fix: handle multi-source ArgoCD applications

src/components/-applications/application-card.tsx

@@ -80,15 +80,31 @@ export function ApplicationCard({ app }: ApplicationCardProps) {
         </div>
       </div>
 
-      {/* Repository */}
-      <div className="flex items-center gap-1.5 text-xs text-muted-foreground mb-3 px-3">
-        {formatRepoUrl(app.spec.source.repoURL).isGithub ? (
-          <IconBrandGithubFill size={12} className="text-muted-foreground" />
-        ) : (
-          <IconCodeBranch size={12} className="text-muted-foreground" />
-        )}
-        <span className="truncate">{formatRepoUrl(app.spec.source.repoURL).displayText}</span>
-      </div>
+      {/* Repository - single source */}
+      {app.spec.source && (
+        <div className="flex items-center gap-1.5 text-xs text-muted-foreground mb-3 px-3">
+          {formatRepoUrl(app.spec.source.repoURL).isGithub ? (
+            <IconBrandGithubFill size={12} className="text-muted-foreground" />
+          ) : (
+            <IconCodeBranch size={12} className="text-muted-foreground" />
+          )}
+          <span className="truncate">{formatRepoUrl(app.spec.source.repoURL).displayText}</span>
+        </div>
+      )}
+      {/* Repository - multi-source */}
+      {!app.spec.source && app.spec.sources && app.spec.sources.length > 0 && (
+        <div className="flex items-center gap-1.5 text-xs text-muted-foreground mb-3 px-3">
+          {formatRepoUrl(app.spec.sources[0].repoURL).isGithub ? (
+            <IconBrandGithubFill size={12} className="text-muted-foreground" />
+          ) : (
+            <IconCodeBranch size={12} className="text-muted-foreground" />
+          )}
+          <span className="truncate">
+            {formatRepoUrl(app.spec.sources[0].repoURL).displayText}
+            {app.spec.sources.length > 1 && ` +${app.spec.sources.length - 1} more`}
+          </span>
+        </div>
+      )}
 
       {/* Footer */}
       <div className="flex items-center justify-between border-t border-border p-3">

