diff --git a/collins/prefs.py b/collins/prefs.py
index b37208b..d0ef542 100644
--- a/collins/prefs.py
+++ b/collins/prefs.py
@@ -249,6 +249,16 @@ def __init__(self, state: AppState, on_change: Callable[[], None]) -> None:
         self._auto_title_row.set_active(bool(state.get_setting("auto_title_sessions")))
         self._auto_title_row.connect("notify::active", self._on_auto_title_changed)
         sidebar_group.add(self._auto_title_row)
+        self._pr_title_row = Adw.SwitchRow(
+            title=_("Rename sessions after their pull requests"),
+            subtitle=_(
+                "Retitle a session to match the newest pull request opened "
+                "in it; manually renamed sessions keep their name"
+            ),
+        )
+        self._pr_title_row.set_active(bool(state.get_setting("pr_title_sessions")))
+        self._pr_title_row.connect("notify::active", self._on_pr_title_changed)
+        sidebar_group.add(self._pr_title_row)
         page.add(sidebar_group)
 
         self._footer_apps_group = Adw.PreferencesGroup(
@@ -559,6 +569,10 @@ def _on_auto_title_changed(self, row: Adw.SwitchRow, _pspec) -> None:
         self._state.set_setting("auto_title_sessions", row.get_active())
         self._on_change()
 
+    def _on_pr_title_changed(self, row: Adw.SwitchRow, _pspec) -> None:
+        self._state.set_setting("pr_title_sessions", row.get_active())
+        self._on_change()
+
     def _on_worktree_changed(self, row: Adw.SwitchRow, _pspec) -> None:
         self._state.set_setting("worktree_new_sessions", row.get_active())
         self._on_change()
diff --git a/collins/prstatus.py b/collins/prstatus.py
index ae8fee1..33ebea4 100644
--- a/collins/prstatus.py
+++ b/collins/prstatus.py
@@ -425,6 +425,19 @@ def from_records(records: object) -> list[PullRequest]:
     return [pr for record in records if (pr := from_record(record)) is not None]
 
 
+def newest_title(records: object) -> str | None:
+    """The newest saved PR's title, or None while no saved PR has one.
+
+    What the pr_title_sessions setting renames a session to (see
+    SessionStore.apply_pr_title). A saved list is oldest-first, so the last
+    titled entry is the PR the session opened most recently; a PR whose title
+    hasn't arrived from `gh` yet (a bare pr-link, say) contributes nothing
+    until a refresh lands one.
+    """
+    titles = [pr.title for pr in from_records(records) if pr.title]
+    return titles[-1] if titles else None
+
+
 def _load_cache() -> dict:
     """The whole gh PR status cache, or {} when it is missing or unusable."""
     try:
diff --git a/collins/sidebar.py b/collins/sidebar.py
index 36e4310..f649af1 100644
--- a/collins/sidebar.py
+++ b/collins/sidebar.py
@@ -1,6 +1,6 @@
 # Modified from the original agent-session-manager
 # (https://github.com/r4nd3l/agent-session-manager, GPL-3.0) in the ghackett
-# fork. Last modified: 2026-08-02. Full change history: git log for this file.
+# fork. Last modified: 2026-08-03. Full change history: git log for this file.
 
 """Session sidebar: search, project accordion, favorites, selection mode.
 
@@ -613,6 +613,7 @@ def _pr_menu_refreshed(self, token: int, prs: list[PullRequest]) -> bool:
             return GLib.SOURCE_REMOVE
         self._prs = prs
         self._sidebar.store.state.set_session_prs(self.item.session_id, to_records(prs))
+        self._sidebar.store.apply_pr_title(self.item.session_id)
         if self._pr_menu.get_visible():
             prmenu.update(self._pr_menu, prs, self._pr_host)
         return GLib.SOURCE_REMOVE
diff --git a/collins/state.py b/collins/state.py
index 9e019e6..833ab77 100644
--- a/collins/state.py
+++ b/collins/state.py
@@ -60,6 +60,10 @@ def _migrate_old_config() -> None:
     # the env half only takes effect for tabs opened after a change.
     "progress_termprop": True,
     "auto_title_sessions": True,  # summarize each new session's first prompt into a short title
+    # Retitle a session to its newest pull request's title as PRs are
+    # detected (see SessionStore.apply_pr_title). Fills the generated-name
+    # slot, so a manual rename always wins.
+    "pr_title_sessions": False,
     # Launch new sessions with the agent CLI's worktree flag (claude -w) in
     # git projects, isolating their edits from the live checkout. Per-project
     # overrides live in AppState.project_worktree.
diff --git a/collins/store.py b/collins/store.py
index e9f4250..992c589 100644
--- a/collins/store.py
+++ b/collins/store.py
@@ -1,6 +1,6 @@
 # Modified from the original agent-session-manager
 # (https://github.com/r4nd3l/agent-session-manager, GPL-3.0) in the ghackett
-# fork. Last modified: 2026-08-02. Full change history: git log for this file.
+# fork. Last modified: 2026-08-03. Full change history: git log for this file.
 
