diff --git a/CHANGELOG.md b/CHANGELOG.md
index bf6352068..d846b3799 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Build fallback variants from `/v1/models` advertised reasoning efforts (OpenRouter, Synthetic) when no built-in or user variants exist.
+
 ## 0.157.3
 
 - Add built-in effort variants for Claude models on `openai-chat` providers like OpenRouter, using the `verbosity` param which maps to Anthropic's `output_config.effort`.
diff --git a/docs/config/variants.md b/docs/config/variants.md
index 12ef53c71..f49f2fbde 100644
--- a/docs/config/variants.md
+++ b/docs/config/variants.md
@@ -98,6 +98,12 @@ ECA ships with built-in variants for some known models via the `variantsByModel`
     | `high`     | `{"reasoning_effort": "high"}` |
     | `max`      | `{"reasoning_effort": "max"}}` |
 
+## Discovered Variants
+
+Some providers (GitHub Copilot, OpenAI OAuth, and gateways like OpenRouter or Synthetic) tell ECA which reasoning effort levels a model supports, and ECA builds the variants for you. Nothing to configure: just pick an effort from the model's variant list.
+
+Discovered variants are only used when nothing else defines variants for the model. Your custom variants always win.
+
 ## Custom Variants
 
 You can define your own variants per model under `providers.<provider>.models.<model>.variants`. Custom variants are merged with built-in ones — if names clash, your definition wins.
diff --git a/integration-test/integration/chat/commands_test.clj b/integration-test/integration/chat/commands_test.clj
index 0ede5dcfd..abd6a6dbe 100644
--- a/integration-test/integration/chat/commands_test.clj
+++ b/integration-test/integration/chat/commands_test.clj
@@ -35,6 +35,7 @@
                        {:name "fork" :arguments []}
                        {:name "btw" :arguments [{:name "prompt" :required true}]}
                        {:name "resume" :arguments [{:name "chat-id"}]}
+                       {:name "delete-chat" :arguments [{:name "chat-id"}]}
                        {:name "export" :arguments [{:name "filepath"}]}
                        {:name "import" :arguments [{:name "filepath"}]}
                        {:name "remote" :arguments []}
@@ -67,6 +68,7 @@
                        {:name "costs" :arguments []}
                        {:name "context" :arguments []}
                        {:name "compact" :arguments [{:name "additional-input"}]}
+                       {:name "delete-chat" :arguments [{:name "chat-id"}]}
                        {:name "remote" :arguments []}
                        {:name "config" :arguments []}
                        {:name "subagents" :arguments []}
@@ -114,6 +116,13 @@
     (is (match? {:type "mcp"
                  :name "mcpServerSample"}
                 (eca/client-awaits-server-notification :tool/serverUpdated))))
+  (testing "Mcp prompts fetched"
+    ;; Prompts are listed after the server reports running, in a second
+    ;; notification. Await it before querying commands.
+    (is (match? {:type "mcp"
+                 :name "mcpServerSample"
+                 :prompts [{:name "my-prompt" :arguments [{:name "some-arg-1"}]}]}
+                (eca/client-awaits-server-notification :tool/serverUpdated))))
 
   (testing "MCP prompts available when querying commands"
     (let [resp (eca/request! (fixture/chat-query-commands-request
diff --git a/src/eca/config.clj b/src/eca/config.clj
index 7c57e7d83..f22b34ee1 100644
--- a/src/eca/config.clj
+++ b/src/eca/config.clj
@@ -319,9 +319,10 @@
       false)))
 
 (defn effective-model-variants
-  "Returns effective variants for a model. Built-in regex variants are the
-   fallback, discovered provider variants override them, and user variants have
-   final priority. A variant set to {} is removed from the result."
+  "Returns effective variants for a model. Discovered provider variants
+   override built-in regex variants, effort variants parsed from the provider
+   /models response are the last fallback, and user variants have final
+   priority. A variant set to {} is removed from the result."
   ([config provider model-name user-variants]
    (effective-model-variants config provider model-name nil user-variants))
   ([config provider model-name model-capabilities user-variants]
@@ -338,7 +339,9 @@
                                       (api-match? provider-api api))
                              variants))
                          (:variantsByModel config)))
-         merged (merge (or (not-empty (:variants model-capabilities)) builtin)
+         merged (merge (or (not-empty (:variants model-capabilities))
+                           builtin
+                           (not-empty (:effort-variants model-capabilities)))
                        user-variants)]
      (when (seq merged)
        (let [filtered (into {} (remove (fn [[_ v]] (= {} v))) merged)]
diff --git a/src/eca/models.clj b/src/eca/models.clj
index f3301158a..212bc71fc 100644
--- a/src/eca/models.clj
+++ b/src/eca/models.clj
@@ -427,6 +427,26 @@
                       :discovered-reason? (when reason? true)
                       :discovered-variants (not-empty variants))])))
 
