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

[os-zhuang]

Closes #1872.

Problem (confirmed via full-kernel repro)

A multiple: true lookup is stored as an array column (not a junction table — objectql has no junction logic; the expand path at engine.ts already treats the value as Array.isArray). A data driver may not echo that column back on create, so it was absent from the after-create record the record-change flow sees:

• record.target_channels != null evaluated false → the flow never ran;
• {piece.target_channels.0} interpolation resolved empty.

Root cause (two distinct gaps, both confirmed by instrumented repro)

1. The record-change trigger's buildContext read ctx.input.**doc**, but objectql lifecycle hooks carry the written row under ctx.input.**data** (insert/update). So the input fallback was always undefined — the flow only ever saw the driver's (incomplete) after-row.
2. Interpolation's path regex required identifier segments, so a numeric .0 segment ({rec.channels.0}) never matched the fast path.

Fix

• @objectstack/trigger-record-change — buildContext reads input.data and overlays the after-row on it ({ ...inputData, ...after }): the after-row wins for every field the driver returns (id, DB-computed), and fields it omits (multi-lookup arrays) come from the input. Affects only record-change flows.
• @objectstack/service-automation — {var.path.N} numeric segments now index into arrays (template.ts), so {record.channels.0} resolves.

Tests

• Full-kernel repro: a driver that deliberately doesn't echo the array column → a record-after-create flow gated on record.target_channels != null fires AND its update_record stamps {record.target_channels.0} (= ch_1). Fails on each gap before the fix; passes after.
• Array-index interpolation unit tests (single / embedded / out-of-range).
• @objectstack/service-automation 199 pass, @objectstack/trigger-record-change 20 pass (incl. the Record-change trigger plugin loads but flows never fire on data writes (7.4.1) #1491 integration test — confirms the input.data change doesn't regress the record path).

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Project	Deployment	Actions	Updated (UTC)
spec	Ready	Preview, Comment	Jun 15, 2026 2:33pm

[github-actions]

📓 Docs Drift Check

This PR changes 2 package(s): packages/services, packages/triggers.

5 hand-written doc(s) reference the affected code and may need an implementation-accuracy re-verification:

• content/docs/guides/packages.mdx (via packages/services)
• content/docs/guides/runtime-services/audit-service.mdx (via packages/services)
• content/docs/guides/runtime-services/index.mdx (via packages/services)
• content/docs/guides/runtime-services/settings-service.mdx (via packages/services)
• content/docs/protocol/objectos/i18n-standard.mdx (via packages/services)

Advisory only. To re-verify, run the docs-accuracy-audit workflow scoped to these files:
node scripts/docs-audit/affected-docs.mjs origin/main → pass the list as args.docs.