 """SessionStore: the single source of truth between disk and UI.
 
@@ -24,6 +24,7 @@
 from .i18n import _
 from .models import CHATS_GROUP, FAV_GROUP, SessionItem
 from .providers import available_providers
+from .prstatus import newest_title
 from .sessions import (
     Session,
     discover_sessions,
@@ -109,6 +110,9 @@ def __init__(self, state: AppState) -> None:
         self._last_sessions: list[Session] = []
         self._first_scan = True
         self._regen_pending: set[str] = set()  # ids whose regen should replace a manual name
+        # Last-seen pr_title_sessions value, so apply_pr_titles sweeps only
+        # when the setting flips on rather than on every preferences apply.
+        self._pr_titles_on = bool(state.get_setting("pr_title_sessions"))
         self._monitors: list[Gio.FileMonitor] = []
         self._refresh_queued = False
         self._scanning = False
@@ -441,6 +445,45 @@ def rename(self, session_id: str, name: str) -> None:
         self.state.set_name(session_id, name)
         self._apply()
 
+    def apply_pr_title(self, session_id: str) -> None:
+        """Retitle *session_id* after the newest PR it has opened.
+
+        The whole pr_title_sessions setting: called wherever a session's
+        saved PR list is (re)written — a tab's poll, the sidebar's PR menu —
+        and a no-op until one of those lands a titled record. Writes the
+        generated-name slot, so a manual rename still wins in display_name
+        and the auto-title paths already know to skip the session.
+        """
+        if not self.state.get_setting("pr_title_sessions"):
+            return
+        title = newest_title(self.state.get_session_prs(session_id))
+        if not title or title == self.state.get_generated_name(session_id):
+            return
+        self.state.set_generated_name(session_id, title)
+        self._apply()
+
+    def apply_pr_titles(self) -> None:
+        """The catch-up half of pr_title_sessions: every known session at
+        once, for when the setting is switched on with PRs already saved.
+
+        Called on every preferences apply — that's the only signal there is —
+        so the off→on flip is detected here: a save that didn't just flip the
+        setting returns without walking a thing. While the setting stays on,
+        apply_pr_title at each detection site is what keeps names current.
+        """
+        on = bool(self.state.get_setting("pr_title_sessions"))
+        was_on, self._pr_titles_on = self._pr_titles_on, on
+        if not on or was_on:
+            return
+        names: dict[str, str] = {}
+        for session_id in self.sessions:
+            title = newest_title(self.state.get_session_prs(session_id))
+            if title and title != self.state.get_generated_name(session_id):
+                names[session_id] = title
+        if names:
+            self.state.set_generated_names(names)
+            self._apply()
+
     def toggle_favorite(self, session_id: str) -> None:
         self.state.toggle_favorite(session_id)
         self._apply()
diff --git a/collins/window.py b/collins/window.py
index b672360..e04bde6 100644
--- a/collins/window.py
+++ b/collins/window.py
@@ -1,6 +1,6 @@
 # Modified from the original agent-session-manager
 # (https://github.com/r4nd3l/agent-session-manager, GPL-3.0) in the ghackett
-# fork. Last modified: 2026-08-02. Full change history: git log for this file.
+# fork. Last modified: 2026-08-03. Full change history: git log for this file.
 """Main window: composes the session sidebar with the tabbed terminal area."""
 
