the-custodian/canon/architecture/adr-008-multi-tenancy-model.md

---
id: ADR-008
type: architecture-decision-record
title: "Multi-Tenancy Framework: Four Planes, Graduated Levels, Declared Posture"
status: proposed
decided_by: Bernd Worsch
date: "2026-08-17"
revision: "draft-2"
tags: ["architecture", "multi-tenancy", "isolation", "placement", "maturity", "tenant-engine", "flex-auth", "rapp-postgres", "scaling"]
---

# ADR-008: Multi-Tenancy Framework — Four Planes, Graduated Levels, Declared Posture

## Status

**Proposed, draft-2.** Draft-1 (2026-08-17) proposed a single model with fixed
characteristics. It was rejected on the grounds that the estate does not need
one model of multi-tenancy — it needs a framework able to describe, hold, and
improve several situations at once, including repos that do not separate
tenants rigorously today and must be developed toward doing so. Draft-2 is
that reframe.

This document decides things currently owned by `tenant-engine`, `flex-auth`,
`rapp-postgres`, `adaptive-pricing`, and `railiance-platform`. It must be
reviewed by those owners before ratification; §18 lists what each is being
asked to accept.

## 1. Context

The estate has been building multi-tenancy for months and has never written
down what it is building. Five documents each cover a slice:

| Document | Covers | Status |
|---|---|---|
| `iam-profile_v0.3` (NetKingdom) | Tenant identifier shape, `tenant_roles` claim, staleness rules | Ratified |
| `tenant-engine-boundary-contract_v0.1` (NetKingdom) | Who owns tenant records, roles, plan assignment | Ratified |
| `business-app-service-contract_v0.1` §1 (Custodian) | Business apps: instance-per-client, tenant-keyed data | Ratified |
| `rapp-postgres/docs/adr/ADR-0001` | Consumer + tenant isolation in PostgreSQL | Proposed, governs one repo |
| `rapp-postgres/docs/canon-drafts/shared-platform-relational-storage_v0.1` | The stacked-boundary gap | Routed 2026-08-10, **still unratified** |

Four failures follow.

**The gap has been diagnosed once and the fix stalled.** The
shared-platform-relational-storage draft was written to fill this hole. It has
sat unratified for a week and appears in neither canon directory. §19 attaches
a ratification path so this one does not join it.

**Placement is owned by nobody.** `user-engine-pg` and `target-revenue-pg` are
dedicated; `apps-pg`, `net-kingdom-pg`, `platform-pg`, `state-hub-db` and
`forgejo-db` are shared. Both patterns are live, neither is written down, and
each new service copies whichever neighbour it consulted. `tenant-engine`
raised this with `railiance-platform` on 2026-08-16; unanswered.

**Two contradictory tenancy defaults are already ratified.**
`business-app-service-contract` §1.2 makes instance-per-client the default for
business apps. Platform services pool all tenants into one database. Nothing
states which shape a new service takes, and no definition distinguishes the
two categories.

**There is no honest way to describe a repo that is not there yet.** This is
the failure draft-1 missed. The estate absorbs and will keep absorbing repos
with weak or absent tenant separation — app-local accounts, no tenant column,
ad-hoc filtering. Today such a repo is simply non-conformant, which gives it
two bad options: misrepresent its posture, or stay outside the framework
entirely. Both are worse than a framework that can say "this repo is at level
1, its target is level 3, here is the gap and the evidence."

## 2. What this document is

**A framework, not a model.** It does not specify one correct multi-tenancy
implementation with a fixed set of characteristics. It supplies:

- **Terminology** — four planes, and graduated levels within each (§3, §4).
- **A declaration** — the posture vector, so any repo can state where it
  actually is (§5).
- **A conformance rule** — accuracy, not altitude (§6).
- **Methodology** — analyze, establish, improve, guard (§12).
- **Evidence definitions** — what proves a claimed level (§13).

A service is conformant when its declared posture is accurate and its
trajectory is recorded. A service is non-conformant when it claims a level it
cannot evidence — regardless of how high or low that level is.

