From 799f44d59e5012d3aedbcadbffc7dc8a9f1d775c Mon Sep 17 00:00:00 2001
From: blippip69 <blippip69@users.noreply.github.com>
Date: Tue, 25 Aug 2026 20:30:43 +0300
Subject: [PATCH] fix: derive a distinct field seed per excursion (#3)

---
 lib/game.js   | 11 +++++++++--
 test/index.js | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/lib/game.js b/lib/game.js
index d781969..1975056 100644
--- a/lib/game.js
+++ b/lib/game.js
@@ -196,6 +196,7 @@ class Runa {
     this.dungeonReturn = null
     this.player = new Player()
     this.field = null
+    this.excursion = 0
     this.shop = null
     this.cursor = 0
     this.title = true
@@ -774,7 +775,10 @@ class Runa {
       this.pending = null
 
       if (location.kind === 'field') {
-        this.field = new Field({ script: this.scriptSource, player: this.player })
+        this.excursion++
+        const seed =
+          (this.excursion * 2654435761 + this.player.xp * 40503 + this.player.gold) >>> 0
+        this.field = new Field({ script: this.scriptSource, player: this.player, seed })
         this.field.player.x = clampNumber(location.x, 0, this.field.width - 1)
         this.field.player.y = clampNumber(location.y, 0, this.field.height - 1)
       } else {
@@ -1177,7 +1181,10 @@ class Runa {
     switch (action.kind) {
       case 'travel':
         if (action.to === 'field') {
-          this.field = new Field({ player: this.player })
+          this.excursion++
+          const seed =
+            (this.excursion * 2654435761 + this.player.xp * 40503 + this.player.gold) >>> 0
+          this.field = new Field({ player: this.player, seed })
           this.field.setScript(this.scriptSource)
           this.say('salis de la ciudad. pulsa t para volver cuando no estes peleando')
         } else if (action.to === 'dungeon') {
diff --git a/test/index.js b/test/index.js
index 44d13eb..2676c22 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1098,6 +1098,40 @@ test('hitbox combat stays on the field and advances on attack input', (t) => {
   )
 })
 
+test('two excursions are never the same field (#3)', (t) => {
+  const game = new Runa({ presence: false })
+  startGame(game)
+
+  const openField = () => {
+    const gateTile = { x: 0, y: 0 }
+    // find the '>' exit and step on it via placeAt + enter
+    for (let y = 0; y < MAPS.city.rows.length; y++) {
+      const x = MAPS.city.rows[y].indexOf('>')
+      if (x !== -1) {
+        gateTile.x = x
+        gateTile.y = y
+        break
+      }
+    }
+    game.walker.placeAt('city', gateTile.x, gateTile.y)
+    press(game, 'e')
+  }
+
+  openField()
+  t.ok(game.field, 'first excursion opens the field')
+  const first = game.field.seed
+
+  press(game, 't')
+  t.absent(game.field, 't closes the excursion')
+  game.player.gold += 7
+
+  openField()
+  t.ok(game.field, 'second excursion opens a fresh field')
+  const second = game.field.seed
+
+  t.not(first, second, 'the seed differs between excursions')
+})
+
 test('t returns from the field to the city outside combat', (t) => {
   const game = new Runa({ presence: false })
   startGame(game)