feat(session,runtime): 多角色并存—按会话选角（迁移0011 + 按回合解析 + agent池 + 提取器修正）

按 DevDocs/design/22 批次 1 后端（§2/§3/§4.1-4.5/§4.7/§5 验收 1-6）。
- 迁移 0011：chat_sessions.persona_id + chat_messages.persona_id（均 DEFAULT ''，无回填 → 升级零风险）；同步包内幂等 DDL；**真实库升级验证**（拷贝 data/cyrene.db 到临时目录跑 MigrateUp：既有 1 会话/109 消息 persona 仍为 ''，原库未被触碰）
- history：SessionMeta/Message 加 PersonaID + SetSessionPersona；ListSessions/List/scan/Append 带上
- runtime：SessionEnv.PersonaID + loop.personaFor(ctx) 替换固定 l.personaID（memory/request/turn）+ **agent 池**（Options.Agents，按角色取 instructions，未命中回落）+ **提取器不再把 persona 烤死在构造期**（多角色下记忆不再永远记在 cyrene 名下）+ **thinking 旋钮改为按会话角色解析**（否则角色 Y 会用角色 X 的预算/展示）
- gateway：会话 DTO/POST/PATCH 支持 personaId；ws/rest/voice 的 OwnerEnv 硬编改为**按会话解析角色**（actor 元数据语义不变）；admin memories 搜索去掉硬编 cyrene
- Docs/api-client v0.42；**两处有意的行为收紧**已写明：POST /sessions body 非法 JSON → 400（原先完全忽略 body；空/null/{} 仍 201）；POST /admin/memories/search 省略 personaId 且无默认角色 → 400（原先默认查 cyrene）
- 测试：design/22 §5 验收 1-6（记忆隔离/提示词首条 system/情绪按角色/提取 persona 归属/迁移兼容）+ 进程内 e2e（断言 adapter 收到的 model.Request.Messages[0] 即该角色的 systemPrompt）
- **已知未做（留批次 2 / 待确认）**：① IM 与渠道级未做 → **§7-3「owner 私聊镜像随主会话角色」尚未生效**；② 请求级覆盖未实现（本批只做会话级）；③ **§7-5 的「上下文发送角色标记」只完成存储+DTO 半边**——消息 persona 已落库且 DTO 已带，但模型上下文不从 chat_messages 重建，「第 N 条是谁说的」尚未进上下文（需确认是否属批次 2）；④「切角色重建摘要」当前是空操作（压缩未接线）；⑤ thinking 旋钮仅在流式路径生效（非流式 agent.RunStep 不带，A 批次既有性质）
- 验收：go build/vet/test 全绿 + linux/amd64 与 darwin/arm64 交叉编译（既有 flake 本轮未触发；同批 session_orchestrator.go 一度 501 行 → 抽出 session_tail.go）

internal/runtime/memory/extract.go

@@ -38,8 +38,11 @@ type ManualExtractor struct {
 	roleID    string
 }
 
-// NewManualExtractor builds a ManualExtractor whose extracted items are scoped
-// to personaID and roleID, isolated from other personas (design §4).
+// NewManualExtractor builds a ManualExtractor whose extracted items carry
+// personaID/roleID as their author. Like the LLM extractor, the persona is a
+// default rather than the authority: a multi-role caller builds it with a blank
+// persona and stamps each item with the turn's role when persisting it
+// (design/22 §4.2), so pass "" for a role-agnostic extractor.
 func NewManualExtractor(personaID, roleID string) *ManualExtractor {
 	return &ManualExtractor{personaID: personaID, roleID: roleID}
 }

internal/runtime/memory/llmextractor.go

@@ -50,11 +50,15 @@ type LLMExtractor struct {
 	seen map[string]struct{}
 }
 
-// NewLLMExtractor builds an LLMExtractor whose extracted items are authored by
-// personaID/roleID and default to ScopePersona + KindRelationship when the model
-// does not specify otherwise. A nil adapter is rejected at use time via
-// ErrNilAdapter, matching the lazy construction pattern of the rest of the
-// runtime; callers may pass nil to build the struct and wire the adapter later.
+// NewLLMExtractor builds an LLMExtractor whose extracted items default to
+// ScopePersona + KindRelationship when the model does not specify otherwise, and
+// carry personaID/roleID as their author. The persona is a *default*, not the
+// authority: a multi-role caller (the runtime loop, design/22 §4.2) builds the
+// extractor with a blank persona and stamps each item with the role that produced
+// the turn, so pass "" for a role-agnostic extractor. A nil adapter is rejected at
+// use time via ErrNilAdapter, matching the lazy construction pattern of the rest
+// of the runtime; callers may pass nil to build the struct and wire the adapter
+// later.
 func NewLLMExtractor(adapter model.Adapter, personaID, roleID string) *LLMExtractor {
 	return &LLMExtractor{
 		adapter:   adapter,
@@ -170,6 +174,13 @@ func parseCandidates(s string) ([]llmCandidate, error) {
 // and any content already emitted by this extractor (idempotent dedup). It
 // requires e.mu; only valid items mark their dedup key so a malformed candidate
 // does not suppress a later valid one with the same text.
+//
+// The persona is NOT required here even though MemoryItem.validate demands one: a
+// role-agnostic extractor (personaID == "") is legitimate — the caller that knows
+// the turn's role (the loop) stamps the persona when it persists the item — and
+// rejecting the item here would silently drop every memory of a multi-role
+// process. Content/scope/kind, which only this package can judge, are still
+// enforced.
 func (e *LLMExtractor) dedupeAndBuild(cands []llmCandidate) []MemoryItem {
 	e.mu.Lock()
 	defer e.mu.Unlock()
@@ -195,7 +206,7 @@ func (e *LLMExtractor) dedupeAndBuild(cands []llmCandidate) []MemoryItem {
 			Confidence:         c.Confidence,
 			SourceConversation: strings.TrimSpace(c.Source),
 		}
-		if err := it.validate(); err != nil {
+		if !it.Scope.valid() || !it.Kind.valid() {
 			continue
 		}
 		e.seen[key] = struct{}{}