feat: Prosa ist kein Identifier - Link-Taxonomie als Enum, generierte Regionen mit Markern (4.0.0)

Files changed:
- .gitea/workflows/ci.yml
- AGENTS.md
- CHANGES.md
- VERSION
- instructions/CONTRACT.md
- instructions/link-taxonomy.md
- instructions/migrations/4.0.0-link-taxonomy.md
- instructions/setup-instance.md
- kb/CONTRACT.md
- kb/CONVENTIONS.md
- kb/CONVENTIONS.md.template
- kb/comparisons/COLLECTION.md
- kb/concepts/COLLECTION.md
- kb/entities/COLLECTION.md
- kb/sources/COLLECTION.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/blocks.py
- tools/chemenu/cli.py
- tools/chemenu/commands/cite_cmd.py
- tools/chemenu/commands/dist_cmd.py
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/commands/doctor.py
- tools/chemenu/commands/links_cmd.py
- tools/chemenu/commands/migrate_cmd.py
- tools/chemenu/commands/new_page.py
- tools/chemenu/commands/page_ops.py
- tools/chemenu/commands/run_budget.py
- tools/chemenu/commands/xref.py
- tools/chemenu/conventions.py
- tools/chemenu/corpus_diff.py
- tools/chemenu/frontmatter_io.py
- tools/chemenu/kb_collections.py
- tools/chemenu/kb_state.py
- tools/chemenu/links.py
- tools/chemenu/lint_core.py
- tools/chemenu/provenance.py
- tools/chemenu/sections.py
- tools/chemenu/tests/conftest.py
- tools/chemenu/tests/test_blocks.py
- tools/chemenu/tests/test_cite_cmd.py
- tools/chemenu/tests/test_conventions.py
- tools/chemenu/tests/test_dist_cmd.py
- tools/chemenu/tests/test_doctor.py
- tools/chemenu/tests/test_migrate_cmd.py
- tools/chemenu/tests/test_new_page.py
- tools/chemenu/tests/test_pipeline_l0.py
- tools/chemenu/tests/test_types_cmd.py
- tools/chemenu/tests/test_xref.py
- types/concept.schema.yaml
- types/entity.md
- types/entity.schema.yaml
- types/instruction.schema.yaml
- types/type-spec.md
- work/link-taxonomy-migration/README.md
- work/link-taxonomy-migration/plan.md

tools/README.md

@@ -39,12 +39,13 @@ tools/
     errors.py              ChemenuError / ValidationError / BackendError
     corpus_cache.py        one parsed corpus per commit, never cached while the tree is dirty
     kb_scan.py             page iteration/loading over kb/
+    blocks.py              generated regions in a page body, found by marker rather than by heading
+    links.py               labelled edges in `related:` - the graph's semantics as data, not prose
     kb_collections.py      collection discovery (a directory with COLLECTION.md), and what one declares about itself
     conventions.py         kb/CONVENTIONS.md: what this instance decided about authoring, as opposed to what the stack enforces
     type_resolver.py       type-spec loading and schema resolution
     lint_core.py           the lint checks and the report, with no CLI attached
     types_core.py          type-spec listing/description, with no CLI attached
-    sections.py            the section headings the tool reads and writes in a page body
     markdown_code.py       masks code spans/fences so a page may show wiki notation, not only use it
     version.py             the stack version: VERSION, the release stamp, the compatibility rule
     kb_state.py            the KB version (.wikitool-kb.json) and the migration chain
@@ -111,23 +112,29 @@ procedure written down in advance is one an agent can complete alone. Whether
 a human *actually* saw it is not enforced here - that question is answered in
 the eval layer (`evals/trajectory.py`, `clearance-ended-the-turn`).
 
-**Section names are a vocabulary, not literals - and not the stack's.** `xref add` writes into
-Relationships and See Also, and `cite add` owns the trailing Footnotes block, so those three
-headings are structure the tool matches on. *Which words they are* is the corpus's own answer:
-`conventions.py` reads them from `kb/CONVENTIONS.md`, `sections.py` resolves them on access
-(PEP 562, the way `config` resolves its paths), and no heading text is written down in Python
-except the pre-conventions fallback for an instance that has not declared one yet.
+**Nothing locates a region by its prose.** `xref` owns the links region and `cite` the footnotes
+region, and each is delimited by a `<!-- wikitool:<name> -->` marker pair (`blocks.py`). The
+heading inside is rendered from `kb/CONVENTIONS.md` and is replaced along with the rest of the
+region on every write - so no heading text exists in Python, and changing the declaration cannot
+split a page.
 
-Each slot has one canonical spelling - what the tool writes - plus aliases it still recognizes.
-That asymmetry is what let the wiki be translated page by page instead of atomically: an
-untranslated `## Relationships` is still found and appended to. Dropping an alias is therefore a
-breaking change for any page not yet converted, not a cleanup. Renaming a heading is a
-migration's job; no other command may do it as a side effect (see `cite_block_heading` in
-`provenance.py`, which exists solely so `cite sync` stays a no-op on an untranslated page).
+Both halves of that mattered. Matching on the heading made the KB language a compiler constant;
+*guessing* where the region ended - at the next heading, and before that at the end of the file -
+silently deleted content sitting after it on eight pages. `migrate verify` compares marker-pair
+counts for the same reason it compares wikilink counts: a dropped marker is invisible otherwise.
 
-Because the value is resolved rather than bound, nothing may capture it at import time - not a
-module constant, not an evaluated default argument. That is why `provenance.CITE_BLOCK_HEADING`
-is a module `__getattr__` and `render_cite_block(heading=None)` resolves inside the call.
+**A relationship label is data, not prose.** `related:` carries `- <label>: <target>`
+(`links.py`), the label drawn from `instructions/link-taxonomy.md` and authorised per
+destination by the *source* collection's `outbound:` block. The body bullet is a rendering of
+that, which is what removed the need to parse a German phrase back into a relationship - and why
+the vocabulary can be checked at all, after drifting to 152 distinct labels while it could not
+be. Both readers accept a bare title as an unlabelled edge: that is the shape a page is in
+between the machinery landing and the migration reaching it, and `lint` is what reports it.
+
+**An edge is authored in one direction.** `xref add` writes one, on the asserting page. The
+inbound view is rendered from the graph rather than stored, so navigation does not depend on
+anyone writing a mirror - and per-collection authorisation stays coherent, which it cannot be if
+the tool writes edges into a collection whose rules the author never read.
 
 **Generated output is never committed.** `reports/`, `.agents/skills/` and
 `.claude/skills/` are build output; `docs verify` carries canaries in both