editor-code-assistant · itkonen · Jul 17, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Support `variant` in Markdown agent frontmatter.
+
 ## 0.147.3
 
 - Fix remote server silently falling back to HTTP when the TLS private key is in SEC1 EC format; validate keys before caching and log HTTP fallback. #521

diff --git a/docs/config/agents.md b/docs/config/agents.md
@@ -110,6 +110,7 @@ Subagents can be configured in config or markdown and support/require these fiel
 - `inherit` (optional): name of another agent to inherit all settings from. The subagent's own fields are merged on top.
 - `spawnableBy` (optional): one primary agent ID or a collection of primary agent IDs allowed to discover and spawn this subagent. When omitted or empty, the subagent remains available to every primary agent.
 - `model` (optional): which full model to use for this subagent, using primary agent model if not specified.
+- `variant` (optional): default model variant; ignored when unavailable for the selected model. See [Variants](variants.md#agent-default-variant).
 - `tools` (optional): same as ECA tool approval logic to control what tools are allowed/askable/denied.
 - `disabledTools` (optional): tools to hide from this agent entirely. Same matching as the global [`disabledTools`](tools.md#disabled-tools): a builtin tool name or regex (no `eca__` prefix needed), an exact MCP server name (all its tools), or a regex against the tool full name `server__tool`.
 - `maxSteps` (optional): set a max limit of turns/steps that his subagent must finish and return an answer.
@@ -186,6 +187,7 @@ The `/config` command intentionally remains an administrative, raw resolved-conf
     mode: subagent
     description: You sleep one second when asked
     model: ${env:MY_MODEL:anthropic/sonnet-4.5}
+    variant: high
     tools:
       byDefault: ask
       deny: 
@@ -241,6 +243,7 @@ The `/config` command intentionally remains an administrative, raw resolved-conf
           "description": "You sleep one second when asked",
           "systemPrompt": "You should run sleep 1 and return \"I slept 1 second\"",
           "defaultModel": "anthropic/sonnet-4.5",
+          "variant": "high",
           "toolCall": {...},
           "maxSteps": 25 // Optional: to limit turns in subagent
         }

diff --git a/docs/config/variants.md b/docs/config/variants.md
@@ -137,17 +137,32 @@ To disable a specific built-in variant, set it to `{}`:
 
 ## Agent Default Variant
 
-You can set a default variant for an agent so it starts with that variant pre-selected:
+Set a default variant for an agent:
 
-```javascript title="~/.config/eca/config.json"
-{
-  "agent": {
-    "code": {
-      "variant": "medium"
+=== "JSON"
+
+    ```javascript title="~/.config/eca/config.json"
+    {
+      "agent": {
+        "code": {
+          "variant": "medium"
+        }
+      }
     }
-  }
-}
-```
+    ```
+
+=== "Markdown"
+
+    ```markdown title="~/.config/eca/agents/reviewer.md"
+    ---
+    mode: subagent
+    description: Review code changes
+    model: openai/gpt-5.4
+    variant: high
+    ---
+
+    Review the changes for correctness and regressions.
+    ```
 
-If the configured variant doesn't exist for the current model, it will be ignored.
+Unavailable variants are ignored. An explicit chat or `spawn_agent` variant overrides the agent default. See [Agents](agents.md) for the complete agent specification.
 
diff --git a/src/eca/features/agents.clj b/src/eca/features/agents.clj
@@ -67,6 +67,11 @@
       (when-not (string/blank? normalized)
         normalized))))
 
+(defn ^:private normalize-agent-variant
+  [variant]
+  (when (string? variant)
+    (not-empty (string/trim variant))))
+
 (defn ^:private normalize-spawnable-by
   [spawnable-by]
   (cond
@@ -105,8 +110,9 @@
             nil)))
 
 (defn ^:private md->agent-config
-  [{:keys [description mode model steps tools body inherit spawnableBy disabledTools]}]
-  (let [tools-map (normalize-tools tools)
+  [{:keys [description mode model variant steps tools body inherit spawnableBy disabledTools]}]
+  (let [agent-variant (normalize-agent-variant variant)
+        tools-map (normalize-tools tools)
         spawnable-by (normalize-spawnable-by spawnableBy)
         disabled-tools (normalize-disabled-tools disabledTools)]
     (cond-> {}
@@ -118,6 +124,7 @@
                           (mapv str mode)
                           (str mode)))
       model (assoc :defaultModel (str model))
+      agent-variant (assoc :variant agent-variant)
       steps (assoc :maxSteps (long steps))
       (seq body) (assoc :systemPrompt body)
       tools-map (assoc :toolCall

diff --git a/test/eca/config_test.clj b/test/eca/config_test.clj
@@ -243,6 +243,16 @@
       (is (= ["duel"] (get-in resolved ["inherited-worker" :spawnableBy])))
       (is (= ["other"] (get-in resolved ["overridden-worker" :spawnableBy])))))
 
