Adv 2.0 D&D Phase 12 E3d: Feywild Crossing time distortion

§7.4 daily 1d6 distortion roll fires at briefing time:
  • 1–2 normal day (no override)
  • 3–4 half-day → 0.5× burn multiplier override
  • 5    double-day → 2.0× burn + extra wandering check at recap
  • 6    time loop → narration only; combat-link reads on next room

Refactors applyZoneTemporalPreBurn to return TemporalBurnOverride
(Multiplier-based) instead of a force-double bool. Sunken Temple's
Day-6 tidal piggybacks on the same override pipeline (2.0×) instead
of the siege-flag hack.

Persists the day's distortion bucket to RegionState["feywild_today"]
so the recap path can fire the §7.4 extra wandering check on
double-day.

Reuses flavor.FeywildTimeDistortionHalf / Double / Loop per
feedback_reuse_existing_flavor.

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

internal/plugin/dnd_expedition_temporal.go

@@ -1,12 +1,33 @@
 package plugin
 
 import (
+	"encoding/json"
 	"fmt"
+	"math/rand/v2"
 	"strings"
 
+	"gogobee/internal/db"
 	"gogobee/internal/flavor"
 )
 
+// randIntN wraps math/rand/v2 IntN so feywildRollFn's seam stays
+// dependency-free for tests.
+func randIntN(n int) int { return rand.IntN(n) }
+
+// persistRegionState writes the in-memory RegionState back to the DB.
+func persistRegionState(e *Expedition) error {
+	b, err := json.Marshal(e.RegionState)
+	if err != nil {
+		return err
+	}
+	_, err = db.Get().Exec(`
+		UPDATE dnd_expedition
+		   SET region_state = ?,
+		       last_activity = CURRENT_TIMESTAMP
+		 WHERE expedition_id = ?`, string(b), e.ID)
+	return err
+}
+
 // Phase 12 E3 — Zone-specific Temporal Events.
 // Spec: gogobee_expedition_system.md §7.
 //
@@ -72,19 +93,32 @@ func zoneTemporalHarsh(e *Expedition) bool {
 	return false
 }
 
+// TemporalBurnOverride lets a zone-temporal event short-circuit the
+// default §4.1 burn pipeline with a fixed multiplier on DailyBurn.
+// When Multiplier == 0, the default pipeline (HarshMod / siege) is
+// used. Non-zero overrides the entire calculation.
+type TemporalBurnOverride struct {
+	Multiplier float32 // 0 = no override; 0.5 / 2.0 / etc. otherwise
+	Reason     string  // short tag for telemetry
+}
+
 // applyZoneTemporalPreBurn runs at the top of deliverBriefing, before
 // applyDailyBurn. It mutates e (state increments, in-memory only —
-// caller persists the relevant fields) and returns whether this
-// briefing's burn should be force-doubled regardless of HarshMod.
+// caller persists the relevant fields) and returns an optional
+// override on this morning's burn calculation.
 //
 // nextDay is the day-number we're rolling INTO (i.e. e.CurrentDay+1
 // at call site, since the briefing increments after burn).
-func applyZoneTemporalPreBurn(e *Expedition, nextDay int) (extraHarsh bool) {
+func applyZoneTemporalPreBurn(e *Expedition, nextDay int) TemporalBurnOverride {
 	switch e.ZoneID {
 	case ZoneSunkenTemple:
-		extraHarsh = sunkenTempleTemporalPreBurn(e, nextDay)
+		if sunkenTempleTemporalPreBurn(e, nextDay) {
+			return TemporalBurnOverride{Multiplier: 2.0, Reason: "sunken_temple_tidal"}
+		}
+	case ZoneFeywildCrossing:
+		return feywildTemporalPreBurn(e, nextDay)
 	}
-	return extraHarsh
+	return TemporalBurnOverride{}
 }
 
 // ManorResetCycleDays is the §7.2 reset cadence — non-boss rooms
@@ -102,6 +136,8 @@ func applyZoneTemporalPostRollover(e *Expedition) []string {
 		return manorTemporalPostRollover(e)
 	case ZoneUnderforge:
 		return underforgeTemporalPostRollover(e)
+	case ZoneFeywildCrossing:
+		return feywildTemporalPostRollover(e)
 	}
 	return nil
 }
@@ -237,6 +273,93 @@ func underforgeTemporalPostRollover(e *Expedition) []string {
 	return lines
 }
 
