adventure: T6 Inversion Stitch (Seamstress) + boss re-strengthen (P8)

Second in-combat Layer-2 mechanic, reusing Amendment's round-end seam. In the
Seamstress's phase 2 (<=35% HP) the room sews inside-out in a repeating
warn(1)->sting(2) cadence, telegraphed one round ahead: during a pulse player
heals (self + ally) invert to damage, floored at 1 HP. State
inversionActive/inversionTelegraph round-trips through CombatStatuses so a
suspend/resume can't drop or double a pulse.

Sim surfaced that unplace is reach-bound (only ~37% reach the boss, then cleared
her ~98%), so the mechanic alone is sub-noise. Re-strengthened the Seamstress,
the weakest T6 boss (over-softened by P7 for a zone lift that never came):
HP 385->460, Atk 39->45, Needle Rain proc 0.40->0.45. Sim-validated at
fighter zone 37.5% (in range), and a real boss fight now instead of a victory lap.

Claude-Session: https://claude.ai/code/session_0156WqjgsbmSY2U8eQ3Kkb1s

internal/plugin/combat_engine.go

@@ -452,6 +452,16 @@ type combatState struct {
 	enemyRewindHP   int
 	enemyRewindUsed bool
 
+	// Inversion Stitch (T6 Seamstress) — an in-combat Layer-2 hook resolved at
+	// round end by applyBossInCombatRoundEnd, live only in the boss's phase 2.
+	// inversionActive is the number of rounds the room stays sewn inside-out
+	// (heals sting instead of mend, gated in stepPlayerActionEffect); it counts
+	// down one per round end. inversionTelegraph warns the round before a pulse
+	// activates, so a player who watches the tell can hold their heals. Both
+	// round-trip through CombatStatuses; zero/false for every non-Seamstress fight.
+	inversionActive    int
+	inversionTelegraph bool
+
 	round  int
 	events []CombatEvent
 

internal/plugin/combat_narrative.go

@@ -337,6 +337,12 @@ func renderEvent(e CombatEvent, playerName, enemyName string, result CombatResul
 		return pickRand(narrativeAmendmentRewind)
 	case "midnight_toll":
 		return fmt.Sprintf(pickRand(narrativeMidnightToll), e.Damage)
+	case "inversion_telegraph":
+		return pickRand(narrativeInversionTelegraph)
+	case "inversion_stitch":
+		return pickRand(narrativeInversionStitch)
+	case "heal_inverted":
+		return fmt.Sprintf(pickRand(narrativeHealInverted), e.Damage)
 	case "stat_drain":
 		return fmt.Sprintf(pickRand(narrativeStatDrain), e.Damage)
 	case "debuff":
@@ -792,6 +798,27 @@ var narrativeMidnightToll = []string{
 	"🔔 The hour is nearly spent, and so is its patience; each blow lands with more weight now. (+%d attack)",
 }
 
+// narrativeInversionTelegraph fires one round before an Inversion Stitch pulse —
+// the Seamstress's tell. It reads as a warning so a player learns to hold heals.
+var narrativeInversionTelegraph = []string{
+	"🧵 The Seamstress draws a thread taut and the room *shivers* — walls flexing toward inside-out. Whatever you were about to mend, hold it. (next round, healing turns against you)",
+	"🧵 A seam in the air puckers. The geometry is about to flip; a cure cast into it will run backward. (inversion incoming next round)",
+}
+
+// narrativeInversionStitch fires when a pulse activates — the room is sewn
+// inside-out and healing now wounds for the pulse's duration.
+var narrativeInversionStitch = []string{
+	"🧵 The stitch pulls through. The room is inside-out now — for a moment, to heal is to hurt.",
+	"🧵 Everything turns wrong-way-round. Mending and wounding have swapped ends of the needle.",
+}
+
+// narrativeHealInverted fires each time a heal lands during an active pulse: the
+// cure runs backward and stings instead. Teaches the mechanic on the spot.
+var narrativeHealInverted = []string{
+	"🧵 The heal runs backward through the inverted room — the cure opens the wound it meant to close. (%d damage)",
+	"🧵 Healing turns against its target in the sewn-inside-out air; the mend lands as a sting. (%d damage)",
+}
+
 var narrativeStatDrain = []string{
 	"🩸 The enemy saps your strength — your swings feel heavier, weaker. (-%d hit damage)",
 	"🩸 Something drains out of your limbs. Your hits won't bite as deep now. (-%d damage)",

