parser-ast-implementation

name	parser-ast-implementation
description	Implement or refactor the Talqor lexer, parser, and AST from the approved grammar while preserving spans, diagnostics, and regression coverage.
argument-hint	["frontend-task"]
allowed-tools	Read, Grep, Glob, Edit, Write, MultiEdit, Bash
context	fork
agent	parser-frontend-engineer
effort	high

Parser and AST Implementation

Implement $ARGUMENTS from spec to code with zero silent grammar drift.

Required workflow

1. Read the relevant grammar and any ADRs before editing code.
2. Identify the exact frontend layers touched:
   • lexer
   • parser
   • CST / parse tree
   • AST
   • diagnostics
   • test harness
3. Translate grammar rules into explicit code constructs.
4. Preserve or improve:
   • source spans
   • recovery behavior
   • error messages
   • AST clarity
5. Add or update:
   • positive parse tests
   • negative parse tests
   • AST golden or structural tests if used by the repo
6. If the grammar is unclear, stop and note the ambiguity instead of inventing a rule.

Supporting files

• frontend-checklist.md
• test-cases.md

Final output

Summarize:

• spec rules used
• files changed
• invariants preserved
• tests added
• unresolved grammar ambiguity