refactor(plugin-security): move the authorization middleware out of security-plugin.ts

The one statement of start() that registers the authorization
middleware on the ObjectQL engine moves unedited to
security-plugin-authz-middleware.ts as registerAuthzMiddleware. It closed
over start()'s ctx, ql and metadata and nothing else, so it takes them as
parameters; start() keeps the statement's position, the comment above it
and the log line after it, and calls it from one block that hands it a
host literal of exactly the members it reads. The two module-level
declarations only the handler reads move with it: WriteImageCheckSeam,
which gains export so that security-plugin.ts can import it back
type-only for a docblock link, and userFacingDenialMessage. Import names
only the moved code reads leave security-plugin.ts, each whole import
with the comment lines that describe it.

The two readers that key on the moved read are re-pointed: the
system-context page's rows 1, 2 and 30 anchor the new function, and the
census ledger row that declares collapsesOntoRead for the owner_id guard
names it too. Move-only: no verdict changes.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017BoLT8Gaa8t9a7AWVH8qZa

Author: claude

content/docs/permissions/system-context.mdx

@@ -96,9 +96,9 @@ that silently does not happen.
 
 | # | Behaviour when `isSystem` | Package | What you get / what you lose | Anchor |
 |:--|:---|:---|:---|:---|
-| 1 | **The whole security middleware short-circuits** before any gate runs | plugin-security | Get: every CRUD/FLS/tenant/owner gate below skipped in one branch. Lose: every gate under it in this lane at once, down to and including the write-bypass row that widens the effective write scope to `org` (row 7) — this is the single largest behaviour on the page | `packages/plugins/plugin-security/src/security-plugin.ts#start` |
+| 1 | **The whole security middleware short-circuits** before any gate runs | plugin-security | Get: every CRUD/FLS/tenant/owner gate below skipped in one branch. Lose: every gate under it in this lane at once, down to and including the write-bypass row that widens the effective write scope to `org` (row 7) — this is the single largest behaviour on the page | `packages/plugins/plugin-security/src/security-plugin-authz-middleware.ts#registerAuthzMiddleware` |
 | 1b | **A flow run's system context is REFUSED governed writes to the identity-assignment objects** — the one check ahead of the middleware's short-circuit | plugin-security | Get: nothing — an insert, update, delete, transfer, restore or purge of `sys_user_position`, `sys_user_permission_set`, `sys_invitation` or `sys_member` from a context carrying `isSystem` and a `flowRunId` (a `runAs: 'system'` flow's data nodes, at any depth of their writes) is refused `PERMISSION_DENIED` before the short-circuit skips the ADR-0090 D12 gate and the identity write guard. Lose: nothing a platform writer held — a system context without a `flowRunId` (the seeders, better-auth and its reconciliation, invitation placement) passes on to the short-circuit unchanged, reads are not judged, and a `runAs: 'user'` run carries no `isSystem`, so the D12 gate judges it as the user it acts for | `packages/plugins/plugin-security/src/flow-system-identity-write-refusal.ts#assertFlowSystemIdentityWriteAllowed` |
-| 2 | **`owner_id` is not auto-stamped on INSERT** (the step 3.5 anchor guard is inside the block row 1 skips) | plugin-security | Lose: the row lands `owner_id = NULL`, so the default `owner_only_writes` policy hides it **from its own creator**. Get: nothing — this is a gap, not a capability | the step 3.5 guard block and the short-circuit that skips it are both inside `packages/plugins/plugin-security/src/security-plugin.ts#start` |
+| 2 | **`owner_id` is not auto-stamped on INSERT** (the step 3.5 anchor guard is inside the block row 1 skips) | plugin-security | Lose: the row lands `owner_id = NULL`, so the default `owner_only_writes` policy hides it **from its own creator**. Get: nothing — this is a gap, not a capability | the step 3.5 guard block and the short-circuit that skips it are both inside `packages/plugins/plugin-security/src/security-plugin-authz-middleware.ts#registerAuthzMiddleware` |
 | 3 | Row-level read filter resolves to "no filter" | plugin-security | Get: unscoped reads. Lose: row-level scoping entirely | `packages/plugins/plugin-security/src/security-plugin-read-filter.ts#getReadFilter` |
 | 4 | Field-level security returns **all** fields | plugin-security | Get: every column readable (`getReadableFields`) and writable (`getWritableFields`). Lose: field masking | `packages/plugins/plugin-security/src/security-plugin-field-readers.ts#resolveProjectionFieldMask` |
