patchFetch missing submodule objects from default remote

builtin/submodule--helper.c, submodule.c, t/meson.build, t/t5526-fetch-submodules.sh, t/t5572-pull-submodule.sh, t/t7425-submodule-get-default-remote.sh

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index d537ab087a..b180a24091 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -112,6 +112,43 @@ static int get_default_remote_submodule(const char *module_path, char **default_
 	return 0;
 }
 
+static int module_get_default_remote(int argc, const char **argv, const char *prefix,
+				     struct repository *repo UNUSED)
+{
+	const char *path;
+	char *resolved_path = NULL;
+	char *default_remote = NULL;
+	int code;
+	struct option options[] = {
+		OPT_END()
+	};
+	const char *const usage[] = {
+		N_("git submodule--helper get-default-remote <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	path = argv[0];
+	if (prefix && *prefix && !is_absolute_path(path)) {
+		resolved_path = xstrfmt("%s%s", prefix, path);
+		path = resolved_path;
+	}
+
+	code = get_default_remote_submodule(path, &default_remote);
+	if (code) {
+		free(resolved_path);
+		return code;
+	}
+
+	printf("%s\n", default_remote);
+	free(default_remote);
+	free(resolved_path);
+	return 0;
+}
+
 /* the result should be freed by the caller. */
 static char *get_submodule_displaypath(const char *path, const char *prefix,
 				       const char *super_prefix)
@@ -3608,6 +3645,7 @@ int cmd_submodule__helper(int argc,
 		OPT_SUBCOMMAND("set-url", &fn, module_set_url),
 		OPT_SUBCOMMAND("set-branch", &fn, module_set_branch),
 		OPT_SUBCOMMAND("create-branch", &fn, module_create_branch),
+		OPT_SUBCOMMAND("get-default-remote", &fn, module_get_default_remote),
 		OPT_END()
 	};
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
diff --git a/submodule.c b/submodule.c
index 40a5c6fb9d..044fcad6c9 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1706,6 +1706,8 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 	if (spf->oid_fetch_tasks_nr) {
 		struct fetch_task *task =
 			spf->oid_fetch_tasks[spf->oid_fetch_tasks_nr - 1];
+		struct child_process cp_remote = CHILD_PROCESS_INIT;
+		struct strbuf remote_name = STRBUF_INIT;
 		spf->oid_fetch_tasks_nr--;
 
 		child_process_init(cp);
@@ -1719,8 +1721,19 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 		strvec_pushf(&cp->args, "--submodule-prefix=%s%s/",
 			     spf->prefix, task->sub->path);
 
-		/* NEEDSWORK: have get_default_remote from submodule--helper */
-		strvec_push(&cp->args, "origin");
+		cp_remote.git_cmd = 1;
+		strvec_pushl(&cp_remote.args, "submodule--helper",
+			     "get-default-remote", task->sub->path, NULL);
+
+		if (!capture_command(&cp_remote, &remote_name, 0)) {
+			strbuf_trim_trailing_newline(&remote_name);
+			strvec_push(&cp->args, remote_name.buf);
+		} else {
+			// Fallback to "origin" if the helper fails
+			strvec_push(&cp->args, "origin");
+		}
+		strbuf_release(&remote_name);
+
 		oid_array_for_each_unique(task->commits,
 					  append_oid_to_argv, &cp->args);
 
diff --git a/t/meson.build b/t/meson.build
index 459c52a489..ef6cdab165 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -887,6 +887,7 @@ integration_tests = [
   't7422-submodule-output.sh',
   't7423-submodule-symlinks.sh',
   't7424-submodule-mixed-ref-formats.sh',
+  't7425-submodule-get-default-remote.sh',
   't7450-bad-git-dotfiles.sh',
   't7500-commit-template-squash-signoff.sh',
   't7501-commit-basic-functionality.sh',
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 5e566205ba..a5a273b392 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -929,6 +929,58 @@ test_expect_success 'fetch new submodule commit intermittently referenced by sup
 	)
 '
 
+test_expect_success 'fetch --recurse-submodules works with custom remote names' '
+	# depends on the previous test for setup
+
+	# Rename the remote in sub1 from "origin" to "custom_remote"
+	git -C downstream/sub1 remote rename origin custom_remote &&
+
+	# Create new commits in the original submodules
+	C=$(git -C submodule commit-tree -m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom1 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom2 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads for custom remote" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom3 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom3:refs/heads/my_other_branch &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
+test_expect_success 'fetch new submodule commit on-demand in FETCH_HEAD from custom remote' '
+	# depends on the previous test for setup
+
+	C=$(git -C submodule commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom4 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom5 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom6 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom6 &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
 add_commit_push () {
 	dir="$1" &&
 	msg="$2" &&
diff --git a/t/t5572-pull-submodule.sh b/t/t5572-pull-submodule.sh
index 45f384dd32..868dd6d130 100755
--- a/t/t5572-pull-submodule.sh
+++ b/t/t5572-pull-submodule.sh
@@ -257,7 +257,26 @@ test_expect_success 'fetch submodule remote of different name from superproject'
 	git -C a-submodule reset --hard HEAD^^ &&
 
 	git -C child pull --no-recurse-submodules &&
-	git -C child submodule update
+	git -C child submodule update &&
+	test_path_is_file child/a-submodule/moreecho.t
+'
+
+test_expect_success 'fetch submodule remote of different non-origin name from superproject' '
+	git -C child/a-submodule remote rename origin o2 &&
+
+	# Create commit that's unreachable from current master branch
+	git -C a-submodule checkout -b newmain2 master^ &&
+	test_commit -C a-submodule echo_o2 &&
+	test_commit -C a-submodule moreecho_o2 &&
+	subc=$(git -C a-submodule rev-parse --short HEAD) &&
+
+	git -C parent/a-submodule fetch &&
+	git -C parent/a-submodule checkout "$subc" &&
+	git -C parent commit -m "update submodule o2" a-submodule &&
+	git -C a-submodule reset --hard HEAD^^ &&
+
+	git -C child pull --recurse-submodules &&
+	test_path_is_file child/a-submodule/moreecho_o2.t
 '
 
 test_done
diff --git a/t/t7425-submodule-get-default-remote.sh b/t/t7425-submodule-get-default-remote.sh
new file mode 100755
index 0000000000..b842af9a2d
--- /dev/null
+++ b/t/t7425-submodule-get-default-remote.sh
@@ -0,0 +1,186 @@
+#!/bin/sh
+
+test_description='git submodule--helper get-default-remote'
+
+TEST_NO_CREATE_REPO=1
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git config --global protocol.file.allow always
+'
+
+test_expect_success 'setup repositories' '
+	# Create a repository to be used as submodule
+	git init sub &&
+	test_commit --no-tag -C sub "initial commit in sub" file.txt "sub content" &&
+
+	# Create main repository
+	git init super &&
+	(
+		cd super &&
+		mkdir subdir &&
+		test_commit --no-tag -C subdir "initial commit in super" main.txt "super content" &&
+		git submodule add ../sub subpath &&
+		git commit -m "add submodule 'sub' at subpath"
+	)
+'
+
+test_expect_success 'get-default-remote returns origin for initialized submodule' '
+	(
+		cd super &&
+		git submodule update --init &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works from subdirectory' '
+	(
+		cd super/subdir &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote ../subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-existent path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote nonexistent 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-submodule path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subdir 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails without path argument' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with too many arguments' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subpath subdir 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'setup submodule with non-origin default remote name' '
+	# Create another submodule path with a different remote name
+	(
+		cd super &&
+		git submodule add ../sub upstream-subpath &&
+		git commit -m "add second submodule in upstream-subpath" &&
+		git submodule update --init upstream-subpath &&
+
+		# Change the remote name in the submodule
+		cd upstream-subpath &&
+		git remote rename origin upstream
+	)
+'
+
+test_expect_success 'get-default-remote returns non-origin remote name' '
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes' '
+	(
+		cd super/subpath &&
+		git remote add other-upstream ../../sub &&
+		git remote add myfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes and none are origin' '
+	(
+		cd super/upstream-subpath &&
+		git remote add yet-another-upstream ../../sub &&
+		git remote add yourfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'setup nested submodule with non-origin remote' '
+	git init innersub &&
+	test_commit --no-tag -C innersub "initial commit in innersub" inner.txt "innersub content" &&
+
+	(
+		cd sub &&
+		git submodule add ../innersub innersubpath &&
+		git commit -m "add nested submodule at innersubpath"
+	) &&
+
+	(
+		cd super/upstream-subpath &&
+		git pull upstream &&
+		git submodule update --init --recursive . &&
+		(
+			cd innersubpath &&
+			git remote rename origin another_upstream
+		)
+	)
+'
+
+test_expect_success 'get-default-remote works with nested submodule' '
+	(
+		cd super &&
+		echo "another_upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath/innersubpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works with submodule that has no remotes' '
+	# Create a submodule directory manually without remotes
+	(
+		cd super &&
+		git init no-remote-sub &&
+		test_commit --no-tag -C no-remote-sub "local commit" local.txt "local content"
+	) &&
+
+	# Add it as a submodule
+	(
+		cd super &&
+		git submodule add ./no-remote-sub &&
+		git commit -m "add local submodule 'no-remote-sub'"
+	) &&
+
+	(
+		cd super &&
+		# Should fall back to "origin" remote name when no remotes exist
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote no-remote-sub >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_done

builtin/submodule--helper.c, submodule.c, t/meson.build, t/t5526-fetch-submodules.sh, t/t5572-pull-submodule.sh, t/t7425-submodule-get-default-remote.sh

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index d537ab087a..b180a24091 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -112,6 +112,43 @@ static int get_default_remote_submodule(const char *module_path, char **default_
 	return 0;
 }
 