+// ─────────────────────────────────────────────────────────────────────
+// §7.4 — Feywild Crossing, Time Distortion
+// ─────────────────────────────────────────────────────────────────────
+
+// FeywildDistortion is the resolved effect of a daily 1d6 distortion
+// roll. Persisted to RegionState["feywild_today"] for the day so
+// downstream systems (extra wandering monster check at recap, time
+// loop signaling for the room engine) can read it.
+type FeywildDistortion string
+
+const (
+	FeywildDistortionNormal FeywildDistortion = "normal"
+	FeywildDistortionHalf   FeywildDistortion = "half"
+	FeywildDistortionDouble FeywildDistortion = "double"
+	FeywildDistortionLoop   FeywildDistortion = "loop"
+)
+
+// feywildRollFn is the test seam for the 1d6 distortion roll.
+var feywildRollFn = func() int { return 1 + randIntN(6) }
+
+// feywildResolveDistortion maps a 1d6 to the §7.4 effect bucket.
+func feywildResolveDistortion(d6 int) FeywildDistortion {
+	switch d6 {
+	case 1, 2:
+		return FeywildDistortionNormal
+	case 3, 4:
+		return FeywildDistortionHalf
+	case 5:
+		return FeywildDistortionDouble
+	default:
+		return FeywildDistortionLoop
+	}
+}
+
+// feywildTemporalPreBurn rolls today's distortion, persists it to
+// RegionState["feywild_today"], and returns the burn-override based on
+// the result. Boss-defeated suppresses entirely.
+func feywildTemporalPreBurn(e *Expedition, nextDay int) TemporalBurnOverride {
+	if e.BossDefeated {
+		return TemporalBurnOverride{}
+	}
+	d6 := feywildRollFn()
+	effect := feywildResolveDistortion(d6)
+	if e.RegionState == nil {
+		e.RegionState = map[string]any{}
+	}
+	e.RegionState["feywild_today"] = string(effect)
+	e.RegionState["feywild_today_d6"] = d6
+	_ = persistRegionState(e)
+
+	switch effect {
+	case FeywildDistortionHalf:
+		return TemporalBurnOverride{Multiplier: 0.5, Reason: "feywild_half_day"}
+	case FeywildDistortionDouble:
+		return TemporalBurnOverride{Multiplier: 2.0, Reason: "feywild_double_day"}
+	}
+	return TemporalBurnOverride{}
+}
+
+// feywildTemporalPostRollover narrates today's distortion. Normal-day
+// rolls produce no narration (they're the baseline).
+func feywildTemporalPostRollover(e *Expedition) []string {
+	if e.BossDefeated {
+		return nil
+	}
+	raw, _ := e.RegionState["feywild_today"].(string)
+	switch FeywildDistortion(raw) {
+	case FeywildDistortionHalf:
+		line := flavor.Pick(flavor.FeywildTimeDistortionHalf)
+		_ = appendExpeditionLog(e.ID, e.CurrentDay, "temporal",
+			"feywild distortion: half-day (0.5× burn)", line)
+		return []string{line}
+	case FeywildDistortionDouble:
+		line := flavor.Pick(flavor.FeywildTimeDistortionDouble)
+		_ = appendExpeditionLog(e.ID, e.CurrentDay, "temporal",
+			"feywild distortion: double-day (2× burn, extra wandering check pending)", line)
+		return []string{line}
+	case FeywildDistortionLoop:
+		line := flavor.Pick(flavor.FeywildTimeLoop)
+		_ = appendExpeditionLog(e.ID, e.CurrentDay, "temporal",
+			"feywild distortion: time loop (room re-enters with new enemies; loot already taken)",
+			line)
+		return []string{line}
+	}
+	return nil
+}
+
 // reduceUnderforgeHeat is called by processOvernightCamp when the
 // active camp is fortified (or base) in the Underforge — long rest
 // drops heat stacks by 2 per §7.3. Returns the new stack count.