diff --git a/CHANGELOG.md b/CHANGELOG.md
index 80670d28..fa800554 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@
 
 ### Fixed
 
+- **The transcript no longer scrolls up when the composer grows.** When you were pinned to the bottom of a conversation and the composer got taller — multi-line typing, `Shift+Enter`, or a multi-line / dictation paste — the transcript viewport shrank by the same amount and left you stranded a row or two above the bottom (it read as the chat "randomly scrolling up" during normal use). The transcript now re-pins to the bottom whenever the composer grows, but only when you were genuinely still pinned there — if you'd scrolled up to read history, nothing yanks you back down. (#5516, #5514, #5515)
 - **A deleted conversation no longer comes back as a read-only "ghost" after a restart.** Deleting a WebUI session removed its file but left a recoverable row in the agent's state database, so after a server restart and page reload the deleted conversation could reappear as a read-only "Agent" session still showing its old transcript. Deleted WebUI sessions are now recorded in a durable tombstone that the sidebar projection, startup backup-recovery, audit, and session-claim paths all honor, so a deleted session stays gone (the backend keeps returning the 404 the client relies on to clear the stale route). Genuine crash recovery is unaffected — a session whose sidecar is lost without a delete is still restored — imported external-channel (messaging) sessions are exempt and keep their transcript, and a deleted id is automatically un-tombstoned if the same session is later re-created or re-imported. Thanks @rodboev. (#5504, #5498)
 - **A drag that ends over the sidebar no longer switches conversations by accident.** Releasing the mouse (a stray `pointerup`) over a session row after a drag that began elsewhere in the main content area could switch you into that conversation unintentionally. Session switching now ignores a `pointerup` that isn't a genuine click on the row. Thanks @webtecnica. (#5487, #5462)
 - **Extension gallery downloads no longer hang on networks with broken IPv6.** Gallery installs and registry fetches followed the OS address order (IPv6-first); on a network advertising dead IPv6 routes, every install stalled for the full TCP timeout before falling back to IPv4. Downloads now try IPv4 first (via a non-global, thread-safe per-connection override that preserves the existing redirect allowlist and timeouts), so installs are fast again on such networks. Thanks @rumotoshino. (#5458)
diff --git a/static/boot.js b/static/boot.js
index 634ff11b..3bee6262 100644
--- a/static/boot.js
+++ b/static/boot.js
@@ -1916,6 +1916,28 @@ $('msg').addEventListener('input',()=>{
     hideCmdDropdown();
   }
 });
+// #5514/#5515: re-pin the transcript on ANY composer height change, not only the
+// ones that route through the input->autoResize path. A multi-line paste
+// (WisprFlow), a draft restore, an attachment tray / selection-chip appearing, a
+// programmatic value set, or a font/reflow can all grow the composer and shrink
+// the flex:1 transcript viewport, stranding a pinned reader above the bottom
+// (reads as a "random" upward jump — #5515). Observe the whole #composerWrap
+// (not just #msg) so tray/chip growth is covered too, at one seam. The re-pin is
+// guarded (only fires when genuinely pinned), so it never fights a reader who
+// scrolled away. First callback fires on observe (initial size) — the guard
+// makes that a cheap no-op.
+(()=>{
+  const _cw=$('composerWrap')||$('msg');
+  if(!_cw || typeof ResizeObserver!=='function' || typeof _repinMessagesAfterComposerResize!=='function') return;
+  let _lastComposerH=_cw.offsetHeight;
+  const _ro=new ResizeObserver(()=>{
+    const h=_cw.offsetHeight;
+    if(h<=_lastComposerH){_lastComposerH=h;return;}   // shrink/no-op: enlarges the viewport, can't strand
+    _lastComposerH=h;
+    _repinMessagesAfterComposerResize();               // grow: re-pin the pinned reader
+  });
+  try{ _ro.observe(_cw); }catch(_){ }
+})();
 // Track IME composition for East Asian input. Safari fires the committing
 // keydown AFTER compositionend with isComposing=false, so we also keep a
 // manual flag and reset it on the next tick to swallow that trailing Enter.
diff --git a/static/messages.js b/static/messages.js
index 219c6fca..8d4c378a 100644
--- a/static/messages.js
+++ b/static/messages.js
@@ -6181,9 +6181,18 @@ function autoResize(){
     _composerAutoResizeRaf=0;
   }
   const el=$('msg');
+  const _prevComposerH=el.offsetHeight;
   el.style.height='auto';
   el.style.height=Math.min(el.scrollHeight,200)+'px';
   updateSendBtn();
+  // #5514/#5515: growing the composer shrinks the flex:1 transcript viewport, so
+  // a reader pinned to the bottom would be stranded above it ("scrolls up 1 row
+  // per composer row"). Re-pin the transcript when it's genuinely still pinned —
+  // but only when the composer actually GREW (a shrink enlarges the viewport and
+  // can't strand a reader), so the common no-height-change keystroke skips the
+  // re-pin's DOM read entirely. The #composerWrap ResizeObserver is the safety
+  // net for any growth path that doesn't route through here.
