feat(dx): scopeHost, agent-aware ACP presentation, and the scoped-dispatch drift gate

scopeHost(ctx, services) is the sanctioned way to mint scopes in tests: it
names absent services loudly instead of the cryptic cordis without-inject
dead end, and catches the silent-no-op host (cordis resolves a
dependency-pending fiber's await without running the inject callback).

The ACP ToolPresenter resolves presentations through the session agent's
view (tools.get(name, agent)) so a scoped/shadowed tool renders with the
same definition that executed.

verify-scoped-dispatch (doc-sync + pre-push) pins the dev-invariants
carrier table against the declaration JSDoc set: an event enforced but
undocumented, documented but unenforced, or a registry-subject notification
leaking into the table fails the build. subagent/start|end docs gain their
scoped-dispatch sentence (a real gap the gate caught on first run).

packages/subagent/subagent/src/index.ts

@@ -86,6 +86,10 @@ declare module 'cordis' {
      * A subagent run started — emitted after the provider is resolved and its
      * capabilities validated, as the child run begins. Paired with
      * {@link Events['subagent/end']}.
+     * Scope-filtered dispatch (`@deepseek-ai/dsh-scope`): the carrier is keyed
+     * by the DELEGATING PARENT — a listener registered through the parent's
+     * `agent.ctx` observes only its own delegations; a plain plugin listener
+     * observes every run.
      * @param info - which provider started which child agent.
      * @mode emit
      */
@@ -93,6 +97,10 @@ declare module 'cordis' {
     /**
      * A subagent run settled — emitted when {@link SubagentRun.result}
      * resolves (any stop reason). Paired with {@link Events['subagent/start']}.
+     * Scope-filtered dispatch (`@deepseek-ai/dsh-scope`): the carrier is keyed
+     * by the DELEGATING PARENT — a listener registered through the parent's
+     * `agent.ctx` observes only its own delegations; a plain plugin listener
+     * observes every run.
      * @param info - the run identity plus stop reason and final output.
      * @mode emit
      */