypedDict
+import warnings
 
 from _pytest.config import _prepareconfig
-from execnet.gateway_base import DumpError
-from execnet.gateway_base import dumps
+import execnet
 import pytest
 
 
@@ -23,7 +29,7 @@
     from setproctitle import setproctitle
 except ImportError:
 
-    def setproctitle(title):
+    def setproctitle(title: str) -> None:
         pass
 
 
@@ -35,7 +41,7 @@ class Producer:
     to have the other way around.
     """
 
-    def __init__(self, name: str, *, enabled: bool = True):
+    def __init__(self, name: str, *, enabled: bool = True) -> None:
         self.name = name
         self.enabled = enabled
 
@@ -46,11 +52,11 @@ def __call__(self, *a: Any, **k: Any) -> None:
         if self.enabled:
             print(f"[{self.name}]", *a, **k, file=sys.stderr)
 
-    def __getattr__(self, name: str) -> "Producer":
+    def __getattr__(self, name: str) -> Producer:
         return type(self)(name, enabled=self.enabled)
 
 
-def worker_title(title):
+def worker_title(title: str) -> None:
     try:
         setproctitle(title)
     except Exception:
@@ -64,59 +70,63 @@ class Marker(enum.Enum):
 
 
 class WorkerInteractor:
-    def __init__(self, config, channel):
+    def __init__(self, config: pytest.Config, channel: execnet.Channel) -> None:
         self.config = config
-        self.workerid = config.workerinput.get("workerid", "?")
-        self.testrunuid = config.workerinput["testrunuid"]
+        workerinput: dict[str, Any] = config.workerinput  # type: ignore[attr-defined]
+        self.workerid = workerinput.get("workerid", "?")
+        self.testrunuid = workerinput["testrunuid"]
         self.log = Producer(f"worker-{self.workerid}", enabled=config.option.debug)
         self.channel = channel
         self.torun = self._make_queue()
-        self.nextitem_index = None
+        self.nextitem_index: int | None | Literal[Marker.SHUTDOWN] = None
         config.pluginmanager.register(self)
 
-    def _make_queue(self):
+    def _make_queue(self) -> Any:
         return self.channel.gateway.execmodel.queue.Queue()
 
-    def _get_next_item_index(self):
+    def _get_next_item_index(self) -> int | Literal[Marker.SHUTDOWN]:
         """Gets the next item from test queue. Handles the case when the queue
         is replaced concurrently in another thread.
         """
         result = self.torun.get()
         while result is Marker.QUEUE_REPLACED:
             result = self.torun.get()
-        return result
+        return result  # type: ignore[no-any-return]
 
-    def sendevent(self, name, **kwargs):
+    def sendevent(self, name: str, **kwargs: object) -> None:
         self.log("sending", name, kwargs)
         self.channel.send((name, kwargs))
 
     @pytest.hookimpl
-    def pytest_internalerror(self, excrepr):
+    def pytest_internalerror(self, excrepr: object) -> None:
         formatted_error = str(excrepr)
         for line in formatted_error.split("\n"):
             self.log("IERROR>", line)
         interactor.sendevent("internal_error", formatted_error=formatted_error)
 
     @pytest.hookimpl
-    def pytest_sessionstart(self, session):
+    def pytest_sessionstart(self, session: pytest.Session) -> None:
         self.session = session
         workerinfo = getinfodict()
         self.sendevent("workerready", workerinfo=workerinfo)
 
     @pytest.hookimpl(hookwrapper=True)
-    def pytest_sessionfinish(self, exitstatus):
+    def pytest_sessionfinish(self, exitstatus: int) -> Generator[None, object, None]:
+        workeroutput: dict[str, Any] = self.config.workeroutput  # type: ignore[attr-defined]
         # in pytest 5.0+, exitstatus is an IntEnum object
-        self.config.workeroutput["exitstatus"] = int(exitstatus)
-        self.config.workeroutput["shouldfail"] = self.session.shouldfail
-        self.config.workeroutput["shouldstop"] = self.session.shouldstop
+        workeroutput["exitstatus"] = int(exitstatus)
+        workeroutput["shouldfail"] = self.session.shouldfail
+        workeroutput["shouldstop"] = self.session.shouldstop
         yield
-        self.sendevent("workerfinished", workeroutput=self.config.workeroutput)
+        self.sendevent("workerfinished", workeroutput=workeroutput)
 
     @pytest.hookimpl
-    def pytest_collection(self, session):
+    def pytest_collection(self) -> None:
         self.sendevent("collectionstart")
 
-    def handle_command(self, command):
+    def handle_command(
+        self, command: tuple[str, dict[str, Any]] | Literal[Marker.SHUTDOWN]
+    ) -> None:
         if command is Marker.SHUTDOWN:
             self.torun.put(Marker.SHUTDOWN)
             return
@@ -135,18 +145,19 @@ def handle_command(self, command):
         elif name == "steal":
             self.steal(kwargs["indices"])
 
-    def steal(self, indices):
-        indices = set(indices)
+    def steal(self, indices: Sequence[int]) -> None:
+        indices_set = set(indices)
         stolen = []
 
         old_queue, self.torun = self.torun, self._make_queue()
 
-        def old_queue_get_nowait_noraise():
+        def old_queue_get_nowait_noraise() -> int | None:
             with contextlib.suppress(self.channel.gateway.execmodel.queue.Empty):
-                return old_queue.get_nowait()
+                return old_queue.get_nowait()  # type: ignore[no-any-return]
+            return None
 
         for i in iter(old_queue_get_nowait_noraise, None):
-            if i in indices:
+            if i in indices_set:
                 stolen.append(i)
             else:
                 self.torun.put(i)
@@ -155,7 +166,7 @@ def old_queue_get_nowait_noraise():
         old_queue.put(Marker.QUEUE_REPLACED)
 
     @pytest.hookimpl
-    def pytest_runtestloop(self, session):
+    def pytest_runtestloop(self, session: pytest.Session) -> bool:
         self.log("entering main loop")
         self.channel.setcallback(self.handle_command, endmarker=Marker.SHUTDOWN)
         self.nextitem_index = self._get_next_item_index()
@@ -165,7 +176,8 @@ def pytest_runtestloop(self, session):
                 break
         return True
 
-    def run_one_test(self):
+    def run_one_test(self) -> None:
+        assert isinstance(self.nextitem_index, int)
         self.item_index = self.nextitem_index
         self.nextitem_index = self._get_next_item_index()
 
@@ -174,6 +186,7 @@ def run_one_test(self):
         if self.nextitem_index is Marker.SHUTDOWN:
             nextitem = None
         else:
+            assert self.nextitem_index is not None
             nextitem = items[self.nextitem_index]
 
         worker_title("[pytest-xdist running] %s" % item.nodeid)
@@ -188,7 +201,11 @@ def run_one_test(self):
             "runtest_protocol_complete", item_index=self.item_index, duration=duration
         )
 
-    def pytest_collection_modifyitems(self, session, config, items):
+    def pytest_collection_modifyitems(
+        self,
+        config: pytest.Config,
+        items: list[pytest.Item],
+    ) -> None:
         # add the group name to nodeid as suffix if --dist=loadgroup
         if config.getvalue("loadgroup"):
             for item in items:
@@ -203,7 +220,7 @@ def pytest_collection_modifyitems(self, session, config, items):
                 item._nodeid = f"{item.nodeid}@{gname}"
 
     @pytest.hookimpl
-    def pytest_collection_finish(self, session):
+    def pytest_collection_finish(self, session: pytest.Session) -> None:
         self.sendevent(
             "collectionfinish",
             topdir=str(self.config.rootpath),
@@ -211,15 +228,23 @@ def pytest_collection_finish(self, session):
         )
 
     @pytest.hookimpl
-    def pytest_runtest_logstart(self, nodeid, location):
+    def pytest_runtest_logstart(
+        self,
+        nodeid: str,
+        location: tuple[str, int | None, str],
+    ) -> None:
         self.sendevent("logstart", nodeid=nodeid, location=location)
 
     @pytest.hookimpl
-    def pytest_runtest_logfinish(self, nodeid, location):
+    def pytest_runtest_logfinish(
+        self,
+        nodeid: str,
+        location: tuple[str, int | None, str],
+    ) -> None:
         self.sendevent("logfinish", nodeid=nodeid, location=location)
 
     @pytest.hookimpl
-    def pytest_runtest_logreport(self, report):
+    def pytest_runtest_logreport(self, report: pytest.TestReport) -> None:
         data = self.config.hook.pytest_report_to_serializable(
             config=self.config, report=report
         )
@@ -230,7 +255,7 @@ def pytest_runtest_logreport(self, report):
         self.sendevent("testreport", data=data)
 
     @pytest.hookimpl
-    def pytest_collectreport(self, report):
+    def pytest_collectreport(self, report: pytest.CollectReport) -> None:
         # send only reports that have not passed to controller as optimization (#330)
         if not report.passed:
             data = self.config.hook.pytest_report_to_serializable(
@@ -239,7 +264,13 @@ def pytest_collectreport(self, report):
             self.sendevent("collectreport", data=data)
 
     @pytest.hookimpl
-    def pytest_warning_recorded(self, warning_message, when, nodeid, location):
+    def pytest_warning_recorded(
+        self,
+        warning_message: warnings.WarningMessage,
+        when: str,
+        nodeid: str,
+        location: tuple[str, int, str] | None,
+    ) -> None:
         self.sendevent(
             "warning_recorded",
             warning_message_data=serialize_warning_message(warning_message),
@@ -249,7 +280,9 @@ def pytest_warning_recorded(self, warning_message, when, nodeid, location):
         )
 
 
-def serialize_warning_message(warning_message):
+def serialize_warning_message(
+    warning_message: warnings.WarningMessage,
+) -> dict[str, Any]:
     if isinstance(warning_message.message, Warning):
         message_module = type(warning_message.message).__module__
         message_class_name = type(warning_message.message).__name__
@@ -257,8 +290,8 @@ def serialize_warning_message(warning_message):
         # check now if we can serialize the warning arguments (#349)
         # if not, we will just use the exception message on the controller node
         try:
-            dumps(warning_message.message.args)
-        except DumpError:
+            execnet.dumps(warning_message.message.args)
+        except execnet.DumpError:
             message_args = None
         else:
             message_args = warning_message.message.args
@@ -283,27 +316,38 @@ def serialize_warning_message(warning_message):
         "category_class_name": category_class_name,
     }
     # access private _WARNING_DETAILS because the attributes vary between Python versions
-    for attr_name in warning_message._WARNING_DETAILS:
+    for attr_name in warning_message._WARNING_DETAILS:  # type: ignore[attr-defined]
         if attr_name in ("message", "category"):
             continue
         attr = getattr(warning_message, attr_name)
         # Check if we can serialize the warning detail, marking `None` otherwise
         # Note that we need to define the attr (even as `None`) to allow deserializing
         try:
-            dumps(attr)
-        except DumpError:
+            execnet.dumps(attr)
+        except execnet.DumpError:
             result[attr_name] = repr(attr)
         else:
             result[attr_name] = attr
     return result
 
 
-def getinfodict():
+class WorkerInfo(TypedDict):
+    version: str
+    version_info: tuple[int, int, int, str, int]
+    sysplatform: str
+    platform: str
+    executable: str
+    cwd: str
+    id: str
+    spec: execnet.XSpec
+
+
+def getinfodict() -> WorkerInfo:
     import platform
 
     return dict(
         version=sys.version,
-        version_info=tuple(sys.version_info),
+        version_info=tuple(sys.version_info),  # type: ignore[typeddict-item]
         sysplatform=sys.platform,
         platform=platform.platform(),
         executable=sys.executable,
@@ -311,7 +355,7 @@ def getinfodict():
     )
 
 
-def setup_config(config, basetemp):
+def setup_config(config: pytest.Config, basetemp: str | None) -> None:
     config.option.loadgroup = config.getvalue("dist") == "loadgroup"
     config.option.looponfail = False
     config.option.usepdb = False
@@ -323,7 +367,7 @@ def setup_config(config, basetemp):
 
 
 if __name__ == "__channelexec__":
-    channel = channel  # type: ignore[name-defined] # noqa: F821, PLW0127
+    channel: execnet.Channel = channel  # type: ignore[name-defined] # noqa: F821, PLW0127
     workerinput, args, option_dict, change_sys_path = channel.receive()  # type: ignore[name-defined]
 
     if change_sys_path is None:
diff --git a/src/xdist/report.py b/src/xdist/report.py
index d956577d..eb463abd 100644
--- a/src/xdist/report.py
+++ b/src/xdist/report.py
@@ -1,7 +1,15 @@
+from __future__ import annotations
+
 from difflib import unified_diff
+from typing import Sequence
 
 
-def report_collection_diff(from_collection, to_collection, from_id, to_id):
+def report_collection_diff(
+    from_collection: Sequence[str],
+    to_collection: Sequence[str],
+    from_id: str,
+    to_id: str,
+) -> str | None:
     """Report the collected test difference between two nodes.
 
