instructions: the agent speaks the KB language in chat - AGENTS.md § Conversation language, and instructions sync compiles the language tag into every published SKILL.md (#116); 10.0.0-beta.9

Files changed:
- AGENTS.md
- CHANGES.md
- VERSION
- docs/explanation/language-boundaries.md
- docs/reference/commands/types-instructions-and-docs.md
- instructions/CONTRACT.md
- instructions/dev/stack-build/SKILL.md
- instructions/dev/stack-close/SKILL.md
- instructions/dev/stack-dev/SKILL.md
- kb/CONVENTIONS.md
- kb/CONVENTIONS.md.template
- tools/CONTRACT.md
- tools/chemenu/commands/doctor.py
- tools/chemenu/commands/instructions_cmd.py
- tools/chemenu/tests/test_doctor.py
- tools/chemenu/tests/test_instructions_cmd.py

Co-Authored-By: Claude Code <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

docs/explanation/language-boundaries.md

@@ -7,7 +7,9 @@ tells an agent what to do - [AGENTS.md](../../AGENTS.md), every `CONTRACT.md`, e
 is the stack's own documentation for humans, for a different reason (§ "The stack's human
 documentation").
 
-The rule itself is in [AGENTS.md § File naming](../../AGENTS.md#file-naming). This page holds the
+The rules themselves are in [AGENTS.md § File naming](../../AGENTS.md#file-naming) (the language
+of a file) and [AGENTS.md § Conversation language](../../AGENTS.md#conversation-language) (the
+language of what an agent says). 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.
 
@@ -18,6 +20,7 @@ and which argument for it turned out to be wrong.
 - [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)
+  - [Why a rule alone did not hold](#why-a-rule-alone-did-not-hold)
 - [Where the line runs around a page type](#where-the-line-runs-around-a-page-type)
 - [The stack's human documentation](#the-stacks-human-documentation)
 - [What would put this back on the table](#what-would-put-this-back-on-the-table)
@@ -105,6 +108,31 @@ So an operator who reads no English gets German pages and German answers from an
 English instructions. The English is what the machinery is written in, not what it says back -
 with one exception, the stack's documentation for humans (§ "The stack's human documentation").
 
+### Why a rule alone did not hold
+
+For a while the conversation rule was a sentence about files' languages in `AGENTS.md`, and an
+instance on German pages still saw an agent that wrote its pages in German and everything else in
+English: progress notes between tool calls, the closing report. Pages were right because the
+step that writes a page reads `kb/CONVENTIONS.md` first; the chat was wrong because nothing had
+put the value in front of the agent by then. Three things stacked up:
+
+- **The rule sat in the wrong section.** A paragraph about the language of files does not read as
+  a rule about speaking, and it was phrased as a statement of fact rather than an instruction.
+  It now has a section of its own.
+- **The value was one hop away.** `AGENTS.md` ships verbatim to every instance and so cannot
+  carry the instance's language; it names the file that does. A short ingest has written several
+  English messages before it opens that file.
+- **The context is English.** Instructions, tool output and error text all are, and one short
+  message from the operator is outweighed by them - the more so for a weaker model.
+
+So the value is also compiled into the published copy of each skill, as a one-line block under
+its frontmatter that `wikitool instructions sync` writes: the language tag and a pointer to the
+rule, nothing else. The rule stays in `AGENTS.md` and the value in `kb/CONVENTIONS.md`; the block
+holds neither as text of its own, only puts the one in front of the task that needs it. It is a
+tag, not a language name, because a table of names would be the compiler's opinion about
+languages, which `conventions.py` deliberately has none of. A session with no skill is covered by
+the `AGENTS.md` section alone.
+
 ## Where the line runs around a page type
 
 A page type's contract is where the two languages meet most closely, and it is worth knowing