internal/plugin/combat_session.go

@@ -243,6 +243,16 @@ type CombatStatuses struct {
 	// existing EnemyAtkBuff, so it needs no field of its own.
 	EnemyRewindHP   int  `json:"enemy_rewind_hp,omitempty"`
 	EnemyRewindUsed bool `json:"enemy_rewind_used,omitempty"`
+
+	// Inversion Stitch (Tier-6 postgame, The Seamstress). An in-combat Layer-2
+	// hook resolved at round end (applyBossInCombatRoundEnd), live only in the
+	// boss's phase 2. InversionActive is the rounds-remaining of the inside-out
+	// pulse during which player heals sting instead of mend (gated in
+	// stepPlayerActionEffect); InversionTelegraph is the one-round warning before
+	// a pulse activates. Both round-trip through combatState so a suspend/resume
+	// can't lose or replay a pulse mid-fight. Zero/false for every other enemy.
+	InversionActive    int  `json:"inversion_active,omitempty"`
+	InversionTelegraph bool `json:"inversion_telegraph,omitempty"`
 }
 
 // applyBuffDelta folds one resolved buff (the result of a !cast / !consume

internal/plugin/combat_turn_engine.go

@@ -373,6 +373,9 @@ func resumeTurnEngine(sess *CombatSession, players []*Combatant, enemy *Combatan
 		// Amendment (T6 Custodian) — round-3 snapshot + once-only rewind.
 		enemyRewindHP:   sess.Statuses.EnemyRewindHP,
 		enemyRewindUsed: sess.Statuses.EnemyRewindUsed,
+		// Inversion Stitch (T6 Seamstress) — phase-2 heal-inverting pulses.
+		inversionActive:    sess.Statuses.InversionActive,
+		inversionTelegraph: sess.Statuses.InversionTelegraph,
 		rng:                rng,
 	}
 	order := turnOrder(sess, sess.Round, players, enemy)
@@ -573,11 +576,23 @@ func (te *turnEngine) stepPlayerActionEffect(eff *turnActionEffect) {
 		st.enemyHP = max(0, st.enemyHP-enemyDmg)
 	}
 	if eff.PlayerHeal > 0 {
+		if st.inversionActive > 0 {
+			// Inversion Stitch (T6 Seamstress phase 2): the room is sewn inside-out,
+			// so the cure lands as a wound. Floored at 1 so a player is never killed
+			// by their own heal — the Seamstress's own blows do the finishing; the
+			// sting just denies the sustain and softens the seat for them.
+			st.playerHP = max(1, st.playerHP-eff.PlayerHeal)
+			st.events = append(st.events, CombatEvent{
+				Round: st.round, Phase: turnCombatPhase.Name, Actor: "enemy", Action: "heal_inverted",
+				Damage: eff.PlayerHeal, PlayerHP: st.playerHP, EnemyHP: st.enemyHP,
+			})
+		} else {
 			// Respect any max_hp_drain monster ability — a drained player can't be
 			// healed back past the lowered ceiling.
 			hpCap := max(1, st.hpMax-st.maxHPDrain)
 			st.playerHP = min(hpCap, st.playerHP+eff.PlayerHeal)
 		}
+	}
 	// §1 — heal somebody else. The caster's cursor stays where it is; only the
 	// target's HP moves.
 	//
@@ -587,6 +602,18 @@ func (te *turnEngine) stepPlayerActionEffect(eff *turnActionEffect) {
 	// path depends on. Healing keeps people up; it does not bring them back.
 	if eff.AllyHeal > 0 && eff.AllySeat >= 0 && eff.AllySeat < len(st.actors) {
 		if tgt := st.actors[eff.AllySeat]; tgt.playerHP > 0 {
+			if st.inversionActive > 0 {
+				// Inversion Stitch: the ally-heal wounds the friend it was meant to
+				// mend. Floored at 1 like the self-heal sting above — the sting denies
+				// the sustain, it does not kill.
+				before := tgt.playerHP
+				tgt.playerHP = max(1, tgt.playerHP-eff.AllyHeal)
+				st.events = append(st.events, CombatEvent{
+					Round: st.round, Phase: turnCombatPhase.Name, Actor: "enemy", Action: "heal_inverted",
+					Damage: before - tgt.playerHP, PlayerHP: tgt.playerHP, EnemyHP: st.enemyHP,
+					Seat: eff.AllySeat, Desc: eff.Label,
+				})
+			} else {
 				cap := max(1, tgt.hpMax-tgt.maxHPDrain)
 				before := tgt.playerHP
 				tgt.playerHP = min(cap, tgt.playerHP+eff.AllyHeal)
@@ -597,6 +624,7 @@ func (te *turnEngine) stepPlayerActionEffect(eff *turnActionEffect) {
 				})
 			}
 		}
+	}
 	// Arm / replace the concentration aura. A new concentration cast overwrites
 	// the old one (5e: one concentration at a time); non-concentration casts
 	// leave any running aura alone.
@@ -952,6 +980,8 @@ func (te *turnEngine) commit() {
 	s.EnemyAtkBuff = st.enemyAtkBuff
 	s.EnemyRewindHP = st.enemyRewindHP
 	s.EnemyRewindUsed = st.enemyRewindUsed
+	s.InversionActive = st.inversionActive
+	s.InversionTelegraph = st.inversionTelegraph
 
