feat: implement full NIP-52 calendar spec compliance

- CalendarDateSlotEvent (31922): Add title, summary, image, geohash,
  hashtags, participants, references, multiple locations accessors and
  build() method with DSL builder pattern
- CalendarTimeSlotEvent (31923): Fix timezone bug (startTzId/endTzId
  were parsed as Long instead of String), add all accessors like
  DateSlot, rename startTmz/endTmz to startTzId/endTzId, add build()
- CalendarRSVPEvent (31925): Remove incorrect location/start/end
  accessors (not in spec), add status/freebusy/calendarEventAddress/
  calendarEventId/calendarEventAuthor accessors, update from outdated
  L/l label format to current status/fb tag format, add build()
- CalendarEvent (31924): Add title and calendarEventAddresses accessors,
  add build() method
- Create NIP-52 tag classes: LocationTag, RSVPStatusTag (with enum),
  FreeBusyTag (with enum)
- Create TagArrayBuilderExt.kt with DSL builder extensions for all
  four calendar event types

https://claude.ai/code/session_01UMXgE3tNftmqNZqcYwF2kL

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip52Calendar/CalendarDateSlotEvent.kt

@@ -23,10 +23,22 @@ package com.vitorpamplona.quartz.nip52Calendar
 import androidx.compose.runtime.Immutable
 import com.vitorpamplona.quartz.nip01Core.core.BaseAddressableEvent
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.core.TagArrayBuilder
 import com.vitorpamplona.quartz.nip01Core.core.firstTagValue
-import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
+import com.vitorpamplona.quartz.nip01Core.signers.eventTemplate
-import com.vitorpamplona.quartz.nip31Alts.AltTag
+import com.vitorpamplona.quartz.nip01Core.tags.dTag.dTag
+import com.vitorpamplona.quartz.nip01Core.tags.geohash.GeoHashTag
+import com.vitorpamplona.quartz.nip01Core.tags.hashtags.hashtags
+import com.vitorpamplona.quartz.nip01Core.tags.people.PTag
+import com.vitorpamplona.quartz.nip01Core.tags.references.references
+import com.vitorpamplona.quartz.nip23LongContent.tags.ImageTag
+import com.vitorpamplona.quartz.nip23LongContent.tags.SummaryTag
+import com.vitorpamplona.quartz.nip23LongContent.tags.TitleTag
+import com.vitorpamplona.quartz.nip31Alts.alt
+import com.vitorpamplona.quartz.nip52Calendar.tags.LocationTag
 import com.vitorpamplona.quartz.utils.TimeUtils
+import kotlin.uuid.ExperimentalUuidApi
+import kotlin.uuid.Uuid
 
 @Immutable
 class CalendarDateSlotEvent(
@@ -37,25 +49,48 @@ class CalendarDateSlotEvent(
     content: String,
     sig: HexKey,
 ) : BaseAddressableEvent(id, pubKey, createdAt, KIND, tags, content, sig) {
-    fun location() = tags.firstTagValue("location")
+    fun title() = tags.firstNotNullOfOrNull(TitleTag::parse)
+
+    fun location() = tags.firstNotNullOfOrNull(LocationTag::parse)
+
+    fun locations() = tags.mapNotNull(LocationTag::parse)
 
     fun start() = tags.firstTagValue("start")
 
     fun end() = tags.firstTagValue("end")
 
-    //  ["start", "<YYYY-MM-DD>"],
+    fun summary() = tags.firstNotNullOfOrNull(SummaryTag::parse)
-    //  ["end", "<YYYY-MM-DD>"],
+
+    fun image() = tags.firstNotNullOfOrNull(ImageTag::parse)
+
+    fun geohash() = tags.firstNotNullOfOrNull(GeoHashTag::parse)
+
+    fun hashtags() = tags.hashtags()
+
+    fun participants() = tags.mapNotNull(PTag::parse)
+
+    fun references() = tags.references()
 
     companion object {
         const val KIND = 31922
         const val ALT = "Full-day calendar event"
 
