feat(documenso-phase-4): recipient configurator + field placement UI

Phase 4 lands the visual half of the Documenso build — the upload-
for-signing dialog the Contract + Reservation tabs hand off to. Four
files of new code; the existing tab placeholders point at it.

Files added:
- lib/services/document-field-detector.ts — Phase 4c auto-detect
  scanner. Uses pdfjs-dist to extract per-page text + positions, then
  matches anchor patterns (Signature, Date, Initials, Email, Name,
  underscore-runs) and produces percent-coordinate DetectedField
  rows. Recipient label inference walks ±100pt of each match for
  Buyer/Seller/Client/Witness/Notary keywords. Returns [] when the
  PDF is image-only; UI falls back to manual placement without an
  error. 6 unit tests pin the matching + coordinate math.

- app/api/v1/documents/auto-detect-fields/route.ts — multipart POST
  endpoint that delegates to detectFields(). Permission-gated by
  documents.send_for_signing.

- app/api/v1/documents/signing-defaults/route.ts — GET endpoint that
  surfaces just the per-port developer + approver display name/email
  + sendMode flag. No secrets exposed; lets the dialog prefill the
  recipient configurator without an admin-scoped settings read.

- components/documents/upload-for-signing-dialog.tsx — the Phase 4
  UI. Three-step state machine inside a single Dialog:
    1. select-file:  drop/click PDF picker + title input
    2. configure-recipients: client + developer + approver prefilled,
       rep can add/remove/reorder + change role (SIGNER/APPROVER/CC)
    3. place-fields: react-pdf renders the source PDF; auto-detect
       runs in the background on file load and seeds the overlay;
       rep places, drags, resizes, deletes, reassigns fields via the
       palette + side panel. Native DOM drag (no dnd-kit dependency
       added — the coordinate math stays obvious).
  Send fires POST /api/v1/interests/[id]/upload-for-signing (Phase 3
  service); success toast reflects port sendMode (auto fires the
  invite immediately, manual leaves it for the rep).

Files modified:
- components/interests/interest-contract-tab.tsx + reservation-tab.tsx:
  swap the ComingSoonDialog placeholder for the real
  UploadForSigningDialog with the matching documentType prop. The
  placeholder ComingSoonDialog helper is deleted from both.

- scripts/tsc-staged.mjs: pull src/types/**/*.d.ts into the temp
  staged-only tsconfig so side-effect CSS imports (e.g.
  react-pdf/dist/Page/AnnotationLayer.css) resolve via the existing
  declare-module shim. Without this fix the staged compile reports
  TS2882 even though the full tsc --noEmit pass passes.

Design choices noted in code comments:
- Native drag over dnd-kit: the field overlay's percent-based
  coordinate math is short enough that adding a drag library adds
  complexity without saving lines.
- Auto-detect on file-load (not on demand): runs immediately so the
  rep doesn't have to click a second button — empty result drops
  back to manual placement silently.
- Per-recipient color swatches indexed by signingOrder.
- Recipient seed via useMemo + user-event handler instead of
  useEffect → setRecipients (Wave 3 set-state-in-effect avoidance).

Server-side, Phase 3 plumbing handles the rest: tenant guard, magic-
byte verify, Documenso round-trip with per-port v1/v2 routing,
recipient signingToken capture for Phase 2 webhook cascade, auto-
send when port.sendMode === 'auto'.

Tests: 1334 → 1340 ✅ (6 new for the detector); tsc clean.

Deferred polish (Phase 6):
- Per-field metadata side panel for DROPDOWN/RADIO option lists
- Pinch-zoom + zoom-out controls on the field-placement canvas
- Recipient drag-reorder via dnd-kit
- Required toggle per field

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/tsc-staged.mjs

@@ -36,6 +36,13 @@ const tmpConfig = join(tmpDir, 'tsconfig.json');
 
 const relFiles = files.map((f) => relative(tmpDir, resolve(cwd, f)));
 