+(def ^:private effort-list-paths
+  [[:reasoning :supported_efforts]     ; OpenRouter
+   [:reasoning_parameters :efforts]])  ; Synthetic
+
+(defn ^:private native-reasoning-effort-variants
+  "Builds openai-chat variants from a /models entry's advertised reasoning
+   efforts. Nil for other APIs or when no efforts are advertised."
+  [api-type entry]
+  (when (= "openai-chat" api-type)
+    (let [advertised (some (fn [path]
+                             (let [efforts (get-in entry path)]
+                               (when (sequential? efforts) efforts)))
+                           effort-list-paths)]
+      (not-empty
+       (into {}
+             (keep (fn [effort]
+                     (when (string? effort)
+                       [effort {:reasoning_effort effort}]))
+             advertised))))))
+
 (defn ^:private parse-native-model-entry
   "Parses a generic /models entry. OpenRouter-shaped entries expose
    `context_length` and `top_provider.max_completion_tokens`; llama.cpp /
@@ -435,17 +455,19 @@
    provider-reported data wins over models.dev catalogs. Entries without that
    metadata (e.g. plain OpenAI/Anthropic) keep an empty config, preserving the
    previous id-only behavior."
-  [{:keys [id context_length top_provider] entry-meta :meta}]
+  [{:keys [id context_length top_provider] entry-meta :meta :as entry} api-type]
   (when (and (string? id) (not (string/blank? id)))
     (let [context (or (pos-num context_length)
                       (pos-num (:n_ctx entry-meta))
                       (pos-num (:n_ctx_train entry-meta)))
-          output (sane-output-limit context (pos-num (:max_completion_tokens top_provider)))]
+          output (sane-output-limit context (pos-num (:max_completion_tokens top_provider)))
+          effort-variants (native-reasoning-effort-variants api-type entry)]
       [id (assoc-some {}
                       :discovered-limit (not-empty
                                          (assoc-some {}
                                                      :context context
-                                                     :output output)))])))
+                                                     :output output))
+                      :discovered-effort-variants effort-variants)])))
 
 (defn ^:private fetch-provider-native-models
   "Fetches models from provider's native /models endpoint.
@@ -481,7 +503,7 @@
                   (not-empty
                    (if (= "github-copilot" provider)
                      (into {} (keep parse-copilot-model-entry) models-data)
-                     (into {} (keep parse-native-model-entry) models-data))))))))
+                     (into {} (keep #(parse-native-model-entry % api-type) models-data)))))))))
         (catch Exception e
           (logger/warn logger-tag
                        (format "Provider '%s': Failed to fetch models from %s: %s"
@@ -577,8 +599,9 @@
 (defn ^:private config-overrides->capabilities
   "Translate per-model config and discovered provider metadata into internal
    capability keys. User limits, costs, and image support override catalog
-   values; provider discovery contributes API routing, reasoning variants, and
-   token limits (user config > provider-discovered > models.dev catalog)."
+   values; provider discovery contributes API routing, reasoning variants,
+   effort variants, and token limits (user config > provider-discovered >
+   models.dev catalog)."
   [model-config]
   (let [limit (:limit model-config)
         cost (:cost model-config)
@@ -592,6 +615,7 @@
                 :reason? (:discovered-reason? model-config)
                 :api (:discovered-api model-config)
                 :variants (:discovered-variants model-config)
+                :effort-variants (:discovered-effort-variants model-config)
                 ;; Opaque provider-specific model metadata, interpreted only by
                 ;; the provider adapter that discovered it.
                 :provider-data (not-empty (:discovered-provider-data model-config))
diff --git a/test/eca/config_test.clj b/test/eca/config_test.clj
index c9d28b129..465b2669e 100644
--- a/test/eca/config_test.clj
+++ b/test/eca/config_test.clj
@@ -699,6 +699,19 @@
                :variants {"low" {:source "endpoint"}}}
               {"high" {:source "user"}}))))
 
