fix(replan): compare expected gains with full marginal cost

docs/reference/protocols/goal-vision-replan-contract-v0.md

@@ -288,11 +288,12 @@ instructions through full/compact quota and the host Turn envelope:
   rules; reconsider the latter when they obstruct the goal. This cannot relax
   frozen acceptance, authority, budgets or stops, or rewrite criteria after a
   failure.
-- Before expanding repeated validation, verify that the changed intervention
-  reaches the executed path and current artifact. Prefer a discriminating probe,
-  keep negative evidence scoped to tested conditions and proxies scoped to their
-  coverage, and reuse still-applicable evidence when no new uncertainty warrants
-  repetition.
+- Compare expected progress toward the goal or information gain with the full
+  marginal cost of the next step. Before expanding repeated validation, verify
+  that the changed intervention reaches the executed path and current artifact.
+  Prefer a discriminating probe, keep negative evidence scoped to tested
+  conditions and proxies scoped to their coverage, and reuse still-applicable
+  evidence when no new uncertainty warrants repetition.
 
 This guidance is included by default whenever a replan action packet is
 projected. It is Agent judgment guidance, not a new machine-enforced acceptance
@@ -314,9 +315,10 @@ Turn envelope 中保留：
 - 保留用户要求的优先级和优化方向，区分硬约束与 Agent 暂定的候选筛选规则；
   后者阻碍目标时应重新审视。不能放宽冻结验收、权限、预算或停止条件，
   也不能因失败而事后改写标准。
-- 扩大重复验证前，确认改动进入实际执行路径和当前产物。优先选择能区分剩余
-  解释的探针；负证据只覆盖已测条件，局部代理指标只覆盖其代表的范围。
-  没有新不确定性时复用仍然适用的证据。
+- 将预期的目标推进或信息收益与下一步的完整边际成本一起比较。扩大重复验证前，
+  确认改动进入实际执行路径和当前产物。优先选择能区分剩余解释的探针；负证据
+  只覆盖已测条件，局部代理指标只覆盖其代表的范围。没有新不确定性时复用
+  仍然适用的证据。
 
 这是 Agent 判断指引，不新增机器验收门禁、配置或权限，不改变已有语义写回
 规则及非重规划 Turn。文本复用既有 TypeScript owner；投影测试证明送达和

loopx/control_plane/work_items/replan_semantics.ts

@@ -42,7 +42,8 @@ const REPLAN_PLANNING_GUIDANCE = [
     "and hard constraints from provisional agent-created candidate rules; revisit the latter " +
     "when they obstruct the goal. Do not relax frozen acceptance, authority, budget or stops, " +
     "or rewrite criteria after failure.",
-  "Before widening repeated validation, check that the changed intervention reaches the " +
+  "Compare expected goal/information gain with full marginal cost. " +
+    "Before widening repeated validation, check that the changed intervention reaches the " +
     "executed path and current artifact. Prefer a probe that distinguishes remaining explanations; " +
     "scope negative results to tested conditions and local proxies to their coverage. " +
     "Reuse still-applicable evidence instead of repeating checks without a new uncertainty.",

tests/control_plane/test_replan_host_context_projection.py

@@ -233,6 +233,7 @@ def test_replan_guidance_survives_cli_and_host_compaction_without_new_authority(
     assert "provisional agent-created candidate rules" in guidance[3]
     assert "Do not relax frozen acceptance, authority, budget or stops" in guidance[3]
     assert "or rewrite criteria after failure" in guidance[3]
+    assert "Compare expected goal/information gain with full marginal cost" in guidance[4]
     assert "executed path and current artifact" in guidance[4]
     assert "probe that distinguishes remaining explanations" in guidance[4]
     assert "scope negative results to tested conditions and local proxies to their coverage" in guidance[4]

tests/control_plane_ts/replan_semantics.test.ts

@@ -298,6 +298,7 @@ test("planning advice cannot discharge a replan or widen source-specific exits",
     assert.equal(guidance.length, 5);
     assert.match(guidance[3], /provisional agent-created candidate rules/);
     assert.match(guidance[3], /Do not relax frozen acceptance/);
+    assert.match(guidance[4], /Compare expected goal\/information gain with full marginal cost/);
     assert.match(guidance[4], /executed path and current artifact/);
     assert.match(guidance[4], /scope negative results to tested conditions/);
     const refusal = projectReplanSemantics({operation: "qualify", obligation: source,