fix(security): enforce referenced-object RLS/FLS on $expand (#2850)

[os-zhuang]

Fixes #2850.

Problem

ObjectQL.expandRelatedRecords (packages/objectql/src/engine.ts) resolved lookup / master_detail / user references by calling the driver directly (driver.find), never re-entering the security middleware for the referenced object. Only tenantId was threaded, so the referenced object's RLS, FLS, and CRUD gate were skipped — cross-tenant was the only surviving boundary. The middleware's post-pass FLS masking covers only the top-level object; field-masker does not recurse into expanded records.

Impact: any API-key/session caller who could read a base row could ?expand=<fk> and receive the full referenced record — including rows the referenced object's owner-only RLS would hide and fields FLS would mask. Reachable via GET /data/:object/:id?expand=… and POST /data/:object/query (both funnel through engine.find/findOne).

Fix

Route the expand batch through the engine's own this.find for the referenced object instead of the raw driver, so the security middleware applies that object's RLS + FLS to the collected id $in [...] batch. This re-enters the middleware once per level (no N+1) and preserves the existing batched load and depth guard (nested expand still recurses manually, so MAX_EXPAND_DEPTH is unaffected).

The sub-read is tagged with a server-set __expandRead context marker (executionContext is server-built, never client-supplied — consistent with the existing internal __readScope/__writeScope markers). The security middleware uses it to implement the surgical policy agreed on the issue:

• PUBLIC referenced object → waive only the object-level CRUD / requiredPermissions gate (the row is already broadly readable via the '*' wildcard grant, so applying that gate to an expansion would over-block common status/owner lookups without adding protection). RLS injection + FLS masking still run.
• PRIVATE referenced object → keep the full gate (RLS + FLS + CRUD). Expansion may reveal only rows the caller could have read directly; a private object the caller can't read gracefully retains the bare FK id.

No per-field escape hatch is introduced (option A on the issue).

Changes

• packages/objectql/src/engine.ts — expandRelatedRecords resolves via this.find(referenceObject, …, { context: { __expandRead: true } }).
• packages/plugins/plugin-security/src/security-plugin.ts — compute expandSkipCrud (find + __expandRead + public), and AND it into the requiredPermissions (step 1.5) and CRUD (step 2) gates only.

Tests

• engine.test.ts — new: the expand sub-read routes through the middleware for the referenced object tagged __expandRead; three existing expand assertions updated to reflect the secured path (the referenced driver.find now carries the query options/context instead of undefined).
• security-plugin.test.ts — new: __expandRead waives the CRUD gate for a public referenced object, does not waive it for a private one, and still injects RLS on the expand sub-read.

All @objectstack/objectql (853) and @objectstack/plugin-security (172) tests pass; both packages typecheck; the real-$expand rest/export-integration test passes.

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Project	Deployment	Actions	Updated (UTC)
spec	Canceled		Jul 15, 2026 1:28pm

[github-actions]

📓 Docs Drift Check

This PR changes 2 package(s): @objectstack/objectql, @objectstack/plugin-security.

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

• content/docs/concepts/metadata-lifecycle.mdx (via @objectstack/objectql)
• content/docs/data-modeling/formulas.mdx (via packages/objectql)
• content/docs/deployment/migration-from-objectql.mdx (via @objectstack/objectql)
• content/docs/deployment/vercel.mdx (via @objectstack/objectql)
• content/docs/getting-started/cli.mdx (via @objectstack/plugin-security)
• content/docs/kernel/services-checklist.mdx (via @objectstack/objectql)
• content/docs/kernel/services.mdx (via @objectstack/objectql)
• content/docs/permissions/access-recipes.mdx (via packages/plugins/plugin-security)
• content/docs/permissions/authentication.mdx (via @objectstack/objectql)
• content/docs/permissions/authorization.mdx (via packages/plugins/plugin-security)
• content/docs/permissions/explain.mdx (via @objectstack/plugin-security)
• content/docs/permissions/permissions-matrix.mdx (via packages/plugins/plugin-security)
• content/docs/permissions/sharing-rules.mdx (via @objectstack/plugin-security)
• content/docs/plugins/index.mdx (via @objectstack/objectql, @objectstack/plugin-security)
• content/docs/plugins/packages.mdx (via @objectstack/objectql, @objectstack/plugin-security)
• content/docs/protocol/objectos/index.mdx (via @objectstack/objectql)
• content/docs/protocol/objectql/state-machine.mdx (via @objectstack/objectql)
• content/docs/releases/implementation-status.mdx (via @objectstack/objectql, @objectstack/plugin-security)
• content/docs/releases/v9.mdx (via @objectstack/objectql)
• content/docs/ui/audience-based-interfaces.mdx (via packages/plugins/plugin-security)
• content/docs/ui/dashboards.mdx (via @objectstack/plugin-security)

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.