     :returns: detailed message describing the difference between the given
diff --git a/src/xdist/scheduler/each.py b/src/xdist/scheduler/each.py
index 47f7add3..aa4f7ba1 100644
--- a/src/xdist/scheduler/each.py
+++ b/src/xdist/scheduler/each.py
@@ -1,6 +1,13 @@
+from __future__ import annotations
+
+from typing import Sequence
+
+import pytest
+
 from xdist.remote import Producer
 from xdist.report import report_collection_diff
 from xdist.workermanage import parse_spec_config
+from xdist.workermanage import WorkerController
 
 
 class EachScheduling:
@@ -17,13 +24,13 @@ class EachScheduling:
     assigned the remaining items from the removed node.
     """
 
-    def __init__(self, config, log=None):
+    def __init__(self, config: pytest.Config, log: Producer | None = None) -> None:
         self.config = config
         self.numnodes = len(parse_spec_config(config))
-        self.node2collection = {}
-        self.node2pending = {}
-        self._started = []
-        self._removed2pending = {}
+        self.node2collection: dict[WorkerController, list[str]] = {}
+        self.node2pending: dict[WorkerController, list[int]] = {}
+        self._started: list[WorkerController] = []
+        self._removed2pending: dict[WorkerController, list[int]] = {}
         if log is None:
             self.log = Producer("eachsched")
         else:
@@ -31,12 +38,12 @@ def __init__(self, config, log=None):
         self.collection_is_completed = False
 
     @property
-    def nodes(self):
+    def nodes(self) -> list[WorkerController]:
         """A list of all nodes in the scheduler."""
         return list(self.node2pending.keys())
 
     @property
-    def tests_finished(self):
+    def tests_finished(self) -> bool:
         if not self.collection_is_completed:
             return False
         if self._removed2pending:
@@ -47,7 +54,7 @@ def tests_finished(self):
         return True
 
     @property
-    def has_pending(self):
+    def has_pending(self) -> bool:
         """Return True if there are pending test items.
 
         This indicates that collection has finished and nodes are
@@ -59,11 +66,13 @@ def has_pending(self):
                 return True
         return False
 
-    def add_node(self, node):
+    def add_node(self, node: WorkerController) -> None:
         assert node not in self.node2pending
         self.node2pending[node] = []
 
-    def add_node_collection(self, node, collection):
+    def add_node_collection(
+        self, node: WorkerController, collection: Sequence[str]
+    ) -> None:
         """Add the collected test items from a node.
 
         Collection is complete once all nodes have submitted their
@@ -97,26 +106,32 @@ def add_node_collection(self, node, collection):
                     self.node2pending[node] = pending
                     break
 
-    def mark_test_complete(self, node, item_index, duration=0):
+    def mark_test_complete(
+        self, node: WorkerController, item_index: int, duration: float = 0
+    ) -> None:
         self.node2pending[node].remove(item_index)
 
-    def mark_test_pending(self, item):
+    def mark_test_pending(self, item: str) -> None:
         raise NotImplementedError()
 
-    def remove_pending_tests_from_node(self, node, indices):
+    def remove_pending_tests_from_node(
+        self,
+        node: WorkerController,
+        indices: Sequence[int],
+    ) -> None:
         raise NotImplementedError()
 
-    def remove_node(self, node):
+    def remove_node(self, node: WorkerController) -> str | None:
         # KeyError if we didn't get an add_node() yet
         pending = self.node2pending.pop(node)
         if not pending:
-            return
+            return None
         crashitem = self.node2collection[node][pending.pop(0)]
         if pending:
             self._removed2pending[node] = pending
         return crashitem
 
-    def schedule(self):
+    def schedule(self) -> None:
         """Schedule the test items on the nodes.
 
         If the node's pending list is empty it is a new node which
diff --git a/src/xdist/scheduler/load.py b/src/xdist/scheduler/load.py
index fb9bdfdc..9d153bb9 100644
--- a/src/xdist/scheduler/load.py
+++ b/src/xdist/scheduler/load.py
@@ -1,10 +1,14 @@
+from __future__ import annotations
+
 from itertools import cycle
+from typing import Sequence
 
 import pytest
 
 from xdist.remote import Producer
 from xdist.report import report_collection_diff
 from xdist.workermanage import parse_spec_config
+from xdist.workermanage import WorkerController
 
 
 class LoadScheduling:
@@ -53,12 +57,12 @@ class LoadScheduling:
     :config: Config object, used for handling hooks.
     """
 
-    def __init__(self, config, log=None):
+    def __init__(self, config: pytest.Config, log: Producer | None = None) -> None:
         self.numnodes = len(parse_spec_config(config))
-        self.node2collection = {}
-        self.node2pending = {}
-        self.pending = []
-        self.collection = None
+        self.node2collection: dict[WorkerController, list[str]] = {}
+        self.node2pending: dict[WorkerController, list[int]] = {}
+        self.pending: list[int] = []
+        self.collection: list[str] | None = None
         if log is None:
             self.log = Producer("loadsched")
         else:
@@ -67,12 +71,12 @@ def __init__(self, config, log=None):
         self.maxschedchunk = self.config.getoption("maxschedchunk")
 
     @property
-    def nodes(self):
+    def nodes(self) -> list[WorkerController]:
         """A list of all nodes in the scheduler."""
         return list(self.node2pending.keys())
 
     @property
-    def collection_is_completed(self):
+    def collection_is_completed(self) -> bool:
         """Boolean indication initial test collection is complete.
 
         This is a boolean indicating all initial participating nodes
@@ -82,7 +86,7 @@ def collection_is_completed(self):
         return len(self.node2collection) >= self.numnodes
 
     @property
-    def tests_finished(self):
+    def tests_finished(self) -> bool:
         """Return True if all tests have been executed by the nodes."""
         if not self.collection_is_completed:
             return False
@@ -94,7 +98,7 @@ def tests_finished(self):
         return True
 
     @property
-    def has_pending(self):
+    def has_pending(self) -> bool:
         """Return True if there are pending test items.
 
         This indicates that collection has finished and nodes are
@@ -108,7 +112,7 @@ def has_pending(self):
                 return True
         return False
 
-    def add_node(self, node):
+    def add_node(self, node: WorkerController) -> None:
         """Add a new node to the scheduler.
 
         From now on the node will be allocated chunks of tests to
@@ -120,7 +124,9 @@ def add_node(self, node):
         assert node not in self.node2pending
         self.node2pending[node] = []
 
-    def add_node_collection(self, node, collection):
+    def add_node_collection(
+        self, node: WorkerController, collection: Sequence[str]
+    ) -> None:
         """Add the collected test items from a node.
 
         The collection is stored in the ``.node2collection`` map.
@@ -141,7 +147,9 @@ def add_node_collection(self, node, collection):
                 return
         self.node2collection[node] = list(collection)
 
-    def mark_test_complete(self, node, item_index, duration=0):
+    def mark_test_complete(
+        self, node: WorkerController, item_index: int, duration: float = 0
+    ) -> None:
         """Mark test item as completed by node.
 
         The duration it took to execute the item is used as a hint to
@@ -152,7 +160,8 @@ def mark_test_complete(self, node, item_index, duration=0):
         self.node2pending[node].remove(item_index)
         self.check_schedule(node, duration=duration)
 
-    def mark_test_pending(self, item):
+    def mark_test_pending(self, item: str) -> None:
+        assert self.collection is not None
         self.pending.insert(
             0,
             self.collection.index(item),
@@ -160,10 +169,14 @@ def mark_test_pending(self, item):
         for node in self.node2pending:
             self.check_schedule(node)
 
-    def remove_pending_tests_from_node(self, node, indices):
+    def remove_pending_tests_from_node(
+        self,
+        node: WorkerController,
+        indices: Sequence[int],
+    ) -> None:
         raise NotImplementedError()
 
-    def check_schedule(self, node, duration=0):
+    def check_schedule(self, node: WorkerController, duration: float = 0) -> None:
         """Maybe schedule new items on the node.
 
         If there are any globally pending nodes left then this will
@@ -197,7 +210,7 @@ def check_schedule(self, node, duration=0):
 
         self.log("num items waiting for node:", len(self.pending))
 
-    def remove_node(self, node):
+    def remove_node(self, node: WorkerController) -> str | None:
         """Remove a node from the scheduler.
 
         This should be called either when the node crashed or at
@@ -212,16 +225,17 @@ def remove_node(self, node):
         """
         pending = self.node2pending.pop(node)
         if not pending:
-            return
+            return None
 
         # The node crashed, reassing pending items
+        assert self.collection is not None
         crashitem = self.collection[pending.pop(0)]
         self.pending.extend(pending)
         for node in self.node2pending:
             self.check_schedule(node)
         return crashitem
 
-    def schedule(self):
+    def schedule(self) -> None:
         """Initiate distribution of the test collection.
 
         Initiate scheduling of the items across the nodes.  If this
@@ -285,14 +299,14 @@ def schedule(self):
             for node in self.nodes:
                 node.shutdown()
 
-    def _send_tests(self, node, num):
+    def _send_tests(self, node: WorkerController, num: int) -> None:
         tests_per_node = self.pending[:num]
         if tests_per_node:
             del self.pending[:num]
             self.node2pending[node].extend(tests_per_node)
             node.send_runtest_some(tests_per_node)
 
-    def _check_nodes_have_same_collection(self):
+    def _check_nodes_have_same_collection(self) -> bool:
         """Return True if all nodes have collected the same items.
 
         If collections differ, this method returns False while logging
diff --git a/src/xdist/scheduler/loadfile.py b/src/xdist/scheduler/loadfile.py
index 25b72da4..fb6f027f 100644
--- a/src/xdist/scheduler/loadfile.py
+++ b/src/xdist/scheduler/loadfile.py
@@ -1,3 +1,7 @@
+from __future__ import annotations
+
+import pytest
+
 from xdist.remote import Producer
 
 from .loadscope import LoadScopeScheduling
@@ -21,14 +25,14 @@ class LoadFileScheduling(LoadScopeScheduling):
     This class behaves very much like LoadScopeScheduling, but with a file-level scope.
     """
 
-    def __init__(self, config, log=None):
+    def __init__(self, config: pytest.Config, log: Producer | None = None) -> None:
         super().__init__(config, log)
         if log is None:
             self.log = Producer("loadfilesched")
         else:
             self.log = log.loadfilesched
 
-    def _split_scope(self, nodeid):
+    def _split_scope(self, nodeid: str) -> str:
         """Determine the scope (grouping) of a nodeid.
 
         There are usually 3 cases for a nodeid::
diff --git a/src/xdist/scheduler/loadgroup.py b/src/xdist/scheduler/loadgroup.py
index 1dee40e6..798c7128 100644
--- a/src/xdist/scheduler/loadgroup.py
+++ b/src/xdist/scheduler/loadgroup.py
@@ -1,3 +1,7 @@
+from __future__ import annotations
+
+import pytest
+
 from xdist.remote import Producer
 
 from .loadscope import LoadScopeScheduling
@@ -10,14 +14,14 @@ class LoadGroupScheduling(LoadScopeScheduling):
     instead of the module or class to which they belong to.
     """
 
-    def __init__(self, config, log=None):
+    def __init__(self, config: pytest.Config, log: Producer | None = None) -> None:
         super().__init__(config, log)
         if log is None:
             self.log = Producer("loadgroupsched")
         else:
             self.log = log.loadgroupsched
 
-    def _split_scope(self, nodeid):
+    def _split_scope(self, nodeid: str) -> str:
         """Determine the scope (grouping) of a nodeid.
 