src/lib/defensive-checks.test.ts

@@ -0,0 +1,214 @@
+import { describe, it, expect } from 'vitest'
+import type { Application } from '@/types/api'
+
+/**
+ * Tests for defensive null checks to prevent runtime errors
+ * when rendering applications with missing or incomplete data
+ */
+describe('Application defensive checks', () => {
+  describe('app.spec.source', () => {
+    it('should handle missing app.spec.source gracefully', () => {
+      const appWithoutSource = {
+        metadata: { name: 'test-app', namespace: 'argocd' },
+        spec: {
+          destination: { namespace: 'default', server: 'https://kubernetes.default.svc' },
+          project: 'default'
+        }
+      } as Application
+
+      // This should not throw - defensive check pattern
+      expect(appWithoutSource.spec.source).toBeUndefined()
+
+      // Optional chaining also safe
+      expect(appWithoutSource.spec.source?.repoURL).toBeUndefined()
+    })
+
+    it('should access source.repoURL when source exists', () => {
+      const appWithSource = {
+        metadata: { name: 'test-app', namespace: 'argocd' },
+        spec: {
+          source: {
+            repoURL: 'https://github.com/test/repo.git',
+            path: 'manifests',
+            targetRevision: 'HEAD'
+          },
+          destination: { namespace: 'default', server: 'https://kubernetes.default.svc' },
+          project: 'default'
+        }
+      } as Application
+
+      if (appWithSource.spec.source) {
+        expect(appWithSource.spec.source.repoURL).toBe('https://github.com/test/repo.git')
+        expect(appWithSource.spec.source.path).toBe('manifests')
+        expect(appWithSource.spec.source.targetRevision).toBe('HEAD')
+      }
+    })
+
+    it('should handle missing targetRevision using optional chaining', () => {
+      const appWithoutRevision = {
+        metadata: { name: 'test-app', namespace: 'argocd' },
+        spec: {
+          source: {
+            repoURL: 'https://github.com/test/repo.git',
+            path: 'manifests'
+          },
+          destination: { namespace: 'default' },
+          project: 'default'
+        }
+      } as Application
+
+      // Optional chaining (?.) prevents errors
+      expect(appWithoutRevision.spec.source?.targetRevision).toBeUndefined()
+      expect(appWithoutRevision.spec.source?.repoURL).toBe('https://github.com/test/repo.git')
+    })
+  })
+
+  describe('Multi-source applications (ArgoCD 2.6+)', () => {
+    it('should handle apps with sources[] instead of source', () => {
+      const multiSourceApp = {
+        metadata: { name: 'test-app', namespace: 'argocd' },
+        spec: {
+          sources: [
+            { repoURL: 'https://github.com/test/repo1.git', path: 'app' },
+            { repoURL: 'https://github.com/test/repo2.git', path: 'config' }
+          ],
+          destination: { namespace: 'default' },
+          project: 'default'
+        }
+      } as Application
+
+      // source is undefined, sources has values
+      expect(multiSourceApp.spec.source).toBeUndefined()
+      expect(multiSourceApp.spec.sources).toHaveLength(2)
+      expect(multiSourceApp.spec.sources?.[0]?.repoURL).toBe('https://github.com/test/repo1.git')
+    })
+
+    it('should gracefully skip rendering when both source and sources are missing', () => {
+      const appWithNeither = {
+        metadata: { name: 'test-app', namespace: 'argocd' },
+        spec: {
+          destination: { namespace: 'default' },
+          project: 'default'
+        }
+      } as Application
+
+      expect(appWithNeither.spec.source).toBeUndefined()
+      expect(appWithNeither.spec.sources).toBeUndefined()
+
+      // Component should skip rendering repository section
+      const shouldRenderRepo = !!(appWithNeither.spec.source || appWithNeither.spec.sources)
+      expect(shouldRenderRepo).toBe(false)
+    })
+
+    it('should display first source and count for multi-source apps in card view', () => {
+      const multiSourceApp = {
+        metadata: { name: 'multi-app', namespace: 'argocd' },
+        spec: {
+          sources: [
+            { repoURL: 'https://github.com/org/repo1.git', path: 'app' },
+            { repoURL: 'https://github.com/org/repo2.git', path: 'config' },
+            { repoURL: 'https://github.com/org/repo3.git', path: 'values' }
+          ],
+          destination: { namespace: 'default' },
+          project: 'default'
+        }
+      } as Application
+
+      // Card view logic: show first source + count
+      const sources = multiSourceApp.spec.sources!
+      const firstSource = sources[0]
+      const additionalCount = sources.length - 1
+
+      expect(firstSource.repoURL).toBe('https://github.com/org/repo1.git')
+      expect(additionalCount).toBe(2)
+
+      // Expected display: "org/repo1 +2 more"
+      const displayText = `${firstSource.repoURL} +${additionalCount} more`
+      expect(displayText).toContain('+2 more')
+    })
+
+    it('should display all sources in detail view sidebar', () => {
+      const multiSourceApp = {
+        metadata: { name: 'multi-app', namespace: 'argocd' },
+        spec: {
+          sources: [
+            { repoURL: 'https://github.com/org/helm-charts.git', chart: 'my-app', targetRevision: '1.0.0' },
+            { repoURL: 'https://github.com/org/config.git', path: 'envs/prod', targetRevision: 'main' }
+          ],
+          destination: { namespace: 'production' },
+          project: 'default'
+        }
+      } as Application
+
+      // Detail view logic: iterate all sources
+      const sources = multiSourceApp.spec.sources!
+
+      expect(sources).toHaveLength(2)
+      expect(sources[0].repoURL).toBe('https://github.com/org/helm-charts.git')
+      expect(sources[0].chart).toBe('my-app')
+      expect(sources[0].targetRevision).toBe('1.0.0')
+      expect(sources[1].repoURL).toBe('https://github.com/org/config.git')
+      expect(sources[1].path).toBe('envs/prod')
+      expect(sources[1].targetRevision).toBe('main')
+    })
+
+    it('should handle single-item sources array', () => {
+      const singleSourceInArray = {
+        metadata: { name: 'single-in-array', namespace: 'argocd' },
+        spec: {
+          sources: [
+            { repoURL: 'https://github.com/test/repo.git', path: 'manifests' }
+          ],
+          destination: { namespace: 'default' },
+          project: 'default'
+        }
+      } as Application
+
+      expect(singleSourceInArray.spec.source).toBeUndefined()
+      expect(singleSourceInArray.spec.sources).toHaveLength(1)
+
+      // Should not show "+0 more" for single source
+      const additionalCount = singleSourceInArray.spec.sources!.length - 1
+      expect(additionalCount).toBe(0)
+    })
+
+    it('should handle empty sources array', () => {
+      const emptySourcesApp = {
+        metadata: { name: 'empty-sources', namespace: 'argocd' },
+        spec: {
+          sources: [],
+          destination: { namespace: 'default' },
+          project: 'default'
+        }
+      } as Application
+
+      expect(emptySourcesApp.spec.sources).toHaveLength(0)
+
+      // Should not render repository section for empty sources
+      const shouldRenderMultiSource = !emptySourcesApp.spec.source &&
+        emptySourcesApp.spec.sources &&
+        emptySourcesApp.spec.sources.length > 0
+      expect(shouldRenderMultiSource).toBe(false)
+    })
+  })
+
+  describe('Loading states and race conditions', () => {
+    it('should handle partially loaded application data', () => {
+      const partialApp = {
+        metadata: { name: 'loading-app', namespace: 'argocd' },
+        spec: {
+          destination: { namespace: 'default' },
+          project: 'default'
+        }
+        // source may arrive later due to API streaming/pagination
+      } as Application
+
+      // Safe access pattern should not throw
+      const hasSource = !!partialApp.spec.source
+      expect(hasSource).toBe(false)
+
+      // Even if we try to access, it won't crash with optional chaining
+      expect(partialApp.spec.source?.repoURL).toBeUndefined()
+    })
+  })
+})

