Fix review issues #11-#16: StreamK fixpipe 单次计账 / K=1 AIV单缓冲方案 / MergeBatch b0 L0A/L0B 上限+路由可行回退 / advice-StreamK / 输入校验 / .gitignore+死代码清理

BMM/BMM_Theory/bmm_theory/router.py

@@ -78,11 +78,9 @@ class BranchRouter:
         mb = self.merge_batch.analyze(case)
         ib = self.iter_batch.analyze(case)
 
-        candidates = []
-        if mb.capable:
-            candidates.append((self.merge_batch.name, mb))
-        if ib.capable:
-            candidates.append((self.iter_batch.name, ib))
+        # 候选表: [(分支名, BranchResult)], 顺序 = 仲裁优先级
+        cand_map = {self.merge_batch.name: mb, self.iter_batch.name: ib}
+        capable = {n: r.capable for n, r in cand_map.items()}
 
         arbitration = ""
         if mb.capable and ib.capable:
@@ -100,8 +98,8 @@ class BranchRouter:
             )
             if win != lat_win:
                 win = lat_win  # 时延模型为最终裁决
-        elif candidates:
-            win = candidates[0][0]
+        elif any(capable.values()):
+            win = next(n for n, v in capable.items() if v)
             arbitration = f"仅 {win} 条件满足"
         else:
             # 切B分支都不满足, 尝试 StreamK 再回落 ASW
@@ -115,11 +113,37 @@ class BranchRouter:
                 f"IterBatch未过: {ib.failed_conditions()}; "
                 f"MergeBatch未过: {mb.failed_conditions()}")
 
-        chosen = mb if win == self.merge_batch.name else ib
+        # 可行性保障 (issue#13): 仲裁胜出方案必须通过约束自检, 否则按
+        # (另一切B候选 -> StreamK -> ASW_Basic) 顺序回退到首个可行方案.
+        from .constraints import check_plan_constraints
+
+        def _feasible(n):
+            r = cand_map[n]
+            return r.plan is not None and not check_plan_constraints(case, r.plan, self.spec)
+
+        if _feasible(win):
+            chosen = cand_map[win]
+        else:
+            loser = self.merge_batch.name if win == self.iter_batch.name else self.iter_batch.name
+            fallback_note = (f"; 但 {win} 方案自检违规: "
+                             f"{'; '.join(check_plan_constraints(case, cand_map[win].plan, self.spec))}")
+            if capable.get(loser) and _feasible(loser):
+                chosen, win = cand_map[loser], loser
+                fallback_note += f", 回退可行候选 {loser}"
+            else:
+                sk = self.stream_k.analyze(case)
+                if sk.capable and sk.plan is not None and \
+                        not check_plan_constraints(case, sk.plan, self.spec):
+                    return self._wrap_checked(case, sk, arbitration + fallback_note + ", 落 StreamK")
+                asw = self.asw_basic.analyze(case)
+                if asw.plan is not None and not check_plan_constraints(case, asw.plan, self.spec):
+                    return self._wrap_checked(case, asw, arbitration + fallback_note + ", 回落 ASW_Basic")
+                chosen, win = cand_map[win], win  # 无可行方案: 保留原裁决, 由自检标注
+            arbitration += fallback_note
+
         result = BranchResult(capable=True, plan=chosen.plan, timing=chosen.timing)
         return self._wrap_checked(case, result, arbitration,
-                                  candidates={n: r.capable for n, r in
-                                              [(self.merge_batch.name, mb), (self.iter_batch.name, ib)]})
+                                  candidates=capable)
 
     # ------------------------------------------------------------------
     def _wrap_checked(self, case: BmmCase, result: BranchResult, note: str,
@@ -155,15 +179,3 @@ class BranchRouter:
         return {"branch": branch, "plan": plan, "timing": None,
                 "arbitration": "[无方案] " + note, "candidates": {},
                 "self_check_violations": []}
-
-    # ------------------------------------------------------------------
-    @staticmethod
-    def _wrap(result: BranchResult, note: str) -> dict:
-        return {
-            "branch": result.plan.branch if result.plan else "未知",
-            "plan": result.plan,
-            "timing": result.timing,
-            "arbitration": note + (f" | {result.note}" if result.note else ""),
-            "candidates": {},
-            "self_check_violations": [],
-        }