## 3. Four orthogonal planes

"Is this multi-tenant?" is treated as one question. It is four, and they are
independent:

| Plane | Question | Vocabulary owner |
|---|---|---|
| **Identity (I)** | How is a tenant named and validated? | `tenant-engine` / IAM Profile |
| **Authorization (A)** | How is a request bound to the tenants it may act for? | `flex-auth` |
| **Enforcement (E)** | Where, mechanically, is the tenant boundary enforced? | This framework |
| **Placement (P)** | Which physical substrate holds a tenant's data? | `railiance-platform` |

Treating them as one produces concrete errors today. `rapp-postgres`'s
`PostgresConsumer` carries a field `tenantIsolation: consumer-service-boundary`
— an **E**-plane fact recorded in a **P**-plane artifact, reading as though the
storage platform enforces something it does not. The "dedicated versus shared"
argument routinely mixes P (capacity, blast radius) with E (correctness).

The planes are separated **precisely so that each may sit at a different
level**. A repo can be strong on identity and weak on enforcement, or the
reverse, and the framework must state that without flattening it to a single
verdict. That is the whole point, and draft-1 lost it by collapsing E into a
single fixed rule.

**Decision 3.1:** every document, declaration, and plan tier that says
"isolation" MUST name which plane it means.

**Decision 3.2:** the planes couple at their top levels — `E4` is only
reachable at `P3` or above — and that coupling MUST be stated where it applies
rather than used to argue the planes are one.

## 4. Graduated levels

Each plane carries an ordered ladder. Higher is stronger, not better: the
right level is the one a service can evidence and its risk warrants.

### 4.1 Identity (I) — how the tenant is named

| Level | State |
|---|---|
| **I0** | No tenant concept. Data is not attributable to a tenant. |
| **I1** | A local tenant notion exists but does not conform to `tenant:<grouping>:<name>`. |
| **I2** | Canonical identifiers used, validated against the ratified vocabulary; `tenant-engine` is the source of existence. |
| **I3** | I2 plus capability roles (`PLTF`/`IAM`/`VEN`/`CUS`) honoured, with live `tenant-engine` re-query for privileged, destructive, credential-vending or `aal2`-class decisions rather than trusting the cached `tenant_roles` claim. |

Note `business-app-service-contract` §2.1 sets app-local accounts as the v1
baseline for business apps — an explicitly sanctioned low level with recorded
triggers for moving up. That is the pattern this framework generalises.

### 4.2 Authorization (A) — how a request is bound to a tenant

| Level | State |
|---|---|
| **A0** | No authorization, or tenant context not carried on the request. |
| **A1** | Ad-hoc checks scattered through handlers. |
| **A2** | A single local authorization boundary; tenant context bound once, centrally. |
| **A3** | Decisions delegated to `flex-auth` as PDP, with live re-query where the IAM Profile requires it. |

### 4.3 Enforcement (E) — where the tenant boundary actually holds

This is the reframed core. Draft-1 asserted one rule for everyone; this is a
ladder whose top is platform-enforced.

| Level | Mechanism | Bypassed by |
|---|---|---|
| **E0** | None. Data not tenant-keyed; separation is incidental or absent. | Anything. |
| **E1** | Data tenant-keyed, filtering applied per query at call sites. | One missing predicate. |
| **E2** | Filtering centralised at a single service-side choke point that binds authenticated identity to permitted tenants. | Code that bypasses the choke point. |
| **E3** | Platform-assisted: row-level security keyed on a session GUC set at pool checkout, or an equivalent data-access layer the application cannot trivially route around. | A `SECURITY DEFINER` function, a missing policy, or a wrong GUC. |
| **E4** | Structural: the connection a workload holds cannot address another tenant's data at all. Requires per-tenant credentials and per-tenant substrate. | Only a platform-level compromise. |

Three properties of this ladder matter.

**E3 is real and is not forbidden.** Draft-1 rejected RLS on the grounds that
a control depending on the consumer setting a session variable "looks like a
database guarantee without being one". The observation is correct; the
conclusion was wrong. E3 is materially stronger than E2 — it converts "every
call site must remember" into "one checkout path must be right" — and it is
the standard mitigation in pool-model systems. What was actually wrong was
*calling E3 by E4's name*. The honesty requirement survives; the prohibition
does not.

**Higher enforcement is the direction of travel, not an optional extra.**
Services holding data whose cross-tenant exposure would be a reportable breach
SHOULD target E3 or above. The framework's default expectation for a new
platform service is **E2 at first serve, E3 recorded as target**.

