feat(plugins): define TaskWorker capability for task execution callbacks

plugins/capabilities/taskworker.go

@@ -0,0 +1,33 @@
+package capabilities
+
+// TaskWorker provides task execution handling.
+// This capability allows plugins to receive callbacks when their queued tasks
+// are ready to execute. Plugins that use the taskqueue host service must
+// implement this capability.
+//
+//nd:capability name=taskworker
+type TaskWorker interface {
+	// OnTaskExecute is called when a queued task is ready to run.
+	// Return an error to trigger retry (if retries are configured).
+	//nd:export name=nd_task_execute
+	OnTaskExecute(TaskExecuteRequest) (TaskExecuteResponse, error)
+}
+
+// TaskExecuteRequest is the request provided when a task is ready to execute.
+type TaskExecuteRequest struct {
+	// QueueName is the name of the queue this task belongs to.
+	QueueName string `json:"queueName"`
+	// TaskID is the unique identifier for this task.
+	TaskID string `json:"taskId"`
+	// Payload is the opaque data provided when the task was enqueued.
+	Payload []byte `json:"payload"`
+	// Attempt is the current attempt number (1-based: first attempt = 1).
+	Attempt int32 `json:"attempt"`
+}
+
+// TaskExecuteResponse is the response from task execution.
+type TaskExecuteResponse struct {
+	// Error, if non-empty, indicates the task failed. The task will be retried
+	// if retries are configured and attempts remain.
+	Error string `json:"error,omitempty"`
+}

plugins/capabilities/taskworker.yaml

@@ -0,0 +1,45 @@
+version: v1-draft
+exports:
+    nd_task_execute:
+        description: |-
+            OnTaskExecute is called when a queued task is ready to run.
+            Return an error to trigger retry (if retries are configured).
+        input:
+            $ref: '#/components/schemas/TaskExecuteRequest'
+            contentType: application/json
+        output:
+            $ref: '#/components/schemas/TaskExecuteResponse'
+            contentType: application/json
+components:
+    schemas:
+        TaskExecuteRequest:
+            description: TaskExecuteRequest is the request provided when a task is ready to execute.
+            properties:
+                queueName:
+                    type: string
+                    description: QueueName is the name of the queue this task belongs to.
+                taskId:
+                    type: string
+                    description: TaskID is the unique identifier for this task.
+                payload:
+                    type: array
+                    description: Payload is the opaque data provided when the task was enqueued.
+                    items:
+                        type: object
+                attempt:
+                    type: integer
+                    format: int32
+                    description: 'Attempt is the current attempt number (1-based: first attempt = 1).'
+            required:
+                - queueName
+                - taskId
+                - payload
+                - attempt
+        TaskExecuteResponse:
+            description: TaskExecuteResponse is the response from task execution.
+            properties:
+                error:
+                    type: string
+                    description: |-
+                        Error, if non-empty, indicates the task failed. The task will be retried
+                        if retries are configured and attempts remain.

