Commentary: the posture/maturity boundary is recomputability (KG-IN-0003)

gate-house asked kings-guard to check the posture/maturity boundary,
with the concern that a second grading authority would be the same shape
of mistake as a second decision point. Its proposed line was volatile
current state against slow progression.

Answered with a proposed revision, KG-DEC-2026-002, argued in
docs/PostureMaturityBoundary.md (KG-COM-0001).

Volatility is an observation about data, not a definition. It fails at
both edges and, more importantly, describes the two things without
partitioning them — every case left to argument is a route by which a
second grading authority arrives.

The discriminator is already in the statute. §9.5 requires maturity to
return the same level from the same criteria and evidence and calls that
determinism the thing that makes it an Engine; §3.3 makes inference Staff
by construction. So: recompute against the same criteria and evidence —
must get the same answer, it is maturity and belongs in an engine; cannot
promise the same answer, it is posture and belongs in Staff.

It is one rule read from both sides. §9.5 already says a criterion that
cannot be evaluated by rule is not yet a criterion; the mirror is that a
judgment that can be evaluated by rule is not posture but a criterion in
the wrong repository.

kings-guard accepts the constraint this puts on its own side: capability
readiness is not an input to posture, since feeding a deterministic value
into a non-deterministic one would blur the boundary from our door. That
also answers the incident-dependency half of the intake.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UEtvmYUBP2fDtirJGWn5MW

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 4014379@bnt-lap001
Assistant-Session: 4af9e20f-1768-4afc-951b-b507784e382b

decisions/decisions.md

@@ -151,3 +151,81 @@ advisory and fixture-driven, which is the honest state and not a workaround.
 - kings-guard's assent removes one of the two adaptations §11 lists as
   outstanding. The standard remains proposed pending `flex-auth` and
   `ops-warden`.
+
+## KG-DEC-2026-002 — The posture/maturity boundary is recomputability, not volatility
+
+```yaml
+id: KG-DEC-2026-002
+kind: decision
+title: The posture/maturity boundary is recomputability, not volatility
+status: resolved
+owner: Bernd Worsch
+repo: kings-guard
+standard: net-kingdom/canon/standards/security-layer-model_v0.7.md
+origin_ref: KG-IN-0003
+commentary: docs/PostureMaturityBoundary.md
+affects:
+- kings-guard
+- gate-house
+- maturity-engine
+- net-kingdom
+created: '2026-08-29'
+updated: '2026-08-29'
+decided_by: Bernd Worsch
+disposition: revision-proposed
+```
+
+## Context
+
+`gate-house` asked `kings-guard` (`KG-IN-0003`) to check a boundary it had not
+drawn: posture and maturity are both graded, and two engines grading the same
+subject would be the same shape of mistake as a second decision point. Its
+proposed line was posture as volatile current state about an actor against
+maturity as slow progression of a capability.
+
+## Decision
+
+**Revision proposed.** The line is nearly right and drawn on the wrong axis.
+Volatility is an observation about data, not a definition, and it fails at both
+edges — evidence can land in a burst, and a healthy subject can hold one posture
+for months. More importantly it describes the two things without partitioning
+them, and every case it leaves to argument is a route by which a second grading
+authority arrives.
+
+The discriminator is already in the statute. §9.5 requires maturity to return
+the same level from the same criteria and evidence, and says that determinism is
+what makes it an Engine rather than an opinion; §3.3 says a repository whose
+core function is inference is Staff by construction. So:
+
+> Given the same criteria and the same evidence, recompute. If you must get the
+> same answer, it is maturity and belongs in an engine. If you cannot promise
+> the same answer, it is posture and belongs in Staff.
+
+This is one rule read from both sides. §9.5 already states the maturity half —
+a criterion that cannot be evaluated by rule is not yet a criterion. The posture
+half is its mirror: a judgment that can be evaluated by rule is not posture, it
+is a criterion in the wrong repository. Together they partition; "volatile
+versus slow" does not.
+
+Full argument: `docs/PostureMaturityBoundary.md` (KG-COM-0001).
+
+## Consequences accepted by kings-guard
+
+- **Capability readiness is not an input to posture.** Readiness is
+  deterministic and posture is not; feeding one into the other would make
+  posture partly recomputable and blur the boundary from our side. Accepted as a
+  constraint on this repository.
+- Consequently, tracking our gaps in `maturity-engine` creates no incident-path
+  dependency: we never consult our own readiness to judge an observation, so
+  `maturity-engine` being unreachable mid-incident changes nothing about posture
+  evaluation. This answers the second half of `KG-IN-0003`.
+- Anything we currently call posture that proves recomputable belongs in
+  `maturity-engine` as a criterion, and we will hand it over rather than keep it.
+
+## Limit
+
+The test says "the same evidence", which is not yet well defined estate-wide.
+Until §17's schemas exist, two parties can disagree about whether they hold the
+same evidence and recomputability is a thought experiment rather than a check.
+§17 is therefore load-bearing for this decision; `kings-guard` owns the
+emission-cadence half under `KG-WP-0003-T02`.

