From 42e3e059f2450bd8ba113437c95a019fafe6814f Mon Sep 17 00:00:00 2001
From: Fred Tzeng <fred.tzeng@temporal.io>
Date: Fri, 3 Apr 2026 12:50:43 -0700
Subject: [PATCH 1/8] Add start delay, callbacks, and links to
 StartActivityExecutionRequest

Added links/callbacks to describe and start responses

Update openapi
---
 openapi/openapiv2.json                        | 58 +++++++++++++++++++
 openapi/openapiv3.yaml                        | 42 ++++++++++++++
 temporal/api/activity/v1/message.proto        |  3 +
 temporal/api/common/v1/message.proto          |  8 +++
 .../workflowservice/v1/request_response.proto | 12 ++++
 5 files changed, 123 insertions(+)

diff --git a/openapi/openapiv2.json b/openapi/openapiv2.json
index bf8692b66..0e4683266 100644
--- a/openapi/openapiv2.json
+++ b/openapi/openapiv2.json
@@ -9156,6 +9156,21 @@
       },
       "description": "Target a worker polling on a Nexus task queue in a specific namespace."
     },
+    "LinkActivity": {
+      "type": "object",
+      "properties": {
+        "namespace": {
+          "type": "string"
+        },
+        "activityId": {
+          "type": "string"
+        },
+        "runId": {
+          "type": "string"
+        }
+      },
+      "description": "A link to an activity."
+    },
     "LinkBatchJob": {
       "type": "object",
       "properties": {
@@ -10437,6 +10452,26 @@
         "priority": {
           "$ref": "#/definitions/v1Priority",
           "description": "Priority metadata."
+        },
+        "startDelay": {
+          "type": "string",
+          "description": "Time to wait before dispatching the first activity."
+        },
+        "completionCallbacks": {
+          "type": "array",
+          "items": {
+            "type": "object",
+            "$ref": "#/definitions/v1Callback"
+          },
+          "description": "Callbacks to be called by the server when this activity reaches a terminal state.\nCallback addresses must be whitelisted in the server's dynamic configuration."
+        },
+        "links": {
+          "type": "array",
+          "items": {
+            "type": "object",
+            "$ref": "#/definitions/apiCommonV1Link"
+          },
+          "description": "Links to be associated with the activity."
         }
       }
     },
@@ -11249,6 +11284,14 @@
         "canceledReason": {
           "type": "string",
           "description": "Set if activity cancelation was requested."
+        },
+        "links": {
+          "type": "array",
+          "items": {
+            "type": "object",
+            "$ref": "#/definitions/v1Link"
+          },
+          "description": "Links to be associated with the activity."
         }
       },
       "description": "Information about a standalone activity."
@@ -12865,6 +12908,14 @@
           "type": "string",
           "format": "byte",
           "description": "Token for follow-on long-poll requests. Absent only if the activity is complete."
+        },
+        "callbacks": {
+          "type": "array",
+          "items": {
+            "type": "object",
+            "$ref": "#/definitions/v1CallbackInfo"
+          },
+          "description": "Callbacks attached to this activity execution and their current state."
         }
       }
     },
@@ -13952,6 +14003,9 @@
         },
         "batchJob": {
           "$ref": "#/definitions/LinkBatchJob"
+        },
+        "activity": {
+          "$ref": "#/definitions/LinkActivity"
         }
       },
       "description": "Link can be associated with history events. It might contain information about an external entity\nrelated to the history event. For example, workflow A makes a Nexus call that starts workflow B:\nin this case, a history event in workflow A could contain a Link to the workflow started event in\nworkflow B, and vice-versa."
