feat(campaign): govern attachment reuse

webui/src/features/campaigns/AttachmentsDataPage.tsx

@@ -58,6 +58,9 @@ export default function AttachmentsDataPage({ settings, campaignId }: {settings:
   const basePaths = useMemo(() => normalizeAttachmentBasePaths(attachments.base_paths, attachments), [attachments]);
   const globalRules = useMemo(() => normalizeAttachmentRules(attachments.global), [attachments.global]);
   const zipConfig = useMemo(() => normalizeAttachmentZipCollection(attachments.zip), [attachments.zip]);
+  const reusePolicy = asRecord(attachments.reuse_policy);
+  const reuseAction = ["allow", "warn", "review", "block"].includes(String(reusePolicy.action)) ? String(reusePolicy.action) : "allow";
+  const reuseAllowance = ["same_recipient", "same_message"].includes(String(reusePolicy.allow_within)) ? String(reusePolicy.allow_within) : "none";
   const residualFiles = asRecord(attachments.residual_files);
   const residualMode = ["report", "attach"].includes(String(residualFiles.mode)) ? String(residualFiles.mode) : "none";
   const residualRecipient = asRecord(residualFiles.recipient);
@@ -113,6 +116,16 @@ export default function AttachmentsDataPage({ settings, campaignId }: {settings:
     });
   }
 
+  function patchReusePolicy(next: Record<string, unknown>) {
+    if (locked) return;
+    patch(["attachments", "reuse_policy"], {
+      action: "allow",
+      allow_within: "none",
+      ...reusePolicy,
+      ...next
+    });
+  }
+
   function patchBasePath(index: number, patch: Partial<AttachmentBasePath>) {
     patchBasePaths(basePaths.map((basePath, currentIndex) => currentIndex === index ? { ...basePath, ...patch } : basePath));
   }
@@ -306,6 +319,29 @@ export default function AttachmentsDataPage({ settings, campaignId }: {settings:
             </div>
           </Card>
 
+          <Card title="Attachment reuse policy" collapsible>
+            <div className="campaign-residual-file-form">
+              <FormField label="Duplicate-file action" help="Applied when the same resolved source file appears more than once outside the configured allowance.">
+                <select value={reuseAction} disabled={locked} onChange={(event) => patchReusePolicy({ action: event.target.value })}>
+                  <option value="allow">Allow and record</option>
+                  <option value="warn">Allow with warning</option>
+                  <option value="review">Require explicit review</option>
+                  <option value="block">Block delivery</option>
+                </select>
+              </FormField>
+              <FormField label="Allowed reuse boundary" help="A boundary is an exception to the selected action. No exception applies the action to every repeated use.">
+                <select value={reuseAllowance} disabled={locked} onChange={(event) => patchReusePolicy({ allow_within: event.target.value })}>
+                  <option value="none">No exception</option>
+                  <option value="same_recipient">Within the same recipient</option>
+                  <option value="same_message">Within the same built message</option>
+                </select>
+              </FormField>
+            </div>
+            <DismissibleAlert tone={reuseAction === "block" ? "warning" : "info"} dismissible={false} compact>
+              Every repeated-file finding is retained in the build protocol. Review requires a reason bound to the exact build; Block prevents affected messages from being queued.
+            </DismissibleAlert>
+          </Card>
+
           <Card title="Unassigned file disposition" collapsible>
             <div className="campaign-residual-file-form">
               <FormField label="Action" help="Only sources with Unsent enabled are inspected. The existing warning policy remains active when no disposition is selected.">

