Adv 2.0 D&D Phase 12 E2c: Siege Mode effects + threat-70 warning

§8.3 siege economics:
- applyDailyBurn now takes an explicit siege flag and enforces a 2× floor
  on supply burn even when HarshMod is below 2 (tier-1 zones still get
  starved out per spec).
- currentBurn mirrors the same precedence so status/briefing readouts
  stay consistent.
- Briefing rollover passes e.SiegeMode through, decoupling siege from
  the harsh-conditions composite.

§8.3 threat-70 warning: applyDailyThreatDrift emits a one-time
appendApproachingSiegeLog when the level crosses 70 (prevLevel<70 and
new level≥70). Pulls from a new flavor.ThreatClockApproachingSiege pool
seeded with the spec's verbatim warning beat plus two voice-matched
alternates.

Other siege effects (boss +20 HP / Legendary Resistance, cleared-room
respawn, no-short-rest enforcement) stay deferred to the combat-link
phase — ThreatBandInfo already exposes the flags that engine will read.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/plugin/dnd_expedition_cmd.go

@@ -257,8 +257,17 @@ func (p *AdventurePlugin) expeditionCmdStatus(ctx MessageContext) error {
 
 func currentBurn(exp *Expedition) float32 {
 	burn := exp.Supplies.DailyBurn
-	if exp.ThreatLevel > 60 || exp.SiegeMode {
-		// Harsh conditions: §4.1 / §8.3.
+	if exp.SiegeMode {
+		// §8.3: siege doubles supply burn outright, overriding HarshMod
+		// (which can be < 2 at low tiers).
+		mult := exp.Supplies.HarshMod
+		if mult < 2 {
+			mult = 2
+		}
+		return burn * mult
+	}
+	if exp.ThreatLevel > 60 {
+		// Harsh conditions: §4.1.
 		mult := exp.Supplies.HarshMod
 		if mult <= 0 {
 			mult = 1

internal/plugin/dnd_expedition_cycle.go

@@ -151,8 +151,8 @@ func scanExpeditionRows(rows *sql.Rows) ([]*Expedition, error) {
 // morning briefing DM, appends a log entry, and stamps last_briefing_at.
 func (p *AdventurePlugin) deliverBriefing(e *Expedition, now time.Time) error {
 	// Advance day + supply burn happen together at the morning rollover.
-	harsh := e.ThreatLevel > 60 || e.SiegeMode || e.TemporalStack > 0
-	newSupplies, burn := applyDailyBurn(e.Supplies, harsh)
+	harsh := e.ThreatLevel > 60 || e.TemporalStack > 0
+	newSupplies, burn := applyDailyBurn(e.Supplies, harsh, e.SiegeMode)
 	if err := updateSupplies(e.ID, newSupplies); err != nil {
 		return err
 	}

internal/plugin/dnd_expedition_supplies.go

@@ -158,13 +158,26 @@ func makeSupplies(tier ZoneTier, p SupplyPurchase) ExpeditionSupplies {
 
 // applyDailyBurn deducts one day's supplies from the snapshot (caller
 // persists). Returns the new snapshot and the SU consumed.
-func applyDailyBurn(s ExpeditionSupplies, harshActive bool) (ExpeditionSupplies, float32) {
+//
+// Multiplier precedence (§4.1, §8.3):
+//   - siege overrides everything with a hard 2× floor (even for tier 1
+//     where HarshMod is 1×) — the dungeon is actively starving you out.
+//   - otherwise, harshActive applies HarshMod (zone-tier scaled).
+func applyDailyBurn(s ExpeditionSupplies, harshActive, siege bool) (ExpeditionSupplies, float32) {
 	burn := s.DailyBurn
-	if harshActive {
-		burn *= s.HarshMod
-		if burn == s.DailyBurn { // HarshMod was 0 / unset
-			burn = s.DailyBurn
+	switch {
+	case siege:
+		mult := s.HarshMod
+		if mult < 2 {
+			mult = 2
 		}
+		burn *= mult
+	case harshActive:
+		mult := s.HarshMod
+		if mult <= 0 {
+			mult = 1
+		}
+		burn *= mult
 	}
 	s.Current -= burn
 	if s.Current < 0 {

