Use ordered SQLite migrations (Refs #75)

src/lib/server/hosts/calibration.ts

@@ -1,6 +1,5 @@
 import { fleetSettings } from '../settings.js';
 import { db } from '../db/index.js';
-import { ensureHostSchema } from './schema.js';
 import type {
     CapacityCalibration,
     CapacitySample,
@@ -25,9 +24,7 @@ interface AllowanceRow {
     computed_at: string;
 }
 function database() {
-    const handle = db();
-    ensureHostSchema(handle);
-    return handle;
+    return db();
 }
 
 /** Read retained minute peaks without contacting agents or recalculating allowances. */

src/lib/server/hosts/capacity-history.ts

@@ -1,5 +1,4 @@
 import { db } from '../db/index.js';
-import { ensureHostSchema } from './schema.js';
 import type { CapacityHistory, CapacityQuery, CapacityRange } from '../../capacity.js';
 
 const windows: Record<CapacityRange, { duration: number; bucketMs: number }> = {
@@ -11,7 +10,6 @@ const windows: Record<CapacityRange, { duration: number; bucketMs: number }> = {
 /** Read on the report worker: heartbeat history can contain millions of rows. */
 export function readCapacityHistory(query: CapacityQuery, now = Date.now()): CapacityHistory {
     const handle = db();
-    ensureHostSchema(handle);
     const { duration, bucketMs } = windows[query.range];
     const startAt = now - duration;
     const count = duration / bucketMs;

src/lib/server/hosts/index.ts

@@ -5,7 +5,6 @@ import { EventEmitter } from 'node:events';
 import { createHash, randomBytes, randomUUID, timingSafeEqual } from 'node:crypto';
 import { isIP } from 'node:net';
 import { db } from '../db/index.js';
-import { ensureHostSchema } from './schema.js';
 import {
     successfulObservation,
     routineObservationSql,
@@ -60,9 +59,7 @@ export function waitForHostWork(
 }
 const digest = (token: string) => createHash('sha256').update(token).digest('hex');
 function database() {
-    const handle = db();
-    ensureHostSchema(handle);
-    return handle;
+    return db();
 }
 type HostRow = {
     id: string;

src/lib/server/hosts/schema.ts

@@ -7,7 +7,6 @@ import {
 } from '../db/file-blobs.js';
 import { retentionClocks } from '../db/retention-clocks.js';
 import { installHistoryCounts } from './history-counts.js';
-import { migrationStep } from '../db/connection.js';
 import type Database from 'better-sqlite3';
 import {
     successfulObservationSql,
@@ -16,19 +15,7 @@ import {
     importantOperationSql
 } from './observations.js';
 
-const initialized = new WeakSet<Database.Database>();
-export function ensureHostSchema(handle: Database.Database): void {
-    if (initialized.has(handle)) return;
-    // Background readers open only after controller migrations have completed.
-    if (handle.readonly) {
-        initialized.add(handle);
-        return;
-    }
-    migrationStep('host schema and saved command files', () => migrateHostSchema(handle));
-    initialized.add(handle);
-}
-
-function migrateHostSchema(handle: Database.Database): void {
+export function migrateHostSchema(handle: Database.Database): void {
     ensureFileBlobSchema(handle);
     handle.exec(`
         CREATE TABLE IF NOT EXISTS ec_hosts (