diff --git a/src/buddy/companion.ts b/src/buddy/companion.ts
index 09c3838..a0fa798 100644
--- a/src/buddy/companion.ts
+++ b/src/buddy/companion.ts
@@ -116,18 +116,21 @@ export function rollWithSeed(seed: string): Roll {
   return rollFrom(mulberry32(hashString(seed)))
 }
 
+export function generateSeed(): string {
+  return `rehatch-${Date.now()}-${Math.random().toString(36).slice(2, 10)}`
+}
+
 export function companionUserId(): string {
   const config = getGlobalConfig()
   return config.oauthAccount?.accountUuid ?? config.userID ?? 'anon'
 }
 
-// Regenerate bones from userId, merge with stored soul. Bones never persist
-// so species renames and SPECIES-array edits can't break stored companions,
-// and editing config.companion can't fake a rarity.
+// Regenerate bones from seed or userId, merge with stored soul.
 export function getCompanion(): Companion | undefined {
   const stored = getGlobalConfig().companion
   if (!stored) return undefined
-  const { bones } = roll(companionUserId())
+  const seed = stored.seed ?? companionUserId()
+  const { bones } = rollWithSeed(seed)
   // bones last so stale bones fields in old-format configs get overridden
   return { ...stored, ...bones }
 }
diff --git a/src/buddy/types.ts b/src/buddy/types.ts
index 8f1c82a..46c53c7 100644
--- a/src/buddy/types.ts
+++ b/src/buddy/types.ts
@@ -111,6 +111,7 @@ export type CompanionBones = {
 export type CompanionSoul = {
   name: string
   personality: string
+  seed?: string
 }
 
 export type Companion = CompanionBones &
diff --git a/src/commands/buddy/buddy.ts b/src/commands/buddy/buddy.ts
index 2b371f2..134a3ff 100644
--- a/src/commands/buddy/buddy.ts
+++ b/src/commands/buddy/buddy.ts
@@ -1,8 +1,8 @@
 import {
   getCompanion,
-  roll,
+  rollWithSeed,
+  generateSeed,
   type Roll,
-  companionUserId,
 } from '../../buddy/companion.js'
 import {
   type StoredCompanion,
@@ -133,7 +133,8 @@ export const call: LocalCommandCall = async (args, _context) => {
       }
     }
 
-    const r = roll(companionUserId())
+    const seed = generateSeed()
+    const r = rollWithSeed(seed)
     const name = SPECIES_NAMES[r.bones.species] ?? 'Buddy'
     const personality =
       SPECIES_PERSONALITY[r.bones.species] ?? 'Mysterious and code-savvy.'
@@ -141,6 +142,7 @@ export const call: LocalCommandCall = async (args, _context) => {
     const stored: StoredCompanion = {
       name,
       personality,
+      seed,
       hatchedAt: Date.now(),
     }
 
@@ -212,7 +214,8 @@ export const call: LocalCommandCall = async (args, _context) => {
 
   // /buddy rehatch — re-roll a new companion (replaces existing)
   if (sub === 'rehatch') {
-    const r = roll(companionUserId())
+    const seed = generateSeed()
+    const r = rollWithSeed(seed)
     const name = SPECIES_NAMES[r.bones.species] ?? 'Buddy'
     const personality =
       SPECIES_PERSONALITY[r.bones.species] ?? 'Mysterious and code-savvy.'
@@ -220,6 +223,7 @@ export const call: LocalCommandCall = async (args, _context) => {
     const stored: StoredCompanion = {
       name,
       personality,
+      seed,
       hatchedAt: Date.now(),
     }