feat(export): implement chunked R2 database export with DO alarm cont…

src/do.ts

@@ -1,4 +1,5 @@
 import { DurableObject } from 'cloudflare:workers'
+import type { ExportState } from './export/chunked-dump'
 
 export class StarbaseDBDurableObject extends DurableObject {
     // Durable storage for the SQL database
@@ -72,9 +73,46 @@ export class StarbaseDBDurableObject extends DurableObject {
             deleteAlarm: this.deleteAlarm.bind(this),
             getStatistics: this.getStatistics.bind(this),
             executeQuery: this.executeQuery.bind(this),
+            saveExportState: this.saveExportState.bind(this),
+            getExportState: this.getExportState.bind(this),
+            getActiveExportState: this.getActiveExportState.bind(this),
         }
     }
 
+    /**
+     * Save export state to DO storage for resumption after alarm.
+     */
+    public async saveExportState(state: ExportState): Promise<void> {
+        await this.storage.put(
+            `export:${state.exportId}`,
+            JSON.stringify(state)
+        )
+        // Also track the active export (only one at a time)
+        if (state.status === 'processing') {
+            await this.storage.put('export:active', state.exportId)
+        } else {
+            await this.storage.delete('export:active')
+        }
+    }
+
+    /**
+     * Get export state by export ID.
+     */
+    public async getExportState(exportId: string): Promise<ExportState | null> {
+        const raw = await this.storage.get<string>(`export:${exportId}`)
+        if (!raw) return null
+        return JSON.parse(raw) as ExportState
+    }
+
+    /**
+     * Get the currently active (in-progress) export state, if any.
+     */
+    public async getActiveExportState(): Promise<ExportState | null> {
+        const activeId = await this.storage.get<string>('export:active')
+        if (!activeId) return null
+        return this.getExportState(activeId)
+    }
+
     public async getAlarm(): Promise<number | null> {
         return await this.storage.getAlarm()
     }
@@ -106,6 +144,33 @@ export class StarbaseDBDurableObject extends DurableObject {
 
     async alarm() {
         try {
+            // Check if there's an active export to continue
+            const activeExport = await this.getActiveExportState()
+            if (activeExport && activeExport.status === 'processing') {
+                // The actual export continuation is handled by the Worker
+                // via a fetch to a special internal path
+                try {
+                    await fetch(`https://localhost/internal/export/continue`, {
+                        method: 'POST',
+                        headers: {
+                            Authorization: `Bearer ${this.clientAuthToken}`,
+                            'Content-Type': 'application/json',
+                        },
+                        body: JSON.stringify({
+                            exportId: activeExport.exportId,
+                        }),
+                    })
+                } catch (error) {
+                    console.error('Failed to continue export via alarm:', error)
+                    // Mark export as failed if we can't continue
+                    activeExport.status = 'failed'
+                    activeExport.error = 'Alarm continuation failed'
+                    activeExport.updatedAt = Date.now()
+                    await this.saveExportState(activeExport)
+                }
+                return
+            }
+
             // Fetch all the tasks that are marked to emit an event for this cycle.
             const task = (await this.executeQuery({
                 sql: 'SELECT * FROM tmp_cron_tasks WHERE is_active = 1;',