 	te.sess.TurnLog = append(te.sess.TurnLog, st.events...)
 }

internal/plugin/postgame_bestiary.go

@@ -167,9 +167,9 @@ var _ = func() bool {
 		},
 		"boss_seamstress": {
 			ID: "boss_seamstress", Name: "The Seamstress",
-			CR: 27, HP: 385, AC: 21, Attack: 39, AttackBonus: 12, Speed: 14,
+			CR: 27, HP: 460, AC: 21, Attack: 45, AttackBonus: 12, Speed: 14,
 			BlockRate: 0.15,
-			Ability:   &MonsterAbility{Name: "Needle Rain", Phase: "decisive", ProcChance: 0.40, Effect: "aoe"},
+			Ability:   &MonsterAbility{Name: "Needle Rain", Phase: "decisive", ProcChance: 0.45, Effect: "aoe"},
 			XPValue:   100000,
 			Notes:     "Unplace boss. A corrupted celestial sewing herself into the tear; half of her is on the other side. Phase 2 below 35% HP. (Layer 2: Inversion Stitch — healing and damage swap direction on her in telegraphed pulses.)",
 		},

internal/plugin/postgame_boss_hooks.go

@@ -228,6 +228,8 @@ func applyBossInCombatRoundEnd(st *combatState, bossID string, enemyMaxHP int) {
 	switch bossID {
 	case "boss_custodian":
 		applyAmendment(st, enemyMaxHP)
+	case "boss_seamstress":
+		applyInversionStitch(st, enemyMaxHP)
 	}
 }
 
