perf(middleware): before_completion 分波并行执行

- MiddlewareContext 加 Clone derive, 支持并行克隆上下文
- AgentMiddleware trait 新增 parallel_safe() 默认方法 (false)
- MiddlewareChain::run_before_completion 改为分波执行:
  连续 2+ 个 parallel_safe 中间件用 tokio::spawn 并发执行,
  各自独立修改 system_prompt, 执行完成后合并贡献
- 5 个只修改 system_prompt 的中间件标记 parallel_safe:
  evolution(P78), butler_router(P80), memory(P150),
  title(P180), skill_index(P200)
- 非 parallel_safe 中间件 (compaction, dangling_tool 等) 保持串行

分波效果:
  Wave 1: evolution + butler_router → 并行 (省 ~0.5-1s)
  Wave 2: compaction → 串行 (可能修改 messages)
  Wave 3: memory + title + skill_index → 并行 (省 ~0.5-2s)
  Wave 4+: 工具/安全中间件 → 串行

crates/zclaw-runtime/src/middleware.rs

@@ -12,6 +12,13 @@
 //! | 200-399 | Capability     | SkillIndex, Guardrail       |
 //! | 400-599 | Safety         | LoopGuard, Guardrail        |
 //! | 600-799 | Telemetry      | TokenCalibration, Tracking  |
+//!
+//! # Wave parallelization
+//!
+//! `before_completion` middlewares that only modify `system_prompt` (not `messages`)
+//! can declare `parallel_safe() == true`. The chain runs consecutive parallel-safe
+//! middlewares concurrently, merging their prompt contributions. This reduces
+//! sequential latency for the context-injection phase.
 
 use std::sync::Arc;
 use async_trait::async_trait;
@@ -50,6 +57,7 @@ pub enum ToolCallDecision {
 // ---------------------------------------------------------------------------
 
 /// Carries the mutable state that middleware may inspect or modify.
+#[derive(Clone)]
 pub struct MiddlewareContext {
     /// The agent that owns this loop.
     pub agent_id: AgentId,
@@ -101,6 +109,15 @@ pub trait AgentMiddleware: Send + Sync {
         500
     }
 
+    /// Whether `before_completion` is safe to run concurrently with other
+    /// parallel-safe middlewares. Only return `true` if the middleware:
+    /// - Only modifies `ctx.system_prompt` (never `ctx.messages`)
+    /// - Does not depend on prompt modifications from other middlewares
+    /// - Does not return `MiddlewareDecision::Stop`
+    fn parallel_safe(&self) -> bool {
+        false
+    }
+
     /// Hook executed **before** the LLM completion request is sent.
     ///
     /// Use this to inject context (memory, skill index, etc.) or to
@@ -163,9 +180,66 @@ impl MiddlewareChain {
         self.middlewares.insert(pos, mw);
     }
 