+static int module_get_default_remote(int argc, const char **argv, const char *prefix,
+				     struct repository *repo UNUSED)
+{
+	const char *path;
+	char *resolved_path = NULL;
+	char *default_remote = NULL;
+	int code;
+	struct option options[] = {
+		OPT_END()
+	};
+	const char *const usage[] = {
+		N_("git submodule--helper get-default-remote <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	path = argv[0];
+	if (prefix && *prefix && !is_absolute_path(path)) {
+		resolved_path = xstrfmt("%s%s", prefix, path);
+		path = resolved_path;
+	}
+
+	code = get_default_remote_submodule(path, &default_remote);
+	if (code) {
+		free(resolved_path);
+		return code;
+	}
+
+	printf("%s\n", default_remote);
+	free(default_remote);
+	free(resolved_path);
+	return 0;
+}
+
 /* the result should be freed by the caller. */
 static char *get_submodule_displaypath(const char *path, const char *prefix,
 				       const char *super_prefix)
@@ -3608,6 +3645,7 @@ int cmd_submodule__helper(int argc,
 		OPT_SUBCOMMAND("set-url", &fn, module_set_url),
 		OPT_SUBCOMMAND("set-branch", &fn, module_set_branch),
 		OPT_SUBCOMMAND("create-branch", &fn, module_create_branch),
+		OPT_SUBCOMMAND("get-default-remote", &fn, module_get_default_remote),
 		OPT_END()
 	};
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
diff --git a/submodule.c b/submodule.c
index 40a5c6fb9d..6599657f34 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1706,6 +1706,8 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 	if (spf->oid_fetch_tasks_nr) {
 		struct fetch_task *task =
 			spf->oid_fetch_tasks[spf->oid_fetch_tasks_nr - 1];
+		struct child_process cp_remote = CHILD_PROCESS_INIT;
+		struct strbuf remote_name = STRBUF_INIT;
 		spf->oid_fetch_tasks_nr--;
 
 		child_process_init(cp);
@@ -1719,8 +1721,19 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 		strvec_pushf(&cp->args, "--submodule-prefix=%s%s/",
 			     spf->prefix, task->sub->path);
 
-		/* NEEDSWORK: have get_default_remote from submodule--helper */
-		strvec_push(&cp->args, "origin");
+		cp_remote.git_cmd = 1;
+		strvec_pushl(&cp_remote.args, "submodule--helper",
+			     "get-default-remote", task->sub->path, NULL);
+
+		if (!capture_command(&cp_remote, &remote_name, 0)) {
+			strbuf_trim_trailing_newline(&remote_name);
+			strvec_push(&cp->args, remote_name.buf);
+		} else {
+			/* Fallback to "origin" if the helper fails */
+			strvec_push(&cp->args, "origin");
+		}
+		strbuf_release(&remote_name);
+
 		oid_array_for_each_unique(task->commits,
 					  append_oid_to_argv, &cp->args);
 
diff --git a/t/meson.build b/t/meson.build
index 459c52a489..ef6cdab165 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -887,6 +887,7 @@ integration_tests = [
   't7422-submodule-output.sh',
   't7423-submodule-symlinks.sh',
   't7424-submodule-mixed-ref-formats.sh',
+  't7425-submodule-get-default-remote.sh',
   't7450-bad-git-dotfiles.sh',
   't7500-commit-template-squash-signoff.sh',
   't7501-commit-basic-functionality.sh',
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 5e566205ba..a5a273b392 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -929,6 +929,58 @@ test_expect_success 'fetch new submodule commit intermittently referenced by sup
 	)
 '
 
+test_expect_success 'fetch --recurse-submodules works with custom remote names' '
+	# depends on the previous test for setup
+
+	# Rename the remote in sub1 from "origin" to "custom_remote"
+	git -C downstream/sub1 remote rename origin custom_remote &&
+
+	# Create new commits in the original submodules
+	C=$(git -C submodule commit-tree -m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom1 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom2 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads for custom remote" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom3 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom3:refs/heads/my_other_branch &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
+test_expect_success 'fetch new submodule commit on-demand in FETCH_HEAD from custom remote' '
+	# depends on the previous test for setup
+
+	C=$(git -C submodule commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom4 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom5 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom6 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom6 &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
 add_commit_push () {
 	dir="$1" &&
 	msg="$2" &&
diff --git a/t/t5572-pull-submodule.sh b/t/t5572-pull-submodule.sh
index 45f384dd32..868dd6d130 100755
--- a/t/t5572-pull-submodule.sh
+++ b/t/t5572-pull-submodule.sh
@@ -257,7 +257,26 @@ test_expect_success 'fetch submodule remote of different name from superproject'
 	git -C a-submodule reset --hard HEAD^^ &&
 
 	git -C child pull --no-recurse-submodules &&
-	git -C child submodule update
+	git -C child submodule update &&
+	test_path_is_file child/a-submodule/moreecho.t
+'
+
+test_expect_success 'fetch submodule remote of different non-origin name from superproject' '
+	git -C child/a-submodule remote rename origin o2 &&
+
+	# Create commit that's unreachable from current master branch
+	git -C a-submodule checkout -b newmain2 master^ &&
+	test_commit -C a-submodule echo_o2 &&
+	test_commit -C a-submodule moreecho_o2 &&
+	subc=$(git -C a-submodule rev-parse --short HEAD) &&
+
+	git -C parent/a-submodule fetch &&
+	git -C parent/a-submodule checkout "$subc" &&
+	git -C parent commit -m "update submodule o2" a-submodule &&
+	git -C a-submodule reset --hard HEAD^^ &&
+
+	git -C child pull --recurse-submodules &&
+	test_path_is_file child/a-submodule/moreecho_o2.t
 '
 
 test_done
diff --git a/t/t7425-submodule-get-default-remote.sh b/t/t7425-submodule-get-default-remote.sh
new file mode 100755
index 0000000000..b842af9a2d
--- /dev/null
+++ b/t/t7425-submodule-get-default-remote.sh
@@ -0,0 +1,186 @@
+#!/bin/sh
+
+test_description='git submodule--helper get-default-remote'
+
+TEST_NO_CREATE_REPO=1
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git config --global protocol.file.allow always
+'
+
+test_expect_success 'setup repositories' '
+	# Create a repository to be used as submodule
+	git init sub &&
+	test_commit --no-tag -C sub "initial commit in sub" file.txt "sub content" &&
+
+	# Create main repository
+	git init super &&
+	(
+		cd super &&
+		mkdir subdir &&
+		test_commit --no-tag -C subdir "initial commit in super" main.txt "super content" &&
+		git submodule add ../sub subpath &&
+		git commit -m "add submodule 'sub' at subpath"
+	)
+'
+
+test_expect_success 'get-default-remote returns origin for initialized submodule' '
+	(
+		cd super &&
+		git submodule update --init &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works from subdirectory' '
+	(
+		cd super/subdir &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote ../subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-existent path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote nonexistent 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-submodule path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subdir 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails without path argument' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with too many arguments' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subpath subdir 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'setup submodule with non-origin default remote name' '
+	# Create another submodule path with a different remote name
+	(
+		cd super &&
+		git submodule add ../sub upstream-subpath &&
+		git commit -m "add second submodule in upstream-subpath" &&
+		git submodule update --init upstream-subpath &&
+
+		# Change the remote name in the submodule
+		cd upstream-subpath &&
+		git remote rename origin upstream
+	)
+'
+
+test_expect_success 'get-default-remote returns non-origin remote name' '
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes' '
+	(
+		cd super/subpath &&
+		git remote add other-upstream ../../sub &&
+		git remote add myfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes and none are origin' '
+	(
+		cd super/upstream-subpath &&
+		git remote add yet-another-upstream ../../sub &&
+		git remote add yourfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'setup nested submodule with non-origin remote' '
+	git init innersub &&
+	test_commit --no-tag -C innersub "initial commit in innersub" inner.txt "innersub content" &&
+
+	(
+		cd sub &&
+		git submodule add ../innersub innersubpath &&
+		git commit -m "add nested submodule at innersubpath"
+	) &&
+
+	(
+		cd super/upstream-subpath &&
+		git pull upstream &&
+		git submodule update --init --recursive . &&
+		(
+			cd innersubpath &&
+			git remote rename origin another_upstream
+		)
+	)
+'
+
+test_expect_success 'get-default-remote works with nested submodule' '
+	(
+		cd super &&
+		echo "another_upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath/innersubpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works with submodule that has no remotes' '
+	# Create a submodule directory manually without remotes
+	(
+		cd super &&
+		git init no-remote-sub &&
+		test_commit --no-tag -C no-remote-sub "local commit" local.txt "local content"
+	) &&
+
+	# Add it as a submodule
+	(
+		cd super &&
+		git submodule add ./no-remote-sub &&
+		git commit -m "add local submodule 'no-remote-sub'"
+	) &&
+
+	(
+		cd super &&
+		# Should fall back to "origin" remote name when no remotes exist
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote no-remote-sub >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_done

builtin/submodule--helper.c, submodule.c, t/meson.build, t/t5526-fetch-submodules.sh, t/t5572-pull-submodule.sh, t/t7425-submodule-get-default-remote.sh

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index d537ab087a..b180a24091 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -112,6 +112,43 @@ static int get_default_remote_submodule(const char *module_path, char **default_
 	return 0;
 }
 
