test(quality): promote routing coverage to core gate

docs/EXECUTION_BOARD.md

@@ -1967,3 +1967,56 @@
   - `internal/routing`
   - `internal/store/sqlite`
   - `internal/overlay`
+
+## 2026-05-30 已将 internal/routing 从 watch 提升为 core
+
+**目标**：把 `logical_group -> route -> sticky -> failover -> cooldown -> route log` 这条高杠杆运行时链路纳入硬门槛，避免只作为显式观察项放行回归
+
+**评估结果**：
+
+- `go test -coverprofile=/tmp/internal-routing.cover ./internal/routing` => `coverage: 73.1% of statements`
+- 现有测试覆盖面已包含：
+  - `sticky key` 构造
+  - `memory sticky store`
+  - `redis sticky store` round-trip
+  - `failure / cooldown` 状态
+  - `async log writer` append / flush / close
+- 当前低覆盖点主要集中在：
+  - `sticky_redis.go`
+    - `ClearRouteFailure`
+    - `ClearCooldown`
+  - `logwriter.go`
+    - `Flush`
+    - `loop`
+- 这些缺口已记录，但不影响把该包提升为 `core`，因为包级覆盖率已稳定高于硬门槛，且核心行为已被真实测试覆盖
+
+**本次调整**：
+
+- `tests/quality/coverage_thresholds.tsv`
+  - `internal/routing`
+    - tier：`watch -> core`
+    - threshold：`70.0` 保持不变
+
+**验证结果**：
+
+- `gofmt -l .` => clean
+- `go vet ./...` => `ok`
+- `go test -cover ./internal/...` => `ok`
+- `go test ./tests/integration/... -count=1` => `ok`
+- `bash ./scripts/test/verify_quality_gates.sh` => `PASS`
+- 统一门禁回读：
+  - `internal/routing = 73.1%`
+  - 高于新的 `core` 门槛 `70.0%`
+
+**结论**：
+
+- `internal/routing` 已完成第二批 `watch -> core` 升级
+- 当前 `core` 包集合变为：
+  - `internal/access`
+  - `internal/pack`
+  - `internal/provision`
+  - `internal/app`
+  - `internal/routing`
+- 下一批候选可继续看：
+  - `internal/store/sqlite`
+  - `internal/overlay`

tests/quality/coverage_thresholds.tsv

@@ -4,5 +4,5 @@ internal/pack	core	70.0	pack loading and validation
 internal/provision	core	70.0	provider import orchestration
 internal/app	core	70.0	HTTP control plane is now above 70 and must stay as a hard gate
 internal/overlay	watch	70.0	utility package should stay above a healthy baseline
-internal/routing	watch	70.0	route resolve and sticky runtime should not regress
+internal/routing	core	70.0	route resolve and sticky runtime are product-critical and must stay above the hard gate
 internal/store/sqlite	watch	75.0	sqlite repo layer is high leverage and should stay well-covered