**Platform enforcement is a platform obligation, not only a consumer one.**
Draft-1 placed the whole burden on consumers permanently. It is now stated
that reaching E3 requires the storage platform to *offer* the mechanism —
provisioned RLS policies, a documented GUC contract, and a probe.
`rapp-postgres` ADR-0001 §4 already commits to provisioning it on request;
that offer becomes an obligation with a defined contract (§18.6). Where a
consumer wants E3 and the platform has not supplied the mechanism, the gap is
the platform's, not the consumer's.

### 4.4 Placement (P) — which substrate holds the data

Draft-1's `R0` ("shared tables, tenant column") is removed: that was an
E-plane state mislabelled as placement. Corrected ladder:

| Level | Shape | Live occupants |
|---|---|---|
| **P0** | Shares a database with another consumer (schema or tables co-resident). | None sanctioned; the state absorbed repos often arrive in. |
| **P1** | Database per consumer, shared cluster. | `audit-core`, `tenant-engine` on `platform-pg` |
| **P2** | Dedicated cluster per consumer. | `user-engine-pg`, `target-revenue-pg` |
| **P3** | Dedicated cluster per tenant. | Business apps per `business-app-service-contract` §1.2 |
| **P4** | P3 plus separate region or jurisdiction. | None |

**P0 → P1 → P2 does not raise the E level.** Those steps buy consumer
isolation, capacity predictability, independent backup retention, and a
smaller operational blast radius. They leave the tenant boundary exactly where
the E level puts it. Only P3 makes E4 reachable. This is the single most
misusable fact in the framework and §11 governs how it may be described
commercially.

**Decision 4.5:** P1 is the default for platform services; P3 is the default
for client-facing business apps, as already ratified. A service unsure which
it is must resolve that before choosing (§18.4).

## 5. The posture vector

A service states its tenancy posture as one level per plane, plus a target and
a date:

```yaml
tenancy:
  current:  { I: 2, A: 3, E: 2, P: 1 }
  target:   { I: 2, A: 3, E: 3, P: 1 }
  reviewed: "2026-08-17"
  gap:
    E: "Choke point exists and is tested; RLS not yet provisioned. Blocked on
        rapp-postgres offering the GUC contract. Target Q4."
```

Worked examples, as best assessed today and subject to owner correction:

| Service | Current | Notes |
|---|---|---|
| `tenant-engine` | `I2 A3 E2 P1` | Moving to P1 under TEN-WP-0009; E2 via its own service boundary. |
| `audit-core` | `I2 A3 E2 P1` | Same shape; holds audit data, so E3 is the more urgent target. |
| A newly absorbed repo | `I1 A1 E1 P0` | Conformant **if declared**, with a recorded path. |

The vector is what makes the framework hold both situations honestly. A repo
at `I1 A1 E1 P0` is not a failure — it is a described state with a direction.
A repo claiming `E3` with no RLS policy is a failure regardless of how good the
rest of it is.

**Decision 5.1:** the posture vector is declared in the repo, not in the hub,
consistent with local-files-are-source-of-truth.

## 6. Honest absorption — conformance is accuracy, not altitude

The governing rule of this framework:

> **A service is conformant when its declared posture is accurate, its target
> is recorded, and it does not claim a level it cannot evidence. It is
> non-conformant when it overclaims — at any altitude.**

Consequences, stated deliberately:

- Declaring `E0` is conformant. Concealing `E0` is not.
- A repo may be absorbed at any posture. It may not be absorbed silently.
- No service is blocked from the estate for being low on a ladder. Services
  MAY be blocked from *specific work* — serving a tenant grouping, holding a
  data class, carrying a plan tier — by requirements expressed as minimum
  levels (§11).
- Downgrading is permitted and must be declared. A regression discovered by
  guarding (§12) is a defect; a regression declared in advance is a decision.

This is what the plane separation is *for*. Without it, "not rigorous about
tenant separation" is a single verdict that a repo either passes or fails.
With it, the same repo is `I1 A1 E1 P0` with a path — which is a plan, not an
indictment.

## 7. Portability across placement levels

Movement between P levels must be an operational change, not a rebuild.
Adopted from `tenant-engine`'s TEN-WP-0009 design:

- Connect by injected credential only — no cluster, host, namespace, or
  database name in source.
- Own a whole database, never tables inside someone else's. Sharing a cluster
  is reversible; sharing a database makes relocation a schema merge.
- Idempotent schema creation.
- No cross-database joins or co-location assumptions.

A service meeting these moves P1 → P2 by: create target, dump, restore, swap
the credential reference, restart.