src/routes/_authenticated/applications.$name.tsx

@@ -424,21 +424,43 @@ function ApplicationDetailLayout() {
             <div className="text-sm break-all">{app.spec.destination.server || app.spec.destination.name || 'unknown'}</div>
           </div>
 
-          {/* Repository */}
-          <div>
-            <div className="text-xs font-medium text-muted-foreground mb-1">Repository</div>
-            <div className="flex items-center gap-1.5 text-sm break-all">
-              {formatRepoUrl(app.spec.source.repoURL).isGithub ? (
-                <IconBrandGithubFill size={14} className="flex-shrink-0" />
-              ) : (
-                <IconCodeBranch size={14} className="flex-shrink-0" />
-              )}
-              <span>{formatRepoUrl(app.spec.source.repoURL).displayText}</span>
+          {/* Repository - single source */}
+          {app.spec.source && (
+            <div>
+              <div className="text-xs font-medium text-muted-foreground mb-1">Repository</div>
+              <div className="flex items-center gap-1.5 text-sm break-all">
+                {formatRepoUrl(app.spec.source.repoURL).isGithub ? (
+                  <IconBrandGithubFill size={14} className="flex-shrink-0" />
+                ) : (
+                  <IconCodeBranch size={14} className="flex-shrink-0" />
+                )}
+                <span>{formatRepoUrl(app.spec.source.repoURL).displayText}</span>
+              </div>
             </div>
-          </div>
+          )}
+          {/* Repository - multi-source */}
+          {!app.spec.source && app.spec.sources && app.spec.sources.length > 0 && (
+            <div>
+              <div className="text-xs font-medium text-muted-foreground mb-1">
+                Repositories ({app.spec.sources.length})
+              </div>
+              <div className="space-y-2">
+                {app.spec.sources.map((source, i) => (
+                  <div key={i} className="flex items-center gap-1.5 text-sm break-all">
+                    {formatRepoUrl(source.repoURL).isGithub ? (
+                      <IconBrandGithubFill size={14} className="flex-shrink-0" />
+                    ) : (
+                      <IconCodeBranch size={14} className="flex-shrink-0" />
+                    )}
+                    <span>{formatRepoUrl(source.repoURL).displayText}</span>
+                  </div>
+                ))}
+              </div>
+            </div>
+          )}
 
-          {/* Target revision */}
-          {app.spec.source.targetRevision && (
+          {/* Target revision - single source */}
+          {app.spec.source?.targetRevision && (
             <div>
               <div className="text-sm font-medium text-muted-foreground mb-1">Target revision</div>
               <div className="text-sm font-mono">{app.spec.source.targetRevision}</div>

src/types/api.ts

@@ -22,7 +22,8 @@ export interface Application {
 }
 
 export interface ApplicationSpec {
-  source: ApplicationSource
+  source?: ApplicationSource
+  sources?: ApplicationSource[]
   destination: ApplicationDestination
   project: string
   syncPolicy?: SyncPolicy