+static int module_get_default_remote(int argc, const char **argv, const char *prefix,
+				     struct repository *repo UNUSED)
+{
+	const char *path;
+	char *resolved_path = NULL;
+	char *default_remote = NULL;
+	int code;
+	struct option options[] = {
+		OPT_END()
+	};
+	const char *const usage[] = {
+		N_("git submodule--helper get-default-remote <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	path = argv[0];
+	if (prefix && *prefix && !is_absolute_path(path)) {
+		resolved_path = xstrfmt("%s%s", prefix, path);
+		path = resolved_path;
+	}
+
+	code = get_default_remote_submodule(path, &default_remote);
+	if (code) {
+		free(resolved_path);
+		return code;
+	}
+
+	printf("%s\n", default_remote);
+	free(default_remote);
+	free(resolved_path);
+	return 0;
+}
+
 /* the result should be freed by the caller. */
 static char *get_submodule_displaypath(const char *path, const char *prefix,
 				       const char *super_prefix)
@@ -3608,6 +3645,7 @@ int cmd_submodule__helper(int argc,
 		OPT_SUBCOMMAND("set-url", &fn, module_set_url),
 		OPT_SUBCOMMAND("set-branch", &fn, module_set_branch),
 		OPT_SUBCOMMAND("create-branch", &fn, module_create_branch),
+		OPT_SUBCOMMAND("get-default-remote", &fn, module_get_default_remote),
 		OPT_END()
 	};
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
diff --git a/submodule.c b/submodule.c
index 40a5c6fb9d..6599657f34 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1706,6 +1706,8 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 	if (spf->oid_fetch_tasks_nr) {
 		struct fetch_task *task =
 			spf->oid_fetch_tasks[spf->oid_fetch_tasks_nr - 1];
+		struct child_process cp_remote = CHILD_PROCESS_INIT;
+		struct strbuf remote_name = STRBUF_INIT;
 		spf->oid_fetch_tasks_nr--;
 
 		child_process_init(cp);
@@ -1719,8 +1721,19 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 		strvec_pushf(&cp->args, "--submodule-prefix=%s%s/",
 			     spf->prefix, task->sub->path);
 
-		/* NEEDSWORK: have get_default_remote from submodule--helper */
-		strvec_push(&cp->args, "origin");
+		cp_remote.git_cmd = 1;
+		strvec_pushl(&cp_remote.args, "submodule--helper",
+			     "get-default-remote", task->sub->path, NULL);
+
+		if (!capture_command(&cp_remote, &remote_name, 0)) {
+			strbuf_trim_trailing_newline(&remote_name);
+			strvec_push(&cp->args, remote_name.buf);
+		} else {
+			/* Fallback to "origin" if the helper fails */
+			strvec_push(&cp->args, "origin");
+		}
+		strbuf_release(&remote_name);
+
 		oid_array_for_each_unique(task->commits,
 					  append_oid_to_argv, &cp->args);
 
diff --git a/t/meson.build b/t/meson.build
index 459c52a489..ef6cdab165 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -887,6 +887,7 @@ integration_tests = [
   't7422-submodule-output.sh',
   't7423-submodule-symlinks.sh',
   't7424-submodule-mixed-ref-formats.sh',
+  't7425-submodule-get-default-remote.sh',
   't7450-bad-git-dotfiles.sh',
   't7500-commit-template-squash-signoff.sh',
   't7501-commit-basic-functionality.sh',
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 5e566205ba..a5a273b392 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -929,6 +929,58 @@ test_expect_success 'fetch new submodule commit intermittently referenced by sup
 	)
 '
 
+test_expect_success 'fetch --recurse-submodules works with custom remote names' '
+	# depends on the previous test for setup
+
+	# Rename the remote in sub1 from "origin" to "custom_remote"
+	git -C downstream/sub1 remote rename origin custom_remote &&
+
+	# Create new commits in the original submodules
+	C=$(git -C submodule commit-tree -m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom1 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom2 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads for custom remote" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom3 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom3:refs/heads/my_other_branch &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
+test_expect_success 'fetch new submodule commit on-demand in FETCH_HEAD from custom remote' '
+	# depends on the previous test for setup
+
+	C=$(git -C submodule commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom4 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom5 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom6 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom6 &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
 add_commit_push () {
 	dir="$1" &&
 	msg="$2" &&
diff --git a/t/t5572-pull-submodule.sh b/t/t5572-pull-submodule.sh
index 45f384dd32..faafe31409 100755
--- a/t/t5572-pull-submodule.sh
+++ b/t/t5572-pull-submodule.sh
@@ -257,7 +257,26 @@ test_expect_success 'fetch submodule remote of different name from superproject'
 	git -C a-submodule reset --hard HEAD^^ &&
 
 	git -C child pull --no-recurse-submodules &&
-	git -C child submodule update
+	git -C child submodule update &&
+	test_path_is_file child/a-submodule/moreecho.t
+'
+
+test_expect_success 'fetch submodule remote of different non-origin name from superproject' '
+	git -C child/a-submodule remote rename origin o2 &&
+
+	# Create commit that is unreachable from current master branch
+	git -C a-submodule checkout -b newmain2 master^ &&
+	test_commit -C a-submodule echo_o2 &&
+	test_commit -C a-submodule moreecho_o2 &&
+	subc=$(git -C a-submodule rev-parse --short HEAD) &&
+
+	git -C parent/a-submodule fetch &&
+	git -C parent/a-submodule checkout "$subc" &&
+	git -C parent commit -m "update submodule o2" a-submodule &&
+	git -C a-submodule reset --hard HEAD^^ &&
+
+	git -C child pull --recurse-submodules &&
+	test_path_is_file child/a-submodule/moreecho_o2.t
 '
 
 test_done
diff --git a/t/t7425-submodule-get-default-remote.sh b/t/t7425-submodule-get-default-remote.sh
new file mode 100755
index 0000000000..b842af9a2d
--- /dev/null
+++ b/t/t7425-submodule-get-default-remote.sh
@@ -0,0 +1,186 @@
+#!/bin/sh
+
+test_description='git submodule--helper get-default-remote'
+
+TEST_NO_CREATE_REPO=1
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git config --global protocol.file.allow always
+'
+
+test_expect_success 'setup repositories' '
+	# Create a repository to be used as submodule
+	git init sub &&
+	test_commit --no-tag -C sub "initial commit in sub" file.txt "sub content" &&
+
+	# Create main repository
+	git init super &&
+	(
+		cd super &&
+		mkdir subdir &&
+		test_commit --no-tag -C subdir "initial commit in super" main.txt "super content" &&
+		git submodule add ../sub subpath &&
+		git commit -m "add submodule 'sub' at subpath"
+	)
+'
+
+test_expect_success 'get-default-remote returns origin for initialized submodule' '
+	(
+		cd super &&
+		git submodule update --init &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works from subdirectory' '
+	(
+		cd super/subdir &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote ../subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-existent path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote nonexistent 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-submodule path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subdir 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails without path argument' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with too many arguments' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subpath subdir 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'setup submodule with non-origin default remote name' '
+	# Create another submodule path with a different remote name
+	(
+		cd super &&
+		git submodule add ../sub upstream-subpath &&
+		git commit -m "add second submodule in upstream-subpath" &&
+		git submodule update --init upstream-subpath &&
+
+		# Change the remote name in the submodule
+		cd upstream-subpath &&
+		git remote rename origin upstream
+	)
+'
+
+test_expect_success 'get-default-remote returns non-origin remote name' '
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes' '
+	(
+		cd super/subpath &&
+		git remote add other-upstream ../../sub &&
+		git remote add myfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes and none are origin' '
+	(
+		cd super/upstream-subpath &&
+		git remote add yet-another-upstream ../../sub &&
+		git remote add yourfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'setup nested submodule with non-origin remote' '
+	git init innersub &&
+	test_commit --no-tag -C innersub "initial commit in innersub" inner.txt "innersub content" &&
+
+	(
+		cd sub &&
+		git submodule add ../innersub innersubpath &&
+		git commit -m "add nested submodule at innersubpath"
+	) &&
+
+	(
+		cd super/upstream-subpath &&
+		git pull upstream &&
+		git submodule update --init --recursive . &&
+		(
+			cd innersubpath &&
+			git remote rename origin another_upstream
+		)
+	)
+'
+
+test_expect_success 'get-default-remote works with nested submodule' '
+	(
+		cd super &&
+		echo "another_upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath/innersubpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works with submodule that has no remotes' '
+	# Create a submodule directory manually without remotes
+	(
+		cd super &&
+		git init no-remote-sub &&
+		test_commit --no-tag -C no-remote-sub "local commit" local.txt "local content"
+	) &&
+
+	# Add it as a submodule
+	(
+		cd super &&
+		git submodule add ./no-remote-sub &&
+		git commit -m "add local submodule 'no-remote-sub'"
+	) &&
+
+	(
+		cd super &&
+		# Should fall back to "origin" remote name when no remotes exist
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote no-remote-sub >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_done

builtin/submodule--helper.c, submodule.c, t/meson.build, t/t5526-fetch-submodules.sh, t/t5572-pull-submodule.sh, t/t7426-submodule-get-default-remote.sh

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index d537ab087a..b180a24091 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -112,6 +112,43 @@ static int get_default_remote_submodule(const char *module_path, char **default_
 	return 0;
 }
 
+static int module_get_default_remote(int argc, const char **argv, const char *prefix,
+				     struct repository *repo UNUSED)
+{
+	const char *path;
+	char *resolved_path = NULL;
+	char *default_remote = NULL;
+	int code;
+	struct option options[] = {
+		OPT_END()
+	};
+	const char *const usage[] = {
+		N_("git submodule--helper get-default-remote <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	path = argv[0];
+	if (prefix && *prefix && !is_absolute_path(path)) {
+		resolved_path = xstrfmt("%s%s", prefix, path);
+		path = resolved_path;
+	}
+
+	code = get_default_remote_submodule(path, &default_remote);
+	if (code) {
+		free(resolved_path);
+		return code;
+	}
+
+	printf("%s\n", default_remote);
+	free(default_remote);
+	free(resolved_path);
+	return 0;
+}
+
 /* the result should be freed by the caller. */
 static char *get_submodule_displaypath(const char *path, const char *prefix,
 				       const char *super_prefix)
@@ -3608,6 +3645,7 @@ int cmd_submodule__helper(int argc,
 		OPT_SUBCOMMAND("set-url", &fn, module_set_url),
 		OPT_SUBCOMMAND("set-branch", &fn, module_set_branch),
 		OPT_SUBCOMMAND("create-branch", &fn, module_create_branch),
+		OPT_SUBCOMMAND("get-default-remote", &fn, module_get_default_remote),
 		OPT_END()
 	};
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
diff --git a/submodule.c b/submodule.c
index 40a5c6fb9d..6599657f34 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1706,6 +1706,8 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 	if (spf->oid_fetch_tasks_nr) {
 		struct fetch_task *task =
 			spf->oid_fetch_tasks[spf->oid_fetch_tasks_nr - 1];
+		struct child_process cp_remote = CHILD_PROCESS_INIT;
+		struct strbuf remote_name = STRBUF_INIT;
 		spf->oid_fetch_tasks_nr--;
 
 		child_process_init(cp);
@@ -1719,8 +1721,19 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 		strvec_pushf(&cp->args, "--submodule-prefix=%s%s/",
 			     spf->prefix, task->sub->path);
 