         There are usually 3 cases for a nodeid::
diff --git a/src/xdist/scheduler/loadscope.py b/src/xdist/scheduler/loadscope.py
index 7c66ed51..a4d63b29 100644
--- a/src/xdist/scheduler/loadscope.py
+++ b/src/xdist/scheduler/loadscope.py
@@ -1,10 +1,15 @@
+from __future__ import annotations
+
 from collections import OrderedDict
+from typing import NoReturn
+from typing import Sequence
 
 import pytest
 
 from xdist.remote import Producer
 from xdist.report import report_collection_diff
 from xdist.workermanage import parse_spec_config
+from xdist.workermanage import WorkerController
 
 
 class LoadScopeScheduling:
@@ -85,13 +90,13 @@ class LoadScopeScheduling:
     :config: Config object, used for handling hooks.
     """
 
-    def __init__(self, config, log=None):
+    def __init__(self, config: pytest.Config, log: Producer | None = None) -> None:
         self.numnodes = len(parse_spec_config(config))
-        self.collection = None
+        self.collection: list[str] | None = None
 
-        self.workqueue = OrderedDict()
-        self.assigned_work = {}
-        self.registered_collections = {}
+        self.workqueue: OrderedDict[str, dict[str, bool]] = OrderedDict()
+        self.assigned_work: dict[WorkerController, dict[str, dict[str, bool]]] = {}
+        self.registered_collections: dict[WorkerController, list[str]] = {}
 
         if log is None:
             self.log = Producer("loadscopesched")
@@ -101,12 +106,12 @@ def __init__(self, config, log=None):
         self.config = config
 
     @property
-    def nodes(self):
+    def nodes(self) -> list[WorkerController]:
         """A list of all active nodes in the scheduler."""
         return list(self.assigned_work.keys())
 
     @property
-    def collection_is_completed(self):
+    def collection_is_completed(self) -> bool:
         """Boolean indication initial test collection is complete.
 
         This is a boolean indicating all initial participating nodes have
@@ -116,7 +121,7 @@ def collection_is_completed(self):
         return len(self.registered_collections) >= self.numnodes
 
     @property
-    def tests_finished(self):
+    def tests_finished(self) -> bool:
         """Return True if all tests have been executed by the nodes."""
         if not self.collection_is_completed:
             return False
@@ -131,7 +136,7 @@ def tests_finished(self):
         return True
 
     @property
-    def has_pending(self):
+    def has_pending(self) -> bool:
         """Return True if there are pending test items.
 
         This indicates that collection has finished and nodes are still
@@ -147,7 +152,7 @@ def has_pending(self):
 
         return False
 
-    def add_node(self, node):
+    def add_node(self, node: WorkerController) -> None:
         """Add a new node to the scheduler.
 
         From now on the node will be assigned work units to be executed.
@@ -158,7 +163,7 @@ def add_node(self, node):
         assert node not in self.assigned_work
         self.assigned_work[node] = {}
 
-    def remove_node(self, node):
+    def remove_node(self, node: WorkerController) -> str | None:
         """Remove a node from the scheduler.
 
         This should be called either when the node crashed or at shutdown time.
@@ -199,7 +204,9 @@ def remove_node(self, node):
 
         return crashitem
 
-    def add_node_collection(self, node, collection):
+    def add_node_collection(
+        self, node: WorkerController, collection: Sequence[str]
+    ) -> None:
         """Add the collected test items from a node.
 
         The collection is stored in the ``.registered_collections`` dictionary.
@@ -228,7 +235,9 @@ def add_node_collection(self, node, collection):
 
         self.registered_collections[node] = list(collection)
 
-    def mark_test_complete(self, node, item_index, duration=0):
+    def mark_test_complete(
+        self, node: WorkerController, item_index: int, duration: float = 0
+    ) -> None:
         """Mark test item as completed by node.
 
         Called by the hook:
@@ -241,13 +250,17 @@ def mark_test_complete(self, node, item_index, duration=0):
         self.assigned_work[node][scope][nodeid] = True
         self._reschedule(node)
 
-    def mark_test_pending(self, item):
+    def mark_test_pending(self, item: str) -> NoReturn:
         raise NotImplementedError()
 
-    def remove_pending_tests_from_node(self, node, indices):
+    def remove_pending_tests_from_node(
+        self,
+        node: WorkerController,
+        indices: Sequence[int],
+    ) -> None:
         raise NotImplementedError()
 
-    def _assign_work_unit(self, node):
+    def _assign_work_unit(self, node: WorkerController) -> None:
         """Assign a work unit to a node."""
         assert self.workqueue
 
@@ -268,7 +281,7 @@ def _assign_work_unit(self, node):
 
         node.send_runtest_some(nodeids_indexes)
 
-    def _split_scope(self, nodeid):
+    def _split_scope(self, nodeid: str) -> str:
         """Determine the scope (grouping) of a nodeid.
 
         There are usually 3 cases for a nodeid::
@@ -292,12 +305,12 @@ def _split_scope(self, nodeid):
         """
         return nodeid.rsplit("::", 1)[0]
 
-    def _pending_of(self, workload):
+    def _pending_of(self, workload: dict[str, dict[str, bool]]) -> int:
         """Return the number of pending tests in a workload."""
         pending = sum(list(scope.values()).count(False) for scope in workload.values())
         return pending
 
-    def _reschedule(self, node):
+    def _reschedule(self, node: WorkerController) -> None:
         """Maybe schedule new items on the node.
 
         If there are any globally pending work units left then this will check
@@ -322,7 +335,7 @@ def _reschedule(self, node):
         # Pop one unit of work and assign it
         self._assign_work_unit(node)
 
-    def schedule(self):
+    def schedule(self) -> None:
         """Initiate distribution of the test collection.
 
         Initiate scheduling of the items across the nodes.  If this gets called
@@ -352,7 +365,7 @@ def schedule(self):
             return
 
         # Determine chunks of work (scopes)
-        unsorted_workqueue = {}
+        unsorted_workqueue: dict[str, dict[str, bool]] = {}
         for nodeid in self.collection:
             scope = self._split_scope(nodeid)
             work_unit = unsorted_workqueue.setdefault(scope, {})
@@ -389,7 +402,7 @@ def schedule(self):
             for node in self.nodes:
                 node.shutdown()
 
-    def _check_nodes_have_same_collection(self):
+    def _check_nodes_have_same_collection(self) -> bool:
         """Return True if all nodes have collected the same items.
 
         If collections differ, this method returns False while logging
diff --git a/src/xdist/scheduler/worksteal.py b/src/xdist/scheduler/worksteal.py
index 5253c1a4..fd208486 100644
--- a/src/xdist/scheduler/worksteal.py
+++ b/src/xdist/scheduler/worksteal.py
@@ -1,17 +1,18 @@
 from __future__ import annotations
 
-from typing import Any
 from typing import NamedTuple
+from typing import Sequence
 
 import pytest
 
 from xdist.remote import Producer
 from xdist.report import report_collection_diff
 from xdist.workermanage import parse_spec_config
+from xdist.workermanage import WorkerController
 
 
 class NodePending(NamedTuple):
-    node: Any
+    node: WorkerController
     pending: list[int]
 
 
@@ -63,26 +64,26 @@ class WorkStealingScheduling:
        simultaneous requests.
     """
 
-    def __init__(self, config, log=None):
+    def __init__(self, config: pytest.Config, log: Producer | None = None) -> None:
         self.numnodes = len(parse_spec_config(config))
-        self.node2collection = {}
-        self.node2pending = {}
-        self.pending = []
-        self.collection = None
+        self.node2collection: dict[WorkerController, list[str]] = {}
+        self.node2pending: dict[WorkerController, list[int]] = {}
+        self.pending: list[int] = []
+        self.collection: list[str] | None = None
         if log is None:
             self.log = Producer("workstealsched")
         else:
             self.log = log.workstealsched
         self.config = config
-        self.steal_requested_from_node = None
+        self.steal_requested_from_node: WorkerController | None = None
 
     @property
-    def nodes(self):
+    def nodes(self) -> list[WorkerController]:
         """A list of all nodes in the scheduler."""
         return list(self.node2pending.keys())
 
     @property
-    def collection_is_completed(self):
+    def collection_is_completed(self) -> bool:
         """Boolean indication initial test collection is complete.
 
         This is a boolean indicating all initial participating nodes
@@ -92,7 +93,7 @@ def collection_is_completed(self):
         return len(self.node2collection) >= self.numnodes
 
     @property
-    def tests_finished(self):
+    def tests_finished(self) -> bool:
         """Return True if all tests have been executed by the nodes."""
         if not self.collection_is_completed:
             return False
@@ -106,7 +107,7 @@ def tests_finished(self):
         return True
 
     @property
-    def has_pending(self):
+    def has_pending(self) -> bool:
         """Return True if there are pending test items.
 
         This indicates that collection has finished and nodes are
@@ -120,7 +121,7 @@ def has_pending(self):
                 return True
         return False
 
-    def add_node(self, node):
+    def add_node(self, node: WorkerController) -> None:
         """Add a new node to the scheduler.
 
         From now on the node will be allocated chunks of tests to
@@ -132,7 +133,9 @@ def add_node(self, node):
         assert node not in self.node2pending
         self.node2pending[node] = []
 
-    def add_node_collection(self, node, collection):
+    def add_node_collection(
+        self, node: WorkerController, collection: Sequence[str]
+    ) -> None:
         """Add the collected test items from a node.
 
         The collection is stored in the ``.node2collection`` map.
@@ -153,7 +156,9 @@ def add_node_collection(self, node, collection):
                 return
         self.node2collection[node] = list(collection)
 
-    def mark_test_complete(self, node, item_index, duration=None):
+    def mark_test_complete(
+        self, node: WorkerController, item_index: int, duration: float | None = None
+    ) -> None:
         """Mark test item as completed by node.
 
         This is called by the ``DSession.worker_testreport`` hook.
@@ -161,14 +166,19 @@ def mark_test_complete(self, node, item_index, duration=None):
         self.node2pending[node].remove(item_index)
         self.check_schedule()
 
-    def mark_test_pending(self, item):
+    def mark_test_pending(self, item: str) -> None:
+        assert self.collection is not None
         self.pending.insert(
             0,
             self.collection.index(item),
         )
         self.check_schedule()
 
-    def remove_pending_tests_from_node(self, node, indices):
+    def remove_pending_tests_from_node(
+        self,
+        node: WorkerController,
+        indices: Sequence[int],
+    ) -> None:
         """Node returned some test indices back in response to 'steal' command.
 
         This is called by ``DSession.worker_unscheduled``.
@@ -183,7 +193,7 @@ def remove_pending_tests_from_node(self, node, indices):
         self.pending.extend(indices)
         self.check_schedule()
 
-    def check_schedule(self):
+    def check_schedule(self) -> None:
         """Reschedule tests/perform load balancing."""
         nodes_up = [
             NodePending(node, pending)
@@ -191,7 +201,7 @@ def check_schedule(self):
             if not node.shutting_down
         ]
 
-        def get_idle_nodes():
+        def get_idle_nodes() -> list[WorkerController]:
             return [node for node, pending in nodes_up if len(pending) < MIN_PENDING]
 
         idle_nodes = get_idle_nodes()
@@ -235,10 +245,11 @@ def get_idle_nodes():
                 node.shutdown()
             return
 
+        assert steal_from is not None
         steal_from.node.send_steal(steal_from.pending[-num_steal:])
         self.steal_requested_from_node = steal_from.node
 
-    def remove_node(self, node):
+    def remove_node(self, node: WorkerController) -> str | None:
         """Remove a node from the scheduler.
 
         This should be called either when the node crashed or at
@@ -249,12 +260,12 @@ def remove_node(self, node):
 
         Return the item which was being executing while the node
         crashed or None if the node has no more pending items.
-
         """
         pending = self.node2pending.pop(node)
 
         # If node was removed without completing its assigned tests - it crashed
         if pending:
+            assert self.collection is not None
             crashitem = self.collection[pending.pop(0)]
         else:
             crashitem = None
@@ -268,7 +279,7 @@ def remove_node(self, node):
         self.check_schedule()
         return crashitem
 
-    def schedule(self):
+    def schedule(self) -> None:
         """Initiate distribution of the test collection.
 
         Initiate scheduling of the items across the nodes.  If this
@@ -298,14 +309,14 @@ def schedule(self):
 
         self.check_schedule()
 
-    def _send_tests(self, node, num):
+    def _send_tests(self, node: WorkerController, num: int) -> None:
         tests_per_node = self.pending[:num]
         if tests_per_node:
             del self.pending[:num]
             self.node2pending[node].extend(tests_per_node)
             node.send_runtest_some(tests_per_node)
 
-    def _check_nodes_have_same_collection(self):
+    def _check_nodes_have_same_collection(self) -> bool:
         """Return True if all nodes have collected the same items.
 
