diff --git a/ai/ai-review-agent-gemini-1.0.groovy b/ai/ai-review-agent-gemini-1.0.groovy
index 0dcd157..2c89715 100644
--- a/ai/ai-review-agent-gemini-1.0.groovy
+++ b/ai/ai-review-agent-gemini-1.0.groovy
@@ -19,6 +19,7 @@
 import com.google.inject.*
 
 import org.apache.http.*
+import org.apache.http.client.methods.HttpPost
 import org.apache.http.message.*
 import org.apache.http.entity.StringEntity
 
@@ -29,9 +30,16 @@
 @Singleton
 class AiGeminiReviewProvider implements AiReviewProvider {
     private static final FluentLogger logger = FluentLogger.forEnclosingClass()
-    private static final String GEMINI_API_URL_BASE = 'https://generativelanguage.googleapis.com/v1/models'
+    // v1beta is intended for all calls (models listing, countTokens and generateContent):
+    // preview models and the `-latest` aliases are not exposed on v1 and fail there with 404.
+    private static final String GEMINI_API_URL_BASE = 'https://generativelanguage.googleapis.com/v1beta/models'
     private static final String API_KEY_HEADER = 'x-goog-api-key'
     private static final int MAX_ERROR_LEN = 500
+    // Gemini variants that are not suitable for a text-only code review chat.
+    private static final def NON_CHAT_MODEL =
+            ~/-(image|tts|transcribe|live|custom-?tools)\b|robotics|computer-use|omni|nano-banana/
+    private static final def LATEST_ALIAS = ~/^gemini-(.+)-latest$/
+    private static final def MODEL_VERSION = ~/^gemini-(\d+(?:\.\d+)*)-/
 
     final String displayName = 'Gemini'
 
@@ -40,8 +48,10 @@
 
     @Override
     Set<String> getModels(String apiKey) {
+        Set<String> listed
         try {
-            http.get(GEMINI_API_URL_BASE,
+            // Default page size (50) is smaller than the v1beta catalog.
+            listed = http.get("${GEMINI_API_URL_BASE}?pageSize=1000",
                     [http.acceptApplicationJson(), apiKeyHeader(apiKey)] as Header[],
                     { extractErrorMessage(it) },
                     { extractModels(it) })
@@ -49,6 +59,36 @@
             logger.atWarning().withCause(e).log('Failed to call Gemini API to fetch models')
             return [] as Set
         }
+
+        def available = listed.findAll { isAvailable(apiKey, it) }
+        if (!available) {
+            logger.atWarning().log('None of the Gemini models listed for this key is available')
+        }
+        new LinkedHashSet<>(available.sort(false) { a, b -> compareModels(a, b) })
+    }
+
+    /**
+     * ListModels also returns models that are retired for new users and fail with HTTP 404 on
+     * generateContent. countTokens fails the same way but does not consume generation quota.
+     * Any other failure (quota, network) keeps the model listed.
+     */
+    private boolean isAvailable(String apiKey, String model) {
+        def request = new HttpPost("${GEMINI_API_URL_BASE}/${model}:countTokens")
+        request.setHeaders([http.contentTypeApplicationJson(), apiKeyHeader(apiKey)] as Header[])
+        request.setEntity(new StringEntity(new JsonBuilder([contents: [[parts: [[text: 'ping']]]]]).toString(),
+                StandardCharsets.UTF_8))
+        try {
+            http.execute(request,
+                    { it != HttpStatus.SC_NOT_FOUND } as StatusCodeHandler,
+                    { extractErrorMessage(it) },
+                    { true })
+        } catch (AiCodeReviewException e) {
+            logger.atInfo().log('Gemini model %s is not available: %s', model, e.message)
+            false
+        } catch (IOException e) {
+            logger.atWarning().withCause(e).log('Failed to check availability of Gemini model %s', model)
+            true
+        }
     }
 
     @Override
@@ -76,7 +116,7 @@
         def fetchedModels = json.models?.findAll {
             it.supportedGenerationMethods?.contains('generateContent') &&
                     it.name?.startsWith('models/gemini')
-        }?.collect { it.name.replace('models/', '') } as Set
+        }?.collect { it.name.replace('models/', '') }?.findAll { !(it =~ NON_CHAT_MODEL) } as Set
 
         if (!fetchedModels) {
             logger.atWarning().log("Gemini did not return any model enabled for this key")
@@ -86,6 +126,41 @@
         }
     }
 
+    /**
+     * `-latest` aliases first, then newest version first; within a version pro, flash, flash-lite,
+     * with stable models before previews.
+     */
+    private static int compareModels(String a, String b) {
+        boolean aLatest = a ==~ LATEST_ALIAS
+        boolean bLatest = b ==~ LATEST_ALIAS
+        if (aLatest != bLatest) return aLatest ? -1 : 1
+        int byVersion = compareVersions(versionOf(b), versionOf(a))
+        if (byVersion != 0) return byVersion
+        int byTier = tierOf(a) <=> tierOf(b)
+        if (byTier != 0) return byTier
+        int byPreview = a.contains('-preview') <=> b.contains('-preview')
+        byPreview != 0 ? byPreview : a <=> b
+    }
+
+    private static List<Integer> versionOf(String model) {
+        def matcher = model =~ MODEL_VERSION
+        matcher.find() ? matcher.group(1).tokenize('.').collect { it as int } : []
+    }
+
+    private static int compareVersions(List<Integer> a, List<Integer> b) {
+        for (int i = 0; i < Math.max(a.size(), b.size()); i++) {
+            int byPart = (i < a.size() ? a[i] : 0) <=> (i < b.size() ? b[i] : 0)
+            if (byPart != 0) return byPart
+        }
+        a.size() <=> b.size()
+    }
+
+    private static int tierOf(String model) {
+        if (model.contains('-pro')) return 0
+        if (model.contains('-flash-lite')) return 2
+        model.contains('-flash') ? 1 : 3
+    }
+
     private static String extractResponseText(String body) {
         def json = new JsonSlurper().parseText(body)
 
diff --git a/ai/ai-review-agent-openrouter-1.0.groovy b/ai/ai-review-agent-openrouter-1.0.groovy
index 7cf579d..4b504ed 100644
--- a/ai/ai-review-agent-openrouter-1.0.groovy
+++ b/ai/ai-review-agent-openrouter-1.0.groovy
@@ -200,12 +200,26 @@
     private static String extractErrorMessage(String body) {
         try {
             def json = new JsonSlurper().parseText(body)
-            if (json?.error) return "[${json.error.code}] ${json.error.message}"
+            if (json?.error) {
+                def message = json.error.message as String
+                def detail = formatErrorMetadata(json.error.metadata)
+                return detail ? "${message}: ${detail}" : message
+            }
         } catch (Exception e) {
             logger.atWarning().withCause(e).log('Failed to parse error response')
         }
         return body.length() > MAX_ERROR_LEN ? "${body.take(MAX_ERROR_LEN)}..." : body
     }
+
+    // OpenRouter wraps the real upstream failure under `error.metadata`.
+    // Without this, the user only sees the generic "Provider returned error".
+    private static String formatErrorMetadata(metadata) {
+        if (!metadata) return null
+        def parts = []
+        if (metadata.provider_name) parts << "provider=${metadata.provider_name}"
+        if (metadata.raw) parts << (metadata.raw as String)
+        return parts ? parts.join(', ') : null
+    }
 }
 
 class AiOpenRouterModule extends AbstractModule {