@@ -16442,6 +16496,10 @@
         "started": {
           "type": "boolean",
           "description": "If true, a new activity was started."
+        },
+        "link": {
+          "$ref": "#/definitions/v1Link",
+          "description": "Link to the activity event."
         }
       }
     },
diff --git a/openapi/openapiv3.yaml b/openapi/openapiv3.yaml
index c4ee8a0b6..9df1c8046 100644
--- a/openapi/openapiv3.yaml
+++ b/openapi/openapiv3.yaml
@@ -8236,6 +8236,11 @@ components:
         canceledReason:
           type: string
           description: Set if activity cancelation was requested.
+        links:
+          type: array
+          items:
+            $ref: '#/components/schemas/Link'
+          description: Links to be associated with the activity.
       description: Information about a standalone activity.
     ActivityExecutionListInfo:
       type: object
@@ -9912,6 +9917,11 @@ components:
           type: string
           description: Token for follow-on long-poll requests. Absent only if the activity is complete.
           format: bytes
+        callbacks:
+          type: array
+          items:
+            $ref: '#/components/schemas/CallbackInfo'
+          description: Callbacks attached to this activity execution and their current state.
     DescribeBatchOperationResponse:
       type: object
       properties:
@@ -10934,11 +10944,23 @@ components:
           $ref: '#/components/schemas/Link_WorkflowEvent'
         batchJob:
           $ref: '#/components/schemas/Link_BatchJob'
+        activity:
+          $ref: '#/components/schemas/Link_Activity'
       description: |-
         Link can be associated with history events. It might contain information about an external entity
          related to the history event. For example, workflow A makes a Nexus call that starts workflow B:
          in this case, a history event in workflow A could contain a Link to the workflow started event in
          workflow B, and vice-versa.
+    Link_Activity:
+      type: object
+      properties:
+        namespace:
+          type: string
+        activityId:
+          type: string
+        runId:
+          type: string
+      description: A link to an activity.
     Link_BatchJob:
       type: object
       properties:
@@ -14299,6 +14321,22 @@ components:
           allOf:
             - $ref: '#/components/schemas/Priority'
           description: Priority metadata.
+        startDelay:
+          pattern: ^-?(?:0|[1-9][0-9]{0,11})(?:\.[0-9]{1,9})?s$
+          type: string
+          description: Time to wait before dispatching the first activity.
+        completionCallbacks:
+          type: array
+          items:
+            $ref: '#/components/schemas/Callback'
+          description: |-
+            Callbacks to be called by the server when this activity reaches a terminal state.
+             Callback addresses must be whitelisted in the server's dynamic configuration.
+        links:
+          type: array
+          items:
+            $ref: '#/components/schemas/Link'
+          description: Links to be associated with the activity.
     StartActivityExecutionResponse:
       type: object
       properties:
@@ -14308,6 +14346,10 @@ components:
         started:
           type: boolean
           description: If true, a new activity was started.
+        link:
+          allOf:
+            - $ref: '#/components/schemas/Link'
+          description: Link to the activity event.
     StartBatchOperationRequest:
       type: object
       properties:
diff --git a/temporal/api/activity/v1/message.proto b/temporal/api/activity/v1/message.proto
index 37eeae33c..1719eeb5d 100644
--- a/temporal/api/activity/v1/message.proto
+++ b/temporal/api/activity/v1/message.proto
@@ -161,6 +161,9 @@ message ActivityExecutionInfo {
 