-        suspend fun create(
+        @OptIn(ExperimentalUuidApi::class)
-            signer: NostrSigner,
+        fun build(
+            title: String,
+            start: String,
+            content: String = "",
+            end: String? = null,
+            dTag: String = Uuid.random().toString(),
             createdAt: Long = TimeUtils.now(),
-        ): CalendarDateSlotEvent {
+            initializer: TagArrayBuilder<CalendarDateSlotEvent>.() -> Unit = {},
-            val tags = arrayOf(AltTag.assemble(ALT))
+        ) = eventTemplate(KIND, content, createdAt) {
-            return signer.sign(createdAt, KIND, tags, "")
+            dTag(dTag)
+            title(title)
+            startDate(start)
+            end?.let { endDate(it) }
+            alt(ALT)
+            initializer()
         }
     }
 }

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip52Calendar/CalendarEvent.kt

@@ -23,9 +23,15 @@ package com.vitorpamplona.quartz.nip52Calendar
 import androidx.compose.runtime.Immutable
 import com.vitorpamplona.quartz.nip01Core.core.BaseAddressableEvent
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
-import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
+import com.vitorpamplona.quartz.nip01Core.core.TagArrayBuilder
-import com.vitorpamplona.quartz.nip31Alts.AltTag
+import com.vitorpamplona.quartz.nip01Core.signers.eventTemplate
+import com.vitorpamplona.quartz.nip01Core.tags.aTag.taggedAddresses
+import com.vitorpamplona.quartz.nip01Core.tags.dTag.dTag
+import com.vitorpamplona.quartz.nip23LongContent.tags.TitleTag
+import com.vitorpamplona.quartz.nip31Alts.alt
 import com.vitorpamplona.quartz.utils.TimeUtils
+import kotlin.uuid.ExperimentalUuidApi
+import kotlin.uuid.Uuid
 
 @Immutable
 class CalendarEvent(
@@ -36,16 +42,26 @@ class CalendarEvent(
     content: String,
     sig: HexKey,
 ) : BaseAddressableEvent(id, pubKey, createdAt, KIND, tags, content, sig) {
+    fun title() = tags.firstNotNullOfOrNull(TitleTag::parse)
+
+    fun calendarEventAddresses() = taggedAddresses()
+
     companion object {
         const val KIND = 31924
         const val ALT = "Calendar"
 
-        suspend fun create(
+        @OptIn(ExperimentalUuidApi::class)
-            signer: NostrSigner,
+        fun build(
+            title: String,
+            content: String = "",
+            dTag: String = Uuid.random().toString(),
             createdAt: Long = TimeUtils.now(),
-        ): CalendarEvent {
+            initializer: TagArrayBuilder<CalendarEvent>.() -> Unit = {},
-            val tags = arrayOf(AltTag.assemble(ALT))
+        ) = eventTemplate(KIND, content, createdAt) {
-            return signer.sign(createdAt, KIND, tags, "")
+            dTag(dTag)
+            title(title)
+            alt(ALT)
+            initializer()
         }
     }
 }

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip52Calendar/CalendarRSVPEvent.kt

@@ -23,10 +23,21 @@ package com.vitorpamplona.quartz.nip52Calendar
 import androidx.compose.runtime.Immutable
 import com.vitorpamplona.quartz.nip01Core.core.BaseAddressableEvent
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
-import com.vitorpamplona.quartz.nip01Core.core.firstTagValue
+import com.vitorpamplona.quartz.nip01Core.core.TagArrayBuilder
-import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
+import com.vitorpamplona.quartz.nip01Core.signers.eventTemplate
-import com.vitorpamplona.quartz.nip31Alts.AltTag
+import com.vitorpamplona.quartz.nip01Core.tags.aTag.ATag
+import com.vitorpamplona.quartz.nip01Core.tags.aTag.aTag
+import com.vitorpamplona.quartz.nip01Core.tags.aTag.firstTaggedAddress
+import com.vitorpamplona.quartz.nip01Core.tags.dTag.dTag
+import com.vitorpamplona.quartz.nip01Core.tags.events.ETag
+import com.vitorpamplona.quartz.nip01Core.tags.events.firstTaggedEvent
+import com.vitorpamplona.quartz.nip01Core.tags.people.PTag
+import com.vitorpamplona.quartz.nip31Alts.alt
+import com.vitorpamplona.quartz.nip52Calendar.tags.FreeBusyTag
+import com.vitorpamplona.quartz.nip52Calendar.tags.RSVPStatusTag
 import com.vitorpamplona.quartz.utils.TimeUtils
+import kotlin.uuid.ExperimentalUuidApi
+import kotlin.uuid.Uuid
 
