diff --git a/emacs/flan-dev.el b/emacs/flan-dev.el
index dd2bba7..fc612b6 100644
--- a/emacs/flan-dev.el
+++ b/emacs/flan-dev.el
@@ -763,6 +763,12 @@ Compared with `file-equal-p', so a symlinked or relative path still matches."
   "Face for the message shown beside a rejected form."
   :group 'flan-dev)
 
+(defun flan-dev--error-overlays (&optional buffer)
+  "The Flan error overlays in BUFFER, or in the current buffer."
+  (with-current-buffer (or buffer (current-buffer))
+    (seq-filter (lambda (o) (overlay-get o 'flan-dev-error))
+                (overlays-in (point-min) (point-max)))))
+
 (defun flan-dev-clear-errors (&optional buffer)
   "Remove Flan error overlays from BUFFER, or from the current buffer."
   (interactive)
diff --git a/emacs/test-flan-dev.el b/emacs/test-flan-dev.el
index cd5cfa9..d21a932 100644
--- a/emacs/test-flan-dev.el
+++ b/emacs/test-flan-dev.el
@@ -628,6 +628,90 @@ is written instead — the real `message' call the real command makes."
     (test-flan--check "and says nothing above the first one"
                       (null (flan-current-defun-name))))
 
+  ;; ── A rejection lasts as long as the action it was about ──────────────
+  ;;
+  ;; The overlay is feedback on the evaluation that just failed, so the next
+  ;; command in that buffer takes it down.  What is checked here is the
+  ;; mechanism and not Emacs' command loop: `execute-kbd-macro' under --batch
+  ;; runs no `pre-command-hook' at all (and does not even move point), so there
+  ;; is no way from here to make the real loop run one.  `run-hooks' is what
+  ;; the loop calls, and calling it is the closest honest thing — it proves the
+  ;; hook is installed, in the right buffer and nowhere else, and that running
+  ;; it clears the overlay and uninstalls itself.  It does not prove Emacs runs
+  ;; it, which is Emacs' own contract.
+  (let ((buf (flan-dev--buffer-visiting file)))
+    (with-current-buffer buf
+      (flan-dev-clear-errors)
+      (let ((marked (flan-dev--show-error (format "%s:2:1" file) "no such name")))
+        (test-flan--check "a rejection is marked in the buffer it came from"
+                          (and marked (flan-dev--error-overlays)))
+        (test-flan--check "and the buffer is armed to take it down again"
+                          (memq #'flan-dev--clear-errors-on-command
+                                pre-command-hook))
+        ;; Buffer-local, or every buffer in the session runs this on every
+        ;; keystroke for the sake of a buffer that had one bad evaluation.
+        (test-flan--check "and nobody else is"
+                          (not (memq #'flan-dev--clear-errors-on-command
+                                     (default-value 'pre-command-hook))))
+        (run-hooks 'pre-command-hook)
+        (test-flan--check "the next command in that buffer clears it"
+                          (null (flan-dev--error-overlays)))
+        (test-flan--check "and the hook goes with the last overlay"
+                          (not (memq #'flan-dev--clear-errors-on-command
+                                     pre-command-hook))))))
+
+  ;; ── Disassembly ───────────────────────────────────────────────────────
+  ;;
+  ;; Its own daemon, because the first one was disconnected above and a
+  ;; disassembly is a question only a live session can answer: the daemon is
+  ;; the thing that built the module and still has the .ll and the .so.
+  (let ((socket3 (concat socket "-disasm")))
+    (ignore-errors (delete-file socket3))
+    (flan-dev program socket3)
+    (test-flan--check "a daemon to disassemble against"
+                      (process-live-p flan-dev--connection))
+
+    (when (executable-find "objdump")
+      (flan-disassemble "step")
+      (with-current-buffer flan-disassembly-buffer
+        (let ((text (buffer-string)))
+          (test-flan--check "C-c C-a writes a disassembly of the name"
+                            (string-match-p "\\`; disassembly for step" text))
+          ;; The header is the half a listing cannot carry: what the answer
+          ;; claims, which for generated code is never "this is running".
+          (test-flan--check "with the daemon's own account of what it shows"
+                            (string-match-p "showing" text))
+          (test-flan--check "and instructions under it, numbered from zero"
+                            (string-match-p "^  0000  " text)))))
+
+    ;; The other half of the same question, on the same body.
+    (flan-disassemble "step" t)
+    (with-current-buffer flan-disassembly-buffer
+      (let ((text (buffer-string)))
+        (test-flan--check "C-u C-c C-a writes the IR it was built from"
+                          (and (string-match-p "\\`; LLVM IR for step" text)
+                               (string-match-p "^define .*flan\\.step" text)))
+        ;; Nothing has been evaluated into this daemon, so the body in the
+        ;; cell is still the one the process was launched with — the one case
+        ;; where what is installed *now* is knowable, and it says so.
+        (test-flan--check "and says the program is still running the host's copy"
+                          (string-match-p "host executable" text))))
+
+    ;; Refused by name rather than shown as an empty buffer.
+    (test-flan--check "a name the program does not define is refused by name"
+                      (let ((raised nil))
+                        (condition-case err (flan-disassemble "no-such-thing")
+                          (user-error (setq raised (error-message-string err))))
+                        (and raised (string-match-p "no function named" raised))))
+    (test-flan--check "and so is a global, which has no code to show"
+                      (let ((raised nil))
+                        (condition-case err (flan-disassemble "ticks")
+                          (user-error (setq raised (error-message-string err))))
+                        (and raised (string-match-p "not a function" raised))))
+
+    (flan-dev-quit)
+    (ignore-errors (delete-file socket3)))
+
   (if (zerop test-flan--failures)
       (message "flan-dev.el: all tests passed")
     (message "\n%d failure(s)" test-flan--failures)