+// Pull in the project's ambient .d.ts files (css module shim,
+// react-pdf JSX augment, etc.) so side-effect imports like
+// `import 'react-pdf/dist/Page/AnnotationLayer.css'` resolve under the
+// staged-only compile. Without this, `include: []` would shut out
+// everything in src/types/ and tsc reports TS2882 for any CSS import.
+const ambientTypesGlob = relative(tmpDir, join(cwd, 'src/types')) + '/**/*.d.ts';
+
 writeFileSync(
   tmpConfig,
   JSON.stringify(
@@ -50,7 +57,7 @@ writeFileSync(
         types: ['node', 'react', 'react-dom'],
       },
       files: relFiles,
-      include: [],
+      include: [ambientTypesGlob],
     },
     null,
     2,

src/app/api/v1/documents/auto-detect-fields/route.ts

@@ -0,0 +1,50 @@
+import { NextResponse } from 'next/server';
+
+import { withAuth, withPermission } from '@/lib/api/helpers';
+import { errorResponse, ValidationError } from '@/lib/errors';
+import { detectFields } from '@/lib/services/document-field-detector';
+import { isPdfMagic } from '@/lib/services/berth-pdf-parser';
+
+/**
+ * Phase 4 — Auto-detect anchor scanner endpoint.
+ *
+ * POST `/api/v1/documents/auto-detect-fields`
+ *
+ * Body: multipart/form-data
+ *   - file: the source PDF the rep just uploaded
+ *
+ * Returns: `{ data: { fields: DetectedField[] } }` — seed state for the
+ * drag-drop overlay. Empty array when the PDF has no extractable text
+ * (image-only scan) — the dialog falls back to manual placement
+ * without an error toast.
+ *
+ * Permission: documents.send_for_signing — the only flow that calls
+ * this endpoint is the upload-for-signing dialog, which already
+ * requires that bit. Reusing it here means a custom role with the
+ * upload bit but no send bit can't dry-run the detector to pull
+ * structural metadata out of a contract before sending.
+ */
+const MAX_PDF_BYTES = 50 * 1024 * 1024;
+
+export const POST = withAuth(
+  withPermission('documents', 'send_for_signing', async (req) => {
+    try {
+      const form = await req.formData();
+      const file = form.get('file');
+      if (!file || !(file instanceof File)) {
+        throw new ValidationError('Missing file');
+      }
+      if (file.size > MAX_PDF_BYTES) {
+        throw new ValidationError(`File exceeds ${MAX_PDF_BYTES / 1024 / 1024} MB cap`);
+      }
+      const buffer = Buffer.from(await file.arrayBuffer());
+      if (!isPdfMagic(buffer)) {
+        throw new ValidationError('Uploaded file is not a PDF');
+      }
+      const fields = await detectFields(buffer);
+      return NextResponse.json({ data: { fields } });
+    } catch (error) {
+      return errorResponse(error);
+    }
+  }),
+);

src/app/api/v1/documents/signing-defaults/route.ts

@@ -0,0 +1,43 @@
+import { NextResponse } from 'next/server';
+
+import { withAuth, withPermission } from '@/lib/api/helpers';
+import { errorResponse } from '@/lib/errors';
+import { getPortDocumensoConfig } from '@/lib/services/port-config';
+
+/**
+ * GET `/api/v1/documents/signing-defaults`
+ *
+ * Returns the per-port developer + approver defaults the
+ * UploadForSigningDialog uses to prefill the recipient configurator.
+ * No secrets are exposed — just the display name, email, and the
+ * sendMode flag so the UI can show the right CTA copy ("Send now" vs
+ * "Save draft, send manually").
+ *
+ * Permission: documents.send_for_signing — the only caller is the
+ * upload-for-signing dialog which already requires this permission to
+ * complete the flow.
+ */
+export const GET = withAuth(
+  withPermission('documents', 'send_for_signing', async (_req, ctx) => {
+    try {
+      const cfg = await getPortDocumensoConfig(ctx.portId);
+      return NextResponse.json({
+        data: {
+          developer: {
+            name: cfg.developerName ?? '',
+            email: cfg.developerEmail ?? '',
+            label: cfg.developerLabel ?? 'Developer',
+          },
+          approver: {
+            name: cfg.approverName ?? '',
+            email: cfg.approverEmail ?? '',
+            label: cfg.approverLabel ?? 'Approver',
+          },
+          sendMode: cfg.sendMode,
+        },
+      });
+    } catch (error) {
+      return errorResponse(error);
+    }
+  }),
+);

