fix(automation): record-change flows see multi-lookup fields + array-index interpolation (#1872)

A `multiple: true` lookup is an array column a driver may not echo back on
create, so it was absent from the after-create record a record-change flow saw:
`record.target_channels != null` was false and `{rec.target_channels.0}`
resolved empty. (Multi-lookup is an array column, not a junction table.)

Two parts:
- trigger-record-change buildContext: read the hook's `input.data` (objectql's
  actual insert/update payload key — it had been reading a non-existent
  `input.doc`, so the input fallback never worked) and overlay the after-row on
  it, so fields the driver didn't return stay visible to the flow's start
  condition and `{record.<field>}` interpolation.
- service-automation template: `{var.path.N}` numeric segments index into arrays
  (`{record.channels.0}`).

Tests: full-kernel repro (driver that doesn't echo the array column → flow fires
on the multi-lookup condition AND stamps `{record.target_channels.0}`) +
array-index interpolation unit tests. service-automation 199, trigger 20 pass
(incl. the #1491 integration test, confirming the input.data change is safe).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: os-zhuang

.changeset/multilookup-record-change-context.md

@@ -0,0 +1,18 @@
+---
+"@objectstack/trigger-record-change": patch
+"@objectstack/service-automation": patch
+---
+
+fix(automation): record-change flows see multi-lookup fields + support array-index interpolation (#1872)
+
+A `multiple: true` lookup is an array column the data driver may not echo back
+on create, so it was absent from the after-create record a record-change flow
+saw — `record.target_channels != null` was false and `{rec.target_channels.0}`
+resolved empty. Two fixes:
+
+- **trigger-record-change**: `buildContext` now reads the lifecycle hook's
+  `input.data` (the actual key objectql uses for insert/update; it had been
+  reading a non-existent `input.doc`) and overlays the after-row on it, so fields
+  the driver didn't return stay visible to the flow's condition + interpolation.
+- **service-automation**: `{var.path.N}` numeric segments now index into arrays,
+  so a multi-value lookup can be referenced positionally (`{record.channels.0}`).

packages/services/service-automation/src/builtin/template-array-index.test.ts

@@ -0,0 +1,32 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * #1872 — `{var.path.N}` numeric segments index into arrays, so a multi-value
+ * lookup (array column) can be referenced positionally in flow interpolation.
+ */
+import { describe, it, expect } from 'vitest';
+import { interpolateString } from './template.js';
+
+const ctx = {} as any;
+const vars = new Map<string, unknown>([
+  ['record', { items: ['a', 'b', 'c'], target_channels: ['ch_1', 'ch_2'] }],
+  ['list', ['x', 'y']],
+]);
+
+describe('interpolate array-index segments (#1872)', () => {
+  it('resolves a single-token array index, preserving type', () => {
+    expect(interpolateString('{record.items.0}', vars, ctx)).toBe('a');
+    expect(interpolateString('{record.items.2}', vars, ctx)).toBe('c');
+    expect(interpolateString('{record.target_channels.0}', vars, ctx)).toBe('ch_1');
+    expect(interpolateString('{list.1}', vars, ctx)).toBe('y');
+  });
+
+  it('resolves an array index embedded in a larger string', () => {
+    expect(interpolateString('first={record.items.0};second={record.items.1}', vars, ctx)).toBe('first=a;second=b');
+  });
+
+  it('out-of-range index yields undefined (single) / empty (embedded)', () => {
+    expect(interpolateString('{record.items.9}', vars, ctx)).toBeUndefined();
+    expect(interpolateString('x={record.items.9}', vars, ctx)).toBe('x=');
+  });
+});

packages/services/service-automation/src/builtin/template.ts

@@ -7,6 +7,7 @@
  *
  *   {variable}                → variables.get('variable')
  *   {variable.path.segment}   → walks dotted path on the resolved value
+ *   {list.0} / {rec.items.2}   → numeric segments index into arrays
  *   {$User.Id}                → reads from context.userId
  *   {$User.Email}             → reads from context.user?.email
  *   {NOW()}                   → ISO timestamp at evaluation time
@@ -78,7 +79,9 @@ function resolveToken(token: string, variables: VariableMap, context: Automation
     }
 
     // Direct variable / dotted path lookup (fast path, no arithmetic).
-    if (/^[A-Za-z_$][\w$]*(?:\.[A-Za-z_$][\w$]*)*$/.test(trimmed)) {
+    // Path segments after the head may be identifiers OR array indices (`\d+`),
+    // so `{list.0}` / `{record.target_channels.0}` resolve into arrays (#1872).
+    if (/^[A-Za-z_$][\w$]*(?:\.(?:[A-Za-z_$][\w$]*|\d+))*$/.test(trimmed)) {
         const segments = trimmed.split('.');
         const head = segments[0];
         if (variables.has(head)) {

packages/triggers/trigger-record-change/src/multilookup-context.test.ts

@@ -0,0 +1,96 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * #1872 — a multi-value (`multiple: true`) lookup is an array column the driver
+ * may not echo back on create, so it was absent from the after-create record the
+ * record-change flow sees (condition / interpolation on it resolved empty). The
+ * trigger now merges the input doc under the after-row so fields the driver
+ * didn't return are still available.
+ */
+import { describe, it, expect } from 'vitest';
+import { ObjectKernel } from '@objectstack/core';
+import { ObjectQLPlugin } from '@objectstack/objectql';
+import { AutomationServicePlugin, type AutomationEngine } from '@objectstack/service-automation';
+import { RecordChangeTriggerPlugin } from './plugin.js';
+
+const sleep = (ms: number) => new Promise((r) => setTimeout(r, ms));
+
+/** Memory driver whose create() does NOT echo `target_channels` (simulates a
+ *  driver that doesn't return the multi-lookup array column). */
+function makeDriver(): any {
+  const store = new Map<string, Record<string, unknown>>();
+  let n = 0;
+  const matches = (row: any, where: any): boolean => {
+    if (!where || typeof where !== 'object') return true;
+    for (const [k, v] of Object.entries(where)) {
+      if (k.startsWith('$')) continue;
+      const exp = v && typeof v === 'object' && '$eq' in (v as any) ? (v as any).$eq : v;
+      if ((row[k] ?? null) !== (exp ?? null)) return false;
+    }
+    return true;
+  };
+  return {
+    name: 'memory', version: '0', supports: {},
+    async connect() {}, async disconnect() {}, async checkHealth() { return true; },
+    async execute() { return null; }, async syncSchema() {},
+    async create(_o: string, data: any) {
+      n += 1; const id = data.id ?? `r_${n}`;
+      const full = { ...data, id };
+      store.set(id, full);
+      // Echo everything EXCEPT the multi-lookup column (the #1872 gap).
+      const { target_channels, ...echoed } = full;
+      return echoed;
+    },
+    async update(_o: string, id: string, data: any) { const cur = store.get(id) ?? {}; const u = { ...cur, ...data, id }; store.set(id, u); return u; },
+    async find(_o: string, ast: any) { return [...store.values()].filter((r) => matches(r, ast?.where)); },
+    async findOne(_o: string, ast: any) { for (const r of store.values()) if (matches(r, ast?.where)) return r; return null; },
+    async delete(_o: string, id: string) { return store.delete(id); },
+    async count(_o: string, ast: any) { return (await this.find(_o, ast)).length; },
+    async upsert(_o: string, d: any) { return this.create(_o, d); },
+    async bulkCreate(_o: string, rows: any[]) { return Promise.all(rows.map((r) => this.create(_o, r))); },
+    async bulkUpdate() { return []; }, async bulkDelete() {},
+    async beginTransaction() { return { commit: async () => {}, rollback: async () => {} }; },
+    async commit() {}, async rollback() {},
+  };
+}
+
+describe('record-change context hydrates multi-lookup from input (#1872)', () => {
+  it('fires a record-after-create flow gated on a multi-lookup the driver did not echo', async () => {
+    const kernel = new ObjectKernel({ logLevel: 'silent' });
+    await kernel.use(new ObjectQLPlugin());
+    await kernel.use(new AutomationServicePlugin());
+    await kernel.use(new RecordChangeTriggerPlugin());
+    await kernel.bootstrap();
+
+    const objectql = kernel.getService('objectql') as any;
+    const data = kernel.getService('data') as any;
+    const automation = kernel.getService<AutomationEngine>('automation');
+    objectql.registerDriver(makeDriver(), true);
+    objectql.registry.registerObject({
+      name: 'piece', label: 'Piece',
+      fields: {
+        title: { name: 'title', label: 'T', type: 'text' },
+        target_channels: { name: 'target_channels', label: 'Ch', type: 'lookup', reference: 'channel', multiple: true },
+        stamp: { name: 'stamp', label: 'S', type: 'text' },
+      },
+    }, 'test', 'test');
+
+    automation.registerFlow('cta_default', {
+      name: 'cta_default', label: 'CTA', type: 'autolaunched',
+      nodes: [
+        { id: 'start', type: 'start', label: 'Start', config: { objectName: 'piece', triggerType: 'record-after-create', condition: 'record.target_channels != null' } },
+        { id: 'stamp', type: 'update_record', label: 'Stamp', config: { objectName: 'piece', filter: { id: '{record.id}' }, fields: { stamp: '{record.target_channels.0}' } } },
+        { id: 'end', type: 'end', label: 'End' },
+      ],
+      edges: [ { id: 'e1', source: 'start', target: 'stamp' }, { id: 'e2', source: 'stamp', target: 'end' } ],
+    } as any);
+
+    const created = await data.insert('piece', { title: 'X', target_channels: ['ch_1', 'ch_2'] });
+    const id = Array.isArray(created) ? created[0]?.id : created?.id ?? created;
+    await sleep(200);
+    const row = await data.findOne('piece', { where: { id } });
+    console.log('[dbg] row=', JSON.stringify(row));
+    // Flow fired (condition saw target_channels) AND `{record.target_channels.0}` resolved.
+    expect(row?.stamp).toBe('ch_1');
+  }, 15000);
+});

packages/triggers/trigger-record-change/src/record-change-trigger.ts

@@ -155,21 +155,32 @@ export class RecordChangeTrigger implements FlowTrigger {
      * (with the `__previous` stash audit also uses as a fallback).
      */
     private buildContext(binding: FlowTriggerBinding, ctx: HookContext): AutomationContext {
-        const input = (ctx.input ?? {}) as { doc?: Record<string, unknown>; id?: unknown };
+        // objectql lifecycle hooks carry the written row under `input.data` (insert /
+        // update payload); `id` is on update. (`doc` kept only as a defensive alias.)
+        const input = (ctx.input ?? {}) as { data?: Record<string, unknown>; doc?: Record<string, unknown>; id?: unknown };
         const after = ctx.result as Record<string, unknown> | undefined;
         const previous =
             (ctx.previous as Record<string, unknown> | undefined) ??
             ((ctx as unknown as { __previous?: Record<string, unknown> }).__previous ?? undefined);
 
-        const record: Record<string, unknown> =
-            after && typeof after === 'object'
-                ? after
+        const inputDoc =
+            input.data && typeof input.data === 'object'
+                ? input.data
                 : input.doc && typeof input.doc === 'object'
                   ? input.doc
-                  : previous && typeof previous === 'object'
-                    ? previous
-                    : {};
-
+                  : undefined;
+        const record: Record<string, unknown> =
+            after && typeof after === 'object'
+                ? // #1872 — overlay the after-row on the input doc so fields the
+                  // driver did not echo back (notably `multiple: true` lookups,
+                  // stored as an array column) stay visible to the flow's start
+                  // condition and `{record.<field>}` interpolation. The after-row
+                  // wins for every field it DOES return (id, DB-computed values).
+                  { ...(inputDoc ?? {}), ...after }
+                : inputDoc ?? (previous && typeof previous === 'object' ? previous : {});
+
+        // eslint-disable-next-line no-console
+        console.log('[dbg-bc] ctx.input=', JSON.stringify(ctx.input), 'after=', JSON.stringify(after), 'record=', JSON.stringify(record));
         const session = (ctx.session ?? {}) as { userId?: string };
 
         return {