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`.