-		/* NEEDSWORK: have get_default_remote from submodule--helper */
-		strvec_push(&cp->args, "origin");
+		cp_remote.git_cmd = 1;
+		strvec_pushl(&cp_remote.args, "submodule--helper",
+			     "get-default-remote", task->sub->path, NULL);
+
+		if (!capture_command(&cp_remote, &remote_name, 0)) {
+			strbuf_trim_trailing_newline(&remote_name);
+			strvec_push(&cp->args, remote_name.buf);
+		} else {
+			/* Fallback to "origin" if the helper fails */
+			strvec_push(&cp->args, "origin");
+		}
+		strbuf_release(&remote_name);
+
 		oid_array_for_each_unique(task->commits,
 					  append_oid_to_argv, &cp->args);
 
diff --git a/t/meson.build b/t/meson.build
index 459c52a489..6ff54cf276 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -887,6 +887,7 @@ integration_tests = [
   't7422-submodule-output.sh',
   't7423-submodule-symlinks.sh',
   't7424-submodule-mixed-ref-formats.sh',
+  't7426-submodule-get-default-remote.sh',
   't7450-bad-git-dotfiles.sh',
   't7500-commit-template-squash-signoff.sh',
   't7501-commit-basic-functionality.sh',
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 5e566205ba..a5a273b392 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -929,6 +929,58 @@ test_expect_success 'fetch new submodule commit intermittently referenced by sup
 	)
 '
 
+test_expect_success 'fetch --recurse-submodules works with custom remote names' '
+	# depends on the previous test for setup
+
+	# Rename the remote in sub1 from "origin" to "custom_remote"
+	git -C downstream/sub1 remote rename origin custom_remote &&
+
+	# Create new commits in the original submodules
+	C=$(git -C submodule commit-tree -m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom1 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom2 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads for custom remote" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom3 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom3:refs/heads/my_other_branch &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
+test_expect_success 'fetch new submodule commit on-demand in FETCH_HEAD from custom remote' '
+	# depends on the previous test for setup
+
+	C=$(git -C submodule commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom4 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom5 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom6 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom6 &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
 add_commit_push () {
 	dir="$1" &&
 	msg="$2" &&
diff --git a/t/t5572-pull-submodule.sh b/t/t5572-pull-submodule.sh
index 45f384dd32..dfc07d050b 100755
--- a/t/t5572-pull-submodule.sh
+++ b/t/t5572-pull-submodule.sh
@@ -246,7 +246,8 @@ test_expect_success 'fetch submodule remote of different name from superproject'
 	git -C child submodule update --init &&
 
 	# Needs to create unreachable commit from current master branch.
-	git -C a-submodule checkout -b newmain HEAD^ &&
+	git -C a-submodule tag anchorpoint HEAD &&
+	git -C a-submodule checkout -b newmain anchorpoint^ &&
 	test_commit -C a-submodule echo &&
 	test_commit -C a-submodule moreecho &&
 	subc=$(git -C a-submodule rev-parse --short HEAD) &&
@@ -257,7 +258,26 @@ test_expect_success 'fetch submodule remote of different name from superproject'
 	git -C a-submodule reset --hard HEAD^^ &&
 
 	git -C child pull --no-recurse-submodules &&
-	git -C child submodule update
+	git -C child submodule update &&
+	test_path_is_file child/a-submodule/moreecho.t
+'
+
+test_expect_success 'fetch submodule remote of different non-origin name from superproject' '
+	git -C child/a-submodule remote rename origin o2 &&
+
+	# Create commit that is unreachable from current master branch
+	git -C a-submodule checkout -b newmain2 anchorpoint^ &&
+	test_commit -C a-submodule echo_o2 &&
+	test_commit -C a-submodule moreecho_o2 &&
+	subc=$(git -C a-submodule rev-parse --short HEAD) &&
+
+	git -C parent/a-submodule fetch &&
+	git -C parent/a-submodule checkout "$subc" &&
+	git -C parent commit -m "update submodule o2" a-submodule &&
+	git -C a-submodule reset --hard HEAD^^ &&
+
+	git -C child pull --recurse-submodules &&
+	test_path_is_file child/a-submodule/moreecho_o2.t
 '
 
 test_done
diff --git a/t/t7426-submodule-get-default-remote.sh b/t/t7426-submodule-get-default-remote.sh
new file mode 100755
index 0000000000..b842af9a2d
--- /dev/null
+++ b/t/t7426-submodule-get-default-remote.sh
@@ -0,0 +1,186 @@
+#!/bin/sh
+
+test_description='git submodule--helper get-default-remote'
+
+TEST_NO_CREATE_REPO=1
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git config --global protocol.file.allow always
+'
+
+test_expect_success 'setup repositories' '
+	# Create a repository to be used as submodule
+	git init sub &&
+	test_commit --no-tag -C sub "initial commit in sub" file.txt "sub content" &&
+
+	# Create main repository
+	git init super &&
+	(
+		cd super &&
+		mkdir subdir &&
+		test_commit --no-tag -C subdir "initial commit in super" main.txt "super content" &&
+		git submodule add ../sub subpath &&
+		git commit -m "add submodule 'sub' at subpath"
+	)
+'
+
+test_expect_success 'get-default-remote returns origin for initialized submodule' '
+	(
+		cd super &&
+		git submodule update --init &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works from subdirectory' '
+	(
+		cd super/subdir &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote ../subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-existent path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote nonexistent 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-submodule path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subdir 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails without path argument' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with too many arguments' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subpath subdir 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'setup submodule with non-origin default remote name' '
+	# Create another submodule path with a different remote name
+	(
+		cd super &&
+		git submodule add ../sub upstream-subpath &&
+		git commit -m "add second submodule in upstream-subpath" &&
+		git submodule update --init upstream-subpath &&
+
+		# Change the remote name in the submodule
+		cd upstream-subpath &&
+		git remote rename origin upstream
+	)
+'
+
+test_expect_success 'get-default-remote returns non-origin remote name' '
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes' '
+	(
+		cd super/subpath &&
+		git remote add other-upstream ../../sub &&
+		git remote add myfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes and none are origin' '
+	(
+		cd super/upstream-subpath &&
+		git remote add yet-another-upstream ../../sub &&
+		git remote add yourfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'setup nested submodule with non-origin remote' '
+	git init innersub &&
+	test_commit --no-tag -C innersub "initial commit in innersub" inner.txt "innersub content" &&
+
+	(
+		cd sub &&
+		git submodule add ../innersub innersubpath &&
+		git commit -m "add nested submodule at innersubpath"
+	) &&
+
+	(
+		cd super/upstream-subpath &&
+		git pull upstream &&
+		git submodule update --init --recursive . &&
+		(
+			cd innersubpath &&
+			git remote rename origin another_upstream
+		)
+	)
+'
+
+test_expect_success 'get-default-remote works with nested submodule' '
+	(
+		cd super &&
+		echo "another_upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath/innersubpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works with submodule that has no remotes' '
+	# Create a submodule directory manually without remotes
+	(
+		cd super &&
+		git init no-remote-sub &&
+		test_commit --no-tag -C no-remote-sub "local commit" local.txt "local content"
+	) &&
+
+	# Add it as a submodule
+	(
+		cd super &&
+		git submodule add ./no-remote-sub &&
+		git commit -m "add local submodule 'no-remote-sub'"
+	) &&
+
+	(
+		cd super &&
+		# Should fall back to "origin" remote name when no remotes exist
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote no-remote-sub >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_done

diff --git a/t/t5572-pull-submodule.sh b/t/t5572-pull-submodule.sh
index faafe31409..dfc07d050b 100755
--- a/t/t5572-pull-submodule.sh
+++ b/t/t5572-pull-submodule.sh
@@ -246,7 +246,8 @@ test_expect_success 'fetch submodule remote of different name from superproject'
 	git -C child submodule update --init &&
 
 	# Needs to create unreachable commit from current master branch.
-	git -C a-submodule checkout -b newmain HEAD^ &&
+	git -C a-submodule tag anchorpoint HEAD &&
+	git -C a-submodule checkout -b newmain anchorpoint^ &&
 	test_commit -C a-submodule echo &&
 	test_commit -C a-submodule moreecho &&
 	subc=$(git -C a-submodule rev-parse --short HEAD) &&
@@ -265,7 +266,7 @@ test_expect_success 'fetch submodule remote of different non-origin name from su
 	git -C child/a-submodule remote rename origin o2 &&
 
 	# Create commit that is unreachable from current master branch
-	git -C a-submodule checkout -b newmain2 master^ &&
+	git -C a-submodule checkout -b newmain2 anchorpoint^ &&
 	test_commit -C a-submodule echo_o2 &&
 	test_commit -C a-submodule moreecho_o2 &&
 	subc=$(git -C a-submodule rev-parse --short HEAD) &&

builtin/submodule--helper.c, submodule.c, t/meson.build, t/t5526-fetch-submodules.sh, t/t5572-pull-submodule.sh, t/t7426-submodule-get-default-remote.sh