         If collections differ, this method returns False while logging
diff --git a/src/xdist/workermanage.py b/src/xdist/workermanage.py
index c3793efb..70d95971 100644
--- a/src/xdist/workermanage.py
+++ b/src/xdist/workermanage.py
@@ -7,9 +7,12 @@
 import re
 import sys
 from typing import Any
+from typing import Callable
+from typing import Literal
 from typing import Sequence
 from typing import Union
 import uuid
+import warnings
 
 import execnet
 import pytest
@@ -17,11 +20,13 @@
 from xdist.plugin import _sys_path
 import xdist.remote
 from xdist.remote import Producer
+from xdist.remote import WorkerInfo
 
 
-def parse_spec_config(config):
+def parse_spec_config(config: pytest.Config) -> list[str]:
     xspeclist = []
-    for xspec in config.getvalue("tx"):
+    tx: list[str] = config.getvalue("tx")
+    for xspec in tx:
         i = xspec.find("*")
         try:
             num = int(xspec[:i])
@@ -40,7 +45,12 @@ class NodeManager:
     EXIT_TIMEOUT = 10
     DEFAULT_IGNORES = [".*", "*.pyc", "*.pyo", "*~"]
 
-    def __init__(self, config, specs=None, defaultchdir="pyexecnetcache") -> None:
+    def __init__(
+        self,
+        config: pytest.Config,
+        specs: Sequence[execnet.XSpec | str] | None = None,
+        defaultchdir: str = "pyexecnetcache",
+    ) -> None:
         self.config = config
         self.trace = self.config.trace.get("nodemanager")
         self.testrunuid = self.config.getoption("testrunuid")
@@ -49,7 +59,7 @@ def __init__(self, config, specs=None, defaultchdir="pyexecnetcache") -> None:
         self.group = execnet.Group()
         if specs is None:
             specs = self._getxspecs()
-        self.specs = []
+        self.specs: list[execnet.XSpec] = []
         for spec in specs:
             if not isinstance(spec, execnet.XSpec):
                 spec = execnet.XSpec(spec)
@@ -61,31 +71,39 @@ def __init__(self, config, specs=None, defaultchdir="pyexecnetcache") -> None:
         self.rsyncoptions = self._getrsyncoptions()
         self._rsynced_specs: set[tuple[Any, Any]] = set()
 
-    def rsync_roots(self, gateway):
+    def rsync_roots(self, gateway: execnet.Gateway) -> None:
         """Rsync the set of roots to the node's gateway cwd."""
         if self.roots:
             for root in self.roots:
                 self.rsync(gateway, root, **self.rsyncoptions)
 
-    def setup_nodes(self, putevent):
+    def setup_nodes(
+        self,
+        putevent: Callable[[tuple[str, dict[str, Any]]], None],
+    ) -> list[WorkerController]:
         self.config.hook.pytest_xdist_setupnodes(config=self.config, specs=self.specs)
         self.trace("setting up nodes")
         return [self.setup_node(spec, putevent) for spec in self.specs]
 
-    def setup_node(self, spec, putevent):
+    def setup_node(
+        self,
+        spec: execnet.XSpec,
+        putevent: Callable[[tuple[str, dict[str, Any]]], None],
+    ) -> WorkerController:
         gw = self.group.makegateway(spec)
         self.config.hook.pytest_xdist_newgateway(gateway=gw)
         self.rsync_roots(gw)
         node = WorkerController(self, gw, self.config, putevent)
-        gw.node = node  # keep the node alive
+        # Keep the node alive.
+        gw.node = node  # type: ignore[attr-defined]
         node.setup()
         self.trace("started node %r" % node)
         return node
 
-    def teardown_nodes(self):
+    def teardown_nodes(self) -> None:
         self.group.terminate(self.EXIT_TIMEOUT)
 
-    def _getxspecs(self):
+    def _getxspecs(self) -> list[execnet.XSpec]:
         return [execnet.XSpec(x) for x in parse_spec_config(self.config)]
 
     def _getrsyncdirs(self) -> list[Path]:
@@ -97,7 +115,7 @@ def _getrsyncdirs(self) -> list[Path]:
         import _pytest
         import pytest
 
-        def get_dir(p):
+        def get_dir(p: str) -> str:
             """Return the directory path if p is a package or the path to the .py file otherwise."""
             stripped = p.rstrip("co")
             if os.path.basename(stripped) == "__init__.py":
@@ -115,14 +133,14 @@ def get_dir(p):
             candidates.extend(rsyncroots)
         roots = []
         for root in candidates:
-            root = Path(root).resolve()
-            if not root.exists():
+            root_path = Path(root).resolve()
+            if not root_path.exists():
                 raise pytest.UsageError(f"rsyncdir doesn't exist: {root!r}")
-            if root not in roots:
-                roots.append(root)
+            if root_path not in roots:
+                roots.append(root_path)
         return roots
 
-    def _getrsyncoptions(self):
+    def _getrsyncoptions(self) -> dict[str, Any]:
         """Get options to be passed for rsync."""
         ignores = list(self.DEFAULT_IGNORES)
         ignores += [str(path) for path in self.config.option.rsyncignore]
@@ -133,7 +151,16 @@ def _getrsyncoptions(self):
             "verbose": getattr(self.config.option, "verbose", 0),
         }
 
-    def rsync(self, gateway, source, notify=None, verbose=False, ignores=None):
+    def rsync(
+        self,
+        gateway: execnet.Gateway,
+        source: str | os.PathLike[str],
+        notify: (
+            Callable[[str, execnet.XSpec, str | os.PathLike[str]], Any] | None
+        ) = None,
+        verbose: int = False,
+        ignores: Sequence[str] | None = None,
+    ) -> None:
         """Perform rsync to remote hosts for node."""
         # XXX This changes the calling behaviour of
         #     pytest_xdist_rsyncstart and pytest_xdist_rsyncfinish to
@@ -153,7 +180,7 @@ def rsync(self, gateway, source, notify=None, verbose=False, ignores=None):
         if (spec, source) in self._rsynced_specs:
             return
 
-        def finished():
+        def finished() -> None:
             if notify:
                 notify("rsyncrootready", spec, source)
 
@@ -189,11 +216,19 @@ def filter(self, path: PathLike) -> bool:
         else:
             return True
 
-    def add_target_host(self, gateway, finished=None):
+    def add_target_host(
+        self,
+        gateway: execnet.Gateway,
+        finished: Callable[[], None] | None = None,
+    ) -> None:
         remotepath = os.path.basename(self._sourcedir)
         super().add_target(gateway, remotepath, finishedcallback=finished, delete=True)
 
-    def _report_send_file(self, gateway, modified_rel_path):
+    def _report_send_file(
+        self,
+        gateway: execnet.Gateway,  # type: ignore[override]
+        modified_rel_path: str,
+    ) -> None:
         if self._verbose > 0:
             path = os.path.basename(self._sourcedir) + "/" + modified_rel_path
             remotepath = gateway.spec.chdir
@@ -234,12 +269,21 @@ class Marker(enum.Enum):
 
 
 class WorkerController:
+    # Set when the worker is ready.
+    workerinfo: WorkerInfo
+
     class RemoteHook:
         @pytest.hookimpl(trylast=True)
-        def pytest_xdist_getremotemodule(self):
+        def pytest_xdist_getremotemodule(self) -> Any:
             return xdist.remote
 
-    def __init__(self, nodemanager, gateway, config, putevent):
+    def __init__(
+        self,
+        nodemanager: NodeManager,
+        gateway: execnet.Gateway,
+        config: pytest.Config,
+        putevent: Callable[[tuple[str, dict[str, Any]]], None],
+    ) -> None:
         config.pluginmanager.register(self.RemoteHook())
         self.nodemanager = nodemanager
         self.putevent = putevent
@@ -255,14 +299,14 @@ def __init__(self, nodemanager, gateway, config, putevent):
         self._shutdown_sent = False
         self.log = Producer(f"workerctl-{gateway.id}", enabled=config.option.debug)
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return f"<{self.__class__.__name__} {self.gateway.id}>"
 
     @property
-    def shutting_down(self):
+    def shutting_down(self) -> bool:
         return self._down or self._shutdown_sent
 
-    def setup(self):
+    def setup(self) -> None:
         self.log("setting up worker session")
         spec = self.gateway.spec
         args = [str(x) for x in self.config.invocation_params.args or ()]
@@ -283,10 +327,11 @@ def setup(self):
         change_sys_path = _sys_path if self.gateway.spec.popen else None
         self.channel.send((self.workerinput, args, option_dict, change_sys_path))
 
-        if self.putevent:
+        # putevent is only None in a test.
+        if self.putevent:  # type: ignore[truthy-function]
             self.channel.setcallback(self.process_from_remote, endmarker=Marker.END)
 
-    def ensure_teardown(self):
+    def ensure_teardown(self) -> None:
         if hasattr(self, "channel"):
             if not self.channel.isclosed():
                 self.log("closing", self.channel)
@@ -297,16 +342,16 @@ def ensure_teardown(self):
             self.gateway.exit()
             # del self.gateway
 
-    def send_runtest_some(self, indices):
+    def send_runtest_some(self, indices: Sequence[int]) -> None:
         self.sendcommand("runtests", indices=indices)
 
-    def send_runtest_all(self):
+    def send_runtest_all(self) -> None:
         self.sendcommand("runtests_all")
 
-    def send_steal(self, indices):
+    def send_steal(self, indices: Sequence[int]) -> None:
         self.sendcommand("steal", indices=indices)
 
-    def shutdown(self):
+    def shutdown(self) -> None:
         if not self._down:
             try:
                 self.sendcommand("shutdown")
@@ -314,16 +359,18 @@ def shutdown(self):
                 pass
             self._shutdown_sent = True
 
-    def sendcommand(self, name, **kwargs):
+    def sendcommand(self, name: str, **kwargs: object) -> None:
         """Send a named parametrized command to the other side."""
         self.log(f"sending command {name}(**{kwargs})")
         self.channel.send((name, kwargs))
 
-    def notify_inproc(self, eventname, **kwargs):
+    def notify_inproc(self, eventname: str, **kwargs: object) -> None:
         self.log(f"queuing {eventname}(**{kwargs})")
         self.putevent((eventname, kwargs))
 
-    def process_from_remote(self, eventcall):
+    def process_from_remote(
+        self, eventcall: tuple[str, dict[str, Any]] | Literal[Marker.END]
+    ) -> None:
         """This gets called for each object we receive from
         the other side and if the channel closes.
 
@@ -333,7 +380,7 @@ def process_from_remote(self, eventcall):
         """
         try:
             if eventcall is Marker.END:
-                err = self.channel._getremoteerror()
+                err: object | None = self.channel._getremoteerror()  # type: ignore[no-untyped-call]
                 if not self._down:
                     if not err or isinstance(err, EOFError):
                         err = "Not properly terminated"  # lost connection?
@@ -399,9 +446,8 @@ def process_from_remote(self, eventcall):
             self.notify_inproc("errordown", node=self, error=excinfo)
 
 
-def unserialize_warning_message(data):
+def unserialize_warning_message(data: dict[str, Any]) -> warnings.WarningMessage:
     import importlib
-    import warnings
 
     if data["message_module"]:
         mod = importlib.import_module(data["message_module"])
@@ -438,4 +484,4 @@ def unserialize_warning_message(data):
             continue
         kwargs[attr_name] = data[attr_name]
 
-    return warnings.WarningMessage(**kwargs)  # type: ignore[arg-type]
+    return warnings.WarningMessage(**kwargs)
diff --git a/testing/acceptance_test.py b/testing/acceptance_test.py
index d17ddf09..3ef10cc9 100644
--- a/testing/acceptance_test.py
+++ b/testing/acceptance_test.py
@@ -3,6 +3,7 @@
 import os
 import re
 import shutil
+from typing import cast
 
 import pytest
 
@@ -223,7 +224,7 @@ def test_crash():
         assert result.ret == 1
 
     def test_distribution_rsyncdirs_example(
-        self, pytester: pytest.Pytester, monkeypatch
+        self, pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch
     ) -> None:
         # use a custom plugin that has a custom command-line option to ensure
         # this is propagated to workers (see #491)
@@ -415,7 +416,7 @@ def test_hello():
 
 class TestTerminalReporting:
     @pytest.mark.parametrize("verbosity", ["", "-q", "-v"])
-    def test_output_verbosity(self, pytester, verbosity: str) -> None:
+    def test_output_verbosity(self, pytester: pytest.Pytester, verbosity: str) -> None:
         pytester.makepyfile(
             """
             def test_ok():
@@ -610,7 +611,7 @@ def test_hello(myarg):
 
 
 def test_config_initialization(
-    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch, pytestconfig
+    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch
 ) -> None:
     """Ensure workers and controller are initialized consistently. Integration test for #445."""
     pytester.makepyfile(
@@ -635,7 +636,7 @@ def test_1(request):
 
