diff --git a/changelog.d/features/8347-cliproxy-reasoning-levels.md b/changelog.d/features/8347-cliproxy-reasoning-levels.md
new file mode 100644
index 0000000000..b75cb72687
--- /dev/null
+++ b/changelog.d/features/8347-cliproxy-reasoning-levels.md
@@ -0,0 +1 @@
+- feat(providers): map upstream reasoning-level metadata in openai-compatible discovery (#8347)
diff --git a/src/app/api/providers/[id]/models/discoveryClientVersion.ts b/src/app/api/providers/[id]/models/discoveryClientVersion.ts
new file mode 100644
index 0000000000..b359e59999
--- /dev/null
+++ b/src/app/api/providers/[id]/models/discoveryClientVersion.ts
@@ -0,0 +1,57 @@
+// #8347: CLIProxyAPI-style upstreams gate a richer catalog behind a `client_version` query
+// param on the model-list request (mirroring `discovery/codex.ts::buildCodexModelsUrl`).
+// This is a per-connection, default-OFF opt-in — appending an unexpected query param to
+// every generic OpenAI-compatible upstream's model-list call is the stated regression
+// vector, so this MUST default to false and MUST never be applied to inference URLs.
+
+type JsonRecord = Record<string, unknown>;
+
+function asRecord(value: unknown): JsonRecord {
+  return value && typeof value === "object" && !Array.isArray(value) ? (value as JsonRecord) : {};
+}
+
+export type DiscoveryClientVersionOptions = {
+  discoveryClientVersionEnabled?: boolean;
+  discoveryClientVersion?: string;
+};
+
+/**
+ * Reads the opt-in flag + optional version string off a connection's
+ * `providerSpecificData`. Default is OFF: absent, falsy, or malformed data never enables
+ * the query param.
+ */
+export function getDiscoveryClientVersionOptions(
+  providerSpecificData: unknown
+): DiscoveryClientVersionOptions {
+  const record = asRecord(providerSpecificData);
+  const enabled = record.discoveryClientVersionEnabled === true;
+  const version =
+    typeof record.discoveryClientVersion === "string" && record.discoveryClientVersion.trim()
+      ? record.discoveryClientVersion.trim()
+      : undefined;
+  return { discoveryClientVersionEnabled: enabled, discoveryClientVersion: version };
+}
+
+/**
+ * Appends `client_version` to a model-LIST URL only, and only when the connection has
+ * explicitly opted in. Never call this for an inference/chat-completions URL. Returns the
+ * URL unchanged (byte-identical) when the opt-in is absent or off, so unrelated generic
+ * OpenAI-compatible upstreams see no behavior change.
+ */
+export function buildProviderModelsUrl(
+  modelsUrl: string,
+  options: DiscoveryClientVersionOptions | undefined
+): string {
+  if (!options?.discoveryClientVersionEnabled || !options.discoveryClientVersion) {
+    return modelsUrl;
+  }
+  try {
+    const url = new URL(modelsUrl);
+    url.searchParams.set("client_version", options.discoveryClientVersion);
+    return url.toString();
+  } catch {
+    // Malformed base URL — fall back to the untouched string rather than throwing;
+    // the caller's own fetch will surface the real error.
+    return modelsUrl;
+  }
+}
diff --git a/src/app/api/providers/[id]/models/route.ts b/src/app/api/providers/[id]/models/route.ts
index b24c4b7cf5..c7d74a1f9d 100755
--- a/src/app/api/providers/[id]/models/route.ts
+++ b/src/app/api/providers/[id]/models/route.ts
@@ -83,6 +83,10 @@ import {
   isAutoFetchModelsEnabled,
   persistDiscoveredModels,
 } from "@/lib/providerModels/modelDiscovery";
+import {
+  buildProviderModelsUrl,
+  getDiscoveryClientVersionOptions,
+} from "./discoveryClientVersion";
 import {
   parseGeminiModelsList,
   type GeminiDiscoveryModel,
@@ -802,8 +806,16 @@ export async function GET(
         `${baseUrl.replace(/\/$/, "")}/models`, // Original fallback
       ];
 
+      // #8347: opt-in `client_version` query param on the model-LIST request only (never on
+      // any inference URL, and never on this path by default) — see discoveryClientVersion.ts.
