Show subagent model variant in spawn_agent details table

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Show the model variant of a running subagent in the `spawn_agent` tool call details table when the server sends one.
 - Bugfix: kill commands not covered by the deletion guards (`backward-kill-sentence`, `backward-kill-sexp`, `kill-line`, `kill-region`, etc.) could cross the prompt/context markup and corrupt the chat prompt area, making RET fail with `args-out-of-range` (#305). Kills are now clamped to the prompt field (and blocked above it), the transient-area refresh skips instead of signaling on a corrupted block, and `eca-chat-clear-prompt` (`C-c C-d`) rebuilds the prompt markup when it is broken.
 
 - Perf: cache the pending tool call approval status instead of rescanning the whole chat buffer on every mode-line/tab-line/header-line redisplay, which made Emacs sluggish on long chats (#307).

eca-chat.el

@@ -3960,6 +3960,7 @@ Append STATUS symbol.  Optional PARENT-ID for nested rendering."
   (-let* ((agent-name (plist-get args :agent))
           (task (plist-get args :task))
           (model (plist-get details :model))
+          (variant (plist-get details :variant))
           (step (plist-get details :step))
           (max-steps (plist-get details :maxSteps))
           (usage-str (eca-chat--subagent-usage-str id))
@@ -4013,6 +4014,7 @@ Append STATUS symbol.  Optional PARENT-ID for nested rendering."
        (eca-chat--content-table
         `(("Agent" . ,agent-name)
           ("Model" . ,model)
+          ,@(when variant `(("Variant" . ,variant)))
           ,@(when task `(("Task" . ,(concat task "\n\n"))))
           ,@(when output-text `(("Output" . ,(concat "\n" output-text))))))
        nil

test/eca-chat-test.el

@@ -233,6 +233,33 @@ When MANUAL is non-nil the tool call requires manual approval."
             (expect (overlay-get (eca-chat--get-expandable-content "parent-1")
                                  'eca-chat--tool-call-status)
                     :to-equal eca-chat-mcp-tool-call-loading-symbol))
+        (kill-buffer buf))))
+
+  (it "shows the subagent variant row when details carry one"
+    (let ((buf (eca-chat-test--make-render-buffer)))
+      (unwind-protect
+          (eca-chat--with-current-buffer buf
+            (eca-chat--tool-call-subagent-details
+             "sub-1" (list :agent "test-agent" :task "task")
+             "Calling subagent" nil nil
+             eca-chat-mcp-tool-call-loading-symbol nil
+             (list :type "subagent" :model "test-model" :variant "high"))
+            (eca-chat--expandable-content-toggle "sub-1" t nil)
+            (expect (buffer-string) :to-match "Variant")
+            (expect (buffer-string) :to-match "high"))
+        (kill-buffer buf))))
+
+  (it "omits the subagent variant row when details have none"
+    (let ((buf (eca-chat-test--make-render-buffer)))
+      (unwind-protect
+          (eca-chat--with-current-buffer buf
+            (eca-chat--tool-call-subagent-details
+             "sub-2" (list :agent "test-agent" :task "task")
+             "Calling subagent" nil nil
+             eca-chat-mcp-tool-call-loading-symbol nil
+             (list :type "subagent" :model "test-model"))
+            (eca-chat--expandable-content-toggle "sub-2" t nil)
+            (expect (buffer-string) :not :to-match "Variant"))
         (kill-buffer buf)))))
 
 (describe "eca-chat--apply-markdown-markup-visibility"