Resolve compaction policy per routed model

packages/llm/llm-pi-ai/README.md

@@ -28,7 +28,7 @@ Configure credentials and deployment-specific transport settings per provider. O
 
 Each provider name must exist in pi-ai's installed catalog and may appear only once in this plugin instance. Registration with `ctx.llm` is atomic: a collision with any provider route already owned by another adapter fails plugin loading without registering the remaining routes. Model ids are not lifecycle config; an unknown model fails before any provider request with `LlmError('UNKNOWN_MODEL')`.
 
-The adapter exposes each configured provider's installed pi-ai models through `ctx.llm.listModels(provider)`. This is provider-neutral selector metadata derived from `getModels(provider)`; request-time resolution still performs the authoritative catalog lookup, so discovery does not create a second model registry.
+The adapter exposes each configured provider's installed pi-ai models through `ctx.llm.listModels(provider)`. This is provider-neutral selector metadata derived from `getModels(provider)`; request-time resolution still performs the authoritative catalog lookup, so discovery does not create a second model registry. `ctx.llm.resolveModelContext(provider, model)` performs the same exact descriptor lookup and returns its context window, keeping capacity metadata on the route-owning adapter rather than a consuming plugin.
 
 Supported profile fields are `provider`, `apiKey`, `baseURL`, `headers`, `reasoning`, `thinkingBudgets`, `cacheRetention`, `transport`, `timeoutMs`, `websocketConnectTimeoutMs`, `maxRetries`, and `maxRetryDelayMs`. They map to pi-ai's common stream options. Harness app attribution wins a conflicting configured header name.
 

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

@@ -15,7 +15,7 @@ import type {
   SimpleStreamOptions,
 } from '@earendil-works/pi-ai'
 import { attributionHeaders, LlmAdapter, LlmError } from '@deepseek-ai/dsh-llm'
-import type { GenerateOptions, LlmModelInfo, StreamChunk } from '@deepseek-ai/dsh-llm'
+import type { GenerateOptions, LlmModelContext, LlmModelInfo, StreamChunk } from '@deepseek-ai/dsh-llm'
 import type { PiAiProviderProfile } from './config.ts'
 import { toPiContext } from './context.ts'
 import { toStreamChunks } from './stream.ts'
@@ -87,6 +87,22 @@ export class PiAiAdapter extends LlmAdapter {
     })))
   }
 
+  override resolveModelContext(
+    provider: string,
+    model: string,
+  ): Promise<LlmModelContext | undefined> {
+    const profile = this.profiles.get(provider)
+    if (profile === undefined) {
+      return Promise.reject(new LlmError(
+        `pi-ai adapter does not own provider "${provider}"`,
+        'NO_ADAPTER',
+      ))
+    }
+    return Promise.resolve().then(() => ({
+      contextWindow: resolveModel(profile, model).contextWindow,
+    }))
+  }
+
   async * stream(options: GenerateOptions): AsyncIterable<StreamChunk> {
     if (options.stop !== undefined) {
       throw new LlmError('llm-pi-ai does not support GenerateOptions.stop', 'UNSUPPORTED_OPTION')

packages/llm/llm-pi-ai/tests/adapter.spec.ts

@@ -260,6 +260,9 @@ describe('provider profile lifecycle', () => {
       provider: 'openai', id: 'gpt-4.1', name: 'GPT-4.1',
     })
     expect(models.every(model => model.provider === 'openai')).toBe(true)
+    const context = await ctx.llm.resolveModelContext('openai', 'gpt-4.1')
+    expect(context).toBeDefined()
+    expect(typeof context?.contextWindow).toBe('number')
   })
 
   it('accepts absent credentials for pi-ai ambient authentication', async () => {
@@ -296,6 +299,10 @@ describe('provider profile lifecycle', () => {
   it('constructs the adapter directly and rejects routes it does not own', async () => {
     const adapter = new PiAiAdapter({ profiles: [{ provider: 'openai' }] })
     await expect(adapter.listModels('anthropic')).rejects.toMatchObject({ code: 'NO_ADAPTER' })
+    await expect(adapter.resolveModelContext('anthropic', 'claude-sonnet-4'))
+      .rejects.toMatchObject({ code: 'NO_ADAPTER' })
+    await expect(adapter.resolveModelContext('openai', 'not-a-catalog-model'))
+      .rejects.toMatchObject({ code: 'UNKNOWN_MODEL' })
     await expect((async () => {
       for await (const _chunk of adapter.stream({ provider: 'anthropic', model: 'claude-sonnet-4', messages: [] })) { /* drain */ }
     })()).rejects.toMatchObject({ code: 'NO_ADAPTER' })