src/components/interests/interest-contract-tab.tsx

@@ -20,6 +20,7 @@ import { Button } from '@/components/ui/button';
 import { Skeleton } from '@/components/ui/skeleton';
 import { ExternalEoiUploadDialog } from '@/components/interests/external-eoi-upload-dialog';
 import { SigningProgress } from '@/components/documents/signing-progress';
+import { UploadForSigningDialog } from '@/components/documents/upload-for-signing-dialog';
 import { apiFetch } from '@/lib/api/client';
 import { toastError } from '@/lib/api/toast-error';
 import { useConfirmation } from '@/hooks/use-confirmation';
@@ -168,16 +169,16 @@ export function InterestContractTab({ interestId, clientId: _clientId }: Interes
         />
       )}
 
-      {/* Upload-for-Documenso-signing dialog placeholder. The real
-          dialog (PDF picker + recipient configurator + send button)
-          is part of the larger custom-doc-upload service that's a
-          follow-up. For now show a friendly "coming soon" card. */}
+      {/* Phase 4 — upload-for-Documenso-signing dialog. Multi-step
+          (file → recipients → fields → send) backed by the Phase 3
+          service. Auto-detect runs after the file lands; rep can
+          tweak placements before sending. */}
       {uploadForSigningOpen && (
-        <ComingSoonDialog
+        <UploadForSigningDialog
           open={uploadForSigningOpen}
           onOpenChange={setUploadForSigningOpen}
-          title="Send contract for signing"
-          body="Upload-and-send-via-Documenso for contracts is being built. For now, draft the contract externally, get it signed via paper or another tool, then upload the signed copy here."
+          interestId={interestId}
+          documentType="contract"
         />
       )}
     </div>
@@ -381,44 +382,3 @@ function StatusBadge({ status }: { status: DocumentRow['status'] }) {
     </Badge>
   );
 }
-
-/**
- * Placeholder for the upload-for-Documenso-signing flow until the
- * full upload + recipient + field-placement service is shipped.
- * Intentional dead-end so reps know the path exists rather than
- * misclicking and getting confusing behaviour.
- */
-function ComingSoonDialog({
-  open,
-  onOpenChange,
-  title,
-  body,
-}: {
-  open: boolean;
-  onOpenChange: (next: boolean) => void;
-  title: string;
-  body: string;
-}) {
-  if (!open) return null;
-  return (
-    <div
-      role="dialog"
-      aria-modal="true"
-      className="fixed inset-0 z-50 flex items-center justify-center bg-black/40 p-4"
-      onClick={() => onOpenChange(false)}
-    >
-      <div
-        className="max-w-md rounded-lg border bg-background p-6 shadow-lg"
-        onClick={(e) => e.stopPropagation()}
-      >
-        <h3 className="text-base font-semibold text-foreground">{title}</h3>
-        <p className="mt-2 text-sm text-muted-foreground">{body}</p>
-        <div className="mt-4 flex justify-end">
-          <Button onClick={() => onOpenChange(false)} size="sm" variant="outline">
-            Got it
-          </Button>
-        </div>
-      </div>
-    </div>
-  );
-}

src/components/interests/interest-reservation-tab.tsx

@@ -20,6 +20,7 @@ import { Button } from '@/components/ui/button';
 import { Skeleton } from '@/components/ui/skeleton';
 import { ExternalEoiUploadDialog } from '@/components/interests/external-eoi-upload-dialog';
 import { SigningProgress } from '@/components/documents/signing-progress';
+import { UploadForSigningDialog } from '@/components/documents/upload-for-signing-dialog';
 import { apiFetch } from '@/lib/api/client';
 import { toastError } from '@/lib/api/toast-error';
 import { useConfirmation } from '@/hooks/use-confirmation';
@@ -171,16 +172,13 @@ export function InterestReservationTab({
         />
       )}
 
