diff --git a/Cargo.lock b/Cargo.lock
index 46b8cd0..f0b1daa 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -423,6 +423,16 @@ dependencies = [
  "thiserror 2.0.18",
 ]
 
+[[package]]
+name = "codebook-tree-sitter-latex"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a3ab764ede0961a43ee3121cd8a71dd01d355f836181ebf2ede04f4c24636ca0"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
 [[package]]
 name = "codespan-reporting"
 version = "0.13.1"
@@ -2528,6 +2538,7 @@ checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6"
 name = "pmacs"
 version = "1.0.0"
 dependencies = [
+ "codebook-tree-sitter-latex",
  "crossbeam",
  "crossterm",
  "loro",
diff --git a/Cargo.toml b/Cargo.toml
index 051d109..e49da58 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -218,6 +218,21 @@ tree-sitter-yaml = "0.7"
 # alternative names `tree-sitter-markdown*` are forks of varying
 # maintenance status — pick the upstream one.
 tree-sitter-md = "0.5"
+# LaTeX / TeX (`.tex`/`.latex`/`.sty`/`.cls`) — the "basic LaTeX mode"
+# foothold and the tier-1 detection substrate for the inline-math arc (lane
+# framing `docs/latex-grammar-math-substrate-framing.md`). The canonical crate name
+# `tree-sitter-latex` is squatted by a broken 0.1.0 repackage that ships no
+# `scanner.c` for its declared external tokens and therefore CANNOT LINK
+# (undefined `tree_sitter_latex_external_scanner_*`). `codebook-tree-sitter-latex`
+# is a linkable republish of the real, maintained `latex-lsp/tree-sitter-latex`
+# (MIT, texlab's author) modernized to the `LanguageFn` shim: it ships
+# `scanner.c`, exports `LANGUAGE` over `tree-sitter-language 0.1` (tree-sitter
+# dev-only, shared ABI crate — no second core in the graph), and its
+# `grammar.js`/`scanner.c` are byte-identical to upstream (provenance diff
+# discharged in the framing). It exports NO query constants, so highlighting
+# uses the in-repo overlay `builtin/queries/latex/highlights.scm` (the first
+# such overlay; `include_str!`'d in `crate::syntax::BUILTIN_LANGUAGES`).
+codebook-tree-sitter-latex = "0.6"
 # T M4.4 process supervisor: signal sending without `unsafe`. Keep
 # the feature surface tight to keep build time low. `poll` feeds the
 # compile-mode group readers (cancellable poll-based reads, Q#CM3).
diff --git a/builtin/queries/latex/highlights.scm b/builtin/queries/latex/highlights.scm
new file mode 100644
index 0000000..69f36f1
--- /dev/null
+++ b/builtin/queries/latex/highlights.scm
@@ -0,0 +1,298 @@
+; LaTeX highlights — vendored from nvim-treesitter (Apache-2.0) and reconciled
+; onto pmacs' recognized capture set (src/highlight.rs; framing Q#LX2 / F4).
+;
+; Reconciliation vs the verbatim upstream (previous commit):
+;   * @spell / @nospell markers stripped — meaningless to pmacs, and a
+;     same-node @nospell risks clobbering the real capture.
+;   * The 8 predicate-gated patterns (#eq? / #any-of? / #lua-match?) removed:
+;     pmacs evaluates only `#is? local` predicates, so unevaluated they would
+;     over-match every generic command (as \if-conditional / emphasis) and
+;     every line_comment (as a magic directive). Re-instating them is deferred
+;     to predicate support. This also drops the only @markup.italic/@markup.strong
+;     uses, so those need no remap.
+;   * Fall-through captures remapped onto the recognized set:
+;       @module        -> @keyword         (\begin/\end/sectioning commands)
+;       @label         -> @type            (environment / theorem names)
+;       @markup.heading -> @keyword.control (section-title text)
+;       @markup.link*  -> @constant        (labels, refs, citations, urls)
+;       @markup.math   -> @string          (inline/displayed formulas)
+; Grammar node names are UNCHANGED from upstream — Query::new compiling this
+; against the bundled grammar is the node-name compatibility gate (acceptance 3).
+
+; General syntax
+(command_name) @function
+
+(caption
+  command: _ @function)
+
+; \text, \intertext, \shortintertext, ...
+(text_mode
+  command: _ @function
+  content: (curly_group
+    (_) @none))
+
+; Variables, parameters
+(placeholder) @variable
+
+(key_value_pair
+  key: (_) @variable.parameter
+  value: (_))
+
+(curly_group_spec
+  (text) @variable.parameter)
+
+(brack_group_argc) @variable.parameter
+
+[
+  (operator)
+  "="
+  "_"
+  "^"
+] @operator
+
+"\\item" @punctuation.special
+
+(delimiter) @punctuation.delimiter
+
+(math_delimiter
+  left_command: _ @punctuation.delimiter
+  left_delimiter: _ @punctuation.delimiter
+  right_command: _ @punctuation.delimiter
+  right_delimiter: _ @punctuation.delimiter)
+
+[
+  "["
+  "]"
+  "{"
+  "}"
+] @punctuation.bracket ; "(" ")" has no syntactical meaning in LaTeX
+
+; General environments
+(begin
+  command: _ @keyword
+  name: (curly_group_text
+    (text) @type))
+
+(end
+  command: _ @keyword
+  name: (curly_group_text
+    (text) @type))
+
+; Definitions and references
+(new_command_definition
+  command: _ @function.macro)
+
+(old_command_definition
+  command: _ @function.macro)
+
+(let_command_definition
+  command: _ @function.macro)
+
+(environment_definition
+  command: _ @function.macro
+  name: (curly_group_text
+    (_) @type))
+
+(theorem_definition
+  command: _ @function.macro
+  name: (curly_group_text_list
+    (_) @type))
+
+(paired_delimiter_definition
+  command: _ @function.macro
+  declaration: (curly_group_command_name
+    (_) @function))
+
+; NOTE: this grammar cut (codebook 0.6.1, ~Dec 2025) uses distinct
+; `curly_group_label`/`curly_group_label_list` nodes for label commands, where
+; newer latex-lsp (which nvim's query targets) unified them onto
+; `curly_group_text`. Kept grammar-accurate here (acceptance 3 is the gate).
