feat: 诊断（任务书 18 第一块）：诊断数学、四种提交、一次运行跑多个实验、账本与材料、flow 诊断各步

消融默认关，关掉时解释阶段一并跳过；选诊断实验用信息价值减成本。
eval/diagnosis/research.json 为第三块配置。vocab 字段说明的出口文字随提示词一起改，见下一次提交的 prompts/ 与同文件改动（本次含在内）。

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/flow/loop.ts

@@ -1,7 +1,7 @@
 import { mkdirSync } from "node:fs";
 import { resolve } from "node:path";
 import type { ResearchConfig } from "../config/index.ts";
-import { forwardNotRunEvent, cellNotRunEvent } from "../materials/index.ts";
+import { cellNotRunEvent, diagnosisNotRunEvent, forwardNotRunEvent } from "../materials/index.ts";
 import { Ledger } from "../ledger/index.ts";
 import { Runner } from "../runner/index.ts";
 import { fullConfig, readFrozen } from "./frozen.ts";
@@ -10,6 +10,7 @@ import { ledgerFile } from "./paths.ts";
 import { recover } from "./recover.ts";
 import { baselineRun, saveBaseline } from "./steps/baseline.ts";
 import { ablationRun, selectCells, settle, unsealChosen } from "./steps/ablation.ts";
+import { diagnosisDedupe, diagnosisRun, diagnosisSettle, selectDiagnosisExperiments } from "./steps/diagnosis.ts";
 import { forwardRun, adoptBatch } from "./steps/forward.ts";
 import { dispatchStage } from "./steps/dispatch.ts";
 import { dedupe, freezeProtocols, selectBatch } from "./steps/round.ts";
@@ -80,10 +81,12 @@ async function doStep(s: Study, next: Exclude<Next, { do: "freezeConfig" }>): Pr
       return null;
     case "baselineRun":
     case "forwardRun":
-    case "ablationRun": {
+    case "ablationRun":
+    case "diagnosisRun": {
       const ran =
         next.do === "baselineRun" ? await baselineRun(s, next.run)
         : next.do === "forwardRun" ? await forwardRun(s, next.round, next.candidate, next.run)
+        : next.do === "diagnosisRun" ? await diagnosisRun(s, next.round, next.run)
         : await ablationRun(s, next.round, next.cell, next.run);
       if (ran === "stopped") return USER_STOPPED;
       if (ran === "done") return null;
@@ -103,6 +106,18 @@ async function doStep(s: Study, next: Exclude<Next, { do: "freezeConfig" }>): Pr
     case "assignEntries":
       assignEntries(s);
       return null;
+    case "diagnosisDedupe":
+      await diagnosisDedupe(s, next.round);
+      return null;
+    case "selectDiagnosis":
+      selectDiagnosisExperiments(s, next.round);
+      return null;
+    case "diagnosisNotRun":
+      s.ledger.append("event", diagnosisNotRunEvent(next.round, next.reason));
+      return null;
+    case "diagnosisSettle":
+      await diagnosisSettle(s, next.round);
+      return null;
     case "dedupe":
       await dedupe(s, next.round);
       return null;