diff --git a/src/shared/validation/compressionConfigSchemas.ts b/src/shared/validation/compressionConfigSchemas.ts
index a9472c4227..bdebd8e63a 100644
--- a/src/shared/validation/compressionConfigSchemas.ts
+++ b/src/shared/validation/compressionConfigSchemas.ts
@@ -61,6 +61,7 @@ export const rtkConfigSchema = z
     groupingThreshold: z.number().int().min(2).max(100).optional(),
     stripCodeComments: z.boolean().optional(),
     preserveDocstrings: z.boolean().optional(),
+    enableRenderers: z.boolean().optional(),
   })
   .strict();
 
diff --git a/tests/unit/rtk-enable-renderers-6703.test.ts b/tests/unit/rtk-enable-renderers-6703.test.ts
new file mode 100644
index 0000000000..9674369a13
--- /dev/null
+++ b/tests/unit/rtk-enable-renderers-6703.test.ts
@@ -0,0 +1,41 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+
+import {
+  rtkConfigSchema,
+  compressionSettingsUpdateSchema,
+} from "../../src/shared/validation/compressionConfigSchemas.ts";
+import { DEFAULT_RTK_CONFIG } from "../../open-sse/services/compression/types.ts";
+
+// Regression for #6703: rtkConfigSchema uses Zod .strict() but was missing the
+// `enableRenderers` field that DEFAULT_RTK_CONFIG (and the RTK engine's own
+// configSchema) already define. The frontend reads DEFAULT_RTK_CONFIG (which
+// carries enableRenderers), sends the full object back on save, and .strict()
+// rejects the unknown key → HTTP 400 "Unrecognized key: enableRenderers".
+// This broke PUT /api/settings/compression, POST /api/context/rtk/test, and
+// PUT /api/context/rtk/config.
+
+describe("RTK config schema — enableRenderers (#6703)", () => {
+  it("accepts enableRenderers on the strict rtkConfigSchema", () => {
+    assert.equal(rtkConfigSchema.safeParse({ enableRenderers: false }).success, true);
+    assert.equal(rtkConfigSchema.safeParse({ enableRenderers: true }).success, true);
+  });
+
+  it("accepts the full DEFAULT_RTK_CONFIG without stripping fields", () => {
+    const result = rtkConfigSchema.safeParse(DEFAULT_RTK_CONFIG);
+    assert.equal(result.success, true, JSON.stringify(result.error?.issues));
+    assert.equal(result.data.enableRenderers, false);
+  });
+
+  it("rejects a genuinely unknown key (strict mode still enforced)", () => {
+    assert.equal(rtkConfigSchema.safeParse({ totallyBogusKey: true }).success, false);
+  });
+
+  it("accepts rtkConfig with enableRenderers through the settings-update schema", () => {
+    // Mirrors the PUT /api/settings/compression payload from the bug report.
+    const result = compressionSettingsUpdateSchema.safeParse({
+      rtkConfig: { ...DEFAULT_RTK_CONFIG, enableRenderers: false },
+    });
+    assert.equal(result.success, true, JSON.stringify(result.error?.issues));
+  });
+});