plugins/pdk/go/taskworker/taskworker.go

@@ -0,0 +1,86 @@
+// Code generated by ndpgen. DO NOT EDIT.
+//
+// This file contains export wrappers for the TaskWorker capability.
+// It is intended for use in Navidrome plugins built with TinyGo.
+//
+//go:build wasip1
+
+package taskworker
+
+import (
+	"github.com/navidrome/navidrome/plugins/pdk/go/pdk"
+)
+
+// TaskExecuteRequest is the request provided when a task is ready to execute.
+type TaskExecuteRequest struct {
+	// QueueName is the name of the queue this task belongs to.
+	QueueName string `json:"queueName"`
+	// TaskID is the unique identifier for this task.
+	TaskID string `json:"taskId"`
+	// Payload is the opaque data provided when the task was enqueued.
+	Payload []byte `json:"payload"`
+	// Attempt is the current attempt number (1-based: first attempt = 1).
+	Attempt int32 `json:"attempt"`
+}
+
+// TaskExecuteResponse is the response from task execution.
+type TaskExecuteResponse struct {
+	// Error, if non-empty, indicates the task failed. The task will be retried
+	// if retries are configured and attempts remain.
+	Error string `json:"error,omitempty"`
+}
+
+// TaskWorker is the marker interface for taskworker plugins.
+// Implement one or more of the provider interfaces below.
+// TaskWorker provides task execution handling.
+// This capability allows plugins to receive callbacks when their queued tasks
+// are ready to execute. Plugins that use the taskqueue host service must
+// implement this capability.
+type TaskWorker interface{}
+
+// TaskExecuteProvider provides the OnTaskExecute function.
+type TaskExecuteProvider interface {
+	OnTaskExecute(TaskExecuteRequest) (TaskExecuteResponse, error)
+} // Internal implementation holders
+var (
+	taskExecuteImpl func(TaskExecuteRequest) (TaskExecuteResponse, error)
+)
+
+// Register registers a taskworker implementation.
+// The implementation is checked for optional provider interfaces.
+func Register(impl TaskWorker) {
+	if p, ok := impl.(TaskExecuteProvider); ok {
+		taskExecuteImpl = p.OnTaskExecute
+	}
+}
+
+// NotImplementedCode is the standard return code for unimplemented functions.
+// The host recognizes this and skips the plugin gracefully.
+const NotImplementedCode int32 = -2
+
+//go:wasmexport nd_task_execute
+func _NdTaskExecute() int32 {
+	if taskExecuteImpl == nil {
+		// Return standard code - host will skip this plugin gracefully
+		return NotImplementedCode
+	}
+
+	var input TaskExecuteRequest
+	if err := pdk.InputJSON(&input); err != nil {
+		pdk.SetError(err)
+		return -1
+	}
+
+	output, err := taskExecuteImpl(input)
+	if err != nil {
+		pdk.SetError(err)
+		return -1
+	}
+
+	if err := pdk.OutputJSON(output); err != nil {
+		pdk.SetError(err)
+		return -1
+	}
+
+	return 0
+}

plugins/pdk/go/taskworker/taskworker_stub.go

@@ -0,0 +1,48 @@
+// Code generated by ndpgen. DO NOT EDIT.
+//
+// This file provides stub implementations for non-WASM platforms.
+// It allows Go plugins to compile and run tests outside of WASM,
+// but the actual functionality is only available in WASM builds.
+//
+//go:build !wasip1
+
+package taskworker
+
+// TaskExecuteRequest is the request provided when a task is ready to execute.
+type TaskExecuteRequest struct {
+	// QueueName is the name of the queue this task belongs to.
+	QueueName string `json:"queueName"`
+	// TaskID is the unique identifier for this task.
+	TaskID string `json:"taskId"`
+	// Payload is the opaque data provided when the task was enqueued.
+	Payload []byte `json:"payload"`
+	// Attempt is the current attempt number (1-based: first attempt = 1).
+	Attempt int32 `json:"attempt"`
+}
+
+// TaskExecuteResponse is the response from task execution.
+type TaskExecuteResponse struct {
+	// Error, if non-empty, indicates the task failed. The task will be retried
+	// if retries are configured and attempts remain.
+	Error string `json:"error,omitempty"`
+}
+
+// TaskWorker is the marker interface for taskworker plugins.
+// Implement one or more of the provider interfaces below.
+// TaskWorker provides task execution handling.
+// This capability allows plugins to receive callbacks when their queued tasks
+// are ready to execute. Plugins that use the taskqueue host service must
+// implement this capability.
+type TaskWorker interface{}
+
+// TaskExecuteProvider provides the OnTaskExecute function.
+type TaskExecuteProvider interface {
+	OnTaskExecute(TaskExecuteRequest) (TaskExecuteResponse, error)
+}
+
+// NotImplementedCode is the standard return code for unimplemented functions.
+const NotImplementedCode int32 = -2
+
+// Register is a no-op on non-WASM platforms.
+// This stub allows code to compile outside of WASM.
+func Register(_ TaskWorker) {}

