feat(context): promote MCP compactor to active locally

Add active-mode probe script and document mixed shadow/active promotion;
first active switch is MEMIND_MCP_COMPACT_MODE only.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/context-runtime-local-dev.md

@@ -24,6 +24,21 @@ MEMIND_ZVEC_WORKSPACE_MODE=shadow
 HEADROOM_OUTPUT_SHAPER=0
 ```
 
+**混合晋升（逐项 active）**：shadow 证据足够后，每次只改一个开关，例如：
+
+```bash
+MEMIND_MCP_COMPACT_MODE=active   # 其余保持 shadow
+```
+
+验证：
+
+```bash
+node scripts/check-mcp-compactor-local.mjs
+node scripts/check-mcp-compact-active-local.mjs
+```
+
+active 时 `tkmind-search` / `tkmind-excel` MCP 会暴露 `ctx_fetch`，大 payload 会被压缩为 handle。
+
 Bundle 常量见 `context-runtime-profile.mjs` → `CONTEXT_RUNTIME_SHADOW_ENV`。
 
 ## 离线事件形状预览
@@ -56,6 +71,7 @@ node scripts/check-zvec-workspace-local.mjs
 
 # MCP compactor shadow/active 逻辑
 node scripts/check-mcp-compactor-local.mjs
+node scripts/check-mcp-compact-active-local.mjs
 
 # codebase-memory-mcp CLI + Memind 索引（见 docs/codebase-memory-mcp-local.md）
 node scripts/check-codebase-memory-mcp-local.mjs