@@ -261,3 +263,72 @@ func applyAmendment(st *combatState, enemyMaxHP int) {
 		})
 	}
 }
+
+// ── Inversion Stitch — The Seamstress (The Unplace) ──────────────────────────
+//
+// The Seamstress is sewing the tear shut from the inside, and once she's far
+// enough into the work (phase 2) she starts turning the room inside-out around
+// the party: for a two-round pulse, healing runs the wrong direction — every
+// cure lands as a wound (gated in stepPlayerActionEffect, floored at 1 HP so a
+// player is never killed by their own healer, only softened for the Seamstress's
+// own blows to finish). The catch is that she can't invert the room without a
+// visible tell: each pulse is telegraphed one full round ahead, so a player who
+// reads it holds their heals and waits it out. The autopilot that drives the sim
+// does not read tells — so the headless sweep sees the mechanic at its harshest,
+// the way an undisciplined party would, and a real player who respects the
+// warning fares better. That gap IS the difficulty lever, the same way the Greed
+// Tax and the Phylactery Verses are prod-only player-agency levers.
+//
+// It is the second in-combat Layer-2 mechanic, so it rides the same round-end
+// seam Amendment opened. Its state (inversionActive countdown + inversionTelegraph
+// warning) round-trips through CombatStatuses so a suspend/resume can't drop or
+// double a pulse. A no-op outside the Seamstress's phase 2.
+const (
+	// seamstressPhaseTwoFrac must track The Seamstress's PhaseTwoAt in
+	// postgame_zone_defs.go (0.35): the inversion only starts once she is sewn
+	// deep enough into the tear. Kept local for the same reason as
+	// custodianPhaseTwoFrac — the round-end hook resolves off the session, not the
+	// ZoneDefinition, so the threshold isn't otherwise in reach here.
+	seamstressPhaseTwoFrac = 0.35
+
+	// inversionPulseRounds is how many rounds each inside-out pulse lasts once it
+	// activates (heals sting for this many player-rounds).
+	inversionPulseRounds = 2
+)
+
+// applyInversionStitch drives the Seamstress's phase-2 inversion cadence at round
+// end: telegraph a pulse one round ahead, activate it for inversionPulseRounds,
+// then re-telegraph the next — giving a repeating warn(1) → sting(2) rhythm the
+// player can play around. No-op until the boss is in phase 2.
+func applyInversionStitch(st *combatState, enemyMaxHP int) {
+	// Layer-1 fight until the Seamstress is sewn into her own phase 2.
+	phaseTwo := int(seamstressPhaseTwoFrac * float64(enemyMaxHP))
+	if st.enemyHP > phaseTwo {
+		return
+	}
+	// An active pulse counts down one round per round end. While it stays above
+	// zero the next round's heals still sting; when it lapses this round, fall
+	// through so a fresh telegraph is scheduled immediately.
+	if st.inversionActive > 0 {
+		st.inversionActive--
+		if st.inversionActive > 0 {
+			return
+		}
+	}
+	// A telegraphed pulse activates: the room turns inside-out for the pulse.
+	if st.inversionTelegraph {
+		st.inversionActive = inversionPulseRounds
+		st.inversionTelegraph = false
+		st.events = append(st.events, CombatEvent{
+			Round: st.round, Phase: CombatPhaseRoundEnd, Actor: "enemy", Action: "inversion_stitch",
+			PlayerHP: st.playerHP, EnemyHP: st.enemyHP,
+		})
+		return
+	}
+	// Otherwise warn: the next round's pulse is one round out.
+	st.inversionTelegraph = true
+	st.events = append(st.events, CombatEvent{
+		Round: st.round, Phase: CombatPhaseRoundEnd, Actor: "enemy", Action: "inversion_telegraph",
+		PlayerHP: st.playerHP, EnemyHP: st.enemyHP,
+	})
+}

internal/plugin/postgame_boss_hooks_test.go

@@ -1,6 +1,9 @@
 package plugin
 
-import "testing"
+import (
+	"strings"
+	"testing"
+)
 
 func TestGreedTaxAttack(t *testing.T) {
 	cases := []struct {
@@ -337,6 +340,148 @@ func TestApplyBossInCombatRoundEnd_DispatchesOnlyCustodian(t *testing.T) {
 	}
 }
 