internal/plugin/dnd_expedition_supplies_test.go

@@ -135,7 +135,7 @@ func TestMakeSupplies_FillsFromTier(t *testing.T) {
 
 func TestApplyDailyBurn_DrainsAndClamps(t *testing.T) {
 	s := ExpeditionSupplies{Current: 5, Max: 10, DailyBurn: 2, HarshMod: 1.5, ForagedToday: true}
-	s, burn := applyDailyBurn(s, false)
+	s, burn := applyDailyBurn(s, false, false)
 	if burn != 2 {
 		t.Errorf("burn = %v, want 2", burn)
 	}
@@ -146,13 +146,25 @@ func TestApplyDailyBurn_DrainsAndClamps(t *testing.T) {
 		t.Error("forage flag should reset on day rollover")
 	}
 	// Harsh active doubles via mult.
-	s, burn = applyDailyBurn(s, true)
+	s, burn = applyDailyBurn(s, true, false)
 	if burn != 3 { // 2 × 1.5
 		t.Errorf("harsh burn = %v, want 3", burn)
 	}
+	// Siege forces a 2× floor even when HarshMod is below 2 (tier 1).
+	t1 := ExpeditionSupplies{Current: 10, Max: 10, DailyBurn: 1, HarshMod: 1}
+	_, sb := applyDailyBurn(t1, false, true)
+	if sb != 2 {
+		t.Errorf("siege tier1 burn = %v, want 2 (forced floor)", sb)
+	}
+	// Siege at higher tier still uses HarshMod when it exceeds 2.
+	t5 := ExpeditionSupplies{Current: 10, Max: 10, DailyBurn: 1, HarshMod: 3}
+	_, sb5 := applyDailyBurn(t5, false, true)
+	if sb5 != 3 {
+		t.Errorf("siege tier5 burn = %v, want 3 (HarshMod)", sb5)
+	}
 	// Drain to floor.
 	for i := 0; i < 5; i++ {
-		s, _ = applyDailyBurn(s, false)
+		s, _ = applyDailyBurn(s, false, false)
 	}
 	if s.Current != 0 {
 		t.Errorf("expected current clamped to 0, got %v", s.Current)

internal/plugin/dnd_expedition_threat.go

@@ -113,6 +113,7 @@ func applyDailyThreatDrift(e *Expedition) (int, string, error) {
 	if delta == 0 {
 		return 0, reason, nil
 	}
+	prevLevel := e.ThreatLevel
 	prevBand := threatBandFor(e.ThreatLevel, e.SiegeMode)
 	if err := applyThreatDelta(e.ID, delta, reason); err != nil {
 		return 0, reason, err
@@ -132,9 +133,22 @@ func applyDailyThreatDrift(e *Expedition) (int, string, error) {
 	if newBand != prevBand && newBand > prevBand {
 		_ = appendThreatTransitionLog(e, newBand)
 	}
+	// E2c: §8.3 — one-time warning when crossing 70.
+	if prevLevel < 70 && e.ThreatLevel >= 70 {
+		_ = appendApproachingSiegeLog(e)
+	}
 	return delta, reason, nil
 }
 
+// appendApproachingSiegeLog records the §8.3 "begin warning at 70" beat
+// once per expedition. Caller is responsible for only firing it on the
+// crossing edge (see applyDailyThreatDrift).
+func appendApproachingSiegeLog(e *Expedition) error {
+	line := flavor.Pick(flavor.ThreatClockApproachingSiege)
+	return appendExpeditionLog(e.ID, e.CurrentDay, "threat",
+		"threat clock past 70 — siege approaches", line)
+}
+
 // appendThreatTransitionLog records a band-crossing in the expedition log
 // with the prewritten TwinBee narration for that band.
 func appendThreatTransitionLog(e *Expedition, band ThreatBand) error {

internal/plugin/dnd_expedition_threat_test.go

@@ -155,6 +155,52 @@ func TestDeliverBriefing_AppliesThreatDrift(t *testing.T) {
 	}
 }
 
+func TestApplyDailyThreatDrift_LogsApproachingSiegeOnceAt70(t *testing.T) {
+	setupZoneRunTestDB(t)
+	uid := id.UserID("@exp-threat-70warn:example")
+	defer cleanupExpeditions(uid)
+
+	exp, err := startExpedition(uid, ZoneGoblinWarrens, "",
+		ExpeditionSupplies{Current: 10, Max: 10, DailyBurn: 1, HarshMod: 1})
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Seed to 68 — a +3 drift crosses 70.
+	if err := applyThreatDelta(exp.ID, 68, "seed"); err != nil {
+		t.Fatal(err)
+	}
+	exp, _ = getExpedition(exp.ID)
+	if _, _, err := applyDailyThreatDrift(exp); err != nil {
+		t.Fatal(err)
+	}
+	entries, _ := recentExpeditionLog(exp.ID, 20)
+	count := 0
+	for _, e := range entries {
+		if e.Type == "threat" && strings.Contains(e.Summary, "past 70") {
+			count++
+		}
+	}
+	if count != 1 {
+		t.Errorf("expected exactly one approaching-siege log, got %d", count)
+	}
+
+	// A subsequent drift past 70 should not re-emit the warning.
+	exp, _ = getExpedition(exp.ID)
+	if _, _, err := applyDailyThreatDrift(exp); err != nil {
+		t.Fatal(err)
+	}
+	entries, _ = recentExpeditionLog(exp.ID, 20)
+	count = 0
+	for _, e := range entries {
+		if e.Type == "threat" && strings.Contains(e.Summary, "past 70") {
+			count++
+		}
+	}
+	if count != 1 {
+		t.Errorf("expected approaching-siege log still 1 after second drift, got %d", count)
+	}
+}
+
 func TestApplyBossDefeatThreat_DropsLevel(t *testing.T) {
 	setupZoneRunTestDB(t)
 	uid := id.UserID("@exp-boss-threat:example")