From db1b785b868778d6dca94e6115aee08ac043d4de Mon Sep 17 00:00:00 2001
From: Brett Hoerner <brett@bretthoerner.com>
Date: Thu, 25 Apr 2024 09:22:00 -0600
Subject: [PATCH] chore(plugin-server): set 'force_upgrade' for 'person_mode'
 when applicable

---
 plugin-server/src/types.ts                          | 10 ++++++++--
 plugin-server/src/worker/ingestion/person-state.ts  |  9 +++++++--
 plugin-server/src/worker/ingestion/process-event.ts | 10 +++++++++-
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/plugin-server/src/types.ts b/plugin-server/src/types.ts
index 331fc52f2e696f..f3106fe62dd24c 100644
--- a/plugin-server/src/types.ts
+++ b/plugin-server/src/types.ts
@@ -619,6 +619,7 @@ interface BaseEvent {
 export type ISOTimestamp = Brand<string, 'ISOTimestamp'>
 export type ClickHouseTimestamp = Brand<string, 'ClickHouseTimestamp'>
 export type ClickHouseTimestampSecondPrecision = Brand<string, 'ClickHouseTimestamp'>
+export type PersonMode = 'full' | 'propertyless' | 'force_upgrade'
 
 /** Raw event row from ClickHouse. */
 export interface RawClickHouseEvent extends BaseEvent {
@@ -638,7 +639,7 @@ export interface RawClickHouseEvent extends BaseEvent {
     group2_created_at?: ClickHouseTimestamp
     group3_created_at?: ClickHouseTimestamp
     group4_created_at?: ClickHouseTimestamp
-    person_mode: 'full' | 'propertyless'
+    person_mode: PersonMode
 }
 
 /** Parsed event row from ClickHouse. */
@@ -659,7 +660,7 @@ export interface ClickHouseEvent extends BaseEvent {
     group2_created_at?: DateTime | null
     group3_created_at?: DateTime | null
     group4_created_at?: DateTime | null
-    person_mode: 'full' | 'propertyless'
+    person_mode: PersonMode
 }
 
 /** Event in a database-agnostic shape, AKA an ingestion event.
@@ -746,6 +747,11 @@ export interface Person {
     properties: Properties
     uuid: string
     created_at: DateTime
+
+    // Set to `true` when an existing person row was found for this `distinct_id`, but the event was
+    // sent with `$process_person_profile=false`. This is an unexpected branch that we want to flag
+    // for debugging and billing purposes, and typically means a misconfigured SDK.
+    force_upgrade?: boolean
 }
 
 /** Clickhouse Person model. */
diff --git a/plugin-server/src/worker/ingestion/person-state.ts b/plugin-server/src/worker/ingestion/person-state.ts
index e7f3652b2ef250..ca250aa3d52da9 100644
--- a/plugin-server/src/worker/ingestion/person-state.ts
+++ b/plugin-server/src/worker/ingestion/person-state.ts
@@ -114,11 +114,16 @@ export class PersonState {
     async update(): Promise<Person> {
         if (!this.processPerson) {
             if (this.lazyPersonCreation) {
-                const person = await this.db.fetchPerson(this.teamId, this.distinctId, { useReadReplica: true })
-                if (person) {
+                const existingPerson = await this.db.fetchPerson(this.teamId, this.distinctId, { useReadReplica: true })
+                if (existingPerson) {
+                    const person = existingPerson as Person
+
                     // Ensure person properties don't propagate elsewhere, such as onto the event itself.
                     person.properties = {}
 
+                    // See documentation on the field.
+                    person.force_upgrade = true
+
                     return person
                 }
 
diff --git a/plugin-server/src/worker/ingestion/process-event.ts b/plugin-server/src/worker/ingestion/process-event.ts
index 8b57e261900466..d3f49b85cfd717 100644
--- a/plugin-server/src/worker/ingestion/process-event.ts
+++ b/plugin-server/src/worker/ingestion/process-event.ts
@@ -11,6 +11,7 @@ import {
     Hub,
     ISOTimestamp,
     Person,
+    PersonMode,
     PreIngestionEvent,
     RawClickHouseEvent,
     Team,
@@ -239,6 +240,13 @@ export class EventsProcessor {
 
         // TODO: Remove Redis caching for person that's not used anymore
 
+        let personMode: PersonMode = 'full'
+        if (person.force_upgrade) {
+            personMode = 'force_upgrade'
+        } else if (!processPerson) {
+            personMode = 'propertyless'
+        }
+
         const rawEvent: RawClickHouseEvent = {
             uuid,
             event: safeClickhouseString(event),
@@ -251,7 +259,7 @@ export class EventsProcessor {
             person_id: person.uuid,
             person_properties: eventPersonProperties,
             person_created_at: castTimestampOrNow(person.created_at, TimestampFormat.ClickHouseSecondPrecision),
-            person_mode: processPerson ? 'full' : 'propertyless',
+            person_mode: personMode,
             ...groupsColumns,
         }