diff --git a/tests/honcho_plugin/test_client_identity_isolation.py b/tests/honcho_plugin/test_client_identity_isolation.py
new file mode 100644
index 0000000000..2d87c4b3ed
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+++ b/tests/honcho_plugin/test_client_identity_isolation.py
@@ -0,0 +1,314 @@
+"""Multi-profile client isolation tests.
+
+Pin the cross-tenant bleed class (#69123 multiplexed gateway, #74065
+dashboard): a process-wide first-config-wins client singleton baked the
+first profile's workspace_id and bearer into one shared client, so every
+later profile's memory landed in the first profile's workspace.
+
+The tests drive the REAL resolution chain — HonchoClientConfig.from_global_config
+against real honcho.json files under temp HERMES_HOMEs, with the same
+ContextVar override the gateway multiplexer / dashboard use — and assert
+client identity, not internals.
+
+The two-profile repro mirrors issue #69123's minimal in-process repro;
+per-config-identity caching was first proposed in #69142 (NaMinhyeok) and
+extended in #81401 (angel12).
+"""
+
+import json
+import threading
+
+import pytest
+
+import plugins.memory.honcho.client as client_mod
+from hermes_constants import reset_hermes_home_override, set_hermes_home_override
+from plugins.memory.honcho.client import (
+    HonchoClientConfig,
+    get_honcho_client,
+    reset_honcho_client,
+)
+
+pytestmark = pytest.mark.skipif(
+    not pytest.importorskip("honcho", reason="honcho SDK not installed"),
+    reason="honcho SDK not installed",
+)
+
+
+@pytest.fixture(autouse=True)
+def _clean_client_cache():
+    reset_honcho_client()
+    yield
+    reset_honcho_client()
+
+
+def _make_profile(tmp_path, name: str, workspace: str, api_key: str,
+                  host: str | None = None, oauth: dict | None = None):
+    home = tmp_path / name
+    home.mkdir(parents=True, exist_ok=True)
+    host = host or "hermes"
+    block: dict = {"apiKey": api_key, "workspace": workspace}
+    if oauth:
+        block["oauth"] = oauth
+    (home / "honcho.json").write_text(json.dumps({"hosts": {host: block}}))
+    return home
+
+
+class _FakeHoncho:
+    """Stands in for honcho.Honcho; records constructor kwargs."""
+
+    instances: list = []
+
+    def __init__(self, **kwargs):
+        self.kwargs = kwargs
+        _FakeHoncho.instances.append(self)
+
+
+@pytest.fixture
+def fake_honcho(monkeypatch):
+    _FakeHoncho.instances = []
+    import honcho
+
+    monkeypatch.setattr(honcho, "Honcho", _FakeHoncho)
+    return _FakeHoncho
+
+
+class TestTwoProfileIsolation:
+    def test_profiles_get_distinct_clients_and_workspaces(self, tmp_path, fake_honcho):
+        """#69123's minimal repro: override -> client -> reset -> override -> client."""
+        home_a = _make_profile(tmp_path, "profiles/a", "tenant-a", "key-a")
+        home_b = _make_profile(tmp_path, "profiles/b", "tenant-b", "key-b")
+
+        token = set_hermes_home_override(home_a)
+        try:
+            cfg_a = HonchoClientConfig.from_global_config()
+            client_a = get_honcho_client(cfg_a)
+        finally:
+            reset_hermes_home_override(token)
+
+        token = set_hermes_home_override(home_b)
+        try:
+            cfg_b = HonchoClientConfig.from_global_config()
+            client_b = get_honcho_client(cfg_b)
+        finally:
+            reset_hermes_home_override(token)
+
+        assert client_a is not client_b
+        assert client_a.kwargs["workspace_id"] == "tenant-a"
+        assert client_b.kwargs["workspace_id"] == "tenant-b"
+        assert client_a.kwargs["api_key"] == "key-a"
+        assert client_b.kwargs["api_key"] == "key-b"
+
+    def test_same_profile_reuses_client(self, tmp_path, fake_honcho):
+        home_a = _make_profile(tmp_path, "profiles/a", "tenant-a", "key-a")
+
+        token = set_hermes_home_override(home_a)
+        try:
+            cfg1 = HonchoClientConfig.from_global_config()
+            c1 = get_honcho_client(cfg1)
+            cfg2 = HonchoClientConfig.from_global_config()
+            c2 = get_honcho_client(cfg2)
+        finally:
+            reset_hermes_home_override(token)
+
+        assert c1 is c2
+        assert len(fake_honcho.instances) == 1
+
+
+class TestBackgroundThreadIsolation:
+    def test_bound_config_wins_on_bare_thread(self, tmp_path, fake_honcho):
+        """A manager's bound config must acquire ITS profile's client even
+        from a thread that cannot see the profile ContextVar — the pattern
+        of every plugin daemon thread (async writer, prefetch, sync)."""
