feat(harness): tht session documents --json read command

harness/tht/session/store.py

@@ -164,3 +164,27 @@ def delete_session(session_id: str, sessions_root: Path) -> None:
     """Hard-delete the session directory. SessionError if it does not exist."""
     load_session(session_id, sessions_root)  # raises SessionError if absent
     shutil.rmtree(sessions_root / session_id)
+
+
+def build_documents(manifest: SessionManifest, session_dir: Path) -> list[dict]:
+    """Ordered, read-only document bundle for the UI panel. Only documents that exist
+    on disk are returned. CTE artifacts (F6) are intentionally excluded (intermediate)."""
+    docs: list[dict] = [{
+        "phase": "—", "key": "question", "title": "Domanda originale",
+        "format": "text", "content": manifest.question,
+    }]
+    spec = [
+        ("question.md", "F3", "revised_question", "Domanda rivista", "markdown"),
+        ("schema_linking.json", "F4", "schema_linking", "Schema linking", "schema-linking"),
+        ("sql_final.sql", "F7", "sql", "SQL finale", "sql"),
+        ("validation_report.md", "finalize", "validation_report", "Report di validazione", "markdown"),
+        ("review_decisions.jsonl", "—", "decisions", "Decisioni", "decisions"),
+    ]
+    for filename, phase, key, title, fmt in spec:
+        path = session_dir / filename
+        if path.exists():
+            docs.append({
+                "phase": phase, "key": key, "title": title,
+                "format": fmt, "content": path.read_text(),
+            })
+    return docs