chore: make system more stable with invalid json responses from AI

CODESMELL.md

@@ -99,11 +99,9 @@ _None._ All modules previously on the queue have been split; refresh the queue i
 
 ## 9. `Jason.decode!/1` on External HTTP Responses
 
-**Status:** open.
+**Status:** ✅ done (2026-05-01). The 2 scoped HTTP response decodes in `BDS.AI.OpenAICompatibleRuntime` now use `Jason.decode/1` and return `{:error, %{kind: :invalid_json_response, reason: reason}}` for malformed model-list or chat-completion response bodies. The error shape propagates through endpoint model listing, chat, and one-shot orchestration via the existing `with` chains. Remaining `Jason.decode!/1` sites in `BDS.AI.Catalog` decode model-catalog HTTP/cache payloads or trusted on-disk JSON and are out of scope for this section.
 
-**Scope:** only the 2 sites in `BDS.AI` / `BDS.AI.OpenAICompatibleRuntime` that decode HTTP response bodies. The remaining 12 `Jason.decode!/1` sites decode our own on-disk files (metadata, embeddings index, generation hashes) and are not in scope.
-
-**Plan:** switch to `Jason.decode/1` and propagate `{:error, reason}` from the runtime through to the chat / one-shot orchestration layer in `BDS.AI.Chat` and `BDS.AI.OneShot`.
+**Rule:** OpenAI-compatible runtime HTTP responses must not be decoded with bang functions; malformed provider JSON is a recoverable runtime error.
 
 ---
 
@@ -161,6 +159,10 @@ Most tests share the SQLite repo and named GenServers (`BDS.Tasks`, `BDS.Search`
 
 ## Changelog
 
+### 2026-05-01
+
+- **`Jason.decode!/1` on external HTTP responses**: replaced the 2 scoped OpenAI-compatible runtime response decodes with `Jason.decode/1` and tagged `{:error, %{kind: :invalid_json_response, reason: reason}}` propagation for malformed `/models` and `/chat/completions` bodies. Added regressions covering endpoint model listing through a fake HTTP client and generation through a local Bandit server. Section 9 is closed.
+
 ### 2026-05-10
 
 - **Duplicate helpers across contexts**: added `BDS.MapUtils` (`attr/2`, `maybe_put/3`, `blank_to_nil/1`) and expanded `BDS.ProgressReporter` (`callback/1`, `scaled/3`, `report_count_started/4`, `report_count_progress/5`, `report_rebuild_started/3`, `report_rebuild_progress/4`, `report_phase/3`). Replaced copy-pasted helpers in posts, post translations, post rebuild, media file ops, search, generation progress, maintenance progress, embeddings/index progress, publishing, MCP util, scripts, and templates. Domain-specific modules now express their wording/ranges as options to the shared reporter, preserving existing user-facing progress messages while sharing one implementation. Added focused tests for both shared modules. Section 6 is closed.

lib/bds/ai/openai_compatible_runtime.ex

@@ -47,23 +47,24 @@ defmodule BDS.AI.OpenAICompatibleRuntime do
   end
 
   defp normalize_response(body) do
-    payload = Jason.decode!(body)
-    message = get_in(payload, ["choices", Access.at(0), "message"]) || %{}
-    content = normalize_content(message["content"])
-    tool_calls = normalize_tool_calls(message["tool_calls"] || [])
-    usage = normalize_usage(payload["usage"] || %{})
+    with {:ok, payload} <- decode_json_body(body) do
+      message = get_in(payload, ["choices", Access.at(0), "message"]) || %{}
+      content = normalize_content(message["content"])
+      tool_calls = normalize_tool_calls(message["tool_calls"] || [])
+      usage = normalize_usage(payload["usage"] || %{})
 
-    json =
-      case content do
-        nil -> nil
-        value when is_binary(value) ->
-          case Jason.decode(value) do
-            {:ok, decoded} when is_map(decoded) -> decoded
-            _other -> nil
-          end
-      end
+      json =
+        case content do
+          nil -> nil
+          value when is_binary(value) ->
+            case Jason.decode(value) do
+              {:ok, decoded} when is_map(decoded) -> decoded
+              _other -> nil
+            end
+        end
 
