diff --git a/.changeset/openai-gpt-5-6-byok.md b/.changeset/openai-gpt-5-6-byok.md
new file mode 100644
index 0000000000..ed92b6c80e
--- /dev/null
+++ b/.changeset/openai-gpt-5-6-byok.md
@@ -0,0 +1,16 @@
+---
+"@mcpjam/inspector": patch
+---
+
+GPT-5.6 is selectable with your own OpenAI key.
+
+The BYOK OpenAI rows are hand-maintained and had stopped at GPT-5.1 while the
+hosted catalog was already serving `gpt-5.6-luna`, `-sol` and `-terra`, so a
+user with a valid key could not pick the models MCPJam already serves for free.
+All three now lead the OpenAI group, with the 1,050,000-token context the
+catalog reports.
+
+Token counting maps them to GPT-5, the closest id ai-tokenizer knows; an
+approximate count beats dropping to the character-based fallback. Temperature
+needed no new handling — the `gpt-5` carve-out in `modelSupportsTemperature`
+already matches these ids, so the field is omitted rather than sent.
diff --git a/mcpjam-inspector/server/utils/tokenizer-helpers.ts b/mcpjam-inspector/server/utils/tokenizer-helpers.ts
index aa5ca74a2c..2de3650dc1 100644
--- a/mcpjam-inspector/server/utils/tokenizer-helpers.ts
+++ b/mcpjam-inspector/server/utils/tokenizer-helpers.ts
@@ -48,6 +48,9 @@ const MODEL_ID_MAPPINGS: Record<string, string> = {
   "gpt-5.1-codex-mini": "openai/gpt-5.1-codex-mini",
   "gpt-5.5": "openai/gpt-5",
   "openai/gpt-5.5": "openai/gpt-5",
+  "gpt-5.6-luna": "openai/gpt-5", // Map to closest available
+  "gpt-5.6-sol": "openai/gpt-5",
+  "gpt-5.6-terra": "openai/gpt-5",
 
   // DeepSeek models
   "deepseek-chat": "deepseek/deepseek-v3.1",
diff --git a/mcpjam-inspector/shared/__tests__/types.test.ts b/mcpjam-inspector/shared/__tests__/types.test.ts
index 685834aca8..bbdc7891f4 100644
--- a/mcpjam-inspector/shared/__tests__/types.test.ts
+++ b/mcpjam-inspector/shared/__tests__/types.test.ts
@@ -153,6 +153,17 @@ describe("MCPJam-provided model classification", () => {
     }
   });
 
+  it("offers the current OpenAI models to BYOK keys", () => {
+    // BYOK rows are hand-maintained and had drifted to 5.1. See BACK2-714.
+    const openaiIds = SUPPORTED_MODELS.filter(
+      (m) => m.provider === "openai",
+    ).map((m) => String(m.id));
+
+    for (const id of ["gpt-5.6-luna", "gpt-5.6-sol", "gpt-5.6-terra"]) {
+      expect(openaiIds).toContain(id);
+    }
+  });
+
   it("reports no temperature support for the Anthropic rows that reject it", () => {
     // Fable 5, Opus 5, Opus 4.8/4.7 and Sonnet 5 answer a temperature with a
     // 400, so every one of these rows would fail on its first request while
@@ -226,6 +237,7 @@ describe("modelSupportsTemperature", () => {
   it("still strips temperature for own-provider GPT-5 models", () => {
     expect(modelSupportsTemperature("gpt-5")).toBe(false);
     expect(modelSupportsTemperature("gpt-5.1-codex")).toBe(false);
+    expect(modelSupportsTemperature("gpt-5.6-luna")).toBe(false);
   });
 
   it("strips temperature for a hosted GPT-5 too", () => {
diff --git a/mcpjam-inspector/shared/types.ts b/mcpjam-inspector/shared/types.ts
index 9e1c47dd1f..f1eb483768 100644
--- a/mcpjam-inspector/shared/types.ts
+++ b/mcpjam-inspector/shared/types.ts
@@ -359,6 +359,9 @@ export enum Model {
   GPT_5_1 = "gpt-5.1",
   GPT_5_1_CODEX = "gpt-5.1-codex",
   GPT_5_1_CODEX_MINI = "gpt-5.1-codex-mini",
+  GPT_5_6_LUNA = "gpt-5.6-luna",
+  GPT_5_6_SOL = "gpt-5.6-sol",
+  GPT_5_6_TERRA = "gpt-5.6-terra",
   GPT_3_5_TURBO = "gpt-3.5-turbo",
   DEEPSEEK_CHAT = "deepseek-chat",
   DEEPSEEK_REASONER = "deepseek-reasoner",
@@ -454,6 +457,24 @@ export const SUPPORTED_MODELS: ModelDefinition[] = [
     provider: "anthropic",
     contextLength: 200000,
   },
+  {
+    id: Model.GPT_5_6_LUNA,
+    name: "GPT-5.6 Luna",
+    provider: "openai",
+    contextLength: 1050000,
+  },
+  {
+    id: Model.GPT_5_6_SOL,
+    name: "GPT-5.6 Sol",
+    provider: "openai",
+    contextLength: 1050000,
+  },
+  {
+    id: Model.GPT_5_6_TERRA,
+    name: "GPT-5.6 Terra",
+    provider: "openai",
+    contextLength: 1050000,
+  },
   {
     id: Model.GPT_5_1,
     name: "GPT-5.1",