+// ── Inversion Stitch (Seamstress) ────────────────────────────────────────────
+
+// seamstressState builds a fully-formed combatState (embedded actor + roster) so
+// the event helpers that read st.playerHP resolve — a bare struct-literal state
+// has a nil actor cursor.
+func seamstressState(t *testing.T, enemyHP, enemyMaxHP int) *combatState {
+	t.Helper()
+	sess := turnSession(CombatPhaseRoundEnd, 10000, enemyHP)
+	sess.EnemyID = "boss_seamstress"
+	p := basePlayer()
+	e := baseEnemy()
+	e.Stats.MaxHP = enemyMaxHP
+	te := resumeTurnEngine(sess, []*Combatant{&p}, &e, combatSessionStepRNG(sess, enemySeat))
+	te.st.enemyHP = enemyHP
+	return te.st
+}
+
+func TestApplyInversionStitch_NoOpAbovePhaseTwo(t *testing.T) {
+	// Above the 0.35*500=175 phase-two line the room stays right-side-out.
+	st := seamstressState(t, 300, 500)
+	applyInversionStitch(st, 500)
+	if st.inversionTelegraph || st.inversionActive != 0 || len(st.events) != 0 {
+		t.Errorf("above phase two: telegraph=%v active=%d events=%d, want all zero",
+			st.inversionTelegraph, st.inversionActive, len(st.events))
+	}
+}
+
+func TestApplyInversionStitch_Cadence(t *testing.T) {
+	// Below the phase-two line the room cycles warn(1) → sting(pulse) → warn(1)…
+	st := seamstressState(t, 150, 500) // 150 < 0.35*500 = 175
+
+	// Round end 1: no pulse yet, so telegraph the first one.
+	applyInversionStitch(st, 500)
+	if !st.inversionTelegraph || st.inversionActive != 0 {
+		t.Fatalf("after warn: telegraph=%v active=%d, want telegraph=true active=0",
+			st.inversionTelegraph, st.inversionActive)
+	}
+	if countEvents(st.events, "inversion_telegraph") != 1 {
+		t.Fatalf("telegraph events = %d, want 1", countEvents(st.events, "inversion_telegraph"))
+	}
+
+	// Round end 2: the telegraphed pulse activates for its full duration.
+	applyInversionStitch(st, 500)
+	if st.inversionActive != inversionPulseRounds || st.inversionTelegraph {
+		t.Fatalf("after activate: active=%d telegraph=%v, want active=%d telegraph=false",
+			st.inversionActive, st.inversionTelegraph, inversionPulseRounds)
+	}
+	if countEvents(st.events, "inversion_stitch") != 1 {
+		t.Fatalf("stitch events = %d, want 1", countEvents(st.events, "inversion_stitch"))
+	}
+
+	// The pulse counts down one round per round end, staying active until it lapses.
+	for r := inversionPulseRounds - 1; r >= 1; r-- {
+		applyInversionStitch(st, 500)
+		if st.inversionActive != r {
+			t.Fatalf("mid-pulse active = %d, want %d", st.inversionActive, r)
+		}
+	}
+
+	// The round the pulse lapses (active 1→0) a fresh warn is scheduled in the
+	// same round end — the repeating rhythm, never two silent rounds in a row.
+	applyInversionStitch(st, 500)
+	if st.inversionActive != 0 || !st.inversionTelegraph {
+		t.Fatalf("after pulse: active=%d telegraph=%v, want active=0 telegraph=true",
+			st.inversionActive, st.inversionTelegraph)
+	}
+	if countEvents(st.events, "inversion_telegraph") != 2 {
+		t.Fatalf("telegraph events = %d, want 2 (the next pulse warned)",
+			countEvents(st.events, "inversion_telegraph"))
+	}
+}
+
+func TestApplyBossInCombatRoundEnd_DispatchesSeamstress(t *testing.T) {
+	// A non-Seamstress boss at a phase-two HP is untouched.
+	st := seamstressState(t, 150, 500)
+	applyBossInCombatRoundEnd(st, "boss_aurvandryx", 500)
+	if st.inversionTelegraph || len(st.events) != 0 {
+		t.Errorf("non-Seamstress boss triggered inversion (telegraph=%v events=%d)",
+			st.inversionTelegraph, len(st.events))
+	}
+	// The Seamstress id resolves the hook.
+	applyBossInCombatRoundEnd(st, "boss_seamstress", 500)
+	if !st.inversionTelegraph {
+		t.Error("boss_seamstress did not schedule the inversion telegraph")
+	}
+}
+
+// TestInversionStitch_HealsSting drives a real round with an active pulse seeded