docs/PostureMaturityBoundary.md

@@ -0,0 +1,142 @@
+---
+title: "Commentary — the posture/maturity boundary"
+document_id: KG-COM-0001
+version: 1.0.0
+status: Published
+date: 2026-08-29
+repo: kings-guard
+kind: commentary
+commentary_on: net-kingdom/canon/standards/security-layer-model_v0.7.md
+sections: ["8", "9.5", "3.3"]
+answers: KG-IN-0003
+classification: Public
+---
+
+# Commentary — the posture/maturity boundary
+
+A commentary, not a proposed edit. `gate-house` owns the rules (statute §2);
+this is `kings-guard`'s reading of a boundary it asked us to check, offered in
+the form the conformance loop expects. Adopt, revise, or reject.
+
+## The question
+
+`KG-IN-0003` asks us to check a line `gate-house` had not drawn:
+
+> posture is volatile current security state about an actor, published by
+> kings-guard and rendered by access-engine, while maturity is slow progression
+> of a capability against declared criteria
+
+with the concern stated plainly: *a second grading authority would be the same
+shape of mistake as a second decision point.*
+
+That concern is correct and it is the reason the line has to be exact.
+
+## The line is nearly right and drawn on the wrong axis
+
+Volatility is the wrong discriminator. Rate of change is an observation about
+the data, not a definition of it, and it fails at both edges: a maturity
+criterion can move quickly when evidence lands in a burst, and a posture can sit
+unchanged for months on a subject that stays healthy. A boundary that has to
+hold under §6 cannot rest on how fast a value happens to move, because nothing
+prevents the value from moving at a different speed tomorrow.
+
+Worse, "volatile versus slow" describes the two things without partitioning
+them. Every case it does not obviously cover is an argument, and arguments at a
+boundary are how a second grading authority arrives — gradually, and each time
+for a good local reason.
+
+## The line the statute already draws
+
+The discriminator is in §9.5 and does not need to be invented:
+
+> Given the same criteria and the same evidence it MUST return the same level;
+> that determinism is what makes it an Engine rather than an opinion.
+
+And in §3.3, generally:
+
+> A repository whose core function is inference or judgment fails this test by
+> construction and is Staff, however much of its work happens at runtime.
+
+So the test is **recomputability**:
+
+> Given the same criteria and the same evidence, recompute. If you must get the
+> same answer, it is **maturity** and it belongs in an engine. If you cannot
+> promise the same answer, it is **posture** and it belongs in Staff.
+
+This is the statute's own organizing principle — determinism — applied to the
+one boundary where it had not yet been used. It is not a new rule. It is the
+existing rule read at a place it had not been pointed.
+
+## It is one rule read from opposite sides
+
+§9.5 already states the maturity half: *a criterion that cannot be evaluated by
+rule is not yet a criterion.* That is maturity refusing to absorb inference.
+
+The posture half is its mirror, and stating it completes the pair: **a judgment
+that can be evaluated by rule is not posture — it is a criterion sitting in the
+wrong repository.**
+
+Together they partition rather than describe. There is no case the pair leaves
+to argument, which is exactly what "volatile versus slow" cannot offer.
+
+## Three consequences
+
+**1. The migration direction is defined, permanently.** Anything currently
+called posture that turns out to be recomputable should move to
+`maturity-engine` as a criterion. Anything in `maturity-engine` that needs
+judgment is not yet a criterion and moves back to Staff. The boundary maintains
+itself under change instead of needing to be re-adjudicated, because the test is
+mechanical and applies to each item rather than to the category.
+
+**2. The second-grading-authority failure is structurally prevented, not
+conventionally avoided.** `gate-house`'s worry is answered by the shape of the
+test rather than by both parties agreeing to stay on their own side. Two
+authorities cannot grade the same subject on this line, because a single subject
+property is either recomputable or it is not, and that fact is not a matter of
+which repository claims it.
+
+**3. Capability readiness must not be an input to posture.** This is the
+constraint the test imposes on *us*, and we accept it. Readiness is
+deterministic; posture is not. If readiness fed posture, posture would become
+partly recomputable and the boundary would blur from the kings-guard side — the
+same failure, arriving through the door we own.
+
+This also answers the second half of `KG-IN-0003`. Tracking our gaps in
+`maturity-engine` creates no dependency we would rather not carry during an
+incident, because we never consult our own readiness to judge an observation. If
+`maturity-engine` is unreachable mid-incident, nothing about posture evaluation
+changes. The dependency would only exist if we had already made the mistake this
+consequence forbids.
+
+## A caution about the word
+
+`posture` has the drift profile that `control plane` had: it sounds specific,
+and it quietly absorbs whatever sits next to it. That is how this repository
+came to describe itself as a control plane in the first place, and §8 exists
+because the estate has been bitten by exactly this.
+
+The recomputability test is a defence against that drift, because it is
+mechanical and can be applied to a candidate before the word is stretched to
+cover it. We would rather be held to it than trusted about it.
+
+## What this commentary does not claim
+
+- It does not touch §8's three-way split. `kings-guard` publishes posture,
+  `gate-house` defines its authority meaning, `access-engine` renders it. That
+  division is unaffected and we are not asking to widen our half.
+- It does not make posture an engine concept. Posture stays non-deterministic
+  and stays Staff. The test explains *why*, which is what was missing.
+- It proposes no §4 catalog change.
+
+## An honest limit
+
+The test says "the same evidence", and that phrase is not yet well defined
+anywhere in the estate. Until §17's request-claim and gap-record schemas exist,
+two parties can disagree about whether they hold the same evidence, and
+recomputability is a thought experiment rather than a check.
+
+That is a real limit and it is not an argument against the line — a boundary
+that is correct but not yet mechanically checkable is still better than one that
+is checkable and wrong. It does mean §17 is load-bearing for this commentary,
+and `kings-guard` has the emission-cadence half of that work under
+`KG-WP-0003-T02`.