+  if(el.offsetHeight>_prevComposerH && typeof _repinMessagesAfterComposerResize==='function') _repinMessagesAfterComposerResize();
 }
 function scheduleComposerAutoResize(){
   if(typeof requestAnimationFrame!=='function'){autoResize();return;}
diff --git a/static/ui.js b/static/ui.js
index 6af31688..0719a52b 100644
--- a/static/ui.js
+++ b/static/ui.js
@@ -5380,6 +5380,26 @@ function _messageBottomDistance(){
   if(!el) return 0;
   return el.scrollHeight-el.scrollTop-el.clientHeight;
 }
+// #5514/#5515: when the composer grows (typing multiple rows, Shift+Enter, a
+// multi-line paste / WisprFlow), the flex:1 `.messages` viewport shrinks by the
+// same delta. A reader pinned to the bottom is then stranded Δpx above it — the
+// transcript appears to "scroll up" one row per composer row, and (the #5515
+// half) it reads as a random upward jump during normal use. autoResize() only
+// resized the textarea; nothing re-pinned the transcript. Re-pin the bottom, but
+// ONLY when the reader is genuinely still pinned (sticky-unpin model: honor
+// _messageUserUnpinned so we never yank a reader who scrolled away, and never
+// fight a stream that already unpinned). Cheap no-op when not pinned.
+function _repinMessagesAfterComposerResize(){
+  if(_messageUserUnpinned || !_scrollPinned) return;
+  const el=$('messages');
+  if(!el) return;
+  // Already at/very near the bottom? nothing to do (avoids needless writes while
+  // idle-reading a short conversation that isn't scrollable).
+  if(_messageBottomDistance()<=1) return;
+  if(typeof _setMessageScrollToBottom==='function') _setMessageScrollToBottom();
+  else { el.scrollTop=el.scrollHeight; }
+}
+if(typeof window!=='undefined') window._repinMessagesAfterComposerResize=_repinMessagesAfterComposerResize;
 function _shouldFollowMessagesOnDomReplace(){
   // Final stream settlement replaces the live DOM with persisted messages. Keep
   // following only for users who are still pinned or effectively at the tail.
diff --git a/tests/test_issue5514_composer_grow_scroll_pin.py b/tests/test_issue5514_composer_grow_scroll_pin.py
new file mode 100644
index 00000000..e6f5b9ed
--- /dev/null
+++ b/tests/test_issue5514_composer_grow_scroll_pin.py
@@ -0,0 +1,141 @@
+"""Regression coverage for #5514 + #5515 — transcript scrolls up when the composer
+grows while the reader is pinned to the bottom.
+
+#5514 (deterministic): with the chat pinned to the bottom, growing the composer
+(multi-line typing, Shift+Enter, a multi-line / WisprFlow paste) shrinks the
+`flex:1` `.messages` viewport by the same delta, stranding the reader Δpx above
+the bottom — the transcript "scrolls up one row per composer row." autoResize()
+resized the textarea but never re-pinned the transcript.
+
+#5515 (intermittent "random scroll up"): the same class of viewport-shrink from
+composer growth via paths that don't route through the input->autoResize seam
+(paste, draft restore, programmatic value set, reflow) reads to the user as a
+random upward jump.
+
+Fix: `_repinMessagesAfterComposerResize()` (static/ui.js) re-pins the transcript
+to the bottom ONLY when the reader is genuinely still pinned (honors
+`_messageUserUnpinned` / `_scrollPinned` so a reader who scrolled away is never
+yanked back). It is called (a) from autoResize() and (b) from a ResizeObserver on
+the #composerWrap wrapper that catches every height-change path (typed input,
+paste, draft restore, attachment tray / selection chip).
+
+This module verifies BOTH the static wiring and the helper's guard logic via a
+node `vm` sandbox that reproduces the pinned-vs-unpinned viewport-shrink scenario.
+"""
+import json
+import shutil
+import subprocess
+import textwrap
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).parents[1]
+UI_JS = (ROOT / "static" / "ui.js").read_text(encoding="utf-8")
+MESSAGES_JS = (ROOT / "static" / "messages.js").read_text(encoding="utf-8")
+BOOT_JS = (ROOT / "static" / "boot.js").read_text(encoding="utf-8")
+
+
+# ---------------------------------------------------------------------------
+# Static wiring
+# ---------------------------------------------------------------------------
+
+def _helper_body() -> str:
+    start = UI_JS.find("function _repinMessagesAfterComposerResize(")
+    assert start != -1, "the _repinMessagesAfterComposerResize helper must exist in ui.js"
+    end = UI_JS.find("\nif(typeof window!=='undefined') window._repinMessagesAfterComposerResize", start)
+    assert end != -1, "helper must be immediately followed by its window export"
+    return UI_JS[start:end]
+
+
+def test_helper_exists_and_is_pin_guarded():
+    body = _helper_body()
+    # Never re-pin a reader who scrolled away (sticky-unpin model).