-      {/* Upload-for-Documenso-signing dialog placeholder. The real
-          dialog (PDF picker + recipient configurator + send button)
-          is part of the larger custom-doc-upload service that's a
-          follow-up. For now show a friendly "coming soon" card. */}
+      {/* Phase 4 — upload-for-Documenso-signing dialog. */}
       {uploadForSigningOpen && (
-        <ComingSoonDialog
+        <UploadForSigningDialog
           open={uploadForSigningOpen}
           onOpenChange={setUploadForSigningOpen}
-          title="Send reservation for signing"
-          body="Upload-and-send-via-Documenso for contracts is being built. For now, draft the reservation externally, get it signed via paper or another tool, then upload the signed copy here."
+          interestId={interestId}
+          documentType="reservation_agreement"
         />
       )}
     </div>
@@ -384,44 +382,3 @@ function StatusBadge({ status }: { status: DocumentRow['status'] }) {
     </Badge>
   );
 }
-
-/**
- * Placeholder for the upload-for-Documenso-signing flow until the
- * full upload + recipient + field-placement service is shipped.
- * Intentional dead-end so reps know the path exists rather than
- * misclicking and getting confusing behaviour.
- */
-function ComingSoonDialog({
-  open,
-  onOpenChange,
-  title,
-  body,
-}: {
-  open: boolean;
-  onOpenChange: (next: boolean) => void;
-  title: string;
-  body: string;
-}) {
-  if (!open) return null;
-  return (
-    <div
-      role="dialog"
-      aria-modal="true"
-      className="fixed inset-0 z-50 flex items-center justify-center bg-black/40 p-4"
-      onClick={() => onOpenChange(false)}
-    >
-      <div
-        className="max-w-md rounded-lg border bg-background p-6 shadow-lg"
-        onClick={(e) => e.stopPropagation()}
-      >
-        <h3 className="text-base font-semibold text-foreground">{title}</h3>
-        <p className="mt-2 text-sm text-muted-foreground">{body}</p>
-        <div className="mt-4 flex justify-end">
-          <Button onClick={() => onOpenChange(false)} size="sm" variant="outline">
-            Got it
-          </Button>
-        </div>
-      </div>
-    </div>
-  );
-}