 | 5 | Export permission granted unconditionally | plugin-security | Get: `canExport` is `true` | `packages/plugins/plugin-security/src/security-plugin-object-admission.ts#canExport` |
@@ -141,7 +141,7 @@ that silently does not happen.
 | 29 | Reference-cleanup log attributes the write to `'system'` | objectql | Get: an honest actor label instead of `anonymous` when the context carries neither `userId` nor `actor` | `packages/objectql/src/engine.ts#recordReferenceCheckElevation` |
 | 29b | A traversing validation rule's related read skips the **caller's bounds** | objectql | Get: no row bound from the caller's own read on a related object no organization wall scopes, no read door on a header the rule reads through a `master_detail` field, and a related read even with no organization under a walled posture (a `tenantId` on the context still scopes it). Every caller that is not system is held to all three: a header its read door does not return is unavailable to the rule exactly as a header that exists nowhere is, whatever it holds, and a header it can read is judged on its stored values. A plain `lookup` to an object an organization wall scopes asks no read door, system caller or not | `packages/objectql/src/engine.ts#resolveOneHopRelated` |
 | 29c | A detail write's master-detail header read asks **no read door** | objectql | Get: the write binds the header a parent-scoped `requiredWhen` / `readonlyWhen` reads as `parent` from the header's stored row whoever can read it, as before. Every caller that is not system meets its own read door first: a header that read does not return answers as a header that exists nowhere — an unbound `parent`, and `reference_not_found` on the reference check (which a system caller's write skips altogether) | `packages/objectql/src/engine.ts#masterDetailHeadersCallerReads` |
-| 30 | **Bulk data event `organizationId` OMITTED** — the batch is published "not asserted" | plugin-security | Get: nothing — the `data.records.*` event still publishes. Lose: the per-organization attribution: this exit is taken before the security middleware composes any tenant wall, so it records no Layer 0 verdict on the operation (`OperationContext.tenantLayer0Verdict`, #15813), and the engine's bulk producer — which reads that recorded verdict and nothing else — omits the key rather than filling it from the caller's `tenantId`; a tenant-scoped consumer then does not deliver the event inside an organization wall (#15225) | `packages/plugins/plugin-security/src/security-plugin.ts#start` |
+| 30 | **Bulk data event `organizationId` OMITTED** — the batch is published "not asserted" | plugin-security | Get: nothing — the `data.records.*` event still publishes. Lose: the per-organization attribution: this exit is taken before the security middleware composes any tenant wall, so it records no Layer 0 verdict on the operation (`OperationContext.tenantLayer0Verdict`, #15813), and the engine's bulk producer — which reads that recorded verdict and nothing else — omits the key rather than filling it from the caller's `tenantId`; a tenant-scoped consumer then does not deliver the event inside an organization wall (#15225) | `packages/plugins/plugin-security/src/security-plugin-authz-middleware.ts#registerAuthzMiddleware` |
 | 30b | **The import doors admit a control opt-out** — `runAutomations: false` and `treatAsHistorical: true` on `POST /data/:object/import` and `/import/jobs` | rest | Get: an import whose rows are written with `skipAutomations` (no metadata-bound hook, no record-change trigger: an app's approvals and record freezes among them) or with `skipStateMachine` and `preserveAudit`. Every other caller, every signed-in user and administrator included, is refused `403 PERMISSION_DENIED` before the body is parsed, so nothing is written and no job is created. Inbound HTTP never carries the flag, so this is an in-process caller's door. Note: the flag still suppresses none of those controls by itself (see below); it only admits the opt-outs that do | `packages/rest/src/import-prepare.ts#importControlOptOutRefusal` |
 | 30c | **The import undo keeps the control skips** — `POST /data/import/jobs/:jobId/undo` | rest | Get: an undo whose deletes and restores are written with `skipAutomations` and `skipStateMachine`, so no metadata-bound hook, record-change trigger or `state_machine` rule refuses a reversal. Every other caller, every signed-in user and administrator included, undoes under those controls: a reversal one of them refuses is reported per row in the undo answer's `failures` and kept in the job's undo log, and the job is stamped reverted only once every row is. A historical job's `preserveAudit` belongs to the job, not the caller, and rides every undo. Inbound HTTP never carries the flag, so this is an in-process caller's door | `packages/rest/src/data-action-routes.ts#importUndoWriteContext` |