+(label_definition
+  command: _ @function.macro
+  name: (curly_group_label
+    (_) @constant))
+
+(label_reference_range
+  command: _ @function.macro
+  from: (curly_group_label
+    (_) @constant)
+  to: (curly_group_label
+    (_) @constant))
+
+(label_reference
+  command: _ @function.macro
+  names: (curly_group_label_list
+    (_) @constant))
+
+(label_number
+  command: _ @function.macro
+  name: (curly_group_label
+    (_) @constant)
+  number: (_) @constant)
+
+(citation
+  command: _ @function.macro
+  keys: (curly_group_text_list) @constant)
+
+(hyperlink
+  command: _ @function
+  uri: (curly_group_uri
+    (_) @constant))
+
+(glossary_entry_definition
+  command: _ @function.macro
+  name: (curly_group_text
+    (_) @constant))
+
+(glossary_entry_reference
+  command: _ @function.macro
+  name: (curly_group_text
+    (_) @constant))
+
+(acronym_definition
+  command: _ @function.macro
+  name: (curly_group_text
+    (_) @constant))
+
+(acronym_reference
+  command: _ @function.macro
+  name: (curly_group_text
+    (_) @constant))
+
+(color_definition
+  command: _ @function.macro
+  name: (curly_group_text
+    (_) @constant))
+
+(color_reference
+  command: _ @function.macro
+  name: (curly_group_text
+    (_) @constant)?)
+
+; Sectioning
+(title_declaration
+  command: _ @keyword
+  options: (brack_group
+    (_) @keyword.control)?
+  text: (curly_group
+    (_) @keyword.control))
+
+(author_declaration
+  command: _ @keyword
+  authors: (curly_group_author_list
+    (author)+ @keyword.control))
+
+(chapter
+  command: _ @keyword
+  toc: (brack_group
+    (_) @keyword.control)?
+  text: (curly_group
+    (_) @keyword.control))
+
+(part
+  command: _ @keyword
+  toc: (brack_group
+    (_) @keyword.control)?
+  text: (curly_group
+    (_) @keyword.control))
+
+(section
+  command: _ @keyword
+  toc: (brack_group
+    (_) @keyword.control)?
+  text: (curly_group
+    (_) @keyword.control))
+
+(subsection
+  command: _ @keyword
+  toc: (brack_group
+    (_) @keyword.control)?
+  text: (curly_group
+    (_) @keyword.control))
+
+(subsubsection
+  command: _ @keyword
+  toc: (brack_group
+    (_) @keyword.control)?
+  text: (curly_group
+    (_) @keyword.control))
+
+(paragraph
+  command: _ @keyword
+  toc: (brack_group
+    (_) @keyword.control)?
+  text: (curly_group
+    (_) @keyword.control))
+
+(subparagraph
+  command: _ @keyword
+  toc: (brack_group
+    (_) @keyword.control)?
+  text: (curly_group
+    (_) @keyword.control))
+
+; File inclusion commands
+(class_include
+  command: _ @keyword.import
+  path: (curly_group_path) @string)
+
+(package_include
+  command: _ @keyword.import
+  paths: (curly_group_path_list) @string)
+
+(latex_include
+  command: _ @keyword.import
+  path: (curly_group_path) @string.special.path)
+
+(verbatim_include
+  command: _ @keyword.import
+  path: (curly_group_path) @string.special.path)
+
+(import_include
+  command: _ @keyword.import
+  directory: (curly_group_path) @string.special.path
+  file: (curly_group_path) @string.special.path)
+
+(bibstyle_include
+  command: _ @keyword.import
+  path: (curly_group_path) @string)
+
+(bibtex_include
+  command: _ @keyword.import
+  paths: (curly_group_path_list) @string.special.path)
+
+(biblatex_include
+  "\\addbibresource" @keyword.import
+  glob: (curly_group_glob_pattern) @string.regexp)
+
+(graphics_include
+  command: _ @keyword.import
+  path: (curly_group_path) @string.special.path)
+
+(svg_include
+  command: _ @keyword.import
+  path: (curly_group_path) @string.special.path)
+
+(inkscape_include
+  command: _ @keyword.import
+  path: (curly_group_path) @string.special.path)
+
+(tikz_library_import
+  command: _ @keyword.import
+  paths: (curly_group_path_list) @string)
+
+; Math
+[
+  (displayed_equation)
+  (inline_formula)
+] @string
+
+(math_environment
+  (_) @string)
+
+; Comments
+[
+  (line_comment)
+  (block_comment)
+  (comment_environment)
+] @comment
diff --git a/docs/latex-grammar-math-substrate-framing.md b/docs/latex-grammar-math-substrate-framing.md
new file mode 100644
index 0000000..d27e73b
--- /dev/null
+++ b/docs/latex-grammar-math-substrate-framing.md
@@ -0,0 +1,426 @@
+# LaTeX grammar + math parser — framing (inline-math substrate)
+
+**Revision 3 — pre-implementation. Ground truth: canonical `main` @
+`96d0bae`, protocol v19, 2026-07-23. Status: framing only; no
+implementation.** Rev 1's pmacs-side scouting passed review with every
+in-repo anchor verified exactly; rev 2 corrected the external crate ground
+truth (the originally named crate provably cannot link) and refreshed the
+in-flight-lane snapshot; rev 3 folds in two provenance-wording corrections —
+the fork-vs-upstream attribution and the now-discharged provenance diff — and
+relaxes the `Cargo.toml` sequencing note. See §0.1 for the changelog.