**Decision 7.1:** mandatory at P1 and above. At P3, SHOULD rather than MUST —
the consolidation `business-app-service-contract` §1.3 preserves is a real
benefit, but a per-client instance that never moves is not misconformant for
naming its own database.

## 8. Placement triggers

A level change decided under pressure is decided badly. Each service records
at provisioning time what would move it:

- Noisy neighbour on a latency-critical path
- A compliance or residency requirement
- A plan tier requiring a higher minimum (§11)
- Backup retention or RTO no longer fitting
- Connection or memory ceiling reached (§16)

**Decision 8.1:** triggers MUST be *monitored*, not merely recorded. A trigger
in a YAML comment that nobody re-reads is documentation, not control. The
`platform-pg` ceiling in §16 is the first that requires an actual alert.

**Decision 8.2:** placement policy ownership is proposed to
`railiance-platform`. This framework supplies the ladder, the triggers, and
the declaration; it does not appoint per-workload placement. See §18.2 — this
remains their call and their open request.

## 9. Credentials as a tenancy control

Short-lived leased credentials from OpenBao, re-read at connection checkout,
with overlap-first rotation, bound the residual risk at every E level below
E4: a leaked credential expires rather than persisting. This is stronger than
the industry norm of a long-lived per-service secret and belongs in the
tenancy model, not only in credential-management canon.

**Decision 9.1:** static long-lived database credentials are not a sanctioned
path for any service above E0.

## 10. Blast radius must be published

**Decision 10.1:** every platform holding consumer data MUST publish, in
concrete terms, what a leaked runtime credential can and cannot reach at the
levels it operates. `rapp-postgres` ADR-0001 §5 is the reference
implementation. Where the model cannot provide a guarantee, the platform says
so and names the escalation, rather than describing a weaker control in
stronger language.

## 11. Commercial expression — room to be successful

Isolation will be sold. The framework must let commercial and presentation
work rather than obstruct them, while preventing a claim that cannot be
evidenced.

**Decision 11.1:** plan tiers are expressed internally as **minimum levels**,
not as implementation labels. A tier may require `E3 P2`; it need not print
that string anywhere customer-facing.

**Decision 11.2:** marketing and product language is free. There is no
requirement to expose level labels, ladder names, or this document to
customers. "Dedicated infrastructure", "isolated tenancy", "private instance"
all remain available.

**Decision 11.3:** the constraint is on **evidence, not vocabulary**. Any
customer-facing isolation or availability claim must map to a minimum level
the delivering service actually holds, recorded once when the tier is defined.
The review is internal and happens at tier definition — not per campaign, per
page, or per conversation.

**Decision 11.4:** the one hard line — a claim that another tenant *cannot*
reach the customer's data requires **E4**. Everything softer than that
absolute has room. This is the claim that reaches compliance questionnaires
and contracts, and it is the one that must be true.

`adaptive-pricing` owns plan terms; `tenant-engine` owns which plan a tenant
holds. Neither currently maps a tier to minimum levels; §18.5 asks them to,
for tiers making isolation or availability claims only.

## 12. Methodology — analyze, establish, improve, guard

The framework is operated as a cycle, not consulted as a reference.

**Analyze.** Assess a repo against the four ladders and produce its current
vector. Output: the `tenancy.current` block with the reasoning recorded.
Applies to new services and absorbed ones alike.

**Establish.** Declare the target vector and the gap. The target is set by the
data class held, the tenant groupings served, and any plan tier carried — not
by ambition. Output: `tenancy.target` plus a recorded gap per plane.

**Improve.** Move one plane at a time. Cross-plane moves are where mistakes
happen — raising P while leaving E untouched is exactly the misstep §4.4
warns about. Each step is ordinary repo work with ordinary evidence.

**Guard.** Verify continuously that the declared posture still holds. Guarding
checks a service **against its own declaration**, not against a universal
maximum. This is what makes the verification problem tractable: nobody has to
prove every service is at E4; the check is that nobody is below what they
declared, and nobody claims what they cannot evidence.

Regression found by guarding is a defect; regression declared in advance is a
decision. The estate has been bitten twice by silent pin rollbacks that
produced ordinary-looking 403s and 404s rather than errors. Posture regression
will look the same, so guarding must be designed for invisible failure rather
than for crashes.