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index b621d14275..0a4676f3ba 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -113,6 +113,43 @@ static int get_default_remote_submodule(const char *module_path, char **default_
 	return 0;
 }
 
+static int module_get_default_remote(int argc, const char **argv, const char *prefix,
+				     struct repository *repo UNUSED)
+{
+	const char *path;
+	char *resolved_path = NULL;
+	char *default_remote = NULL;
+	int code;
+	struct option options[] = {
+		OPT_END()
+	};
+	const char *const usage[] = {
+		N_("git submodule--helper get-default-remote <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	path = argv[0];
+	if (prefix && *prefix && !is_absolute_path(path)) {
+		resolved_path = xstrfmt("%s%s", prefix, path);
+		path = resolved_path;
+	}
+
+	code = get_default_remote_submodule(path, &default_remote);
+	if (code) {
+		free(resolved_path);
+		return code;
+	}
+
+	printf("%s\n", default_remote);
+	free(default_remote);
+	free(resolved_path);
+	return 0;
+}
+
 /* the result should be freed by the caller. */
 static char *get_submodule_displaypath(const char *path, const char *prefix,
 				       const char *super_prefix)
@@ -3788,6 +3825,7 @@ int cmd_submodule__helper(int argc,
 		OPT_SUBCOMMAND("set-url", &fn, module_set_url),
 		OPT_SUBCOMMAND("set-branch", &fn, module_set_branch),
 		OPT_SUBCOMMAND("create-branch", &fn, module_create_branch),
+		OPT_SUBCOMMAND("get-default-remote", &fn, module_get_default_remote),
 		OPT_END()
 	};
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
diff --git a/submodule.c b/submodule.c
index 508938e4da..906febfa0e 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1708,6 +1708,8 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 	if (spf->oid_fetch_tasks_nr) {
 		struct fetch_task *task =
 			spf->oid_fetch_tasks[spf->oid_fetch_tasks_nr - 1];
+		struct child_process cp_remote = CHILD_PROCESS_INIT;
+		struct strbuf remote_name = STRBUF_INIT;
 		spf->oid_fetch_tasks_nr--;
 
 		child_process_init(cp);
@@ -1721,8 +1723,19 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 		strvec_pushf(&cp->args, "--submodule-prefix=%s%s/",
 			     spf->prefix, task->sub->path);
 
-		/* NEEDSWORK: have get_default_remote from submodule--helper */
-		strvec_push(&cp->args, "origin");
+		cp_remote.git_cmd = 1;
+		strvec_pushl(&cp_remote.args, "submodule--helper",
+			     "get-default-remote", task->sub->path, NULL);
+
+		if (!capture_command(&cp_remote, &remote_name, 0)) {
+			strbuf_trim_trailing_newline(&remote_name);
+			strvec_push(&cp->args, remote_name.buf);
+		} else {
+			/* Fallback to "origin" if the helper fails */
+			strvec_push(&cp->args, "origin");
+		}
+		strbuf_release(&remote_name);
+
 		oid_array_for_each_unique(task->commits,
 					  append_oid_to_argv, &cp->args);
 
diff --git a/t/meson.build b/t/meson.build
index e5174ee575..bf241a7a1e 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -894,6 +894,7 @@ integration_tests = [
   't7423-submodule-symlinks.sh',
   't7424-submodule-mixed-ref-formats.sh',
   't7425-submodule-gitdir-path-extension.sh',
+  't7426-submodule-get-default-remote.sh',
   't7450-bad-git-dotfiles.sh',
   't7500-commit-template-squash-signoff.sh',
   't7501-commit-basic-functionality.sh',
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 5e566205ba..19c0f05144 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -836,9 +836,34 @@ test_expect_success "fetch new submodule commits on-demand outside standard refs
 	git update-ref refs/changes/3 $E &&
 	(
 		cd downstream &&
-		git fetch --recurse-submodules origin refs/changes/3:refs/heads/my_branch &&
+		DEEP_START=$(git -C submodule/subdir/deepsubmodule rev-parse --short origin/deep) &&
+		DEEP_END=$(git -C "$pwd/deepsubmodule" rev-parse --short deep) &&
+		cat >"expect_fetch" <<-EOF &&
+		From $pwd/.
+		 * [new ref]         refs/changes/3 -> my_branch
+		Fetching submodule sub1
+		Fetching submodule sub1/subdir/deepsubmodule
+		Fetching submodule submodule
+		Fetching submodule submodule/subdir/deepsubmodule
+		From $pwd/deepsubmodule
+		   $DEEP_START..$DEEP_END  deep       -> origin/deep
+		From $pwd/./sub1
+		 * branch            $D -> FETCH_HEAD
+		Fetching submodule sub1/subdir/deepsubmodule
+		From $pwd/submodule
+		 * branch            $C -> FETCH_HEAD
+		Fetching submodule submodule/subdir/deepsubmodule
+		EOF
+		test_when_finished "rm -f $pwd/on-demand_submodule_fetch_trace" &&
+		GIT_TRACE="$pwd/on-demand_submodule_fetch_trace" \
+		git fetch --recurse-submodules origin refs/changes/3:refs/heads/my_branch 2>actual_fetch &&
+		test_cmp expect_fetch actual_fetch &&
 		git -C submodule cat-file -t $C &&
 		git -C sub1 cat-file -t $D &&
+		test_grep "trace: built-in: git submodule--helper get-default-remote sub1" \
+			"$pwd/on-demand_submodule_fetch_trace" &&
+		test_grep "trace: built-in: git fetch .* --submodule-prefix=sub1/ origin" \
+			"$pwd/on-demand_submodule_fetch_trace" &&
 		git checkout --recurse-submodules FETCH_HEAD
 	)
 '
@@ -929,6 +954,90 @@ test_expect_success 'fetch new submodule commit intermittently referenced by sup
 	)
 '
 
+test_expect_success 'fetch new submodule commits on-demand outside standard refspec with custom remote name' '
+	# depends on the previous test for setup
+
+	# Rename the remote in sub1 from "origin" to "custom_remote"
+	git -C downstream/sub1 remote rename origin custom_remote &&
+
+	# Create new commits in the original submodules
+	C=$(git -C submodule commit-tree \
+		-m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom1 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree \
+		-m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom2 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit \
+		-m "updated submodules outside of refs/heads for custom remote" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom3 $E &&
+	(
+		cd downstream &&
+		DEEP_START=$(git -C submodule/subdir/deepsubmodule rev-parse --short \
+			origin/deep) &&
+		DEEP_END=$(git -C "$pwd/deepsubmodule" rev-parse --short deep) &&
+		cat >"expect_fetch_custom" <<-EOF &&
+		From $pwd/.
+		 * [new ref]         refs/changes/custom3 -> my_other_branch
+		Fetching submodule sub1
+		Fetching submodule sub1/subdir/deepsubmodule
+		Fetching submodule submodule
+		Fetching submodule submodule/subdir/deepsubmodule
+		From $pwd/./sub1
+		 * branch            $D -> FETCH_HEAD
+		Fetching submodule sub1/subdir/deepsubmodule
+		From $pwd/submodule
+		 * branch            $C -> FETCH_HEAD
+		Fetching submodule submodule/subdir/deepsubmodule
+		EOF
+		test_when_finished "rm -f $pwd/custom_on-demand_submodule_fetch_trace" &&
+		GIT_TRACE="$pwd/custom_on-demand_submodule_fetch_trace" \
+		git fetch --recurse-submodules origin \
+			refs/changes/custom3:refs/heads/my_other_branch \
+			2>actual_fetch_custom &&
+		# the without .gitmodules test above causes warnings
+		grep -v "^warning: " actual_fetch_custom >actual_fetch_warnings_removed &&
+		test_cmp expect_fetch_custom actual_fetch_warnings_removed &&
+
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		test_grep "trace: built-in: git submodule--helper get-default-remote sub1" \
+			"$pwd/custom_on-demand_submodule_fetch_trace" &&
+		test_grep "trace: built-in: git fetch .* --submodule-prefix=sub1/ custom_remote $D" \
+			"$pwd/custom_on-demand_submodule_fetch_trace" &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
+test_expect_success 'fetch new submodule commit on-demand in FETCH_HEAD from custom remote' '
+	# depends on the previous test for setup
+
+	C=$(git -C submodule commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom4 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom5 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom6 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom6 &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
 add_commit_push () {
 	dir="$1" &&
 	msg="$2" &&
diff --git a/t/t5572-pull-submodule.sh b/t/t5572-pull-submodule.sh
index 45f384dd32..42d14328b6 100755
--- a/t/t5572-pull-submodule.sh
+++ b/t/t5572-pull-submodule.sh
@@ -257,7 +257,26 @@ test_expect_success 'fetch submodule remote of different name from superproject'
 	git -C a-submodule reset --hard HEAD^^ &&
 
 	git -C child pull --no-recurse-submodules &&
-	git -C child submodule update
+	git -C child submodule update &&
+	test_path_is_file child/a-submodule/moreecho.t
+'
+
+test_expect_success 'fetch non-origin submodule remote named different from superproject' '
+	git -C child/a-submodule remote rename origin o2 &&
+
+	# Create commit that is unreachable from current master branch
+	# newmain is already reset in the previous test
+	test_commit -C a-submodule echo_o2 &&
+	test_commit -C a-submodule moreecho_o2 &&
+	subc=$(git -C a-submodule rev-parse --short HEAD) &&
+
+	git -C parent/a-submodule fetch &&
+	git -C parent/a-submodule checkout "$subc" &&
+	git -C parent commit -m "update submodule o2" a-submodule &&
+	git -C a-submodule reset --hard HEAD^^ &&
+
+	git -C child pull --recurse-submodules &&
+	test_path_is_file child/a-submodule/moreecho_o2.t
 '
 