src/lib/services/document-field-detector.ts

@@ -0,0 +1,297 @@
+/**
+ * Phase 4c — Auto-detect anchor scanner.
+ *
+ * Scans a PDF for common signing-block keywords ("Signature:", "Date:",
+ * "Initials", a long run of underscores, etc.) and proposes Documenso
+ * field placements positioned right after the matched anchor. Output
+ * is in PERCENT coordinates so it lines up with the existing
+ * `DocumensoFieldPlacement` shape consumed by the Phase 3 service.
+ *
+ * Confidence calculation is conservative: an explicit keyword match
+ * scores higher than a generic underscore-run; the field-type-specific
+ * regexes are tried in priority order so a `"Date of Signature:"`
+ * anchor doesn't double-place as both DATE and SIGNATURE.
+ *
+ * This is intentionally pdf-content driven (text-extraction based) —
+ * the alternative (image-of-PDF + OCR) is the bigger berth-PDF parser
+ * tier-3 path; we keep this lightweight so it runs in <500ms on a
+ * 10-page contract.
+ */
+
+import type { DocumensoFieldType } from '@/lib/services/documenso-client';
+
+/** Result of detection, one entry per matched anchor. */
+export interface DetectedField {
+  type: DocumensoFieldType;
+  /** 1-indexed page number. */
+  pageNumber: number;
+  /** All four values are 0-100 percent of page dimensions. */
+  pageX: number;
+  pageY: number;
+  pageWidth: number;
+  pageHeight: number;
+  /** 0..1 — how sure the scanner is. */
+  confidence: number;
+  /** Verbatim anchor that triggered the detection (display + debug). */
+  anchorText: string;
+  /** Inferred recipient label ("Buyer", "Seller", "Client", "Witness",
+   *  "Developer", "Notary", null). Phase 4d maps these to recipients
+   *  by role/name. */
+  inferredRecipientLabel?: string | null;
+}
+
+/** Anchor → field-type pattern table. Order matters: earlier patterns
+ *  win when two anchors overlap on the same text item (e.g. "Date of
+ *  Signature" matches both DATE and SIGNATURE — DATE goes first because
+ *  it's the more specific pattern). */
+interface AnchorPattern {
+  type: DocumensoFieldType;
+  /** Test against lower-cased anchor text. */
+  match: RegExp;
+  /** Suggested field box in PDF points (72 dpi). Converted to percent
+   *  per-page after extraction. */
+  widthPt: number;
+  heightPt: number;
+  /** Bias added to the base confidence. Specific keywords get a bump
+   *  over the generic underscore catch-all. */
+  confidenceBoost: number;
+}
+
+const ANCHOR_PATTERNS: AnchorPattern[] = [
+  // DATE — more specific than SIGNATURE for the common "Date of
+  // Signature:" case, so listed first.
+  {
+    type: 'DATE',
+    match: /(?:dated|date(?:\s+of\s+signature)?)[:\s_-]+/i,
+    widthPt: 80,
+    heightPt: 20,
+    confidenceBoost: 0.2,
+  },
+  // INITIALS — pre-empts NAME because "Initial:" is short and unique.
+  {
+    type: 'INITIALS',
+    match: /(?:^|\b)(?:initials?)[:\s_-]+/i,
+    widthPt: 50,
+    heightPt: 30,
+    confidenceBoost: 0.2,
+  },
+  // EMAIL — explicit email anchor.
+  {
+    type: 'EMAIL',
+    match: /(?:^|\b)e-?mail[:\s_-]+/i,
+    widthPt: 200,
+    heightPt: 20,
+    confidenceBoost: 0.2,
+  },
+  // NAME — printed/full name labels.
+  {
+    type: 'NAME',
+    match: /(?:^|\b)(?:printed\s*)?(?:full\s+)?name[:\s_-]+/i,
+    widthPt: 150,
+    heightPt: 20,
+    confidenceBoost: 0.15,
+  },
+  // SIGNATURE — broadest of the signing-block patterns.
+  {
+    type: 'SIGNATURE',
+    match: /(?:^|\b)(?:signature|sign\s*here|signed\s*by|signed\s*at)[:\s_-]+/i,
+    widthPt: 150,
+    heightPt: 30,
+    confidenceBoost: 0.2,
+  },
+  // SIGNATURE — explicit "X" mark followed by a blank line.
+  {
+    type: 'SIGNATURE',
+    match: /X\s*_{4,}/,
+    widthPt: 150,
+    heightPt: 30,
+    confidenceBoost: 0.15,
+  },
+  // Catch-all: a run of underscores not preceded by a more specific
+  // keyword (which would have matched above). Defaults to TEXT.
+  {
+    type: 'TEXT',
+    match: /_{8,}/,
+    widthPt: 200,
+    heightPt: 20,
+    confidenceBoost: 0,
+  },
+];
+
+/** Recipient labels we know how to match against. Kept in priority
+ *  order so "Buyer Notary" wins NOTARY (more specific than BUYER on a
+ *  notary-block tail). Each entry is lower-cased. */
+const RECIPIENT_LABELS: Array<{ label: string; aliases: string[] }> = [
+  { label: 'Notary', aliases: ['notary', 'witness'] },
+  { label: 'Witness', aliases: ['witness'] },
+  { label: 'Developer', aliases: ['developer', 'seller', 'vendor'] },
+  { label: 'Approver', aliases: ['approver', 'manager'] },
+  { label: 'Buyer', aliases: ['buyer', 'purchaser', 'client'] },
