fix(host): preserve subagent continuation ownership

packages/host/apiproxy/src/api/commands.ts

@@ -1,8 +1,8 @@
 /**
  * commands domain contract: the web catalog/dispatch face of the host command
- * registry (`ctx.commands`). Both methods address one session's agent via
- * `sessionId` — every served session has an Agent (Session+Agent are born
- * together), so there is no agent-less surface on this wire.
+ * registry (`ctx.commands`). Both methods address an ordinary session's Agent
+ * via `sessionId`, resuming it when cold. Session-backed subagents reject with
+ * `agent-busy` and retain their dedicated continuation owner.
  */
 
 import type { CommandId } from '@deepseek-ai/dsh-commands/brand'
@@ -27,7 +27,8 @@ export interface CommandDescriptor {
 export interface CommandsApi {
   /**
    * Lists the addressed agent's effective command catalog (name-sorted,
-   * globals plus its scoped shadows).
+   * globals plus its scoped shadows). Session-backed subagents reject with
+   * `agent-busy`.
    */
   list(request: RpcRequest<{ sessionId: SessionId }>): Promise<RpcResponse<{ commands: readonly CommandDescriptor[] }>>
 
@@ -42,6 +43,7 @@ export interface CommandsApi {
    * pairing id, letting the issuing client correlate this acknowledgment
    * with that flow node. The signal rides beside the request, never on the
    * wire: the fetch carrier's request signal cancels the running handler.
+   * Session-backed subagents reject with `agent-busy` before dispatch.
    */
   execute(request: RpcRequest<{ sessionId: SessionId; line: string }>, signal: AbortSignal):
   Promise<RpcResponse<{ matched: boolean; commandId?: CommandId }>>

packages/host/apiproxy/src/api/goals.ts

@@ -22,7 +22,11 @@ export interface GoalRef {
   readonly revision: number
 }
 
-/** Goal-domain unary methods (every mutation resolves the session's agent and applies one CAS-guarded verb). */
+/**
+ * Goal-domain unary methods. Every mutation resolves an ordinary session's
+ * Agent and applies one CAS-guarded verb; session-backed subagents reject with
+ * `agent-busy`.
+ */
 export interface GoalsApi {
   /** Create and arm a goal. */
   create(request: RpcRequest<{ sessionId: SessionId; objective: string; maxGoalRounds?: number }>):

packages/host/apiproxy/src/api/sessions.ts

@@ -219,17 +219,22 @@ export interface SessionsApi {
    * the client needs a fresh baseline already pulls the tail page, and
    * loadOlder (the only beforeSeq path) is the only path that never needs one.
    * A deployment without the registry serves histories without the block.
+   * Reading history uses an attached Session or persistence inspection and
+   * never resumes or publishes an Agent.
    */
   history(request: RpcRequest<{ sessionId: SessionId; beforeSeq?: number; maxMessages?: number }>):
   Promise<RpcResponse<{ events: HistoryEntry[]; hasMore: boolean; projections?: SessionProjectionsBlock }>>
 
-  /** Reads a fresh advisory model directory for this session. Provider lookups run independently. */
+  /**
+   * Reads a fresh advisory model directory for an ordinary session. Provider
+   * lookups run independently; subagents reject with `agent-busy`.
+   */
   models(request: RpcRequest<{ sessionId: SessionId }>): Promise<RpcResponse<SessionModels>>
 
   /**
    * Selects the complete target for this session. Exact model metadata
    * validates an optional reasoning effort, while catalog membership remains
-   * advisory.
+   * advisory. Session-backed subagents reject with `agent-busy`.
    */
   selectModel(request: RpcRequest<{
     sessionId: SessionId
@@ -245,6 +250,7 @@ export interface SessionsApi {
    * normalized accepted title and the title event's seq return so the caller
    * can settle its projection cell without waiting for the push frame. A
    * title that normalizes to empty fails with `title-invalid`.
+   * Session-backed subagents reject with `agent-busy`.
    */
   rename(request: RpcRequest<{ sessionId: SessionId; title: string }>):
   Promise<RpcResponse<{ title: string; seq: number }>>
@@ -265,23 +271,30 @@ export interface SessionsApi {
    * falls back to the source's last completed turn. An in-log anchor whose
    * turn is still open fails with `fork-unavailable` instead of clipping to
    * an earlier turn. The child inherits the source cwd, latest logged model
-   * target, workspace attachment, and `parentSessionId` lineage; the seed
-   * prefix carries the source title.
+   * target and `parentSessionId` lineage; the seed prefix carries the source
+   * title. Reading the source uses attached state or persistence inspection
+   * without acquiring an Agent. Workspace attachment follows the source
+   * directly when it belongs to one.
    */
   fork(request: RpcRequest<{ sessionId: SessionId; atSeq?: number }>):
   Promise<RpcResponse<{ sessionId: SessionId }>>
 
-  /** Sends a message. content is core's ContentBlock[] verbatim; mode maps 1:1 — queue→send, steer→steer. */
+  /** Sends a message to an ordinary session Agent. Session-backed subagents reject with `agent-busy` and use `subagent.prompt`. */
   prompt(request: RpcRequest<{ sessionId: SessionId; mode: 'queue' | 'steer'; content: ContentBlock[] }>):
   Promise<RpcResponse<{ accepted: true; command?: { kind: 'success'; text?: string } }>>
 
   /**
-   * Edits or removes one pending queued occurrence.
+   * Edits or removes one pending queued occurrence on an ordinary session.
+   * Session-backed subagents reject with `agent-busy`.
    */
   updateQueue(request: RpcRequest<{ sessionId: SessionId; itemId: InboxItemId; action: QueueAction }>):
   Promise<RpcResponse<{ accepted: true }>>
 
-  /** Stops the active turn, preserving pending inbox work that resumes in FIFO order after cancellation settles. */
+  /**
+   * Stops an ordinary session's active turn, preserving pending inbox work
+   * that resumes in FIFO order after cancellation settles. Session-backed
+   * subagents reject with `agent-busy`.
+   */
   cancel(request: RpcRequest<{ sessionId: SessionId }>): Promise<RpcResponse<{ accepted: true }>>
 
 }