+
+Parent arc: `docs/inline-math-framing.md` — currently an **untracked,
+desktop-only framing** not yet committed to the repo, so this path will not
+resolve on a fresh clone; committing it as its own docs PR (or listing it in
+the handoff's machine-local doc inventory) is a tracked follow-up. That note
+frames the full four-tier inline-math renderer; its Tier 4 (GPU render) lands on
+`pmacs-gpu/src/main.rs`, the render path that folding and any future math
+draw pass also contend for. **This lane deliberately carves out only the
+frontend-agnostic, conflict-free substrate** — the parts that can land now,
+in a sibling worktree, without touching a single file the two in-flight
+efforts will own.
+
+## 0. Why this lane, why now (parallel-safety)
+
+Two efforts are in flight; both share files with this lane, and the
+disjointness must be described against their **current** state, not a stale
+one (F5, verified 2026-07-23):
+
+- **folding** (`folding` branch) is at **rev 5, APPROVED, Stage 1
+  implementing** (head `40a820a`, clean worktree) — not framing-only. Its
+  eventual touch set owns `semantic_render.rs`, `src/overlay.rs`,
+  `src/syntax.rs` (the `ParseViewHandle` reads at `:696`/`:706`),
+  `src/daemon.rs` (grid render + `dispatch_key` pre-edit unfold), the Lua
+  command/dispatch layer + `src/lua_bindings/mod.rs`, **both frontends'
+  gutter/render**, and `pmacs-gpu/src/main.rs` (fold mirror).
+- **gpu-invocation** (`gpu-invocation` branch) is **not framing-only either**:
+  its worktree carries **uncommitted implementation right now, including edits
+  to root `Cargo.toml`** — one of this lane's two shared files. It will own
+  `src/main.rs`, `pmacs-gpu/src/main.rs` (argv/startup),
+  `pmacs-gpu/src/attach.rs`, root `Cargo.toml` (`default-run`), and the README.
+- **inline-math Tier 4** (deferred, this lane's downstream) would own
+  `pmacs-gpu/src/main.rs` (the render path — the three-way hotspot).
+
+This lane touches **none** of those code paths. Its entire footprint is: one
+`BUILTIN_LANGUAGES` append, one `Cargo.toml` dependency line, one new in-repo
+query overlay file, and one new pure module `src/math_parse.rs`. The only two
+shared files, with disjointness re-verified:
+
+- `src/syntax.rs` — a **localized append to the language table at `:1095`**
+  (after the `yaml` entry's `},`, before `];` at `:1096`), disjoint from
+  folding's `ParseViewHandle` reads at `:696`/`:706`.
+- root `Cargo.toml` — a **dependency line** in the grammar block
+  (`:142`–`:219`). gpu-invocation's live edit is the `default-run` key in
+  `[package]`; **no `default-run` key exists yet**, and the grammar dep block
+  is a different region ~100 lines away. The two edits are **disjoint hunks
+  that git auto-merges cleanly** — the same config-registry ∥ Vterm precedent
+  this section cites — so no ordering is technically required. Flagging the
+  overlap is coordination courtesy, not a merge risk.
+
+This is the localized-single-region-append pattern that already rebased with
+**zero conflicts** when config-registry and Vterm Stage 1 shared
+`editor.rs`/`mod.rs` (`docs/active-work.md`, "Closed since the last
+snapshot"). Its precondition — agree the file split before either lane starts,
+keep each lane's footprint in shared files to a localized region — holds here
+by construction; the now-active `Cargo.toml` overlap is disjoint (above) and
+needs only coordination courtesy.
+
+## 0.1 Revision history
+
+### Round 1 (rev 1 → rev 2)
+
+- **F1 (severe).** Rev 1's `tree-sitter-latex` 0.1.0 (crates.io) **cannot
+  link.** It is a third-party repackage (publisher `cijiugechu`) of an old
+  latex-lsp grammar snapshot; its declared repo
+  `github.com/tree-sitter/tree-sitter-latex` **does not exist** (404, and the
+  crate's VCS sha is absent from latex-lsp history). The grammar declares
+  external tokens but the tarball **ships no `scanner.c`**, and its `build.rs`
+  compiles the scanner only "if it exists." Proven empirically: an offline
+  path-dep build fails with undefined
+  `tree_sitter_latex_external_scanner_scan`/`_serialize`/`_deserialize`. The
+  rev-1 scouted facts (`LANGUAGE: LanguageFn`, shim ABI compatibility) were
+  each individually true — docs.rs cannot surface a *link* failure, which is
+  why the scout missed it. **Fix: Q#LX1 re-based on a working vehicle (F2).**
+- **F2 (severe).** A working, verified vehicle exists:
+  **`codebook-tree-sitter-latex` 0.6.1** (26k downloads). See Q#LX1.
+- **F3 (severe).** Q#LX2's vendoring source did not exist: latex-lsp ships
+  **no `queries/` directory** (its `include = ["queries/*"]` is vestigial),
+  and no first-party LaTeX `highlights.scm` exists anywhere. **Fix: Q#LX2
+  re-pointed at nvim-treesitter's query.**
+- **F4 (major).** Q#LX2's "real work" is broader than capture renaming — the
+  fall-through classes and predicate-support gap are now named in Q#LX2.
+- **F5 (major).** §0's in-flight snapshot was stale (folding is rev 5 /
+  approved / implementing; gpu-invocation has live uncommitted `Cargo.toml`
+  edits). §0 rewritten to reality; the disjointness argument survives with one
+  added sequencing obligation.
+- **F6 (minor).** Parser is **~500 lines** (parent framing, Tier 2 + the
+  integration table), not ~1,000. `LanguageEntry` has **six** fields.
+  `math_parse` sorts **before** `mcp` in `src/lib.rs` (alphabetical). The
+  0.6.1 crate is **~3.1 MB compressed**. All corrected below.
+
+### Round 2 (rev 2 → rev 3)
+
+- **R2-1.** Corrected the source attribution: the crate is a republish **from
+  the codebook project's fork** of `latex-lsp/tree-sitter-latex` (the fork
+  modernized the bindings to the `LanguageFn` shim and renamed the crate), not
+  a cut from an upstream `latex-lsp` commit. GitHub serves fork-network objects
+  through the parent repo's API, which made the fork commit `948b89c` look
+  upstream in rev 1/2. §2 fixed.