 @Immutable
 class CalendarRSVPEvent(
@@ -37,27 +48,42 @@ class CalendarRSVPEvent(
     content: String,
     sig: HexKey,
 ) : BaseAddressableEvent(id, pubKey, createdAt, KIND, tags, content, sig) {
-    fun location() = tags.firstTagValue("location")
+    fun status() = tags.firstNotNullOfOrNull(RSVPStatusTag::parse)
 
-    fun start() = tags.firstTagValue("start")
+    fun statusValue() = tags.firstNotNullOfOrNull(RSVPStatusTag::parseValue)
 
-    fun end() = tags.firstTagValue("end")
+    fun freebusy() = tags.firstNotNullOfOrNull(FreeBusyTag::parse)
 
-    //    ["L", "status"],
+    fun calendarEventAddress() = firstTaggedAddress()
-    //    ["l", "<accepted/declined/tentative>", "status"],
+
-    //    ["L", "freebusy"],
+    fun calendarEventId() = firstTaggedEvent()
-    //    ["l", "<free/busy>", "freebusy"]
+
+    fun calendarEventAuthor() = tags.firstNotNullOfOrNull(PTag::parse)
 
     companion object {
         const val KIND = 31925
         const val ALT = "Calendar event's invitation response"
 
-        suspend fun create(
+        @OptIn(ExperimentalUuidApi::class)
-            signer: NostrSigner,
+        fun build(
+            calendarEventAddress: ATag,
+            status: RSVPStatusTag.STATUS,
+            content: String = "",
+            calendarEventId: ETag? = null,
+            calendarEventAuthor: PTag? = null,
+            freebusy: FreeBusyTag.STATUS? = null,
+            dTag: String = Uuid.random().toString(),
             createdAt: Long = TimeUtils.now(),
-        ): CalendarRSVPEvent {
+            initializer: TagArrayBuilder<CalendarRSVPEvent>.() -> Unit = {},
-            val tags = arrayOf(AltTag.assemble(ALT))
+        ) = eventTemplate(KIND, content, createdAt) {
-            return signer.sign(createdAt, KIND, tags, "")
+            dTag(dTag)
+            aTag(calendarEventAddress)
+            status(status)
+            calendarEventId?.let { add(it.toTagArray()) }
+            calendarEventAuthor?.let { add(it.toTagArray()) }
+            freebusy?.let { freebusy(it) }
+            alt(ALT)
+            initializer()
         }
     }
 }

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip52Calendar/CalendarTimeSlotEvent.kt

@@ -23,11 +23,23 @@ package com.vitorpamplona.quartz.nip52Calendar
 import androidx.compose.runtime.Immutable
 import com.vitorpamplona.quartz.nip01Core.core.BaseAddressableEvent
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.core.TagArrayBuilder
 import com.vitorpamplona.quartz.nip01Core.core.firstTagValue
 import com.vitorpamplona.quartz.nip01Core.core.firstTagValueAsLong
-import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
+import com.vitorpamplona.quartz.nip01Core.signers.eventTemplate
-import com.vitorpamplona.quartz.nip31Alts.AltTag
+import com.vitorpamplona.quartz.nip01Core.tags.dTag.dTag
+import com.vitorpamplona.quartz.nip01Core.tags.geohash.GeoHashTag
+import com.vitorpamplona.quartz.nip01Core.tags.hashtags.hashtags
+import com.vitorpamplona.quartz.nip01Core.tags.people.PTag
+import com.vitorpamplona.quartz.nip01Core.tags.references.references
+import com.vitorpamplona.quartz.nip23LongContent.tags.ImageTag
+import com.vitorpamplona.quartz.nip23LongContent.tags.SummaryTag
+import com.vitorpamplona.quartz.nip23LongContent.tags.TitleTag
+import com.vitorpamplona.quartz.nip31Alts.alt
+import com.vitorpamplona.quartz.nip52Calendar.tags.LocationTag
 import com.vitorpamplona.quartz.utils.TimeUtils
+import kotlin.uuid.ExperimentalUuidApi
+import kotlin.uuid.Uuid
 
 @Immutable
 class CalendarTimeSlotEvent(
@@ -38,31 +50,56 @@ class CalendarTimeSlotEvent(
     content: String,
     sig: HexKey,
 ) : BaseAddressableEvent(id, pubKey, createdAt, KIND, tags, content, sig) {
-    fun location() = tags.firstTagValue("location")
+    fun title() = tags.firstNotNullOfOrNull(TitleTag::parse)
+
+    fun location() = tags.firstNotNullOfOrNull(LocationTag::parse)
+
+    fun locations() = tags.mapNotNull(LocationTag::parse)
 
     fun start() = tags.firstTagValueAsLong("start")
 
     fun end() = tags.firstTagValueAsLong("end")
 