     // Set if activity cancelation was requested.
     string canceled_reason = 32;
+
+    // Links to be associated with the activity.
+    repeated temporal.api.common.v1.Link links = 33;
 }
 
 // Limited activity information returned in the list response.
diff --git a/temporal/api/common/v1/message.proto b/temporal/api/common/v1/message.proto
index 88c3a834e..419f08f68 100644
--- a/temporal/api/common/v1/message.proto
+++ b/temporal/api/common/v1/message.proto
@@ -240,9 +240,17 @@ message Link {
         string job_id = 1;
     }
 
+    // A link to an activity.
+    message Activity {
+        string namespace = 1;
+        string activity_id = 2;
+        string run_id = 3;
+    }
+
     oneof variant {
         WorkflowEvent workflow_event = 1;
         BatchJob batch_job = 2;
+        Activity activity = 3;
     }
 }
 
diff --git a/temporal/api/workflowservice/v1/request_response.proto b/temporal/api/workflowservice/v1/request_response.proto
index 0924c1aff..a86245016 100644
--- a/temporal/api/workflowservice/v1/request_response.proto
+++ b/temporal/api/workflowservice/v1/request_response.proto
@@ -2931,6 +2931,13 @@ message StartActivityExecutionRequest {
     temporal.api.sdk.v1.UserMetadata user_metadata = 17;
     // Priority metadata.
     temporal.api.common.v1.Priority priority = 18;
+    // Time to wait before dispatching the first activity.
+    google.protobuf.Duration start_delay = 19;
+    // Callbacks to be called by the server when this activity reaches a terminal state.
+    // Callback addresses must be whitelisted in the server's dynamic configuration.
+    repeated temporal.api.common.v1.Callback completion_callbacks = 20;
+    // Links to be associated with the activity.
+    repeated temporal.api.common.v1.Link links = 21;
 }
 
 message StartActivityExecutionResponse {
@@ -2938,6 +2945,8 @@ message StartActivityExecutionResponse {
     string run_id = 1;
     // If true, a new activity was started.
     bool started = 2;
+    // Link to the activity event.
+    temporal.api.common.v1.Link link = 4;
 }
 
 message DescribeActivityExecutionRequest {
@@ -2974,6 +2983,9 @@ message DescribeActivityExecutionResponse {
 
     // Token for follow-on long-poll requests. Absent only if the activity is complete.
     bytes long_poll_token = 5;
+
+    // Callbacks attached to this activity execution and their current state.
+    repeated temporal.api.workflow.v1.CallbackInfo callbacks = 6;
 }
 
 message PollActivityExecutionRequest {

From 507bf790c65951a26ef292fe5215bb9979fec6c2 Mon Sep 17 00:00:00 2001
From: Fred Tzeng <fred.tzeng@temporal.io>
Date: Tue, 7 Apr 2026 09:04:35 -0700
Subject: [PATCH 2/8] Fix proto numbering

---
 temporal/api/workflowservice/v1/request_response.proto | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/temporal/api/workflowservice/v1/request_response.proto b/temporal/api/workflowservice/v1/request_response.proto
index a86245016..3854b9ed8 100644
--- a/temporal/api/workflowservice/v1/request_response.proto
+++ b/temporal/api/workflowservice/v1/request_response.proto
@@ -2946,7 +2946,7 @@ message StartActivityExecutionResponse {
     // If true, a new activity was started.
     bool started = 2;
     // Link to the activity event.
-    temporal.api.common.v1.Link link = 4;
+    temporal.api.common.v1.Link link = 3;
 }
 
 message DescribeActivityExecutionRequest {

From 2f05ad952be37f1cc2d8aa06d5f63427724c3d7b Mon Sep 17 00:00:00 2001
From: Fred Tzeng <41805201+fretz12@users.noreply.github.com>
Date: Tue, 7 Apr 2026 09:59:02 -0700
Subject: [PATCH 3/8] Update
 temporal/api/workflowservice/v1/request_response.proto

Co-authored-by: Quinn Klassen <klassenq@gmail.com>
---
 temporal/api/workflowservice/v1/request_response.proto | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/temporal/api/workflowservice/v1/request_response.proto b/temporal/api/workflowservice/v1/request_response.proto
index 3854b9ed8..f3ecc7ff0 100644
--- a/temporal/api/workflowservice/v1/request_response.proto
+++ b/temporal/api/workflowservice/v1/request_response.proto
@@ -2945,7 +2945,7 @@ message StartActivityExecutionResponse {
     string run_id = 1;
     // If true, a new activity was started.
     bool started = 2;
-    // Link to the activity event.
+    // Link to the started activity.
     temporal.api.common.v1.Link link = 3;
 }
 

From de1c70f9094371c6a612b64cbd0429981bc0f3de Mon Sep 17 00:00:00 2001
From: Fred Tzeng <41805201+fretz12@users.noreply.github.com>
Date: Tue, 7 Apr 2026 09:59:18 -0700
Subject: [PATCH 4/8] Update temporal/api/activity/v1/message.proto

