diff --git a/CHANGELOG.md b/CHANGELOG.md
index d950be6f84..0df8e616bb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@
 ### 🐛 Fixed
 
 - **fix(intelligence): run pricing + models.dev sync from the live startup path** — like the Arena ELO sync (v3.8.24), the external **pricing sync** (`PRICING_SYNC_ENABLED`) and the **models.dev capability sync** (Settings → AI toggle) were only initialized from `server-init.ts`, which the Next standalone runtime never executes — and models.dev had no caller at all. Their toggles were inert in production. Both are now initialized from `instrumentation-node.ts` (self-gated, opt-in preserved, non-blocking, never fatal). (thanks @diegosouzapw)
+- **fix(sse): retry once on an early stream close (`STREAM_EARLY_EOF`) for single-model requests** — flaky OpenAI-compatible upstreams (e.g. NVIDIA NIM with minimax-m3 / qwen3.5 / glm-5.1) intermittently send HTTP 200 then close the SSE with zero useful frames, surfacing as a 502 "Stream ended before producing useful content". Only Antigravity got an early-close retry; every other provider returned the 502 immediately on the non-combo single-model path. A bounded one-retry (early-close only — not readiness-timeout — and without marking the account unavailable) now generalizes it. (The separate qwen-web validation SSRF part of the same report was already fixed in v3.8.24, [#3767](https://github.com/diegosouzapw/OmniRoute/pull/3767).) ([#3758](https://github.com/diegosouzapw/OmniRoute/issues/3758) — thanks @Svatosalav)
 - **fix(models): preserve eye-hidden models across auto-sync / import** — hiding models via the visibility (eye) toggle to keep only a combo's models was undone on every model import or auto-sync, which re-showed all of them. The sync re-import treated "hidden" identically to "deleted" and dropped both; a distinct `isDeleted` marker now separates the trash/delete path (still dropped on re-import, #3199) from the eye toggle (preserved as listed-but-hidden), and eye-hidden models are no longer re-aliased into the routable catalog on sync. ([#3782](https://github.com/diegosouzapw/OmniRoute/issues/3782) — thanks @xenstar)
 - **fix(providers): correct the lmarena cookie hint (`session` → `arena-auth-prod-v1`)** — the lmarena credential hint asked for a cookie named `session`, but lmarena.ai's real auth cookie is `arena-auth-prod-v1`, so users who pasted only `session=…` hit validation failures. The credential name, placeholder and storage keys now use the correct name (the legacy `session` key is retained for back-compat with already-saved credentials). ([#3810](https://github.com/diegosouzapw/OmniRoute/issues/3810) — thanks @xspylol)
 
diff --git a/src/sse/handlers/chat.ts b/src/sse/handlers/chat.ts
index e8bb5317a8..78dabc2919 100644
--- a/src/sse/handlers/chat.ts
+++ b/src/sse/handlers/chat.ts
@@ -53,6 +53,7 @@ import {
   handleNoCredentials,
   safeResolveProxy,
   safeLogEvents,
+  shouldRetryStreamEarlyEof,
   withSessionHeader,
 } from "./chatHelpers";
 import { connectionHasExtraKeys } from "@omniroute/open-sse/services/apiKeyRotator.ts";
@@ -98,10 +99,7 @@ import {
   resolveCooldownAwareRetrySettings,
   waitForCooldownAwareRetry,
 } from "../services/cooldownAwareRetry";
-import {
-  constrainConnectionsToQuota,
-  resolveQuotaKeyScope,
-} from "../../lib/quota/quotaKey";
+import { constrainConnectionsToQuota, resolveQuotaKeyScope } from "../../lib/quota/quotaKey";
 
 registerCodexQuotaFetcher();
 
@@ -772,7 +770,14 @@ async function handleSingleModelChat(
     });
   }
 
-  const { provider: resolvedProvider, model, sourceFormat, targetFormat, extendedContext, apiFormat } = resolved;
+  const {
+    provider: resolvedProvider,
+    model,
+    sourceFormat,
+    targetFormat,
+    extendedContext,
+    apiFormat,
+  } = resolved;
   // Prefer the combo target's providerId when available — the model string's
   // provider prefix may differ from the credential provider ID (e.g. model
   // "xiaomi/mimo-v2-flash" resolves to provider "xiaomi" but the combo target
@@ -877,6 +882,10 @@ async function handleSingleModelChat(
   let requestRetryLastError = null;
   let requestRetryLastStatus = null;
   let requestRetryLastCooldownMs = 0;
+  // Bug #3758: per-request counter bounding the early-close (STREAM_EARLY_EOF)
+  // re-attempt to exactly one for the whole request. Declared outside both retry
+  // loops so it can never reset and loop.
+  let streamEarlyEofRetries = 0;
 
   requestAttemptLoop: while (true) {
     const excludedConnectionIds = new Set<string>();
@@ -1097,6 +1106,27 @@ async function handleSingleModelChat(
         (result.errorType === "stream_timeout" || result.errorType === "stream_early_eof") &&
         !isAntigravityStreamReadinessFailure
       ) {
+        // Bug #3758: flaky OpenAI-compatible upstreams (e.g. NVIDIA NIM) sometimes
+        // send HTTP 200 then close the SSE early with zero useful frames
+        // (STREAM_EARLY_EOF). That is a transient upstream glitch, not a bad key — so
+        // allow exactly ONE bounded same-connection re-attempt before surfacing the
+        // 502. Do NOT retry STREAM_READINESS_TIMEOUT (a slow-but-alive upstream;
+        // retrying would only double latency) and do NOT mark the account unavailable
+        // for the early close.
+        if (
+          shouldRetryStreamEarlyEof(result.errorCode, streamEarlyEofRetries) &&
+          !hasForcedConnection
+        ) {
+          streamEarlyEofRetries += 1;
+          log.warn(
+            "STREAM",
+            `${provider}/${model} closed the stream early before useful content — retrying once (attempt ${streamEarlyEofRetries})`
+          );
+          // Plain re-attempt of the same request: no markAccountUnavailable, no
+          // excludedConnectionIds mutation (an early close is not a bad connection).
+          continue;
+        }
+
         // Stream readiness timeout is an upstream stall after an HTTP response was received,
         // not an account/quota failure. Do NOT mark the account unavailable here.
         return result.response;
@@ -1357,8 +1387,11 @@ async function handleSingleModelChat(
             model,
             providerProfile,
             {
-              persistUnavailableState:
-                !(isCombo && result.status === 429 && (failureKind === "rate_limit" || failureKind === "transient")),
+              persistUnavailableState: !(
+                isCombo &&
+                result.status === 429 &&
+                (failureKind === "rate_limit" || failureKind === "transient")
+              ),
               isCombo,
             }
           );
diff --git a/src/sse/handlers/chatHelpers.ts b/src/sse/handlers/chatHelpers.ts
index 458a2c0079..94030c6694 100644
--- a/src/sse/handlers/chatHelpers.ts
+++ b/src/sse/handlers/chatHelpers.ts
@@ -582,6 +582,35 @@ export function handleNoCredentials(
   );
 }
 
+/**
+ * Bug #3758 (Problem A): NVIDIA NIM (and other flaky OpenAI-compatible upstreams)
+ * intermittently send HTTP 200, then close the SSE early with zero useful frames.
+ * The readiness gate surfaces this as `STREAM_EARLY_EOF` / HTTP 502. On the
+ * single-model (non-combo) path that 502 used to be returned immediately for every
+ * provider except `antigravity`, so a transient upstream hang-up looked like a hard
+ * failure to the caller (e.g. the test-chat scenario).
+ *
+ * This decides whether a single-model request should re-attempt after an early
+ * close. It deliberately:
+ *  - retries ONLY on `STREAM_EARLY_EOF` (the strong "upstream hung up after 200"
+ *    signal) — NOT on `STREAM_READINESS_TIMEOUT` / `stream_timeout`, which is a
+ *    slow-but-alive upstream where retrying would only double latency; and
+ *  - is bounded to exactly ONE retry via the per-request `attempt` counter, so it
+ *    can never loop (the second consecutive early close surfaces the 502).
+ *
+ * Pure function (no side effects): the caller performs a plain same-connection
+ * re-attempt and must NOT mark the account unavailable for an early close — it is a
+ * transient upstream glitch, not a bad key.
+ */
+export const STREAM_EARLY_EOF_MAX_RETRIES = 1;
+
+export function shouldRetryStreamEarlyEof(
+  errorCode: string | null | undefined,
+  attempt: number
+): boolean {
+  return errorCode === "STREAM_EARLY_EOF" && attempt < STREAM_EARLY_EOF_MAX_RETRIES;
+}
+
 /**
  * Proxy-resolution failure policy. Default: fail-closed (rethrow) so a request
  * with an assigned-but-unresolvable proxy never silently egresses on the real IP.
diff --git a/tests/unit/stream-early-eof-retry-3758.test.ts b/tests/unit/stream-early-eof-retry-3758.test.ts
new file mode 100644
index 0000000000..135d1adda2
--- /dev/null
+++ b/tests/unit/stream-early-eof-retry-3758.test.ts
@@ -0,0 +1,101 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+// Bug #3758 (Problem A): NVIDIA NIM models intermittently send HTTP 200 then close
+// the SSE early with zero useful frames (flaky upstream early-close). The readiness
+// gate correctly surfaces STREAM_EARLY_EOF / HTTP 502, but on the single-model path
+// only `antigravity` got an early-close retry — every other OpenAI-compatible
+// provider returned the 502 immediately with no retry.
+//
+// The fix generalizes the early-close handling: on `STREAM_EARLY_EOF` for ANY
+// provider on the single-model path, allow exactly ONE bounded re-attempt before
+// surfacing the 502. The decision lives in the pure helper
+// `shouldRetryStreamEarlyEof(errorCode, attempt)` so it can be unit-tested in
+// isolation and can NEVER loop.
+
+const { shouldRetryStreamEarlyEof } = await import("../../src/sse/handlers/chatHelpers.ts");
+
+test("shouldRetryStreamEarlyEof: retries once on the first STREAM_EARLY_EOF (attempt 0)", () => {
+  // Attempt 1 returned 200 then closed the SSE early → STREAM_EARLY_EOF.
+  // A non-antigravity provider (e.g. nvidia) must RETRY ONCE, not return the 502.
+  assert.equal(shouldRetryStreamEarlyEof("STREAM_EARLY_EOF", 0), true);
+});
+
+test("shouldRetryStreamEarlyEof: does NOT retry a second consecutive early-close (bounded)", () => {
+  // Two consecutive early-closes → the second one returns the 502 (exactly one retry, no loop).
+  assert.equal(shouldRetryStreamEarlyEof("STREAM_EARLY_EOF", 1), false);
+  assert.equal(shouldRetryStreamEarlyEof("STREAM_EARLY_EOF", 2), false);
+  assert.equal(shouldRetryStreamEarlyEof("STREAM_EARLY_EOF", 99), false);
+});
+
+test("shouldRetryStreamEarlyEof: does NOT retry a stream readiness TIMEOUT (preserves latency)", () => {
+  // A slow-but-alive upstream (STREAM_READINESS_TIMEOUT / stream_timeout) must NOT
+  // be retried — retrying would double latency for a request that is still warming up.
+  assert.equal(shouldRetryStreamEarlyEof("STREAM_READINESS_TIMEOUT", 0), false);
+  assert.equal(shouldRetryStreamEarlyEof("stream_timeout", 0), false);
+});
+
+test("shouldRetryStreamEarlyEof: ignores unrelated/empty error codes", () => {
+  assert.equal(shouldRetryStreamEarlyEof("", 0), false);
+  assert.equal(shouldRetryStreamEarlyEof(null, 0), false);
+  assert.equal(shouldRetryStreamEarlyEof(undefined, 0), false);
+  assert.equal(shouldRetryStreamEarlyEof("UPSTREAM_4XX", 0), false);
+  assert.equal(shouldRetryStreamEarlyEof("account_semaphore_capacity", 0), false);
+});
+
+// Behavioral end-to-end of the single-model path: stub executeChatWithBreaker so
+// attempt 1 returns a STREAM_EARLY_EOF result and attempt 2 returns a successful
+// stream. Assert the handler retries ONCE on the same connection, returns the
+// successful stream, and never calls markAccountUnavailable for the early-close.
+//
+// Driving the full handler in a unit test is heavy (DB, auth, breaker), so this
+// block mirrors the exact decision wiring the handler uses around the
+// STREAM_EARLY_EOF branch, using the pure helper as the single source of truth.
+test("single-model early-close: retries once then succeeds; double early-close surfaces 502; no markAccountUnavailable", () => {
+  // Simulated per-request early-EOF attempt counter, mirroring chat.ts.
+  function simulate(results: Array<{ errorCode: string; success?: boolean }>) {
+    let earlyEofAttempts = 0;
+    let markAccountUnavailableCalls = 0;
+    let i = 0;
+
+    while (true) {
+      const result = results[Math.min(i, results.length - 1)];
+      if (result.success) {
+        return { outcome: "success", earlyEofAttempts, markAccountUnavailableCalls };
+      }
+
+      // Non-antigravity early-close: never marks the account unavailable.
+      if (shouldRetryStreamEarlyEof(result.errorCode, earlyEofAttempts)) {
+        earlyEofAttempts += 1;
+        i += 1;
+        continue;
+      }
+
+      // Falls through to the immediate 502 return.
+      return { outcome: "502", earlyEofAttempts, markAccountUnavailableCalls };
+    }
+  }
+
+  // attempt 1: early-close → retry; attempt 2: success
+  const recovered = simulate([
+    { errorCode: "STREAM_EARLY_EOF" },
+    { errorCode: "STREAM_EARLY_EOF", success: true },
+  ]);
+  assert.equal(recovered.outcome, "success");
+  assert.equal(recovered.earlyEofAttempts, 1, "exactly one retry before success");
+  assert.equal(
+    recovered.markAccountUnavailableCalls,
+    0,
+    "early-close must not mark account unavailable"
+  );
+
+  // attempt 1 + attempt 2 both early-close → surfaces the 502 (bounded, no loop)
+  const exhausted = simulate([
+    { errorCode: "STREAM_EARLY_EOF" },
+    { errorCode: "STREAM_EARLY_EOF" },
+    { errorCode: "STREAM_EARLY_EOF" },
+  ]);
+  assert.equal(exhausted.outcome, "502");
+  assert.equal(exhausted.earlyEofAttempts, 1, "only one retry attempted before surfacing 502");
+  assert.equal(exhausted.markAccountUnavailableCalls, 0);
+});