feat(KB-635): add mission management CLI commands and engine integration

- Add comprehensive mission CLI commands: create, list, show, start, abort, delete, and next
- Add Pi extension tools for mission operations: list_missions, show_mission, start_mission, abort_mission
- Implement mission-aware scheduler with task start handling and autoAdvance support
- Add sliceId to Task type and autoAdvance flag to Mission type for slice sequencing
- Add MissionStore helper methods for mission lifecycle operations
- Include comprehensive tests for CLI commands and Pi extension mission tools

packages/core/src/mission-store.ts

@@ -725,6 +725,29 @@ export class MissionStore extends EventEmitter<MissionStoreEvents> {
     return updated;
   }
 
+  /**
+   * Find the next pending slice in a mission.
+   * Iterates milestones by orderIndex, then slices by orderIndex,
+   * and returns the first slice with status "pending".
+   *
+   * @param missionId - Mission ID
+   * @returns The next pending slice, or undefined if none found
+   */
+  findNextPendingSlice(missionId: string): Slice | undefined {
+    const milestones = this.listMilestones(missionId);
+
+    for (const milestone of milestones) {
+      const slices = this.listSlices(milestone.id);
+      for (const slice of slices) {
+        if (slice.status === "pending") {
+          return slice;
+        }
+      }
+    }
+
+    return undefined;
+  }
+
   // ── Feature Operations ─────────────────────────────────────────────
 
   /**
@@ -929,6 +952,29 @@ export class MissionStore extends EventEmitter<MissionStoreEvents> {
     return updated;
   }
 
+  /**
+   * Update a feature's status.
+   * Recomputes slice status after update.
+   *
+   * @param featureId - Feature ID
+   * @param status - New status
+   * @returns The updated feature
+   * @throws Error if feature not found
+   */
+  updateFeatureStatus(featureId: string, status: FeatureStatus): MissionFeature {
+    const feature = this.getFeature(featureId);
+    if (!feature) {
+      throw new Error(`Feature ${featureId} not found`);
+    }
+
+    const updated = this.updateFeature(featureId, { status });
+
+    // Recompute slice status
+    this.recomputeSliceStatus(updated.sliceId);
+
+    return updated;
+  }
+
   /**
    * Find a feature by its linked task ID.
    *

packages/core/src/mission-types.ts

@@ -48,6 +48,8 @@ export interface Mission {
   status: MissionStatus;
   /** State of the AI specification interview process */
   interviewState: InterviewState;
+  /** When true, automatically activate the next pending slice when current slice completes */
+  autoAdvance?: boolean;
   /** ISO-8601 timestamp of creation */
   createdAt: string;
   /** ISO-8601 timestamp of last update */

packages/core/src/types.ts

@@ -434,6 +434,8 @@ export interface Task {
   summary?: string;
   /** Files modified during agent execution, captured at task completion time */
   modifiedFiles?: string[];
+  /** Optional ID of the slice this task is linked to (for mission-based work) */
+  sliceId?: string;
   /** ISO-8601 timestamp of when the task last entered its current column.
    *  Used to sort cards within a column so that recently-moved cards appear at the top. */
   columnMovedAt?: string;