diff --git a/changelog.d/fixes/12898-combo-hidden-update-schema.md b/changelog.d/fixes/12898-combo-hidden-update-schema.md
new file mode 100644
index 0000000000..190a86682c
--- /dev/null
+++ b/changelog.d/fixes/12898-combo-hidden-update-schema.md
@@ -0,0 +1 @@
+- **fix(combos):** A combo's visibility can be changed through the API again: `updateComboSchema` accepts `isHidden`, so a visibility-only update is no longer rejected as empty and a mixed update no longer drops it ([#12898](https://github.com/diegosouzapw/OmniRoute/pull/12898), closes [#12836](https://github.com/diegosouzapw/OmniRoute/issues/12836))
diff --git a/src/shared/validation/schemas/combo.ts b/src/shared/validation/schemas/combo.ts
index a9349dfd61..1cd3e28377 100644
--- a/src/shared/validation/schemas/combo.ts
+++ b/src/shared/validation/schemas/combo.ts
@@ -419,6 +419,11 @@ export const updateComboSchema = z
     strategy: comboStrategySchema.optional(),
     config: comboRuntimeConfigSchema.optional(),
     isActive: z.boolean().optional(),
+    // Stored on the combo record and honoured by the readers — the builder's
+    // option list and the dashboard grid both filter on it — but omitted here,
+    // so the one endpoint a client can flip it through stripped the field and
+    // a visibility-only update was rejected as empty. #12836
+    isHidden: z.boolean().optional(),
     allowedProviders: z.array(z.string().trim().min(1).max(200)).max(100).optional(),
     allowedModelFamilies: z.array(z.string().trim().min(1).max(100)).max(100).optional(),
     // Nullable like `description` and `context_length` above: an absent field means
@@ -443,6 +448,7 @@ export const updateComboSchema = z
       value.strategy === undefined &&
       value.config === undefined &&
       value.isActive === undefined &&
+      value.isHidden === undefined &&
       value.allowedProviders === undefined &&
       value.allowedModelFamilies === undefined &&
       value.system_message === undefined &&
diff --git a/tests/unit/combo-hidden-update-12836.test.ts b/tests/unit/combo-hidden-update-12836.test.ts
new file mode 100644
index 0000000000..4e39cd6103
--- /dev/null
+++ b/tests/unit/combo-hidden-update-12836.test.ts
@@ -0,0 +1,102 @@
+/**
+ * #12836 — a combo's visibility must be updatable through the API.
+ *
+ * `isHidden` is stored on the combo record and honoured by its readers: the
+ * builder's option list drops hidden combos (`src/lib/combos/builderOptions.ts`)
+ * and so does the dashboard grid. `createCombo` writes the field explicitly.
+ * The only endpoint a client can flip it through is `PUT /api/combos/[id]`,
+ * which spreads the *validated* body into the update — and `updateComboSchema`
+ * never listed `isHidden`, so zod stripped it. A visibility-only update was
+ * rejected as "No valid fields to update", and pairing it with a recognized
+ * field made the request succeed while silently dropping the visibility change.
+ */
+import test from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-combo-hidden-12836-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+const { updateComboSchema } = await import("../../src/shared/validation/schemas.ts");
+const core = await import("../../src/lib/db/core.ts");
+const combosDb = await import("../../src/lib/db/combos.ts");
+
+async function resetStorage() {
+  core.resetDbInstance();
+  if (fs.existsSync(TEST_DATA_DIR)) {
+    fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+  }
+  fs.mkdirSync(TEST_DATA_DIR, { recursive: true });
+}
+
+test.beforeEach(async () => {
+  await resetStorage();
+});
+
+test.after(async () => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+test("#12836 a visibility-only update is a valid update", () => {
+  assert.equal(updateComboSchema.parse({ isHidden: true }).isHidden, true);
+  assert.equal(updateComboSchema.parse({ isHidden: false }).isHidden, false);
+  // The empty-update refinement still fires for a genuinely empty body.
+  assert.throws(() => updateComboSchema.parse({}), /No valid fields to update/);
+});
+
+test("#12836 visibility survives a mixed update instead of being stripped", () => {
+  const parsed = updateComboSchema.parse({ description: "fixture", isHidden: true });
+  assert.equal(parsed.description, "fixture");
+  assert.equal(parsed.isHidden, true);
+});
+
+test("#12836 only a boolean is accepted", () => {
+  for (const bad of ["true", 1, null, {}]) {
+    assert.throws(() => updateComboSchema.parse({ isHidden: bad }));
+  }
+});
+
+test("#12836 hiding a combo persists and reads back", async () => {
+  const created = await combosDb.createCombo({
+    name: "Visibility Combo",
+    models: [{ provider: "openai", model: "gpt-4.1" }],
+  });
+  assert.equal(created.isHidden, false);
+
+  const body = updateComboSchema.parse({ isHidden: true });
+  const updated = await combosDb.updateCombo(created.id as string, body);
+  assert.ok(updated);
+  assert.equal(updated!.isHidden, true);
+
+  // Re-read: this is the state the builder and the dashboard grid filter on.
+  const reread = await combosDb.getComboById(created.id as string);
+  assert.ok(reread);
+  assert.equal(reread!.isHidden, true);
+});
+
+test("#12836 unhiding it again works, and an unrelated update leaves it alone", async () => {
+  const created = await combosDb.createCombo({
+    name: "Round Trip Combo",
+    models: [{ provider: "openai", model: "gpt-4.1" }],
+  });
+
+  await combosDb.updateCombo(created.id as string, updateComboSchema.parse({ isHidden: true }));
+  const shown = await combosDb.updateCombo(
+    created.id as string,
+    updateComboSchema.parse({ isHidden: false })
+  );
+  assert.ok(shown);
+  assert.equal(shown!.isHidden, false);
+
+  await combosDb.updateCombo(created.id as string, updateComboSchema.parse({ isHidden: true }));
+  const untouched = await combosDb.updateCombo(
+    created.id as string,
+    updateComboSchema.parse({ description: "note" })
+  );
+  assert.ok(untouched);
+  assert.equal(untouched!.description, "note");
+  assert.equal(untouched!.isHidden, true);
+});