+// and confirms both the self-heal and the ally-heal land as wounds, floored at 1.
+func TestInversionStitch_HealsSting(t *testing.T) {
+	setupEmptyTestDB(t)
+	p := &AdventurePlugin{}
+
+	t.Run("ally heal stings the friend", func(t *testing.T) {
+		sess := startAllyHealFight(t, p, 50) // friend hurt to 50/100
+		sess.Statuses.InversionActive = 1    // room is inside-out this round
+		healer, friend := basePlayer(), basePlayer()
+		ct := &combatTurn{sess: sess, players: []*Combatant{&healer, &friend},
+			enemy: &Combatant{Name: "dummy", Stats: CombatStats{MaxHP: 800, AC: 10, Attack: 1, AttackBonus: 1}},
+			seat:  0, uid: healerID(strings.ReplaceAll(t.Name(), "/", "_"))}
+		before := sess.seatHP(1)
+
+		events, err := p.driveCombatRound(ct, PlayerAction{Kind: ActionCast,
+			Effect: &turnActionEffect{Label: "Cure", Action: "spell_cast", AllyHeal: 30, AllySeat: 1}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if got := sess.seatHP(1); got >= before {
+			t.Errorf("friend HP = %d (was %d) — an inverted heal must wound, not mend", got, before)
+		}
+		if countEvents(events, "heal_inverted") != 1 {
+			t.Errorf("heal_inverted events = %d, want 1", countEvents(events, "heal_inverted"))
+		}
+	})
+
+	t.Run("self heal stings the acting seat, floored at 1", func(t *testing.T) {
+		// A self-heal (PlayerHeal, no AllySeat) lands on whichever seat is acting;
+		// assert the inversion fired (heal_inverted) and no seat was driven to 0 —
+		// the sting denies sustain, it never kills.
+		sess := startAllyHealFight(t, p, 100)
+		sess.Statuses.InversionActive = 1
+		healer, friend := basePlayer(), basePlayer()
+		ct := &combatTurn{sess: sess, players: []*Combatant{&healer, &friend},
+			enemy: &Combatant{Name: "dummy", Stats: CombatStats{MaxHP: 800, AC: 10, Attack: 1, AttackBonus: 1}},
+			seat:  0, uid: healerID(strings.ReplaceAll(t.Name(), "/", "_"))}
+
+		events, err := p.driveCombatRound(ct, PlayerAction{Kind: ActionCast,
+			Effect: &turnActionEffect{Label: "Cure Self", Action: "spell_cast", PlayerHeal: 30}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if countEvents(events, "heal_inverted") != 1 {
+			t.Errorf("heal_inverted events = %d, want 1 — the self-heal did not invert", countEvents(events, "heal_inverted"))
+		}
+		for seat := 0; seat < 2; seat++ {
+			if got := sess.seatHP(seat); got < 1 {
+				t.Errorf("seat %d HP = %d — the sting must floor at 1, never kill", seat, got)
+			}
+		}
+	})
+}
+
 func TestTurnEngine_AmendmentRoundTrips(t *testing.T) {
 	// Drive a real Custodian round-end and confirm the once-only rewind is
 	// captured through CombatStatuses (a suspend/resume can't replay it).
@@ -364,3 +509,26 @@ func TestTurnEngine_AmendmentRoundTrips(t *testing.T) {
 		t.Errorf("amendment_rewind events = %d, want 1", countEvents(sess.TurnLog, "amendment_rewind"))
 	}
 }
+
+func TestTurnEngine_InversionRoundTrips(t *testing.T) {
+	// Drive a real Seamstress round-end in phase 2 and confirm the scheduled
+	// telegraph persists through CombatStatuses (a suspend/resume keeps the cadence).
+	sess := turnSession(CombatPhaseRoundEnd, 10000, 150) // 150 < 0.35*500 = 175
+	sess.EnemyID = "boss_seamstress"
+	sess.EnemyHPMax = 500
+	p := basePlayer()
+	e := baseEnemy()
+	e.Stats.MaxHP = 500
+	te := resumeTurnEngine(sess, []*Combatant{&p}, &e, combatSessionStepRNG(sess, enemySeat))
+	if _, err := te.step(PlayerAction{}); err != nil {
+		t.Fatal(err)
+	}
+	te.commit()
+
+	if !sess.Statuses.InversionTelegraph {
+		t.Error("InversionTelegraph did not persist through commit")
+	}
+	if countEvents(sess.TurnLog, "inversion_telegraph") != 1 {
+		t.Errorf("inversion_telegraph events = %d, want 1", countEvents(sess.TurnLog, "inversion_telegraph"))
+	}
+}