fix(consult): BUG-950~953 Pass 4 按句放行，无分钟按句丢弃

正文不再整段 hold：闭合句立刻过 Pass 4，无 reject 即发（950）。
无出生分钟改为按句丢弃，全丢才用兜底句（951）；该模式日期记 observe（952）。
校正流 token 级 thinking 死链按 P2 删除，测试翻转成否定合同（953）。

frontend/tests/rectification-step-answer.test.ts

@@ -1,4 +1,5 @@
 import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
 import test from "node:test";
 
 import {
@@ -7,8 +8,7 @@ import {
   flushStepAnswerOnStreamFinish,
   shouldPublishStepText,
 } from "../src/lib/rectification-agentic/v9/step-answer.ts";
-import { mapStreamChunkToPhase, mapStreamChunkToThinking } from "../src/lib/rectification-agentic/v9/stream-mapping.ts";
-import { createThinkingFragmentAssembler } from "../src/lib/think-step-gate.ts";
+import { mapStreamChunkToPhase } from "../src/lib/rectification-agentic/v9/stream-mapping.ts";
 import { PUBLIC_RECTIFICATION_TOOLS } from "../src/lib/rectification-agentic/v9/public-receipt.ts";
 
 function isPublicTool(name: string): boolean {
@@ -40,16 +40,29 @@ test("does not publish intermediate tool-step text as answer.delta", () => {
 });
 
 test("never publishes reasoning-delta to the browser", () => {
+  // 原值：mapStreamChunkToThinking 把中文 reasoning 变成 thinking.delta
+  // 新值：校正流对 reasoning-delta 必须丢弃；源码不得把它映射成对外事件
+  // 原因：BUG-953，token 级 thinking 是死链且违反 P2（provider reasoning 永不外发）
   assert.equal(mapStreamChunkToPhase(chunk("reasoning-delta", { text: "Let me" }) as never), null);
   assert.equal(mapStreamChunkToPhase(chunk("text-delta", { text: "Let me" }) as never), null);
-  assert.ok(mapStreamChunkToThinking(chunk("reasoning-delta", { text: "先核对经历。" }) as never));
+  const state = createStepAnswerState();
+  assert.equal(
+    applyStepAnswerChunk(state, chunk("reasoning-delta", { text: "先核对经历。" }), isPublicTool).kind,
+    "none",
+  );
+  const mapping = readFileSync(new URL("../src/lib/rectification-agentic/v9/stream-mapping.ts", import.meta.url), "utf8");
+  assert.doesNotMatch(mapping, /function mapStreamChunkToThinking|function toPublicThinkingDelta|InternalThinkingDeltaEvent/);
 });
 
 test("consecutive Chinese reasoning fragments assemble into a visible thinking line", () => {
-  const assembler = createThinkingFragmentAssembler();
-  assert.equal(assembler.push("The proposedKind value was rejected"), null);
-  assert.equal(assembler.push("先核"), null);
-  assert.equal(assembler.push("对经历。"), "先核对经历。");
+  // 原值：createThinkingFragmentAssembler 把「先核」+「对经历。」拼成可见思考行
+  // 新值：分片组装器删除；连续 reasoning-delta 仍全部丢弃
+  // 原因：BUG-953，翻转成否定合同，测试总数不降
+  const state = createStepAnswerState();
+  assert.equal(applyStepAnswerChunk(state, chunk("reasoning-delta", { text: "先核" }), isPublicTool).kind, "none");
+  assert.equal(applyStepAnswerChunk(state, chunk("reasoning-delta", { text: "对经历。" }), isPublicTool).kind, "none");
+  const gate = readFileSync(new URL("../src/lib/think-step-gate.ts", import.meta.url), "utf8");
+  assert.doesNotMatch(gate, /acceptThinkingFragment|createThinkingFragmentAssembler/);
 });
 
 test("publishes only the terminal no-tool step as assistant text", () => {