fix: address PR #1802 review round

- listChildren reads the session store via strict ctx.get (property proxy
  is caller-scoped), orders candidates branchlessly, narrows the cold-read
  return type, and pins the cost model and store/registry composition gaps
  with tests; per-file coverage restored
- acp-agent and headless-agent compositions mount session-projection; a
  keyless snapshot pins the descriptor-less diagnostic row
- api-proxy cold spec pins header-origin ownership and the legacy
  descriptor-only opt-out
- design note ships as implemented with its English pairing; companion
  notes and core-data-structures pages synced

.agents/notes/implemented/feature/2026-07-22-durable-subagent-catalog-and-list-agents.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/feature/2026-07-22-durable-subagent-catalog-and-list-agents.md
-2026-07-22-durable-subagent-catalog-and-list-agents.md: 0dd7eebac74689004014248c7178dba540ef4662
-2026-07-22-durable-subagent-catalog-and-list-agents.zh.md: 33b0296cf9914d1975fb1dc84564b498a09bd511
+2026-07-22-durable-subagent-catalog-and-list-agents.md: 1de93cc1374e8e86bace6af94b51efe94b38f89a
+2026-07-22-durable-subagent-catalog-and-list-agents.zh.md: fe5422c497b87bb39d43ac97cb5d1a9bed9fcbfb

.agents/notes/implemented/feature/2026-07-22-durable-subagent-catalog-and-list-agents.md

@@ -12,6 +12,8 @@ Enumeration must cross-check immutable session lineage, descriptor validity, and
 
 ## Decision
 
+**Superseded read path.** [Subagent list identity via the projection unit](../architecture/2026-08-06-subagent-list-identity-projection.md) replaces this note's enumeration and per-child read design: `listChildren` now merges the live session store with optional session persistence directly and serves each child's mode/label from the registered `subagent` projection unit — no session-query dependency, no list-time descriptor scan — and that note owns the current listing semantics, including the diagnostic mapping. This note remains the authority for descriptor persistence, the mode-discriminated descriptor as durable identity, direct-parent authorization, and the model-facing `list_agents` projection; the trace-based read mechanics below are decision context, not current behavior.
+
 Parent-to-child enumeration is a service capability with consumer-specific projections. `SubagentService.listChildren(parentSessionId: SessionId)` ([subagent/src/index.ts](../../../../packages/subagent/subagent/src/index.ts)) does the following:
 
 - use `ctx.sessionQuery.traceSession(parentSessionId)` to obtain the parent's direct live-preferred child sessions;

.agents/notes/implemented/feature/2026-07-22-durable-subagent-catalog-and-list-agents.zh.md

@@ -12,6 +12,8 @@ Status: implemented
 
 ## 决策
 
+**列表读路径已被取代。**[subagent 列表经投影单元读取身份](../architecture/2026-08-06-subagent-list-identity-projection.md)取代了本记录的枚举与逐 child 读取设计:`listChildren` 现在直接合并存活会话存储与可选的会话持久化,并从注册的 `subagent` projection unit 读取每个 child 的 mode/label——不依赖会话查询,也不在列表时扫描描述符;当前的列表语义(含 diagnostic 映射)以该记录为准。本记录仍是描述符持久化、以 mode 判别的描述符作为持久身份、直接 parent 鉴权与面向模型的 `list_agents` 投影的权威;下文基于追踪的读取机制是决策背景,不再是当前行为。
+
 parent 到 child 的枚举是一项带消费方专用投影的服务功能。`SubagentService.listChildren(parentSessionId: SessionId)`（[subagent/src/index.ts](../../../../packages/subagent/subagent/src/index.ts)）执行以下操作：
 
 - 使用 `ctx.sessionQuery.traceSession(parentSessionId)` 获取 parent 的直接且实时优先的 child 会话；