+- **R2-2.** The Q#LX1 provenance-diff gate is **discharged, not deferred**: the
+  diff against `latex-lsp` master is byte-identical on `grammar.js`/`scanner.c`
+  (460 node types in both; metadata-only drift in
+  `grammar.json`/`node-types.json`); the sole residual is generated `parser.c`,
+  covered by the parse smokes. §2 and Q#LX1 now record the result instead of
+  the obligation.
+- **R2-3.** Relaxed §0's `Cargo.toml` note: the dep append and gpu-invocation's
+  `default-run` key are disjoint hunks ~100 lines apart that git auto-merges
+  cleanly (the cited config-registry ∥ Vterm precedent). Kept as coordination
+  courtesy; dropped the inaccurate "can't assume a clean auto-merge" rationale.
+
+## 1. What ships
+
+- **Stage 1 — LaTeX/TeX syntax highlighting.** A bundled LaTeX grammar
+  (Q#LX1) plus a vendored highlights overlay (Q#LX2) lights up `.tex` /
+  `.latex` / `.sty` / `.cls` buffers. Self-contained, user-visible, shippable
+  as its own PR. This is the "basic LaTeX mode" foothold and the tier-1
+  detection substrate the inline-math arc needs.
+- **Stage 2 — math parser: DEFERRED by decision (Q#LX5).** The pure
+  `src/math_parse.rs` recursive-descent parser is framed but **not built in
+  this lane** — the reviewer and author concur it should land beside its
+  Tier 3 layout consumer, not ahead of it. Recorded in §Deferred with its
+  rationale so the decision is not re-litigated.
+
+Also deferred to the inline-math arc proper (§Deferred): Tier 3 layout,
+Tier 4 GPU render, and instance-side `(math_environment) @math` injection
+detection.
+
+## 2. Ground truth (scouted 2026-07-23, `main` @ `96d0bae`; pmacs-side
+anchors verified in review, external facts corrected per §0.1)
+
+### Grammar table
+
+- **`LanguageEntry` struct — `src/syntax.rs:766-801`**, **six** fields:
+  `name` (`:769`), `extensions: &[&str]` (`:774`),
+  `loader: fn() -> tree_sitter::Language` (`:778`),
+  `highlights_query: &[&str]` (`:789`), `locals_query: &[&str]` (`:793`),
+  `injections_query: &[&str]` (`:800`). There is no `tags`/`filename`/`shebang`
+  field — extensions are the only Rust-side detection signal.
+- **`BUILTIN_LANGUAGES` table — `src/syntax.rs:816` … `];` at `:1096`.** A new
+  entry appends after the `yaml` entry's `},` at `:1095`. The "adding a
+  grammar" checklist is documented in-place at `:803-815`.
+- Example entry, verbatim (`src/syntax.rs:985-992`):
+  ```rust
+  LanguageEntry {
+      name: "python",
+      extensions: &["py", "pyi"],
+      loader: || tree_sitter_python::LANGUAGE.into(),
+      highlights_query: &[tree_sitter_python::HIGHLIGHTS_QUERY],
+      locals_query: &[],
+      injections_query: &[],
+  },
+  ```
+- Grammar crate deps live in `Cargo.toml:136-219` (`tree-sitter = "0.26"` at
+  `:136`; grammar crates `:142`–`:219`).
+
+### Detection chain
+
+- The `extensions` field drives `language_name_for_extension`
+  (`src/syntax.rs:1223`) and `language_name_for_path` (`:1235`).
+- The full precedence chain (PR #132 modeline work) is Lua,
+  `detect_buffer_language` at `builtin/runtime/syntax.lua:452-466`: **modeline
+  → grammar extension → LSP filetype map → filename map → shebang.** Because
+  grammar-extension detection sits *ahead* of the LSP filetype map, adding
+  `tex`/`latex`/`sty`/`cls` to the new entry's `extensions` **wires the whole
+  chain with no Lua edit**.
+
+### Query sourcing
+
+- **No in-repo `.scm` highlight overlays exist today.** Every grammar sources
+  its queries from crate-exported `&'static str` constants (naming varies:
+  `HIGHLIGHTS_QUERY`, `HIGHLIGHT_QUERY`, `HIGHLIGHT_QUERY_BLOCK`; documented at
+  `src/syntax.rs:779-800`). The CUDA entry (`:919-923`) shows queries composed
+  as a **slice of fragments** in the field.
+- The only `.scm` in the tree is `audit/audit-rules.scm`, pulled via
+  `include_str!` at `src/audit/mod.rs:76` — the sole precedent for shipping
+  static query text from a repo file.
+- **Highlight-capture handling** (F4): the prefix-walk at
+  `src/highlight.rs:189` already absorbs `@function.macro`, `@keyword.*`,
+  `@string`, `@comment`, and `@punctuation.*`. But `@markup.*` (headings,
+  italic, bold, math), `@module`, and `@label` **fall through to default
+  style** — i.e. the most LaTeX-distinctive content would paint as plain text
+  unless the vendored query's captures are renamed onto the recognized set.
+- **Predicate support** (F4): pmacs evaluates only the `#is? local` property
+  predicate; `#match?` / `#eq?` / `#any-of?` / `#lua-match?` are **silently
+  ignored** for every grammar (pre-existing, not a blocker). The nvim query
+  has 8 such uses that must be curated out or accepted as benign over-matching.
+
+### Injection seam (future math detection)
+
+- `collect_injection_matches` (`src/syntax.rs:375-427`) is the capture-
+  consumption point: it reads `@injection.content` (`:381`) and
+  `injection.language` (`:385-388`), plus `#set!` properties (`:397-404`).
+  Child-language resolution is `resolve_injected_language` (`:304`). The
+  markdown→rust fenced-code injection is the working precedent. A future
+  `(math_environment) @injection.content` + `#set! injection.language "math"`
+  hooks in here unchanged (Q#LX4, deferred).
