fix: trim and validate platformTag, remove misleading platform from example

- Trim platformTag input and reject values containing whitespace or
  commas with a clear error message.
- Remove platform from the native matrix example since it is ignored
  when platformTag is set.

Author: tgenov

azdo-task/DevcontainersCi/src/main.ts

@@ -26,7 +26,16 @@ export async function runMain(): Promise<void> {
 		task.setTaskVariable('hasRunMain', 'true');
 
 		const mergeTag = task.getInput('mergeTag');
-		const platformTag = task.getInput('platformTag');
+		const rawPlatformTag = task.getInput('platformTag');
+		const platformTag = rawPlatformTag?.trim() || undefined;
+
+		if (platformTag && /[\s,]/.test(platformTag)) {
+			task.setResult(
+				task.TaskResult.Failed,
+				`Invalid platformTag '${platformTag}' - must not contain whitespace or commas. Use mergeTag to specify multiple platforms.`,
+			);
+			return;
+		}
 
 		if (mergeTag && platformTag) {
 			task.setResult(

docs/multi-platform-builds.md

@@ -92,10 +92,8 @@ jobs:
       matrix:
         include:
           - runner: ubuntu-latest
-            platform: linux/amd64
             platformTag: linux-amd64
           - runner: ubuntu-24.04-arm
-            platform: linux/arm64
             platformTag: linux-arm64
     runs-on: ${{ matrix.runner }}
     steps:
@@ -109,7 +107,6 @@ jobs:
       - uses: devcontainers/[email protected]
         with:
           imageName: ghcr.io/example/myimage
-          platform: ${{ matrix.platform }}
           platformTag: ${{ matrix.platformTag }}
           push: always
 

github-action/dist/index.js

@@ -2166,7 +2166,11 @@ function runMain() {
             core.info('Starting...');
             core.saveState('hasRunMain', 'true');
             const mergeTag = emptyStringAsUndefined(core.getInput('mergeTag'));
-            const platformTag = emptyStringAsUndefined(core.getInput('platformTag'));
+            const platformTag = emptyStringAsUndefined(core.getInput('platformTag').trim());
+            if (platformTag && /[\s,]/.test(platformTag)) {
+                core.setFailed(`Invalid platformTag '${platformTag}' - must not contain whitespace or commas. Use mergeTag to specify multiple platforms.`);
+                return;
+            }
             if (mergeTag && platformTag) {
                 core.setFailed('mergeTag and platformTag cannot be used together - mergeTag is for the manifest merge job, platformTag is for per-platform build jobs');
                 return;

github-action/dist/index.js.map

@@ -36,7 +36,16 @@ export async function runMain(): Promise<void> {
 		core.saveState('hasRunMain', 'true');
 
 		const mergeTag = emptyStringAsUndefined(core.getInput('mergeTag'));
-		const platformTag = emptyStringAsUndefined(core.getInput('platformTag'));
+		const platformTag = emptyStringAsUndefined(
+			core.getInput('platformTag').trim(),
+		);
+
+		if (platformTag && /[\s,]/.test(platformTag)) {
+			core.setFailed(
+				`Invalid platformTag '${platformTag}' - must not contain whitespace or commas. Use mergeTag to specify multiple platforms.`,
+			);
+			return;
+		}
 
 		if (mergeTag && platformTag) {
 			core.setFailed(