+      const discoveryClientVersionOptions = getDiscoveryClientVersionOptions(
+        connection.providerSpecificData
+      );
+
       // Remove duplicates
-      const uniqueEndpoints = [...new Set(endpoints)];
+      const uniqueEndpoints = [...new Set(endpoints)].map((endpoint) =>
+        buildProviderModelsUrl(endpoint, discoveryClientVersionOptions)
+      );
       let models = null;
       let lastErrorStatus = null;
       const token = apiKey || accessToken;
diff --git a/src/lib/providerModels/modelDiscovery.ts b/src/lib/providerModels/modelDiscovery.ts
index 7e7d91927a..b463f7fac3 100644
--- a/src/lib/providerModels/modelDiscovery.ts
+++ b/src/lib/providerModels/modelDiscovery.ts
@@ -71,6 +71,18 @@ const reasoningSupportedEffortsSchema = z
   .nullable()
   .optional();
 
+// #8347: CLIProxyAPI-style upstreams expose reasoning tiers as a top-level
+// `supported_reasoning_levels` array, or nested under `thinking.levels`. Both accept
+// entries that are either plain strings or `{ effort: string }` objects (the report shows
+// the object form; `discovery/codex.ts:140` reads the same `supported_reasoning_levels`
+// key as a bare existence check). Validate with Zod (Hard Rule #7): a malformed ENTRY is
+// dropped individually rather than failing the whole array/record.
+const effortEntrySchema = z.union([z.string(), z.object({ effort: z.string() })]);
+const effortListSchema = z.array(z.unknown());
+
+const supportedReasoningLevelsSchema = z.object({ supported_reasoning_levels: z.unknown() });
+const thinkingLevelsSchema = z.object({ thinking: z.object({ levels: z.unknown() }).partial() });
+
 // Maps common upstream synonyms onto OmniRoute's canonical effort vocabulary
 // (`src/shared/reasoning/effortStandardization.ts`). Values already in
 // `CANONICAL_EFFORT_VALUES`, and any unrecognized provider-native tier (e.g.
@@ -82,6 +94,32 @@ function normalizeSupportedEffort(effort: string): string {
   return EFFORT_SYNONYMS[effort.toLowerCase()] || effort;
 }
 
+/**
+ * #8347: shared parser for the two new upstream shapes (`supported_reasoning_levels`,
+ * `thinking.levels`). Accepts a list whose entries are either plain strings or
+ * `{ effort: string }` objects, drops malformed entries individually (never throws), and
+ * normalizes survivors onto the canonical vocabulary. Returns `undefined` when nothing
+ * usable remains, mirroring `detectSupportedThinkingEfforts`'s existing contract.
+ */
+function parseEffortList(rawList: unknown): string[] | undefined {
+  const listParsed = effortListSchema.safeParse(rawList);
+  if (!listParsed.success) return undefined;
+
+  const efforts = Array.from(
+    new Set(
+      listParsed.data
+        .map((entry) => {
+          const entryParsed = effortEntrySchema.safeParse(entry);
+          if (!entryParsed.success) return null;
+          const raw = typeof entryParsed.data === "string" ? entryParsed.data : entryParsed.data.effort;
+          return raw.length > 0 ? normalizeSupportedEffort(raw) : null;
+        })
+        .filter((effort): effort is string => effort !== null)
+    )
+  );
+  return efforts.length > 0 ? efforts : undefined;
+}
+
 /**
  * #7694: read the nested `record.reasoning.supported_efforts` shape and normalize each
  * tier onto the canonical vocabulary. Returns `undefined` (never throws) when the field
@@ -91,19 +129,36 @@ function normalizeSupportedEffort(effort: string): string {
  */
 export function detectSupportedThinkingEfforts(record: JsonRecord): string[] | undefined {
   const parsed = reasoningSupportedEffortsSchema.safeParse(record.reasoning);
-  if (!parsed.success || !parsed.data) return undefined;
+  if (parsed.success && parsed.data) {
+    const rawEfforts = parsed.data.supported_efforts;
+    if (Array.isArray(rawEfforts)) {
+      const efforts = Array.from(
+        new Set(
+          rawEfforts
+            .filter((effort): effort is string => typeof effort === "string" && effort.length > 0)
+            .map(normalizeSupportedEffort)
+        )
+      );
+      if (efforts.length > 0) return efforts;
+    }
+  }
 
-  const rawEfforts = parsed.data.supported_efforts;
-  if (!Array.isArray(rawEfforts)) return undefined;
+  // #8347: fall back to `supported_reasoning_levels`, then `thinking.levels` — in that
+  // order, per the regression guard for #7694 (the flat field and `reasoning.supported_efforts`
+  // both take precedence over these two and are handled above / by the caller).
