refactor(quartz): intern only on store reads, inject per-store interner

The previous commit interned at Event.fromJson, which is too early —
the deserializer can produce events with manipulated id fields that
don't match their content. Move interning to the post-validation
boundary: events are only canonicalised when read back from durable
storage, where they were valid when written.

- Revert Event.fromJson to plain OptimizedJsonMapper.fromJson.
- Revert ObservableEventStore.insert interning. Substituting the
  caller's event for a previously-cached one with the same id but
  potentially different sig was a write-side surprise; we leave the
  caller's instance alone.
- Intern at SQLiteStatement.toEvent (read deserialization).
- Intern at FsEventStore.readEvent (FS reads).

The interner is also now constructor-injected through every store
layer (SQLiteEventStore, EventStore, QueryBuilder, FsEventStore)
defaulting to EventInterner.Default. BaseDBTest gives each parallel
forEachDB store its own EventInterner — without this, parallel test
runs that sign "same id, different sig" events through the shared
Default would see the first run's sig leak across all DBs.

All 240 store + projection + interner tests pass.

https://claude.ai/code/session_01Jny85MTu1ynKgFBgysfWu5

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/core/Event.kt

@@ -67,7 +67,7 @@ open class Event(
     fun toJson(): String = OptimizedJsonMapper.toJson(this)
 
     companion object {
-        fun fromJson(json: String): Event = EventInterner.Default.intern(OptimizedJsonMapper.fromJson(json))
+        fun fromJson(json: String): Event = OptimizedJsonMapper.fromJson(json)
 
         fun fromJsonOrNull(json: String) =
             try {

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/store/sqlite/EventStore.kt

@@ -22,6 +22,7 @@ package com.vitorpamplona.quartz.nip01Core.store.sqlite
 
 import androidx.sqlite.driver.bundled.BundledSQLiteDriver
 import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.EventInterner
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.normalizeRelayUrl
@@ -36,8 +37,9 @@ class EventStore(
     dbName: String? = "events.db",
     val relay: NormalizedRelayUrl? = "wss://quartz.local/".normalizeRelayUrl(),
     val indexStrategy: IndexingStrategy = DefaultIndexingStrategy(),
+    val interner: EventInterner = EventInterner.Default,
 ) : IEventStore {
-    val store = SQLiteEventStore(BundledSQLiteDriver(), dbName, relay, indexStrategy)
+    val store = SQLiteEventStore(BundledSQLiteDriver(), dbName, relay, indexStrategy, interner = interner)
 
     override suspend fun insert(event: Event) = store.insertEvent(event)
 

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/store/sqlite/QueryBuilder.kt

@@ -23,6 +23,7 @@ package com.vitorpamplona.quartz.nip01Core.store.sqlite
 import androidx.sqlite.SQLiteConnection
 import androidx.sqlite.SQLiteStatement
 import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.EventInterner
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.Kind
 import com.vitorpamplona.quartz.nip01Core.core.OptimizedJsonMapper
@@ -35,6 +36,7 @@ class QueryBuilder(
     val fts: FullTextSearchModule,
     val hasher: (db: SQLiteConnection) -> TagNameValueHasher,
     val indexStrategy: IndexingStrategy,
+    val interner: EventInterner = EventInterner.Default,
 ) {
     // ------------
     // Main methods
@@ -232,16 +234,23 @@ class QueryBuilder(
         }
     }
 
-    private fun <T : Event> SQLiteStatement.toEvent() =
-        EventFactory.create<T>(
-            getText(0),
-            getText(1),
-            getLong(2),
-            getInt(3),
-            OptimizedJsonMapper.fromJsonToTagArray(getText(4)),
-            getText(5),
-            getText(6),
-        )
+    @Suppress("UNCHECKED_CAST")
+    private fun <T : Event> SQLiteStatement.toEvent(): T {
+        val event =
+            EventFactory.create<T>(
+                getText(0),
+                getText(1),
+                getLong(2),
+                getInt(3),
+                OptimizedJsonMapper.fromJsonToTagArray(getText(4)),
+                getText(5),
+                getText(6),
+            )
+        // Events read from durable storage were valid when written, so
+        // interning their reconstruction is safe. Multiple projections
+        // re-querying the same id end up sharing one Event instance.
+        return interner.intern(event) as T
+    }
 
     private fun SQLiteStatement.toRawEvent() =
         RawEvent(

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/store/sqlite/SQLiteEventStore.kt

@@ -25,6 +25,7 @@ import androidx.sqlite.SQLiteDriver
 import androidx.sqlite.SQLiteException
 import androidx.sqlite.driver.bundled.BundledSQLiteDriver
 import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.EventInterner
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.Kind
 import com.vitorpamplona.quartz.nip01Core.core.OptimizedJsonMapper
@@ -41,6 +42,7 @@ class SQLiteEventStore(
     val relay: NormalizedRelayUrl? = null,
     val indexStrategy: IndexingStrategy = DefaultIndexingStrategy(),
     val numReaders: Int = 4,
+    val interner: EventInterner = EventInterner.Default,
 ) {
     companion object {
         const val DATABASE_VERSION = 2
@@ -68,6 +70,7 @@ class SQLiteEventStore(
             fullTextSearchModule,
             seedModule::hasher,
             indexStrategy,
+            interner,
         )
 
     val modules =

quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/nip01Core/store/sqlite/BaseDBTest.kt

@@ -20,6 +20,7 @@
  */
 package com.vitorpamplona.quartz.nip01Core.store.sqlite
 
+import com.vitorpamplona.quartz.nip01Core.core.EventInterner
 import com.vitorpamplona.quartz.utils.Secp256k1Instance
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
@@ -63,6 +64,12 @@ open class BaseDBTest {
                             EventStore(
                                 dbName = null,
                                 indexStrategy = indexStrategy,
+                                // Each store gets its own interner so
+                                // parallel forEachDB runs don't share a
+                                // canonical Event for the same id —
+                                // tests sign with random sigs that
+                                // would otherwise cross-pollinate.
+                                interner = EventInterner(),
                             )
                     }
                 }

quartz/src/jvmMain/kotlin/com/vitorpamplona/quartz/nip01Core/store/fs/FsEventStore.kt

@@ -22,6 +22,7 @@ package com.vitorpamplona.quartz.nip01Core.store.fs
 
 import com.vitorpamplona.quartz.nip01Core.core.AddressableEvent
 import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.EventInterner
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.isAddressable
 import com.vitorpamplona.quartz.nip01Core.core.isEphemeral
@@ -75,6 +76,7 @@ open class FsEventStore(
      * verification re-canonicalises — so format is purely a UX choice.
      */
     private val eventToJson: (Event) -> String = Event::toJson,
+    private val interner: EventInterner = EventInterner.Default,
 ) : IEventStore {
     private val layout = FsLayout(root)
     private val hasher: TagNameValueHasher
@@ -508,7 +510,10 @@ open class FsEventStore(
         val p = layout.canonical(id)
         if (!p.exists()) return null
         return try {
-            Event.fromJson(p.readText())
+            // Events on disk were valid when written, so interning
+            // their reconstruction is safe and lets multiple readers
+            // of the same id share one Event instance.
+            interner.intern(Event.fromJson(p.readText()))
         } catch (_: java.nio.file.NoSuchFileException) {
             null
         }