Co-authored-by: Spencer Judge <spencer@temporal.io>
---
 temporal/api/activity/v1/message.proto | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/temporal/api/activity/v1/message.proto b/temporal/api/activity/v1/message.proto
index 1719eeb5d..004ce6303 100644
--- a/temporal/api/activity/v1/message.proto
+++ b/temporal/api/activity/v1/message.proto
@@ -162,7 +162,7 @@ message ActivityExecutionInfo {
     // Set if activity cancelation was requested.
     string canceled_reason = 32;
 
-    // Links to be associated with the activity.
+    // Links associated with the activity.
     repeated temporal.api.common.v1.Link links = 33;
 }
 

From bb77190c35e06e47290cba9c5d9104d7d618e0f9 Mon Sep 17 00:00:00 2001
From: Fred Tzeng <fred.tzeng@temporal.io>
Date: Tue, 7 Apr 2026 10:00:18 -0700
Subject: [PATCH 5/8] Update openapi

---
 openapi/openapiv2.json | 4 ++--
 openapi/openapiv3.yaml | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/openapi/openapiv2.json b/openapi/openapiv2.json
index 0e4683266..f46d47c4f 100644
--- a/openapi/openapiv2.json
+++ b/openapi/openapiv2.json
@@ -11291,7 +11291,7 @@
             "type": "object",
             "$ref": "#/definitions/v1Link"
           },
-          "description": "Links to be associated with the activity."
+          "description": "Links associated with the activity."
         }
       },
       "description": "Information about a standalone activity."
@@ -16499,7 +16499,7 @@
         },
         "link": {
           "$ref": "#/definitions/v1Link",
-          "description": "Link to the activity event."
+          "description": "Link to the started activity."
         }
       }
     },
diff --git a/openapi/openapiv3.yaml b/openapi/openapiv3.yaml
index 9df1c8046..3380c36cb 100644
--- a/openapi/openapiv3.yaml
+++ b/openapi/openapiv3.yaml
@@ -8240,7 +8240,7 @@ components:
           type: array
           items:
             $ref: '#/components/schemas/Link'
-          description: Links to be associated with the activity.
+          description: Links associated with the activity.
       description: Information about a standalone activity.
     ActivityExecutionListInfo:
       type: object
@@ -14349,7 +14349,7 @@ components:
         link:
           allOf:
             - $ref: '#/components/schemas/Link'
-          description: Link to the activity event.
+          description: Link to the started activity.
     StartBatchOperationRequest:
       type: object
       properties:

From f0deaf5b5b96b5e5f8588a3a38bccf21e2a0a9dd Mon Sep 17 00:00:00 2001
From: Fred Tzeng <fred.tzeng@temporal.io>
Date: Tue, 7 Apr 2026 10:51:01 -0700
Subject: [PATCH 6/8] Address PR comments