+  const levelsParsed = supportedReasoningLevelsSchema.safeParse(record);
+  if (levelsParsed.success) {
+    const fromLevels = parseEffortList(levelsParsed.data.supported_reasoning_levels);
+    if (fromLevels) return fromLevels;
+  }
 
-  const efforts = Array.from(
-    new Set(
-      rawEfforts
-        .filter((effort): effort is string => typeof effort === "string" && effort.length > 0)
-        .map(normalizeSupportedEffort)
-    )
-  );
-  return efforts.length > 0 ? efforts : undefined;
+  const thinkingParsed = thinkingLevelsSchema.safeParse(record);
+  if (thinkingParsed.success) {
+    const fromThinking = parseEffortList(thinkingParsed.data.thinking?.levels);
+    if (fromThinking) return fromThinking;
+  }
+
+  return undefined;
 }
 
 export function isAutoFetchModelsEnabled(providerSpecificData: unknown): boolean {
@@ -177,10 +232,11 @@ export function normalizeDiscoveredModels(models: unknown): SyncedAvailableModel
         : {}),
       ...(supportedEndpoints && supportedEndpoints.length > 0 ? { supportedEndpoints } : {}),
       ...(() => {
-        // #7694: the flat field (OmniRoute's own import format) wins verbatim when
-        // present, unchanged from its current pass-through behavior; only fall back to
-        // the nested `reasoning.supported_efforts` shape (normalized onto the canonical
-        // vocabulary) when the flat field is absent.
+        // #7694/#8347: the flat field (OmniRoute's own import format) wins verbatim when
+        // present, unchanged from its current pass-through behavior. Otherwise
+        // `detectSupportedThinkingEfforts` falls back in order: `reasoning.supported_efforts`
+        // → `supported_reasoning_levels` → `thinking.levels` (all normalized onto the
+        // canonical vocabulary) — never disturbing the flat field's precedence.
         if (Array.isArray(record.supportedThinkingEfforts)) {
           return {
             supportedThinkingEfforts: record.supportedThinkingEfforts.filter(
diff --git a/tests/unit/model-discovery-reasoning-levels.test.ts b/tests/unit/model-discovery-reasoning-levels.test.ts
new file mode 100644
index 0000000000..1e0bd34518
--- /dev/null
+++ b/tests/unit/model-discovery-reasoning-levels.test.ts
@@ -0,0 +1,129 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import {
+  detectSupportedThinkingEfforts,
+  normalizeDiscoveredModels,
+} from "@/lib/providerModels/modelDiscovery";
+import { buildProviderModelsUrl } from "@/app/api/providers/[id]/models/discoveryClientVersion";
+
+// #8347: generic openai-compatible / custom-node discovery had no metadata-mapping layer
+// for `supported_reasoning_levels` (CLIProxyAPI-style upstreams) or `thinking.levels`. This
+// suite proves the two new shapes are parsed onto the existing `supportedThinkingEfforts`
+// pipeline, that the #7694 precedence order is preserved, and that the `client_version`
+// opt-in touches the model-list URL only — never inference URLs — and defaults off.
