From 852b0b6b0b38f3feae83c52397b3ec572a8950aa Mon Sep 17 00:00:00 2001
From: "Jonathan D.A. Jewell" <6759885+hyperpolymath@users.noreply.github.com>
Date: Tue, 4 Aug 2026 23:32:03 +0100
Subject: [PATCH] policy: bun-first runtime order; name the ban's exemption
 classes
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The banned list already carried rescript, yet 71 repos across the estate
hold a rescript.json — the policy was declared and never enforced, and it
never said WHERE a banned language is legitimately allowed to live, so
there was nothing to enforce against.

- banned-exempt-repo-classes names the only three homes: <lang>-ecosystem,
  adapter, mcp. Anywhere else a banned language is a defect regardless of
  how it arrived. (rescript's homes: rescript-ecosystem, and the adapter
  in proven.)
- js-runtime-order makes bun the default. Deno was bought for its Rust
  implementation and paid for in compatibility tax; bun wins on the thing
  that actually decides, and Deno's longevity is not a safe bet to build
  a 400-repo estate on. Deno stays second for existing code, pnpm third,
  npm last resort.
- ruby joins the banned list alongside typescript, rescript, go, python.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 a2ml-templates/AGENTIC.a2ml.template | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/a2ml-templates/AGENTIC.a2ml.template b/a2ml-templates/AGENTIC.a2ml.template
index 71677ee5..182b19cd 100644
--- a/a2ml-templates/AGENTIC.a2ml.template
+++ b/a2ml-templates/AGENTIC.a2ml.template
@@ -60,7 +60,30 @@ documentation = "inline"
 languages = ["affinescript", "rust", "gleam", "{{PRIMARY_LANGUAGE}}"]
 
 # banned: Languages the agent must NEVER use, even if asked.
-banned = ["typescript", "rescript", "go", "python", "makefile"]
+banned = ["typescript", "rescript", "go", "python", "ruby", "makefile"]
+
+# banned-exempt-repo-classes: the ONLY places a banned language may appear.
+# A ban is about not letting a language spread through the estate — not about
+# pretending it does not exist. Interoperating with an ecosystem means writing
+# in it, in one bounded, named place:
+#   <lang>-ecosystem — the repo that exists to hold that language's world
+#                      (e.g. rescript-ecosystem)
+#   adapter          — a bounded translation layer to a foreign ecosystem
+#                      (e.g. the ReScript adapter in `proven`)
+#   mcp              — an MCP server for one specific external thing
+# Anywhere else, a banned language is a defect regardless of how it got there.
+banned-exempt-repo-classes = ["<lang>-ecosystem", "adapter", "mcp"]
+
+# js-runtime-order: preference for anything needing a JS runtime or package
+# manager. Take the first that can do the job; drop to the next only when it
+# genuinely cannot.
+#   bun  — the default. Compatibility decides, and bun has it.
+#   deno — second. Kept for existing code; not chosen for new work. Walking
+#          everything through Deno was a real cost, and its longevity is not
+#          a safe bet to build on.
+#   pnpm — third, when a real node_modules layout is unavoidable.
+#   npm  — last resort only.
+js-runtime-order = ["bun", "deno", "pnpm", "npm"]
 
 # ── Project-Specific Overrides ────────────────────────────────────────────
 [agentic-config.project-specific]