TypeError: adapter.imageRequestPricing is not a function — breaks /compact and auto-compaction for duck-typed plugin adapters

[6555355]

问题描述 / Problem

在 dsh 0.1.2-alpha.2（master 与最新 tag dsh-v0.1.2-alpha.4 同样存在）上，由第三方插件以「鸭子类型」注册 LLM 适配器（普通对象，不带基类可选方法）后，运行 /compact 抛：

TypeError: this.adapters.get(...)?.adapter.imageRequestPricing is not a function

触发插件：@liustack/modlens（dsh/index.js 约 L750 用 llm.registerAdapter([providerId], {providerInfo, providerRetryPolicy, listModels, resolveModel, prepareCall, stream, ...}) 注册，没有 imageRequestPricing——该方法晚于插件诞生）。

影响 / Impact（一个根因，三个症状）

1. 手动 /compact 直接 command/done kind=error 崩溃；
2. 自动压缩静默失效：agent/pre-step 监听器 catch 所有错误后只打 warn step compaction failed: ...; continuing the turn，继续回合——会话一路涨到 ~143K totalTokens（contextWindow 131072）从不压缩；
3. 溢出恢复失败：顶到 CONTEXT_WINDOW_EXCEEDED 后 compactIfNeeded 同样炸，无法压缩，会话被截断。

调用链 / Call chain

/compact → ctx.compaction.compactNow()
→ compaction-basic compactIfNeeded
→ tokenMeter.measure(session)
→ _routeImagePricing(header)            // packages/llm/token-meter/src/index.ts ~L180-184，在 try/catch 之外
→ ctx.get('llm')?.imageRequestPricing(provider, model)
→ packages/llm/llm/src/index.ts L659-661

根因 / Root cause

• LlmRuntime.registerAdapter 存储原始适配器对象，支持鸭子类型注册（prepareRoutes 只校验 providerInfo / providerRetryPolicy）；
• LlmAdapter.imageRequestPricing 是基类可选方法（默认返回 undefined），但鸭子类型对象未继承基类，等于没有该方法；
• 调用点 this.adapters.get(provider)?.adapter.imageRequestPricing(provider, model) 的 ?. 只防「适配器不存在」，不防「方法不存在」→ 直接 TypeError。

与先前同类问题同根：modlens 曾缺失 prepareCall 导致 registration.adapter.prepareCall is not a function（适配器契约演进后，鸭子类型注册的第三方插件未跟上）。

建议修复 / Proposed fix

packages/llm/llm/src/index.ts LlmRuntime.imageRequestPricing（L659）改为方法存在性守卫，语义为「适配器未声明该方法 → 按无图片定价降级」：

imageRequestPricing(provider: string, model: string): LlmImageRequestPricing | undefined {
  const adapter = this.adapters.get(provider)?.adapter
  return typeof adapter?.imageRequestPricing === 'function'
    ? adapter.imageRequestPricing(provider, model)
    : undefined
}

该模式建议推广到 LlmRuntime 上所有「取适配器可选方法」的调用点。

回归测试 / Regression test

packages/llm/llm/tests/topology.spec.ts 的 imageRequestPricing resolution 用例新增鸭子类型分支：注册 ['duck']（普通对象，须带 providerRetryPolicy()，否则先炸在 prepareRoutes），断言 ctx.llm.imageRequestPricing('duck','vision') 为 undefined。

环境 / Environment

• dsh：0.1.2-alpha.2（问题在 master 与 dsh-v0.1.2-alpha.4 复现）
• OS：Windows
• 路由：modlens-deepseekgongsi/deepseek-v4-flash（contextWindow 131072）
• 插件：@liustack/modlens 3.25.3

[argszero]

Verified every claim against 4e84901e64 (dsh 0.1.2-alpha.4) — your analysis is exact, and the fix you propose is correct. One addition: this is a family of call sites, not a single one, so there is a durable fix that covers all of them.

Mechanism confirmed (alpha.4):

• LlmRuntime.imageRequestPricing (:659-660): return this.adapters.get(provider)?.adapter.imageRequestPricing(provider, model) — the ?. guards the map entry only, never the method.
• The base class default (:221) returns undefined ("The default declares none, so consumers fall back to their own neutral estimate") — the runtime method's own JSDoc promises "or undefined when the provider is unregistered or declares none", and the implementation fails that intent for duck-typed adapters.
• prepareRoutes (:424-429) validates only providerInfo + providerRetryPolicy — no method-surface check, so the duck-typed registration sails through.
• token-meter measure() calls _routeImagePricing(header) (:144) outside any try/catch, so the TypeError propagates and kills the whole compaction — matching your three symptoms (manual /compact dies, auto-compaction warns and skips, overflow recovery can't run).

Your proposed guard is right — typeof adapter?.imageRequestPricing === 'function' ? ... : undefined restores exactly the documented semantics.

The family finding: the same unguarded pattern exists at three more runtime sites:

• listModels (:675-676) — this.registration(provider).adapter.listModels(provider)
• prepareCall (:892, and the dispatch path :976) — registration.adapter.prepareCall(...)

registration() throws NO_ADAPTER for unregistered providers, so those sites never see a missing map entry — but they still see a missing method on a duck-typed adapter. Your modlens note is the evidence: it already hit prepareCall is not a function once. Any third-party adapter that omits listModels/prepareCall crashes those paths exactly like imageRequestPricing.

Durable fix option (recommend alongside the one-liner): every LlmAdapter method except stream has a base-class default (imageRequestPricing → undefined, listModels → [], resolveModel → identity, prepareCall → resolveModel+stream wrapper). Since registerAdapter deliberately accepts duck-typed objects, normalize at registration time: wrap the adapter in a per-registration facade that fills missing optional methods from the base defaults (without mutating the caller's object), and optionally fail-fast on a missing stream (the one truly required method). That converts every future contract drift into "declares none" semantics at one seam instead of patching call sites one crash at a time.

Test alignment: llm package unit test — register a duck-typed adapter (no imageRequestPricing/listModels/prepareCall), assert imageRequestPricing returns undefined (and, with the normalization, listModels returns [] and a call still streams) instead of throwing. That locks the contract-drift family shut.

Want me to shape this into a concrete diff for the core, or is your fork already carrying it?