diff --git a/custom_components/houseplan/websocket_api.py b/custom_components/houseplan/websocket_api.py
index 5242b08..28eaa56 100755
--- a/custom_components/houseplan/websocket_api.py
+++ b/custom_components/houseplan/websocket_api.py
@@ -477,12 +477,11 @@ async def ws_config_get(hass: HomeAssistant, connection, msg: dict[str, Any]) ->
 
 
 
-def _missing_internal_plans(plans_dir: Path, config: dict[str, Any]) -> set[str]:
-    """Plan files a configuration names that are not on disk.
+def _internal_plan_names(config: dict[str, Any]) -> set[str]:
+    """Plan file names a configuration names through OUR urls.
 
-    Only OUR urls are checked — `/api/houseplan/content/plans/_/<name>` and the
-    legacy static path. Anything else belongs to the user and may point wherever
-    they like.
+    Only `/api/houseplan/content/plans/_/<name>` and the legacy static path
+    count. Anything else belongs to the user and may point wherever they like.
     """
     out: set[str] = set()
     for space in (config or {}).get("spaces") or []:
@@ -492,11 +491,32 @@ def _missing_internal_plans(plans_dir: Path, config: dict[str, Any]) -> set[str]
         if not (url.startswith(CONTENT_URL + "/plans/") or url.startswith(PLANS_URL + "/")):
             continue
         name = plan_basename(url)
-        if name and not (plans_dir / name).is_file():
+        if name:
             out.add(name)
     return out
 
 
+def _missing_internal_plans(
+    plans_dir: Path, config: dict[str, Any], previous: dict[str, Any] | None = None
+) -> set[str]:
+    """Newly named plan files that are not on disk.
+
+    Guards the pick-then-save window: another client may delete a plan between
+    the moment this one chose it and the moment it saves, which would otherwise
+    store a url with nothing behind it (HP-1470-02).
+
+    A name the stored configuration already carries is deliberately let through.
+    It is already broken — repairs says so — and refusing the write would lock
+    the owner out of every other edit, including the one that detaches it.
+    """
+    known = _internal_plan_names(previous or {})
+    return {
+        name
+        for name in _internal_plan_names(config)
+        if name not in known and not (plans_dir / name).is_file()
+    }
+
+
 @websocket_api.websocket_command(
     {
         vol.Required("type"): "houseplan/config/set",
@@ -552,7 +572,10 @@ async def ws_config_set(hass: HomeAssistant, connection, msg: dict[str, Any]) ->
         # nothing about whether the file survived (HP-1470-02). External and
         # legacy urls are not ours to check and are left alone.
         missing = await hass.async_add_executor_job(
-            _missing_internal_plans, Path(hass.config.path(PLANS_DIR)), msg["config"]
+            _missing_internal_plans,
+            Path(hass.config.path(PLANS_DIR)),
+            msg["config"],
+            data.get("config"),
         )
         if missing:
             connection.send_error(
diff --git a/tests_backend/test_ha_websocket.py b/tests_backend/test_ha_websocket.py
index 4a63b7c..967aa99 100644
--- a/tests_backend/test_ha_websocket.py
+++ b/tests_backend/test_ha_websocket.py
@@ -784,8 +784,22 @@ async def test_repair_issue_goes_when_its_space_does(
     client = await hass_ws_client(hass)
     registry = ir.async_get(hass)
 
-    gone = "/api/houseplan/content/plans/_/nosuchfile.png"
-    rev = (await _save(client, await _cfg([{"id": "r7", "plan_url": gone}]), 0))["result"]["rev"]
+    # A reference can only go bad AFTER it is stored — config/set refuses a new
+    # one that is already broken (HP-1470-02). So: attach a real plan, then let
+    # the file disappear the way it does in life, from outside Home Assistant.
+    import os
+
+    from custom_components.houseplan.const import PLANS_DIR
+
+    url, name = await _upload(client, "r7", b"PLAN")
+    rev = (await _save(client, await _cfg([{"id": "r7", "plan_url": url}]), 0))["result"]["rev"]
+    await hass.async_block_till_done()
+    assert registry.async_get_issue(HP_DOMAIN, "broken_plan_r7") is None, "the file is there"
+
+    await hass.async_add_executor_job(
+        os.remove, os.path.join(hass.config.path(PLANS_DIR), name)
+    )
+    rev = (await _save(client, await _cfg([{"id": "r7", "plan_url": url}]), rev))["result"]["rev"]
     await hass.async_block_till_done()
     assert registry.async_get_issue(HP_DOMAIN, "broken_plan_r7") is not None
 
@@ -940,6 +954,9 @@ async def test_startup_sweep_collects_what_no_commit_will(
     await _setup(hass)
     client = await hass_ws_client(hass)
     files, _plans, p = _paths(hass)
+    # the plan it names has to exist: config/set refuses a NEW broken
+    # reference (HP-1470-02). The orphans still arrive after the save.
+    await _seed_aged(hass, [p["kept_plan"]])
     assert (await _save(client, await _referenced_config(), 0))["success"]
 
     await _seed_aged(hass, list(p.values()))
@@ -967,6 +984,9 @@ async def test_periodic_sweep_collects_too(
     await _setup(hass)
     client = await hass_ws_client(hass)
     _files, _plans, p = _paths(hass)
+    # the plan it names has to exist: config/set refuses a NEW broken
+    # reference (HP-1470-02). The orphans still arrive after the save.
+    await _seed_aged(hass, [p["kept_plan"]])
     assert (await _save(client, await _referenced_config(), 0))["success"]
 
     await _seed_aged(hass, list(p.values()))
@@ -994,6 +1014,9 @@ async def test_sweep_and_a_config_write_do_not_race(
     await _setup(hass)
     client = await hass_ws_client(hass)
     _files, plans, p = _paths(hass)
+    # the plan it names has to exist: config/set refuses a NEW broken
+    # reference (HP-1470-02). The orphans still arrive after the save.
+    await _seed_aged(hass, [p["kept_plan"]])
     rev = (await _save(client, await _referenced_config(), 0))["result"]["rev"]
 
     # an aged, currently unreferenced plan that the commit below adopts
@@ -1192,9 +1215,19 @@ async def test_uploads_are_bounded_by_a_store_quota(
     """HP-1470-01: nothing is deleted for being old, so growth stops at the door."""
     from custom_components.houseplan import websocket_api as wsapi
 
+    from pathlib import Path
+
+    from custom_components.houseplan.const import PLANS_DIR
+    from custom_components.houseplan.plans import dir_usage
+
     await _setup(hass)
     client = await hass_ws_client(hass)
-    monkeypatch.setattr(wsapi, "MAX_PLANS_FILES", 2)
+    # every test in this module shares one config directory, so the plans folder
+    # is not empty here — budget two more from whatever is already stored
+    stored, _b = await hass.async_add_executor_job(
+        lambda: dir_usage(Path(hass.config.path(PLANS_DIR)))[::-1]
+    )
+    monkeypatch.setattr(wsapi, "MAX_PLANS_FILES", stored + 2)
 
     await _upload(client, "q1", b"one")
     await _upload(client, "q1", b"two")