docs: document orchestrator cost budget and refresh cost example model (#361)

- README_zh.md: add the "Cap estimated cost" section and production-checklist
  row that #358 added only to the English package README, keeping EN/ZH in sync
- consensus.md: extend the budget invariant so maxCostBudget is documented at
  the same verify-hook boundary as maxTokenBudget; standalone runConsensus
  tracks tokens only
- README EN/ZH: switch the cost example to gpt-5.4-mini, pricing matching the
  repo's existing cost-tiered-pipeline example

Follow-up documentation for #358.

docs/consensus.md

@@ -56,7 +56,7 @@ After the task completes, its result is fed into the same consensus loop. If con
 
 ## Budget invariant
 
-Consensus token usage counts against the parent budget exactly like delegation does. Proposer, judge, and revision usage all accumulate into the running total and are checked against `OrchestratorConfig.maxTokenBudget`. Once the cumulative total crosses the budget, consensus **stops issuing further judge calls** — no separate budget knob, no escape hatch. For the per-task `verify` hook, judge usage rolls into the same run-level budget as the rest of the pipeline and trips the same gate.
+Consensus token usage counts against the parent budget exactly like delegation does. Proposer, judge, and revision usage all accumulate into the running total and are checked against `OrchestratorConfig.maxTokenBudget`. Once the cumulative total crosses the budget, consensus **stops issuing further judge calls** — no separate budget knob, no escape hatch. For the per-task `verify` hook, judge usage rolls into the same run-level budget as the rest of the pipeline and trips the same gate. The same holds for cost: when `estimateCost` and `maxCostBudget` are configured, verify-hook usage is priced into the run's cumulative estimated cost and stops further judge calls at the same boundary once the cap is crossed. Because `maxCostBudget` is a run-level cap, the standalone `runConsensus` primitive tracks tokens only.
 
 ## Observability
 

packages/core/README.md

@@ -198,7 +198,7 @@ const orchestrator = new OpenMultiAgent({
 
 ```ts
 const prices = {
-  'gpt-4.1-mini': { input: 0.40, output: 1.60 }, // USD per 1M tokens
+  'gpt-5.4-mini': { input: 0.75, output: 4.5 }, // USD per 1M tokens
 }
 
 const orchestrator = new OpenMultiAgent({

packages/core/README_zh.md

@@ -194,6 +194,23 @@ const orchestrator = new OpenMultiAgent({
 })
 ```
 
+**封顶预估成本。** 价格表由应用侧维护，并提供估价函数；OMA 会将生效的 `model`、`provider`、执行阶段与 `taskId`（若有）一并传入，以便按模型计价。成本上限在与 `maxTokenBudget` 相同的轮次/任务边界处校验，单次运行至多可能超出一个模型轮次，并非精确到分的即时中止。
+
+```ts
+const prices = {
+  'gpt-5.4-mini': { input: 0.75, output: 4.5 }, // 美元，每百万 tokens
+}
+
+const orchestrator = new OpenMultiAgent({
+  maxCostBudget: 0.25,
+  estimateCost: (usage, { model }) => {
+    const price = prices[model] ?? { input: 0, output: 0 }
+    return (usage.input_tokens / 1_000_000) * price.input
+      + (usage.output_tokens / 1_000_000) * price.output
+  },
+})
+```
+
 **取消运行。** 传入 `AbortSignal`；触发 abort 即中止运行。
 
 ```ts
@@ -402,7 +419,8 @@ await oma.runAgent(
 | 限制工具输出 | `maxToolOutputChars`（或单工具 `maxOutputChars`）+ `compressToolResults: true` | `AgentConfig` 和 `defineTool()` |
 | 失败重试 | 任务级 `maxRetries`、`retryDelayMs`、`retryBackoff`（指数退避倍率） | 通过 `runTasks()` 用的任务配置 |
 | 崩溃/重启后恢复 | `checkpoint`（给 `runId`，或内置 `FileStore` 等持久化 `MemoryStore`）+ `restore()` 恢复运行，跳过已完成任务 | `OrchestratorConfig` / 运行选项 |
-| 总额封顶 | orchestrator 上设 `maxTokenBudget` | `OrchestratorConfig` |
+| token 用量封顶 | orchestrator 上设 `maxTokenBudget` | `OrchestratorConfig` |
+| 预估成本封顶 | `maxCostBudget` + `estimateCost`；每个模型的价格表由应用侧维护，校验发生在轮次/任务边界，而非精确到分的调用中途中止 | `OrchestratorConfig` |
 | 卡死检测 | `loopDetection` + `onLoopDetected: 'terminate'`（或自定义 handler） | `AgentConfig` |
 | 追踪与审计 | `onTrace` 接你的 tracing 后端；落盘 `renderTeamRunDashboard(result)` | `OrchestratorConfig` |
 | 脱敏密钥 | 自动：API key、token、Authorization header 从 trace、bash 输出、dashboard payload 中剥除 | 内置（默认开启） |