 
 @pytest.mark.parametrize("when", ["setup", "call", "teardown"])
-def test_crashing_item(pytester, when) -> None:
+def test_crashing_item(pytester: pytest.Pytester, when: str) -> None:
     """Ensure crashing item is correctly reported during all testing stages."""
     code = dict(setup="", call="", teardown="")
     code[when] = "os._exit(1)"
@@ -766,7 +767,7 @@ def test_ok():
 
 
 @pytest.mark.parametrize("plugin", ["xdist.looponfail"])
-def test_sub_plugins_disabled(pytester, plugin) -> None:
+def test_sub_plugins_disabled(pytester: pytest.Pytester, plugin: str) -> None:
     """Test that xdist doesn't break if we disable any of its sub-plugins (#32)."""
     p1 = pytester.makepyfile(
         """
@@ -781,7 +782,7 @@ def test_ok():
 
 class TestWarnings:
     @pytest.mark.parametrize("n", ["-n0", "-n1"])
-    def test_warnings(self, pytester, n) -> None:
+    def test_warnings(self, pytester: pytest.Pytester, n: str) -> None:
         pytester.makepyfile(
             """
             import warnings, py, pytest
@@ -827,7 +828,7 @@ def test():
         result.stdout.no_fnmatch_line("*this hook should not be called in this version")
 
     @pytest.mark.parametrize("n", ["-n0", "-n1"])
-    def test_custom_subclass(self, pytester, n) -> None:
+    def test_custom_subclass(self, pytester: pytest.Pytester, n: str) -> None:
         """Check that warning subclasses that don't honor the args attribute don't break
         pytest-xdist (#344).
         """
@@ -851,7 +852,7 @@ def test_func(request):
         result.stdout.fnmatch_lines(["*MyWarning*", "*1 passed, 1 warning*"])
 
     @pytest.mark.parametrize("n", ["-n0", "-n1"])
-    def test_unserializable_arguments(self, pytester, n) -> None:
+    def test_unserializable_arguments(self, pytester: pytest.Pytester, n: str) -> None:
         """Check that warnings with unserializable arguments are handled correctly (#349)."""
         pytester.makepyfile(
             """
@@ -869,7 +870,9 @@ def test_func(tmp_path):
         result.stdout.fnmatch_lines(["*UserWarning*foo.txt*", "*1 passed, 1 warning*"])
 
     @pytest.mark.parametrize("n", ["-n0", "-n1"])
-    def test_unserializable_warning_details(self, pytester, n) -> None:
+    def test_unserializable_warning_details(
+        self, pytester: pytest.Pytester, n: str
+    ) -> None:
         """Check that warnings with unserializable _WARNING_DETAILS are
         handled correctly (#379).
         """
@@ -1049,7 +1052,7 @@ def test_c(): pass
 
 
 @pytest.mark.parametrize("n", [0, 2])
-def test_worker_id_fixture(pytester, n) -> None:
+def test_worker_id_fixture(pytester: pytest.Pytester, n: int) -> None:
     import glob
 
     f = pytester.makepyfile(
@@ -1065,8 +1068,8 @@ def test_worker_id1(worker_id, run_num):
     result.stdout.fnmatch_lines("* 2 passed in *")
     worker_ids = set()
     for fname in glob.glob(str(pytester.path / "*.txt")):
-        with open(fname) as f:
-            worker_ids.add(f.read().strip())
+        with open(fname) as fp:
+            worker_ids.add(fp.read().strip())
     if n == 0:
         assert worker_ids == {"master"}
     else:
@@ -1074,7 +1077,7 @@ def test_worker_id1(worker_id, run_num):
 
 
 @pytest.mark.parametrize("n", [0, 2])
-def test_testrun_uid_fixture(pytester, n) -> None:
+def test_testrun_uid_fixture(pytester: pytest.Pytester, n: int) -> None:
     import glob
 
     f = pytester.makepyfile(
@@ -1090,14 +1093,14 @@ def test_testrun_uid1(testrun_uid, run_num):
     result.stdout.fnmatch_lines("* 2 passed in *")
     testrun_uids = set()
     for fname in glob.glob(str(pytester.path / "*.txt")):
-        with open(fname) as f:
-            testrun_uids.add(f.read().strip())
+        with open(fname) as fp:
+            testrun_uids.add(fp.read().strip())
     assert len(testrun_uids) == 1
     assert len(testrun_uids.pop()) == 32
 
 
 @pytest.mark.parametrize("tb", ["auto", "long", "short", "no", "line", "native"])
-def test_error_report_styles(pytester, tb) -> None:
+def test_error_report_styles(pytester: pytest.Pytester, tb: str) -> None:
     pytester.makepyfile(
         """
         import pytest
@@ -1111,7 +1114,7 @@ def test_error_report_styles():
     result.assert_outcomes(failed=1)
 
 
-def test_color_yes_collection_on_non_atty(pytester) -> None:
+def test_color_yes_collection_on_non_atty(pytester: pytest.Pytester) -> None:
     """Skip collect progress report when working on non-terminals.
 
     Similar to pytest-dev/pytest#1397
@@ -1133,7 +1136,7 @@ def test_this(i):
     assert "collecting:" not in result.stdout.str()
 
 
-def test_without_terminal_plugin(pytester, request) -> None:
+def test_without_terminal_plugin(pytester: pytest.Pytester) -> None:
     """No output when terminal plugin is disabled."""
     pytester.makepyfile(
         """
@@ -1368,7 +1371,7 @@ def test_2():
 
 
 class TestGroupScope:
-    def test_by_module(self, pytester: pytest.Pytester):
+    def test_by_module(self, pytester: pytest.Pytester) -> None:
         test_file = """
             import pytest
             class TestA:
@@ -1399,7 +1402,7 @@ def test(self, i):
             == test_b_workers_and_test_count.items()
         )
 
-    def test_by_class(self, pytester: pytest.Pytester):
+    def test_by_class(self, pytester: pytest.Pytester) -> None:
         pytester.makepyfile(
             test_a="""
             import pytest
@@ -1436,7 +1439,7 @@ def test(self, i):
             == test_b_workers_and_test_count.items()
         )
 
-    def test_module_single_start(self, pytester: pytest.Pytester):
+    def test_module_single_start(self, pytester: pytest.Pytester) -> None:
         test_file1 = """
             import pytest
             @pytest.mark.xdist_group(name="xdist_group")
@@ -1459,7 +1462,7 @@ def test_2():
 
         assert a.keys() == b.keys() and b.keys() == c.keys()
 
-    def test_with_two_group_names(self, pytester: pytest.Pytester):
+    def test_with_two_group_names(self, pytester: pytest.Pytester) -> None:
         test_file = """
             import pytest
             @pytest.mark.xdist_group(name="group1")
@@ -1512,7 +1515,7 @@ def test_c(self):
     @pytest.mark.parametrize(
         "scope", ["each", "load", "loadscope", "loadfile", "worksteal", "no"]
     )
-    def test_single_file(self, pytester, scope) -> None:
+    def test_single_file(self, pytester: pytest.Pytester, scope: str) -> None:
         pytester.makepyfile(test_a=self.test_file1)
         result = pytester.runpytest("-n2", "--dist=%s" % scope, "-v")
         result.assert_outcomes(passed=(12 if scope != "each" else 12 * 2))
@@ -1520,7 +1523,7 @@ def test_single_file(self, pytester, scope) -> None:
     @pytest.mark.parametrize(
         "scope", ["each", "load", "loadscope", "loadfile", "worksteal", "no"]
     )
-    def test_multi_file(self, pytester, scope) -> None:
+    def test_multi_file(self, pytester: pytest.Pytester, scope: str) -> None:
         pytester.makepyfile(
             test_a=self.test_file1,
             test_b=self.test_file1,
@@ -1564,32 +1567,32 @@ def get_workers_and_test_count_by_prefix(
 
 class TestAPI:
     @pytest.fixture
-    def fake_request(self):
+    def fake_request(self) -> pytest.FixtureRequest:
         class FakeOption:
-            def __init__(self):
+            def __init__(self) -> None:
                 self.dist = "load"
 
         class FakeConfig:
-            def __init__(self):
+            def __init__(self) -> None:
                 self.workerinput = {"workerid": "gw5"}
                 self.option = FakeOption()
 
         class FakeRequest:
-            def __init__(self):
+            def __init__(self) -> None:
                 self.config = FakeConfig()
 
-        return FakeRequest()
+        return cast(pytest.FixtureRequest, FakeRequest())
 
-    def test_is_xdist_worker(self, fake_request) -> None:
+    def test_is_xdist_worker(self, fake_request: pytest.FixtureRequest) -> None:
         assert xdist.is_xdist_worker(fake_request)
-        del fake_request.config.workerinput
+        del fake_request.config.workerinput  # type: ignore[attr-defined]
         assert not xdist.is_xdist_worker(fake_request)
 
-    def test_is_xdist_controller(self, fake_request) -> None:
+    def test_is_xdist_controller(self, fake_request: pytest.FixtureRequest) -> None:
         assert not xdist.is_xdist_master(fake_request)
         assert not xdist.is_xdist_controller(fake_request)
 
-        del fake_request.config.workerinput
+        del fake_request.config.workerinput  # type: ignore[attr-defined]
         assert xdist.is_xdist_master(fake_request)
         assert xdist.is_xdist_controller(fake_request)
 
@@ -1597,13 +1600,13 @@ def test_is_xdist_controller(self, fake_request) -> None:
         assert not xdist.is_xdist_master(fake_request)
         assert not xdist.is_xdist_controller(fake_request)
 
-    def test_get_xdist_worker_id(self, fake_request) -> None:
+    def test_get_xdist_worker_id(self, fake_request: pytest.FixtureRequest) -> None:
         assert xdist.get_xdist_worker_id(fake_request) == "gw5"
-        del fake_request.config.workerinput
+        del fake_request.config.workerinput  # type: ignore[attr-defined]
         assert xdist.get_xdist_worker_id(fake_request) == "master"
 
 
-def test_collection_crash(pytester: pytest.Pytester):
+def test_collection_crash(pytester: pytest.Pytester) -> None:
     p1 = pytester.makepyfile(
         """
         assert 0
@@ -1622,7 +1625,7 @@ def test_collection_crash(pytester: pytest.Pytester):
     )
 
 
-def test_dist_in_addopts(pytester: pytest.Pytester):
+def test_dist_in_addopts(pytester: pytest.Pytester) -> None:
     """Users can set a default distribution in the configuration file (#789)."""
     pytester.makepyfile(
         """
diff --git a/testing/conftest.py b/testing/conftest.py
index 70bdfdff..5186b8b6 100644
--- a/testing/conftest.py
+++ b/testing/conftest.py
@@ -1,6 +1,8 @@
 from __future__ import annotations
 
 import shutil
+from typing import Callable
+from typing import Generator
 
 import execnet
 import pytest
@@ -10,12 +12,14 @@
 
 
 @pytest.fixture(autouse=True)
-def _divert_atexit(request, monkeypatch: pytest.MonkeyPatch):
+def _divert_atexit(monkeypatch: pytest.MonkeyPatch) -> Generator[None, None, None]:
     import atexit
 
     finalizers = []
 
-    def fake_register(func, *args, **kwargs):
+    def fake_register(
+        func: Callable[..., object], *args: object, **kwargs: object
+    ) -> None:
         finalizers.append((func, args, kwargs))
 
     monkeypatch.setattr(atexit, "register", fake_register)
@@ -27,7 +31,7 @@ def fake_register(func, *args, **kwargs):
         func(*args, **kwargs)
 
 
-def pytest_addoption(parser) -> None:
+def pytest_addoption(parser: pytest.Parser) -> None:
     parser.addoption(
         "--gx",
         action="append",
@@ -37,16 +41,16 @@ def pytest_addoption(parser) -> None:
 
 
 @pytest.fixture
-def specssh(request) -> str:
+def specssh(request: pytest.FixtureRequest) -> str:
     return getspecssh(request.config)
 
 
 # configuration information for tests
-def getgspecs(config) -> list[execnet.XSpec]:
+def getgspecs(config: pytest.Config) -> list[execnet.XSpec]:
     return [execnet.XSpec(spec) for spec in config.getvalueorskip("gspecs")]
 
 
-def getspecssh(config) -> str:  # type: ignore[return]
+def getspecssh(config: pytest.Config) -> str:
     xspecs = getgspecs(config)
     for spec in xspecs:
         if spec.ssh:
@@ -56,7 +60,7 @@ def getspecssh(config) -> str:  # type: ignore[return]
     pytest.skip("need '--gx ssh=...'")
 