-    /// Run all `before_completion` hooks in order.
+    /// Run all `before_completion` hooks with wave-based parallelization.
+    ///
+    /// Consecutive `parallel_safe` middlewares run concurrently — each gets
+    /// its own cloned context and appends to `system_prompt` independently.
+    /// Their contributions are merged after all complete. Non-parallel-safe
+    /// middlewares (and non-consecutive ones) run sequentially as before.
     pub async fn run_before_completion(&self, ctx: &mut MiddlewareContext) -> Result<MiddlewareDecision> {
-        for mw in &self.middlewares {
+        let mut idx = 0;
+        while idx < self.middlewares.len() {
+            // Find the extent of consecutive parallel-safe middlewares
+            let wave_start = idx;
+            let mut wave_end = idx;
+            while wave_end < self.middlewares.len()
+                && self.middlewares[wave_end].parallel_safe()
+            {
+                wave_end += 1;
+            }
+
+            if wave_end - wave_start >= 2 {
+                // Run parallel wave (2+ consecutive parallel-safe middlewares)
+                let base_prompt_len = ctx.system_prompt.len();
+                let wave = &self.middlewares[wave_start..wave_end];
+
+                // Spawn concurrent tasks — each owns its cloned context + Arc ref to middleware
+                let mut join_handles = Vec::with_capacity(wave.len());
+                for mw in wave.iter() {
+                    let mut ctx_clone = ctx.clone();
+                    let mw_arc = Arc::clone(mw);
+                    join_handles.push(tokio::spawn(async move {
+                        let result = mw_arc.before_completion(&mut ctx_clone).await;
+                        (result, ctx_clone.system_prompt)
+                    }));
+                }
+
+                // Await all and merge prompt contributions
+                for (i, handle) in join_handles.into_iter().enumerate() {
+                    let (result, modified_prompt): (Result<MiddlewareDecision>, String) = handle.await
+                        .map_err(|e| zclaw_types::ZclawError::Internal(format!("Parallel middleware panicked: {}", e)))?;
+                    match result? {
+                        MiddlewareDecision::Continue => {}
+                        MiddlewareDecision::Stop(reason) => {
+                            tracing::info!(
+                                "[MiddlewareChain] '{}' requested stop: {}",
+                                self.middlewares[wave_start + i].name(),
+                                reason
+                            );
+                            return Ok(MiddlewareDecision::Stop(reason));
+                        }
+                    }
+                    // Merge system_prompt contribution from this clone
+                    if modified_prompt.len() > base_prompt_len {
+                        let contribution = &modified_prompt[base_prompt_len..];
+                        ctx.system_prompt.push_str(contribution);
+                    }
+                }
+
+                idx = wave_end;
+            } else {
+                // Run single middleware sequentially
+                let mw = &self.middlewares[idx];
                 match mw.before_completion(ctx).await? {
                     MiddlewareDecision::Continue => {}
                     MiddlewareDecision::Stop(reason) => {
@@ -173,6 +247,8 @@ impl MiddlewareChain {
                         return Ok(MiddlewareDecision::Stop(reason));
                     }
                 }
+                idx += 1;
+            }
         }
         Ok(MiddlewareDecision::Continue)
     }

crates/zclaw-runtime/src/middleware/butler_router.rs

@@ -290,6 +290,8 @@ impl AgentMiddleware for ButlerRouterMiddleware {
         80
     }
 
+    fn parallel_safe(&self) -> bool { true }
+
     async fn before_completion(&self, ctx: &mut MiddlewareContext) -> Result<MiddlewareDecision> {
         // Only route on the first user message in a turn (not tool results)
         let user_input = &ctx.user_input;

crates/zclaw-runtime/src/middleware/evolution.rs

@@ -88,6 +88,8 @@ impl AgentMiddleware for EvolutionMiddleware {
         78 // 在 ButlerRouter(80) 之前
     }
 
+    fn parallel_safe(&self) -> bool { true }
+
     async fn before_completion(
         &self,
         ctx: &mut MiddlewareContext,

crates/zclaw-runtime/src/middleware/memory.rs

@@ -111,6 +111,7 @@ impl MemoryMiddleware {
 impl AgentMiddleware for MemoryMiddleware {
     fn name(&self) -> &str { "memory" }
     fn priority(&self) -> i32 { 150 }
+    fn parallel_safe(&self) -> bool { true }
 
     async fn before_completion(&self, ctx: &mut MiddlewareContext) -> Result<MiddlewareDecision> {
         tracing::debug!(

crates/zclaw-runtime/src/middleware/skill_index.rs

@@ -40,6 +40,7 @@ impl SkillIndexMiddleware {
 impl AgentMiddleware for SkillIndexMiddleware {
     fn name(&self) -> &str { "skill_index" }
     fn priority(&self) -> i32 { 200 }
+    fn parallel_safe(&self) -> bool { true }
 
     async fn before_completion(&self, ctx: &mut MiddlewareContext) -> Result<MiddlewareDecision> {
         if self.entries.is_empty() {

crates/zclaw-runtime/src/middleware/title.rs

@@ -41,6 +41,7 @@ impl Default for TitleMiddleware {
 impl AgentMiddleware for TitleMiddleware {
     fn name(&self) -> &str { "title" }
     fn priority(&self) -> i32 { 180 }
+    fn parallel_safe(&self) -> bool { true }
 
     // All hooks default to Continue — placeholder until LLM driver is wired in.
     async fn before_completion(&self, _ctx: &mut crate::middleware::MiddlewareContext) -> zclaw_types::Result<MiddlewareDecision> {