-    fun startTmz() = tags.firstTagValueAsLong("start_tzid")
+    fun startTzId() = tags.firstTagValue("start_tzid")
 
-    fun endTmz() = tags.firstTagValueAsLong("end_tzid")
+    fun endTzId() = tags.firstTagValue("end_tzid")
 
-    //    ["start", "<Unix timestamp in seconds>"],
+    fun summary() = tags.firstNotNullOfOrNull(SummaryTag::parse)
-    //    ["end", "<Unix timestamp in seconds>"],
+
-    //    ["start_tzid", "<IANA Time Zone Database identifier>"],
+    fun image() = tags.firstNotNullOfOrNull(ImageTag::parse)
-    //    ["end_tzid", "<IANA Time Zone Database identifier>"],
+
+    fun geohash() = tags.firstNotNullOfOrNull(GeoHashTag::parse)
+
+    fun hashtags() = tags.hashtags()
+
+    fun participants() = tags.mapNotNull(PTag::parse)
+
+    fun references() = tags.references()
 
     companion object {
         const val KIND = 31923
         const val ALT = "Calendar time-slot event"
 
-        suspend fun create(
+        @OptIn(ExperimentalUuidApi::class)
-            signer: NostrSigner,
+        fun build(
+            title: String,
+            start: Long,
+            content: String = "",
+            end: Long? = null,
+            startTzId: String? = null,
+            endTzId: String? = null,
+            dTag: String = Uuid.random().toString(),
             createdAt: Long = TimeUtils.now(),
-        ): CalendarTimeSlotEvent {
+            initializer: TagArrayBuilder<CalendarTimeSlotEvent>.() -> Unit = {},
-            val tags = arrayOf(AltTag.assemble(ALT))
+        ) = eventTemplate(KIND, content, createdAt) {
-            return signer.sign(createdAt, KIND, tags, "")
+            dTag(dTag)
+            title(title)
+            startTimestamp(start)
+            end?.let { endTimestamp(it) }
+            startTzId?.let { startTzId(it) }
+            endTzId?.let { endTzId(it) }
+            alt(ALT)
+            initializer()
         }
     }
 }

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip52Calendar/TagArrayBuilderExt.kt

@@ -0,0 +1,89 @@
+/*
+ * 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.nip52Calendar
+
+import com.vitorpamplona.quartz.nip01Core.core.TagArrayBuilder
+import com.vitorpamplona.quartz.nip01Core.tags.geohash.GeoHashTag
+import com.vitorpamplona.quartz.nip01Core.tags.people.PTag
+import com.vitorpamplona.quartz.nip23LongContent.tags.ImageTag
+import com.vitorpamplona.quartz.nip23LongContent.tags.SummaryTag
+import com.vitorpamplona.quartz.nip23LongContent.tags.TitleTag
+import com.vitorpamplona.quartz.nip52Calendar.tags.FreeBusyTag
+import com.vitorpamplona.quartz.nip52Calendar.tags.LocationTag
+import com.vitorpamplona.quartz.nip52Calendar.tags.RSVPStatusTag
+
+// CalendarDateSlotEvent builder extensions
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.title(title: String) = addUnique(TitleTag.assemble(title))
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.startDate(date: String) = addUnique(arrayOf("start", date))
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.endDate(date: String) = addUnique(arrayOf("end", date))
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.location(location: String) = add(LocationTag.assemble(location))
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.locations(locations: List<String>) = addAll(locations.map { LocationTag.assemble(it) })
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.summary(summary: String) = addUnique(SummaryTag.assemble(summary))
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.image(imageUrl: String) = addUnique(ImageTag.assemble(imageUrl))
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.geohash(geohash: String) = addAll(GeoHashTag.assemble(geohash).toList())
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.participant(p: PTag) = add(p.toTagArray())
+
+fun TagArrayBuilder<CalendarDateSlotEvent>.participants(ps: List<PTag>) = addAll(ps.map { it.toTagArray() })
+
+// CalendarTimeSlotEvent builder extensions
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.title(title: String) = addUnique(TitleTag.assemble(title))
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.startTimestamp(timestamp: Long) = addUnique(arrayOf("start", timestamp.toString()))
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.endTimestamp(timestamp: Long) = addUnique(arrayOf("end", timestamp.toString()))
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.startTzId(tzId: String) = addUnique(arrayOf("start_tzid", tzId))
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.endTzId(tzId: String) = addUnique(arrayOf("end_tzid", tzId))
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.location(location: String) = add(LocationTag.assemble(location))
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.locations(locations: List<String>) = addAll(locations.map { LocationTag.assemble(it) })
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.summary(summary: String) = addUnique(SummaryTag.assemble(summary))
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.image(imageUrl: String) = addUnique(ImageTag.assemble(imageUrl))
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.geohash(geohash: String) = addAll(GeoHashTag.assemble(geohash).toList())
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.participant(p: PTag) = add(p.toTagArray())
+
+fun TagArrayBuilder<CalendarTimeSlotEvent>.participants(ps: List<PTag>) = addAll(ps.map { it.toTagArray() })
+
+// CalendarEvent builder extensions
+
+fun TagArrayBuilder<CalendarEvent>.title(title: String) = addUnique(TitleTag.assemble(title))
+
+// CalendarRSVPEvent builder extensions
+
+fun TagArrayBuilder<CalendarRSVPEvent>.status(status: RSVPStatusTag.STATUS) = addUnique(status.toTagArray())
+
+fun TagArrayBuilder<CalendarRSVPEvent>.freebusy(fb: FreeBusyTag.STATUS) = addUnique(fb.toTagArray())

