docs(runtime): internal/runtime/loop 44 个文件注释改中文（逐行 1:1，代码零字节改动）

主人 2026-10-03 拍板「注释一律中文」；本模块按长期分批协议（一个模块一次派工）执行。
注释行数 1329 → 1329 逐行 1:1（含中文 33 → 1304）；行尾注释 5 条一并译。
校验：机械校验（非注释改动行）= 空；独立 Go AST 程序（剥注释复渲）证明 44/44 文件代码全等；
全树 go test ./... 58 包 ok / 0 FAIL；交叉编译绿。
gofmt：capacity_loop_test.go / flow.go 改动前即未格式化，按铁律保留原样未动。

internal/runtime/loop/flow_branch.go

@@ -2,22 +2,22 @@ package loop
 
 import "context"
 
-// flowBranchKey is the context key marking a Run as a branch of another
-// session's flow graph. It is set by the orchestration layer (through
-// WithFlowBranch) before it drives a sub-agent's Run.
+// flowBranchKey 是标记某个 Run 为另一会话 flow 图分支的 context key。
+// 它由 orchestration 层（经 WithFlowBranch）在驱动
+// 子代理 Run 之前设置。
 type flowBranchKey struct{}
 
-// WithFlowBranch returns ctx marking the current Run as a branch: its spans fold
-// into parentSession's live flow graph and the Run neither starts nor ends a
-// round of its own — the owning session's round does. It is how the orchestration
-// layer attributes a sub-agent's work to the session that spawned it, so parallel
-// sub-agents render as swimlanes of one graph instead of replacing the frontend's
-// single flowGraph with a graph of their own (design/19 §2).
+// WithFlowBranch 返回 ctx，把当前 Run 标记为分支：它的 span 并入
+// parentSession 的实时 flow 图，且该 Run 自身既不开始也不结束
+// 轮次 —— 由所属会话的轮次负责。orchestration 层正是靠它把
+// 子代理的工作归属到派生它的会话，使并行的
+// 子代理渲染为同一张图的泳道，而不是用各自的图
+// 替换前端唯一的 flowGraph（design/19 §2）。
 //
-// An empty parentSession still marks the Run as a branch: it owns no round and
-// publishes nothing. That is the state of a background sub-agent nobody attributed
-// to a session, and it must not silently become a graph of its own. A nil ctx is
-// returned unchanged.
+// 空的 parentSession 仍把该 Run 标记为分支：它不拥有轮次、
+// 不发布任何东西。这正是无人归属到会话的后台子代理的
+// 状态，它不得悄悄变成属于自己的一张图。nil ctx
+// 原样返回。
 func WithFlowBranch(ctx context.Context, parentSession string) context.Context {
 	if ctx == nil {
 		return ctx
@@ -25,9 +25,9 @@ func WithFlowBranch(ctx context.Context, parentSession string) context.Context {
 	return context.WithValue(ctx, flowBranchKey{}, parentSession)
 }
 
-// flowBranch reports the parent session recorded by WithFlowBranch and whether the
-// Run is a branch at all. A non-branch Run owns its own round and publishes under
-// its own session id.
+// flowBranch 报告 WithFlowBranch 记录的父会话以及
+// 该 Run 是否本就是分支。非分支的 Run 拥有自己的轮次并在
+// 自己的 session id 下发布。
 func flowBranch(ctx context.Context) (string, bool) {
 	if ctx == nil {
 		return "", false
@@ -40,9 +40,9 @@ func flowBranch(ctx context.Context) (string, bool) {
 	return s, true
 }
 
-// flowOwner returns the session whose flow graph should receive this Run's spans:
-// the branch parent when the Run is a sub-agent branch (empty when the branch is
-// unattributed, which suppresses publication), otherwise the Run's own sessionID.
+// flowOwner 返回应当接收该 Run span 的 flow 图所属会话：
+// 当该 Run 是子代理分支时取分支父级（分支未归属时为空，
+// 此时抑制发布），否则取该 Run 自身的 sessionID。
 func flowOwner(ctx context.Context, sessionID string) string {
 	if parent, isBranch := flowBranch(ctx); isBranch {
 		return parent
@@ -50,14 +50,14 @@ func flowOwner(ctx context.Context, sessionID string) string {
 	return sessionID
 }
 
-// FlowOwnerFromContext returns the session whose flow graph owns work started
-// from ctx: the branch parent when ctx runs inside a sub-agent branch, otherwise
-// the session id the enclosing Run was driven with (empty when neither is set).
+// FlowOwnerFromContext 返回拥有从 ctx 启动的工作的 flow 图所属会话：
+// 当 ctx 运行于子代理分支内时取分支父级，否则
+// 取外层 Run 被驱动的 session id（两者都未设置时为空）。
 //
-// A tool that dispatches background work — the sub-agent spawn tool — passes this
-// as the parent session, so a sub-agent spawned from inside another sub-agent
-// stays attributed to the same top-level graph instead of to an id that owns no
-// graph.
+// 派发后台工作的工具 —— 子代理派生工具 —— 把它
+// 作为父会话传入，使在另一个子代理内部派生的子代理
+// 保持在同一个顶层图的归属之下，而不是归属到一个不拥有
+// 任何图的 id。
 func FlowOwnerFromContext(ctx context.Context) string {
 	if parent, isBranch := flowBranch(ctx); isBranch {
 		return parent