 test_done
diff --git a/t/t7426-submodule-get-default-remote.sh b/t/t7426-submodule-get-default-remote.sh
new file mode 100755
index 0000000000..b842af9a2d
--- /dev/null
+++ b/t/t7426-submodule-get-default-remote.sh
@@ -0,0 +1,186 @@
+#!/bin/sh
+
+test_description='git submodule--helper get-default-remote'
+
+TEST_NO_CREATE_REPO=1
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git config --global protocol.file.allow always
+'
+
+test_expect_success 'setup repositories' '
+	# Create a repository to be used as submodule
+	git init sub &&
+	test_commit --no-tag -C sub "initial commit in sub" file.txt "sub content" &&
+
+	# Create main repository
+	git init super &&
+	(
+		cd super &&
+		mkdir subdir &&
+		test_commit --no-tag -C subdir "initial commit in super" main.txt "super content" &&
+		git submodule add ../sub subpath &&
+		git commit -m "add submodule 'sub' at subpath"
+	)
+'
+
+test_expect_success 'get-default-remote returns origin for initialized submodule' '
+	(
+		cd super &&
+		git submodule update --init &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works from subdirectory' '
+	(
+		cd super/subdir &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote ../subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-existent path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote nonexistent 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-submodule path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subdir 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails without path argument' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with too many arguments' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subpath subdir 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'setup submodule with non-origin default remote name' '
+	# Create another submodule path with a different remote name
+	(
+		cd super &&
+		git submodule add ../sub upstream-subpath &&
+		git commit -m "add second submodule in upstream-subpath" &&
+		git submodule update --init upstream-subpath &&
+
+		# Change the remote name in the submodule
+		cd upstream-subpath &&
+		git remote rename origin upstream
+	)
+'
+
+test_expect_success 'get-default-remote returns non-origin remote name' '
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes' '
+	(
+		cd super/subpath &&
+		git remote add other-upstream ../../sub &&
+		git remote add myfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes and none are origin' '
+	(
+		cd super/upstream-subpath &&
+		git remote add yet-another-upstream ../../sub &&
+		git remote add yourfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'setup nested submodule with non-origin remote' '
+	git init innersub &&
+	test_commit --no-tag -C innersub "initial commit in innersub" inner.txt "innersub content" &&
+
+	(
+		cd sub &&
+		git submodule add ../innersub innersubpath &&
+		git commit -m "add nested submodule at innersubpath"
+	) &&
+
+	(
+		cd super/upstream-subpath &&
+		git pull upstream &&
+		git submodule update --init --recursive . &&
+		(
+			cd innersubpath &&
+			git remote rename origin another_upstream
+		)
+	)
+'
+
+test_expect_success 'get-default-remote works with nested submodule' '
+	(
+		cd super &&
+		echo "another_upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath/innersubpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works with submodule that has no remotes' '
+	# Create a submodule directory manually without remotes
+	(
+		cd super &&
+		git init no-remote-sub &&
+		test_commit --no-tag -C no-remote-sub "local commit" local.txt "local content"
+	) &&
+
+	# Add it as a submodule
+	(
+		cd super &&
+		git submodule add ./no-remote-sub &&
+		git commit -m "add local submodule 'no-remote-sub'"
+	) &&
+
+	(
+		cd super &&
+		# Should fall back to "origin" remote name when no remotes exist
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote no-remote-sub >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_done

builtin/submodule--helper.c, submodule.c, t/meson.build, t/t5526-fetch-submodules.sh, t/t5572-pull-submodule.sh, t/t7426-submodule-get-default-remote.sh

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index b621d14275..0a4676f3ba 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -113,6 +113,43 @@ static int get_default_remote_submodule(const char *module_path, char **default_
 	return 0;
 }
 
+static int module_get_default_remote(int argc, const char **argv, const char *prefix,
+				     struct repository *repo UNUSED)
+{
+	const char *path;
+	char *resolved_path = NULL;
+	char *default_remote = NULL;
+	int code;
+	struct option options[] = {
+		OPT_END()
+	};
+	const char *const usage[] = {
+		N_("git submodule--helper get-default-remote <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	path = argv[0];
+	if (prefix && *prefix && !is_absolute_path(path)) {
+		resolved_path = xstrfmt("%s%s", prefix, path);
+		path = resolved_path;
+	}
+
+	code = get_default_remote_submodule(path, &default_remote);
+	if (code) {
+		free(resolved_path);
+		return code;
+	}
+
+	printf("%s\n", default_remote);
+	free(default_remote);
+	free(resolved_path);
+	return 0;
+}
+
 /* the result should be freed by the caller. */
 static char *get_submodule_displaypath(const char *path, const char *prefix,
 				       const char *super_prefix)
@@ -3788,6 +3825,7 @@ int cmd_submodule__helper(int argc,
 		OPT_SUBCOMMAND("set-url", &fn, module_set_url),
 		OPT_SUBCOMMAND("set-branch", &fn, module_set_branch),
 		OPT_SUBCOMMAND("create-branch", &fn, module_create_branch),
+		OPT_SUBCOMMAND("get-default-remote", &fn, module_get_default_remote),
 		OPT_END()
 	};
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
diff --git a/submodule.c b/submodule.c
index 508938e4da..906febfa0e 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1708,6 +1708,8 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 	if (spf->oid_fetch_tasks_nr) {
 		struct fetch_task *task =
 			spf->oid_fetch_tasks[spf->oid_fetch_tasks_nr - 1];
+		struct child_process cp_remote = CHILD_PROCESS_INIT;
+		struct strbuf remote_name = STRBUF_INIT;
 		spf->oid_fetch_tasks_nr--;
 
 		child_process_init(cp);
@@ -1721,8 +1723,19 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 		strvec_pushf(&cp->args, "--submodule-prefix=%s%s/",
 			     spf->prefix, task->sub->path);
 
-		/* NEEDSWORK: have get_default_remote from submodule--helper */
-		strvec_push(&cp->args, "origin");
+		cp_remote.git_cmd = 1;
+		strvec_pushl(&cp_remote.args, "submodule--helper",
+			     "get-default-remote", task->sub->path, NULL);
+
+		if (!capture_command(&cp_remote, &remote_name, 0)) {
+			strbuf_trim_trailing_newline(&remote_name);
+			strvec_push(&cp->args, remote_name.buf);
+		} else {
+			/* Fallback to "origin" if the helper fails */
+			strvec_push(&cp->args, "origin");
+		}
+		strbuf_release(&remote_name);
+
 		oid_array_for_each_unique(task->commits,
 					  append_oid_to_argv, &cp->args);
 
diff --git a/t/meson.build b/t/meson.build
index 6d91470ebc..cfa3de5962 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -894,6 +894,7 @@ integration_tests = [
   't7423-submodule-symlinks.sh',
   't7424-submodule-mixed-ref-formats.sh',
   't7425-submodule-gitdir-path-extension.sh',
+  't7426-submodule-get-default-remote.sh',
   't7450-bad-git-dotfiles.sh',
   't7500-commit-template-squash-signoff.sh',
   't7501-commit-basic-functionality.sh',
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 5e566205ba..cc8aec5b1c 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -834,11 +834,37 @@ test_expect_success "fetch new submodule commits on-demand outside standard refs
 	git commit -m "updated submodules outside of refs/heads" &&
 	E=$(git rev-parse HEAD) &&
 	git update-ref refs/changes/3 $E &&
+	FETCH_TRACE="$(pwd)/trace.out" &&
+	test_when_finished "rm -f \"$FETCH_TRACE\"" &&
 	(
 		cd downstream &&
-		git fetch --recurse-submodules origin refs/changes/3:refs/heads/my_branch &&
+		DEEP_START=$(git -C submodule/subdir/deepsubmodule rev-parse --short origin/deep) &&
+		DEEP_END=$(git -C "$pwd/deepsubmodule" rev-parse --short deep) &&
+		cat >"expect_fetch" <<-EOF &&
+		From $pwd/.
+		 * [new ref]         refs/changes/3 -> my_branch
+		Fetching submodule sub1
+		Fetching submodule sub1/subdir/deepsubmodule
+		Fetching submodule submodule
+		Fetching submodule submodule/subdir/deepsubmodule
+		From $pwd/deepsubmodule
+		   $DEEP_START..$DEEP_END  deep       -> origin/deep
+		From $pwd/./sub1
+		 * branch            $D -> FETCH_HEAD
+		Fetching submodule sub1/subdir/deepsubmodule
+		From $pwd/submodule
+		 * branch            $C -> FETCH_HEAD
+		Fetching submodule submodule/subdir/deepsubmodule
+		EOF
+		GIT_TRACE="$FETCH_TRACE" git fetch --recurse-submodules origin \
+			refs/changes/3:refs/heads/my_branch 2>actual_fetch &&
+		test_cmp expect_fetch actual_fetch &&
 		git -C submodule cat-file -t $C &&
 		git -C sub1 cat-file -t $D &&
+		test_grep "trace: built-in: git submodule--helper get-default-remote sub1" \
+			"$FETCH_TRACE" &&
+		test_grep "trace: built-in: git fetch .* --submodule-prefix=sub1/ origin" \
+			"$FETCH_TRACE" &&
 		git checkout --recurse-submodules FETCH_HEAD
 	)
 '
@@ -929,6 +955,90 @@ test_expect_success 'fetch new submodule commit intermittently referenced by sup
 	)
 '
 
