fix: drop the "Mock Podcast" kind:10154 spam flood before consuming

Someone is flooding thousands of identical mock NIP-F4 show-metadata events.
They share an exact fingerprint — title "Mock Podcast", description and content
both "Headless test feed" — so match that and refuse to cache them.

- PodcastMetadataEvent.isMockSpam() encodes the fingerprint (all three fields
  must match, so a real show sharing one field is never flagged); unit-tested.
- LocalCache's PodcastMetadataEvent consume branch returns without storing when
  it matches, so the spam never reaches the cache, feeds, search, or the merged
  podcast list.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JGa1EM5KWyDo1o5Yr6sS18

amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt

@@ -3754,7 +3754,12 @@ object LocalCache : ILocalCache, ICacheProvider {
                 }
 
                 is PodcastMetadataEvent -> {
-                    consumeBaseReplaceable(event, relay, wasVerified)
+                    // Drop the known "Mock Podcast" spam flood instead of caching thousands of them.
+                    if (event.isMockSpam()) {
+                        false
+                    } else {
+                        consumeBaseReplaceable(event, relay, wasVerified)
+                    }
                 }
 
                 is AuthoredPodcastsEvent -> {

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nipF4Podcasts/metadata/PodcastMetadataEvent.kt

@@ -83,9 +83,22 @@ class PodcastMetadataEvent(
      */
     fun claimedAuthors() = tags.mapNotNull(AuthorTag::parse)
 
+    /**
+     * Fingerprint of a known spam flood — thousands of identical headless-test "Mock Podcast"
+     * shows. Their structure is exactly `title="Mock Podcast"`, `description="Headless test feed"`,
+     * `content="Headless test feed"`. Matched so the client can drop them before consuming.
+     */
+    fun isMockSpam(): Boolean =
+        content == MOCK_SPAM_CONTENT &&
+            title() == MOCK_SPAM_TITLE &&
+            description() == MOCK_SPAM_CONTENT
+
     companion object {
         const val KIND = 10154
 
+        private const val MOCK_SPAM_TITLE = "Mock Podcast"
+        private const val MOCK_SPAM_CONTENT = "Headless test feed"
+
         fun createAddress(pubKey: HexKey) = Address(KIND, pubKey, FIXED_D_TAG)
 
         fun createAddressATag(pubKey: HexKey) = ATag(KIND, pubKey, FIXED_D_TAG, null)

quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/nipF4Podcasts/PodcastMockSpamTest.kt

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.nipF4Podcasts
+
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nipF4Podcasts.metadata.PodcastMetadataEvent
+import kotlin.test.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+/** Verifies the fingerprint used to drop the "Mock Podcast" spam flood, and that it spares real shows. */
+class PodcastMockSpamTest {
+    private fun event(
+        title: String?,
+        description: String?,
+        content: String,
+    ): PodcastMetadataEvent {
+        val tags =
+            buildList {
+                title?.let { add(arrayOf("title", it)) }
+                description?.let { add(arrayOf("description", it)) }
+            }.toTypedArray()
+        return PodcastMetadataEvent(EMPTY_ID, EMPTY_ID, 0, tags, content, EMPTY_ID)
+    }
+
+    @Test
+    fun `the exact mock spam structure matches`() {
+        assertTrue(event("Mock Podcast", "Headless test feed", "Headless test feed").isMockSpam())
+    }
+
+    @Test
+    fun `real shows are not flagged`() {
+        // A genuine show that happens to share none of the three fields.
+        assertFalse(event("My Real Podcast", "A show about things", "Welcome!").isMockSpam())
+        // Same title only — not enough.
+        assertFalse(event("Mock Podcast", "A different description", "Real content").isMockSpam())
+        // Same content only — not enough.
+        assertFalse(event("Another Show", "Another desc", "Headless test feed").isMockSpam())
+        // Missing tags entirely.
+        assertFalse(event(null, null, "Headless test feed").isMockSpam())
+    }
+
+    companion object {
+        private val EMPTY_ID: HexKey = "0".repeat(64)
+    }
+}