refactor(descriptiles): migrate .machine_readable/6a2 → descriptiles (naming canon) (#676)

## What

Estate naming mandate (2026-06-30): the machine-readable metadata family
is **`descriptiles`**; **`6a2` is fully deprecated** and must never be
reintroduced. `rsr-template-repo` already led this rename (PR #128).
This brings AffineScript into line.

## Changes (38 files, mechanical + verified)

- `git mv .machine_readable/6a2 .machine_readable/descriptiles` (6
`.a2ml` files)
- Updated the **one** code dependency: `tools/check-doc-truthing.sh`
`STATE_FILE` path
- Updated `.machine_readable/TRUST.contractile` deny-rule path
- Updated ~30 doc/metadata references (paths + `6a2 metadata`
family-name prose)

Replacement was **word-boundaried** (`\b6a2\b` → `descriptiles`) so
checksum substrings are untouched; `Cargo.lock` hash coincidences
(`…846a2afffd…`) were excluded.

## Verification (real toolchain)

Built off system OCaml 4.14.1 + opam (dune 3.24.0):
- `dune build` = **exit 0** (zero build impact — metadata/doc only)
- **zero `\b6a2\b` references remain** anywhere (excl. Cargo.lock
checksums)
- `check-doc-truthing.sh` reads the renamed
`.machine_readable/descriptiles/STATE.a2ml` correctly

## Pre-existing red gates (NOT caused by this PR)

README fails two back-link gates **on `main` independently** of this
change (README is untouched here — verified against pristine
`origin/main`):
1. README → `SOUNDNESS.adoc` (soundness-ledger gate) — fixed by **#675**
2. README → `CAPABILITY-MATRIX.adoc` (doc-truthing gate) — third README
defect, being fixed alongside #675

Once those README fixes land, this PR's CI clears.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

.claude/CLAUDE.md

@@ -29,12 +29,12 @@ https://github.com/hyperpolymath/nextgen-languages/blob/main/docs/disambiguation
 
 The following files in `.machine_readable/` contain structured project metadata:
 
-- `.machine_readable/6a2/STATE.a2ml` - Current project state and progress
-- `.machine_readable/6a2/META.a2ml` - Architecture decisions and development practices
-- `.machine_readable/6a2/ECOSYSTEM.a2ml` - Position in the ecosystem and related projects
-- `.machine_readable/6a2/AGENTIC.a2ml` - AI agent interaction patterns
-- `.machine_readable/6a2/NEUROSYM.a2ml` - Neurosymbolic integration config
-- `.machine_readable/6a2/PLAYBOOK.a2ml` - Operational runbook
+- `.machine_readable/descriptiles/STATE.a2ml` - Current project state and progress
+- `.machine_readable/descriptiles/META.a2ml` - Architecture decisions and development practices
+- `.machine_readable/descriptiles/ECOSYSTEM.a2ml` - Position in the ecosystem and related projects
+- `.machine_readable/descriptiles/AGENTIC.a2ml` - AI agent interaction patterns
+- `.machine_readable/descriptiles/NEUROSYM.a2ml` - Neurosymbolic integration config
+- `.machine_readable/descriptiles/PLAYBOOK.a2ml` - Operational runbook
 
 ---
 
@@ -57,7 +57,7 @@ The following files in `.machine_readable/` contain structured project metadata:
 | **Bash/POSIX Shell** | Scripts, automation | Keep minimal |
 | **Python** | SaltStack only | No other Python permitted |
 | **Nickel** | Configuration language | For complex configs |
-| **A2ML** | State/meta files | .machine_readable/6a2/STATE.a2ml, .machine_readable/6a2/META.a2ml, .machine_readable/6a2/ECOSYSTEM.a2ml |
+| **A2ML** | State/meta files | .machine_readable/descriptiles/STATE.a2ml, .machine_readable/descriptiles/META.a2ml, .machine_readable/descriptiles/ECOSYSTEM.a2ml |
 | **Julia** | Batch scripts, data processing | Per RSR |
 | **OCaml** | AffineScript compiler | Language-specific (compiler-host tooling lives here) |
 | **Ada** | Safety-critical systems | Where required |