 from __future__ import annotations
@@ -1588,6 +1588,7 @@ def _on_tab_prs_changed(self, tab: TerminalTab, records: object) -> None:
             return
         self.state.set_session_prs(tab.session_id, list(records or []))
         self.sidebar.sync_session_prs(tab.session_id)
+        self.store.apply_pr_title(tab.session_id)
 
     def _on_panel_size_changed(self, _tab: TerminalTab, mode: str, size: int) -> None:
         """A divider was dragged: remember the size app-wide, so every panel
@@ -3609,6 +3610,7 @@ def _apply_preferences(self) -> None:
         self.sidebar.refresh_usage_panel()
         self.sidebar.refresh_project_icon_size()
         self._bg_status.set_polling(bool(self.state.get_setting("background_status_poll")))
+        self.store.apply_pr_titles()
 
     def _apply_settings_to_tabs(self) -> None:
         for i in range(self.tab_view.get_n_pages()):
diff --git a/po/collins.pot b/po/collins.pot
index 866d942..d8966c0 100644
--- a/po/collins.pot
+++ b/po/collins.pot
@@ -443,6 +443,16 @@ msgid ""
 "prompt"
 msgstr ""
 
+#: collins/prefs.py:253
+msgid "Rename sessions after their pull requests"
+msgstr ""
+
+#: collins/prefs.py:255
+msgid ""
+"Retitle a session to match the newest pull request opened in it; manually "
+"renamed sessions keep their name"
+msgstr ""
+
 #: collins/prefs.py:190 collins/prefs.py:196
 msgid "Language"
 msgstr ""
diff --git a/tests/test_prstatus.py b/tests/test_prstatus.py
index c4d721a..3c4cf7b 100644
--- a/tests/test_prstatus.py
+++ b/tests/test_prstatus.py
@@ -25,6 +25,7 @@
     invalidate,
     menu_name,
     merge_ordered,
+    newest_title,
     parse_pr_link,
     refresh,
     resync,
@@ -830,6 +831,31 @@ def test_from_records_tolerates_junk_in_place_of_a_list():
     assert from_records({"number": 55, "url": URL}) == []
 
 
+def test_newest_title_is_the_last_titled_records():
+    """Two titled PRs: the later one is what the session gets renamed to."""
+    records = [
+        {"number": 40, "url": "https://github.com/episode6/collins/pull/40", "title": "Old work"},
+        {"number": 55, "url": URL, "title": "New work"},
+    ]
+    assert newest_title(records) == "New work"
+
+
+def test_newest_title_skips_untitled_records():
+    """A fresh pr-link has no title until gh answers; it must not blank the
+    name a titled predecessor already provided."""
+    records = [
+        {"number": 40, "url": "https://github.com/episode6/collins/pull/40", "title": "Old work"},
+        {"number": 55, "url": URL},
+    ]
+    assert newest_title(records) == "Old work"
+
+
+def test_newest_title_none_without_any_title():
+    assert newest_title([{"number": 55, "url": URL}]) is None
+    assert newest_title([]) is None
+    assert newest_title("junk") is None
+
+
 # -- merge_ordered (saved list + transcript links) --------------------------
 
 
diff --git a/tests/test_state.py b/tests/test_state.py
index adfe885..07109c2 100644
--- a/tests/test_state.py
+++ b/tests/test_state.py
@@ -1,6 +1,6 @@
 # Modified from the original agent-session-manager
 # (https://github.com/r4nd3l/agent-session-manager, GPL-3.0) in the ghackett
-# fork. Last modified: 2026-08-02. Full change history: git log for this file.
+# fork. Last modified: 2026-08-03. Full change history: git log for this file.
 
 import json
 
@@ -90,6 +90,13 @@ def test_defaults_for_unknown_settings(app_state):
     assert state.get_setting("font") == ""
 