+
+test("supported_reasoning_levels as {effort} objects is parsed into supportedThinkingEfforts", () => {
+  const record = {
+    id: "model-a",
+    supported_reasoning_levels: [{ effort: "low" }, { effort: "high" }],
+  };
+  assert.deepEqual(detectSupportedThinkingEfforts(record), ["low", "high"]);
+});
+
+test("supported_reasoning_levels as plain strings is parsed into supportedThinkingEfforts", () => {
+  const record = {
+    id: "model-b",
+    supported_reasoning_levels: ["low", "medium"],
+  };
+  assert.deepEqual(detectSupportedThinkingEfforts(record), ["low", "medium"]);
+});
+
+test("thinking.levels is parsed into supportedThinkingEfforts", () => {
+  const record = {
+    id: "model-c",
+    thinking: { levels: ["medium", "high"] },
+  };
+  assert.deepEqual(detectSupportedThinkingEfforts(record), ["medium", "high"]);
+});
+
+test("duplicates are deduped, max canonicalizes to xhigh, unknown native tier retained", () => {
+  const record = {
+    id: "model-d",
+    supported_reasoning_levels: [{ effort: "max" }, { effort: "max" }, { effort: "ultra" }],
+  };
+  assert.deepEqual(detectSupportedThinkingEfforts(record), ["xhigh", "ultra"]);
+});
+
+test("a malformed entry inside an otherwise-valid array is dropped, the rest survive, no throw", () => {
+  const record = {
+    id: "model-e",
+    supported_reasoning_levels: [{ effort: "low" }, { effort: 42 }, null, "high", 7],
+  };
+  assert.doesNotThrow(() => detectSupportedThinkingEfforts(record));
+  assert.deepEqual(detectSupportedThinkingEfforts(record), ["low", "high"]);
+});
+
+test("a fully malformed shape degrades to undefined instead of throwing", () => {
+  const record = { id: "model-f", supported_reasoning_levels: "not-an-array" };
+  assert.doesNotThrow(() => detectSupportedThinkingEfforts(record));
+  assert.equal(detectSupportedThinkingEfforts(record), undefined);
+});
+
+test("precedence: flat supportedThinkingEfforts wins over reasoning.supported_efforts and both new shapes (#7694 regression guard)", () => {
+  const models = normalizeDiscoveredModels([
+    {
+      id: "model-g",
+      supportedThinkingEfforts: ["none"],
+      reasoning: { supported_efforts: ["low"] },
+      supported_reasoning_levels: ["medium"],
+      thinking: { levels: ["high"] },
+    },
+  ]);
+  assert.deepEqual(models[0].supportedThinkingEfforts, ["none"]);
+});
+
+test("precedence: reasoning.supported_efforts wins over supported_reasoning_levels and thinking.levels", () => {
+  const models = normalizeDiscoveredModels([
+    {
+      id: "model-h",
+      reasoning: { supported_efforts: ["low"] },
+      supported_reasoning_levels: ["medium"],
+      thinking: { levels: ["high"] },
+    },
+  ]);
+  assert.deepEqual(models[0].supportedThinkingEfforts, ["low"]);
+});
+
+test("precedence: supported_reasoning_levels wins over thinking.levels when both present", () => {
+  const models = normalizeDiscoveredModels([
+    {
+      id: "model-i",
+      supported_reasoning_levels: ["medium"],
+      thinking: { levels: ["high"] },
+    },
+  ]);
+  assert.deepEqual(models[0].supportedThinkingEfforts, ["medium"]);
+});
+
+test("thinking.levels alone still populates supportedThinkingEfforts via normalizeDiscoveredModels", () => {
+  const models = normalizeDiscoveredModels([
+    {
+      id: "model-j",
+      thinking: { levels: ["high"] },
+    },
+  ]);
+  assert.deepEqual(models[0].supportedThinkingEfforts, ["high"]);
+});
+
+test("client_version is absent from the model-list URL by default", () => {
+  const url = buildProviderModelsUrl("https://example.com/v1/models", undefined);
+  assert.equal(url, "https://example.com/v1/models");
+  assert.ok(!url.includes("client_version"));
+});
+
+test("client_version is present on the model-list URL only when the connection opts in", () => {
+  const url = buildProviderModelsUrl("https://example.com/v1/models", {
+    discoveryClientVersionEnabled: true,
+    discoveryClientVersion: "1.2.3",
+  });
+  const parsed = new URL(url);
+  assert.equal(parsed.searchParams.get("client_version"), "1.2.3");
+});
+
+test("client_version opt-in without an explicit version still defaults off (no gate silently mutates every request)", () => {
+  const url = buildProviderModelsUrl("https://example.com/v1/models", {
+    discoveryClientVersionEnabled: false,
+    discoveryClientVersion: "1.2.3",
+  });
+  assert.ok(!url.includes("client_version"));
+});