 
-def getsocketspec(config) -> execnet.XSpec:
+def getsocketspec(config: pytest.Config) -> execnet.XSpec:
     xspecs = getgspecs(config)
     for spec in xspecs:
         if spec.socket:
diff --git a/testing/test_dsession.py b/testing/test_dsession.py
index 2a32a46e..e57caeb2 100644
--- a/testing/test_dsession.py
+++ b/testing/test_dsession.py
@@ -1,6 +1,9 @@
 from __future__ import annotations
 
+from typing import Any
+from typing import cast
 from typing import Sequence
+from typing import TYPE_CHECKING
 
 import execnet
 import pytest
@@ -13,29 +16,38 @@
 from xdist.scheduler import EachScheduling
 from xdist.scheduler import LoadScheduling
 from xdist.scheduler import WorkStealingScheduling
+from xdist.workermanage import WorkerController
 
 
-class MockGateway:
+if TYPE_CHECKING:
+    BaseOfMockGateway = execnet.Gateway
+    BaseOfMockNode = WorkerController
+else:
+    BaseOfMockGateway = object
+    BaseOfMockNode = object
+
+
+class MockGateway(BaseOfMockGateway):
     def __init__(self) -> None:
         self._count = 0
         self.id = str(self._count)
         self._count += 1
 
 
-class MockNode:
+class MockNode(BaseOfMockNode):
     def __init__(self) -> None:
-        self.sent = []  # type: ignore[var-annotated]
-        self.stolen = []  # type: ignore[var-annotated]
+        self.sent: list[int | str] = []
+        self.stolen: list[int] = []
         self.gateway = MockGateway()
         self._shutdown = False
 
-    def send_runtest_some(self, indices) -> None:
+    def send_runtest_some(self, indices: Sequence[int]) -> None:
         self.sent.extend(indices)
 
     def send_runtest_all(self) -> None:
         self.sent.append("ALL")
 
-    def send_steal(self, indices) -> None:
+    def send_steal(self, indices: Sequence[int]) -> None:
         self.stolen.extend(indices)
 
     def shutdown(self) -> None:
@@ -48,10 +60,9 @@ def shutting_down(self) -> bool:
 
 class TestEachScheduling:
     def test_schedule_load_simple(self, pytester: pytest.Pytester) -> None:
-        node1 = MockNode()
-        node2 = MockNode()
         config = pytester.parseconfig("--tx=2*popen")
         sched = EachScheduling(config)
+        node1, node2 = MockNode(), MockNode()
         sched.add_node(node1)
         sched.add_node(node2)
         collection = ["a.py::test_1"]
@@ -59,7 +70,7 @@ def test_schedule_load_simple(self, pytester: pytest.Pytester) -> None:
         sched.add_node_collection(node1, collection)
         assert not sched.collection_is_completed
         sched.add_node_collection(node2, collection)
-        assert sched.collection_is_completed
+        assert bool(sched.collection_is_completed)
         assert sched.node2collection[node1] == collection
         assert sched.node2collection[node2] == collection
         sched.schedule()
@@ -72,14 +83,14 @@ def test_schedule_load_simple(self, pytester: pytest.Pytester) -> None:
         assert sched.tests_finished
 
     def test_schedule_remove_node(self, pytester: pytest.Pytester) -> None:
-        node1 = MockNode()
         config = pytester.parseconfig("--tx=popen")
         sched = EachScheduling(config)
+        node1 = MockNode()
         sched.add_node(node1)
         collection = ["a.py::test_1"]
         assert not sched.collection_is_completed
         sched.add_node_collection(node1, collection)
-        assert sched.collection_is_completed
+        assert bool(sched.collection_is_completed)
         assert sched.node2collection[node1] == collection
         sched.schedule()
         assert sched.tests_finished
@@ -93,15 +104,15 @@ class TestLoadScheduling:
     def test_schedule_load_simple(self, pytester: pytest.Pytester) -> None:
         config = pytester.parseconfig("--tx=2*popen")
         sched = LoadScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2 = sched.nodes
+        node1, node2 = MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
         collection = ["a.py::test_1", "a.py::test_2"]
         assert not sched.collection_is_completed
         sched.add_node_collection(node1, collection)
         assert not sched.collection_is_completed
         sched.add_node_collection(node2, collection)
-        assert sched.collection_is_completed
+        assert bool(sched.collection_is_completed)
         assert sched.node2collection[node1] == collection
         assert sched.node2collection[node2] == collection
         sched.schedule()
@@ -111,15 +122,17 @@ def test_schedule_load_simple(self, pytester: pytest.Pytester) -> None:
         assert len(node2.sent) == 1
         assert node1.sent == [0]
         assert node2.sent == [1]
-        sched.mark_test_complete(node1, node1.sent[0])
+        sent10 = node1.sent[0]
+        assert isinstance(sent10, int)
+        sched.mark_test_complete(node1, sent10)
         assert sched.tests_finished
 
     def test_schedule_batch_size(self, pytester: pytest.Pytester) -> None:
         config = pytester.parseconfig("--tx=2*popen")
         sched = LoadScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2 = sched.nodes
+        node1, node2 = MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
         col = ["xyz"] * 6
         sched.add_node_collection(node1, col)
         sched.add_node_collection(node2, col)
@@ -144,9 +157,9 @@ def test_schedule_batch_size(self, pytester: pytest.Pytester) -> None:
     def test_schedule_maxchunk_none(self, pytester: pytest.Pytester) -> None:
         config = pytester.parseconfig("--tx=2*popen")
         sched = LoadScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2 = sched.nodes
+        node1, node2 = MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
         col = [f"test{i}" for i in range(16)]
         sched.add_node_collection(node1, col)
         sched.add_node_collection(node2, col)
@@ -172,9 +185,9 @@ def test_schedule_maxchunk_none(self, pytester: pytest.Pytester) -> None:
     def test_schedule_maxchunk_1(self, pytester: pytest.Pytester) -> None:
         config = pytester.parseconfig("--tx=2*popen", "--maxschedchunk=1")
         sched = LoadScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2 = sched.nodes
+        node1, node2 = MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
         col = [f"test{i}" for i in range(16)]
         sched.add_node_collection(node1, col)
         sched.add_node_collection(node2, col)
@@ -186,7 +199,9 @@ def test_schedule_maxchunk_1(self, pytester: pytest.Pytester) -> None:
         assert sched.node2pending[node2] == node2.sent
 
         for complete_index, first_pending in enumerate(range(5, 16)):
-            sched.mark_test_complete(node1, node1.sent[complete_index])
+            sent_index = node1.sent[complete_index]
+            assert isinstance(sent_index, int)
+            sched.mark_test_complete(node1, sent_index)
             assert node1.sent == [0, 1, *range(4, first_pending)]
             assert node2.sent == [2, 3]
             assert sched.pending == list(range(first_pending, 16))
@@ -194,10 +209,10 @@ def test_schedule_maxchunk_1(self, pytester: pytest.Pytester) -> None:
     def test_schedule_fewer_tests_than_nodes(self, pytester: pytest.Pytester) -> None:
         config = pytester.parseconfig("--tx=3*popen")
         sched = LoadScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2, node3 = sched.nodes
+        node1, node2, node3 = MockNode(), MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
+        sched.add_node(node3)
         col = ["xyz"] * 2
         sched.add_node_collection(node1, col)
         sched.add_node_collection(node2, col)
@@ -215,10 +230,10 @@ def test_schedule_fewer_than_two_tests_per_node(
     ) -> None:
         config = pytester.parseconfig("--tx=3*popen")
         sched = LoadScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2, node3 = sched.nodes
+        node1, node2, node3 = MockNode(), MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
+        sched.add_node(node3)
         col = ["xyz"] * 5
         sched.add_node_collection(node1, col)
         sched.add_node_collection(node2, col)
@@ -232,9 +247,9 @@ def test_schedule_fewer_than_two_tests_per_node(
         assert not sched.pending
 
     def test_add_remove_node(self, pytester: pytest.Pytester) -> None:
-        node = MockNode()
         config = pytester.parseconfig("--tx=popen")
         sched = LoadScheduling(config)
+        node = MockNode()
         sched.add_node(node)
         collection = ["test_file.py::test_func"]
         sched.add_node_collection(node, collection)
@@ -253,18 +268,17 @@ def test_different_tests_collected(self, pytester: pytest.Pytester) -> None:
         class CollectHook:
             """Dummy hook that stores collection reports."""
 
-            def __init__(self):
-                self.reports = []
+            def __init__(self) -> None:
+                self.reports: list[pytest.CollectReport] = []
 
-            def pytest_collectreport(self, report):
+            def pytest_collectreport(self, report: pytest.CollectReport) -> None:
                 self.reports.append(report)
 
         collect_hook = CollectHook()
         config = pytester.parseconfig("--tx=2*popen")
         config.pluginmanager.register(collect_hook, "collect_hook")
-        node1 = MockNode()
-        node2 = MockNode()
         sched = LoadScheduling(config)
+        node1, node2 = MockNode(), MockNode()
         sched.add_node(node1)
         sched.add_node(node2)
         sched.add_node_collection(node1, ["a.py::test_1"])
@@ -272,6 +286,7 @@ def pytest_collectreport(self, report):
         sched.schedule()
         assert len(collect_hook.reports) == 1
         rep = collect_hook.reports[0]
+        assert isinstance(rep.longrepr, str)
         assert "Different tests were collected between" in rep.longrepr
 
 
@@ -279,15 +294,15 @@ class TestWorkStealingScheduling:
     def test_ideal_case(self, pytester: pytest.Pytester) -> None:
         config = pytester.parseconfig("--tx=2*popen")
         sched = WorkStealingScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2 = sched.nodes
+        node1, node2 = MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
         collection = [f"test_workstealing.py::test_{i}" for i in range(16)]
         assert not sched.collection_is_completed
         sched.add_node_collection(node1, collection)
         assert not sched.collection_is_completed
         sched.add_node_collection(node2, collection)
-        assert sched.collection_is_completed
+        assert bool(sched.collection_is_completed)
         assert sched.node2collection[node1] == collection
         assert sched.node2collection[node2] == collection
         sched.schedule()
@@ -296,18 +311,20 @@ def test_ideal_case(self, pytester: pytest.Pytester) -> None:
         assert node1.sent == list(range(8))
         assert node2.sent == list(range(8, 16))
         for i in range(8):
-            sched.mark_test_complete(node1, node1.sent[i])
-            sched.mark_test_complete(node2, node2.sent[i])
-        assert sched.tests_finished
+            sent1, sent2 = node1.sent[i], node2.sent[i]
+            assert isinstance(sent1, int) and isinstance(sent2, int)
+            sched.mark_test_complete(node1, sent1)
+            sched.mark_test_complete(node2, sent2)
+        assert bool(sched.tests_finished)
         assert node1.stolen == []
         assert node2.stolen == []
 
