Order the records the way the system is learned

Jochen asked whether the order made sense. It did not -- it followed when
things happened to be decided, which after consolidation is fictional anyway
since record 5 alone folds decisions taken across a week.

Concretely wrong before: the domain statement sat at 8, after five engineering
rules; the constitution was scattered across 5, 12 and 17; the tiers landed at
15, 16, 21 and 22 with process records in between.

Now it walks: what the mesh is (1-3), its tiers from the bottom up (4-8), what
runs on them and how it gets there (9-10), how it is built (11-16), how it is
checked (17-18), how we work (19-23).

Two things made this safe rather than free. It is a permutation, not a
compaction, so the renames go through temporary names -- otherwise two files
want one slot and one is lost. And the reference rewrite is a single
simultaneous pass, because almost every number moved into a slot another number
was vacating; replacing one at a time would have cascaded and pointed things at
the wrong record while still resolving.

Verified: 284 [ADR NNNN](path) links across the repository, all with matching
text and target.

The ordering principle is now stated in 19 rather than left implicit -- the
repository already said "the numbering is the flow" about its folders, and
there was no reason for the records to be the exception.

02-DECISIONS/0020-the-mesh-is-governed-by-a-constitution.md

@@ -0,0 +1,63 @@
+---
+status: accepted
+date: 2026-07-10
+deciders: jochen
+reconstructed: true
+---
+
+# 20. The mesh is governed by a constitution, injected where work is decided
+
+> Reconstructed after the fact from the evidence cited below.
+
+## Context
+
+By mid-2026 the mesh was doing a large share of its own design and implementation work through
+agents. The rules those agents were expected to follow existed — in operating instructions, in
+convention documents, in the knowledge base — but they were **retrieved**: an agent had to know
+a rule existed in order to look it up.
+
+Rules that must be looked up are followed by whoever already knows them, which is precisely the
+population that does not need them. The rules being violated were the ones nobody thought to
+search for.
+
+## Considered options
+
+1. **Documentation plus review.** Rejected — it is what existed. Review catches a violation
+   after the work is done, and only if the reviewer knows the rule.
+2. **Lint and automated checks only.** Rejected as insufficient, not wrong. A check catches
+   what can be expressed mechanically; most of these rules are about judgement — what belongs
+   in a repository, when a criterion counts as verified.
+3. **A canonical rule set, injected into context wherever work is decided, with a check phase
+   before output is accepted.** Chosen.
+
+## Decision
+
+A single canonical document states the mesh's non-negotiable rules. It is **injected
+proactively** into every eligible design and analysis session — agents do not fetch it, it
+arrives — and a check phase verifies the session's output against it before the work proceeds.
+
+It is a governed document, not a page. Changing it requires a proposal, sign-off by reviewers
+who are not the proposer, and a recorded decision. Drive-by edits are reverted.
+
+Scoped override pages may **tighten** it for a team or product. They may never relax it.
+
+## Consequences
+
+- A rule reaches the work whether or not anyone remembered it existed.
+- The check phase makes a violation a blocking outcome rather than a review comment.
+- Two copies of the same rules now exist: this document, and the reasoning in HQ that earned
+  them. The enforced copy wins by default, so the reasoned copy quietly stops being true —
+  which is why [`00-META/how-we-build.md`](../00-META/how-we-build.md) is now the source
+  and the governed page is derived from it, via playbook
+  [`05-constitution-sync.md`](../00-META/process/05-constitution-sync.md).
+- Injection costs context on every eligible turn, and grows with the document. Nothing
+  currently bounds that.
+- The amendment process requires two reviewers, which a mesh with one human operator satisfies
+  only by counting agents. That tension is real and unresolved.
+
+## References
+
+- The governed page was authored 2026-07-10 and carries its own amendment process.
+- `feat(noxflow): HAL architectural conformance gate for reviewer + architect` (#296),
+  2026-06-10 — the check phase, predating the document it checks against.
+- Knowledge base: `platform/constitution`.