feat: add question-render fenced markers and Claude transformer

[Rohan-1920]

🚀 PR: Add Claude-native AskUserQuestion Rendering Pipeline

Overview

• Adds a non-invasive transformation layer for Claude Code integration in spec-kit
• Converts Markdown question tables into structured AskUserQuestion payloads
• Only applies to Claude integration — all other agents remain unchanged
• No changes to CLI behavior or core command logic

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Changes

Templates

• Added fenced markers to isolate question-rendering blocks in:

  • templates/commands/clarify.md
  • templates/commands/checklist.md

• Markers used:

  • <!-- speckit:question-render:begin -->
  • <!-- speckit:question-render:end -->

• No changes to existing logic or structure

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Core Module

New file: src/specify_cli/core/question_transformer.py

• Detects fenced question blocks

• Parses:

  • Option | Description (clarify)
  • Option | Candidate | Why It Matters (checklist)

• Converts into AskUserQuestion payload

• Extra behavior:

  • Recommended option prioritized (clarify)
  • Adds fallback option: “Provide my own short answer (≤10 words)”
  • Safe handling for duplicates
  • Returns original content unchanged when no markers exist

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Claude Integration

• Updated src/specify_cli/integrations/claude/__init__.py
• Transformation applied only for Claude Code
• Other integrations remain byte-identical

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Agents Fix

• Updated src/specify_cli/agents.py
• Fixed {SCRIPT} / {AGENT_SCRIPT} resolution logic
• Improved cross-platform compatibility

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Tests

Unit Tests

• tests/test_question_transformer.py
  • 31 tests covering parsing, edge cases, and mapping logic

Integration Tests

• tests/integrations/test_integration_claude.py
  • 8 tests covering:
    • AskUserQuestion generation
    • clarify & checklist flows
    • no Markdown leakage in Claude output
    • non-Claude agents remain unchanged

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Backward Compatibility

• Non-Claude agents are fully unaffected
• HTML comment markers are invisible to all other systems
• No CLI flags or config changes introduced
• No changes to existing command behavior

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Result

• Before: Markdown table-based questions with manual selection
• After (Claude only): Native AskUserQuestion UI with structured selection and fallback option