feat(backthink): 自主思考强化 P1——主会话上下文+owner env+去压制(design/20)

backthink 从"心跳空转(独立sess-backthink+写死nothing to report宏)"改成"看得见主人、
能读写记忆、能调工具"：think 读主会话最近20条(history.Recent,倒序映射)作为上下文 +
 重写引导prompt(温暖/有针对性/主动表达,删掉 Do not produce chat-style message) + 注入
 loop.OwnerEnv(MemWritable=true/ActorOwner/全工具)。
- context.go: mainContext/recentProvider/thinkInput/guidancePrompt
- thinker.go: LoopThinker 加 recent;Think 读主会话上下文+OwnerEnv+MutedBroadcast
- wire.go: NewLoopThinker(a.loop, a.history)
- 刻意偏离(安全): loop.Run session id 仍用 sess-backthink(不写"web"),避免与用户实时回合
  checkpoint/中断窗口复用污染;上下文来源+运行环境=主会话/owner env,目标达成。红线靠actor元数据。
- 测试: prompt无压制/有鼓励;主会话消息映射;nil退化;端到端Think(owner env 生效)
验收: build/vet/test 全绿+windows/darwin交叉编译绿. P2(主动推送+渠道选择)后置.

internal/services/backthink/thinker.go

@@ -5,43 +5,43 @@ import (
 	"fmt"
 
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/loop"
-	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
 )
 
 // LoopThinker adapts a *loop.Loop into a Thinker. It is the production wiring
-// that lets a background pass drive the full tool loop (memory injection, model
-// steps, tool calls such as IoT/calendar/reminders) without the service knowing
-// the loop's concrete shape.
+// that lets an autonomous background pass drive the full tool loop (memory
+// injection, model steps, tool calls such as IoT/calendar/reminders) while seeing
+// the main session's recent conversation and running under the owner environment.
 type LoopThinker struct {
-	loop *loop.Loop
+	loop   *loop.Loop
+	recent recentProvider
 }
 
-// NewLoopThinker wraps l as a Thinker.
-func NewLoopThinker(l *loop.Loop) *LoopThinker { return &LoopThinker{loop: l} }
+// NewLoopThinker wraps l as a Thinker over the given recent-messages provider
+// (*history.Store in production; nil degrades the think to the guidance prompt
+// alone, see mainContext).
+func NewLoopThinker(l *loop.Loop, recent recentProvider) *LoopThinker {
+	return &LoopThinker{loop: l, recent: recent}
+}
 
 // Think runs one unattended think through the wrapped loop and returns the
-// conclusion text. It returns ErrNoLoop when no loop was injected.
+// conclusion text. It inherits the main session's recent conversation as input
+// context and injects the owner session environment (MemWritable=true, ActorOwner,
+// full tool set) so the think can read/write memory and call tools. The loop's
+// Run session id is the service's own (not the main session id) so the think never
+// collides with the live main session's durable checkpoint store (design/20).
+// It returns ErrNoLoop when no loop was injected.
 func (t *LoopThinker) Think(ctx context.Context, sessionID, trigger string) (string, error) {
 	if t.loop == nil {
 		return "", ErrNoLoop
 	}
-	messages := []model.Message{model.TextMessage(model.RoleUser, backgroundPrompt(trigger))}
+	recent := mainContext(ctx, t.recent)
+	messages := thinkInput(recent, trigger)
+	envCtx := loop.WithSessionEnv(ctx, loop.OwnerEnv())
 	// Mute UI broadcast: background reflection must not leak its intermediate
 	// reasoning into the user-facing chat stream (it only needs the conclusion).
-	res, err := t.loop.Run(loop.WithMutedBroadcast(ctx), sessionID, messages)
+	res, err := t.loop.Run(loop.WithMutedBroadcast(envCtx), sessionID, messages)
 	if err != nil {
 		return "", fmt.Errorf("backthink: think: %w", err)
 	}
 	return res.Text, nil
 }
-
-// backgroundPrompt is the instruction handed to the runtime for one unattended
-// thought. It explicitly avoids asking for a chat-style message to the user.
-func backgroundPrompt(trigger string) string {
-	return "[background autonomous reflection]\n" +
-		"Trigger: " + trigger + "\n" +
-		"Review recent context, device states, calendar and reminders. Decide " +
-		"whether anything is worth proactively telling the owner. If nothing " +
-		"matters, conclude \"nothing to report\". Keep the conclusion to one or " +
-		"two sentences. Do not produce a chat-style message to the user."
-}