diff --git a/hermes_cli/main.py b/hermes_cli/main.py
index 822cd2a09d..8e43f0ffa0 100644
--- a/hermes_cli/main.py
+++ b/hermes_cli/main.py
@@ -13311,6 +13311,36 @@ def main():
     sessions_rename.add_argument("session_id", help="Session ID to rename")
     sessions_rename.add_argument("title", nargs="+", help="New title for the session")
 
+    sessions_pin = sessions_subparsers.add_parser(
+        "pin",
+        help="Pin session(s) — durable keep flag, exempt from auto-archive",
+        description=(
+            "Set the durable 'keep' flag on one or more sessions. Pinned "
+            "sessions are exempt from the sessions.auto_archive stale sweep "
+            "and always appear in listings. The same flag drives the Desktop "
+            "sidebar's Pinned section — pin from either surface, both see it."
+        ),
+    )
+    sessions_pin.add_argument(
+        "session_ids", nargs="+", help="Session ID(s) or unique prefix(es) to pin"
+    )
+
+    sessions_unpin = sessions_subparsers.add_parser(
+        "unpin", help="Remove the pin (durable keep flag) from session(s)"
+    )
+    sessions_unpin.add_argument(
+        "session_ids", nargs="+", help="Session ID(s) or unique prefix(es) to unpin"
+    )
+
+    sessions_pinned = sessions_subparsers.add_parser(
+        "pinned", help="List pinned sessions"
+    )
+    sessions_pinned.add_argument(
+        "--json",
+        action="store_true",
+        help="Emit machine-readable JSON (for backup/restore scripting)",
+    )
+
     sessions_retitle = sessions_subparsers.add_parser(
         "retitle-skills",
         help="Re-title sessions whose auto-title came from a /skill's own text",
diff --git a/hermes_cli/sessions_cmd.py b/hermes_cli/sessions_cmd.py
index f0a039ce5e..da8a2bdda0 100644
--- a/hermes_cli/sessions_cmd.py
+++ b/hermes_cli/sessions_cmd.py
@@ -1023,6 +1023,69 @@ def cmd_sessions(args, sessions_parser=None):
         except ValueError as e:
             print(f"Error: {e}")
 