## 13. Evidence per level

Guarding requires each level to have a defined evidence artifact. Proposed:

| Level | Evidence |
|---|---|
| **I2** | Identifiers validated against the ratified vocabulary; rejection test for a malformed tenant id. |
| **I3** | Live re-query demonstrated on an `aal2`-class path; cached-claim path shown not to be used there. |
| **A2** | Single choke point identified; test that an unbound request is refused. |
| **A3** | Live decision against `flex-auth` with a denial observed at the endpoint, not only at the decision surface. |
| **E1** | Every tenant-owned table carries the tenant key. Schema-level check, mechanical. |
| **E2** | Choke point identified; adversarial test that an identity bound to tenant A cannot read tenant B. |
| **E3** | RLS policies present on every tenant-owned table; probe that a session without the GUC set reads nothing; probe that a wrong GUC reads nothing. |
| **E4** | Per-tenant credential demonstrated unable to connect to another tenant's substrate. |
| **P1–P4** | Provisioning declaration plus the platform's own isolation probes. |

**Decision 13.1:** a level is claimed only with its evidence artifact present.
This turns §6's accuracy rule from an honour system into a check.

**Decision 13.2:** the E2 and E3 evidence artifacts do not exist anywhere in
the estate today. `rapp-postgres` runs 15 adversarial probes, all against the
*consumer* boundary, none against the tenant boundary inside a consumer. This
is the framework's largest live gap and §18.3 seeks an owner.

## 14. Alternatives considered

**One fixed model with a single set of characteristics** (draft-1). *Rejected
by the operator:* it cannot describe a repo that is not there yet, forcing
absorbed repos either to misrepresent their posture or to stay outside the
framework. A framework that can only describe its own end state is not a
framework.

**A maturity model with a single overall level** (bronze/silver/gold).
*Rejected:* collapses the plane separation that makes the framework useful. A
service strong on identity and weak on enforcement has a specific, actionable
gap; one composite score hides it and invites averaging.

**Schema-per-consumer in one database** (sanctioning P0). *Rejected:*
`pg_catalog` is readable per-database, so every co-resident enumerates every
other's table and column names regardless of `GRANT`s. Retained in the ladder
as a describable state, never as a sanctioned target.

**Row-level security as the *consumer* boundary.** *Rejected:* puts a
correctness-critical boundary between two services inside query predicates.
Retained as E3 for the *tenant* boundary, where the realistic alternative is
application code rather than a database.

**Mandating E4 for everyone.** *Rejected:* the tenant grouping taxonomy
includes `consumer` (private individuals) and `family`. A cluster per private
individual is economically impossible; the taxonomy is itself evidence that
pooling is required.

**Leaving each repo to its own model.** *Rejected:* this is the status quo,
and it produced two contradictory ratified defaults plus an unowned placement
question.

## 15. Challenge against outside practice

**Where the framework is stronger than typical.** Most SaaS multi-tenancy
literature (AWS's silo/pool/bridge framing among them) models exactly one
boundary — tenant-to-tenant. This estate has **two stacked boundaries**:
platform-service-to-platform-service, and tenant-to-tenant inside a consumer.
Naming them separately and refusing to enforce both with one mechanism is
uncommon and correct.

Graduated per-plane levels are also stronger than the usual silo/pool/bridge
trichotomy, which describes deployment shape only. Silo/pool/bridge is
approximately this framework's P plane with the other three missing — which is
why it cannot express "pooled infrastructure, structurally enforced
boundary", or the reverse.

**Where it is weaker, and this is the finding that matters.** The pool model's
standard mitigation is a *verified* enforcement layer that every service is
demonstrably routed through. The estate has the concept (E2/E3) and none of
the verification (§13.2). A single missing `WHERE tenant_id = ?` in any
consumer is a cross-tenant breach that no platform control catches, no probe
fails, and no log shows as an error.

**Where the estate has quietly adopted a good pattern without naming it.**
Short-lived leased credentials re-read at checkout, with overlap-first
rotation, beat the industry norm of a long-lived per-service secret. §9
promotes it to a tenancy control.

**Cell-based architecture remains unexplored.** Neither P nor E describes a
cell — a fixed-size slice of infrastructure serving a bounded set of tenants,
sized so one cell's failure is survivable and cell count scales linearly.
Given the estate spans railiance, NetKingdom, HelixForge and Coulomb, cells
may fit better than per-tenant clusters at the point P1 runs out (§18.8).

