diff --git a/ai-code-prompt-mode.el b/ai-code-prompt-mode.el
index d143be8e..9b3bee82 100644
--- a/ai-code-prompt-mode.el
+++ b/ai-code-prompt-mode.el
@@ -22,6 +22,11 @@
 (defvar ai-code-discussion-auto-follow-up-enabled)
 (defvar ai-code-discussion-auto-follow-up-suffix)
 (defvar ai-code-use-prompt-suffix)
+(defvar ai-code-backends-infra--session-terminal-backend nil
+  "Buffer-local terminal backend symbol for an AI session buffer, or nil.
+This is set by `ai-code-backends-infra.el' for terminal-managed sessions
+such as `vterm' and `eat'.  A nil value means the buffer is not managed by
+the terminal backend infrastructure.")
 
 (declare-function yas-load-directory "yasnippet" (dir))
 (declare-function yas-minor-mode "yasnippet")
@@ -35,6 +40,11 @@
 (declare-function ai-code--choose-symbol-from-file "ai-code-input" (file))
 (declare-function ai-code-read-string "ai-code-input" (prompt &optional initial-input candidate-list))
 (declare-function ai-code-current-backend-label "ai-code-backends" ())
+(declare-function ai-code-backends-infra--session-buffer-p "ai-code-backends-infra" (buffer))
+(declare-function ai-code-backends-infra--session-buffer-matches-directory-p "ai-code-backends-infra" (buffer directory))
+(declare-function ai-code-backends-infra--terminal-send-string "ai-code-backends-infra" (string))
+(declare-function ai-code-backends-infra--terminal-send-return "ai-code-backends-infra" ())
+(declare-function ai-code-backends-infra--display-buffer-in-side-window "ai-code-backends-infra" (buffer))
 
 (defcustom ai-code-prompt-preprocess-filepaths t
   "When non-nil, preprocess the prompt to replace file paths.
@@ -176,10 +186,70 @@ that should be recorded in the prompt history file."
   (ai-code--insert-backend-label-drawer)
   (ai-code--format-and-insert-prompt stored-prompt-text))
 
+(defun ai-code--find-visible-session-buffer ()
+  "Return a visible terminal-managed AI session buffer in the current frame."
+  (cl-some
+   (lambda (win)
+     (let ((buf (window-buffer win)))
+       (when (and (buffer-live-p buf)
+                  (ai-code-backends-infra--session-buffer-p buf)
+                  (buffer-local-value
+                   'ai-code-backends-infra--session-terminal-backend buf))
+         buf)))
+   (window-list nil 'no-minibuffer)))
+
+(defun ai-code--find-project-session-buffers ()
+  "Return terminal-managed AI session buffers associated with the current project."
+  (when-let ((git-root (ai-code--git-root)))
+    (cl-remove-if-not
+     (lambda (buf)
+       (and (ai-code-backends-infra--session-buffer-p buf)
+            (buffer-local-value
+             'ai-code-backends-infra--session-terminal-backend buf)
+            (ai-code-backends-infra--session-buffer-matches-directory-p buf git-root)))
+     (buffer-list))))
+
+(defun ai-code--prompt-choose-target-session ()
+  "Choose AI session buffer to send prompt to.
+Return session buffer for direct routing, or nil to use default backend dispatch."
+  (when-let ((visible-session (ai-code--find-visible-session-buffer)))
+    (let* ((project-sessions (ai-code--find-project-session-buffers))
+           (visible-is-project-session (memq visible-session project-sessions))
+           (competing-sessions
+            (cl-remove visible-session project-sessions)))
+      (cond
+       (visible-is-project-session nil)
+       ((null competing-sessions)
+        visible-session)
+       (t
+        (let* ((choice-alist (mapcar (lambda (buf)
+                                       (cons (buffer-name buf) buf))
+                                     (cons visible-session competing-sessions)))
+               (selection (completing-read
+                           "Multiple AI sessions available.  Send to: "
+                           (mapcar #'car choice-alist)
+                           nil t nil nil (buffer-name visible-session))))
+          (cdr (assoc selection choice-alist))))))))
+
+(defun ai-code--send-prompt-to-session-buffer (prompt buffer)
+  "Send PROMPT directly to session BUFFER and display it."
+  (with-current-buffer buffer
+    (ai-code-backends-infra--terminal-send-string prompt)
+    (sit-for 0.5)
+    (ai-code-backends-infra--terminal-send-return))
+  (if-let ((window (get-buffer-window buffer)))
+      (select-window window)
+    (ai-code-backends-infra--display-buffer-in-side-window buffer)))
+
 (defun ai-code--send-prompt (full-prompt)
-  "Send FULL-PROMPT to AI."
-  (ai-code-cli-send-command full-prompt)
-  (ai-code-cli-switch-to-buffer))
+  "Send FULL-PROMPT to AI.
+When a visible AI session buffer is detected in the current frame,
+send the prompt directly to it instead of going through the default
+backend dispatch."
+  (if-let ((target (ai-code--prompt-choose-target-session)))
+      (ai-code--send-prompt-to-session-buffer full-prompt target)
+    (ai-code-cli-send-command full-prompt)
+    (ai-code-cli-switch-to-buffer)))
 
