diff --git a/open-sse/config/providerRegistry.ts b/open-sse/config/providerRegistry.ts
index 64c6416b24..08a3f4b099 100644
--- a/open-sse/config/providerRegistry.ts
+++ b/open-sse/config/providerRegistry.ts
@@ -252,9 +252,9 @@ function ensureUnsupportedParamsPopulated(): void {
  */
 export function getUnsupportedParams(provider: string, modelId: string): readonly string[] {
   ensureUnsupportedParamsPopulated();
-  // 1. Check current provider's registry (exact match)
+  // 1. Check current provider's registry (exact match, then declared aliases)
   const entry = getRegistryEntry(provider);
-  const modelEntry = entry?.models?.find((m) => m.id === modelId);
+  const modelEntry = entry?.models?.find((m) => m.id === modelId || m.aliases?.includes(modelId));
   if (modelEntry?.unsupportedParams) return modelEntry.unsupportedParams;
 
   // 2. O(1) lookup in precomputed map (handles cross-provider routing)
diff --git a/open-sse/config/providers/registry/moonshot/index.ts b/open-sse/config/providers/registry/moonshot/index.ts
index 07459210e7..76e9bd6b93 100644
--- a/open-sse/config/providers/registry/moonshot/index.ts
+++ b/open-sse/config/providers/registry/moonshot/index.ts
@@ -5,6 +5,12 @@ import { REASONING_UNSUPPORTED, type RegistryEntry, type RegistryModel } from ".
 export const KIMI_K3_MODEL: RegistryModel = {
   id: "kimi-k3",
   name: "Kimi K3",
+  // Moonshot's LIVE catalogue serves this model as `k3` and `k3-256k` (the
+  // 256K-context cut), NOT as `kimi-k3`. Both spellings must resolve to this
+  // entry or `getUnsupportedParams` returns [] and temperature reaches an
+  // upstream that hard-400s ("invalid temperature: only 1 is allowed for this
+  // model") — which silently drops the target out of every combo it sits in.
+  aliases: ["k3", "k3-256k"],
   contextLength: 1048576,
   maxOutputTokens: 1048576,
   supportsVision: true,
diff --git a/tests/unit/moonshot-k3-unsupported-params-aliases.test.ts b/tests/unit/moonshot-k3-unsupported-params-aliases.test.ts
new file mode 100644
index 0000000000..8fb1d86199
--- /dev/null
+++ b/tests/unit/moonshot-k3-unsupported-params-aliases.test.ts
@@ -0,0 +1,67 @@
+// tests/unit/moonshot-k3-unsupported-params-aliases.test.ts
+//
+// Live incident (2026-09-07): every `moonshot/k3-256k` hop in the `judge` and
+// `best-reasoning-paid` combos hard-400'd with
+//   "invalid temperature: only 1 is allowed for this model"
+// because the registry catalogues the model as `kimi-k3` while Moonshot's live
+// catalogue serves it as `k3` / `k3-256k`. `getUnsupportedParams` matched on the
+// canonical id only, returned [], and temperature was forwarded upstream.
+//
+// The kimi-coding provider (`kmc`/`kmca`) serves its OWN `k3`/`k3-256k` over the
+// Anthropic-format path and DOES accept temperature — verified live: temp=0
+// returns 200 there. So the resolution must stay provider-scoped; a global
+// alias index would wrongly strip temperature for kimi-coding.
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { getUnsupportedParams } from "../../open-sse/config/providerRegistry.ts";
+
+const stripsTemperature = (provider: string, modelId: string): boolean =>
+  getUnsupportedParams(provider, modelId).includes("temperature");
+
+test("moonshot live K3 ids resolve to the kimi-k3 reasoning restrictions", () => {
+  for (const modelId of ["k3", "k3-256k", "kimi-k3"]) {
+    assert.equal(
+      stripsTemperature("moonshot", modelId),
+      true,
+      `moonshot/${modelId} must strip temperature`
+    );
+  }
+});
+
+test("the kimi provider shares the moonshot catalogue and resolves the same aliases", () => {
+  assert.equal(stripsTemperature("kimi", "k3-256k"), true);
+  assert.equal(stripsTemperature("kimi", "k3"), true);
+});
+
+test("full REASONING_UNSUPPORTED set resolves via alias, not just temperature", () => {
+  const viaAlias = getUnsupportedParams("moonshot", "k3-256k");
+  const viaCanonical = getUnsupportedParams("moonshot", "kimi-k3");
+  assert.deepEqual([...viaAlias], [...viaCanonical]);
+  for (const param of ["temperature", "top_p", "frequency_penalty", "n"]) {
+    assert.ok(viaAlias.includes(param), `expected ${param} in alias-resolved params`);
+  }
+});
+
+test("kimi-coding keeps temperature — its k3 ids are a DIFFERENT upstream that accepts it", () => {
+  for (const provider of ["kimi-coding", "kmc", "kimi-coding-apikey", "kmca"]) {
+    for (const modelId of ["k3", "k3-256k"]) {
+      assert.equal(
+        stripsTemperature(provider, modelId),
+        false,
+        `${provider}/${modelId} must NOT strip temperature`
+      );
+    }
+  }
+});
+
+test("non-K3 moonshot models are unaffected by the alias resolution", () => {
+  // kimi-for-coding has no unsupportedParams and accepts temperature live.
+  assert.equal(stripsTemperature("moonshot", "kimi-for-coding"), false);
+  // Sibling reasoning models keep their existing restrictions.
+  assert.equal(stripsTemperature("moonshot", "kimi-k2.7-code"), true);
+  assert.equal(stripsTemperature("moonshot", "kimi-k2.6"), true);
+});
+
+test("an unknown model id still resolves to no restrictions", () => {
+  assert.deepEqual([...getUnsupportedParams("moonshot", "definitely-not-a-model")], []);
+});