## 16. Scaling demands

Measured against the live `platform-pg` specification, not estimated.

```
instances:        1              (no HA; single-node rail)
max_connections:  100
memory limit:     1Gi
per consumer:     14 connections (12 runtime + 2 migration)
```

**Connection ceiling: roughly six consumers.** Seven consumers request 98 of
100 before CNPG's instance manager, metrics exporter, and reserved slots. Two
are provisioned today. **We are at roughly a third of capacity and the third
request will not feel like a scaling event.**

**Memory likely binds first.** 100 backends against 1Gi is ~10MB per backend
for shared buffers, work_mem and overhead. Connection exhaustion errors
clearly; memory pressure OOM-kills and degrades every co-resident at once.

**Raising E is not free on a shared substrate.** RLS with a per-checkout GUC
does not itself increase connection count, but it forecloses aggressive
transaction-level pooling for consumers that adopt it. E3 on P1 interacts with
the ceiling above and should be planned against it.

**Restore time couples all consumers.** Physical backup is instance-wide, so a
consumer's RTO is a function of *total* instance size, not its own. One large
consumer silently degrades every co-resident's recovery promise.

**`instances: 1` means no P1 tenant has HA.** A tier promising uptime cannot
be satisfied at P1 as currently built — an availability floor belongs in §11's
minimum-level vocabulary alongside isolation.

## 17. Consequences

- The estate gains one vocabulary and, more importantly, a way to be honest
  about partial adoption.
- Absorbed repos get a described state and a path instead of a failing grade.
- `tenantIsolation` in `PostgresConsumer` is revealed as a mislabelled field
  (§18.1).
- The two ratified defaults are reconciled by scope, at the cost of needing a
  classification rule.
- The verification problem becomes tractable: guard against declaration, not
  against a universal maximum.
- Draft-1's prohibition on RLS is reversed; `rapp-postgres` acquires an
  obligation to define and offer the E3 mechanism.
- Nothing here changes a running system.

## 18. Open questions

1. **`tenantIsolation` field** — `rapp-postgres`: rename to name its plane and
   carry a level (`tenancy.E: 2`), or move it out of the storage declaration.
2. **Placement ownership** — `railiance-platform`: accept the ladder, the
   triggers, and the monitoring obligation in §8.1, and appoint a recorded
   placement owner per workload.
3. **E2/E3 evidence artifacts** — *owner needed.* Who builds the adversarial
   cross-tenant probes and the RLS conformance check? Both `audit-core` and
   `tenant-engine` have declined fleet-scope work on correct boundary
   reasoning, so this needs appointing. Highest-severity gap (§13.2).
4. **Business app vs platform service** — Custodian canon: a classification
   rule, so a new repo knows whether P3 or P1 is its default. Candidate: reuse
   `repo-classification-standard_v1.0` rather than invent a second taxonomy.
5. **Tier → minimum level mapping** — `adaptive-pricing` and `tenant-engine`:
   required only for tiers making isolation or availability claims (§11).
6. **E3 mechanism** — `rapp-postgres`: what exactly is the GUC contract, and
   is it provisioned per consumer on request or offered as a standard option?
7. **Engine neutrality** — the P ladder rests on a PostgreSQL property
   (per-database catalogs). State it engine-specifically and say so, or
   abstract it and risk a non-Postgres implementation that silently differs?
   Inherited unresolved from the v0.1 draft.
8. **Cell-based partitioning** — evaluate at consumer #4 rather than now?
   Neither P nor E describes a cell.

## 19. Ratification path

The predecessor draft stalled because it was routed without one.

1. Reviewed by `tenant-engine`, `flex-auth`, `rapp-postgres`,
   `railiance-platform`, and `adaptive-pricing` against §18.
2. Each of those repos publishes its own posture vector (§5) as part of
   review. **The framework is validated by whether it can describe them
   accurately** — if a repo cannot express itself in these four ladders, the
   ladders are wrong and this document changes, not the repo.
3. On acceptance, **supersedes** the routing of
   `rapp-postgres/docs/canon-drafts/shared-platform-relational-storage_v0.1-draft.md`,
   whose §§3–8 are absorbed here. That draft is then withdrawn rather than
   left pending.
4. On acceptance, `rapp-postgres/docs/adr/ADR-0001` moves to `accepted` and is
   annotated as the PostgreSQL implementation of the E and P ladders.