+    elif action in ("pin", "unpin"):
+        # CLI surface for the durable "keep" flag (issue #52955). Pinned
+        # sessions are exempt from the sessions.auto_archive stale sweep and
+        # always surface in listings; until now only the Desktop sidebar
+        # could write the flag. Inspired by Perplexity Computer's
+        # conversational session management (pin/archive from any surface):
+        # pin state is operational infrastructure, so every surface — GUI,
+        # TUI, CLI, scripts — needs read/write access to the same store.
+        pinning = action == "pin"
+        failures = 0
+        for raw_id in args.session_ids:
+            resolved = db.resolve_session_id(raw_id)
+            if not resolved:
+                print(f"Session '{raw_id}' not found.")
+                failures += 1
+                continue
+            if db.set_session_pinned(resolved, pinning):
+                verb = "Pinned" if pinning else "Unpinned"
+                title = db.get_session_title(resolved)
+                suffix = f"  ({title})" if title else ""
+                print(f"{verb} session '{resolved}'.{suffix}")
+            else:
+                print(f"Session '{raw_id}' not found.")
+                failures += 1
+        if failures:
+            return 1
+
+    elif action == "pinned":
+        # List every pinned conversation regardless of age. limit=1 keeps the
+        # recency page minimal; include_pinned back-fills ALL pinned rows the
+        # page missed (bounded by pin count, see list_sessions_rich), so old
+        # pins can't fall off a paging window.
+        rows = db.list_sessions_rich(
+            limit=1, include_pinned=True, exclude_sources=_exclude
+        )
+        pinned_rows = [s for s in rows if s.get("pinned")]
+        if getattr(args, "json", False):
+            payload = [
+                {
+                    "id": s["id"],
+                    "title": s.get("title"),
+                    "source": s.get("source"),
+                    "last_active": s.get("last_active"),
+                    "message_count": s.get("message_count"),
+                }
+                for s in pinned_rows
+            ]
+            print(_json.dumps(payload, indent=2))
+            return
+        if not pinned_rows:
+            print(
+                "No pinned sessions. Pin one with: hermes sessions pin <session_id>"
+            )
+            return
+        print(f"{'Title':<32} {'Last Active':<13} {'Src':<9} {'ID'}")
+        print("─" * 100)
+        for s in pinned_rows:
+            title = (s.get("title") or s.get("preview", "") or "—")[:30]
+            last_active = _relative_time(s.get("last_active"))
+            print(
+                f"{title:<32} {last_active:<13} {(s.get('source') or '-'):<9} {s['id']}"
+            )
+
     elif action == "retitle-skills":
         from agent.skill_commands import describe_skill_invocation
         from agent.title_generator import generate_title
diff --git a/tests/hermes_cli/test_sessions_pin.py b/tests/hermes_cli/test_sessions_pin.py
new file mode 100644
index 0000000000..aa4c3b0b79
--- /dev/null
+++ b/tests/hermes_cli/test_sessions_pin.py
@@ -0,0 +1,138 @@
+"""CLI pin / unpin / pinned subcommands (issue #52955).
+
+Pin state is the durable "keep" flag in state.db that the Desktop sidebar
+writes; these tests pin the CLI's read/write access to the SAME store
+(SessionDB.set_session_pinned / list_sessions_rich(include_pinned=True)),
+not a client-local list.
+"""
+
+import json
+import sys
+
+
+class _FakeDB:
+    def __init__(self, rows=None, known=("20260315_092437_c9a6ff",)):
+        self.rows = rows or []
+        self.known = set(known)
+        self.pin_calls = []
+        self.list_kwargs = None
+        self.closed = False
+
+    def resolve_session_id(self, session_id):
+        for k in self.known:
+            if k.startswith(session_id):
+                return k
+        return None
+
+    def set_session_pinned(self, session_id, pinned):
+        self.pin_calls.append((session_id, pinned))
+        return session_id in self.known
+
+    def get_session_title(self, session_id):
+        return "Alpha Work" if session_id in self.known else None
+
+    def list_sessions_rich(self, **kwargs):
+        self.list_kwargs = kwargs
+        return self.rows
+
+    def close(self):
+        self.closed = True
+
+
+def _run(monkeypatch, capsys, argv_tail, db):
+    import hermes_cli.main as main_mod
+    import hermes_state
+
+    monkeypatch.setattr(hermes_state, "SessionDB", lambda: db)
+    monkeypatch.setattr(sys, "argv", ["hermes", "sessions", *argv_tail])
+    try:
+        main_mod.main()
+        code = 0
+    except SystemExit as e:  # non-zero exits propagate through main()
+        code = e.code or 0
+    return code, capsys.readouterr().out
+
+
+def test_pin_accepts_unique_prefix(monkeypatch, capsys):
+    db = _FakeDB()
+    code, out = _run(monkeypatch, capsys, ["pin", "20260315_092437"], db)
+    assert db.pin_calls == [("20260315_092437_c9a6ff", True)]
+    assert "Pinned session '20260315_092437_c9a6ff'." in out
+    assert "(Alpha Work)" in out
+    assert code == 0
+
+
+def test_unpin_writes_false(monkeypatch, capsys):
+    db = _FakeDB()
+    _code, out = _run(monkeypatch, capsys, ["unpin", "20260315_092437_c9a6ff"], db)
+    assert db.pin_calls == [("20260315_092437_c9a6ff", False)]
+    assert "Unpinned session" in out
+
+
+def test_pin_multiple_ids_one_missing(monkeypatch, capsys):
+    db = _FakeDB(known=("aaa111", "bbb222"))
+    code, out = _run(monkeypatch, capsys, ["pin", "aaa", "nope", "bbb"], db)
+    assert ("aaa111", True) in db.pin_calls
+    assert ("bbb222", True) in db.pin_calls
+    assert "Session 'nope' not found." in out
+    assert code == 1
+
+
+def test_pinned_lists_only_pinned_rows(monkeypatch, capsys):
+    rows = [
+        {
+            "id": "pinned_one",
+            "title": "Keep Me",
+            "source": "cli",
+            "last_active": 1_700_000_000.0,
+            "message_count": 3,
+            "pinned": 1,
+        },
+        {
+            "id": "recent_unpinned",
+            "title": "Recent",
+            "source": "cli",
+            "last_active": 1_700_000_100.0,
+            "message_count": 5,
+            "pinned": 0,
+        },
+    ]
+    db = _FakeDB(rows=rows)
+    _code, out = _run(monkeypatch, capsys, ["pinned"], db)
+    # include_pinned back-fill is what guarantees old pins surface
+    assert db.list_kwargs["include_pinned"] is True
+    assert "pinned_one" in out
+    assert "Keep Me" in out
+    assert "recent_unpinned" not in out
+
+
+def test_pinned_json_output(monkeypatch, capsys):
+    rows = [
+        {
+            "id": "pinned_one",
+            "title": "Keep Me",
+            "source": "cli",
+            "last_active": 1_700_000_000.0,
+            "message_count": 3,
+            "pinned": 1,
+        },
+    ]
+    db = _FakeDB(rows=rows)
+    _code, out = _run(monkeypatch, capsys, ["pinned", "--json"], db)
+    payload = json.loads(out)
+    assert payload == [
+        {
+            "id": "pinned_one",
+            "title": "Keep Me",
+            "source": "cli",
+            "last_active": 1_700_000_000.0,
+            "message_count": 3,
+        }
+    ]
+
+
+def test_pinned_empty_hint(monkeypatch, capsys):
+    db = _FakeDB(rows=[])
+    _code, out = _run(monkeypatch, capsys, ["pinned"], db)
+    assert "No pinned sessions" in out
+    assert "hermes sessions pin" in out
diff --git a/website/docs/user-guide/sessions.md b/website/docs/user-guide/sessions.md
index 2c8fc4bbb8..0b62c69f71 100644
--- a/website/docs/user-guide/sessions.md
+++ b/website/docs/user-guide/sessions.md
@@ -462,6 +462,28 @@ hermes sessions rename 20250305_091523_a1b2c3d4 debugging auth flow
 
 If the title is already in use by another session, an error is shown.
 
+### Pin a Session
+
+Pinning sets a durable "keep" flag: pinned sessions are exempt from the
+`sessions.auto_archive` stale sweep and always appear in listings. It is the
+same flag the Desktop sidebar's Pinned section uses — pin from either surface
+and both see it.
+
+```bash
+# Pin one or more sessions (unique ID prefixes work)
+hermes sessions pin 20250305_091523_a1b2c3d4
+hermes sessions pin 20250305 20250306
+
+# Remove the pin
+hermes sessions unpin 20250305_091523_a1b2c3d4
+
+# List pinned sessions
+hermes sessions pinned
+
+# Machine-readable output, e.g. for a nightly backup of your pin set
+hermes sessions pinned --json > pinned-sessions.json
+```
+
 ### Prune Old Sessions
 
 ```bash