.machine_readable/TRUST.contractile

@@ -26,7 +26,7 @@
     (deny "push without confirmation in the same session")
     (deny "add a language feature not in ANCHOR.a2ml thesis")
     (deny "reverse any ADR (ADR-001 through ADR-010) without a new ADR")
-    (deny "delete or overwrite the 6a2/ core files (STATE/META/ECOSYSTEM/AGENTIC/NEUROSYM/PLAYBOOK)")
+    (deny "delete or overwrite the descriptiles/ core files (STATE/META/ECOSYSTEM/AGENTIC/NEUROSYM/PLAYBOOK)")
     (deny "modify IDApTIK without explicit instruction (AGPL — separate repo, separate session)")
   )
 

.machine_readable/anchors/ANCHOR.a2ml

@@ -61,7 +61,7 @@ thesis:
 
 authorities:
   scope-statement:
-    - ".machine_readable/6a2/META.a2ml (ADRs)"
+    - ".machine_readable/descriptiles/META.a2ml (ADRs)"
     - "~/Desktop/Frontier_Programming_Practices_AffineScript/AI.a2ml (v2.0)"
 
   human-guide:

.machine_readable/6a2/AGENTIC.a2ml …chine_readable/descriptiles/AGENTIC.a2ml.machine_readable/6a2/AGENTIC.a2ml renamed to .machine_readable/descriptiles/AGENTIC.a2ml .machine_readable/6a2/AGENTIC.a2ml renamed to .machine_readable/descriptiles/AGENTIC.a2ml

@@ -483,10 +483,10 @@ consequences = """
   form across format passes.
 """
 references = [
-  ".machine_readable/6a2/STATE.a2ml [track-a-manhattan]",
-  ".machine_readable/6a2/STATE.a2ml [[open-bug]] BUG-001",
-  ".machine_readable/6a2/STATE.a2ml [[open-bug]] BUG-002",
-  ".machine_readable/6a2/META.a2ml [[adr]] ADR-002 (scaled Let rule)",
+  ".machine_readable/descriptiles/STATE.a2ml [track-a-manhattan]",
+  ".machine_readable/descriptiles/STATE.a2ml [[open-bug]] BUG-001",
+  ".machine_readable/descriptiles/STATE.a2ml [[open-bug]] BUG-002",
+  ".machine_readable/descriptiles/META.a2ml [[adr]] ADR-002 (scaled Let rule)",
   "lib/ast.ml ExprLet (lines 105-111), StmtLet (lines 170-176)",
   "lib/lexer.ml (ZERO/ONE never emitted)",
   "lib/parser.mly quantity rule (lines 180-183)",

.machine_readable/6a2/ECOSYSTEM.a2ml …ine_readable/descriptiles/ECOSYSTEM.a2ml.machine_readable/6a2/ECOSYSTEM.a2ml renamed to .machine_readable/descriptiles/ECOSYSTEM.a2ml .machine_readable/6a2/ECOSYSTEM.a2ml renamed to .machine_readable/descriptiles/ECOSYSTEM.a2ml

@@ -4,7 +4,7 @@
 
 Project metadata and AI agent configuration files live under `.machine_readable/`. All metadata files use the `.a2ml` extension; the `.scm` extension is reserved for Guix (`guix.scm`, `.guix-channel`).
 
-## Core 6a2 metadata (`.machine_readable/6a2/`)
+## Core descriptiles metadata (`.machine_readable/descriptiles/`)
 
 - **STATE.a2ml** - Current project state, progress, blockers, next actions, session notes
 - **ECOSYSTEM.a2ml** - Position in ecosystem, relationships to sibling projects
@@ -29,7 +29,7 @@ Project metadata and AI agent configuration files live under `.machine_readable/
 
 ## Workflow
 
-1. Read `.machine_readable/6a2/*.a2ml` files at session start
+1. Read `.machine_readable/descriptiles/*.a2ml` files at session start
 2. Check `STATE.a2ml` for current phase, blockers, next actions
 3. Follow patterns and constraints from `AGENTIC.a2ml`
 4. Follow methodology gates from `agent_instructions/methodology.a2ml`