+        home_a = _make_profile(tmp_path, "profiles/a", "tenant-a", "key-a")
+        home_b = _make_profile(tmp_path, "profiles/b", "tenant-b", "key-b")
+
+        # Default-profile client exists first (the "pinning" client).
+        token = set_hermes_home_override(home_a)
+        try:
+            cfg_a = HonchoClientConfig.from_global_config()
+            get_honcho_client(cfg_a)
+        finally:
+            reset_hermes_home_override(token)
+
+        # Profile B's config resolved inside its scope (as initialize() does).
+        token = set_hermes_home_override(home_b)
+        try:
+            cfg_b = HonchoClientConfig.from_global_config()
+        finally:
+            reset_hermes_home_override(token)
+
+        # A bare thread (empty context — no profile override visible)
+        # acquires via the bound config, as manager.honcho now does.
+        box: dict = {}
+
+        def _worker():
+            box["client"] = get_honcho_client(cfg_b)
+
+        t = threading.Thread(target=_worker)
+        t.start()
+        t.join(timeout=10)
+
+        assert box["client"].kwargs["workspace_id"] == "tenant-b"
+        assert box["client"].kwargs["api_key"] == "key-b"
+
+    def test_spawn_context_thread_sees_profile_override(self, tmp_path):
+        """spawn_context_thread must carry the caller's HERMES_HOME override."""
+        from hermes_constants import get_hermes_home
+        from plugins.memory.honcho.client import spawn_context_thread
+
+        home_b = tmp_path / "profiles" / "b"
+        home_b.mkdir(parents=True)
+        seen: dict = {}
+
+        def _probe():
+            seen["home"] = get_hermes_home()
+
+        token = set_hermes_home_override(home_b)
+        try:
+            t = spawn_context_thread(_probe, name="probe")
+            t.start()
+            t.join(timeout=10)
+        finally:
+            reset_hermes_home_override(token)
+
+        assert seen["home"] == home_b
+
+    def test_plain_thread_does_not_see_override(self, tmp_path):
+        """Control: documents WHY propagation is needed — a plain thread
+        resolves the process home, not the caller's profile override."""
+        from hermes_constants import get_hermes_home
+
+        home_b = tmp_path / "profiles" / "b"
+        home_b.mkdir(parents=True)
+        seen: dict = {}
+
+        def _probe():
+            seen["home"] = get_hermes_home()
+
+        token = set_hermes_home_override(home_b)
+        try:
+            t = threading.Thread(target=_probe)
+            t.start()
+            t.join(timeout=10)
+        finally:
+            reset_hermes_home_override(token)
+
+        assert seen["home"] != home_b
+
+
+class TestCredentialIdentity:
+    def test_account_swap_creates_new_client_and_evicts_old(self, tmp_path, fake_honcho):
+        """Switching accounts via setup (same path/host, new apiKey) must not
+        keep serving the old account's client — the collision a
+        provenance-only cache key cannot close."""
+        home = _make_profile(tmp_path, "profiles/a", "tenant-a", "key-account-1")
+
+        token = set_hermes_home_override(home)
+        try:
+            cfg1 = HonchoClientConfig.from_global_config()
+            c1 = get_honcho_client(cfg1)
+
+            # Operator re-runs setup: same file, new account credentials.
+            (home / "honcho.json").write_text(json.dumps({
+                "hosts": {"hermes": {"apiKey": "key-account-2", "workspace": "tenant-a"}},
+            }))
+            cfg2 = HonchoClientConfig.from_global_config()
+            c2 = get_honcho_client(cfg2)
+        finally:
+            reset_hermes_home_override(token)
+
+        assert c1 is not c2
+        assert c2.kwargs["api_key"] == "key-account-2"
+        # Old slot evicted: the stale client is no longer reachable via the map.
