fix(cli): don't replay transcript on the session's first benign SIGWINCH

The resize recovery treated the first SIGWINCH of a session as a width
change (no prior width to compare against), running the Ctrl+L-style
viewport clear + _OUTPUT_HISTORY replay. The 2J clear preserves
scrollback, so everything in the deque printed a second copy below the
still-visible original. After --continue/--resume the deque holds the
whole "Previous Conversation" recap plus the first live exchange, so a
benign resize signal (GNOME Terminal tab bar appearing, monitor-scale
change, focus events) duplicated the entire conversation.

Seed the width baseline when the resize hook is installed, and replay
only on an observed width change. The baseline is read from app.output
— get_app() at install time is still the DummyApplication whose
DummyOutput reports a fake 80 columns, which would turn the first real
signal back into a phantom width change. A real initial maximize or
restore still differs from the seeded width and is still recovered
(#49120 behavior preserved; verified in a pty harness both ways).

Fixes #65293

cli.py

@@ -5121,9 +5121,21 @@ class HermesCLI(CLIAgentSetupMixin, CLICommandsMixin, CLIBillingMixin):
         except Exception:
             new_width = None
         prev_width = getattr(self, "_last_resize_width", None)
-        # First resize of the session has no prior width to compare against;
-        # treat it as a change so an initial maximize/restore is covered too.
-        width_changed = new_width is not None and new_width != prev_width
+        # Replay only on an OBSERVED width change.  The first signal of a
+        # session must not count as one (#65293): GNOME Terminal and friends
+        # deliver benign SIGWINCHes (tab bar appearing, monitor-scale change,
+        # focus events), and a 2J+replay against preserved scrollback
+        # duplicates everything ``_OUTPUT_HISTORY`` holds — after a resume
+        # that is the entire "Previous Conversation" recap plus the first
+        # live exchange.  ``_install_resize_recovery`` seeds the baseline at
+        # startup, so an initial maximize/restore still differs from it and
+        # is still recovered; with no baseline (width probe failed) this
+        # signal just records one for the next comparison.
+        width_changed = (
+            new_width is not None
+            and prev_width is not None
+            and new_width != prev_width
+        )
         if width_changed:
             try:
                 self._clear_prompt_toolkit_screen(app, rebuild_scrollback=False)
@@ -5222,6 +5234,45 @@ class HermesCLI(CLIAgentSetupMixin, CLICommandsMixin, CLIBillingMixin):
             self._resize_recovery_pending = False
             self._recover_after_resize(app, original_on_resize)
 
+    def _install_resize_recovery(self, app) -> None:
+        """Route prompt_toolkit's ``_on_resize`` through the debounced
+        ghost-clearing recovery (#5474/#49120) and record the current terminal
+        width as the baseline for width-change detection.
+
+        Seeding the baseline here is what keeps the session's FIRST SIGWINCH
+        honest (#65293): ``_recover_after_resize`` replays the transcript only
+        on an observed width change, and without a startup baseline it could
+        not tell a benign signal (GNOME Terminal tab bar, monitor-scale
+        change) from a real one.  An initial maximize/restore still differs
+        from the seeded width, so it is still recovered.
+
+        The probe reads ``app.output`` directly — NOT
+        ``_get_tui_terminal_width`` — because this runs before ``app.run()``,
+        when ``get_app()`` still returns prompt_toolkit's DummyApplication
+        whose DummyOutput reports a hardcoded 80 columns; seeding that fake
+        width would make the first real signal look like a width change and
+        resurrect the duplicate-replay bug this exists to fix.
+        ``app.output`` is the same object the running app's resize handler
+        measures, so install-time and signal-time widths are comparable.
+        """
+        width = None
+        try:
+            width = app.output.get_size().columns
+        except Exception:
+            width = None
+        if not width or width <= 0:
+            try:
+                width = shutil.get_terminal_size((80, 24)).columns
+            except Exception:
+                width = None
+        self._last_resize_width = width
+        original_on_resize = app._on_resize
+
+        def _resize_clear_ghosts():
+            self._schedule_resize_recovery(app, original_on_resize)
+
+        app._on_resize = _resize_clear_ghosts
+
     def _status_bar_context_style(self, percent_used: Optional[int]) -> str:
         if percent_used is None:
             return "class:status-bar-dim"
@@ -18036,12 +18087,7 @@ class HermesCLI(CLIAgentSetupMixin, CLICommandsMixin, CLIBillingMixin):
         # don't permanently freeze the input (issue #16263). Idempotent.
         _apply_bracketed_paste_timeout_patch()
 
-        _original_on_resize = app._on_resize
-
-        def _resize_clear_ghosts():
-            self._schedule_resize_recovery(app, _original_on_resize)
-
-        app._on_resize = _resize_clear_ghosts
+        self._install_resize_recovery(app)
 
         def spinner_loop():
             while not self._should_exit: