Security: Reports surface ignores caller identity — cross-user/cross-tenant IDOR (read/delete any report) + scheduled reports bypass owner RLS #2980

Surfaced by the ADR-0096 execution-surface audit (the #2849 bug-class sweep). Two related defects on the reports surface, same root: ReportService discards the caller's ExecutionContext and runs against sys_saved_report / the report's target object with SYSTEM_CTX ({ isSystem: true }), so RLS/FLS/ownership/tenant scoping are all bypassed. The REST route layer only calls enforceAuth (authentication), not ownership.

Finding 1 — IDOR: any authenticated user can read or delete any saved report

packages/plugins/plugin-reports/src/report-service.ts:

• getReport(reportId, _context) (:244) — _context unused; queries sys_saved_report by id with SYSTEM_CTX (:246).
• deleteReport(reportId, _context) (:251) — same; deletes by id + cascades schedules with SYSTEM_CTX (:255-260).
• listReports({ object, ownerId }) (:231) — ownerId is caller-supplied and optional; with it omitted, returns up to 500 reports across all owners with SYSTEM_CTX (:238-239).

The routes (packages/rest/src/rest-server.ts):

• GET /data/reports/:id (:5448) → svc.getReport(req.params.id, context)
• DELETE /data/reports/:id (:5472) → svc.deleteReport(req.params.id, context)
• GET /data/reports (:5400) → svc.listReports({ object, ownerId: q.ownerId }, context)

Each does enforceAuth(req, res, context) then hands the id/query to the service, which throws the context away. Impact: an authenticated low-privilege user reads or deletes any other user's saved report by id (cross-owner; cross-tenant in tenancy.mode='multi'), and enumerates all reports via the list endpoint.

Finding 2 — Scheduled reports run as system, exfiltrating the target object

report-service.ts dispatchDue() (:411-425) executes each due schedule via:

const report = await this.getReport(schedule.report_id, { isSystem: true });      // :413
const result = await this.executeReport({ ...report, format: fmt }, { isSystem: true }, false); // :425

executeReport threads its context into the target-object query (:299-306), so { isSystem: true } makes the scheduled run bypass the report owner's RLS/sharing and email out every row of the target object. The interactive path (:299, caller-scoped) is correct; the scheduled path is not. Unlike flows post-#1888, reports have no owner-scoped runAs — and there is no warning/lint here.

Suggested fix

• get/delete/listReports must run under the caller's context (respect _context), or enforce an explicit owner/tenant predicate against sys_saved_report. SYSTEM_CTX is legitimate only for server-controlled metadata stamps (last_run_at), not for authorization-bearing reads/deletes.
• dispatchDue must resolve the schedule/report owner (owner_id, already on the row) to a real ExecutionContext and run executeReport under it — the reports analogue of ADR-0073 runAs:'user'/owner-scoping — not { isSystem: true }.

Relationship to ADR-0096 / #2849

This is the TRUSTED-IMPLICIT class the ADR names (a surface that ignores the caller and rides system authority). It is not the #2849 empty-principal fall-open (it's an unconditional SYSTEM_CTX bypass), but it is exactly what the ADR-0096 D4 conformance matrix + D2 systemContext(reason) audit would have caught. Tracking under the ADR-0096 evidence base; fix independently of the mechanism.

Refs: ADR-0096 (PR #2975), #2849, ADR-0073 (runAs posture).