diff --git a/changelog.d/fixes/12371-kimi-k3-effort-tiers.md b/changelog.d/fixes/12371-kimi-k3-effort-tiers.md
new file mode 100644
index 0000000000..49a3310761
--- /dev/null
+++ b/changelog.d/fixes/12371-kimi-k3-effort-tiers.md
@@ -0,0 +1 @@
+- **fix(models):** publish `effort_tiers` on Kimi K3's synced base-model entries (`kmca/k3`, `kmca/k3-256k`) so catalog-only clients (OpenCode, plain SDK pickers) can see and select the reasoning tiers (`low`/`high`/`max`) the synced metadata already carried — the `isSkippedEffortProvider` gate no longer suppresses tier visibility on those base entries, while synthetic `<id>-<tier>` variant generation stays prevented and Codex/GLM base models remain excluded unchanged ([#12299](https://github.com/diegosouzapw/OmniRoute/issues/12299))
diff --git a/src/app/api/v1/models/syncedCapabilities.ts b/src/app/api/v1/models/syncedCapabilities.ts
index 529753a8d9..aac6f9fd27 100644
--- a/src/app/api/v1/models/syncedCapabilities.ts
+++ b/src/app/api/v1/models/syncedCapabilities.ts
@@ -21,6 +21,12 @@
  * `<id>-<tier>` catalog entries (open-sse/utils/syncedEffortVariants.ts) — it
  * never runs over the base entry's `capabilities`, so it cannot substitute
  * for this check. Required (not optional) so no call site can silently skip it.
+ *
+ * #12299 carve-out: Kimi K3's synced base entries (`k3`, `k3-256k` — the kmca
+ * catalog's `low`/`high`/`max` vocabulary) are exempted from the exclusion so
+ * catalog-only clients (OpenCode, plain SDK pickers) can see and select their
+ * tiers. Model-scoped, never provider-wide: Codex, GLM, and non-K3 kimi models
+ * keep the full exclusion exactly as before this carve-out.
  */
 // Use the same canonical alias as catalogModelPolicy.ts (l.1) — a relative path from
 // src/app/api/v1/models/ to open-sse/ would need 5 `../` and silently breaks under
@@ -39,8 +45,30 @@ interface SyncedCapabilityFlags {
   supportedThinkingEfforts?: string[];
 }
 
+// Model-id pattern for the Kimi K3 family (#12299): the kmca catalog syncs
+// `k3`/`k3-256k` (and prefixed forms such as `kmca/k3`). Same shape the
+// executor/translator layers use to recognize K3 elsewhere
+// (reasoningContentInjector.ts::K3_AUTHENTIC_REASONING_PATTERN).
+const KIMI_K3_MODEL_ID_PATTERN = /(?:^|\/)(?:kimi-)?k3(?:$|-)/i;
+
+/**
+ * #12299: only Kimi K3's synced BASE entries are exempt from the
+ * `isSkippedEffortProvider` exclusion. Model-scoped, never provider-wide —
+ * the exemption requires a kimi-owned provider AND a K3 model id, so Codex,
+ * GLM, and non-K3 kimi models keep the exclusion contract from #7694.
+ */
+function isExemptKimiK3BaseModel(sm: SyncedCapabilityFlags, ownedBy: string): boolean {
+  return (
+    ownedBy.startsWith("kimi") && typeof sm.id === "string" && KIMI_K3_MODEL_ID_PATTERN.test(sm.id)
+  );
+}
+
 function effectiveEffortTiers(sm: SyncedCapabilityFlags, ownedBy: string): string[] | undefined {
-  if (isSkippedEffortProvider(ownedBy)) return undefined;
+  // Exclusion gate (#7694): codex/glm/kimi own a conflicting `-{effort}` suffix
+  // mechanism — the blind opencode-plugin mapping must never see effort_tiers
+  // for them, or it double-handles the suffix. #12299 narrows only the kimi K3
+  // base-model entries out of that gate; everything else stays excluded.
+  if (isSkippedEffortProvider(ownedBy) && !isExemptKimiK3BaseModel(sm, ownedBy)) return undefined;
   const learned = sm.id ? getLearnedReasoningEffortForModel(sm.id) : null;
   const synced =
     Array.isArray(sm.supportedThinkingEfforts) && sm.supportedThinkingEfforts.length > 0
diff --git a/tests/unit/kimi-k3-effort-tiers-12299.test.ts b/tests/unit/kimi-k3-effort-tiers-12299.test.ts
new file mode 100644
index 0000000000..d4e0619c6b
--- /dev/null
+++ b/tests/unit/kimi-k3-effort-tiers-12299.test.ts
@@ -0,0 +1,103 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import path from "node:path";
+import {
+  buildSyncedCapabilities,
+  mergeSyncedCapabilities,
+} from "../../src/app/api/v1/models/syncedCapabilities.ts";
+import {
+  shouldExposeSyncedEffortVariants,
+  appendSyncedEffortVariants,
+} from "../../open-sse/utils/syncedEffortVariants.ts";
+
+// #12299: Kimi K3's supportedThinkingEfforts (["low", "high", "max"]) were
+// suppressed on the BASE model by isSkippedEffortProvider in
+// effectiveEffortTiers(), leaving catalog-only clients with no tiers to copy.