---
 openapi/openapiv2.json                                 | 6 +-----
 openapi/openapiv3.yaml                                 | 8 +++-----
 temporal/api/workflowservice/v1/request_response.proto | 9 ++++-----
 3 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/openapi/openapiv2.json b/openapi/openapiv2.json
index f46d47c4f..72928a68a 100644
--- a/openapi/openapiv2.json
+++ b/openapi/openapiv2.json
@@ -10453,10 +10453,6 @@
           "$ref": "#/definitions/v1Priority",
           "description": "Priority metadata."
         },
-        "startDelay": {
-          "type": "string",
-          "description": "Time to wait before dispatching the first activity."
-        },
         "completionCallbacks": {
           "type": "array",
           "items": {
@@ -10471,7 +10467,7 @@
             "type": "object",
             "$ref": "#/definitions/apiCommonV1Link"
           },
-          "description": "Links to be associated with the activity."
+          "description": "Links to be associated with the activity. Callbacks may also have associated links;\nlinks already included with a callback should not be duplicated here."
         }
       }
     },
diff --git a/openapi/openapiv3.yaml b/openapi/openapiv3.yaml
index 3380c36cb..25ab730d7 100644
--- a/openapi/openapiv3.yaml
+++ b/openapi/openapiv3.yaml
@@ -14321,10 +14321,6 @@ components:
           allOf:
             - $ref: '#/components/schemas/Priority'
           description: Priority metadata.
-        startDelay:
-          pattern: ^-?(?:0|[1-9][0-9]{0,11})(?:\.[0-9]{1,9})?s$
-          type: string
-          description: Time to wait before dispatching the first activity.
         completionCallbacks:
           type: array
           items:
@@ -14336,7 +14332,9 @@ components:
           type: array
           items:
             $ref: '#/components/schemas/Link'
-          description: Links to be associated with the activity.
+          description: |-
+            Links to be associated with the activity. Callbacks may also have associated links;
+             links already included with a callback should not be duplicated here.
     StartActivityExecutionResponse:
       type: object
       properties:
diff --git a/temporal/api/workflowservice/v1/request_response.proto b/temporal/api/workflowservice/v1/request_response.proto
index f3ecc7ff0..41bda284f 100644
--- a/temporal/api/workflowservice/v1/request_response.proto
+++ b/temporal/api/workflowservice/v1/request_response.proto
@@ -2931,13 +2931,12 @@ message StartActivityExecutionRequest {
     temporal.api.sdk.v1.UserMetadata user_metadata = 17;
     // Priority metadata.
     temporal.api.common.v1.Priority priority = 18;
-    // Time to wait before dispatching the first activity.
-    google.protobuf.Duration start_delay = 19;
     // Callbacks to be called by the server when this activity reaches a terminal state.
     // Callback addresses must be whitelisted in the server's dynamic configuration.
-    repeated temporal.api.common.v1.Callback completion_callbacks = 20;
-    // Links to be associated with the activity.
-    repeated temporal.api.common.v1.Link links = 21;
+    repeated temporal.api.common.v1.Callback completion_callbacks = 19;
+    // Links to be associated with the activity. Callbacks may also have associated links;
+    // links already included with a callback should not be duplicated here.
+    repeated temporal.api.common.v1.Link links = 20;
 }
 
 message StartActivityExecutionResponse {

From 05c3da954e11417d953b066d8ec3be8b9dd2787a Mon Sep 17 00:00:00 2001
From: Fred Tzeng <fred.tzeng@temporal.io>
Date: Thu, 9 Apr 2026 20:03:27 -0700
Subject: [PATCH 7/8] Address PR comments

---
 temporal/api/activity/v1/message.proto        | 38 ++++++++++++++++++-
 temporal/api/history/v1/message.proto         |  2 +-
 .../workflowservice/v1/request_response.proto |  2 +-
 3 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/temporal/api/activity/v1/message.proto b/temporal/api/activity/v1/message.proto
index 004ce6303..05881da31 100644
--- a/temporal/api/activity/v1/message.proto
+++ b/temporal/api/activity/v1/message.proto
@@ -15,6 +15,7 @@ import "google/protobuf/timestamp.proto";
 import "temporal/api/common/v1/message.proto";
 import "temporal/api/deployment/v1/message.proto";
 import "temporal/api/enums/v1/activity.proto";
+import "temporal/api/enums/v1/common.proto";
 import "temporal/api/enums/v1/workflow.proto";
 import "temporal/api/failure/v1/message.proto";
 import "temporal/api/taskqueue/v1/message.proto";
@@ -162,7 +163,7 @@ message ActivityExecutionInfo {
     // Set if activity cancelation was requested.
     string canceled_reason = 32;
 
-    // Links associated with the activity.
+    // Links to related entities, such as the entity that started this activity.
     repeated temporal.api.common.v1.Link links = 33;
 }
 