intakes/intakes.md

@@ -77,9 +77,11 @@ id: KG-IN-0003
 kind: intake
 title: 'Review requested: security layer model v0.3 (maturity-engine, and the posture/maturity
   boundary)'
-status: open
+status: closed
 origin: cross-repo
 origin_ref: net-kingdom security-layer-model_v0.3
+outcome: promoted
+promoted_to: KG-DEC-2026-002
 priority: medium
 owner: kings-guard
 requested_by: gate-house
@@ -103,5 +105,15 @@ description: 'v0.3 is proposed and changes sections 4, 9 and 13 only; the v0.2 a
   Assent, revision, or rejection acceptable.'
 created: '2026-08-28T20:40:12.260389Z'
 updated: '2026-08-28T20:40:12.260389Z'
+closed: '2026-08-29'
+resolution: 'Answered with a proposed revision. The boundary is recomputability,
+  not volatility: given the same criteria and the same evidence, if you must get
+  the same answer it is maturity and belongs in an engine, and if you cannot
+  promise the same answer it is posture and belongs in Staff. Drawn from statute
+  section 9.5 and section 3.3 rather than imposed on them, and it partitions
+  where volatile-versus-slow only describes. kings-guard accepts the constraint
+  this puts on its own side: capability readiness is not an input to posture,
+  which also answers the incident-dependency question. Commentary:
+  docs/PostureMaturityBoundary.md. Decision: KG-DEC-2026-002.'
 state_hub_intake_id: "01a04d8d-66f8-70ef-b2b5-1eff03569471"
 ```