+// Fix: publish effort_tiers on the base model while still preventing
+// synthetic <id>-<tier> variant generation for kimi providers.
+
+const KIMI_K3_TIERS = ["low", "high", "max"];
+
+test("Kimi K3 base model publishes effort_tiers via buildSyncedCapabilities (#12299)", () => {
+  const caps = buildSyncedCapabilities(
+    { id: "k3", supportsThinking: true, supportedThinkingEfforts: KIMI_K3_TIERS },
+    "kimi-coding-apikey"
+  );
+  assert.ok(caps, "capabilities must be defined for kimi K3");
+  assert.deepEqual(
+    caps.effort_tiers,
+    KIMI_K3_TIERS,
+    "kimi K3 base model must publish effort_tiers low/high/max"
+  );
+});
+
+test("Kimi K3-256k base model publishes effort_tiers via buildSyncedCapabilities (#12299)", () => {
+  const caps = buildSyncedCapabilities(
+    { id: "k3-256k", supportsThinking: true, supportedThinkingEfforts: KIMI_K3_TIERS },
+    "kimi-coding-apikey"
+  );
+  assert.ok(caps, "capabilities must be defined for kimi K3-256k");
+  assert.deepEqual(
+    caps.effort_tiers,
+    KIMI_K3_TIERS,
+    "kimi K3-256k base model must publish effort_tiers low/high/max"
+  );
+});
+
+test("Kimi K3 merge path also publishes effort_tiers (#12299)", () => {
+  const merged = mergeSyncedCapabilities(
+    { tool_calling: true },
+    { id: "k3", supportsThinking: true, supportedThinkingEfforts: KIMI_K3_TIERS },
+    "kimi-coding-apikey"
+  );
+  assert.ok(merged, "merged capabilities must be defined");
+  assert.deepEqual(
+    merged.effort_tiers,
+    KIMI_K3_TIERS,
+    "merge path must publish kimi K3 effort_tiers"
+  );
+  assert.equal(merged.tool_calling, true, "existing tool_calling must be preserved");
+});
+
+test("shouldExposeSyncedEffortVariants still prevents synthetic kimi variants", () => {
+  // The base model should NOT generate synthetic <id>-<tier> entries
+  assert.equal(
+    shouldExposeSyncedEffortVariants({
+      id: "kimi/k3",
+      owned_by: "kimi-coding-apikey",
+      capabilities: { effort_tiers: KIMI_K3_TIERS },
+    }),
+    false,
+    "must not generate synthetic kimi/k3-low, kimi/k3-high, etc."
+  );
+});
+
+test("appendSyncedEffortVariants does not create kimi variant entries", () => {
+  const models = [
+    {
+      id: "kimi-coding-apikey/k3",
+      owned_by: "kimi-coding-apikey",
+      capabilities: { effort_tiers: KIMI_K3_TIERS },
+    },
+  ];
+  const result = appendSyncedEffortVariants(models);
+  assert.equal(result.length, 1, "must not add synthetic variant entries for kimi");
+  assert.equal(result[0].id, "kimi-coding-apikey/k3", "original entry must be unchanged");
+});
+
+test("kimi K3 static registry tiers match synced metadata", () => {
+  // Verify the static registry in runtime.ts has the correct tiers
+  const runtimePath = path.join(
+    path.dirname(fileURLToPath(import.meta.url)),
+    "../../open-sse/config/providers/registry/kimi/coding/runtime.ts"
+  );
+  const content = readFileSync(runtimePath, "utf8");
+
+  // Verify the static thinking policies declare the same tiers
+  assert.ok(
+    content.includes('"low", "high", "max"'),
+    "KIMI_CODE_STATIC_THINKING_POLICIES.k3 must declare low/high/max"
+  );
+});
diff --git a/tests/unit/synced-capabilities-learned-effort-override.test.ts b/tests/unit/synced-capabilities-learned-effort-override.test.ts
index f33d08dc56..16f124b05b 100644
--- a/tests/unit/synced-capabilities-learned-effort-override.test.ts
+++ b/tests/unit/synced-capabilities-learned-effort-override.test.ts
@@ -62,6 +62,9 @@ test("merge path keeps vision AND applies the learned override", () => {
 // Exclusion gate (#7694): codex/glm/kimi already own a conflicting
 // `-{effort}` suffix mechanism — the blind opencode-plugin mapping must never
 // see effort_tiers for them, learned or synced, or it double-handles the suffix.
+// #12299 exempts only Kimi K3's BASE model entries (asserted in
+// tests/unit/kimi-k3-effort-tiers-12299.test.ts) — non-K3 kimi models such as
+// "excluded-model" below stay excluded alongside codex/glm.
 for (const ownedBy of ["codex", "glm", "glm-cn", "glmt", "kimi", "kimi-coding-apikey"]) {
   test(`build: excluded provider "${ownedBy}" never gets effort_tiers (synced)`, () => {
     const caps = buildSyncedCapabilities(