refactor(kernel): 移除 multi-agent feature gate — 33处 cfg 全部删除 (Phase 4A)

8 个文件移除 #[cfg(feature = "multi-agent")]，zclaw-kernel default features
新增 multi-agent。A2A 路由、agents、adapters 现在始终编译。

crates/zclaw-kernel/src/kernel/a2a.rs

@@ -1,16 +1,10 @@
 //! A2A (Agent-to-Agent) messaging
-//!
-//! All items in this module are gated by the `multi-agent` feature flag.
 
-#[cfg(feature = "multi-agent")]
 use zclaw_types::{AgentId, Capability, Event, Result};
-#[cfg(feature = "multi-agent")]
 use zclaw_protocols::{A2aAgentProfile, A2aCapability, A2aEnvelope, A2aMessageType, A2aRecipient};
 
-#[cfg(feature = "multi-agent")]
 use super::Kernel;
 
-#[cfg(feature = "multi-agent")]
 impl Kernel {
     // ============================================================
     // A2A (Agent-to-Agent) Messaging

crates/zclaw-kernel/src/kernel/adapters.rs

@@ -106,13 +106,11 @@ impl SkillExecutor for KernelSkillExecutor {
 
 /// Inbox wrapper for A2A message receivers that supports re-queuing
 /// non-matching messages instead of dropping them.
-#[cfg(feature = "multi-agent")]
 pub(crate) struct AgentInbox {
     pub(crate) rx: tokio::sync::mpsc::Receiver<zclaw_protocols::A2aEnvelope>,
     pub(crate) pending: std::collections::VecDeque<zclaw_protocols::A2aEnvelope>,
 }
 
-#[cfg(feature = "multi-agent")]
 impl AgentInbox {
     pub(crate) fn new(rx: tokio::sync::mpsc::Receiver<zclaw_protocols::A2aEnvelope>) -> Self {
         Self { rx, pending: std::collections::VecDeque::new() }

crates/zclaw-kernel/src/kernel/agents.rs

@@ -2,11 +2,8 @@
 
 use zclaw_types::{AgentConfig, AgentId, AgentInfo, Event, Result};
 
-#[cfg(feature = "multi-agent")]
 use std::sync::Arc;
-#[cfg(feature = "multi-agent")]
 use tokio::sync::Mutex;
-#[cfg(feature = "multi-agent")]
 use super::adapters::AgentInbox;
 
 use super::Kernel;
@@ -23,7 +20,6 @@ impl Kernel {
         self.memory.save_agent(&config).await?;
 
         // Register with A2A router for multi-agent messaging (before config is moved)
-        #[cfg(feature = "multi-agent")]
         {
             let profile = Self::agent_config_to_a2a_profile(&config);
             let rx = self.a2a_router.register_agent(profile).await;
@@ -52,7 +48,6 @@ impl Kernel {
         self.memory.delete_agent(id).await?;
 
         // Unregister from A2A router
-        #[cfg(feature = "multi-agent")]
         {
             self.a2a_router.unregister_agent(id).await;
             self.a2a_inboxes.remove(id);

crates/zclaw-kernel/src/kernel/mod.rs

@@ -8,16 +8,13 @@ mod hands;
 mod triggers;
 mod approvals;
 mod orchestration;
-#[cfg(feature = "multi-agent")]
 mod a2a;
 
 use std::sync::Arc;
 use tokio::sync::{broadcast, Mutex};
 use zclaw_types::{Event, Result, AgentState};
 
-#[cfg(feature = "multi-agent")]
 use zclaw_types::AgentId;
-#[cfg(feature = "multi-agent")]
 use zclaw_protocols::A2aRouter;
 
 use crate::registry::AgentRegistry;
@@ -56,11 +53,9 @@ pub struct Kernel {
     mcp_adapters: Arc<std::sync::RwLock<Vec<zclaw_protocols::McpToolAdapter>>>,
     /// Dynamic industry keyword configs — shared with Tauri frontend, loaded from SaaS
     industry_keywords: Arc<tokio::sync::RwLock<Vec<zclaw_runtime::IndustryKeywordConfig>>>,
-    /// A2A router for inter-agent messaging (gated by multi-agent feature)
-    #[cfg(feature = "multi-agent")]
+    /// A2A router for inter-agent messaging
     a2a_router: Arc<A2aRouter>,
     /// Per-agent A2A inbox receivers (supports re-queuing non-matching messages)
-    #[cfg(feature = "multi-agent")]
     a2a_inboxes: Arc<dashmap::DashMap<AgentId, Arc<Mutex<adapters::AgentInbox>>>>,
 }
 
@@ -135,7 +130,6 @@ impl Kernel {
         }
 
         // Initialize A2A router for multi-agent support
-        #[cfg(feature = "multi-agent")]
         let a2a_router = {
             let kernel_agent_id = AgentId::new();
             Arc::new(A2aRouter::new(kernel_agent_id))
@@ -159,9 +153,7 @@ impl Kernel {
             extraction_driver: None,
             mcp_adapters: Arc::new(std::sync::RwLock::new(Vec::new())),
             industry_keywords: Arc::new(tokio::sync::RwLock::new(Vec::new())),
-            #[cfg(feature = "multi-agent")]
             a2a_router,
-            #[cfg(feature = "multi-agent")]
             a2a_inboxes: Arc::new(dashmap::DashMap::new()),
         })
     }