{
  "about": "A tool description's or a prompt text's `{{variables}}` filled in (`vars`): a value replaces its variable where it stands; a line that is nothing but a bullet and a variable (`- {{name}}`) disappears when the value is empty or blank; a variable with no value at all is an error naming every one missing (`missing`, sorted). Applied to a tool's description and to every `description` inside its parameters. LLeMbas: services/harness_spec.py fill; CLI: prompt/fill.ts fillPrompt.",
  "cases": [
    {
      "text": "Read a page{{files}}",
      "vars": {
        "files": "."
      },
      "expect": {
        "text": "Read a page."
      }
    },
    {
      "text": "Kept across sessions{{kept}}.",
      "vars": {
        "kept": ""
      },
      "expect": {
        "text": "Kept across sessions."
      }
    },
    {
      "text": "- create: one.\n- {{files}}\n- delete: two.",
      "vars": {
        "files": ""
      },
      "expect": {
        "text": "- create: one.\n- delete: two."
      }
    },
    {
      "text": "- create: one.\n- {{files}}\n- delete: two.",
      "vars": {
        "files": "   "
      },
      "expect": {
        "text": "- create: one.\n- delete: two."
      }
    },
    {
      "text": "- create: one.\n  * {{files}}\n- delete: two.",
      "vars": {
        "files": "write_file."
      },
      "expect": {
        "text": "- create: one.\n  * write_file.\n- delete: two."
      }
    },
    {
      "text": "A {{a}} and a {{b}} and {{a}} again",
      "vars": {
        "a": "x",
        "b": "y"
      },
      "expect": {
        "text": "A x and a y and x again"
      }
    },
    {
      "text": "Only {{a}} and {{c}} and {{b}}",
      "vars": {
        "a": "x"
      },
      "expect": {
        "missing": [
          "b",
          "c"
        ]
      }
    },
    {
      "text": "No variables at all.",
      "vars": {},
      "expect": {
        "text": "No variables at all."
      }
    },
    {
      "text": "- not only {{a}} on this line",
      "vars": {
        "a": ""
      },
      "expect": {
        "text": "- not only  on this line"
      }
    }
  ]
}