From 8869199c3e9b647fbf3bd509ae83e5740bce3211 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Go=CC=88rdes?= <d.goerdes@overlap.at>
Date: Mon, 9 Feb 2026 21:03:17 +0100
Subject: [PATCH 1/3] feat(core): enhance command, event, and query input types
 for better type safety and validation

---
 packages/core/src/lib/message/command.ts | 53 +++++++++++-------------
 packages/core/src/lib/message/event.ts   | 51 ++++++++++-------------
 packages/core/src/lib/message/query.ts   | 47 ++++++++++-----------
 3 files changed, 68 insertions(+), 83 deletions(-)

diff --git a/packages/core/src/lib/message/command.ts b/packages/core/src/lib/message/command.ts
index e008abd..896ae3f 100644
--- a/packages/core/src/lib/message/command.ts
+++ b/packages/core/src/lib/message/command.ts
@@ -110,42 +110,39 @@ export const commandSchema: CommandSchemaType = z.object({
 
 /**
  * Input for creating a command.
+ *
+ * When a specific command type is provided via the generic parameter,
+ * the input is validated against that type. This means fields like
+ * `type` and `data` must match the narrower types of `TCommand`.
  */
-export type CreateCommandInput = Partial<Omit<Command, 'specversion'>> & {
-    type: string;
-    source: string;
-    data: unknown;
-};
+export type CreateCommandInput<TCommand extends Command = Command> =
+    & Partial<
+        Pick<
+            TCommand,
+            'id' | 'correlationid' | 'time' | 'subject' | 'datacontenttype' | 'dataschema'
+        >
+    >
+    & Pick<TCommand, 'type' | 'source' | 'data'>;
 
 /**
  * Creates a command based on input data with the convenience
  * to skip properties and use the defaults for the rest.
  */
 export const createCommand = <TCommand extends Command>(
-    {
-        id,
-        correlationid,
-        time,
-        source,
-        type,
-        subject,
-        data,
-        datacontenttype,
-        dataschema,
-    }: CreateCommandInput,
+    input: CreateCommandInput<TCommand>,
 ): TCommand => {
     const command = {
-        specversion: '1.0',
-        id: id ?? ulid(),
-        correlationid: correlationid ?? ulid(),
-        time: time ?? new Date().toISOString(),
-        source,
-        type,
-        ...(subject && { subject }),
-        data,
-        datacontenttype: datacontenttype ?? 'application/json',
-        ...(dataschema && { dataschema }),
-    } as TCommand;
+        specversion: '1.0' as const,
+        id: input.id ?? ulid(),
+        correlationid: input.correlationid ?? ulid(),
+        time: input.time ?? new Date().toISOString(),
+        source: input.source,
+        type: input.type,
+        ...(input.subject && { subject: input.subject }),
+        data: input.data,
+        datacontenttype: input.datacontenttype ?? 'application/json',
+        ...(input.dataschema && { dataschema: input.dataschema }),
+    };
 
-    return command;
+    return command as TCommand;
 };
diff --git a/packages/core/src/lib/message/event.ts b/packages/core/src/lib/message/event.ts
index ce8464e..856e857 100644
--- a/packages/core/src/lib/message/event.ts
+++ b/packages/core/src/lib/message/event.ts
@@ -113,43 +113,36 @@ export const eventSchema: EventSchemaType = z.object({
 
 /**
  * Input for creating an event.
+ *
+ * When a specific event type is provided via the generic parameter,
+ * the input is validated against that type. This means fields like
+ * `type` and `data` must match the narrower types of `TEvent`.
  */
-export type CreateEventInput = Partial<Omit<Event, 'specversion'>> & {
-    type: string;
-    source: string;
-    subject: string;
-    data: unknown;
-};
+export type CreateEventInput<TEvent extends Event = Event> =
+    & Partial<
+        Pick<TEvent, 'id' | 'correlationid' | 'time' | 'datacontenttype' | 'dataschema'>
+    >
+    & Pick<TEvent, 'type' | 'source' | 'subject' | 'data'>;
 
 /**
  * Creates an event based on input data with the convenience
  * to skip properties and use the defaults for the rest.
  */
 export const createEvent = <TEvent extends Event>(
-    {
-        id,
-        correlationid,
-        time,
-        source,
-        type,
-        subject,
-        data,
-        datacontenttype,
-        dataschema,
-    }: CreateEventInput,
+    input: CreateEventInput<TEvent>,
 ): TEvent => {
     const event = {
-        specversion: '1.0',
-        id: id ?? ulid(),
-        correlationid: correlationid ?? ulid(),
-        time: time ?? new Date().toISOString(),
-        source,
-        type,
-        subject,
-        data,
-        datacontenttype: datacontenttype ?? 'application/json',
-        ...(dataschema && { dataschema }),
-    } as TEvent;
+        specversion: '1.0' as const,
+        id: input.id ?? ulid(),
+        correlationid: input.correlationid ?? ulid(),
+        time: input.time ?? new Date().toISOString(),
+        source: input.source,
+        type: input.type,
+        subject: input.subject,
+        data: input.data,
+        datacontenttype: input.datacontenttype ?? 'application/json',
+        ...(input.dataschema && { dataschema: input.dataschema }),
+    };
 
-    return event;
+    return event as TEvent;
 };
diff --git a/packages/core/src/lib/message/query.ts b/packages/core/src/lib/message/query.ts
index c5ac52d..7895fb8 100644
--- a/packages/core/src/lib/message/query.ts
+++ b/packages/core/src/lib/message/query.ts
@@ -104,40 +104,35 @@ export const querySchema: QuerySchemaType = z.object({
 