     def test_stealing(self, pytester: pytest.Pytester) -> None:
         config = pytester.parseconfig("--tx=2*popen")
         sched = WorkStealingScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2 = sched.nodes
+        node1, node2 = MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
         collection = [f"test_workstealing.py::test_{i}" for i in range(16)]
         sched.add_node_collection(node1, collection)
         sched.add_node_collection(node2, collection)
@@ -316,11 +333,15 @@ def test_stealing(self, pytester: pytest.Pytester) -> None:
         assert node1.sent == list(range(8))
         assert node2.sent == list(range(8, 16))
         for i in range(8):
-            sched.mark_test_complete(node1, node1.sent[i])
+            sent = node1.sent[i]
+            assert isinstance(sent, int)
+            sched.mark_test_complete(node1, sent)
         assert node2.stolen == list(range(12, 16))
         sched.remove_pending_tests_from_node(node2, node2.stolen)
         for i in range(4):
-            sched.mark_test_complete(node2, node2.sent[i])
+            sent = node2.sent[i]
+            assert isinstance(sent, int)
+            sched.mark_test_complete(node2, sent)
         assert node1.stolen == [14, 15]
         sched.remove_pending_tests_from_node(node1, node1.stolen)
         sched.mark_test_complete(node1, 12)
@@ -355,10 +376,10 @@ def test_steal_on_add_node(self, pytester: pytest.Pytester) -> None:
     def test_schedule_fewer_tests_than_nodes(self, pytester: pytest.Pytester) -> None:
         config = pytester.parseconfig("--tx=3*popen")
         sched = WorkStealingScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2, node3 = sched.nodes
+        node1, node2, node3 = MockNode(), MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
+        sched.add_node(node3)
         col = ["xyz"] * 2
         sched.add_node_collection(node1, col)
         sched.add_node_collection(node2, col)
@@ -378,10 +399,10 @@ def test_schedule_fewer_than_two_tests_per_node(
     ) -> None:
         config = pytester.parseconfig("--tx=3*popen")
         sched = WorkStealingScheduling(config)
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        sched.add_node(MockNode())
-        node1, node2, node3 = sched.nodes
+        node1, node2, node3 = MockNode(), MockNode(), MockNode()
+        sched.add_node(node1)
+        sched.add_node(node2)
+        sched.add_node(node3)
         col = ["xyz"] * 5
         sched.add_node_collection(node1, col)
         sched.add_node_collection(node2, col)
@@ -392,11 +413,19 @@ def test_schedule_fewer_than_two_tests_per_node(
         assert node3.sent == [3, 4]
         assert not sched.pending
         assert not sched.tests_finished
-        sched.mark_test_complete(node1, node1.sent[0])
-        sched.mark_test_complete(node2, node2.sent[0])
-        sched.mark_test_complete(node3, node3.sent[0])
-        sched.mark_test_complete(node3, node3.sent[1])
-        assert sched.tests_finished
+        sent10 = node1.sent[0]
+        assert isinstance(sent10, int)
+        sent20 = node2.sent[0]
+        assert isinstance(sent20, int)
+        sent30 = node3.sent[0]
+        assert isinstance(sent30, int)
+        sent31 = node3.sent[1]
+        assert isinstance(sent31, int)
+        sched.mark_test_complete(node1, sent10)
+        sched.mark_test_complete(node2, sent20)
+        sched.mark_test_complete(node3, sent30)
+        sched.mark_test_complete(node3, sent31)
+        assert bool(sched.tests_finished)
         assert node1.stolen == []
         assert node2.stolen == []
         assert node3.stolen == []
@@ -416,18 +445,17 @@ def test_add_remove_node(self, pytester: pytest.Pytester) -> None:
 
     def test_different_tests_collected(self, pytester: pytest.Pytester) -> None:
         class CollectHook:
-            def __init__(self):
-                self.reports = []
+            def __init__(self) -> None:
+                self.reports: list[pytest.CollectReport] = []
 
-            def pytest_collectreport(self, report):
+            def pytest_collectreport(self, report: pytest.CollectReport) -> None:
                 self.reports.append(report)
 
         collect_hook = CollectHook()
         config = pytester.parseconfig("--tx=2*popen")
         config.pluginmanager.register(collect_hook, "collect_hook")
-        node1 = MockNode()
-        node2 = MockNode()
         sched = WorkStealingScheduling(config)
+        node1, node2 = MockNode(), MockNode()
         sched.add_node(node1)
         sched.add_node(node2)
         sched.add_node_collection(node1, ["a.py::test_1"])
@@ -435,12 +463,13 @@ def pytest_collectreport(self, report):
         sched.schedule()
         assert len(collect_hook.reports) == 1
         rep = collect_hook.reports[0]
+        assert isinstance(rep.longrepr, str)
         assert "Different tests were collected between" in rep.longrepr
 
 
 class TestDistReporter:
     @pytest.mark.xfail
-    def test_rsync_printing(self, pytester: pytest.Pytester, linecomp) -> None:
+    def test_rsync_printing(self, pytester: pytest.Pytester, linecomp: Any) -> None:
         config = pytester.parseconfig()
         from _pytest.terminal import TerminalReporter
 
@@ -473,15 +502,17 @@ class gw2:
 def test_report_collection_diff_equal() -> None:
     """Test reporting of equal collections."""
     from_collection = to_collection = ["aaa", "bbb", "ccc"]
-    assert report_collection_diff(from_collection, to_collection, 1, 2) is None
+    assert report_collection_diff(from_collection, to_collection, "1", "2") is None
 
 
 def test_default_max_worker_restart() -> None:
-    class config:
+    class MockConfig:
         class option:
             maxworkerrestart: str | None = None
             numprocesses: int = 0
 
+    config = cast(pytest.Config, MockConfig)
+
     assert get_default_max_worker_restart(config) is None
 
     config.option.numprocesses = 2
diff --git a/testing/test_looponfail.py b/testing/test_looponfail.py
index e2fa02d7..eda0ad12 100644
--- a/testing/test_looponfail.py
+++ b/testing/test_looponfail.py
@@ -143,7 +143,7 @@ def test_func():
         control = RemoteControl(modcol.config)
         control.loop_once()
         assert control.failures
-        modcol_path = modcol.path  # type:ignore[attr-defined]
+        modcol_path = modcol.path
 
         modcol_path.write_text(
             textwrap.dedent(
@@ -173,7 +173,7 @@ def test_func():
                 """
             )
         )
-        parent = modcol.path.parent.parent  # type: ignore[attr-defined]
+        parent = modcol.path.parent.parent
         monkeypatch.chdir(parent)
         modcol.config.args = [
             str(Path(x).relative_to(parent)) for x in modcol.config.args
@@ -332,7 +332,7 @@ def test_one():
         remotecontrol = RemoteControl(modcol.config)
         orig_runsession = remotecontrol.runsession
 
-        def runsession_dups():
+        def runsession_dups() -> tuple[list[str], list[str], bool]:
             # twisted.trial test cases may report multiple errors.
             failures, reports, collection_failed = orig_runsession()
             print(failures)
diff --git a/testing/test_plugin.py b/testing/test_plugin.py
index 687a3d7f..f3526670 100644
--- a/testing/test_plugin.py
+++ b/testing/test_plugin.py
@@ -10,7 +10,7 @@
 
 
 @pytest.fixture
-def monkeypatch_3_cpus(monkeypatch: pytest.MonkeyPatch):
+def monkeypatch_3_cpus(monkeypatch: pytest.MonkeyPatch) -> None:
     """Make pytest-xdist believe the system has 3 CPUs."""
     # block import
     monkeypatch.setitem(sys.modules, "psutil", None)
@@ -128,7 +128,7 @@ def test_auto_detect_cpus_psutil(
 
 
 def test_auto_detect_cpus_os(
-    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch, monkeypatch_3_cpus
+    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch, monkeypatch_3_cpus: None
 ) -> None:
     from xdist.plugin import pytest_cmdline_main as check_options
 
@@ -189,7 +189,7 @@ def pytest_xdist_auto_num_workers(config):
 
 
 def test_hook_auto_num_workers_none(
-    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch, monkeypatch_3_cpus
+    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch, monkeypatch_3_cpus: None
 ) -> None:
     # Returning None from a hook to skip it is pytest behavior,
     # but we document it so let's test it.
@@ -231,7 +231,7 @@ def test_envvar_auto_num_workers(
 
 
 def test_envvar_auto_num_workers_warn(
-    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch, monkeypatch_3_cpus
+    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch, monkeypatch_3_cpus: None
 ) -> None:
     from xdist.plugin import pytest_cmdline_main as check_options
 
@@ -244,7 +244,7 @@ def test_envvar_auto_num_workers_warn(
 
 
 def test_auto_num_workers_hook_overrides_envvar(
-    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch, monkeypatch_3_cpus
+    pytester: pytest.Pytester, monkeypatch: pytest.MonkeyPatch, monkeypatch_3_cpus: None
 ) -> None:
     from xdist.plugin import pytest_cmdline_main as check_options
 
diff --git a/testing/test_remote.py b/testing/test_remote.py
index 245f27d0..c5726030 100644
--- a/testing/test_remote.py
+++ b/testing/test_remote.py
@@ -1,36 +1,44 @@
+from __future__ import annotations
+
 import marshal
 import pprint
 from queue import Queue
 import sys
+from typing import Any
+from typing import Callable
+from typing import cast
 import uuid
 
 import execnet
 import pytest
 
+from xdist.workermanage import NodeManager
 from xdist.workermanage import WorkerController
 
 
 WAIT_TIMEOUT = 10.0
 
 
-def check_marshallable(d):
+def check_marshallable(d: object) -> None:
     try:
-        marshal.dumps(d)
+        marshal.dumps(d)  # type: ignore[arg-type]
     except ValueError as e:
         pprint.pprint(d)
         raise ValueError("not marshallable") from e
 
 
 class EventCall:
-    def __init__(self, eventcall):
+    def __init__(self, eventcall: tuple[str, dict[str, Any]]) -> None:
         self.name, self.kwargs = eventcall
 
-    def __str__(self):
+    def __str__(self) -> str:
         return f"<EventCall {self.name}(**{self.kwargs})>"
 
 
 class WorkerSetup:
-    def __init__(self, request, pytester: pytest.Pytester) -> None:
+    def __init__(
+        self, request: pytest.FixtureRequest, pytester: pytest.Pytester
+    ) -> None:
         self.request = request
         self.pytester = pytester
         self.use_callback = False
@@ -47,11 +55,18 @@ class DummyMananger:
             testrunuid = uuid.uuid4().hex
             specs = [0, 1]
 
-        self.slp = WorkerController(DummyMananger, self.gateway, config, putevent)
+        nodemanager = cast(NodeManager, DummyMananger)
+
+        self.slp = WorkerController(
+            nodemanager=nodemanager,
+            gateway=self.gateway,
+            config=config,
+            putevent=putevent,  # type: ignore[arg-type]
+        )
         self.request.addfinalizer(self.slp.ensure_teardown)
         self.slp.setup()
 
-    def popevent(self, name=None):
+    def popevent(self, name: str | None = None) -> EventCall:
         while 1:
             if self.use_callback:
                 data = self.events.get(timeout=WAIT_TIMEOUT)
@@ -62,27 +77,33 @@ def popevent(self, name=None):
                 return ev
             print(f"skipping {ev}")
 
-    def sendcommand(self, name, **kwargs):
+    def sendcommand(self, name: str, **kwargs: Any) -> None:
         self.slp.sendcommand(name, **kwargs)
 
 
 @pytest.fixture
-def worker(request, pytester: pytest.Pytester) -> WorkerSetup:
+def worker(request: pytest.FixtureRequest, pytester: pytest.Pytester) -> WorkerSetup:
     return WorkerSetup(request, pytester)
 
 
 class TestWorkerInteractor:
+    UnserializerReport = Callable[
+        [dict[str, Any]], pytest.CollectReport | pytest.TestReport
+    ]
+
     @pytest.fixture
-    def unserialize_report(self, pytestconfig):
-        def unserialize(data):
-            return pytestconfig.hook.pytest_report_from_serializable(
+    def unserialize_report(self, pytestconfig: pytest.Config) -> UnserializerReport:
+        def unserialize(
+            data: dict[str, Any],
+        ) -> pytest.CollectReport | pytest.TestReport:
+            return pytestconfig.hook.pytest_report_from_serializable(  # type: ignore[no-any-return]
                 config=pytestconfig, data=data
             )
 
         return unserialize
 
     def test_basic_collect_and_runtests(
-        self, worker: WorkerSetup, unserialize_report
+        self, worker: WorkerSetup, unserialize_report: UnserializerReport
     ) -> None:
         worker.pytester.makepyfile(
             """
@@ -115,7 +136,9 @@ def test_func():
         ev = worker.popevent("workerfinished")
         assert "workeroutput" in ev.kwargs
 
-    def test_remote_collect_skip(self, worker: WorkerSetup, unserialize_report) -> None:
+    def test_remote_collect_skip(
+        self, worker: WorkerSetup, unserialize_report: UnserializerReport
+    ) -> None:
         worker.pytester.makepyfile(
             """
             import pytest
@@ -129,11 +152,14 @@ def test_remote_collect_skip(self, worker: WorkerSetup, unserialize_report) -> N
         assert ev.name == "collectreport"
         rep = unserialize_report(ev.kwargs["data"])
         assert rep.skipped
+        assert isinstance(rep.longrepr, tuple)
         assert rep.longrepr[2] == "Skipped: hello"
         ev = worker.popevent("collectionfinish")
         assert not ev.kwargs["ids"]
 
