feat(06-02): create exporter module for markdown export

- export_discussion() formats discussion with rounds and messages
- export_project() creates full project export with header
- _format_consensus() helper for consensus section formatting
- Follows SPEC.md markdown format

src/moai/core/exporter.py

@@ -0,0 +1,117 @@
+"""Markdown export functionality for MoAI discussions and projects.
+
+Exports discussions and projects to shareable markdown documents following
+the SPEC format with sections for initial responses, rounds, and consensus.
+"""
+
+from datetime import datetime
+
+from moai.core.models import Consensus, Discussion, Project, RoundType
+
+
+def _format_consensus(consensus: Consensus | None) -> str:
+    """Format consensus section as markdown.
+
+    Args:
+        consensus: The Consensus object to format, or None.
+
+    Returns:
+        Formatted markdown string for consensus, or empty string if none.
+    """
+    if consensus is None:
+        return ""
+
+    lines = ["### Consensus"]
+
+    if consensus.agreements:
+        lines.append("**Agreements:**")
+        for agreement in consensus.agreements:
+            lines.append(f"- {agreement}")
+        lines.append("")
+
+    if consensus.disagreements:
+        lines.append("**Disagreements:**")
+        for disagreement in consensus.disagreements:
+            topic = disagreement.get("topic", "Unknown topic")
+            positions = disagreement.get("positions", {})
+            lines.append(f"- **{topic}:**")
+            for model, position in positions.items():
+                lines.append(f"  - {model}: {position}")
+        lines.append("")
+
+    return "\n".join(lines)
+
+
+def export_discussion(discussion: Discussion) -> str:
+    """Export a discussion as markdown.
+
+    Args:
+        discussion: The Discussion object to export (with rounds/messages loaded).
+
+    Returns:
+        Markdown string formatted according to SPEC.
+    """
+    lines = [f"## Discussion: {discussion.question}", ""]
+
+    # Group messages by round
+    sorted_rounds = sorted(discussion.rounds, key=lambda r: r.round_number)
+
+    for round_ in sorted_rounds:
+        # Label round type appropriately
+        if round_.type == RoundType.PARALLEL:
+            lines.append("### Initial Responses (Open)")
+        else:
+            lines.append(f"### Round {round_.round_number}")
+        lines.append("")
+
+        # Format each message
+        sorted_messages = sorted(round_.messages, key=lambda m: m.timestamp)
+        for message in sorted_messages:
+            model_name = message.model.capitalize()
+            lines.append(f"**{model_name}:**")
+            # Quote the response content
+            for content_line in message.content.split("\n"):
+                lines.append(f"> {content_line}")
+            lines.append("")
+
+    # Add consensus section if exists
+    consensus_md = _format_consensus(discussion.consensus)
+    if consensus_md:
+        lines.append(consensus_md)
+
+    return "\n".join(lines)
+
+
+def export_project(project: Project, discussions: list[Discussion]) -> str:
+    """Export a project and its discussions as markdown.
+
+    Args:
+        project: The Project object to export.
+        discussions: List of Discussion objects (with rounds/messages loaded).
+
+    Returns:
+        Full markdown string for the project export.
+    """
+    # Header section
+    date_str = datetime.now().strftime("%Y-%m-%d")
+    models_str = ", ".join(m.capitalize() for m in project.models) if project.models else "None"
+
+    lines = [
+        f"# {project.name}",
+        "",
+        f"**Date:** {date_str}",
+        f"**Models:** {models_str}",
+        f"**Discussions:** {len(discussions)}",
+        "",
+        "---",
+        "",
+    ]
+
+    # Add each discussion
+    for i, discussion in enumerate(discussions):
+        if i > 0:
+            lines.append("---")
+            lines.append("")
+        lines.append(export_discussion(discussion))
+
+    return "\n".join(lines)