 /**
  * Input for creating a query.
+ *
+ * When a specific query type is provided via the generic parameter,
+ * the input is validated against that type. This means fields like
+ * `type` and `data` must match the narrower types of `TQuery`.
  */
-export type CreateQueryInput = Partial<Omit<Query, 'specversion'>> & {
-    type: string;
-    source: string;
-    data: unknown;
-};
+export type CreateQueryInput<TQuery extends Query = Query> =
+    & Partial<
+        Pick<TQuery, 'id' | 'correlationid' | 'time' | 'datacontenttype' | 'dataschema'>
+    >
+    & Pick<TQuery, 'type' | 'source' | 'data'>;
 
 /**
  * Creates a query based on input data with the convenience
  * to skip properties and use the defaults for the rest.
  */
 export const createQuery = <TQuery extends Query>(
-    {
-        id,
-        correlationid,
-        time,
-        source,
-        type,
-        data,
-        datacontenttype,
-        dataschema,
-    }: CreateQueryInput,
+    input: CreateQueryInput<TQuery>,
 ): TQuery => {
     const query = {
-        specversion: '1.0',
-        id: id ?? ulid(),
-        correlationid: correlationid ?? ulid(),
-        time: time ?? new Date().toISOString(),
-        source,
-        type,
-        data,
-        datacontenttype: datacontenttype ?? 'application/json',
-        ...(dataschema && { dataschema }),
-    } as TQuery;
+        specversion: '1.0' as const,
+        id: input.id ?? ulid(),
+        correlationid: input.correlationid ?? ulid(),
+        time: input.time ?? new Date().toISOString(),
+        source: input.source,
+        type: input.type,
+        data: input.data,
+        datacontenttype: input.datacontenttype ?? 'application/json',
+        ...(input.dataschema && { dataschema: input.dataschema }),
+    };
 
-    return query;
+    return query as TQuery;
 };

From 46ba1c5b6f19e7042105cfa73e2b54c000262020 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Go=CC=88rdes?= <d.goerdes@overlap.at>
Date: Mon, 9 Feb 2026 21:04:34 +0100
Subject: [PATCH 2/3] fix(core): correct typo in event schema documentation

---
 packages/core/src/lib/message/event.ts | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/packages/core/src/lib/message/event.ts b/packages/core/src/lib/message/event.ts
index 856e857..6f97c89 100644
--- a/packages/core/src/lib/message/event.ts
+++ b/packages/core/src/lib/message/event.ts
@@ -87,7 +87,7 @@ export type EventSchemaType = z.ZodObject<{
 /**
  * The Zod schema matching the Event type.
  *
- * Zod is the default for validating incomming messages.
+ * Zod is the default for validating incoming messages.
  *
  * We do not infer the Event type from this schema because of
  * slow type issues see https://jsr.io/docs/about-slow-types for more details.
@@ -120,7 +120,10 @@ export const eventSchema: EventSchemaType = z.object({
  */
 export type CreateEventInput<TEvent extends Event = Event> =
     & Partial<
-        Pick<TEvent, 'id' | 'correlationid' | 'time' | 'datacontenttype' | 'dataschema'>
+        Pick<
+            TEvent,
+            'id' | 'correlationid' | 'time' | 'datacontenttype' | 'dataschema'
+        >
     >
     & Pick<TEvent, 'type' | 'source' | 'subject' | 'data'>;
 

From d94706831b97bcac97fb67251b2715f8d56e233e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Go=CC=88rdes?= <d.goerdes@overlap.at>
Date: Mon, 9 Feb 2026 21:10:40 +0100
Subject: [PATCH 3/3] fixes formatting

---
 packages/core/src/lib/message/command.ts | 7 ++++++-
 packages/core/src/lib/message/query.ts   | 5 ++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/packages/core/src/lib/message/command.ts b/packages/core/src/lib/message/command.ts
index 896ae3f..3f2015f 100644
--- a/packages/core/src/lib/message/command.ts
+++ b/packages/core/src/lib/message/command.ts
@@ -119,7 +119,12 @@ export type CreateCommandInput<TCommand extends Command = Command> =
     & Partial<
         Pick<
             TCommand,
-            'id' | 'correlationid' | 'time' | 'subject' | 'datacontenttype' | 'dataschema'
+            | 'id'
+            | 'correlationid'
+            | 'time'
+            | 'subject'
+            | 'datacontenttype'
+            | 'dataschema'
         >
     >
     & Pick<TCommand, 'type' | 'source' | 'data'>;
diff --git a/packages/core/src/lib/message/query.ts b/packages/core/src/lib/message/query.ts
index 7895fb8..8b45431 100644
--- a/packages/core/src/lib/message/query.ts
+++ b/packages/core/src/lib/message/query.ts
@@ -111,7 +111,10 @@ export const querySchema: QuerySchemaType = z.object({
  */
 export type CreateQueryInput<TQuery extends Query = Query> =
     & Partial<
-        Pick<TQuery, 'id' | 'correlationid' | 'time' | 'datacontenttype' | 'dataschema'>
+        Pick<
+            TQuery,
+            'id' | 'correlationid' | 'time' | 'datacontenttype' | 'dataschema'
+        >
     >
     & Pick<TQuery, 'type' | 'source' | 'data'>;