@@ -198,3 +199,38 @@ message ActivityExecutionListInfo {
     // This field is only populated if the activity is closed.
     google.protobuf.Duration execution_duration = 11;
 }
+
+// CallbackInfo contains the state of an attached activity callback.
+message CallbackInfo {
+    // Trigger for when the activity is closed.
+    message ActivityClosed {}
+
+    message Trigger {
+        oneof variant {
+            ActivityClosed activity_closed = 1;
+        }
+    }
+
+    // Information on how this callback should be invoked (e.g. its URL and type).
+    temporal.api.common.v1.Callback callback = 1;
+    // Trigger for this callback.
+    Trigger trigger = 2;
+    // The time when the callback was registered.
+    google.protobuf.Timestamp registration_time = 3;
+
+    // The current state of the callback.
+    temporal.api.enums.v1.CallbackState state = 4;
+    // The number of attempts made to deliver the callback.
+    // This number represents a minimum bound since the attempt is incremented after the callback request completes.
+    int32 attempt = 5;
+
+    // The time when the last attempt completed.
+    google.protobuf.Timestamp last_attempt_complete_time = 6;
+    // The last attempt's failure, if any.
+    temporal.api.failure.v1.Failure last_attempt_failure = 7;
+    // The time when the next attempt is scheduled.
+    google.protobuf.Timestamp next_attempt_schedule_time = 8;
+
+    // If the state is BLOCKED, blocked reason provides additional information.
+    string blocked_reason = 9;
+}
diff --git a/temporal/api/history/v1/message.proto b/temporal/api/history/v1/message.proto
index cf866fcdd..2ffd893b1 100644
--- a/temporal/api/history/v1/message.proto
+++ b/temporal/api/history/v1/message.proto
@@ -1152,7 +1152,7 @@ message HistoryEvent {
     //  * timer_started_event_attributes - summary represents an identifier for the timer for use by
     //    user interfaces.
     temporal.api.sdk.v1.UserMetadata user_metadata = 301;
-    // Links associated with the event.
+    // Links to related entities, such as the entity that started this event's workflow.
     repeated temporal.api.common.v1.Link links = 302;
     // Server-computed authenticated caller identity associated with this event.
     temporal.api.common.v1.Principal principal = 303;
diff --git a/temporal/api/workflowservice/v1/request_response.proto b/temporal/api/workflowservice/v1/request_response.proto
index 41bda284f..8580b7179 100644
--- a/temporal/api/workflowservice/v1/request_response.proto
+++ b/temporal/api/workflowservice/v1/request_response.proto
@@ -2984,7 +2984,7 @@ message DescribeActivityExecutionResponse {
     bytes long_poll_token = 5;
 
     // Callbacks attached to this activity execution and their current state.
-    repeated temporal.api.workflow.v1.CallbackInfo callbacks = 6;
+    repeated temporal.api.activity.v1.CallbackInfo callbacks = 6;
 }
 
 message PollActivityExecutionRequest {

From 2bc9df1f6dd8114a4d2eda3c3c20d727e9491408 Mon Sep 17 00:00:00 2001
From: Fred Tzeng <fred.tzeng@temporal.io>
Date: Thu, 9 Apr 2026 20:07:28 -0700
Subject: [PATCH 8/8] Update openapi

---
 openapi/openapiv2.json | 168 +++++++++++++++++++++++++++--------------
 openapi/openapiv3.yaml |   7 +-
 2 files changed, 117 insertions(+), 58 deletions(-)

