docs: audit package limitations on current stack

packages/ui/user-approval/README.md

@@ -11,3 +11,10 @@ The seam also owns the per-session POLICY tier ([the sandbox RFC § Per-session
 One seam serves both ask paths of [the sandbox RFC](../../../docs/rfc/implemented/feature/2026-07-06-sandbox.md): the `tools/pre-execute` `ask` decision (routed by [`@deepseek-ai/dsh-tools`](../../core/tools/) when this service is mounted; degrading to deny when it is not), and the sandbox post-denial escalated retry (the bash tool's `sandbox_permissions` gate in [`@deepseek-ai/dsh-tool-bash`](../../bash/tool-bash/) — [the sandbox RFC § Escalation](../../../docs/rfc/implemented/feature/2026-07-06-sandbox.md)). The full design: [the approval-seam RFC](../../../docs/rfc/implemented/feature/2026-07-06-approval-seam.md).
 
 Answerers today: the ACP bridge ([`@deepseek-ai/dsh-acp`](../../ui/acp/)) forwards to the editor's `session/request_permission` prompt for agents it owns. The audit events are log-only session records — the model only ever sees the tool result the asker derives from the outcome.
+
+## Known Limitations and Deferred Work
+
+- **Requests are valid only inside an open turn** — an idle or between-turn caller throws before auditing; a durable out-of-turn approval workflow is deferred.
+- **Only one-shot grants exist** — the outcome vocabulary has `allowed-once` but no `allow-always`, remembered rule, revocation, or grant store; session policy is only `ask` / `never`.
+- **The request carries no tool arguments** — a UI must correlate `callId` with an already rendered tool call, and a call-less request cannot be presented by the shipped ACP answerer.
+- **No built-in answerer** — headless or incompletely composed deployments resolve `unavailable` and fail closed; the service itself never prompts a human.