diff --git a/src/extension.c b/src/extension.c
index bd0986d8c3f..f57cfe3943c 100644
--- a/src/extension.c
+++ b/src/extension.c
@@ -353,3 +353,20 @@ ts_extension_is_proxy_table_relid(Oid relid)
 {
 	return relid == extension_proxy_oid;
 }
+
+#if TS_DEBUG
+static const char *extstate_str[] = {
+	[EXTENSION_STATE_UNKNOWN] = "unknown",
+	[EXTENSION_STATE_TRANSITIONING] = "transitioning",
+	[EXTENSION_STATE_CREATED] = "created",
+	[EXTENSION_STATE_NOT_INSTALLED] = "not installed",
+};
+
+TS_FUNCTION_INFO_V1(ts_extension_get_state);
+
+Datum
+ts_extension_get_state(PG_FUNCTION_ARGS)
+{
+	PG_RETURN_TEXT_P(cstring_to_text(extstate_str[extstate]));
+}
+#endif
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index e4bd594eab0..882db243c8b 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -75,6 +75,24 @@ elseif(REQUIRE_ALL_TESTS)
       "All tests were required but 'pg_isolation_regress' could not be found")
 endif()
 
+if(TAP_CHECKS)
+  add_custom_target(
+    provecheck
+    COMMAND rm -rf ${CMAKE_CURRENT_BINARY_DIR}/tmp_check
+    COMMAND
+      CONFDIR=${CMAKE_BINARY_DIR}/test PATH="${PG_BINDIR}:$ENV{PATH}"
+      PG_REGRESS=${PG_REGRESS} SRC_DIR=${PG_SOURCE_DIR}
+      CM_SRC_DIR=${CMAKE_SOURCE_DIR} PG_LIBDIR=${PG_LIBDIR}
+      ${PRIMARY_TEST_DIR}/pg_prove.sh
+    USES_TERMINAL)
+  list(APPEND _install_checks provecheck)
+elseif(REQUIRE_ALL_TESTS)
+  message(
+    FATAL_ERROR
+      "All tests were required but TAP_CHECKS was off (see previous messages why)"
+  )
+endif()
+
 # We add the installcheck target even when _install_checks is empty as tsl code
 # might add dependencies to it even when regress checks are disabled.
 add_custom_target(installcheck DEPENDS ${_install_checks})
@@ -94,6 +112,7 @@ add_custom_target(installchecklocal DEPENDS ${_local_install_checks})
 
 add_subdirectory(sql)
 add_subdirectory(isolation)
+add_subdirectory(t)
 