diff --git a/openapi/openapiv2.json b/openapi/openapiv2.json
index 72928a68a..669fc0a29 100644
--- a/openapi/openapiv2.json
+++ b/openapi/openapiv2.json
@@ -9041,13 +9041,9 @@
     }
   },
   "definitions": {
-    "CallbackInfoTrigger": {
+    "CallbackInfoActivityClosed": {
       "type": "object",
-      "properties": {
-        "workflowClosed": {
-          "$ref": "#/definitions/CallbackInfoWorkflowClosed"
-        }
-      }
+      "description": "Trigger for when the activity is closed."
     },
     "CallbackInfoWorkflowClosed": {
       "type": "object",
@@ -11115,6 +11111,113 @@
       },
       "description": "Used to validate the compute config without attaching it to a Worker Deployment Version."
     },
+    "apiActivityV1CallbackInfo": {
+      "type": "object",
+      "properties": {
+        "callback": {
+          "$ref": "#/definitions/v1Callback",
+          "description": "Information on how this callback should be invoked (e.g. its URL and type)."
+        },
+        "trigger": {
+          "$ref": "#/definitions/apiActivityV1CallbackInfoTrigger",
+          "description": "Trigger for this callback."
+        },
+        "registrationTime": {
+          "type": "string",
+          "format": "date-time",
+          "description": "The time when the callback was registered."
+        },
+        "state": {
+          "$ref": "#/definitions/v1CallbackState",
+          "description": "The current state of the callback."
+        },
+        "attempt": {
+          "type": "integer",
+          "format": "int32",
+          "description": "The number of attempts made to deliver the callback.\nThis number represents a minimum bound since the attempt is incremented after the callback request completes."
+        },
+        "lastAttemptCompleteTime": {
+          "type": "string",
+          "format": "date-time",
+          "description": "The time when the last attempt completed."
+        },
+        "lastAttemptFailure": {
+          "$ref": "#/definitions/v1Failure",
+          "description": "The last attempt's failure, if any."
+        },
+        "nextAttemptScheduleTime": {
+          "type": "string",
+          "format": "date-time",
+          "description": "The time when the next attempt is scheduled."
+        },
+        "blockedReason": {
+          "type": "string",
+          "description": "If the state is BLOCKED, blocked reason provides additional information."
+        }
+      },
+      "description": "CallbackInfo contains the state of an attached activity callback."
+    },
+    "apiActivityV1CallbackInfoTrigger": {
+      "type": "object",
+      "properties": {
+        "activityClosed": {
+          "$ref": "#/definitions/CallbackInfoActivityClosed"
+        }
+      }
+    },
+    "apiWorkflowV1CallbackInfo": {
+      "type": "object",
+      "properties": {
+        "callback": {
+          "$ref": "#/definitions/v1Callback",
+          "description": "Information on how this callback should be invoked (e.g. its URL and type)."
+        },
+        "trigger": {
+          "$ref": "#/definitions/apiWorkflowV1CallbackInfoTrigger",
+          "description": "Trigger for this callback."
+        },
+        "registrationTime": {
+          "type": "string",
+          "format": "date-time",
+          "description": "The time when the callback was registered."
+        },
+        "state": {
+          "$ref": "#/definitions/v1CallbackState"
+        },
+        "attempt": {
+          "type": "integer",
+          "format": "int32",
+          "description": "The number of attempts made to deliver the callback.\nThis number represents a minimum bound since the attempt is incremented after the callback request completes."
+        },
+        "lastAttemptCompleteTime": {
+          "type": "string",
+          "format": "date-time",
+          "description": "The time when the last attempt completed."
+        },
+        "lastAttemptFailure": {
+          "$ref": "#/definitions/v1Failure",
+          "description": "The last attempt's failure, if any."
+        },
+        "nextAttemptScheduleTime": {
+          "type": "string",
+          "format": "date-time",
+          "description": "The time when the next attempt is scheduled."
+        },
+        "blockedReason": {
+          "type": "string",
+          "description": "If the state is BLOCKED, blocked reason provides additional information."
+        }
+      },
+      "description": "CallbackInfo contains the state of an attached workflow callback."
+    },
+    "apiWorkflowV1CallbackInfoTrigger": {
+      "type": "object",
+      "properties": {
+        "workflowClosed": {
+          "$ref": "#/definitions/CallbackInfoWorkflowClosed"
+        }
+      }
+    },
     "protobufAny": {
       "type": "object",
       "properties": {
@@ -11287,7 +11390,7 @@
             "type": "object",