+test_expect_success 'fetch new submodule commits on-demand outside standard refspec with custom remote name' '
+	# depends on the previous test for setup
+
+	# Rename the remote in sub1 from "origin" to "custom_remote"
+	git -C downstream/sub1 remote rename origin custom_remote &&
+
+	# Create new commits in the original submodules
+	C=$(git -C submodule commit-tree \
+		-m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom1 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree \
+		-m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom2 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit \
+		-m "updated submodules outside of refs/heads for custom remote" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom3 $E &&
+	FETCH_TRACE="$(pwd)/trace.out" &&
+	test_when_finished "rm -f \"$FETCH_TRACE\"" &&
+	(
+		cd downstream &&
+		DEEP_START=$(git -C submodule/subdir/deepsubmodule rev-parse --short \
+			origin/deep) &&
+		DEEP_END=$(git -C "$pwd/deepsubmodule" rev-parse --short deep) &&
+		cat >"expect_fetch_custom" <<-EOF &&
+		From $pwd/.
+		 * [new ref]         refs/changes/custom3 -> my_other_branch
+		Fetching submodule sub1
+		Fetching submodule sub1/subdir/deepsubmodule
+		Fetching submodule submodule
+		Fetching submodule submodule/subdir/deepsubmodule
+		From $pwd/./sub1
+		 * branch            $D -> FETCH_HEAD
+		Fetching submodule sub1/subdir/deepsubmodule
+		From $pwd/submodule
+		 * branch            $C -> FETCH_HEAD
+		Fetching submodule submodule/subdir/deepsubmodule
+		EOF
+		GIT_TRACE="$FETCH_TRACE" git fetch --recurse-submodules origin \
+			refs/changes/custom3:refs/heads/my_other_branch \
+			2>actual_fetch_custom &&
+		# the without .gitmodules test above causes warnings
+		grep -v "^warning: " actual_fetch_custom >actual_fetch_warnings_removed &&
+		test_cmp expect_fetch_custom actual_fetch_warnings_removed &&
+
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		test_grep "trace: built-in: git submodule--helper get-default-remote sub1" \
+			"$FETCH_TRACE" &&
+		test_grep "trace: built-in: git fetch .* --submodule-prefix=sub1/ custom_remote $D" \
+			"$FETCH_TRACE" &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
+test_expect_success 'fetch new submodule commit on-demand in FETCH_HEAD from custom remote' '
+	# depends on the previous test for setup
+
+	C=$(git -C submodule commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom4 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom5 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom6 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom6 &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
 add_commit_push () {
 	dir="$1" &&
 	msg="$2" &&
diff --git a/t/t5572-pull-submodule.sh b/t/t5572-pull-submodule.sh
index 45f384dd32..42d14328b6 100755
--- a/t/t5572-pull-submodule.sh
+++ b/t/t5572-pull-submodule.sh
@@ -257,7 +257,26 @@ test_expect_success 'fetch submodule remote of different name from superproject'
 	git -C a-submodule reset --hard HEAD^^ &&
 
 	git -C child pull --no-recurse-submodules &&
-	git -C child submodule update
+	git -C child submodule update &&
+	test_path_is_file child/a-submodule/moreecho.t
+'
+
+test_expect_success 'fetch non-origin submodule remote named different from superproject' '
+	git -C child/a-submodule remote rename origin o2 &&
+
+	# Create commit that is unreachable from current master branch
+	# newmain is already reset in the previous test
+	test_commit -C a-submodule echo_o2 &&
+	test_commit -C a-submodule moreecho_o2 &&
+	subc=$(git -C a-submodule rev-parse --short HEAD) &&
+
+	git -C parent/a-submodule fetch &&
+	git -C parent/a-submodule checkout "$subc" &&
+	git -C parent commit -m "update submodule o2" a-submodule &&
+	git -C a-submodule reset --hard HEAD^^ &&
+
+	git -C child pull --recurse-submodules &&
+	test_path_is_file child/a-submodule/moreecho_o2.t
 '
 
 test_done
diff --git a/t/t7426-submodule-get-default-remote.sh b/t/t7426-submodule-get-default-remote.sh
new file mode 100755
index 0000000000..b842af9a2d
--- /dev/null
+++ b/t/t7426-submodule-get-default-remote.sh
@@ -0,0 +1,186 @@
+#!/bin/sh
+
+test_description='git submodule--helper get-default-remote'
+
+TEST_NO_CREATE_REPO=1
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git config --global protocol.file.allow always
+'
+
+test_expect_success 'setup repositories' '
+	# Create a repository to be used as submodule
+	git init sub &&
+	test_commit --no-tag -C sub "initial commit in sub" file.txt "sub content" &&
+
+	# Create main repository
+	git init super &&
+	(
+		cd super &&
+		mkdir subdir &&
+		test_commit --no-tag -C subdir "initial commit in super" main.txt "super content" &&
+		git submodule add ../sub subpath &&
+		git commit -m "add submodule 'sub' at subpath"
+	)
+'
+
+test_expect_success 'get-default-remote returns origin for initialized submodule' '
+	(
+		cd super &&
+		git submodule update --init &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works from subdirectory' '
+	(
+		cd super/subdir &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote ../subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-existent path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote nonexistent 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-submodule path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subdir 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails without path argument' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with too many arguments' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subpath subdir 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'setup submodule with non-origin default remote name' '
+	# Create another submodule path with a different remote name
+	(
+		cd super &&
+		git submodule add ../sub upstream-subpath &&
+		git commit -m "add second submodule in upstream-subpath" &&
+		git submodule update --init upstream-subpath &&
+
+		# Change the remote name in the submodule
+		cd upstream-subpath &&
+		git remote rename origin upstream
+	)
+'
+
+test_expect_success 'get-default-remote returns non-origin remote name' '
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes' '
+	(
+		cd super/subpath &&
+		git remote add other-upstream ../../sub &&
+		git remote add myfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes and none are origin' '
+	(
+		cd super/upstream-subpath &&
+		git remote add yet-another-upstream ../../sub &&
+		git remote add yourfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'setup nested submodule with non-origin remote' '
+	git init innersub &&
+	test_commit --no-tag -C innersub "initial commit in innersub" inner.txt "innersub content" &&
+
+	(
+		cd sub &&
+		git submodule add ../innersub innersubpath &&
+		git commit -m "add nested submodule at innersubpath"
+	) &&
+
+	(
+		cd super/upstream-subpath &&
+		git pull upstream &&
+		git submodule update --init --recursive . &&
+		(
+			cd innersubpath &&
+			git remote rename origin another_upstream
+		)
+	)
+'
+
+test_expect_success 'get-default-remote works with nested submodule' '
+	(
+		cd super &&
+		echo "another_upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath/innersubpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works with submodule that has no remotes' '
+	# Create a submodule directory manually without remotes
+	(
+		cd super &&
+		git init no-remote-sub &&
+		test_commit --no-tag -C no-remote-sub "local commit" local.txt "local content"
+	) &&
+
+	# Add it as a submodule
+	(
+		cd super &&
+		git submodule add ./no-remote-sub &&
+		git commit -m "add local submodule 'no-remote-sub'"
+	) &&
+
+	(
+		cd super &&
+		# Should fall back to "origin" remote name when no remotes exist
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote no-remote-sub >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_done

builtin/submodule--helper.c, submodule.c, t/meson.build, t/t5526-fetch-submodules.sh, t/t5572-pull-submodule.sh, t/t7426-submodule-get-default-remote.sh

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index b621d14275..0a4676f3ba 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -113,6 +113,43 @@ static int get_default_remote_submodule(const char *module_path, char **default_
 	return 0;
 }
 
+static int module_get_default_remote(int argc, const char **argv, const char *prefix,
+				     struct repository *repo UNUSED)
+{
+	const char *path;
+	char *resolved_path = NULL;
+	char *default_remote = NULL;
+	int code;
+	struct option options[] = {
+		OPT_END()
+	};
+	const char *const usage[] = {
+		N_("git submodule--helper get-default-remote <path>"),
+		NULL
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+
+	path = argv[0];
+	if (prefix && *prefix && !is_absolute_path(path)) {
+		resolved_path = xstrfmt("%s%s", prefix, path);
+		path = resolved_path;
+	}
+
+	code = get_default_remote_submodule(path, &default_remote);
+	if (code) {
+		free(resolved_path);
+		return code;
+	}
+
+	printf("%s\n", default_remote);
+	free(default_remote);
+	free(resolved_path);
+	return 0;
+}
+
 /* the result should be freed by the caller. */
 static char *get_submodule_displaypath(const char *path, const char *prefix,
 				       const char *super_prefix)
@@ -3788,6 +3825,7 @@ int cmd_submodule__helper(int argc,
 		OPT_SUBCOMMAND("set-url", &fn, module_set_url),
 		OPT_SUBCOMMAND("set-branch", &fn, module_set_branch),
 		OPT_SUBCOMMAND("create-branch", &fn, module_create_branch),
+		OPT_SUBCOMMAND("get-default-remote", &fn, module_get_default_remote),
 		OPT_END()
 	};
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
diff --git a/submodule.c b/submodule.c
index 508938e4da..906febfa0e 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1708,6 +1708,8 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 	if (spf->oid_fetch_tasks_nr) {
 		struct fetch_task *task =
 			spf->oid_fetch_tasks[spf->oid_fetch_tasks_nr - 1];
+		struct child_process cp_remote = CHILD_PROCESS_INIT;
+		struct strbuf remote_name = STRBUF_INIT;
 		spf->oid_fetch_tasks_nr--;
 
 		child_process_init(cp);
@@ -1721,8 +1723,19 @@ static int get_next_submodule(struct child_process *cp, struct strbuf *err,
 		strvec_pushf(&cp->args, "--submodule-prefix=%s%s/",
 			     spf->prefix, task->sub->path);
 
