stack: Control-Plane-Sprache universell - Achse ist das Publikum, kein Instanz-Schalter (#103)

Files changed:
- AGENTS.md
- CHANGES.md
- VERSION
- docs/language-boundaries.md
- kb/CONVENTIONS.md
- kb/CONVENTIONS.md.template
- tools/chemenu/commands/dist_cmd.py

docs/language-boundaries.md

@@ -0,0 +1,126 @@
+# Language Boundaries
+
+Two languages run through this repo at once. `kb/` is written in whatever language the instance
+chose - German here, and the value lives in `kb/CONVENTIONS.md`'s `language:`. Everything that
+tells an agent what to do - [AGENTS.md](../AGENTS.md), every `CONTRACT.md`, everything under
+`instructions/` - is written in English, in every instance, whatever the first value says.
+
+The rule itself is in [AGENTS.md § File naming](../AGENTS.md#file-naming). This page holds the
+part that is not a rule: why the line runs where it does, why the English half is not a setting,
+and which argument for it turned out to be wrong.
+
+<!-- wikitool:toc -->
+## Contents
+
+- [The axis is the reader, not the owner](#the-axis-is-the-reader-not-the-owner)
+- [Why the control plane's language is English](#why-the-control-planes-language-is-english)
+- [Why it is not a parameter](#why-it-is-not-a-parameter)
+- [What the KB language still decides](#what-the-kb-language-still-decides)
+- [Where the line runs inside one file](#where-the-line-runs-inside-one-file)
+- [What would put this back on the table](#what-would-put-this-back-on-the-table)
+<!-- /wikitool:toc -->
+
+## The axis is the reader, not the owner
+
+For a long time the two halves could be told apart by asking who owned the file, and the answer
+came out right every time: the stack owns `AGENTS.md` and the contracts, which are English; the
+instance owns its pages and the templates that shape them, which are in the KB language. The
+ownership boundary is a real and load-bearing thing - [ownership-and-templates.md](ownership-and-templates.md)
+is about what it buys - so it was easy to read the language split as one of its consequences.
+
+It is not. The case that separates them is a page type an instance adds for itself. `types/`
+takes a new type without a code change, so an instance can write one; that file is instance-owned
+from the first line to the last, ships nowhere, and is nobody's to overwrite. Its authoring
+guidance is still instruction addressed to an agent, and reads exactly like the guidance in the
+four types the stack ships. Ownership says "yours"; the audience has not moved at all.
+
+So the question a line answers is not *whose file is this* but *who reads this line*, which is
+the same cut [kb/CONTRACT.md](../kb/CONTRACT.md#language-and-identifiers) already makes inside a
+single page between prose and identifiers - applied one level up, to the halves of a document.
+Ownership decides who may change a sentence. The reader decides what language it is in. The two
+questions were answered together for as long as they happened to agree.
+
+## Why the control plane's language is English
+
+Not because English is better for the purpose, and not to be neutral: this instance's operator
+reads German, and the pages are German for that reason.
+
+- **The control plane is almost entirely about identifiers, and the identifiers are English.**
+  `base_dir`, `provenance: sourced`, `--confirm`, exit 42, `root: kb`. A sentence in another
+  language explaining when to set `page_ref_fields` is already half English by the time it
+  reaches the verb, and the prose/identifier boundary inside it becomes something a reader has to
+  work out line by line.
+- **It quotes a body of material that is English and stays English.** The harness documentation
+  it has to agree with, the vendored skill-authoring sources under `commonplace/`, the tool's own
+  `--help`. A contract that translates their vocabulary makes its own claims harder to check
+  against them, not easier.
+- **One language keeps instances comparable.** Two instances running the same stack version hold
+  the same control plane byte for byte, so a question about one is answerable from the other -
+  and anything an instance changes locally shows up as a difference in content rather than in
+  language.
+
+## Why it is not a parameter
+
+The natural next move, once `kb/CONVENTIONS.md` holds `language:`, is a second value beside it -
+`control_plane_language:` - defaulting to English and settable by an instance that would rather
+read its contracts in its own language. That option is deliberately not taken.
+
+- **The knob's cost is paid by every file; its benefit lands on the few a human reads.** Every
+  rule about writing an instruction would have to name which of the two languages it means, every
+  example would need a note saying which one it is in, and every review of an instruction would
+  start by establishing which language it should have been in. The stack has one mechanism for
+  that class of problem - one rule, one place (AGENTS.md invariant 8) - and a second language
+  value forks it everywhere at once.
+- **The document the knob is for is read by an agent.** An instruction, a contract, a type-spec's
+  guidance half: the reader is a model, and a model reads the English fine. What the *operator*
+  reads is unaffected by any of this - see the section below.
+- **Today's local document is tomorrow's upstream candidate.** An instruction an instance wrote
+  for itself is the most likely thing it ever contributes back. Written in the KB language it
+  would have to be translated first, and the translation would have to re-derive the
+  prose/identifier boundary that the original author had in their head and did not write down.
+- **Nothing would check it.** There is no mechanical test for what language a paragraph is in -
+  a stop-word scan flags the quoted vocabulary the rule deliberately keeps and misses a cleanly
+  translated paragraph. A setting nothing enforces produces drift that is visible only to whoever
+  next opens the file.
+
+## What the KB language still decides
+
+Making the control plane English does not make the instance's language an implementation detail.
+`kb/CONVENTIONS.md`'s `language:` decides two things, and both are the ones an operator actually
+experiences:
+
+- **Page text.** Every page under `kb/`, and inside the page type-specs exactly the parts that
+  become page text - each one's `## Template` block and its `layout:` titles.
+- **What an agent says.** An agent speaks the KB language, whatever the file it just read was
+  written in. An instruction that models a sentence for the operator writes that model in
+  English, like the rest of the control plane, and the agent delivers it in the instance's
+  language.
+
+So an operator who reads no English gets German pages and German answers from an agent reading
+English instructions. The English is what the machinery is written in, not what it says back.
+
+## Where the line runs inside one file
+
+One file shape carries both halves, and it is worth knowing which is which before editing it: a
+page type-spec (`types/entity.md` and its three siblings). Its authoring guidance addresses an
+agent; its `## Template` block and `layout:` titles become the literal headings of pages; its
+field names and enum values are identifiers and are translated in neither direction.
+[types/type-spec.md § Who owns a type-spec](../types/type-spec.md#who-owns-a-type-spec) has that
+split as a table, and [ownership-and-templates.md](ownership-and-templates.md) § "Where the file
+boundary strains" has what it costs to keep two audiences in one file.
+
+## What would put this back on the table
+
+A `docs/` page goes stale when the reasoning stops holding rather than when the code changes, so
+it is worth naming what that would look like here. Two things would:
+
+- **A human starts reading the control plane directly and routinely** - not an operator checking
+  a rule now and then, which is the case today, but a workflow where people rather than agents
+  are the primary readers of `instructions/`. The second argument above is the one that fails
+  first, and it is the load-bearing one.
+- **The identifiers stop being English.** If the tool's own vocabulary were ever localized, the
+  first argument would invert: the prose would then be the only English left in a file that is
+  otherwise not, which is the situation this page argues against.
+
+Neither is close. Both are cheaper to notice here than to rediscover in an argument about a
+single file.