plugins/pdk/rust/nd-pdk-capabilities/src/lib.rs

@@ -9,4 +9,5 @@ pub mod lifecycle;
 pub mod metadata;
 pub mod scheduler;
 pub mod scrobbler;
+pub mod taskworker;
 pub mod websocket;

plugins/pdk/rust/nd-pdk-capabilities/src/taskworker.rs

@@ -0,0 +1,87 @@
+// Code generated by ndpgen. DO NOT EDIT.
+//
+// This file contains export wrappers for the TaskWorker capability.
+// It is intended for use in Navidrome plugins built with extism-pdk.
+
+use serde::{Deserialize, Serialize};
+
+// Helper functions for skip_serializing_if with numeric types
+#[allow(dead_code)]
+fn is_zero_i32(value: &i32) -> bool { *value == 0 }
+#[allow(dead_code)]
+fn is_zero_u32(value: &u32) -> bool { *value == 0 }
+#[allow(dead_code)]
+fn is_zero_i64(value: &i64) -> bool { *value == 0 }
+#[allow(dead_code)]
+fn is_zero_u64(value: &u64) -> bool { *value == 0 }
+#[allow(dead_code)]
+fn is_zero_f32(value: &f32) -> bool { *value == 0.0 }
+#[allow(dead_code)]
+fn is_zero_f64(value: &f64) -> bool { *value == 0.0 }
+/// TaskExecuteRequest is the request provided when a task is ready to execute.
+#[derive(Debug, Clone, Default, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct TaskExecuteRequest {
+    /// QueueName is the name of the queue this task belongs to.
+    #[serde(default)]
+    pub queue_name: String,
+    /// TaskID is the unique identifier for this task.
+    #[serde(default)]
+    pub task_id: String,
+    /// Payload is the opaque data provided when the task was enqueued.
+    #[serde(default)]
+    pub payload: Vec<u8>,
+    /// Attempt is the current attempt number (1-based: first attempt = 1).
+    #[serde(default)]
+    pub attempt: i32,
+}
+/// TaskExecuteResponse is the response from task execution.
+#[derive(Debug, Clone, Default, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct TaskExecuteResponse {
+    /// Error, if non-empty, indicates the task failed. The task will be retried
+    /// if retries are configured and attempts remain.
+    #[serde(default, skip_serializing_if = "String::is_empty")]
+    pub error: String,
+}
+
+/// Error represents an error from a capability method.
+#[derive(Debug)]
+pub struct Error {
+    pub message: String,
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.message)
+    }
+}
+
+impl std::error::Error for Error {}
+
+impl Error {
+    pub fn new(message: impl Into<String>) -> Self {
+        Self { message: message.into() }
+    }
+}
+
+/// TaskExecuteProvider provides the OnTaskExecute function.
+pub trait TaskExecuteProvider {
+    fn on_task_execute(&self, req: TaskExecuteRequest) -> Result<TaskExecuteResponse, Error>;
+}
+
+/// Register the on_task_execute export.
+/// This macro generates the WASM export function for this method.
+#[macro_export]
+macro_rules! register_taskworker_task_execute {
+    ($plugin_type:ty) => {
+        #[extism_pdk::plugin_fn]
+        pub fn nd_task_execute(
+            req: extism_pdk::Json<$crate::taskworker::TaskExecuteRequest>
+        ) -> extism_pdk::FnResult<extism_pdk::Json<$crate::taskworker::TaskExecuteResponse>> {
+            let plugin = <$plugin_type>::default();
+            let result = $crate::taskworker::TaskExecuteProvider::on_task_execute(&plugin, req.into_inner())?;
+            Ok(extism_pdk::Json(result))
+        }
+    };
+}