Custom TextMate language grammar produces no syntax highlighting in code blocks

[HugoAVaz]

Custom TextMate language grammar produces no syntax highlighting in code blocks

Description

Custom syntax highlighting for a custom language (lot) defined via styling.codeblocks.languages.custom in mint.json does not produce any token highlighting. All code blocks using the custom language render as plain unstyled monospace text -- no <span> elements with token colors are generated in the HTML output.

Configuration

mint.json (relevant section):

"styling": {
  "codeblocks": {
    "theme": "css-variables",
    "languages": {
      "custom": ["/languages/lot.json"]
    }
  }
}

CSS variables defined in global.css:

:root {
  --mint-color-background: #1a1a2e;
  --mint-color-text: #e4e4e7;
  --mint-token-keyword: #c792ea;
  --mint-token-string: #c3e88d;
  --mint-token-constant: #f78c6c;
  --mint-token-comment: #676e95;
  --mint-token-function: #82aaff;
  --mint-token-parameter: #ffcb6b;
  --mint-token-punctuation: #89ddff;
  --mint-token-string-expression: #c3e88d;
  --mint-token-link: #6366f1;
}

Grammar file (/languages/lot.json) -- valid TextMate grammar JSON:

{
  "$schema": "https://raw.githubusercontent.com/martinring/tmlanguage/master/tmlanguage.json",
  "name": "lot",
  "scopeName": "source.lot",
  "fileTypes": ["lot", "lotnb"],
  "patterns": [
    { "include": "#comments" },
    { "include": "#strings" },
    { "include": "#numbers" },
    { "include": "#keywords" },
    { "include": "#types" },
    { "include": "#constants" },
    { "include": "#variables" },
    { "include": "#operators" }
  ],
  "repository": {
    "comments": {
      "patterns": [
        { "name": "comment.line.double-dash", "match": "--.*$" },
        { "name": "comment.line.double-slash", "match": "//.*$" }
      ]
    },
    "strings": {
      "patterns": [
        {
          "name": "string.quoted.double",
          "begin": "\"",
          "end": "\"",
          "patterns": [{ "name": "constant.character.escape", "match": "\\\\." }]
        }
      ]
    },
    "numbers": {
      "patterns": [
        { "name": "constant.numeric", "match": "\\b[0-9]+\\.?[0-9]*\\b" }
      ]
    },
    "keywords": {
      "patterns": [
        {
          "name": "keyword.control",
          "match": "\\b(DEFINE|ACTION|MODEL|ROUTE|RULE|ON|DO|EVERY|IF|THEN|ELSE|WITH|AS|FROM|TO|IN|USING|FOR|RETURN|INPUT|OUTPUT|BETWEEN|AND|OR|NOT|DELETE|START|STOP)\\b"
        },
        {
          "name": "keyword.other",
          "match": "\\b(TOPIC|PUBLISH|KEEP|GET|SET|ADD|TRIGGER|CALL|PYTHON|MCP|JSON|POSITION|RANDOM|REPLACE|FILTER|TRIM|SPLIT|CSV|REGEX|SEPARATOR|HEADERS|PRESENT|NONE|MAPPING|EVENT|SOURCE_TOPIC|DESTINATION_TOPIC|DIRECTION|COLLAPSED|ENV|SECRET)\\b"
        }
      ]
    },
    "types": {
      "patterns": [
        { "name": "storage.type", "match": "\\b(STRING|INT|DOUBLE|BOOL|OBJECT|ARRAY|INTEGER|BOOLEAN|FLOAT)\\b" },
        { "name": "entity.name.class", "match": "\\b(MQTT_BRIDGE|MQTT_CLUSTER|OPENSEARCH|EMAIL|CRATEDB|POSTGRESQL|MONGODB|REST_API|MODBUS_TCP|MODBUS_SERIAL|SIEMENS_S7|OPCUA|ADS|ALLEN_BRADLEY|ETHERNETIP|FINS)\\b" }
      ]
    },
    "constants": {
      "patterns": [
        { "name": "constant.language", "match": "\\b(PAYLOAD|TIMESTAMP|EMPTY|TRUE|FALSE|true|false|UTC|UNIX|UUID|GUID|ULID)\\b" },
        { "name": "constant.other", "match": "\\b(SECONDS?|MINUTES?|HOURS?|DAYS?|WEEKS?)\\b" }
      ]
    },
    "variables": {
      "patterns": [
        { "name": "variable.other", "match": "\\{[a-zA-Z_][a-zA-Z0-9_\\.]*\\}" }
      ]
    },
    "operators": {
      "patterns": [
        { "name": "keyword.operator", "match": "(==|!=|>=|<=|>|<|\\+|\\-|\\*|/|%)" }
      ]
    }
  }
}

Usage in Markdown

```lot
DEFINE ACTION Heartbeat
ON EVERY 5 SECONDS DO
    PUBLISH TOPIC "system/alive" WITH "ok"
```

Expected behavior

Keywords like DEFINE, ACTION, ON, EVERY, DO, PUBLISH, TOPIC, WITH should render with --mint-token-keyword color. Strings like "system/alive" should render with --mint-token-string color. Each token should be wrapped in a <span> with the appropriate CSS variable applied.

Actual behavior

The entire code block renders as plain text in a single color. No token <span> elements are generated in the HTML output. The custom grammar is not being loaded by Shiki during the build -- the language identifier lot is treated as unrecognized and falls back to plain text.

Screenshots

What we see (no highlighting):

All tokens are the same grey/white color in the rendered code block. No differentiation between keywords, strings, constants, or comments.

Live example

https://docs.coreflux.org/lot-language/introduction -- see the "Hello World" code blocks.

Steps to reproduce

1. Create a valid TextMate grammar JSON file at /languages/lot.json
2. Reference it in mint.json under styling.codeblocks.languages.custom
3. Set styling.codeblocks.theme to "css-variables"
4. Define --mint-token-* CSS variables in global.css
5. Use ```lot code fences in any markdown page
6. Deploy -- code blocks render without any syntax highlighting

Environment

• Configuration file: mint.json (not yet migrated to docs.json)
• Deployment: Mintlify GitHub integration
• The grammar works correctly in VS Code with the same TextMate JSON, confirming it is valid