+
+### Module registration & tests
+
+- Crate modules are declared in the alphabetized `pub mod` block at
+  `src/lib.rs:42-142`; `mod math_parse;` sorts **before** `mcp` (`:100`).
+- Grammar test convention (CUDA template, `src/syntax.rs:2130-2221`): a table
+  guard `builtin_languages_include_<lang>`, a smoke test
+  `<lang>_grammar_loads_and_parses_*` (`reg.language(...)` → parse → assert
+  root kind + `!has_error()`), a highlight-resolve test, and an extension-
+  resolution test. End-to-end paint template: `src/highlight.rs:1296-1346`.
+- **Greenfield confirmed** — no `math`/`latex`/`tex` code anywhere in `src/`,
+  `builtin/`, `pmacs-gpu/`, `pmacs-protocol/`.
+
+### Crate facts (external, corrected + reviewer-verified 2026-07-23)
+
+- **Rejected — `tree-sitter-latex` 0.1.0.** Broken repackage; dead declared
+  repo; **no `scanner.c`** for its declared external tokens; proven offline
+  link failure (undefined `tree_sitter_latex_external_scanner_*`). Not
+  linkable at any pin. (F1.)
+- **Chosen — `codebook-tree-sitter-latex` 0.6.1** (26k downloads,
+  ~3.1 MB compressed). A republish **from the codebook project's fork of
+  `latex-lsp/tree-sitter-latex`** (the real, maintained grammar — MIT,
+  texlab's author). The fork **modernized the bindings to the `LanguageFn`
+  shim and renamed the crate**; genuine `latex-lsp` master still carries
+  old-style bindings (`tree-sitter = 0.24.1` as a *direct* dependency, no
+  shim). (Rev 1/2 mis-attributed this to a Dec-2025 upstream `latex-lsp`
+  commit — GitHub serves fork-network objects through the parent repo's
+  commit/contents API, so the fork's commit `948b89c`, whose `lib.rs` already
+  carries the `codebook_tree_sitter_latex` name, looked upstream.) It **ships
+  `scanner.c`**, exports **`LANGUAGE: LanguageFn`** over
+  `tree-sitter-language 0.1` with `tree-sitter` **dev-only** — the exact shim
+  pattern every pmacs grammar uses. Verified end-to-end: builds against
+  `tree-sitter 0.26` and parses a document containing a **verbatim
+  environment** (which exercises the external scanner) → root kind
+  `source_file`, no errors. The canonical name `tree-sitter-latex` is squatted
+  by the broken crate, hence the `codebook-` prefix.
+- **Provenance diff — run, not deferred (R2-2).** The 0.6.1 crate was diffed
+  against genuine `latex-lsp` master: `grammar.js` and `scanner.c` — the
+  grammar definition and the hand-written C, the security-relevant surfaces —
+  are **byte-identical**. `grammar.json` / `node-types.json` differ **only** by
+  newer tree-sitter-cli output metadata (supertype population, extra flags):
+  **460 node types in both**, with type sets, named flags, and rule counts all
+  identical. The **sole residual** is `parser.c`, which is generated and not
+  committed upstream, so it cannot be diffed — it is exercised by the parse
+  smokes (acceptance 2), and an optional full discharge is regenerating it with
+  `tree-sitter-cli` at implementation time.
+
+## 3. Decisions
+
+### Q#LX1 — Bundle `codebook-tree-sitter-latex` 0.6.1
+
+Add `codebook-tree-sitter-latex = "0.6"` to the `Cargo.toml` grammar block;
+loader is `|| codebook_tree_sitter_latex::LANGUAGE.into()` (confirmed against
+the crate's `[lib] name = "codebook_tree_sitter_latex"`). This is the linkable
+republish from the codebook project's fork of `latex-lsp/tree-sitter-latex`,
+which modernized the bindings to the `LanguageFn` shim (§2); the
+originally-named `tree-sitter-latex` 0.1.0 is rejected as unlinkable (§2, F1).
+ABI is fine via the `tree-sitter-language` shim, exactly as every current
+grammar. The provenance concern (dirty-tree publish, squatted name) is
+**discharged, not deferred**: the diff against `latex-lsp` master is
+byte-identical on `grammar.js`/`scanner.c`, with only tree-sitter-cli metadata
+drift elsewhere and generated `parser.c` as the sole residual (§2, R2-2).
+Rejected: vendoring generated `parser.c`/`scanner.c` directly (compile +
+maintenance burden the crate absorbs) and re-pinning `tree-sitter`
+(unnecessary — the shim decouples us).
+
+### Q#LX2 — Vendor nvim-treesitter's highlights query (no first-party source exists)
+
+latex-lsp ships **no** `queries/` directory and no first-party
+`highlights.scm` exists anywhere (F3). Vendor **nvim-treesitter's
+`queries/latex/highlights.scm`** (342 lines, **Apache-2.0** — compatible with
+pmacs' `MIT OR Apache-2.0`; Helix's MPL-2.0 version is the fallback), host it
+at `builtin/queries/latex/highlights.scm`, and wire it into the entry's
+`highlights_query` via `include_str!` (the `audit-rules.scm` precedent). This
+establishes the first **in-repo grammar-query overlay convention**, which the
+ruby/php/html/css backlog then reuses.
+
+The **real work** (F4), beyond copying the file:
+1. **Capture reconciliation.** Rename/curate the query's `@markup.*`,
+   `@module`, and `@label` captures onto pmacs' recognized set
+   (`src/highlight.rs:189`) or they paint as default — and those are the
+   LaTeX-distinctive captures (headings, emphasis, math, environment names).
+2. **Predicate curation.** The 8 `#match?`/`#eq?`/`#any-of?`/`#lua-match?`
+   uses are silently ignored (§2); curate them out, or accept the resulting
+   over-matching, per rule.
+3. **Node-name compatibility.** Acceptance test 3 (`Query::new` compiles the
+   vendored query against the chosen grammar, §6) **doubles as the
+   grammar/query node-name compatibility check** — it is the test that catches
+   a grammar-version/query mismatch.
+
+Prefer `include_str!` of a `.scm` file over an in-source `&'static str` const
+so the query stays diffable and lintable as query source.
+
+### Q#LX3 — Extensions and detection
+
+`extensions: &["tex", "latex", "sty", "cls"]`. A single `BUILTIN_LANGUAGES`
+append at `:1095` wires the full detection chain (grammar-extension precedes
+the LSP filetype map in `syntax.lua:457`). No Lua edit; no
+modeline/filename/shebang changes.
+
+### Q#LX4 — Locals and injections empty for v0
+
+`locals_query: &[]`, `injections_query: &[]`. LaTeX has no lexical-scope
+locals worth shipping in v0. The `(math_environment) @math` injection — the
+instance-side, wire-authoritative alternative to the inline-math framing's
+frontend-local detection — is **deferred to the inline-math arc**; it hooks
+`collect_injection_matches` (`syntax.rs:375-427`) unchanged when a `"math"`
+layer exists. Verbatim/`listings`/`minted` code-block injections are a later
+quality pass.
+
+### Q#LX5 — The math parser is deferred, not front-run (decided)
+
+`src/math_parse.rs` (LaTeX math → the `MathNode` AST in
+`docs/inline-math-framing.md` §Tier 2, **~500 lines** + a ~200-entry symbol
+map) is pure, dependency-free, and conflict-free. Reviewer and author concur:
+**defer it** and land it beside its Tier 3 layout consumer. Rationale, beyond
+the no-build-ahead discipline (folding refuses `BlockAdornments`;
+gpu-invocation refuses `FILE`):
+
+- **No design pressure until layout exists.** The parent framing places the
+  hard part in Tier 3 layout; the `MathNode` shape is only validated once
+  layout consumes it. Freezing the AST now risks rework.
+- **The parallelization argument is void.** The parser is conflict-free *by
+  construction* — it can land at any time without lane contention — so there
+  is nothing to gain by front-running it. Front-running only trades that free
+  optionality for speculative, unexercised code.
+
+Stage 1 (grammar) therefore is this lane's shippable PR; the parser lands with
+the inline-math arc. Recorded here so it is not re-opened — the defer is
+ratified by the user's approval of this framing, per the workflow (author +
+reviewer concurrence proposes it; approval decides it).
+
+### Q#LX6 — No protocol, frontend, or GPU change in this lane
+
+No wire type, no `pmacs-protocol` touch, no TUI/GPU change. Stage 1 is a pure
+instance-side grammar-table addition. This is what keeps the lane orthogonal
+to both in-flight efforts.
+
+## 4. Categorical bets
+
+1. **The `LanguageFn` shim makes crate-version skew a non-issue.** Every
+   grammar already crosses the `tree-sitter 0.26` boundary through
+   `tree-sitter-language`; `codebook-tree-sitter-latex` is no different —
+   confirmed by a real build. The linkability risk was in the *scanner*, not
+   the shim, and is resolved by choosing a crate that ships `scanner.c` (F1/F2).
+2. **LaTeX highlighting is worth ~3.1 MB of grammar.** It is the largest
+   single grammar in the tree — a real binary-size and compile-time cost —
+   justified by being the LaTeX-mode foothold and a heavily-used authoring
+   format. A Cargo feature-gate is a v1 escape hatch if the size bites builds
+   that never edit `.tex`.
+3. **An in-repo query overlay is a convention to establish, not a blocker.**
+   It generalizes to every grammar crate that ships no Rust query constant —
+   directly unblocking the ruby/php/html/css backlog.
+4. **A verified republish beats a canonical-but-broken name.** The squatted
+   `tree-sitter-latex` name would have been the "obvious" pick and does not
+   link; the provenance diff (Q#LX1, now discharged — grammar and scanner
+   byte-identical to upstream) is the cost, already paid, of using the working
+   republish safely.
+
+## 5. Deferred (named)
+
+- **Math parser `src/math_parse.rs`** — decided defer (Q#LX5); lands with
+  Tier 3 layout, not this lane.
+- **Tier 3 math layout** (`src/math_layout.rs`, a font crate — `read-fonts`
+  or `ttf-parser` — + OpenType MATH-table box layout). New file, no contested
+  touch, but pulls a dependency and has real complexity; belongs to the
+  inline-math arc beside its GPU consumer.
+- **Tier 4 GPU render** (`pmacs-gpu/src/main.rs` render path). The three-way
+  hotspot; wait for folding and gpu-invocation to settle before opening it.
+- **Instance-side `(math_environment) @math` injection detection** + a `"math"`
+  `BUILTIN_LANGUAGES` layer (the wire-authoritative upgrade over the framing's
+  frontend-local scan).
+- **A real `latex-mode.lua`**: texlab LSP config, sectioning folds (rides
+  Arc 6), `\ref`/`\label` navigation, environment/snippet completion,
+  auto-`\end{}`. Full-document LaTeX, not math rendering.
+- **Curated highlight refinements** beyond the vendored query, including
+  re-instating the ignored predicates should pmacs' predicate support grow;
+  verbatim/`listings`/`minted` code injections.
+
+## 6. Acceptance
+
+**Stage 1 (grammar).** Tests follow the CUDA convention
+(`src/syntax.rs:2130-2221`) + the paint template (`src/highlight.rs:1296`):
+
+1. **Table guard** `builtin_languages_include_latex`: the entry exists, claims
+   `tex`/`latex`/`sty`/`cls`, and carries the overlay highlights fragment.
+2. **Load-and-parse smoke** `latex_grammar_loads_and_parses`:
+   `reg.language("latex")`, parse a minimal
+   `\documentclass{article}\begin{document}Hello $x$\end{document}` **plus a
+   `verbatim` environment** (to exercise the external scanner), assert the
+   root node kind `source_file` and `!has_error()`.
+3. **Highlights resolve + node-name compatibility**
+   `latex_highlights_resolve`: `reg.highlights_query("latex")` compiles the
+   vendored query against the grammar (this is also the grammar/query
+   compatibility gate, Q#LX2), and a `\command`, a `{group}`, and a
+   sectioning/emphasis construct paint the reconciled capture classes (not
+   default).
+4. **Extension resolution** `language_for_path_resolves_latex_extensions`:
+   `foo.tex` / `foo.latex` / `pkg.sty` / `cls.cls` all resolve to `"latex"`.
+5. **Full gate suite** per `CLAUDE.md`: `cargo fmt --check`; `cargo clippy
+   --workspace --all-targets -- -D warnings`; `cargo test --lib`; `cargo test
+   --lib --features crdt`; the touched acceptance suites; `cargo test --test
+   m4_acceptance -- --skip basedpyright`; `PMACS_REQUIRE_GPU=1 cargo test -p
+   pmacs-gpu`; `git diff --check`.
+
+(Stage 2 parser acceptance moves to the inline-math arc with the parser
+itself, per Q#LX5.)
+
+## 7. Prior art in pmacs
+
+- `docs/inline-math-framing.md` — the parent arc; this lane is its Tier 1
+  substrate, with the Tier 2 parser and Tiers 3–4 deferred.
+- `docs/multi-language-injections-framing.md` / PR #122 — the
+  `ParseTreeBundle` + `Layer` injection engine that a future
+  `(math_environment) @math` capture rides (Q#LX4).
+- PR #132 (modeline detection) — the extension→language chain
+  (`syntax.lua:452-466`) that a single `extensions` field plugs into.
+- CUDA grammar (`src/syntax.rs:919-923`, tests `:2130-2221`) — the closest
+  precedent for a multi-fragment highlights query and the grammar test
+  convention; `audit/audit-rules.scm` (`src/audit/mod.rs:76`) — the sole
+  precedent for an `include_str!`-loaded `.scm`.
diff --git a/src/highlight.rs b/src/highlight.rs
index 30d24e0..8a8914d 100644
--- a/src/highlight.rs
+++ b/src/highlight.rs
@@ -1344,4 +1344,70 @@ mod tests {
             "the injected rust `fn` keyword is painted (bold) inside the fence"
         );
     }
+
+    #[test]
+    fn latex_grid_paints_section_and_command() {
+        // Acceptance 3, paint half. The compile gate in `syntax.rs`
+        // (`latex_highlights_resolve`) proves the vendored overlay COMPILES
+        // against the grammar, but tree-sitter also compiles a pattern that
+        // uses a valid field on the wrong node and then silently never
+        // matches. This test parses a real document and asserts painted
+        // output, so a *compilable* structural drift in the sectioning or
+        // command patterns (the same class as the caught `curly_group_label`
+        // rename, but one the compile gate cannot see) fails here.
+        use crate::buffer::{Buffer, BufferId, EditOp};
+        use crate::cell::{Cell, CellSize};
+        use crate::syntax::{ParseView, SyntaxRegistry};
+
+        let reg = SyntaxRegistry::new();
+        let language = reg.language("latex").expect("latex grammar");
+        // Line 0: \section{Intro} ; line 1: \foo{bar}
+        let src = b"\\section{Intro}\n\\foo{bar}\n";
+        let mut buf = Buffer::new(BufferId::next(), "paper.tex");
+        buf.apply_edit(EditOp::Insert { pos: 0, bytes: src })
+            .unwrap();
+        let view = ParseView::new(&buf, language, "latex".to_owned());
+        let handle = view.handle();
+        let _vid = buf.attach_view(Box::new(view));
+        let mut req = handle.make_request();
+        req.injection_aliases = reg.injection_alias_snapshot();
+        let bundle = crate::syntax::run_parse(req).expect("latex parse");
+        handle.install(reg.resolve_layer_queries(&bundle));
+
+        let mut hv = SyntaxHighlightView::new(handle, reg.theme());
+        let cols = 40usize;
+        let rows = 2usize;
+        let mut backing: Vec<Cell> = vec![Cell::default(); rows * cols];
+        let mut grid = CellGrid {
+            cells: &mut backing,
+            stride: cols as u32,
+            size: CellSize::new(rows as u32, cols as u32),
+        };
+        let viewport = Viewport {
+            buffer_start: 0,
+            buffer_end: u64::MAX,
+            cell_origin: CellCoord::new(0, 0),
+            cell_size: CellSize::new(rows as u32, cols as u32),
+            gutter_w: 0,
+        };
+        let registry = buf; // keep buf alive
+        hv.render(&registry, viewport, &mut grid);
+
+        // `\foo` command_name (line 1, col 0) paints @function via the general
+        // command rule — a non-default fg, proving the reconciled query
+        // actually MATCHES, not merely compiles.
+        assert_ne!(
+            grid.get(CellCoord::new(1, 0)).style,
+            Cell::default().style,
+            "the \\foo command_name is painted (@function), not default"
+        );
+        // `Intro` section-title text (line 0, col 9) paints @keyword.control,
+        // which `default_dark` renders bold — proving the sectioning pattern
+        // structurally matches this grammar cut (would fail on a silent
+        // never-match drift).
+        assert!(
+            grid.get(CellCoord::new(0, 9)).style.bold,
+            "the \\section title text is painted @keyword.control (bold)"
+        );
+    }
 }
diff --git a/src/syntax.rs b/src/syntax.rs
index 6c91115..2f6232e 100644
--- a/src/syntax.rs
+++ b/src/syntax.rs
@@ -1093,8 +1093,32 @@ pub const BUILTIN_LANGUAGES: &[LanguageEntry] = &[
         locals_query: &[],
         injections_query: &[],
     },
+    // LaTeX / TeX. The grammar crate exports no query constants (unlike every
+    // entry above), so the highlights query is the in-repo overlay
+    // `builtin/queries/latex/highlights.scm`, `include_str!`'d as
+    // `LATEX_HIGHLIGHTS` below — the first such overlay in the tree (framing
+    // Q#LX2; the `audit-rules.scm` include is the precedent). Locals and
+    // injections are empty for v0; `(math_environment) @math` injection
+    // detection is deferred to the inline-math arc.
+    LanguageEntry {
+        name: "latex",
+        extensions: &["tex", "latex", "sty", "cls"],
+        loader: || codebook_tree_sitter_latex::LANGUAGE.into(),
+        highlights_query: &[LATEX_HIGHLIGHTS],
+        locals_query: &[],
+        injections_query: &[],
+    },
 ];
 
+/// LaTeX highlights overlay (framing Q#LX2). The chosen grammar crate
+/// (`codebook-tree-sitter-latex`) ships no query constants, so — unlike every
+/// other [`BUILTIN_LANGUAGES`] entry, which references a crate-exported
+/// `HIGHLIGHTS_QUERY` — LaTeX highlighting is driven by this vendored query,
+/// reconciled onto pmacs' recognized capture set (`crate::highlight`). The
+/// `include_str!` path mirrors the sole prior `.scm` precedent,
+/// `crate::audit`'s `audit-rules.scm`.
+const LATEX_HIGHLIGHTS: &str = include_str!("../builtin/queries/latex/highlights.scm");
+
 /// Registry that the Lua surface ([`crate::lua_bindings::install_parse`])
 /// reads to map language names to grammars and buffer ids to attached
 /// [`ParseView`] handles. Held by `Rc<...>` --- main-thread state, no
@@ -2237,6 +2261,117 @@ mod tests {
         );
     }
 
+    #[test]
+    fn builtin_languages_include_latex() {
+        // The LaTeX entry claims its four extensions and — uniquely among
+        // BUILTIN_LANGUAGES — drives highlighting from the in-repo overlay
+        // `builtin/queries/latex/highlights.scm` (`LATEX_HIGHLIGHTS`), because
+        // the grammar crate exports no query constant (framing Q#LX2).
+        let latex = BUILTIN_LANGUAGES
+            .iter()
+            .find(|l| l.name == "latex")
+            .expect("`latex` language entry must be present");
+        for ext in ["tex", "latex", "sty", "cls"] {
+            assert!(latex.extensions.contains(&ext), "`latex` claims `.{ext}`");
+        }
+        assert!(
+            latex.highlights_query.contains(&LATEX_HIGHLIGHTS),
+            "`latex` carries the in-repo highlights overlay"
+        );
+        assert!(
+            !LATEX_HIGHLIGHTS.trim().is_empty(),
+            "the vendored LaTeX highlights overlay is non-empty"
+        );
+    }
+
+    #[test]
+    fn latex_grammar_loads_and_parses() {
+        // ABI acceptance: `codebook-tree-sitter-latex` (LanguageFn over
+        // `tree-sitter-language 0.1`) must be accepted by our `tree-sitter`
+        // 0.26 core. The `verbatim` environment exercises the grammar's
+        // external scanner (`scanner.c`) — the exact surface the squatted,
+        // scanner-less `tree-sitter-latex` 0.1.0 crate lacked — so an
+        // error-free parse proves the linkable republish is wired, not a
+        // partial grammar.
+        let reg = SyntaxRegistry::new();
+        let language = reg
+            .language("latex")
+            .expect("`latex` language loads from BUILTIN_LANGUAGES");
+        let mut buf = fresh_buffer("paper.tex");
+        buf.apply_edit(EditOp::Insert {
+            pos: 0,
+            bytes: b"\\documentclass{article}\n\
+                     \\begin{document}\n\
+                     Hello $x^2$ and text.\n\
+                     \\begin{verbatim}\n\
+                     raw $ text\n\
+                     \\end{verbatim}\n\
+                     \\end{document}\n",
+        })
+        .unwrap();
+        let view = ParseView::new(&buf, language, "latex".to_owned());
+        let handle = view.handle();
+        let _vid = buf.attach_view(Box::new(view));
+        let bundle = parse_synchronously(&handle);
+        assert_eq!(
+            bundle.root_tree().root_node().kind(),
+            "source_file",
+            "LaTeX grammar roots at source_file"
+        );
+        assert!(
+            !bundle.root_tree().root_node().has_error(),
+            "LaTeX grammar parses a document with a verbatim environment \
+             (external scanner) without error"
+        );
+    }
+
+    #[test]
+    fn latex_highlights_resolve() {
+        // The vendored overlay must COMPILE against the bundled grammar —
+        // simultaneously the grammar/query node-name compatibility gate
+        // (framing Q#LX2): a query referencing a node the grammar version
+        // lacks fails here. Assert the reconciled captures are the ones pmacs
+        // recognizes, and that no upstream fall-through capture survived.
+        let reg = SyntaxRegistry::new();
+        let query = reg
+            .highlights_query("latex")
+            .expect("latex highlights compile against the grammar");
+        let names = query.capture_names();
+        for expected in ["function", "keyword", "comment"] {
+            assert!(
+                names.contains(&expected),
+                "reconciled query carries the recognized `@{expected}` capture; got {names:?}"
+            );
+        }
+        for stray in [
+            "module",
+            "label",
+            "markup.heading",
+            "markup.link",
+            "markup.math",
+        ] {
+            assert!(
+                !names.contains(&stray),
+                "reconciliation removed the fall-through `@{stray}` capture; got {names:?}"
+            );
+        }
+    }
+
+    #[test]
+    fn language_for_path_resolves_latex_extensions() {
+        // `.tex`/`.latex`/`.sty`/`.cls` all resolve to the LaTeX grammar via
+        // the same extension path as every bundled language — the single
+        // `extensions` field wires detection ahead of the LSP filetype map.
+        let reg = SyntaxRegistry::new();
+        for path in ["paper.tex", "slides.latex", "mypkg.sty", "myclass.cls"] {
+            assert_eq!(
+                reg.language_name_for_path(path).as_deref(),
+                Some("latex"),
+                "{path} resolves to latex"
+            );
+        }
+    }
+
     #[test]
     fn builtin_languages_include_bash() {
         // Regression guard: the bash entry claims the wider shell family