Merge remote-tracking branch 'origin/master' into gitea/feature/end

Resolved conflicts taking origin/master (v0.5.55) as canonical, with local
features re-applied:
- runtime log level (LOG_LEVEL env + dashboard Settings → Logging, applied
  immediately and persisted across restarts)
- free/noAuth provider enable/disable toggle via providerStrategies.enabled
- parallel model testing (Test All Models / Test Selected Keys)

tests/unit/responses-prompt-cache-key-3216.test.js

@@ -0,0 +1,44 @@
+import { describe, expect, it } from "vitest";
+
+const { openaiToOpenAIResponsesRequest, openaiResponsesToOpenAIRequest } =
+  await import("../../open-sse/translator/request/openai-responses.js");
+
+const CHAT_BODY = (extra = {}) => ({
+  model: "example-model",
+  messages: [{ role: "user", content: "hello" }],
+  ...extra,
+});
+
+describe("#3216 prompt_cache_key across the chat/responses translation", () => {
+  it("preserves an explicit key when converting chat → responses", () => {
+    const out = openaiToOpenAIResponsesRequest(
+      "example-model",
+      CHAT_BODY({ prompt_cache_key: "stable-cache-key" }),
+      true,
+      {},
+    );
+
+    expect(out.prompt_cache_key).toBe("stable-cache-key");
+  });
+
+  it("does not invent a key when the client sent none", () => {
+    const out = openaiToOpenAIResponsesRequest("example-model", CHAT_BODY(), true, {});
+
+    expect(out.prompt_cache_key).toBeUndefined();
+  });
+
+  it("still drops the key on the responses → chat direction", () => {
+    const out = openaiResponsesToOpenAIRequest(
+      "example-model",
+      {
+        model: "example-model",
+        input: [{ role: "user", content: [{ type: "input_text", text: "hello" }] }],
+        prompt_cache_key: "stable-cache-key",
+      },
+      true,
+      {},
+    );
+
+    expect(out.prompt_cache_key).toBeUndefined();
+  });
+});