webui/src/features/campaigns/ReviewSendPage.tsx

@@ -158,6 +158,9 @@ export default function ReviewSendPage({
   );
   const validation = asRecord(version?.validation_summary);
   const build = asRecord(version?.build_summary);
+  const attachmentReuse = asRecord(build.attachment_reuse);
+  const attachmentReusePolicy = asRecord(attachmentReuse.policy);
+  const attachmentReuseFindings = asArray(attachmentReuse.findings).map(asRecord);
   const residualFileDisposition = asRecord(build.residual_file_disposition);
   const residualFileRecipient = asRecord(residualFileDisposition.recipient);
   const printOutput = asRecord(build.print_output);
@@ -1504,6 +1507,29 @@ export default function ReviewSendPage({
                 </DescriptionList>
               </div>
             )}
+            {hasBuild && Object.keys(attachmentReuse).length > 0 && (
+              <div className="review-flow-data-section" data-attachment-reuse-policy>
+                <h3>Attachment reuse policy</h3>
+                <DescriptionList variant="inline">
+                  <div><dt>Action</dt><dd>{humanize(String(attachmentReusePolicy.action ?? "allow"))}</dd></div>
+                  <div><dt>Allowed boundary</dt><dd>{humanize(String(attachmentReusePolicy.allow_within ?? "none"))}</dd></div>
+                  <div><dt>Repeated files</dt><dd>{String(attachmentReuse.duplicate_file_count ?? 0)}</dd></div>
+                  <div><dt>Allowed</dt><dd>{String(attachmentReuse.allowed_file_count ?? 0)}</dd></div>
+                  <div><dt>Policy findings</dt><dd>{String(attachmentReuse.violation_file_count ?? 0)}</dd></div>
+                  <div><dt>Affected messages</dt><dd>{String(attachmentReuse.affected_message_count ?? 0)}</dd></div>
+                </DescriptionList>
+                {attachmentReuseFindings.length > 0 && (
+                  <ul className="small-note">
+                    {attachmentReuseFindings.slice(0, 10).map((finding) => (
+                      <li key={String(finding.file_fingerprint)}>
+                        {String(finding.file_name ?? "Attachment")} · {String(finding.use_count ?? 0)} uses · {humanize(String(finding.disposition ?? "allowed"))}
+                      </li>
+                    ))}
+                  </ul>
+                )}
+                {attachmentReuseFindings.length > 10 && <p className="muted small-note">Showing 10 of {attachmentReuseFindings.length} repeated files.</p>}
+              </div>
+            )}
             {getText(printOutput, "render_id") && (
               <div className="review-flow-data-section">
                 <div className="page-heading split">

webui/src/features/campaigns/utils/draftEditor.ts

@@ -28,6 +28,10 @@ export function ensureCampaignDraft(version: CampaignVersionDetail | null): Reco
     allow_individual: false,
     send_without_attachments: true,
     send_without_attachments_behavior: "continue",
+    reuse_policy: {
+      action: "allow",
+      allow_within: "none"
+    },
     global: [],
     residual_files: {
       mode: "none",

webui/tests/review-workflow-guidance-ui-structure.test.mjs

@@ -6,6 +6,7 @@ import { fileURLToPath } from "node:url";
 const here = dirname(fileURLToPath(import.meta.url));
 const guidance = readFileSync(resolve(here, "../src/features/campaigns/review/ReviewWorkflowGuidance.tsx"), "utf8");
 const page = readFileSync(resolve(here, "../src/features/campaigns/ReviewSendPage.tsx"), "utf8");
+const attachmentsPage = readFileSync(resolve(here, "../src/features/campaigns/AttachmentsDataPage.tsx"), "utf8");
 
 assert.match(guidance, /<ActionBlockerHint/);
 assert.match(guidance, /<GuidedReviewList/);
@@ -23,5 +24,15 @@ assert.match(page, /data-residual-file-policy/);
 assert.match(page, /build\.residual_file_disposition/);
 assert.match(page, /residual_file_count/);
 assert.match(page, /watched_source_count/);
+assert.match(page, /data-attachment-reuse-policy/);
+assert.match(page, /build\.attachment_reuse/);
+assert.match(page, /attachmentReusePolicy\.allow_within/);
+assert.match(attachmentsPage, /patch\(\["attachments", "reuse_policy"\]/);
+for (const action of ["allow", "warn", "review", "block"]) {
+  assert.match(attachmentsPage, new RegExp(`<option value="${action}">`));
+}
+for (const allowance of ["none", "same_recipient", "same_message"]) {
+  assert.match(attachmentsPage, new RegExp(`<option value="${allowance}">`));
+}
 assert.doesNotMatch(page, /blocked_or_failed_message_s_must_be_resolved_bef/);
 assert.doesNotMatch(page, /resolve_the_blocking_entries_then_validate_again/);