docs(json-yaml): framing for JSON + YAML grammars

Frame the JSON/YAML grammar-gap addition (tree-sitter-json 0.24 +
tree-sitter-yaml 0.7, both ABI-current) plus their language servers, and
the free frontmatter/fence highlighting that falls out of the #122
injection engine (the markdown block query already injects yaml for `---`
frontmatter and toml for `+++`). Four decisions (Q#JY1-JY4), nine
acceptance tests. JSON is also the standing prerequisite for the Jupyter
.ipynb arc.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YJ9FQ832QwftJXCD9LeFan
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Levi Neuwirth 2026-07-15 17:00:45 +01:00
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# JSON + YAML grammars — framing (side quest, highlight family)
**Intent.** Add `tree-sitter-json` and `tree-sitter-yaml` grammars (plus
their language servers) to the bundle. Two config formats that pmacs
currently renders as plain text, and — the reason this is the natural
next side quest — the **honest gate on the Jupyter `.ipynb` path** (JSON)
and an **immediate payoff from the injection engine just shipped (#122)**:
the markdown block grammar's `injections.scm` already sets
`injection.language "yaml"` for `---` frontmatter and `"toml"` for `+++`
frontmatter, so registering YAML lights up YAML frontmatter highlighting
with zero extra wiring (TOML frontmatter already works — `toml` landed in
#118 and injections in #122). This is a mostly-additive grammar-gap-style
change, following the #118 pattern, with the frontmatter/fence synergy as
the demonstrable headline.
---
## Ground truth (as of `main` @ `56eb67e`, #121)
- **Adding a grammar** is a one-line `LanguageEntry` in
`crate::syntax::BUILTIN_LANGUAGES` (`name`, `extensions`, `loader`,
`highlights_query`, `injections_query`) + a `tree-sitter-foo` dep. The
Lua `buffer.after-load` path picks it up automatically; detection is
extension → LSP filetype → filename → shebang
(`resolve_active_language`).
- **Grammar name MUST equal the `pmacs.lsp.config.<name>` key** — grammar
detection wins over the filetype map, so the name it resolves is the id
the LSP client keys off (the #118 invariant; there's an acceptance test
that pins every grammar-gap language to its config key).
- **LSP configs** are `pmacs.lsp.config.<name> = … or { command, args,
[settings|init_options] }` (`builtin/runtime/lsp.lua`); no json/yaml
config today. `pmacs.lsp.filetypes` is the LSP-only extension fallback
(consulted only when `language_for_path` misses).
- **Injection synergy (#122).** The bundled `tree_sitter_md::
INJECTION_QUERY_BLOCK` contains:
- `((minus_metadata) @injection.content (#set! injection.language
"yaml"))` — `---`-fenced frontmatter,
- `((plus_metadata) @injection.content (#set! injection.language
"toml"))` — `+++`-fenced frontmatter,
- fenced code blocks via the dynamic info-string.
So a registered `yaml` grammar is injected into markdown frontmatter
automatically, and ` ```json `/` ```yaml `/` ```yml ` fences resolve
(`yml`→yaml is already in `default_injection_aliases`; `json` is the
bundled name).
**Confirmed crate facts** (probed against the registry + a build under
tree-sitter 0.26):
1. `tree-sitter-json` **0.24.8**`pub const LANGUAGE: LanguageFn` (via
`tree-sitter-language`, the modern shared ABI) + `HIGHLIGHTS_QUERY`.
Compiles and links under our tree-sitter 0.26. No `INJECTIONS_QUERY`
(JSON embeds nothing).
2. `tree-sitter-yaml` **0.7.2** — same shape (`LANGUAGE: LanguageFn`,
`HIGHLIGHTS_QUERY`, `tree-sitter-language` dep). Compiles under 0.26.
No `INJECTIONS_QUERY`.
3. Both are the ABI-current crates — **not** a `tree-sitter ^0.20` fork
(the dockerfile trap from #118). A single build confirmed link +
compile; runtime `set_language` is pinned by the ABI acceptance test.
---
## Decisions
### Q#JY1 — Two `LanguageEntry`s, self-contained highlights, no injections
Add `json` and `yaml` to `BUILTIN_LANGUAGES`, each
`highlights_query: &[…::HIGHLIGHTS_QUERY]` (self-contained, no
`; inherits:` delta), `injections_query: &[]`. Extensions:
- **json:** `.json`. (`.jsonc`/`.json5` — comment/trailing-comma variants
the plain JSON grammar rejects — are **deferred**; a `.jsonc` grammar
or a lenient mode is a separate call.)
- **yaml:** `.yaml`, `.yml`.
Root kinds (pinned by the ABI test): json `document`, yaml `stream`.
### Q#JY2 — LSP configs: `vscode-json-language-server` + `yaml-language-server`
- **json:** `vscode-json-language-server --stdio` from the **maintained
`vscode-langservers-extracted` bundle** — NOT the stale standalone
`vscode-json-languageserver` npm package. Schema-driven
diagnostics/completion; auto-associates well-known files
(`package.json`, `tsconfig.json`) via its schema store. The underlying
Microsoft JSON server is **MIT-licensed with no telemetry path**; its
only relevant outbound behavior is fetching remote `$schema` content.
**Remote schema retrieval stays enabled by default** — setting
`handledSchemaProtocols = {"file"}` would disable server-side HTTP but
then remote schemas fail unless pmacs implements the `vscode/content`
request (out of scope), so we leave it on and document the behavior.
- **yaml:** `yaml-language-server --stdio` (Red Hat).
Both servers stay **external** (installed by the user), adding **no
licensing payload** to pmacs; if either is ever bundled, retain its MIT +
dependency notices. Both **pull `workspace/configuration`** (the
mechanism that bit CMake in #117), so the config ships **non-nil empty
settings** matching the taplo/cmake precedent. **Implementation verifies
the exact `workspace/configuration` sections each real server requests
and pins those sections in the config + tests** — not merely that a
non-null settings table exists (if a server is not installed on the
build machine, the sections are derived from its source/docs and the
gap is noted, per the basedpyright machine-caveat precedent). Servers
activate only if installed; the grammar is the always-on value.
### Q#JY3 — Filetype fallback + alias entries
Add `pmacs.lsp.filetypes` entries (`json`→json, `yaml`/`yml`→yaml) as the
stable-id fallback (grammar detection wins in practice, same role as the
`cuda`/`lua` entries). `default_injection_aliases` already has `yml`→yaml;
`json`/`yaml` are bundled names needing no alias. Special *filenames*
(`.prettierrc`, `docker-compose.yml` is already `.yml`, extensionless
CI/config yaml) are **deferred** to the filename map as a follow-up.
### Q#JY4 — Frontmatter/fence highlighting is the headline, and it's free
No new injection wiring: registering `yaml` makes the existing markdown
`minus_metadata`→yaml injection resolve, and ` ```json `/` ```yaml `
fences resolve through the #122 engine. Acceptance proves both end to end
(this is the demonstrable payoff and the tie-back to injections).
---
## Bets
1. The two crates are ABI-current and drop in like the #118 grammar-gap
languages — verified by a build; the ABI test is the runtime pin.
2. The frontmatter/fence synergy needs zero engine changes — it falls out
of #122 + the markdown injection query.
3. The LSP `workspace/configuration` shape is the only real unknown;
empty-but-present settings + implementation-time verification against
the real servers is the mitigation (the #117 CMake lesson).
## Deferred (named)
- `.jsonc` / `.json5` (comments / trailing commas) — needs a lenient
grammar or variant entry.
- Special-filename detection for extensionless config files (`.prettierrc`,
CI yaml) via the filename map.
- JSON **schema** wiring (custom `json.schemas` / `yaml.schemas` settings)
beyond the servers' built-in schema stores.
- The Jupyter `.ipynb` arc itself (JSON is its prerequisite, not its
delivery).
## Acceptance
1. `builtin_languages_include_json_and_yaml` — entries present, claim
their extensions, ship non-empty highlights.
2. `json_grammar_loads_and_parses` — ABI: `set_language` + parse a JSON
object; root `document`, no error (the runtime ABI pin).
3. `yaml_grammar_loads_and_parses` — ABI: parse a YAML mapping; root
`stream`, no error.
4. `json_yaml_highlights_compile` — both highlights queries compile and
resolve several capture classes.
5. `language_for_path_resolves_json_yaml``.json`→json, `.yaml`/`.yml`→
yaml.
6. `json_yaml_align_with_lsp_configs` — grammar name == the
`pmacs.lsp.config.<name>` key (the #118 invariant).
7. **`yaml_frontmatter_injects_in_markdown`** — a markdown doc with a
`---\nkey: val\n---` frontmatter yields a `yaml` child layer that
highlights; **the headline synergy with #122**.
8. `json_fence_injects_in_markdown` — a ` ```json ` fence yields a `json`
child layer.
9. LSP config tests (m4-style): `pmacs.lsp.config.json`/`.yaml` present
with the expected command/args (json uses
`vscode-json-language-server`), and the settings table carries
**exactly the `workspace/configuration` sections each server
requests** — pinned, not merely asserted non-nil.
## Risks / interactions
- **LSP `workspace/configuration`** (Q#JY2) — the real risk; verified
against the servers at implementation time, empty-present settings as
the safe default.
- **Themes / injections** — untouched. This is pure grammar+detection
addition; it consumes the #122 engine, doesn't change it. No protocol
bump.
- **`.yml` vs `.yaml`** — both map to `yaml`; no collision with any
existing entry.