 (defun ai-code--write-prompt-to-file-and-send (prompt-text)
   "Write PROMPT-TEXT to the AI prompt file."
diff --git a/test/test_ai-code-prompt-mode.el b/test/test_ai-code-prompt-mode.el
index d320d79e..dd53f170 100644
--- a/test/test_ai-code-prompt-mode.el
+++ b/test/test_ai-code-prompt-mode.el
@@ -1474,5 +1474,169 @@ and ensures everything is cleaned up afterward."
         (should (string-match-p (regexp-quote ":AGENT: gemini") content))
         (should (string-match-p (regexp-quote ":END:") content))))))
 
+;;; Tests for visible session routing in ai-code--send-prompt
+
+(ert-deftest ai-code-test-find-visible-session-buffer-returns-session ()
+  "Find a session buffer in visible windows."
+  (let ((session-buf (get-buffer-create "*claude[test-project]*")))
+    (unwind-protect
+        (with-current-buffer session-buf
+          (setq-local ai-code-backends-infra--session-terminal-backend 'vterm)
+          (cl-letf (((symbol-function 'window-list)
+                     (lambda (&optional _frame _no-minibuf)
+                       '(win1 win2)))
+                    ((symbol-function 'window-buffer)
+                     (lambda (win)
+                       (if (eq win 'win1) (get-buffer "*scratch*") session-buf))))
+            (should (eq (ai-code--find-visible-session-buffer) session-buf))))
+      (kill-buffer session-buf))))
+
+(ert-deftest ai-code-test-find-visible-session-buffer-nil-when-no-sessions ()
+  "Return nil when no session buffers are visible."
+  (cl-letf (((symbol-function 'window-list)
+             (lambda (&optional _frame _no-minibuf) '(win1)))
+            ((symbol-function 'window-buffer)
+             (lambda (_win) (get-buffer "*scratch*"))))
+    (should-not (ai-code--find-visible-session-buffer))))
+
+(ert-deftest ai-code-test-find-visible-session-buffer-ignores-non-terminal-sessions ()
+  "Ignore visible session-like buffers that are not terminal managed."
+  (let ((session-buf (get-buffer-create "*claude[test-project]*")))
+    (unwind-protect
+        (cl-letf (((symbol-function 'window-list)
+                   (lambda (&optional _frame _no-minibuf) '(win1)))
+                  ((symbol-function 'window-buffer)
+                   (lambda (_win) session-buf)))
+          (should-not (ai-code--find-visible-session-buffer)))
+      (kill-buffer session-buf))))
+
+(ert-deftest ai-code-test-find-project-session-buffers-finds-matching ()
+  "Find session buffers matching the current project directory."
+  (ai-code-with-test-repo
+   (let ((session-buf (get-buffer-create "*claude[test-repo]*")))
+     (unwind-protect
+          (with-current-buffer session-buf
+            (setq-local ai-code-backends-infra--session-terminal-backend 'vterm)
+            (cl-letf (((symbol-function 'ai-code-backends-infra--session-buffer-matches-directory-p)
+                      (lambda (_buf _dir) (eq _buf session-buf))))
+              (should (memq session-buf (ai-code--find-project-session-buffers)))))
+        (kill-buffer session-buf)))))
+
+(ert-deftest ai-code-test-find-project-session-buffers-excludes-other-projects ()
+  "Exclude session buffers for other projects."
+  (ai-code-with-test-repo
+   (let ((other-buf (get-buffer-create "*claude[other-project]*")))
+     (unwind-protect
+          (with-current-buffer other-buf
+            (setq-local ai-code-backends-infra--session-terminal-backend 'vterm)
+            (cl-letf (((symbol-function 'ai-code-backends-infra--session-buffer-matches-directory-p)
+                      (lambda (_buf _dir) nil)))
+              (should-not (memq other-buf (ai-code--find-project-session-buffers)))))
+        (kill-buffer other-buf)))))
+
+(ert-deftest ai-code-test-find-project-session-buffers-excludes-non-terminal-sessions ()
+  "Exclude project sessions that are not terminal managed."
+  (ai-code-with-test-repo
+   (let ((session-buf (get-buffer-create "*claude[test-repo]*")))
+     (unwind-protect
+         (cl-letf (((symbol-function 'ai-code-backends-infra--session-buffer-matches-directory-p)
+                    (lambda (_buf _dir) t)))
+           (should-not (memq session-buf (ai-code--find-project-session-buffers))))
+       (kill-buffer session-buf)))))
+
+(ert-deftest ai-code-test-prompt-choose-target-session-nil-when-no-visible ()
+  "Return nil when no visible session buffers."
+  (cl-letf (((symbol-function 'ai-code--find-visible-session-buffer)
+             (lambda () nil)))
+    (should-not (ai-code--prompt-choose-target-session))))
+
+(ert-deftest ai-code-test-prompt-choose-target-session-returns-visible-when-only-option ()