-    def test_remote_collect_fail(self, worker: WorkerSetup, unserialize_report) -> None:
+    def test_remote_collect_fail(
+        self, worker: WorkerSetup, unserialize_report: UnserializerReport
+    ) -> None:
         worker.pytester.makepyfile("""aasd qwe""")
         worker.setup()
         ev = worker.popevent("collectionstart")
@@ -145,7 +171,9 @@ def test_remote_collect_fail(self, worker: WorkerSetup, unserialize_report) -> N
         ev = worker.popevent("collectionfinish")
         assert not ev.kwargs["ids"]
 
-    def test_runtests_all(self, worker: WorkerSetup, unserialize_report) -> None:
+    def test_runtests_all(
+        self, worker: WorkerSetup, unserialize_report: UnserializerReport
+    ) -> None:
         worker.pytester.makepyfile(
             """
             def test_func(): pass
@@ -205,13 +233,15 @@ def test_process_from_remote_error_handling(
     ) -> None:
         worker.use_callback = True
         worker.setup()
-        worker.slp.process_from_remote(("<nonono>", ()))
+        worker.slp.process_from_remote(("<nonono>", {}))
         out, err = capsys.readouterr()
         assert "INTERNALERROR> ValueError: unknown event: <nonono>" in out
         ev = worker.popevent()
         assert ev.name == "errordown"
 
-    def test_steal_work(self, worker: WorkerSetup, unserialize_report) -> None:
+    def test_steal_work(
+        self, worker: WorkerSetup, unserialize_report: UnserializerReport
+    ) -> None:
         worker.pytester.makepyfile(
             """
             import time
@@ -262,7 +292,9 @@ def test_func4(): pass
         ev = worker.popevent("workerfinished")
         assert "workeroutput" in ev.kwargs
 
-    def test_steal_empty_queue(self, worker: WorkerSetup, unserialize_report) -> None:
+    def test_steal_empty_queue(
+        self, worker: WorkerSetup, unserialize_report: UnserializerReport
+    ) -> None:
         worker.pytester.makepyfile(
             """
             def test_func(): pass
diff --git a/testing/test_workermanage.py b/testing/test_workermanage.py
index 1246911f..08b38851 100644
--- a/testing/test_workermanage.py
+++ b/testing/test_workermanage.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from pathlib import Path
 import shutil
 import textwrap
@@ -19,13 +21,15 @@
 
 
 @pytest.fixture
-def hookrecorder(request, config, pytester: pytest.Pytester):
+def hookrecorder(
+    config: pytest.Config, pytester: pytest.Pytester
+) -> pytest.HookRecorder:
     hookrecorder = pytester.make_hook_recorder(config.pluginmanager)
     return hookrecorder
 
 
 @pytest.fixture
-def config(pytester: pytest.Pytester):
+def config(pytester: pytest.Pytester) -> pytest.Config:
     return pytester.parseconfig()
 
 
@@ -44,24 +48,23 @@ def dest(tmp_path: Path) -> Path:
 
 
 @pytest.fixture
-def workercontroller(monkeypatch: pytest.MonkeyPatch):
+def workercontroller(monkeypatch: pytest.MonkeyPatch) -> None:
     class MockController:
-        def __init__(self, *args):
+        def __init__(self, *args: object) -> None:
             pass
 
-        def setup(self):
+        def setup(self) -> None:
             pass
 
     monkeypatch.setattr(workermanage, "WorkerController", MockController)
-    return MockController
 
 
 class TestNodeManagerPopen:
-    def test_popen_no_default_chdir(self, config) -> None:
+    def test_popen_no_default_chdir(self, config: pytest.Config) -> None:
         gm = NodeManager(config, ["popen"])
         assert gm.specs[0].chdir is None
 
-    def test_default_chdir(self, config) -> None:
+    def test_default_chdir(self, config: pytest.Config) -> None:
         specs = ["ssh=noco", "socket=xyz"]
         for spec in NodeManager(config, specs).specs:
             assert spec.chdir == "pyexecnetcache"
@@ -69,10 +72,13 @@ def test_default_chdir(self, config) -> None:
             assert spec.chdir == "abc"
 
     def test_popen_makegateway_events(
-        self, config, hookrecorder, workercontroller
+        self,
+        config: pytest.Config,
+        hookrecorder: pytest.HookRecorder,
+        workercontroller: None,
     ) -> None:
         hm = NodeManager(config, ["popen"] * 2)
-        hm.setup_nodes(None)
+        hm.setup_nodes(None)  # type: ignore[arg-type]
         call = hookrecorder.popcall("pytest_xdist_setupnodes")
         assert len(call.specs) == 2
 
@@ -86,20 +92,24 @@ def test_popen_makegateway_events(
         assert not len(hm.group)
 
     def test_popens_rsync(
-        self, config, source: Path, dest: Path, workercontroller
+        self,
+        config: pytest.Config,
+        source: Path,
+        dest: Path,
+        workercontroller: None,
     ) -> None:
         hm = NodeManager(config, ["popen"] * 2)
-        hm.setup_nodes(None)
+        hm.setup_nodes(None)  # type: ignore[arg-type]
         assert len(hm.group) == 2
         for gw in hm.group:
 
             class pseudoexec:
                 args = []  # type: ignore[var-annotated]
 
-                def __init__(self, *args):
+                def __init__(self, *args: object) -> None:
                     self.args.extend(args)
 
-                def waitclose(self):
+                def waitclose(self) -> None:
                     pass
 
             gw.remote_exec = pseudoexec  # type: ignore[assignment]
@@ -112,10 +122,10 @@ def waitclose(self):
         assert "sys.path.insert" in gw.remote_exec.args[0]  # type: ignore[attr-defined]
 
     def test_rsync_popen_with_path(
-        self, config, source: Path, dest: Path, workercontroller
+        self, config: pytest.Config, source: Path, dest: Path, workercontroller: None
     ) -> None:
         hm = NodeManager(config, ["popen//chdir=%s" % dest] * 1)
-        hm.setup_nodes(None)
+        hm.setup_nodes(None)  # type: ignore[arg-type]
         source.joinpath("dir1", "dir2").mkdir(parents=True)
         source.joinpath("dir1", "dir2", "hello").touch()
         notifications = []
@@ -131,15 +141,15 @@ def test_rsync_popen_with_path(
 
     def test_rsync_same_popen_twice(
         self,
-        config,
+        config: pytest.Config,
         source: Path,
         dest: Path,
-        hookrecorder,
-        workercontroller,
+        hookrecorder: pytest.HookRecorder,
+        workercontroller: None,
     ) -> None:
         hm = NodeManager(config, ["popen//chdir=%s" % dest] * 2)
         hm.roots = []
-        hm.setup_nodes(None)
+        hm.setup_nodes(None)  # type: ignore[arg-type]
         source.joinpath("dir1", "dir2").mkdir(parents=True)
         source.joinpath("dir1", "dir2", "hello").touch()
         gw = hm.group[0]
@@ -200,7 +210,11 @@ def test_rsync_roots_no_roots(
         assert p.joinpath("dir1", "file1").check()
 
     def test_popen_rsync_subdir(
-        self, pytester: pytest.Pytester, source: Path, dest: Path, workercontroller
+        self,
+        pytester: pytest.Pytester,
+        source: Path,
+        dest: Path,
+        workercontroller: None,
     ) -> None:
         dir1 = source / "dir1"
         dir1.mkdir()
@@ -214,7 +228,8 @@ def test_popen_rsync_subdir(
                     "--tx", "popen//chdir=%s" % dest, "--rsyncdir", rsyncroot, source
                 )
             )
-            nodemanager.setup_nodes(None)  # calls .rsync_roots()
+            # calls .rsync_roots()
+            nodemanager.setup_nodes(None)  # type: ignore[arg-type]
             if rsyncroot == source:
                 dest = dest.joinpath("source")
             assert dest.joinpath("dir1").exists()
@@ -223,14 +238,19 @@ def test_popen_rsync_subdir(
             nodemanager.teardown_nodes()
 
     @pytest.mark.parametrize(
-        "flag, expects_report", [("-q", False), ("", False), ("-v", True)]
+        ["flag", "expects_report"],
+        [
+            ("-q", False),
+            ("", False),
+            ("-v", True),
+        ],
     )
     def test_rsync_report(
         self,
         pytester: pytest.Pytester,
         source: Path,
         dest: Path,
-        workercontroller,
+        workercontroller: None,
         capsys: pytest.CaptureFixture[str],
         flag: str,
         expects_report: bool,
@@ -241,7 +261,8 @@ def test_rsync_report(
         if flag:
             args.append(flag)
         nodemanager = NodeManager(pytester.parseconfig(*args))
-        nodemanager.setup_nodes(None)  # calls .rsync_roots()
+        # calls .rsync_roots()
+        nodemanager.setup_nodes(None)  # type: ignore[arg-type]
         out, _ = capsys.readouterr()
         if expects_report:
             assert "<= pytest/__init__.py" in out
@@ -249,7 +270,11 @@ def test_rsync_report(
             assert "<= pytest/__init__.py" not in out
 
     def test_init_rsync_roots(
-        self, pytester: pytest.Pytester, source: Path, dest: Path, workercontroller
+        self,
+        pytester: pytest.Pytester,
+        source: Path,
+        dest: Path,
+        workercontroller: None,
     ) -> None:
         dir2 = source.joinpath("dir1", "dir2")
         dir2.mkdir(parents=True)
@@ -267,13 +292,18 @@ def test_init_rsync_roots(
         )
         config = pytester.parseconfig(source)
         nodemanager = NodeManager(config, ["popen//chdir=%s" % dest])
-        nodemanager.setup_nodes(None)  # calls .rsync_roots()
+        # calls .rsync_roots()
+        nodemanager.setup_nodes(None)  # type: ignore[arg-type]
         assert dest.joinpath("dir2").exists()
         assert not dest.joinpath("dir1").exists()
         assert not dest.joinpath("bogus").exists()
 
     def test_rsyncignore(
-        self, pytester: pytest.Pytester, source: Path, dest: Path, workercontroller
+        self,
+        pytester: pytest.Pytester,
+        source: Path,
+        dest: Path,
+        workercontroller: None,
     ) -> None:
         dir2 = source.joinpath("dir1", "dir2")
         dir2.mkdir(parents=True)
@@ -297,7 +327,8 @@ def test_rsyncignore(
         config = pytester.parseconfig(source)
         config.option.rsyncignore = ["bar"]
         nodemanager = NodeManager(config, ["popen//chdir=%s" % dest])
-        nodemanager.setup_nodes(None)  # calls .rsync_roots()
+        # calls .rsync_roots()
+        nodemanager.setup_nodes(None)  # type: ignore[arg-type]
         assert dest.joinpath("dir1").exists()
         assert not dest.joinpath("dir1", "dir2").exists()
         assert dest.joinpath("dir5", "file").exists()
@@ -306,14 +337,19 @@ def test_rsyncignore(
         assert not dest.joinpath("bar").exists()
 
     def test_optimise_popen(
-        self, pytester: pytest.Pytester, source: Path, dest: Path, workercontroller
+        self,
+        pytester: pytest.Pytester,
+        source: Path,
+        dest: Path,
+        workercontroller: None,
     ) -> None:
         specs = ["popen"] * 3
         source.joinpath("conftest.py").write_text("rsyncdirs = ['a']")
         source.joinpath("a").mkdir()
         config = pytester.parseconfig(source)
         nodemanager = NodeManager(config, specs)
-        nodemanager.setup_nodes(None)  # calls .rysnc_roots()
+        # calls .rysnc_roots()
+        nodemanager.setup_nodes(None)  # type: ignore[arg-type]
         for gwspec in nodemanager.specs:
             assert gwspec._samefilesystem()
             assert not gwspec.chdir
@@ -349,7 +385,7 @@ class MyWarning(UserWarning):
         ),
     ],
 )
-def test_unserialize_warning_msg(w_cls):
+def test_unserialize_warning_msg(w_cls: type[Warning] | str) -> None:
     """Test that warning serialization process works well."""
     # Create a test warning message
     with pytest.warns(UserWarning) as w:
@@ -390,7 +426,7 @@ class MyWarningUnknown(UserWarning):
     __module__ = "unknown"
 
 
-def test_warning_serialization_tweaked_module():
+def test_warning_serialization_tweaked_module() -> None:
     """Test for GH#404."""
     # Create a test warning message
     with pytest.warns(UserWarning) as w:
diff --git a/testing/util.py b/testing/util.py
index c7bcc552..649bcce0 100644
--- a/testing/util.py
+++ b/testing/util.py
@@ -5,5 +5,5 @@ class MyWarning2(UserWarning):
     pass
 
 
-def generate_warning():
+def generate_warning() -> None:
     warnings.warn(MyWarning2("hello"))