feat(llm): add default context window fallback

packages/llm/llm-deepseek/src/adapter.ts

@@ -40,6 +40,8 @@ export interface DeepSeekAdapterOptions {
   baseURL: string
   /** Request defaults applied to every call (thinking mode, effort). */
   defaults?: RequestDefaults
+  /** Positive context capacity used when the selected model has no exact value. */
+  defaultContextWindow?: number
   /** Advisory models exposed to discovery consumers; requests remain unrestricted. */
   models?: readonly DeepSeekCatalogModel[]
   /** Maximum provider idle time while one stream read is outstanding. */
@@ -96,6 +98,10 @@ export class DeepSeekAdapter extends LlmAdapter {
 
   constructor(private readonly options: DeepSeekAdapterOptions) {
     super()
+    if (options.defaultContextWindow !== undefined
+      && (!Number.isInteger(options.defaultContextWindow) || options.defaultContextWindow <= 0)) {
+      throw new Error('llm-deepseek: defaultContextWindow must be a positive integer')
+    }
     this.streamIdleTimeoutMs = options.streamIdleTimeoutMs ?? DEFAULT_STREAM_IDLE_TIMEOUT_MS
     if (!Number.isFinite(this.streamIdleTimeoutMs)
       || this.streamIdleTimeoutMs <= 0
@@ -124,6 +130,7 @@ export class DeepSeekAdapter extends LlmAdapter {
     model: string,
   ): Promise<LlmModelContext | undefined> {
     const contextWindow = this.options.models?.find(entry => entry.id === model)?.contextWindow
+      ?? this.options.defaultContextWindow
     return Promise.resolve(contextWindow === undefined ? undefined : { contextWindow })
   }
 

packages/llm/llm-deepseek/src/index.ts

@@ -40,6 +40,8 @@ export interface Config {
   thinking?: 'enabled' | 'disabled'
   /** Thinking effort (only meaningful with thinking enabled). */
   reasoningEffort?: 'high' | 'max'
+  /** Positive context capacity used when the selected model has no exact value. */
+  defaultContextWindow?: number
   /** Advisory models shown by discovery consumers; defaults to V4 Flash and V4 Pro. */
   models?: DeepSeekCatalogModel[]
   /** Maximum provider idle time while one stream read is outstanding (default five minutes). */
@@ -58,6 +60,7 @@ export const Config: z<Config> = z.object({
   baseURL: z.string(),
   thinking: z.union(['enabled', 'disabled']),
   reasoningEffort: z.union(['high', 'max']),
+  defaultContextWindow: z.number().step(1).min(1),
   models: z.array(catalogModel).default(DEFAULT_MODELS),
   streamIdleTimeoutMs: z.number().min(Number.MIN_VALUE).max(MAX_TIMER_DELAY_MS).default(DEFAULT_STREAM_IDLE_TIMEOUT_MS),
 })
@@ -103,6 +106,9 @@ export function apply(ctx: Context, config: Config): void {
       thinking: config.thinking,
       reasoningEffort: config.reasoningEffort,
     },
+    ...config.defaultContextWindow === undefined
+      ? {}
+      : { defaultContextWindow: config.defaultContextWindow },
     models: resolveModels(config.models),
     streamIdleTimeoutMs: config.streamIdleTimeoutMs ?? DEFAULT_STREAM_IDLE_TIMEOUT_MS,
   }))