+  "Return nil when visible session belongs to the same project (default dispatch)."
+  (let ((session-buf (get-buffer-create "*claude[test]*")))
+    (unwind-protect
+        (cl-letf (((symbol-function 'ai-code--find-visible-session-buffer)
+                   (lambda () session-buf))
+                  ((symbol-function 'ai-code--find-project-session-buffers)
+                   (lambda () (list session-buf))))
+          (should-not (ai-code--prompt-choose-target-session)))
+      (kill-buffer session-buf))))
+
+(ert-deftest ai-code-test-prompt-choose-target-session-returns-visible-when-no-project-session ()
+  "Return visible session buffer when current project has no sessions."
+  (let ((visible-buf (get-buffer-create "*gemini[other-project]*")))
+    (unwind-protect
+        (cl-letf (((symbol-function 'ai-code--find-visible-session-buffer)
+                   (lambda () visible-buf))
+                  ((symbol-function 'ai-code--find-project-session-buffers)
+                   (lambda () nil)))
+          (should (eq (ai-code--prompt-choose-target-session) visible-buf)))
+      (kill-buffer visible-buf))))
+
+(ert-deftest ai-code-test-prompt-choose-target-session-asks-when-sessions-differ ()
+  "Ask user to choose when visible and project sessions differ."
+  (let ((visible-buf (get-buffer-create "*gemini[other-project]*"))
+        (project-buf (get-buffer-create "*claude[my-project]*"))
+        (offered-choices nil))
+    (unwind-protect
+        (cl-letf (((symbol-function 'ai-code--find-visible-session-buffer)
+                   (lambda () visible-buf))
+                  ((symbol-function 'ai-code--find-project-session-buffers)
+                   (lambda () (list project-buf)))
+                  ((symbol-function 'completing-read)
+                   (lambda (_prompt collection &rest _args)
+                     (setq offered-choices collection)
+                     (buffer-name project-buf))))
+          (let ((result (ai-code--prompt-choose-target-session)))
+            (should (eq result project-buf))
+            (should (member (buffer-name visible-buf) offered-choices))
+            (should (member (buffer-name project-buf) offered-choices))))
+      (kill-buffer visible-buf)
+      (kill-buffer project-buf))))
+
+(ert-deftest ai-code-test-send-prompt-uses-visible-session-directly ()
+  "Send prompt directly to visible session when target is resolved."
+  (let ((session-buf (get-buffer-create "*claude[test]*"))
+        (sent-string nil)
+        (return-sent nil)
+        (displayed-buffer nil)
+        (cli-send-called nil))
+    (unwind-protect
+        (cl-letf (((symbol-function 'ai-code--prompt-choose-target-session)
+                   (lambda () session-buf))
+                  ((symbol-function 'ai-code-backends-infra--terminal-send-string)
+                   (lambda (str) (setq sent-string str)))
+                  ((symbol-function 'ai-code-backends-infra--terminal-send-return)
+                   (lambda () (setq return-sent t)))
+                  ((symbol-function 'get-buffer-window)
+                   (lambda (_buf &rest _) nil))
+                  ((symbol-function 'ai-code-backends-infra--display-buffer-in-side-window)
+                   (lambda (buf) (setq displayed-buffer buf)))
+                  ((symbol-function 'ai-code-cli-send-command)
+                   (lambda (_cmd) (setq cli-send-called t)))
+                  ((symbol-function 'ai-code-cli-switch-to-buffer)
+                   (lambda () nil))
+                  ((symbol-function 'sit-for)
+                   (lambda (_secs) nil)))
+          (ai-code--send-prompt "test prompt")
+          (should (string= sent-string "test prompt"))
+          (should return-sent)
+          (should (eq displayed-buffer session-buf))
+          (should-not cli-send-called))
+      (kill-buffer session-buf))))
+
+(ert-deftest ai-code-test-send-prompt-falls-through-when-no-visible-session ()
+  "Use default path when no visible session is chosen."
+  (let ((cli-send-called nil)
+        (switch-called nil))
+    (cl-letf (((symbol-function 'ai-code--prompt-choose-target-session)
+               (lambda () nil))
+              ((symbol-function 'ai-code-cli-send-command)
+               (lambda (cmd) (setq cli-send-called cmd)))
+              ((symbol-function 'ai-code-cli-switch-to-buffer)
+               (lambda () (setq switch-called t))))
+      (ai-code--send-prompt "test prompt")
+      (should (string= cli-send-called "test prompt"))
+      (should switch-called))))
+
 (provide 'test-ai-code-prompt-mode)
 ;;; test_ai-code-prompt-mode.el ends here