+  (testing "variant follows normal inheritance and child override behavior"
+    (let [agents {"worker" {:mode "subagent"
+                             :variant "medium"}
+                  "inherited-worker" {:inherit "worker"}
+                  "overridden-worker" {:inherit "worker"
+                                       :variant "high"}}
+          resolved (#'config/resolve-agent-inheritance agents)]
+      (is (= "medium" (get-in resolved ["inherited-worker" :variant])))
+      (is (= "high" (get-in resolved ["overridden-worker" :variant])))))
+
   (testing "child values override parent values"
     (let [agents {"code" {:mode "primary"
                           :disabledTools ["preview_file_change"]

diff --git a/test/eca/features/agents_test.clj b/test/eca/features/agents_test.clj
@@ -62,6 +62,7 @@
                   "description: You sleep one second when asked\n"
                   "mode: subagent\n"
                   "model: my-org-anthropic/sonnet-4.5\n"
+                  "variant: High\n"
                   "steps: 5\n"
                   "tools:\n"
                   "  byDefault: ask\n"
@@ -77,13 +78,22 @@
       (is (match? {:description "You sleep one second when asked"
                    :mode "subagent"
                    :defaultModel "my-org-anthropic/sonnet-4.5"
+                   :variant "High"
                    :maxSteps 5
                    :systemPrompt "You should run sleep 1 and return \"I sleeped 1 second\""
                    :toolCall {:approval {:byDefault "ask"
                                          :allow {"eca__shell_command" {}}
                                          :deny {"foo" {}}}}}
                   config))))
 
+  (testing "variant is trimmed without changing case"
+    (is (= "XHigh"
+           (:variant (#'agents/md->agent-config {:variant "  XHigh  "})))))
+
+  (testing "blank or malformed variant is ignored"
+    (doseq [variant [nil "" "  " 42 [] {}]]
+      (is (nil? (:variant (#'agents/md->agent-config {:variant variant}))))))
+
   (testing "tool entries with regex patterns"
     (let [parsed {:tools {"byDefault" "ask"
                           "allow" ["eca__shell_command(npm run .*)"
@@ -259,6 +269,7 @@
                  "description: Reviews code changes\n"
                  "mode: subagent\n"
                  "model: anthropic/sonnet-4.5\n"
+                 "variant: high\n"
                  "steps: 10\n"
                  "---\n\n"
                  "You are a code reviewer."))
@@ -276,6 +287,7 @@
         (is (match? ["reviewer" {:description "Reviews code changes"
                                  :mode "subagent"
                                  :defaultModel "anthropic/sonnet-4.5"
+                                 :variant "high"
                                  :maxSteps 10
                                  :systemPrompt "You are a code reviewer."}]
                     reviewer))
@@ -318,30 +330,35 @@
             (str "---\n"
                  "description: From markdown\n"
                  "mode: subagent\n"
+                 "variant: medium\n"
                  "---\n\n"
                  "I am from markdown."))
       ;; Agent defined in JSON config should take precedence over MD agent
       (spit (fs/file local-agents-dir "json-override.md")
             (str "---\n"
                  "description: MD version\n"
                  "mode: subagent\n"
+                 "variant: low\n"
                  "---\n\n"
                  "MD prompt."))
 
       (reset! config/initialization-config*
               {:pureConfig false
                :agent {"json-override" {:mode "subagent"
                                         :description "JSON version"
+                                        :variant "high"
                                         :systemPrompt "JSON prompt."}}})
       (let [db {:workspace-folders [{:uri (shared/filename->uri (str tmp-dir))}]}
             result (#'config/all* db)]
         (testing "markdown agent is present in config"
           (is (match? {:description "From markdown"
                        :mode "subagent"
+                       :variant "medium"
                        :systemPrompt "I am from markdown."}
                       (get-in result [:agent "md-agent"]))))
         (testing "JSON config agent takes precedence over same-named MD agent"
           (is (= "JSON version" (get-in result [:agent "json-override" :description])))
+          (is (= "high" (get-in result [:agent "json-override" :variant])))
           (is (= "JSON prompt." (get-in result [:agent "json-override" :systemPrompt])))))
       (finally
         (fs/delete-tree tmp-dir)))))