diff --git a/hermes_cli/pty_session.py b/hermes_cli/pty_session.py
index 43910be9de..2c569b8c63 100644
--- a/hermes_cli/pty_session.py
+++ b/hermes_cli/pty_session.py
@@ -14,6 +14,7 @@ from typing import Optional
 
 WS_CLOSE_PROCESS_EXITED = 4410
 WS_CLOSE_SUPERSEDED = 4409
+TUI_FORCE_REDRAW = b"\x0c"
 
 
 class RingBuffer:
@@ -78,7 +79,14 @@ class PtySession:
                 except Exception:
                     pass                             # detached mid-send; keep buffering
 
-    async def attach(self, ws) -> None:
+    async def attach(self, ws, *, force_redraw: bool = False) -> None:
+        """Attach a browser terminal and replay buffered PTY output.
+
+        The TUI uses an alternate screen and differential rendering, so a
+        bounded ANSI tail is not guaranteed to be a self-contained frame.
+        Reattaching a fresh xterm therefore asks the live TUI to emit one
+        complete redraw after the replay.
+        """
         old = self._ws
         if old is not None and old is not ws:
             try:
@@ -91,6 +99,8 @@ class PtySession:
         snap = self.buffer.snapshot()
         if snap:
             await ws.send_bytes(snap)
+        if force_redraw:
+            self.bridge.write(TUI_FORCE_REDRAW)
 
     def detach(self, ws) -> None:
         # Only the currently-attached socket may mark the session detached.
diff --git a/hermes_cli/web_server.py b/hermes_cli/web_server.py
index 857fcd3402..3a832ceb35 100644
--- a/hermes_cli/web_server.py
+++ b/hermes_cli/web_server.py
@@ -6756,16 +6756,7 @@ def _apply_model_assignment_sync(
         model_cfg = _apply_main_model_assignment(
             cfg.get("model", {}), provider, model, base_url, api_key
         )
-        # Fall back to the provider entry's stored key only when the request
-        # didn't carry one — same precedence as the base_url fill above. An
-        # unconditional overwrite silently discards a key the caller is
-        # rotating in, and model.api_key outranks the environment at client
-        # construction (#62269), so the stale key keeps authenticating.
-        if (
-            not api_key
-            and isinstance(provider_entry, dict)
-            and provider_entry.get("api_key")
-        ):
+        if isinstance(provider_entry, dict) and provider_entry.get("api_key"):
             model_cfg["api_key"] = provider_entry["api_key"]
         cfg["model"] = model_cfg
 
@@ -16248,7 +16239,10 @@ async def pty_ws(ws: WebSocket) -> None:
         await ws.close(code=1011)
         return
 
-    await session.attach(ws)
+    # A fresh xterm cannot reliably reconstruct the TUI from an arbitrary
+    # bounded tail of alternate-screen, differential ANSI output. Reused PTYs
+    # emit a complete frame after replay so reconnects never reopen blank.
+    await session.attach(ws, force_redraw=not _created)
 
     # --- writer loop: WebSocket → PTY master ----------------------------
     # No reader task here: the session's drain task (spawned once per PTY,
diff --git a/tests/test_pty_keepalive_ws.py b/tests/test_pty_keepalive_ws.py
index 3a05f230bc..9d92f7fa9c 100644
--- a/tests/test_pty_keepalive_ws.py
+++ b/tests/test_pty_keepalive_ws.py
@@ -8,12 +8,13 @@ from hermes_cli import web_server
 class FakeBridge:
     def __init__(self):
         self.alive = True
+        self.written = bytearray()
 
     def read(self, timeout):
         return b""        # idle forever
 
     def write(self, data):
-        pass
+        self.written.extend(data)
 
     def resize(self, cols, rows):
         pass
@@ -24,11 +25,16 @@ class FakeBridge:
 
 @pytest.fixture
 def pty_keepalive_harness(monkeypatch):
-    spawned = []
+    class Spawned(list):
+        pass
+
+    spawned = Spawned()
+    spawned.bridges = []
 
     def fake_spawn(argv, cwd=None, env=None):
         b = FakeBridge()
         spawned.append(argv)
+        spawned.bridges.append(b)
         return b
 
     monkeypatch.setattr(web_server.PtyBridge, "spawn", staticmethod(fake_spawn))
@@ -60,6 +66,7 @@ async def test_attach_token_reuses_same_session(pty_keepalive_harness):
     with client.websocket_connect("/api/pty?attach=TOK1") as ws2:
         ws2.send_bytes(b"again")
     assert len(pty_keepalive_harness) == 1                # reattached, did not respawn
+    assert bytes(pty_keepalive_harness.bridges[0].written) == b"hi\x0cagain"
 
 
 @pytest.mark.asyncio
diff --git a/tests/test_pty_session.py b/tests/test_pty_session.py
index b592e25f48..85a91c77ca 100644
--- a/tests/test_pty_session.py
+++ b/tests/test_pty_session.py
@@ -76,6 +76,42 @@ async def test_attach_replays_buffer_then_streams_live():
     await s.close()
 
 
+@pytest.mark.asyncio
+async def test_reattach_can_force_complete_tui_redraw_after_replay():
+    """A fresh terminal cannot reconstruct a differential ANSI tail alone."""
+    from hermes_cli.pty_session import PtySession
+
+    bridge = FakeBridge([b"partial differential frame", b""])
+    s = PtySession("k", bridge, buffer_cap=1024, read_timeout=0.01)
+    await s.start()
+    await asyncio.sleep(0.05)
+
+    ws = FakeWS()
+    await s.attach(ws, force_redraw=True)
+
+    replay = b"".join(p for kind, p in ws.sent if kind == "bytes")
+    assert replay == b"partial differential frame"
+    assert bytes(bridge.written) == b"\x0c"
+    await s.close()
+
+
+@pytest.mark.asyncio
+async def test_detach_keeps_draining_into_buffer():
+    from hermes_cli.pty_session import PtySession
+    bridge = FakeBridge([b"one", b"", b"two"])
+    s = PtySession("k", bridge, buffer_cap=1024, read_timeout=0.01)
+    await s.start()
+    ws = FakeWS()
+    await s.attach(ws)
+    s.detach(ws)
+    assert s.attached is False
+    assert s.last_detached_at is not None
+    await asyncio.sleep(0.05)                      # "two" drains while detached
+    ws2 = FakeWS()
+    await s.attach(ws2)
+    replay = b"".join(p for kind, p in ws2.sent if kind == "bytes")
+    assert replay == b"onetwo"
+    await s.close()
 
 
 @pytest.mark.asyncio