Specify the template language grammar

[Matographo]

Summary

Define the concrete grammar for variables, expressions, control flow, includes, comments, inline mode, and block mode so implementation can start from a stable language contract.

Why

The lexer, parser, evaluator, and renderer cannot be implemented confidently until the language surface is frozen enough to remove ambiguity.

Deliverables

• Stable draft grammar for expressions and directives
• Defined syntax for conditionals, loops, includes, and comments
• Safe missing-value semantics for chained access
• Clear separation between inline and block constructs

Acceptance Criteria

• Grammar covers expressions, directives, includes, and comments
• Safe missing-value propagation is explicitly specified
• Inline vs block semantics are documented
• Open spec points are clearly identified

Dependencies

• None

Related Docs

• LANGUAGE_SPEC.md
• REQUIREMENTS.md