1 files changed, 35 insertions, 5 deletions
diff --git a/docs/superpowers/plans/2026-08-09-external-providers.md b/docs/superpowers/plans/2026-08-09-external-providers.md
index a17c1d9..0c8fc19 100644
--- a/docs/superpowers/plans/2026-08-09-external-providers.md
+++ b/docs/superpowers/plans/2026-08-09-external-providers.md
@@ -137,6 +137,26 @@ def test_provider_parsing():
     # Unset numbers stay None so "unknown" is distinguishable from zero.
     assert parsed["local"].ctx_size is None
     assert parsed["local"].price_in is None
+
+    # A [providers.local] that omits base_url inherits the bare one rather
+    # than shadowing the local provider out of existence.
+    partial = providers.parse(
+        {
+            "base_url": "http://localhost:8181",
+            "providers": {"local": {"api_key": "env:SOME_VAR"}},
+        }
+    )
+    assert set(partial) == {"local"}
+    assert partial["local"].base_url == "http://localhost:8181"
+    # The explicit entry's own fields survive the merge.
+    assert partial["local"].api_key == "env:SOME_VAR"
+
+    # A filter given as a bare string is one needle, not four.
+    stringy = providers.parse(
+        {"providers": {"p": {"base_url": "http://x.example.org",
+                             "filter": "qwen"}}}
+    )
+    assert stringy["p"].filter == ["qwen"]
     print("ok  provider config parsing")
 ```
 
@@ -210,11 +230,15 @@ def parse(values: dict) -> dict[str, Provider]:
     """
     table = dict(values.get("providers") or {})
 
-    # An old config has only a bare base_url. Synthesize the local provider
-    # from it so nothing needs migrating, but never override an explicit one.
+    # An old config has only a bare base_url. Fill it in as the local
+    # provider's URL so nothing needs migrating, but never override an
+    # explicit one. The test is the URL rather than the key: a
+    # [providers.local] that only sets an api_key is adding detail to the
+    # provider the user already has, not replacing it, and treating it as a
+    # replacement would silently delete local entirely.
     bare = values.get("base_url")
-    if bare and LOCAL not in table:
-        table[LOCAL] = {"base_url": bare}
+    if bare and not (table.get(LOCAL) or {}).get("base_url"):
+        table[LOCAL] = {**(table.get(LOCAL) or {}), "base_url": bare}
 
     out: dict[str, Provider] = {}
     for name, entry in table.items():
@@ -224,12 +248,18 @@ def parse(values: dict) -> dict[str, Provider]:
             # ponytail: a provider with no URL is misconfigured, not a
             # partial one. Skipping beats inventing a default endpoint.
             continue
+        # filter = "qwen" is an easy TOML slip for filter = ["qwen"], and
+        # iterating the string would turn it into four single-character
+        # needles that match nearly every model id.
+        needles = entry.get("filter") or []
+        if isinstance(needles, str):
+            needles = [needles]
         vision = entry.get("vision")
         out[str(name)] = Provider(
             name=str(name),
             base_url=base_url,
             api_key=str(entry.get("api_key") or ""),
-            filter=[str(f) for f in (entry.get("filter") or [])],
+            filter=[str(f) for f in needles],
             ctx_size=_number(entry.get("ctx_size"), int),
             vision=None if vision is None else bool(vision),
             price_in=_number(entry.get("price_in"), float),