Fix runtime-import path duplication when repo is named .github (#19518)

* Initial plan

* fix: use LastIndex to find .github/ directory when repo is named .github

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

pkg/workflow/compiler_yaml.go

@@ -391,9 +391,12 @@ func (c *Compiler) generatePrompt(yaml *strings.Builder, data *WorkflowData, pre
 		normalizedPath := filepath.ToSlash(c.markdownPath)
 
 		// Look for "/.github/" as a directory (not just substring in repo name like "username.github.io")
-		// We need to match the directory component, not arbitrary substrings
+		// We need to match the directory component, not arbitrary substrings.
+		// Use LastIndex so that when the repo itself is named ".github" (path like
+		// "/root/.github/.github/workflows/file.md"), we find the actual .github
+		// workflows directory rather than the repo root directory.
 		githubDirPattern := "/.github/"
-		githubIndex := strings.Index(normalizedPath, githubDirPattern)
+		githubIndex := strings.LastIndex(normalizedPath, githubDirPattern)
 
 		if githubIndex != -1 {
 			// Extract everything from ".github/" onwards (inclusive)

pkg/workflow/compiler_yaml_test.go

@@ -1142,6 +1142,12 @@ func TestRuntimeImportPathGitHubIO(t *testing.T) {
 			expected:    "{{#runtime-import .github/workflows/workflow.md}}",
 			description: "Normal repo without .github.io should work as before",
 		},
+		{
+			name:        "repo_named_dot_github",
+			repoName:    ".github",
+			expected:    "{{#runtime-import .github/workflows/test.md}}",
+			description: "Repo named '.github' should not duplicate .github in runtime-import path",
+		},
 		{
 			name:        "repo_with_github_in_name",
 			repoName:    "my-github-project",