+    assert "if(_messageUserUnpinned || !_scrollPinned) return;" in body
+    # Uses the canonical bottom-pin primitive.
+    assert "_setMessageScrollToBottom" in body
+    # Cheap no-op when already at bottom.
+    assert "<=1) return;" in body
+
+
+def test_autoresize_calls_the_repin():
+    start = MESSAGES_JS.find("function autoResize(")
+    assert start != -1
+    end = MESSAGES_JS.find("function scheduleComposerAutoResize(", start)
+    assert end > start
+    body = MESSAGES_JS[start:end]
+    # The height write must still be there...
+    assert "el.style.height=Math.min(el.scrollHeight,200)+'px'" in body
+    # ...and the re-pin must be called after it, guarded so it only fires when the
+    # composer actually grew (skips the DOM read on a no-height-change keystroke).
+    assert "_repinMessagesAfterComposerResize()" in body
+    assert "el.offsetHeight>_prevComposerH" in body
+
+
+def test_resize_observer_installed_on_composer():
+    # A ResizeObserver on the composer wrapper re-pins on grow (catches
+    # tray/chip/paste height changes, not just the typed-input seam).
+    assert "new ResizeObserver(" in BOOT_JS
+    assert "_repinMessagesAfterComposerResize" in BOOT_JS
+    # Observes the whole wrapper so attach-tray / selection-chip growth is covered.
+    assert "$('composerWrap')" in BOOT_JS
+    # Only re-pin on GROW (a shrink enlarges the viewport, can't strand a reader).
+    assert "can't strand" in BOOT_JS
+
+
+# ---------------------------------------------------------------------------
+# Behavioral (node vm) — the pin guard under a viewport shrink
+# ---------------------------------------------------------------------------
+
+def _run(scenario):
+    node = shutil.which("node")
+    if not node:  # pragma: no cover
+        pytest.skip("node not available")
+    body = _helper_body()
+    harness = textwrap.dedent(
+        """
+        // Minimal DOM/scroll-state stub reproducing the composer-grow viewport shrink.
+        let _messageUserUnpinned = %(unpinned)s;
+        let _scrollPinned = %(pinned)s;
+        // messages pane: scrollHeight fixed; clientHeight shrinks when composer grows.
+        const el = { scrollHeight: 8768, clientHeight: 745, scrollTop: %(scrolltop)s };
+        const $ = (id) => (id === 'messages' ? el : null);
+        function _messageBottomDistance(){ return el.scrollHeight - el.scrollTop - el.clientHeight; }
+        function _setMessageScrollToBottom(){ el.scrollTop = el.scrollHeight - el.clientHeight; el._pinnedCalled = true; }
+
+        %(helper)s
+
+        // Simulate the composer growing by 132px: the viewport shrinks.
+        el.clientHeight -= 132;
+        _repinMessagesAfterComposerResize();
+        const bottomDist = el.scrollHeight - el.scrollTop - el.clientHeight;
+        console.log(JSON.stringify({ scrollTop: el.scrollTop, bottomDist, pinnedCalled: !!el._pinnedCalled }));
+        """
+    ) % {**scenario, "helper": body}
+    proc = subprocess.run([node, "-e", harness], capture_output=True, text=True, timeout=30)
+    assert proc.returncode == 0, f"node harness failed: {proc.stderr}"
+    return json.loads(proc.stdout.strip())
+
+
+def test_pinned_reader_is_repinned_after_composer_grow():
+    # Reader pinned to bottom (scrollTop at old max = 8768-745 = 8023), composer
+    # grows -> viewport shrinks -> must re-pin so bottomDist returns to 0.
+    out = _run({"unpinned": "false", "pinned": "true", "scrolltop": 8023})
+    assert out["pinnedCalled"] is True
+    assert out["bottomDist"] == 0, f"pinned reader must be re-pinned to the bottom; got {out}"
+
+
+def test_unpinned_reader_is_not_yanked_down():
+    # Reader scrolled up (unpinned). Composer grow must NOT re-pin — no yank.
+    out = _run({"unpinned": "true", "pinned": "false", "scrolltop": 3000})
+    assert out["pinnedCalled"] is False
+    assert out["scrollTop"] == 3000, f"unpinned reader must not be moved; got {out}"
+
+
+def test_pinned_but_already_at_bottom_is_a_noop():
+    # scrollTop already exactly at the (post-shrink) bottom -> nothing to do.
+    # scrollHeight 8768, clientHeight after shrink 613 -> bottom scrollTop = 8155.
+    out = _run({"unpinned": "false", "pinned": "true", "scrolltop": 8155})
+    # bottomDist is already <=1 at call time (8768-8155-613 = 0), so no re-pin call.
+    assert out["pinnedCalled"] is False
+    assert out["bottomDist"] == 0