Add fork context hint to workflow failure conclusion messages (#18529)

* Initial plan

* Add fork context hint to workflow failure conclusion messages

When a gh-aw workflow fails in a fork repository, append a hint to
the failure issue/comment body explaining that secrets from the parent
repository are not inherited.

- Add buildForkContextHint() in handle_agent_failure.cjs that checks
  context.payload?.repository?.fork using optional chaining
- Add fork_context to templateContext for both new issue creation and
  existing issue comment paths
- Update agent_failure_issue.md and agent_failure_comment.md templates
  to include the {fork_context} placeholder

Closes part of #18481

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Author: Copilot

actions/setup/js/handle_agent_failure.cjs

@@ -290,6 +290,17 @@ function buildCreateDiscussionErrorsContext(createDiscussionErrors) {
   return context;
 }
 
+/**
+ * Build a fork context hint string when the repository is a fork.
+ * @returns {string} Fork hint string, or empty string if not a fork
+ */
+function buildForkContextHint() {
+  if (context.payload?.repository?.fork) {
+    return "\n💡 **This repository is a fork.** If this failure is due to missing API keys or tokens, note that secrets from the parent repository are not inherited. Configure the required secrets directly in your fork's Settings → Secrets and variables → Actions.\n";
+  }
+  return "";
+}
+
 /**
  * Build a context string describing code-push failures for inclusion in failure issue/comment bodies.
  * @param {string} codePushFailureErrors - Newline-separated list of "type:error" entries
@@ -617,6 +628,9 @@ async function main() {
           missingSafeOutputsContext += "- The agent should have called `noop` to explicitly indicate no action was taken\n\n";
         }
 
+        // Build fork context hint
+        const forkContext = buildForkContextHint();
+
         // Create template context
         const templateContext = {
           run_url: runUrl,
@@ -635,6 +649,7 @@ async function main() {
           repo_memory_validation_context: repoMemoryValidationContext,
           missing_data_context: missingDataContext,
           missing_safe_outputs_context: missingSafeOutputsContext,
+          fork_context: forkContext,
         };
 
         // Render the comment template
@@ -725,6 +740,9 @@ async function main() {
           missingSafeOutputsContext += "- The agent should have called `noop` to explicitly indicate no action was taken\n\n";
         }
 
+        // Build fork context hint
+        const forkContext = buildForkContextHint();
+
         // Create template context with sanitized workflow name
         const templateContext = {
           workflow_name: sanitizedWorkflowName,
@@ -744,6 +762,7 @@ async function main() {
           repo_memory_validation_context: repoMemoryValidationContext,
           missing_data_context: missingDataContext,
           missing_safe_outputs_context: missingSafeOutputsContext,
+          fork_context: forkContext,
         };
 
         // Render the issue template

actions/setup/md/agent_failure_comment.md

@@ -1,3 +1,3 @@
 Agent job [{run_id}]({run_url}) failed.
 
-{secret_verification_context}{assignment_errors_context}{create_discussion_errors_context}{code_push_failure_context}{repo_memory_validation_context}{missing_data_context}{missing_safe_outputs_context}
+{secret_verification_context}{assignment_errors_context}{create_discussion_errors_context}{code_push_failure_context}{repo_memory_validation_context}{missing_data_context}{missing_safe_outputs_context}{fork_context}

actions/setup/md/agent_failure_issue.md

@@ -4,7 +4,7 @@
 **Branch:** {branch}  
 **Run:** {run_url}{pull_request_info}
 
-{secret_verification_context}{assignment_errors_context}{create_discussion_errors_context}{code_push_failure_context}{repo_memory_validation_context}{missing_data_context}{missing_safe_outputs_context}
+{secret_verification_context}{assignment_errors_context}{create_discussion_errors_context}{code_push_failure_context}{repo_memory_validation_context}{missing_data_context}{missing_safe_outputs_context}{fork_context}
 
 ### Action Required