docs(policy): retiring a flake means its references too (#566)

§2.1 already rules Nix retired and rightly warns against mass-deletion.
The owner ruling of 2026-07-28 — *"nix flakes are deprecated and to be
thrown from the estate"* — is **reconciled with that warning rather than
overriding it**: removal stays a per-repo judgement made while you are
*already working in the repo*. Opportunistic, never a fan-out sweep.

## What was genuinely missing

**Deleting `flake.nix` does not retire Nix.** Measured on
`trope-checker`
([#47](hyperpolymath/trope-checker#47)), one
flake had **ten satellites**:

| file | what it kept alive |
|---|---|
| `.envrc` | a direnv `use flake` block |
| `Justfile` + `contractiles/Justfile` | a `nix-shell` recipe |
| `build/setup.sh` | `nix` in package-manager detection **and** the
install switch |
| `install-tools.sh` | a flake-detecting branch running **ahead of
Guix** |
| `.github/dependabot.yml` | a `nix` `package-ecosystem` entry |
| `.gitignore` / `.gitattributes` | `flake.lock` and `*.nix` rules |
| `compliance/reuse/dep5` | `flake.lock` in the lockfile glob |
| docs / `PLAYBOOK.a2ml` | prose |

Leave any behind and the toolchain still reaches for Nix. They're now
listed in §2.1.

## Two traps recorded, because both cost time

- **`dependabot.yml` rejects the whole file on one malformed entry** —
re-parse after removing the `nix` ecosystem.
- **A root `.githooks/` is usually load-bearing** (CI runs validators
straight from it) — allowlist it in `root-allow.txt`; don't "tidy" it
away in passing.

Plus the standing caveat, restated where it will be read: a repo whose
`guix.scm` is a scaffold stub has **no working packaging** once the
flake is gone. Make Guix real, or fill the sealed container, *in the
same change*.

## Flagged, not resolved — the canon disagrees with itself

This repo carries **two** `LANGUAGE-POLICY.adoc` files and they
contradict each other:

- **`./LANGUAGE-POLICY.adoc`** (this one) self-declares canonical, is
the more current — §2.2 records the squisher-corpus identity clobber
measured 2026-07-29 across 418 repos — and makes **Bun tier 1**.
- **`./rhodium-standard-repositories/spec/LANGUAGE-POLICY.adoc`** still
lists **Deno** as *"Replaces Node/npm/Bun"*.

PR #51 on trope-checker cites the first; the estate `CLAUDE.md` I was
working under states the second. **I have not resolved this** — it needs
an owner decision on which file is authoritative. Note the Nix hardening
was also added to the *other* file earlier (standards #557), so both now
carry it; the runtime-tier contradiction is untouched.

Renders clean under `asciidoctor`.

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

Author: hyperpolymath

LANGUAGE-POLICY.adoc

@@ -77,6 +77,35 @@ WARNING: Do *not* mass-delete `flake.nix`. Campaign #102 hand-diffed 277
 candidates and removed exactly *one*. Fan-out REMOVE verdicts have a measured
 ~100% over-call rate here. Removal is a per-repo judgement, not a sweep.
 
+HARDENED 2026-07-28 (owner ruling): Nix flakes are to be *thrown out* of the
+estate, not merely tolerated where they linger. Reconcile that with the warning
+above as follows: removal remains a **per-repo judgement made while you are
+already working in that repo** — opportunistic, never a fan-out sweep.
+
+When you do retire a flake, remove the *references* as well as the file.
+Measured on `trope-checker` (PR #47), one `flake.nix` had ten satellites, and
+leaving any of them behind keeps Nix alive in the toolchain:
+
+* `.envrc` — a direnv `use flake` block
+* `Justfile` (and `.machine_readable/contractiles/Justfile`) — a `nix-shell` recipe
+* `build/setup.sh` — `nix` in package-manager detection and the install switch
+* `install-tools.sh` — a `flake.nix`-detecting branch, often ahead of Guix
+* `.github/dependabot.yml` — a `nix` `package-ecosystem` entry
+* `.gitignore` / `.gitattributes` — `flake.lock` and `*.nix` rules
+* `compliance/reuse/dep5` — `flake.lock` in the lockfile glob
+* docs and `PLAYBOOK.a2ml` prose
+
+CAUTION: `dependabot.yml` rejects the *whole file* on one malformed entry —
+re-parse it after removing the `nix` ecosystem. And do not "tidy" a root
+`.githooks/` away while you are there: it is usually load-bearing (CI runs
+validators directly from it); allowlist it in `root-allow.txt` instead.
+
+Retiring the mirror does not finish the job. A repo whose `guix.scm` is a
+scaffold stub — empty `inputs`, `TODO` markers, or a `{{PROJECT_NAME}}`
+placeholder — has *no working packaging* once the flake is gone. Make the Guix
+side real, or fill the sealed container, *in the same change*. Do not allowlist
+the flake instead.
+
 === 2.2 Identity and licence in `guix.scm`
 
 A `guix.scm` must name *its own project*. Measured 2026-07-29 across 418 repos: