A fourth formal round of Iran-US nuclear negotiations will NOT be publicly announced or formally scheduled by 2026-05-17, despite the US having formally responded to Iran's latest peace proposal.

Begin from a base rate of approximately 35% for a formal next-round scheduling within 14 days given active-but-stalled negotiations with an open back-channel. Three sequential adjustments apply. Upward: the Austrian price-discovery framework identifies robust bilateral costly-signaling — Iran’s Day 66 Hormuz closure maintained while still engaging, and the US formal reply rather than dismissal, both indicate active convergence below walk-away prices. The Oman channel being already activated reduces transaction costs to near-minimum for this cycle. This pushes probability to approximately 43%. Downward: the Marxist arms-sales lock-in is the most concrete short-term structural constraint identified across all four frameworks — $8.6bn in regional commitments that depreciate on visible diplomatic progress operates as an embedded material interest independent of ideology, giving the arms-and-containment fraction of US capital a dominant-strategy incentive against announcement. Combined with the Keynesian diplomatic liquidity trap (both parties rationally prefer uncommitted positions under irreducible uncertainty), this returns probability to approximately 42%. Neutral-to-downward: the Institutionalist sequencing dispute (who bears de-escalation switching cost) and the Trump-Xi frame shift (absorbing Hormuz urgency) neither conclusively block nor enable scheduling but raise fragility — even if scheduling occurs, it may be announced and retracted. The great-power absorption effect is particularly significant: if Hormuz is now on the Trump-Xi agenda, the bilateral urgency that would otherwise force US-Iran scheduling is partly displaced. Net synthesis: the mechanisms favoring ‘no’ are more observable and concrete in the 14-day window (arms-sales commitments, visible veto players, unresolved sequencing dispute, great-power absorption) than the mechanisms favoring ‘yes’ (price-discovery signals, institutional pathway, historical JPOA precedent). Final probability: approximately 45% for announcement, 55% against. Low confidence-in-confidence reflects genuine model uncertainty — back-channel resolution can emerge suddenly and outside public view, and the Austrian and Institutionalist ‘yes’ cases are substantive, not dismissible.