 
+def test_pr_title_sessions_setting(app_state):
+    state = app_state.AppState()
+    assert state.get_setting("pr_title_sessions") is False  # opt-in only
+    state.set_setting("pr_title_sessions", True)
+    assert app_state.AppState().get_setting("pr_title_sessions") is True
+
+
 def test_caffeine_on_launch_setting(app_state):
     state = app_state.AppState()
     assert state.get_setting("caffeine_on_launch") is False  # opt-in only
diff --git a/tests/test_store.py b/tests/test_store.py
index 4af3d7e..d8bd4b5 100644
--- a/tests/test_store.py
+++ b/tests/test_store.py
@@ -525,3 +525,88 @@ def test_rows_representing_holds_a_mid_chain_fork_during_a_second_handoff(store)
     store.record_forward(first_fork, second_fork)
     assert store.rows_representing(first_fork) == [original]
     assert store.rows_representing(second_fork) == [original]
+
+
+# -- apply_pr_title (the pr_title_sessions setting) -------------------------
+
+
+def _titled_pr(number, title=None):
+    record = {"number": number, "url": f"https://github.com/episode6/collins/pull/{number}"}
+    if title:
+        record["title"] = title
+    return record
+
+
+def test_apply_pr_title_is_off_by_default(store):
+    session_id = store._last_sessions[0].session_id
+    store.state.set_session_prs(session_id, [_titled_pr(55, "Add the thing")])
+    store.apply_pr_title(session_id)
+    assert store.state.get_generated_name(session_id) is None
+
+
+def test_apply_pr_title_renames_to_the_newest_titled_pr(store):
+    store.state.set_setting("pr_title_sessions", True)
+    session = store._last_sessions[0]
+    store.state.set_session_prs(
+        session.session_id, [_titled_pr(40, "Old work"), _titled_pr(55, "Add the thing")]
+    )
+    store.apply_pr_title(session.session_id)
+    assert store.state.get_generated_name(session.session_id) == "Add the thing"
+    assert store.display_name(session) == "Add the thing"
+
+
+def test_apply_pr_title_waits_for_a_title(store):
+    """A bare pr-link record has no title until gh answers; nothing to do yet."""
+    store.state.set_setting("pr_title_sessions", True)
+    session_id = store._last_sessions[0].session_id
+    store.state.set_generated_name(session_id, "Auto title")
+    store.state.set_session_prs(session_id, [_titled_pr(55)])
+    store.apply_pr_title(session_id)
+    assert store.state.get_generated_name(session_id) == "Auto title"
+
+
+def test_apply_pr_title_loses_to_a_manual_rename(store):
+    store.state.set_setting("pr_title_sessions", True)
+    session = store._last_sessions[0]
+    store.rename(session.session_id, "My name")
+    store.state.set_session_prs(session.session_id, [_titled_pr(55, "Add the thing")])
+    store.apply_pr_title(session.session_id)
+    # The generated slot is written, but the manual name keeps winning.
+    assert store.state.get_generated_name(session.session_id) == "Add the thing"
+    assert store.display_name(session) == "My name"
+
+
+def test_apply_pr_titles_sweeps_saved_prs_when_switched_on(store):
+    """Turning the setting on retitles sessions whose PRs are already saved."""
+    first, second = store._last_sessions[0], store._last_sessions[1]
+    store.state.set_session_prs(first.session_id, [_titled_pr(55, "Add the thing")])
+    store.state.set_session_prs(second.session_id, [_titled_pr(56)])  # no title yet
+    store.apply_pr_titles()  # setting still off: a no-op
+    assert store.state.get_generated_name(first.session_id) is None
+
+    store.state.set_setting("pr_title_sessions", True)
+    store.apply_pr_titles()
+    assert store.state.get_generated_name(first.session_id) == "Add the thing"
+    assert store.state.get_generated_name(second.session_id) is None
+
+
+def test_apply_pr_titles_sweeps_only_on_the_off_to_on_flip(store):
+    """Preferences apply calls the sweep on every save; only the save that
+    flips the setting on walks the sessions — steady-state names are the
+    per-detection apply_pr_title's job."""
+    first = store._last_sessions[0]
+    store.state.set_setting("pr_title_sessions", True)
+    store.apply_pr_titles()  # off at construction, on now: the flip
+
+    # A list saved behind the sweep's back: a later steady-state apply (the
+    # user changed the font, say) must not pick it up.
+    store.state.set_session_prs(first.session_id, [_titled_pr(55, "Add the thing")])
+    store.apply_pr_titles()
+    assert store.state.get_generated_name(first.session_id) is None
+
+    # Off and back on is a fresh flip, and a fresh catch-up.
+    store.state.set_setting("pr_title_sessions", False)
+    store.apply_pr_titles()
+    store.state.set_setting("pr_title_sessions", True)
+    store.apply_pr_titles()
+    assert store.state.get_generated_name(first.session_id) == "Add the thing"