agent-pre-step 2

Inbox input guard for dsh: a claimed inbox entry that is not a UserMessage crashes the turn inside whichever module reads it first, and the report names that reader - discussion #7363 ends ~1ms after turn/start, before any step/start, with "Cannot read pr

Balance guard for dsh: reads GET /user/balance on the agent/pre-step waterfall and refuses the step when the provider says the account cannot pay for it (is_available=false, or the balance is at/below a configured floor). The refusal dispatches no model r