 if(PG_SOURCE_DIR)
   add_subdirectory(pgtest)
diff --git a/test/t/001_extension.pl b/test/t/001_extension.pl
new file mode 100644
index 00000000000..7472f3ccb30
--- /dev/null
+++ b/test/t/001_extension.pl
@@ -0,0 +1,97 @@
+# This file and its contents are licensed under the Timescale License.
+# Please see the included NOTICE for copyright information and
+# LICENSE-TIMESCALE for a copy of the license.
+
+use strict;
+use warnings;
+use TimescaleNode;
+use TestLib;
+use Data::Dumper;
+use Test::More tests => 6;
+
+# This test checks that the extension state is handled correctly
+# across multiple sessions. Specifically, if the extension state
+# changes in one session (e.g., the extension is created or dropped),
+# this should be reflected in other concurrent sessions.
+#
+# To test this, we start one interactive "background" psql session
+# that stays open for the duration of the tests and then change the
+# extension state from other sessions.
+my $node = TimescaleNode->create('extension');
+my $in  = '';
+my $out = '';
+my $timer = IPC::Run::timeout(180);
+my $h = $node->interactive_psql('postgres', \$in, \$out, $timer, on_error_stop => 0);
+
+sub check_extension_state
+{
+	my ($pattern, $annotation) = @_;
+
+	# report test failures from caller location
+	local $Test::Builder::Level = $Test::Builder::Level + 1;
+
+	# reset output collector
+	$out = "";
+	# restart per-command timer
+	$timer->start(5);
+	# send the data to be sent
+	$in .= "SELECT * FROM extension_state();\n";
+	# wait ...
+
+	pump $h until ($out =~ $pattern || $timer->is_expired);
+	my $okay = ($out =~ $pattern && !$timer->is_expired);
+	ok($okay, $annotation);
+	# for debugging, log actual output if it didn't match
+	local $Data::Dumper::Terse = 1;
+	local $Data::Dumper::Useqq = 1;
+	diag 'Actual output was ' . Dumper($out) . "Did not match \"$pattern\"\n"
+		if !$okay;
+
+	# Read the next command prompt to prepare for next command
+	$out = "";
+	pump $h until ($out =~ qr/postgres=# / || $timer->is_expired);
+	return;
+}
+
+# Create extension_state function and check initial state
+my $result = $node->safe_psql('postgres',
+q{
+	\ir t/functions.sql
+	SELECT * FROM extension_state();
+});
+
+# Initially, the state should be "created" in both sessions
+is($result, qq/created/, "initial state is \"created\"");
+check_extension_state(qr/created/, "initial state is \"created\"");
+
+# Drop the extension in one session, and the new state should be
+# reflected in the other backend.
+$result = $node->safe_psql('postgres', q{
+	DROP EXTENSION timescaledb;
+	SELECT * FROM extension_state();
+});
+
+# After dropping the extension, the new state in both sessions should
+# be "unknown"
+is($result, qq/unknown/, "state after dropped is \"unknown\"");
+check_extension_state(qr/unknown/, "state is \"unknown\" after extension is dropped in other backend");
+
+# Create the extension again, which should be reflected in both
+# sessions.
+$result = $node->safe_psql('postgres', q{
+	CREATE EXTENSION timescaledb;
+	SELECT * FROM extension_state();
+});
+
+# After creating the extension again in one session, the other session
+# should go back to "created" state.
+is($result, qq/created/, "state after creating extension is \"created\"");
+check_extension_state(qr/created/, "state is \"created\" after extension is created in other backend");
+
+# Quit the interactive psql session
+$in .= q{
+	\q
+};
+
+$h->finish or die "psql returned $?";
+$node->stop;
diff --git a/test/t/CMakeLists.txt b/test/t/CMakeLists.txt
new file mode 100644
index 00000000000..6ce88cec66f
--- /dev/null
+++ b/test/t/CMakeLists.txt
@@ -0,0 +1,12 @@
+set(PROVE_TEST_FILES 001_extension.pl)
+
+if(CMAKE_BUILD_TYPE MATCHES Debug)
+  list(APPEND PROVE_TEST_FILES ${PROVE_DEBUG_TEST_FILES})
+endif(CMAKE_BUILD_TYPE MATCHES Debug)
+
+foreach(P_FILE ${PROVE_TEST_FILES})
+  configure_file(${P_FILE} ${CMAKE_CURRENT_BINARY_DIR}/${P_FILE} COPYONLY)
+endforeach(P_FILE)
+
+set(MODULE_PATHNAME "$libdir/timescaledb-${PROJECT_VERSION_MOD}")
+configure_file(functions.sql.in functions.sql)
diff --git a/test/t/functions.sql.in b/test/t/functions.sql.in
new file mode 100644
index 00000000000..1c087d36a65
--- /dev/null
+++ b/test/t/functions.sql.in
@@ -0,0 +1,2 @@
+CREATE FUNCTION extension_state() RETURNS TEXT
+AS '@MODULE_PATHNAME@', 'ts_extension_get_state' LANGUAGE C;
diff --git a/tsl/test/CMakeLists.txt b/tsl/test/CMakeLists.txt
index e8dc3884cf8..b9d763e71f1 100644
--- a/tsl/test/CMakeLists.txt
+++ b/tsl/test/CMakeLists.txt
@@ -76,7 +76,7 @@ endif()
 
 if(TAP_CHECKS)
   add_custom_target(
-    provecheck
+    provecheck-t
     COMMAND rm -rf ${CMAKE_CURRENT_BINARY_DIR}/tmp_check
     COMMAND
       CONFDIR=${CMAKE_BINARY_DIR}/tsl/test PATH="${PG_BINDIR}:$ENV{PATH}"
@@ -84,7 +84,7 @@ if(TAP_CHECKS)
       CM_SRC_DIR=${CMAKE_SOURCE_DIR} PG_LIBDIR=${PG_LIBDIR}
       ${PRIMARY_TEST_DIR}/pg_prove.sh
     USES_TERMINAL)
-  list(APPEND _install_checks provecheck)
+  list(APPEND _install_checks provecheck-t)
 elseif(REQUIRE_ALL_TESTS)
   message(
     FATAL_ERROR