From 00792c7ba32d1415f7f6e99e807a1e8312aecf67 Mon Sep 17 00:00:00 2001
From: Matthijs Berends <31037261+msberends@users.noreply.github.com>
Date: Fri, 6 Jun 2025 09:20:07 +0200
Subject: [PATCH 1/3] Update action.yml

---
 setup-r/action.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/setup-r/action.yml b/setup-r/action.yml
index 936b2c53..e20678d1 100644
--- a/setup-r/action.yml
+++ b/setup-r/action.yml
@@ -65,7 +65,7 @@ inputs:
       Windows.'
     default: false
   extra-repositories:
-    description: 'One or more extra CRAN-like repositories to include in the `repos` global option'
+    description: 'One or more extra CRAN-like repositories to include in the `repos` global option. This must be a single character; multiple repos can be set using a comma: "https://repo1.org, https://repo2.org".'
     default: ''
   working-directory:
     description: >

From b4736c63cc905129cfc526110ffc2aad5c635db3 Mon Sep 17 00:00:00 2001
From: Matthijs Berends <31037261+msberends@users.noreply.github.com>
Date: Fri, 6 Jun 2025 13:03:00 +0200
Subject: [PATCH 2/3] Update action.yml

---
 setup-r/action.yml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/setup-r/action.yml b/setup-r/action.yml
index e20678d1..8fe0fef1 100644
--- a/setup-r/action.yml
+++ b/setup-r/action.yml
@@ -65,7 +65,9 @@ inputs:
       Windows.'
     default: false
   extra-repositories:
-    description: 'One or more extra CRAN-like repositories to include in the `repos` global option. This must be a single character; multiple repos can be set using a comma: "https://repo1.org, https://repo2.org".'
+    description: 'One or more extra CRAN-like repositories to include in the `repos` global
+    option. This can be a single character (e.g., "https://repo1.org, https://repo2.org") or
+    mutiple characters on separate lines.'
     default: ''
   working-directory:
     description: >

From 4baf6d72dbc8e3d0b6a9194e2298135dcc7825bb Mon Sep 17 00:00:00 2001
From: Matthijs Berends <31037261+msberends@users.noreply.github.com>
Date: Fri, 6 Jun 2025 13:10:21 +0200
Subject: [PATCH 3/3] Update installer.ts

---
 setup-r/src/installer.ts | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/setup-r/src/installer.ts b/setup-r/src/installer.ts
index 85356903..1446405d 100644
--- a/setup-r/src/installer.ts
+++ b/setup-r/src/installer.ts
@@ -703,16 +703,19 @@ async function setupRLibrary(version: IRVersion) {
         : `"${core.getInput("http-user-agent")}"`;
   }
 
-  // Split the repositories by whitespace and then quote each entry joining with commas
-  let extra_repositories = core.getInput("extra-repositories");
 
-  // Prepend a , if there are extra repositories
-  if (extra_repositories) {
+  // Read multiline input which supports both YAML list and comma-separated string
+  let extra_repositories = core.getMultilineInput("extra-repositories", { trimWhitespace: true });
+
+  if (extra_repositories.length > 0) {
     extra_repositories = extra_repositories
-      .split(/\s+/)
-      .map((x) => `"${x}"`)
+      .flatMap((x) => x.split(/\s*,\s*/)) // split comma-separated lines if any
+      .filter((x) => x.length > 0)        // remove empty strings
+      .map((x) => `"${x}"`)               // quote each
       .join(",");
     extra_repositories = ",\n    " + extra_repositories;
+  } else {
+    extra_repositories = "";
   }
 
   await fs.promises.writeFile(