Keep system probe failures distinct from incompatibility

Treat CLI spawn errors as inconclusive rather than proof of missing capabilities. Verified the CLI discovery suite and git diff --check.

desktop/src/agents/cli/cli-discovery.cjs

@@ -465,11 +465,12 @@ async function probeAgentCapabilities(kind, executable, options = {}) {
         const timedOut = error?.killed === true || error?.code === 'ETIMEDOUT'
         if (timedOut && timeout === 8000) continue
         const diagnostic = `${error?.stdout || ''}\n${error?.stderr || ''}\n${error?.message || ''}`
-        return { probe, error: true, timedOut, authRequired: authFailureCertainty(diagnostic) === 'definitive' }
+        return { probe, error: true, timedOut, systemError: typeof error?.code === 'string' && !timedOut,
+          authRequired: authFailureCertainty(diagnostic) === 'definitive' }
       }
     }
   }))
-  const failed = results.find(result => !result.timedOut && !result.authRequired && (result.error
+  const failed = results.find(result => !result.timedOut && !result.systemError && !result.authRequired && (result.error
     || result.probe.requiredText.some(value => !result.output.includes(value))
     || (result.probe.validateOutput && !result.probe.validateOutput(result.output))))
   if (failed) capabilityCache.delete(cacheKey)
@@ -492,6 +493,11 @@ async function probeAgentCapabilities(kind, executable, options = {}) {
       }
     }
     if (result.timedOut) continue
+    if (result.systemError && !failed) {
+      return { compatibilityState: 'unknown', incompatibilityReason: 'LOCAL_AGENT_CAPABILITY_PROBE_FAILED',
+        incompatibilityProbe: probe.id }
+    }
+    if (result.systemError) continue
     if (result.error) {
       return {
         compatibilityState: 'incompatible',

desktop/test/agents/cli/cli-adapters-discovery.test.cjs

@@ -164,6 +164,16 @@ test('capability timeouts retry once and remain inconclusive when both attempts
   }
 })
 
+test('capability probes do not treat operating system spawn failures as missing features', async () => {
+  for (const code of ['EACCES', 'ENOENT', 'EAGAIN']) {
+    const result = await probeAgentCapabilities('workbuddy', '/test/unavailable-workbuddy', {
+      env: {}, execFileFn: async () => { throw Object.assign(new Error('spawn failed'), { code }) },
+    })
+    assert.equal(result.compatibilityState, 'unknown', code)
+    assert.equal(result.incompatibilityReason, 'LOCAL_AGENT_CAPABILITY_PROBE_FAILED', code)
+  }
+})
+
 function argsForProbe(_command, args) {
   return args.includes('--mode')
     ? '{"type":"session","version":3,"id":"probe-session"}'