+    (testing "Effort variants from /models are the last fallback"
+      (let [effort-variants {"low" {:reasoning_effort "low"}
+                             "high" {:reasoning_effort "high"}}
+            caps {:api :openai-chat :effort-variants effort-variants}]
+        (is (= effort-variants
+               (config/effective-model-variants {} "synthetic" "qwen3" caps nil)))
+        (is (= anthropic-variants
+               (config/effective-model-variants config "my-proxy" "claude-opus-4-6"
+                                                (assoc caps :api :anthropic) nil)))
+        (is (= {"low" {:reasoning_effort "low"}}
+               (config/effective-model-variants {} "synthetic" "qwen3" caps
+                                                {"high" {}})))))
+
     (testing "User variant set to {} removes a discovered variant"
       (is (= {"low" {:source "endpoint"}}
              (config/effective-model-variants
diff --git a/test/eca/llm_api_test.clj b/test/eca/llm_api_test.clj
index 859b20b35..b1b8d407d 100644
--- a/test/eca/llm_api_test.clj
+++ b/test/eca/llm_api_test.clj
@@ -1125,7 +1125,10 @@
           final-error* (atom nil)
           error {:status 503
                  :body "{\"error\":{\"message\":\"auth_unavailable: no auth available (providers=codex, model=gpt-5.6-sol)\",\"type\":\"server_error\",\"code\":\"internal_server_error\"}}"
-                 :message "OpenAI response status: 503 body: auth_unavailable"}]
+                 :message "OpenAI response status: 503 body: auth_unavailable"}
+          delivered-error (assoc error
+                                 :message "Anthropic server_error: auth_unavailable: no auth available (providers=codex, model=gpt-5.6-sol)"
+                                 :code "server_error")]
       (with-redefs [eca.llm-api/prompt! (fn [_]
                                           (swap! attempt* inc)
                                           {:error error})
@@ -1154,7 +1157,7 @@
               :backoff-multiplier 3.0
               :max-delay-ms 250}
              (:policy (first @retry-events*))))
-      (is (= error @final-error*)))))
+      (is (= delivered-error @final-error*)))))
 
 (deftest sync-retry-cancelled-test
   (testing "stops retrying when cancelled"
diff --git a/test/eca/models_test.clj b/test/eca/models_test.clj
index 9497c92fb..e4ebc5061 100644
--- a/test/eca/models_test.clj
+++ b/test/eca/models_test.clj
@@ -285,6 +285,66 @@
              :api-key "k"
              :api-type "openai-chat"}))))))
 
+(deftest fetch-provider-native-models-effort-variants-test
+  (testing "OpenRouter and Synthetic shaped efforts become discovered effort variants"
+    (with-redefs [http/get (fn [_url _opts]
+                             {:status 200
+                              :body {:data
+                                     [{:id "tencent/hy4-preview"
+                                       :reasoning {:supported_efforts ["high" "low" 1]}}
+                                      {:id "syn:small:text"
+                                       :reasoning_parameters {:efforts ["none" "low"]}}
+                                      {:id "bad-efforts"
+                                       :reasoning {:supported_efforts 1}}
+                                      {:id "plain-model"}]}})]
+      (is (match?
+           (m/equals
+            {"tencent/hy4-preview"
+             (m/equals {:discovered-effort-variants
+                        {"high" {:reasoning_effort "high"}
+                         "low" {:reasoning_effort "low"}}})
+             "syn:small:text"
+             (m/equals {:discovered-effort-variants
+                        {"none" {:reasoning_effort "none"}
+                         "low" {:reasoning_effort "low"}}})
+             "bad-efforts" (m/equals {})
+             "plain-model" (m/equals {})})
+           (#'models/fetch-provider-native-models
+            {:provider "openrouter"
+             :api-url "https://openrouter.ai/api/v1"
+             :auth-type nil
+             :api-key "k"
+             :api-type "openai-chat"})))))
+
+  (testing "other APIs build no effort variants from the same metadata"
+    (with-redefs [http/get (fn [_url _opts]
+                             {:status 200
+                              :body {:data [{:id "claude-x"
+                                             :reasoning {:supported_efforts ["low" "high"]}}]}})]
+      (is (match?
+           {"claude-x" {}}
+           (#'models/fetch-provider-native-models
+            {:provider "my-proxy"
+             :api-url "https://api.anthropic.com"
+             :auth-type nil
+             :api-key "k"
+             :api-type "anthropic"}))))))
+
+(deftest synthetic-provider-effort-variants-build-model-capabilities-test
+  (testing "Effort variants from a synthetic /v1/models flow into model capabilities"
+    (let [config {:providers {"synthetic" {:api "openai-chat"
+                                           :url "https://api.synthetic.new/v1"
+                                           :key "sk-test"
+                                           :models {"hf:Qwen/Qwen3-235B" {}}}}}]
+      (with-redefs [http/get (fn [_url _opts]
+                               {:status 200
+                                :body {:data [{:id "hf:Qwen/Qwen3-235B"
+                                               :reasoning_parameters {:efforts ["high" "low"]}}]}})]
+        (is (= {"high" {:reasoning_effort "high"}
+                "low" {:reasoning_effort "low"}}
+               (get-in (build-supported-models config {} {})
+                       ["synthetic/hf:Qwen/Qwen3-235B" :effort-variants])))))))
+
 (deftest fetch-provider-native-llamacpp-models-limits-test
   (testing "llama.cpp/llama-swap-shaped entries keep meta n_ctx (falling back to n_ctx_train) as discovered context limit"
     (with-redefs [http/get (fn [_url _opts]