diff --git a/changelog.d/fixes/15164-gpt6-sol-luna-context-window.md b/changelog.d/fixes/15164-gpt6-sol-luna-context-window.md
new file mode 100644
index 000000000000..02b2880e851d
--- /dev/null
+++ b/changelog.d/fixes/15164-gpt6-sol-luna-context-window.md
@@ -0,0 +1 @@
+- fix(providers): add `gpt-6-sol` and `gpt-6-luna` to the OpenAI public API registry with the correct 1,050,000-token context window — they were missing and fell back to the 128k `defaultContextLength`, causing combos that included either model to advertise a capped-8x context window (#15023, #15164 — thanks @shipsfromrio)
diff --git a/open-sse/config/providers/registry/openai/index.ts b/open-sse/config/providers/registry/openai/index.ts
index d978fc5fe29d..4aa30a174274 100644
--- a/open-sse/config/providers/registry/openai/index.ts
+++ b/open-sse/config/providers/registry/openai/index.ts
@@ -21,6 +21,11 @@ export const openaiProvider: RegistryEntry = {
       supportedThinkingEfforts: ["low", "medium", "high", "xhigh", "max"],
       unsupportedParams: ["temperature", "top_p", "top_logprobs", "logprobs"],
     },
+    // #15023: Sol and Luna are GPT-6 siblings with the same public API context window as
+    // Astra (1,050,000). They were missing from this registry, causing the importer to
+    // fall back to defaultContextLength (128k) and corrupting combo context advertising.
+    { id: "gpt-6-sol", name: "GPT-6 Sol", ...GPT_5_6_API_CAPABILITIES },
+    { id: "gpt-6-luna", name: "GPT-6 Luna", ...GPT_5_6_API_CAPABILITIES },
     // #11489: per OpenAI's model reference `gpt-5.6` is an ALIAS of `gpt-5.6-sol`,
     // not a distinct model — quality scores point forward, which no suffix
     // stripper can express. Siblings `-terra`/`-luna` are their own models.
diff --git a/src/shared/constants/modelSpecs.ts b/src/shared/constants/modelSpecs.ts
index cb1a45a06df2..7a7ae5bd5f20 100644
--- a/src/shared/constants/modelSpecs.ts
+++ b/src/shared/constants/modelSpecs.ts
@@ -134,6 +134,18 @@ export const MODEL_SPECS: Record<string, ModelSpec> = {
     ...GPT_5_6_MODEL_SPEC,
     aliases: ["openai/gpt-6-astra"],
   },
+  // #15023: Sol and Luna were missing from the spec map; the public API context
+  // window is 1,050,000 (same as Astra). Without an entry, getModelSpec() returned
+  // undefined and any spec-aware path (capability filter, compaction guard) fell
+  // back to 128k, the same wrong value advertised by the importer.
+  "gpt-6-sol": {
+    ...GPT_5_6_MODEL_SPEC,
+    aliases: ["openai/gpt-6-sol"],
+  },
+  "gpt-6-luna": {
+    ...GPT_5_6_MODEL_SPEC,
+    aliases: ["openai/gpt-6-luna"],
+  },
   "gpt-6.1-sol": GPT_5_6_MODEL_SPEC,
   "gpt-5.6": {
     ...GPT_5_6_MODEL_SPEC,
diff --git a/src/shared/constants/pricing/frontier-labs.ts b/src/shared/constants/pricing/frontier-labs.ts
index 6ccbdc268bbe..dfe8a894cdaf 100644
--- a/src/shared/constants/pricing/frontier-labs.ts
+++ b/src/shared/constants/pricing/frontier-labs.ts
@@ -24,6 +24,17 @@ import {
 export const DEFAULT_PRICING_FRONTIER = {
   openai: {
     "gpt-6-astra": GPT_6_ASTRA_PRICING,
+    // Sol/Luna mirror the dollar-equivalent Codex Standard rates already used for the
+    // codex provider (oauth-subscriptions.ts) until OpenAI publishes distinct API rates;
+    // without these rows the openai registry entries resolved to $0 (catalog pricing gate).
+    "gpt-6-sol": { input: 2.0, output: 10.0, cached: 0.2, reasoning: 10.0, cache_creation: 2.5 },
+    "gpt-6-luna": {
+      input: 0.1,
+      output: 0.5,
+      cached: 0.01,
+      reasoning: 0.5,
+      cache_creation: 0.125,
+    },
     "gpt-6.1-sol": GPT_6_SOL_PRICING,
     "gpt-5.6": GPT_5_6_SOL_PRICING,
     "gpt-5.6-sol": GPT_5_6_SOL_PRICING,
diff --git a/tests/unit/openai-gpt56-catalog.test.ts b/tests/unit/openai-gpt56-catalog.test.ts
index c675af48fe78..4beb61b97bbd 100644
--- a/tests/unit/openai-gpt56-catalog.test.ts
+++ b/tests/unit/openai-gpt56-catalog.test.ts
@@ -9,9 +9,49 @@ import { DefaultExecutor } from "../../open-sse/executors/default.ts";
 import { resolveChatCoreTargetFormat } from "../../open-sse/handlers/chatCore/targetFormat.ts";
 import { openaiToOpenAIResponsesRequest } from "../../open-sse/translator/request/openai-responses/toResponses.ts";
 