-    {:ok, %{content: content, json: json, tool_calls: tool_calls, usage: usage}}
+      {:ok, %{content: content, json: json, tool_calls: tool_calls, usage: usage}}
+    end
   end
 
   defp completions_url(url) do
@@ -84,24 +85,31 @@ defmodule BDS.AI.OpenAICompatibleRuntime do
   end
 
   defp normalize_models_response(body) do
-    payload = Jason.decode!(body)
+    with {:ok, payload} <- decode_json_body(body) do
+      models =
+        payload
+        |> Map.get("data", [])
+        |> Enum.map(fn entry ->
+          id = entry["id"] || entry[:id]
 
-    models =
-      payload
-      |> Map.get("data", [])
-      |> Enum.map(fn entry ->
-        id = entry["id"] || entry[:id]
+          %{
+            id: id,
+            label: id
+          }
+        end)
+        |> Enum.reject(&is_nil(&1.id))
+        |> Enum.uniq_by(& &1.id)
+        |> Enum.sort_by(&String.downcase(&1.id))
 
-        %{
-          id: id,
-          label: id
-        }
-      end)
-      |> Enum.reject(&is_nil(&1.id))
-      |> Enum.uniq_by(& &1.id)
-      |> Enum.sort_by(&String.downcase(&1.id))
+      {:ok, models}
+    end
+  end
 
-    {:ok, models}
+  defp decode_json_body(body) do
+    case Jason.decode(body) do
+      {:ok, payload} -> {:ok, payload}
+      {:error, reason} -> {:error, %{kind: :invalid_json_response, reason: reason}}
+    end
   end
 
   defp maybe_put_auth(headers, nil), do: headers

test/bds/ai_test.exs

@@ -88,6 +88,25 @@ defmodule BDS.AITest do
     def get(_url, _headers), do: {:error, :not_found}
   end
 
+  defmodule BadJsonEndpointHttpClient do
+    def get("https://api.example.test/v1/models", _headers) do
+      {:ok, %{status: 200, headers: %{}, body: "not json"}}
+    end
+  end
+
+  defmodule BadJsonCompletionServer do
+    use Plug.Router
+
+    plug(:match)
+    plug(:dispatch)
+
+    post "/v1/chat/completions" do
+      conn
+      |> Plug.Conn.put_resp_content_type("application/json")
+      |> Plug.Conn.send_resp(200, "not json")
+    end
+  end
+
   defmodule FakeRuntime do
     def generate(endpoint, request, opts) do
       test_pid = Keyword.fetch!(opts, :test_pid)
@@ -256,6 +275,32 @@ defmodule BDS.AITest do
     assert [%{id: "gpt-4.1", label: "gpt-4.1"}, %{id: "gpt-4.1-mini", label: "gpt-4.1-mini"}] = models
   end
 
+  test "list_endpoint_models returns an error for malformed endpoint JSON" do
+    assert {:error, %{kind: :invalid_json_response, reason: %Jason.DecodeError{}}} =
+             BDS.AI.list_endpoint_models(%{url: "https://api.example.test/v1", api_key: "online-secret"},
+               http_client: BadJsonEndpointHttpClient
+             )
+  end
+
+  test "openai-compatible generation returns an error for malformed completion JSON" do
+    server =
+      start_supervised!({Bandit, plug: BadJsonCompletionServer, port: 0, startup_log: false})
+
+    {:ok, {_address, port}} = ThousandIsland.listener_info(server)
+
+    assert {:error, %{kind: :invalid_json_response, reason: %Jason.DecodeError{}}} =
+             BDS.AI.OpenAICompatibleRuntime.generate(
+               %{url: "http://127.0.0.1:#{port}/v1", api_key: nil},
+               %{
+                 model: "gpt-test",
+                 messages: [%{"role" => "user", "content" => "Hello"}],
+                 max_output_tokens: 128,
+                 tools: []
+               },
+               []
+             )
+  end
+
   test "airplane mode routes title tasks to airplane endpoint and offline title model" do
     assert {:ok, _endpoint} =
              BDS.AI.put_endpoint(:online, %{