feat(campaign): record unmatched file disposition

src/govoplan_campaign/backend/messages/builder.py

@@ -1103,6 +1103,39 @@ def _build_residual_file_message(
     )
 
 
+def _residual_file_disposition_evidence(
+    *,
+    config: CampaignConfig,
+    residual_groups: list[_ResidualFileGroup],
+) -> dict[str, object]:
+    disposition = config.attachments.residual_files
+    behavior = config.validation_policy.unsent_attachment_files.value
+    if disposition.mode == ResidualFileMode.REPORT:
+        action = "route_report"
+    elif disposition.mode == ResidualFileMode.ATTACH:
+        action = "route_with_files"
+    elif behavior == Behavior.BLOCK.value:
+        action = "block"
+    elif behavior in {Behavior.CONTINUE.value, Behavior.DROP.value}:
+        action = "ignore"
+    else:
+        action = "review"
+    recipient = (
+        disposition.recipient.model_dump(mode="json", by_alias=True)
+        if disposition.recipient is not None
+        else None
+    )
+    return {
+        "contract_version": "1",
+        "action": action,
+        "routing_mode": disposition.mode.value,
+        "validation_behavior": behavior,
+        "watched_source_count": len(residual_groups),
+        "residual_file_count": sum(len(group.files) for group in residual_groups),
+        "recipient": recipient,
+    }
+
+
 def _apply_campaign_level_issues(built_messages: list[BuiltMessage], issues: list[MessageIssue]) -> None:
     if not issues:
         return
@@ -1183,5 +1216,9 @@ def build_campaign_messages(
             duration_ms=(time.perf_counter() - started) * 1000,
             rules_resolved=rules_resolved,
         ),
+        residual_file_disposition=_residual_file_disposition_evidence(
+            config=config,
+            residual_groups=residual_groups,
+        ),
     )
     return CampaignBuildResult(report=report, built_messages=built_messages)