-const EXPECTED_MODELS = ["gpt-6-astra", "gpt-5.6", "gpt-5.6-sol", "gpt-5.6-terra", "gpt-5.6-luna"];
+// Full GPT-6/5.6 family that the OpenAI public-API registry must expose in order.
+// gpt-6-sol and gpt-6-luna were added by #15023 (they were missing and fell back to
+// the 128k default, corrupting combo context windows).
+const EXPECTED_MODELS = [
+  "gpt-6-astra",
+  "gpt-6-sol",
+  "gpt-6-luna",
+  "gpt-5.6",
+  "gpt-5.6-sol",
+  "gpt-5.6-terra",
+  "gpt-5.6-luna",
+];
 
-test("OpenAI API catalog puts Astra before GPT-5.6 and keeps GPT-5.4", () => {
+// #15023: gpt-6-sol and gpt-6-luna were absent from the OpenAI registry; imported
+// instances fell back to defaultContextLength (128k). These must now appear with the
+// correct 1,050,000 context window, matching the rest of the GPT-6 / GPT-5.6 family.
+const GPT6_SIBLINGS = ["gpt-6-sol", "gpt-6-luna"] as const;
+
+test("OpenAI API catalog exposes gpt-6-sol and gpt-6-luna with 1050000 context (#15023)", () => {
+  const models = getModelsByProviderId("openai");
+
+  for (const modelId of GPT6_SIBLINGS) {
+    const model = models.find((entry) => entry.id === modelId);
+    assert.ok(model, `openai registry must include ${modelId} (was missing — fell back to 128k)`);
+    assert.equal(
+      model!.contextLength,
+      1050000,
+      `${modelId} contextLength must be 1050000, not the 128k import fallback`
+    );
+    assert.equal(model!.maxInputTokens, 922000, `${modelId} maxInputTokens`);
+    assert.equal(model!.maxOutputTokens, 128000, `${modelId} maxOutputTokens`);
+    assert.equal(model!.toolCalling, true, `${modelId} toolCalling`);
+    assert.equal(model!.supportsReasoning, true, `${modelId} supportsReasoning`);
+    assert.equal(model!.supportsVision, true, `${modelId} supportsVision`);
+
+    const spec = getModelSpec(modelId);
+    assert.ok(spec, `MODEL_SPECS must include ${modelId}`);
+    assert.equal(spec!.contextWindow, 1050000, `${modelId} spec contextWindow`);
+    assert.equal(spec!.maxOutputTokens, 128000, `${modelId} spec maxOutputTokens`);
+  }
+});
+
+test("OpenAI API catalog puts Astra/Sol/Luna before GPT-5.6 family and keeps GPT-5.4", () => {
   const models = getModelsByProviderId("openai");
 
   assert.deepEqual(