diff --git a/acp_adapter/session.py b/acp_adapter/session.py
index 6e16016a6b3bb..ce6843ab6234c 100644
--- a/acp_adapter/session.py
+++ b/acp_adapter/session.py
@@ -56,7 +56,18 @@ def _normalize_cwd_for_compare(cwd: str | None) -> str:
     elif re.match(r"^/mnt/[A-Za-z]/", expanded):
         expanded = f"/mnt/{expanded[5].lower()}/{expanded[7:]}"
 
-    return os.path.normpath(expanded)
+    # Resolve symlink aliases so equivalent spellings of the same directory
+    # compare equal — macOS reports editor workspaces as ``/var/...`` while
+    # sessions get stored under ``/private/var/...`` (and ``/tmp`` vs
+    # ``/private/tmp``), which made ACP history filters silently drop a
+    # workspace's own sessions. ``os.path.realpath`` is lexical for missing
+    # paths (strict=False), so cwds that don't exist on this host — e.g.
+    # WSL-translated Windows drives — keep the previous normpath behavior.
+    # Ported from PrimeIntellect-ai/prime-agent#628.
+    try:
+        return os.path.realpath(expanded)
+    except OSError:
+        return os.path.normpath(expanded)
 
 
 def _build_session_title(title: Any, preview: Any, cwd: str | None) -> str:
diff --git a/tests/acp/test_session.py b/tests/acp/test_session.py
index 88d2a27998e62..3d8bc1908909b 100644
--- a/tests/acp/test_session.py
+++ b/tests/acp/test_session.py
@@ -158,6 +158,54 @@ class TestWslCwdTranslation:
 # ---------------------------------------------------------------------------
 
 
+class TestSymlinkAliasNormalization:
+    """Ported from PrimeIntellect-ai/prime-agent#628 — symlink aliases of the
+    same directory (macOS ``/var`` vs ``/private/var``, ``/tmp`` vs
+    ``/private/tmp``) must compare equal, or ACP history filters silently drop
+    a workspace's own sessions."""
+
+    def test_symlink_alias_compares_equal(self, tmp_path):
+        real = tmp_path / "real"
+        real.mkdir()
+        alias = tmp_path / "alias"
+        alias.symlink_to(real)
+        assert acp_session._normalize_cwd_for_compare(
+            str(alias)
+        ) == acp_session._normalize_cwd_for_compare(str(real))
+
+    def test_distinct_dirs_still_compare_different(self, tmp_path):
+        a = tmp_path / "a"
+        b = tmp_path / "b"
+        a.mkdir()
+        b.mkdir()
+        assert acp_session._normalize_cwd_for_compare(
+            str(a)
+        ) != acp_session._normalize_cwd_for_compare(str(b))
+
+    def test_missing_path_keeps_lexical_normalization(self):
+        # realpath(strict=False) is lexical for nonexistent paths, so cwds
+        # that don't exist on this host (e.g. WSL-translated drives) behave
+        # exactly as the old normpath comparison did.
+        assert acp_session._normalize_cwd_for_compare(
+            "/nonexistent-hermes-test/x/../y"
+        ) == "/nonexistent-hermes-test/y"
+
+    def test_list_sessions_matches_symlink_alias_cwd(self, manager, tmp_path):
+        real = tmp_path / "proj"
+        real.mkdir()
+        alias = tmp_path / "link"
+        alias.symlink_to(real)
+        state = manager.create_session(cwd=str(real))
+        state.history.append({"role": "user", "content": "hello"})
+        listed = manager.list_sessions(cwd=str(alias))
+        assert [s["session_id"] for s in listed] == [state.session_id]
+
+
+# ---------------------------------------------------------------------------
+# list / cleanup
+# ---------------------------------------------------------------------------
+
+
 class TestListAndCleanup:
     def test_list_sessions_empty(self, manager):
         assert manager.list_sessions() == []