FN-5703: forward task:deleted events through in-process runtime

Ensure engine-side task deletes propagate through all runtime transports so GitHub tracking cleanup runs consistently.

- extend IPC protocol and child-process runtime/worker plumbing to carry `task:deleted` events
- forward `task:deleted` from in-process runtime through project runtime and project manager dispatch
- add regression coverage for in-process runtime forwarding and GitHub tracking delete handling

Files changed:
 .../src/__tests__/github-tracking-delete.test.ts   | 29 ++++++++++++++++++
 .../src/__tests__/in-process-runtime.test.ts       | 34 +++++++++++++++++++++-
 packages/engine/src/ipc/ipc-protocol.ts            | 14 ++++++++-
 packages/engine/src/project-manager.ts             |  7 +++++
 packages/engine/src/project-runtime.ts             |  4 ++-
 .../engine/src/runtimes/child-process-runtime.ts   |  6 ++++
 .../engine/src/runtimes/child-process-worker.ts    | 14 +++++++--
 packages/engine/src/runtimes/in-process-runtime.ts | 10 ++++++-
 8 files changed, 111 insertions(+), 7 deletions(-)

Fusion-Task-Id: FN-5703

Fusion-Task-Lineage: 1406838b-5abf-4b86-8161-c2dd59f88a9b

packages/engine/src/runtimes/child-process-runtime.ts

@@ -22,11 +22,13 @@ import {
   TASK_CREATED,
   TASK_MOVED,
   TASK_UPDATED,
+  TASK_DELETED,
   ERROR_EVENT,
   HEALTH_CHANGED,
   type TaskCreatedPayload,
   type TaskMovedPayload,
   type TaskUpdatedPayload,
+  type TaskDeletedPayload,
   type ErrorEventPayload,
   type HealthChangedPayload,
 } from "../ipc/ipc-protocol.js";
@@ -296,6 +298,10 @@ export class ChildProcessRuntime
       this.emit("task:updated", payload.task);
     });
 
+    this.ipcHost.on(TASK_DELETED, (payload: TaskDeletedPayload) => {
+      this.emit("task:deleted", payload.task, payload.meta);
+    });
+
     // Forward error events
     this.ipcHost.on(ERROR_EVENT, (payload: ErrorEventPayload) => {
       const error = new Error(payload.message);

packages/engine/src/runtimes/child-process-worker.ts

@@ -18,6 +18,10 @@ import {
   STOP_RUNTIME,
   GET_STATUS,
   GET_METRICS,
+  TASK_CREATED,
+  TASK_MOVED,
+  TASK_UPDATED,
+  TASK_DELETED,
   ERROR_EVENT,
   type StartRuntimePayload,
 } from "../ipc/ipc-protocol.js";
@@ -76,15 +80,19 @@ ipcWorker.onCommand(START_RUNTIME, async (payload: unknown) => {
 
   // Forward runtime events to host
   runtime.on("task:created", (task) => {
-    ipcWorker.sendEvent("TASK_CREATED", { task });
+    ipcWorker.sendEvent(TASK_CREATED, { task });
   });
 
   runtime.on("task:moved", (data) => {
-    ipcWorker.sendEvent("TASK_MOVED", data);
+    ipcWorker.sendEvent(TASK_MOVED, data);
   });
 
   runtime.on("task:updated", (task) => {
-    ipcWorker.sendEvent("TASK_UPDATED", { task });
+    ipcWorker.sendEvent(TASK_UPDATED, { task });
+  });
+
+  runtime.on("task:deleted", (task, meta) => {
+    ipcWorker.sendEvent(TASK_DELETED, { task, meta });
   });
 
   runtime.on("error", (error) => {

packages/engine/src/runtimes/in-process-runtime.ts

@@ -10,6 +10,7 @@ import type {
   PluginLoader,
   MessageStore,
   RoutineStore,
+  GithubIssueAction,
 } from "@fusion/core";
 import { ChatStore, createCentralDatabase, isEphemeralAgent } from "@fusion/core";
 import { Scheduler } from "../scheduler.js";
@@ -1284,7 +1285,8 @@ export class InProcessRuntime
   }
 
   /**
-   * Set up event forwarding from TaskStore to runtime listeners.
+   * Set up event forwarding from TaskStore to runtime listeners
+   * for task:created, task:moved, task:updated, and task:deleted.
    */
   private setupEventForwarding(): void {
     // Forward task:created events
@@ -1305,6 +1307,12 @@ export class InProcessRuntime
       this.emit("task:updated", task);
     });
 
+    // Forward task:deleted events
+    this.taskStore.on("task:deleted", (task: Task, meta?: { githubIssueAction?: GithubIssueAction }) => {
+      this.recordActivity();
+      this.emit("task:deleted", task, meta);
+    });
+
     runtimeLog.log("Event forwarding setup complete");
   }