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip52Calendar/tags/FreeBusyTag.kt

@@ -0,0 +1,47 @@
+/*
+ * 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.nip52Calendar.tags
+
+import com.vitorpamplona.quartz.nip01Core.core.has
+import com.vitorpamplona.quartz.utils.ensure
+
+class FreeBusyTag {
+    companion object {
+        const val TAG_NAME = "fb"
+
+        fun parse(tag: Array<String>): STATUS? {
+            ensure(tag.has(1)) { return null }
+            ensure(tag[0] == TAG_NAME) { return null }
+            ensure(tag[1].isNotEmpty()) { return null }
+            return STATUS.entries.firstOrNull { it.value == tag[1] }
+        }
+    }
+
+    enum class STATUS(
+        val value: String,
+    ) {
+        FREE("free"),
+        BUSY("busy"),
+        ;
+
+        fun toTagArray() = arrayOf(TAG_NAME, value)
+    }
+}

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip52Calendar/tags/LocationTag.kt

@@ -0,0 +1,39 @@
+/*
+ * 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.nip52Calendar.tags
+
+import com.vitorpamplona.quartz.nip01Core.core.has
+import com.vitorpamplona.quartz.utils.ensure
+
+class LocationTag {
+    companion object {
+        const val TAG_NAME = "location"
+
+        fun parse(tag: Array<String>): String? {
+            ensure(tag.has(1)) { return null }
+            ensure(tag[0] == TAG_NAME) { return null }
+            ensure(tag[1].isNotEmpty()) { return null }
+            return tag[1]
+        }
+
+        fun assemble(locationName: String) = arrayOf(TAG_NAME, locationName)
+    }
+}

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip52Calendar/tags/RSVPStatusTag.kt

@@ -0,0 +1,55 @@
+/*
+ * 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.nip52Calendar.tags
+
+import com.vitorpamplona.quartz.nip01Core.core.has
+import com.vitorpamplona.quartz.utils.ensure
+
+class RSVPStatusTag {
+    companion object {
+        const val TAG_NAME = "status"
+
+        fun parse(tag: Array<String>): STATUS? {
+            ensure(tag.has(1)) { return null }
+            ensure(tag[0] == TAG_NAME) { return null }
+            ensure(tag[1].isNotEmpty()) { return null }
+            return STATUS.entries.firstOrNull { it.value == tag[1] }
+        }
+
+        fun parseValue(tag: Array<String>): String? {
+            ensure(tag.has(1)) { return null }
+            ensure(tag[0] == TAG_NAME) { return null }
+            ensure(tag[1].isNotEmpty()) { return null }
+            return tag[1]
+        }
+    }
+
+    enum class STATUS(
+        val value: String,
+    ) {
+        ACCEPTED("accepted"),
+        DECLINED("declined"),
+        TENTATIVE("tentative"),
+        ;
+
+        fun toTagArray() = arrayOf(TAG_NAME, value)
+    }
+}