Implement mandatory app-attribution headers per the RFC

dsh-llm owns the vocabulary (attribution.ts): AppIdentity with the version
read from the package manifest, userAgent(), and attributionHeaders(target,
identity) over a closed AttributionTarget union ('generic' | 'openrouter').
Both adapters send the headers on every provider request — llm-deepseek in
its fetch headers, llm-pi-ai through pi-ai's StreamOptions.headers — behind
an explicit attributionTarget config (never inferred from baseURL), with
mock-server tests asserting exact wire arrival and the absence of the
OpenRouter set by default.

The RFC moves to implemented/ amended with the settled identity (the
deepseek-harness token, the DeepSeek Harness title, the planned
deepseek-ai/deepseek-harness-sdk URL behind a FIXME until that repo exists)
and the explicit-config OpenRouter decision.

packages/llm/llm-pi-ai/src/adapter.ts

@@ -13,9 +13,9 @@
 
 import { stream as piStream } from '@earendil-works/pi-ai'
 import type { Model } from '@earendil-works/pi-ai'
-import { LlmAdapter, LlmError } from '@deepseek-ai/dsh-llm'
+import { attributionHeaders, LlmAdapter, LlmError } from '@deepseek-ai/dsh-llm'
 import { CallId } from '@deepseek-ai/dsh-llm'
-import type { GenerateOptions, StreamChunk, ToolSchema } from '@deepseek-ai/dsh-llm'
+import type { AttributionTarget, GenerateOptions, StreamChunk, ToolSchema } from '@deepseek-ai/dsh-llm'
 import { toPiContext, toStreamChunks } from './convert.ts'
 
 /** Reasoning levels surfaced by this adapter (DeepSeek wire: high|max). */
@@ -26,6 +26,12 @@ export interface PiAiAdapterOptions {
   baseURL: string
   /** Thinking level applied to every request ('off' disables thinking). */
   reasoning?: PiAiReasoning | undefined
+  /**
+   * Provider-specific attribution set on top of the mandatory `User-Agent`
+   * baseline (dsh-llm's `attributionHeaders`). Set to `'openrouter'` when
+   * `baseURL` points at OpenRouter; never inferred from the URL.
+   */
+  attributionTarget?: AttributionTarget | undefined
 }
 
 /** Build the inline pi-ai model descriptor for one DeepSeek model name. */
@@ -171,6 +177,9 @@ export class PiAiAdapter extends LlmAdapter {
     try {
       const events = piStream(model, toPiContext(options), {
         apiKey: this.options.apiKey,
+        // pi-ai merges caller headers last over its provider defaults, so the
+        // harness attribution always reaches the wire.
+        headers: attributionHeaders(this.options.attributionTarget),
         ...options.temperature !== undefined ? { temperature: options.temperature } : {},
         ...options.maxTokens !== undefined ? { maxTokens: options.maxTokens } : {},
         signal: controller.signal,

packages/llm/llm-pi-ai/src/index.ts

@@ -42,6 +42,12 @@ export interface Config {
    * (thinking enabled), matching llm-deepseek's omission semantics.
    */
   reasoning?: PiAiReasoning
+  /**
+   * Provider-specific attribution set to send alongside the mandatory
+   * `User-Agent`: `'openrouter'` when `baseURL` points at OpenRouter.
+   * Omitted = the provider-neutral baseline.
+   */
+  attributionTarget?: 'generic' | 'openrouter'
 }
 
 export const Config: z<Config> = z.object({
@@ -49,6 +55,7 @@ export const Config: z<Config> = z.object({
   baseURL: z.string(),
   models: z.array(z.string()).default(['deepseek-v4-flash', 'deepseek-v4-pro']),
   reasoning: z.union(['off', 'high', 'xhigh']),
+  attributionTarget: z.union(['generic', 'openrouter']),
 })
 
 /** Public API default; the internal endpoint comes from $DEEPSEEK_BASE_URL. */
@@ -67,5 +74,6 @@ export function apply(ctx: Context, config: Config): void {
     apiKey,
     baseURL,
     reasoning: config.reasoning,
+    attributionTarget: config.attributionTarget,
   }))
 }