fix(providers): preserved llama train context fallback

Kept llama.cpp n_ctx_train as a bounded fallback only after runtime n_ctx and server props are unavailable.

packages/coding-agent/src/config/model-discovery.ts

@@ -126,7 +126,8 @@ type LlamaCppDiscoveredServerMetadata = {
 
 type LlamaCppModelListEntry = {
 	id: string;
-	contextWindow?: number;
+	runtimeContextWindow?: number;
+	trainingContextWindow?: number;
 };
 
 function toPositiveNumberOrUndefined(value: unknown): number | undefined {
@@ -183,12 +184,17 @@ function extractLlamaCppContextWindow(payload: Record<string, unknown>): number
 	return toPositiveNumberOrUndefined(payload.n_ctx);
 }
 
-function extractLlamaCppModelContextWindow(item: Record<string, unknown>): number | undefined {
+function extractLlamaCppModelContextWindows(
+	item: Record<string, unknown>,
+): Pick<LlamaCppModelListEntry, "runtimeContextWindow" | "trainingContextWindow"> {
 	const meta = item.meta;
 	if (!isRecord(meta)) {
-		return undefined;
+		return {};
 	}
-	return toPositiveNumberOrUndefined(meta.n_ctx);
+	return {
+		runtimeContextWindow: toPositiveNumberOrUndefined(meta.n_ctx),
+		trainingContextWindow: toPositiveNumberOrUndefined(meta.n_ctx_train),
+	};
 }
 
 function parseLlamaCppModelList(payload: unknown): LlamaCppModelListEntry[] {
@@ -199,7 +205,7 @@ function parseLlamaCppModelList(payload: unknown): LlamaCppModelListEntry[] {
 		if (!isRecord(item) || typeof item.id !== "string" || !item.id) {
 			return [];
 		}
-		return [{ id: item.id, contextWindow: extractLlamaCppModelContextWindow(item) }];
+		return [{ id: item.id, ...extractLlamaCppModelContextWindows(item) }];
 	});
 }
 
@@ -387,7 +393,11 @@ export async function discoverLlamaCppModels(
 	for (const item of models) {
 		const { id } = item;
 		if (!id) continue;
-		const contextWindow = item.contextWindow ?? serverMetadata?.contextWindow ?? DISCOVERY_DEFAULT_CONTEXT_WINDOW;
+		const contextWindow =
+			item.runtimeContextWindow ??
+			serverMetadata?.contextWindow ??
+			item.trainingContextWindow ??
+			DISCOVERY_DEFAULT_CONTEXT_WINDOW;
 		discovered.push(
 			buildModel({
 				id,
@@ -429,7 +439,8 @@ export async function discoverLlamaCppModelContextWindow(
 			return undefined;
 		}
 		const entries = parseLlamaCppModelList(await response.json());
-		return entries.find(entry => entry.id === model.id)?.contextWindow;
+		const entry = entries.find(entry => entry.id === model.id);
+		return entry?.runtimeContextWindow ?? entry?.trainingContextWindow;
 	};
 	try {
 		const apiKey = await ctx.getBearerApiKeyResolver(model.provider);

packages/coding-agent/test/model-discovery.test.ts

@@ -716,6 +716,31 @@ describe("ModelRegistry runtime discovery", () => {
 		expect(registry.find("llama.cpp", "unloaded")?.contextWindow).toBe(128000);
 	});
 
+	test("llama.cpp discovery falls back to n_ctx_train before the global default", async () => {
+		const fetchMock: FetchImpl = async input => {
+			const url = String(input);
+			if (url === "http://127.0.0.1:8080/models") {
+				return new Response(
+					JSON.stringify({
+						data: [{ id: "ctx-train", meta: { n_ctx_train: 65536 } }, { id: "unloaded" }],
+					}),
+					{ status: 200, headers: { "Content-Type": "application/json" } },
+				);
+			}
+			if (url === "http://127.0.0.1:8080/props") {
+				return new Response(JSON.stringify({ default_generation_settings: {} }), {
+					status: 200,
+					headers: { "Content-Type": "application/json" },
+				});
+			}
+			throw new Error(`Unexpected URL: ${url}`);
+		};
+		const registry = new ModelRegistry(authStorage, modelsJsonPath, { fetch: fetchMock });
+		await registry.refresh();
+		expect(registry.find("llama.cpp", "ctx-train")?.contextWindow).toBe(65536);
+		expect(registry.find("llama.cpp", "unloaded")?.contextWindow).toBe(128000);
+	});
+
 	test("llama.cpp selected model refresh patches newly loaded meta n_ctx", async () => {
 		writeModelCache(
 			"llama.cpp",