+        with client_mod._client_slots_lock:
+            cached_clients = [
+                s.peek() for s in client_mod._client_slots.values()
+            ]
+        assert c1 not in cached_clients
+
+    def test_oauth_refresh_token_is_fingerprint_basis(self, tmp_path):
+        """Fingerprint must survive access-token rotation (in-place bearer
+        swap) but change when the refresh token (re-auth) changes."""
+        home = tmp_path / "p"
+        home.mkdir()
+        oauth_block = {
+            "refreshToken": "refresh-1",
+            "tokenEndpoint": "https://auth.example/token",
+            "clientId": "cid",
+            "expiresAt": 9999999999,
+        }
+        (home / "honcho.json").write_text(json.dumps({
+            "hosts": {"hermes": {"apiKey": "access-token-1", "workspace": "w",
+                                  "oauth": oauth_block}},
+        }))
+
+        token = set_hermes_home_override(home)
+        try:
+            cfg1 = HonchoClientConfig.from_global_config()
+            fp1 = client_mod._credential_fingerprint(cfg1)
+
+            # Access token rotates in place; refresh token unchanged.
+            cfg_rotated = HonchoClientConfig.from_global_config()
+            cfg_rotated.api_key = "access-token-2"
+            fp_rotated = client_mod._credential_fingerprint(cfg_rotated)
+
+            # Re-auth: new refresh token.
+            oauth_block2 = dict(oauth_block, refreshToken="refresh-2")
+            (home / "honcho.json").write_text(json.dumps({
+                "hosts": {"hermes": {"apiKey": "access-token-3", "workspace": "w",
+                                      "oauth": oauth_block2}},
+            }))
+            cfg2 = HonchoClientConfig.from_global_config()
+            fp2 = client_mod._credential_fingerprint(cfg2)
+        finally:
+            reset_hermes_home_override(token)
+
+        assert fp1 == fp_rotated, "access-token rotation must not change identity"
+        assert fp1 != fp2, "re-auth must change identity"
+
+    def test_timeout_change_rebuilds_via_key(self, tmp_path, fake_honcho):
+        """The old singleton had an explicit timeout-staleness check; with
+        timeout in the key, a change produces a new identity + eviction."""
+        home = _make_profile(tmp_path, "profiles/a", "w", "k")
+        token = set_hermes_home_override(home)
+        try:
+            cfg1 = HonchoClientConfig.from_global_config()
+            c1 = get_honcho_client(cfg1)
+
+            raw = json.loads((home / "honcho.json").read_text())
+            raw["hosts"]["hermes"]["timeout"] = 77
+            (home / "honcho.json").write_text(json.dumps(raw))
+            cfg2 = HonchoClientConfig.from_global_config()
+            c2 = get_honcho_client(cfg2)
+        finally:
+            reset_hermes_home_override(token)
+
+        assert c1 is not c2
+        assert c2.kwargs["timeout"] == 77.0
+
+
+class TestProvenance:
+    def test_from_global_config_captures_provenance(self, tmp_path):
+        home = _make_profile(tmp_path, "profiles/a", "w", "k")
+        token = set_hermes_home_override(home)
+        try:
+            cfg = HonchoClientConfig.from_global_config()
+        finally:
+            reset_hermes_home_override(token)
+
+        assert cfg.config_path == home / "honcho.json"
+        assert cfg.hermes_home == home
+        assert cfg.bound_config_path() == home / "honcho.json"
+
+    def test_bound_path_stable_outside_scope(self, tmp_path):
+        """The captured path must not drift when read outside the profile
+        scope (the daemon-thread situation)."""
+        home = _make_profile(tmp_path, "profiles/a", "w", "k")
+        token = set_hermes_home_override(home)
+        try:
+            cfg = HonchoClientConfig.from_global_config()
+        finally:
+            reset_hermes_home_override(token)
+
+        # Now OUTSIDE the scope — bound path still points at profile a.
+        assert cfg.bound_config_path() == home / "honcho.json"