-		/* NEEDSWORK: have get_default_remote from submodule--helper */
-		strvec_push(&cp->args, "origin");
+		cp_remote.git_cmd = 1;
+		strvec_pushl(&cp_remote.args, "submodule--helper",
+			     "get-default-remote", task->sub->path, NULL);
+
+		if (!capture_command(&cp_remote, &remote_name, 0)) {
+			strbuf_trim_trailing_newline(&remote_name);
+			strvec_push(&cp->args, remote_name.buf);
+		} else {
+			/* Fallback to "origin" if the helper fails */
+			strvec_push(&cp->args, "origin");
+		}
+		strbuf_release(&remote_name);
+
 		oid_array_for_each_unique(task->commits,
 					  append_oid_to_argv, &cp->args);
 
diff --git a/t/meson.build b/t/meson.build
index 6d91470ebc..cfa3de5962 100644
--- a/t/meson.build
+++ b/t/meson.build
@@ -894,6 +894,7 @@ integration_tests = [
   't7423-submodule-symlinks.sh',
   't7424-submodule-mixed-ref-formats.sh',
   't7425-submodule-gitdir-path-extension.sh',
+  't7426-submodule-get-default-remote.sh',
   't7450-bad-git-dotfiles.sh',
   't7500-commit-template-squash-signoff.sh',
   't7501-commit-basic-functionality.sh',
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 5e566205ba..1242ee9185 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -834,11 +834,18 @@ test_expect_success "fetch new submodule commits on-demand outside standard refs
 	git commit -m "updated submodules outside of refs/heads" &&
 	E=$(git rev-parse HEAD) &&
 	git update-ref refs/changes/3 $E &&
+	FETCH_TRACE="$(pwd)/trace.out" &&
+	test_when_finished "rm -f \"$FETCH_TRACE\"" &&
 	(
 		cd downstream &&
-		git fetch --recurse-submodules origin refs/changes/3:refs/heads/my_branch &&
+		GIT_TRACE="$FETCH_TRACE" git fetch --recurse-submodules origin \
+			refs/changes/3:refs/heads/my_branch &&
 		git -C submodule cat-file -t $C &&
 		git -C sub1 cat-file -t $D &&
+		test_grep "trace: built-in: git submodule--helper get-default-remote sub1" \
+			"$FETCH_TRACE" &&
+		test_grep "trace: built-in: git fetch .* --submodule-prefix=sub1/ origin" \
+			"$FETCH_TRACE" &&
 		git checkout --recurse-submodules FETCH_HEAD
 	)
 '
@@ -929,6 +936,68 @@ test_expect_success 'fetch new submodule commit intermittently referenced by sup
 	)
 '
 
+test_expect_success 'fetch new submodule commits on-demand outside standard refspec with custom remote name' '
+	# depends on the previous test for setup
+
+	# Rename the remote in sub1 from "origin" to "custom_remote"
+	git -C downstream/sub1 remote rename origin custom_remote &&
+
+	# Create new commits in the original submodules
+	C=$(git -C submodule commit-tree \
+		-m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom1 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree \
+		-m "change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom2 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit \
+		-m "updated submodules outside of refs/heads for custom remote" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom3 $E &&
+	FETCH_TRACE="$(pwd)/trace.out" &&
+	test_when_finished "rm -f \"$FETCH_TRACE\"" &&
+	(
+		cd downstream &&
+		GIT_TRACE="$FETCH_TRACE" git fetch --recurse-submodules origin \
+			refs/changes/custom3:refs/heads/my_other_branch &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		test_grep "trace: built-in: git submodule--helper get-default-remote sub1" \
+			"$FETCH_TRACE" &&
+		test_grep "trace: built-in: git fetch .* --submodule-prefix=sub1/ custom_remote $D" \
+			"$FETCH_TRACE" &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
+test_expect_success 'fetch new submodule commit on-demand in FETCH_HEAD from custom remote' '
+	# depends on the previous test for setup
+
+	C=$(git -C submodule commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C submodule update-ref refs/changes/custom4 $C &&
+	git update-index --cacheinfo 160000 $C submodule &&
+	test_tick &&
+
+	D=$(git -C sub1 commit-tree -m "another change outside refs/heads for custom remote" HEAD^{tree}) &&
+	git -C sub1 update-ref refs/changes/custom5 $D &&
+	git update-index --cacheinfo 160000 $D sub1 &&
+
+	git commit -m "updated submodules outside of refs/heads" &&
+	E=$(git rev-parse HEAD) &&
+	git update-ref refs/changes/custom6 $E &&
+	(
+		cd downstream &&
+		git fetch --recurse-submodules origin refs/changes/custom6 &&
+		git -C submodule cat-file -t $C &&
+		git -C sub1 cat-file -t $D &&
+		git checkout --recurse-submodules FETCH_HEAD
+	)
+'
+
 add_commit_push () {
 	dir="$1" &&
 	msg="$2" &&
diff --git a/t/t5572-pull-submodule.sh b/t/t5572-pull-submodule.sh
index 45f384dd32..42d14328b6 100755
--- a/t/t5572-pull-submodule.sh
+++ b/t/t5572-pull-submodule.sh
@@ -257,7 +257,26 @@ test_expect_success 'fetch submodule remote of different name from superproject'
 	git -C a-submodule reset --hard HEAD^^ &&
 
 	git -C child pull --no-recurse-submodules &&
-	git -C child submodule update
+	git -C child submodule update &&
+	test_path_is_file child/a-submodule/moreecho.t
+'
+
+test_expect_success 'fetch non-origin submodule remote named different from superproject' '
+	git -C child/a-submodule remote rename origin o2 &&
+
+	# Create commit that is unreachable from current master branch
+	# newmain is already reset in the previous test
+	test_commit -C a-submodule echo_o2 &&
+	test_commit -C a-submodule moreecho_o2 &&
+	subc=$(git -C a-submodule rev-parse --short HEAD) &&
+
+	git -C parent/a-submodule fetch &&
+	git -C parent/a-submodule checkout "$subc" &&
+	git -C parent commit -m "update submodule o2" a-submodule &&
+	git -C a-submodule reset --hard HEAD^^ &&
+
+	git -C child pull --recurse-submodules &&
+	test_path_is_file child/a-submodule/moreecho_o2.t
 '
 
 test_done
diff --git a/t/t7426-submodule-get-default-remote.sh b/t/t7426-submodule-get-default-remote.sh
new file mode 100755
index 0000000000..b842af9a2d
--- /dev/null
+++ b/t/t7426-submodule-get-default-remote.sh
@@ -0,0 +1,186 @@
+#!/bin/sh
+
+test_description='git submodule--helper get-default-remote'
+
+TEST_NO_CREATE_REPO=1
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git config --global protocol.file.allow always
+'
+
+test_expect_success 'setup repositories' '
+	# Create a repository to be used as submodule
+	git init sub &&
+	test_commit --no-tag -C sub "initial commit in sub" file.txt "sub content" &&
+
+	# Create main repository
+	git init super &&
+	(
+		cd super &&
+		mkdir subdir &&
+		test_commit --no-tag -C subdir "initial commit in super" main.txt "super content" &&
+		git submodule add ../sub subpath &&
+		git commit -m "add submodule 'sub' at subpath"
+	)
+'
+
+test_expect_success 'get-default-remote returns origin for initialized submodule' '
+	(
+		cd super &&
+		git submodule update --init &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works from subdirectory' '
+	(
+		cd super/subdir &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote ../subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-existent path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote nonexistent 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with non-submodule path' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subdir 2>err &&
+		test_grep "could not get a repository handle" err
+	)
+'
+
+test_expect_success 'get-default-remote fails without path argument' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'get-default-remote fails with too many arguments' '
+	(
+		cd super &&
+		test_must_fail git submodule--helper get-default-remote subpath subdir 2>err &&
+		test_grep "usage:" err
+	)
+'
+
+test_expect_success 'setup submodule with non-origin default remote name' '
+	# Create another submodule path with a different remote name
+	(
+		cd super &&
+		git submodule add ../sub upstream-subpath &&
+		git commit -m "add second submodule in upstream-subpath" &&
+		git submodule update --init upstream-subpath &&
+
+		# Change the remote name in the submodule
+		cd upstream-subpath &&
+		git remote rename origin upstream
+	)
+'
+
+test_expect_success 'get-default-remote returns non-origin remote name' '
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes' '
+	(
+		cd super/subpath &&
+		git remote add other-upstream ../../sub &&
+		git remote add myfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote handles submodule with multiple remotes and none are origin' '
+	(
+		cd super/upstream-subpath &&
+		git remote add yet-another-upstream ../../sub &&
+		git remote add yourfork ../../sub
+	) &&
+
+	(
+		cd super &&
+		echo "upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'setup nested submodule with non-origin remote' '
+	git init innersub &&
+	test_commit --no-tag -C innersub "initial commit in innersub" inner.txt "innersub content" &&
+
+	(
+		cd sub &&
+		git submodule add ../innersub innersubpath &&
+		git commit -m "add nested submodule at innersubpath"
+	) &&
+
+	(
+		cd super/upstream-subpath &&
+		git pull upstream &&
+		git submodule update --init --recursive . &&
+		(
+			cd innersubpath &&
+			git remote rename origin another_upstream
+		)
+	)
+'
+
+test_expect_success 'get-default-remote works with nested submodule' '
+	(
+		cd super &&
+		echo "another_upstream" >expect &&
+		git submodule--helper get-default-remote upstream-subpath/innersubpath >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get-default-remote works with submodule that has no remotes' '
+	# Create a submodule directory manually without remotes
+	(
+		cd super &&
+		git init no-remote-sub &&
+		test_commit --no-tag -C no-remote-sub "local commit" local.txt "local content"
+	) &&
+
+	# Add it as a submodule
+	(
+		cd super &&
+		git submodule add ./no-remote-sub &&
+		git commit -m "add local submodule 'no-remote-sub'"
+	) &&
+
+	(
+		cd super &&
+		# Should fall back to "origin" remote name when no remotes exist
+		echo "origin" >expect &&
+		git submodule--helper get-default-remote no-remote-sub >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_done