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

instructions/CONTRACT.md

@@ -160,7 +160,19 @@ Both targets are generated and gitignored. A fresh clone therefore has no skills
 
 Copies, not symlinks: a symlink cannot go stale but is unreliable on Windows checkouts and
 does not survive being archived or copied. The price of a copy is drift, and drift is what
-`tools/wikitool instructions verify` checks - byte for byte against the source.
+`tools/wikitool instructions verify` checks - against what `sync` would write from the source,
+which is the source byte for byte plus one generated line.
+
+That line is the instance's conversation language. When `kb/CONVENTIONS.md` declares a
+`language:`, `sync` writes `> **Conversation language: \`de\`** - see \`AGENTS.md\` §
+Conversation language ...` as the first paragraph under each published `SKILL.md`'s frontmatter,
+so the value is in context when the task starts, not a file read away (the rule is
+[AGENTS.md § Conversation language](../AGENTS.md#conversation-language); the line carries the
+value and a pointer to it, not a second copy of the rule). Only `SKILL.md` gets it, in both
+target directories, and its frontmatter and every other file of the skill stay byte-identical. With no
+language declared the copy is the source unchanged. A skill's source never contains the line, and
+changing `language:` makes `verify` and `doctor` report the copies as drifted, naming the line as
+the reason; re-running `sync` repairs it.
 
 ## Writing an instruction
 
@@ -191,12 +203,13 @@ Scaffold with `tools/wikitool new instruction --name "<name>"`; the contract is
   `instructions/migrations/` belong to the release they shipped with and are not rewritten. The
   stack's own instructions are held to this by a test in the origin repository; what an instance
   writes for itself is its own decision.
-- **Write it in English, and let the agent speak the instance's language.** Both rules, and the
-  line between prose and quoted vocabulary, are stated once in
-  [AGENTS.md § File naming](../AGENTS.md#file-naming). They are named here because this is the
-  step where they are obeyed or lost: nothing checks either mechanically, and an instruction
-  that models a sentence for the user is where the two are easiest to confuse - the model is
-  written in English, the saying of it follows `kb/CONVENTIONS.md`'s `language:`.
+- **Write it in English, and let the agent speak the instance's language.** The first rule, and
+  the line between prose and quoted vocabulary, are stated once in
+  [AGENTS.md § File naming](../AGENTS.md#file-naming), the second in
+  [AGENTS.md § Conversation language](../AGENTS.md#conversation-language). They are named here
+  because this is the step where they are obeyed or lost: nothing checks either mechanically, and
+  an instruction that models a sentence for the user is where the two are easiest to confuse -
+  the model is written in English, the saying of it follows `kb/CONVENTIONS.md`'s `language:`.
 
 ### A skill's H1 is a name, not an imperative
 
@@ -251,9 +264,9 @@ the next session to read before adding one.
 
 ### A skill's outbound reference is a plain path, not a link
 
-`tools/wikitool instructions sync` copies each `SKILL.md` byte for byte into
-`.agents/skills/<name>/` and `.claude/skills/<name>/` (§ Publishing, above) - a different depth
-than the source, and without the sibling files a relative link might expect. A markdown link
+`tools/wikitool instructions sync` copies each `SKILL.md` into
+`.agents/skills/<name>/` and `.claude/skills/<name>/` (§ Publishing, above; the generated
+language line it adds is no link) - a different depth than the source, and without the sibling files a relative link might expect. A markdown link
 correct at `instructions/<name>/SKILL.md` (`../session-setup.md`, `../../kb/CONTRACT.md`)
 resolves to a different, usually nonexistent, file once copied: the number of `../` segments
 that reaches a target from `instructions/` does not reach the same target from

instructions/dev/stack-build/SKILL.md

@@ -72,7 +72,7 @@ session, or a fresh one after `/clear` - assume the second, and work from the bo
    `instructions/dev/doc-pull-through.md` has the table of which document that is, per surface,
    and its step 3 for the one part that is not prose: a reference file whose headings moved needs
    `tools/wikitool docs toc --apply`, never a hand-written list. Prose you write here is English,
-   whatever language the session is held in - `AGENTS.md` § File naming has both language rules.
+   whatever language the session is held in - `AGENTS.md` § File naming has the rule for files, § Conversation language the one for what you say.
 
 6. **Publish and wait for CI** per `instructions/dev/publish-and-ci.md`: the local checks,
    `tools/wikitool publish`, then the run on the published commit.
@@ -94,7 +94,7 @@ session, or a fresh one after `/clear` - assume the second, and work from the bo
      session on Opus at high effort, which works from the body and the diff. That is why the
      three fixed points above are not optional.
 
-   Close with the fixed line, in the instance's KB language per `AGENTS.md` § File naming:
+   Close with the fixed line, in the instance's KB language per `AGENTS.md` § Conversation language:
 
    > #N is published and CI is green (run <id>). Next: `/stack-close` - here, or after `/clear`.
 

instructions/dev/stack-close/SKILL.md

@@ -115,7 +115,7 @@ always will.
    - **No `## Kette` section:** give no line, as before.
 
    Close the phase with exactly one of these fixed lines, in the instance's KB language per
-   `AGENTS.md` § File naming. A link is *ready* when it carries `kind/build` and neither
+   `AGENTS.md` § Conversation language. A link is *ready* when it carries `kind/build` and neither
    `status/incoming` nor `status/unconfirmed`:
 
    > #N is closed. Next in the chain "<name>": #M - `/stack-build #M`, here or after `/clear`.

instructions/dev/stack-dev/SKILL.md

@@ -66,7 +66,7 @@ are split that way.
    - **A short one** - an existing spec refreshed against the tree: continue in this session
      with `/stack-build #N`.
 
-   Close with the fixed line, in the instance's KB language per `AGENTS.md` § File naming:
+   Close with the fixed line, in the instance's KB language per `AGENTS.md` § Conversation language:
 
    > #N is ready. Next: `/stack-build #N` - here, or after `/clear`.