From 79712b55d27a725e0923fa1a81698f92c87e0f13 Mon Sep 17 00:00:00 2001
From: rajnish-verma-22172 <rajnish.verma@zohocorp.com>
Date: Wed, 21 Oct 2026 11:39:30 +0530
Subject: [PATCH] Copy historic hook call arguments

Snapshot the keyword argument mapping when recording a historic call so mutations by the caller do not alter replay for late plugins. Add regression coverage and document the behavior.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 changelog/808.bugfix.rst    |  1 +
 docs/index.rst              |  4 ++++
 src/pluggy/_caller.py       |  2 +-
 testing/test_invocations.py | 23 +++++++++++++++++++++++
 4 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 changelog/808.bugfix.rst

diff --git a/changelog/808.bugfix.rst b/changelog/808.bugfix.rst
new file mode 100644
index 00000000..9a80ec2a
--- /dev/null
+++ b/changelog/808.bugfix.rst
@@ -0,0 +1 @@
+Historic hook calls now copy their keyword argument mapping, so later changes to the caller's mapping do not affect calls replayed to newly registered plugins.
diff --git a/docs/index.rst b/docs/index.rst
index f2aaf957..9eed1bc8 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -995,6 +995,10 @@ using the :py:meth:`~pluggy.HookCaller.call_historic()` method:
     # historic callback is invoked here
     pm.register(mylateplugin)
 
+The keyword argument mapping is copied when the call is recorded, so later
+changes to the caller's mapping do not affect calls replayed to newly registered
+plugins.
+
 Note that if you :py:meth:`~pluggy.HookCaller.call_historic()`
 the :py:class:`~pluggy.HookCaller` (and thus your calling code)
 can not receive results back from the underlying *hookimpl* functions.
diff --git a/src/pluggy/_caller.py b/src/pluggy/_caller.py
index 52b02316..0b0013c7 100644
--- a/src/pluggy/_caller.py
+++ b/src/pluggy/_caller.py
@@ -215,7 +215,7 @@ def call_historic(
         kwargs = kwargs or {}
         kwargs = self._apply_defaults(kwargs)
         self._verify_all_args_are_provided(kwargs)
-        self._call_history.append((kwargs, result_callback))
+        self._call_history.append((dict(kwargs), result_callback))
         # Historizing hooks don't return results.
         # Remember firstresult isn't compatible with historic.
         # Copy because plugins may register other plugins during iteration (#438).
diff --git a/testing/test_invocations.py b/testing/test_invocations.py
index ccae8aea..18e509df 100644
--- a/testing/test_invocations.py
+++ b/testing/test_invocations.py
@@ -597,6 +597,29 @@ def hello(self, arg, new_arg):
 
         assert seen == [(1, "spec"), (2, "call")]
 
+    def test_historic_replay_copies_call_kwargs(self, pm: PluginManager) -> None:
+        class Api:
+            @hookspec(historic=True)
+            def hello(self, arg):
+                pass
+
+        pm.add_hookspecs(Api)
+
+        kwargs = {"arg": "at-call-time"}
+        pm.hook.hello.call_historic(kwargs=kwargs)
+        kwargs["arg"] = "mutated"
+
+        seen = []
+
+        class Plugin:
+            @hookimpl
+            def hello(self, arg):
+                seen.append(arg)
+
+        pm.register(Plugin())
+
+        assert seen == ["at-call-time"]
+
     def test_call_extra(self, pm: PluginManager) -> None:
         """Test calls with extras respect defaults."""