             "$ref": "#/definitions/v1Link"
           },
-          "description": "Links associated with the activity."
+          "description": "Links to related entities, such as the entity that started this activity."
         }
       },
       "description": "Information about a standalone activity."
@@ -12131,51 +12234,6 @@
       },
       "description": "Callback to attach to various events in the system, e.g. workflow run completion."
     },
-    "v1CallbackInfo": {
-      "type": "object",
-      "properties": {
-        "callback": {
-          "$ref": "#/definitions/v1Callback",
-          "description": "Information on how this callback should be invoked (e.g. its URL and type)."
-        },
-        "trigger": {
-          "$ref": "#/definitions/CallbackInfoTrigger",
-          "description": "Trigger for this callback."
-        },
-        "registrationTime": {
-          "type": "string",
-          "format": "date-time",
-          "description": "The time when the callback was registered."
-        },
-        "state": {
-          "$ref": "#/definitions/v1CallbackState"
-        },
-        "attempt": {
-          "type": "integer",
-          "format": "int32",
-          "description": "The number of attempts made to deliver the callback.\nThis number represents a minimum bound since the attempt is incremented after the callback request completes."
-        },
-        "lastAttemptCompleteTime": {
-          "type": "string",
-          "format": "date-time",
-          "description": "The time when the last attempt completed."
-        },
-        "lastAttemptFailure": {
-          "$ref": "#/definitions/v1Failure",
-          "description": "The last attempt's failure, if any."
-        },
-        "nextAttemptScheduleTime": {
-          "type": "string",
-          "format": "date-time",
-          "description": "The time when the next attempt is scheduled."
-        },
-        "blockedReason": {
-          "type": "string",
-          "description": "If the state is BLOCKED, blocked reason provides additional information."
-        }
-      },
-      "description": "CallbackInfo contains the state of an attached workflow callback."
-    },
     "v1CallbackState": {
       "type": "string",
       "enum": [
@@ -12909,7 +12967,7 @@
           "type": "array",
           "items": {
             "type": "object",
-            "$ref": "#/definitions/v1CallbackInfo"
+            "$ref": "#/definitions/apiActivityV1CallbackInfo"
           },
           "description": "Callbacks attached to this activity execution and their current state."
         }
@@ -13149,7 +13207,7 @@
           "type": "array",
           "items": {
             "type": "object",
-            "$ref": "#/definitions/v1CallbackInfo"
+            "$ref": "#/definitions/apiWorkflowV1CallbackInfo"
           }
         },
         "pendingNexusOperations": {
@@ -13731,7 +13789,7 @@
             "type": "object",
             "$ref": "#/definitions/v1Link"
           },
-          "description": "Links associated with the event."
+          "description": "Links to related entities, such as the entity that started this event's workflow."
         },
         "principal": {
           "$ref": "#/definitions/v1Principal",
diff --git a/openapi/openapiv3.yaml b/openapi/openapiv3.yaml
index 25ab730d7..b658789ca 100644
--- a/openapi/openapiv3.yaml
+++ b/openapi/openapiv3.yaml
@@ -8240,7 +8240,7 @@ components:
           type: array
           items:
             $ref: '#/components/schemas/Link'
-          description: Links associated with the activity.
+          description: Links to related entities, such as the entity that started this activity.
       description: Information about a standalone activity.
     ActivityExecutionListInfo:
       type: object
@@ -9089,6 +9089,7 @@ components:
             - CALLBACK_STATE_SUCCEEDED
             - CALLBACK_STATE_BLOCKED
           type: string
+          description: The current state of the callback.
           format: enum
         attempt:
           type: integer
@@ -9111,7 +9112,7 @@ components:
         blockedReason:
           type: string
           description: If the state is BLOCKED, blocked reason provides additional information.
-      description: CallbackInfo contains the state of an attached workflow callback.
+      description: CallbackInfo contains the state of an attached activity callback.
     CallbackInfo_Trigger:
       type: object
       properties:
@@ -10740,7 +10741,7 @@ components:
           type: array
           items:
             $ref: '#/components/schemas/Link'
-          description: Links associated with the event.
+          description: Links to related entities, such as the entity that started this event's workflow.
         principal:
           allOf:
             - $ref: '#/components/schemas/Principal'