+  { label: 'Seller', aliases: ['seller', 'vendor'] },
+  { label: 'Client', aliases: ['client', 'customer'] },
+];
+
+/** A single text item returned by pdfjs-dist. The transform array
+ *  encodes the position + scale of the text via PDF's affine matrix:
+ *  `[scaleX, skewY, skewX, scaleY, translateX, translateY]`. We use
+ *  `(translateX, translateY)` as the anchor's lower-left corner. */
+interface PdfTextItem {
+  str: string;
+  /** PDF affine [a, b, c, d, e, f]. (e, f) is position. */
+  transform: number[];
+  /** Item width in PDF user-space units. */
+  width?: number;
+  /** Item height — usually equals scaleY. */
+  height?: number;
+}
+
+interface PdfPageView {
+  pageNumber: number;
+  widthPt: number;
+  heightPt: number;
+  items: PdfTextItem[];
+}
+
+/**
+ * Detect signing-block fields in a PDF. Each detection points at the
+ * position immediately after the matched anchor text and is offset 5pt
+ * to the right so the placeholder doesn't visually overlap the
+ * keyword.
+ *
+ * Returns an empty array when the PDF has no extractable text (image-
+ * only scans). The caller should fall back to drag-place-manual in
+ * that case.
+ */
+export async function detectFields(pdfBuffer: Buffer): Promise<DetectedField[]> {
+  const pages = await extractPdfPages(pdfBuffer);
+  const detected: DetectedField[] = [];
+
+  for (const page of pages) {
+    for (const item of page.items) {
+      const lower = item.str.toLowerCase();
+      // Skip if the item has no positional data — defensive against
+      // exotic PDF encodings.
+      if (!Array.isArray(item.transform) || item.transform.length < 6) continue;
+      const translateX = Number(item.transform[4]);
+      const translateY = Number(item.transform[5]);
+      if (!Number.isFinite(translateX) || !Number.isFinite(translateY)) continue;
+
+      for (const pattern of ANCHOR_PATTERNS) {
+        if (!pattern.match.test(lower)) continue;
+
+        // Place the field immediately after the anchor with a 5pt
+        // horizontal offset. The anchor's width is approximate; pdfjs
+        // sometimes gives a too-small width for short tokens so we
+        // floor at 30pt to avoid the field landing on top of the text.
+        const anchorWidthPt = Math.max(30, item.width ?? lower.length * 5);
+        const fieldXPt = translateX + anchorWidthPt + 5;
+        // PDF user-space origin is the lower-left; transform[5] is the
+        // baseline of the text so the field's lower-left also lives
+        // there. CSS/web origin is top-left — we keep the percent in
+        // PDF coordinates here because Documenso accepts both (the
+        // existing placeFields helper handles the conversion).
+        const fieldYPt = translateY;
+
+        const pageX = (fieldXPt / page.widthPt) * 100;
+        const pageY = (fieldYPt / page.heightPt) * 100;
+        const pageWidth = (pattern.widthPt / page.widthPt) * 100;
+        const pageHeight = (pattern.heightPt / page.heightPt) * 100;
+
+        // Hard-skip fields that would land off-page (defensive — a
+        // misparsed transform can blow up the coordinate space).
+        if (pageX < 0 || pageX > 95 || pageY < 0 || pageY > 95) continue;
+        if (pageWidth <= 0 || pageHeight <= 0) continue;
+
+        const recipientLabel = inferRecipient(page.items, item, translateX, translateY);
+
+        detected.push({
+          type: pattern.type,
+          pageNumber: page.pageNumber,
+          pageX,
+          pageY,
+          pageWidth,
+          pageHeight,
+          confidence: 0.5 + pattern.confidenceBoost,
+          anchorText: item.str.trim(),
+          inferredRecipientLabel: recipientLabel,
+        });
+        // First matching pattern wins for this item — earlier
+        // (more-specific) patterns shadow later ones.
+        break;
+      }
+    }
+  }
+  return detected;
+}
+
+/**
+ * Walk the page's other text items within ±100pt of the anchor and
+ * find a recipient-label keyword. Used to seed the recipient
+ * assignment side-panel; the rep can override.
+ */
+function inferRecipient(
+  items: PdfTextItem[],
+  anchor: PdfTextItem,
+  anchorX: number,
+  anchorY: number,
+): string | null {
+  const RADIUS = 100;
+  for (const candidate of items) {
+    if (candidate === anchor) continue;
+    if (!Array.isArray(candidate.transform) || candidate.transform.length < 6) continue;
+    const cx = Number(candidate.transform[4]);
+    const cy = Number(candidate.transform[5]);
+    if (!Number.isFinite(cx) || !Number.isFinite(cy)) continue;
+    if (Math.abs(cx - anchorX) > RADIUS) continue;
+    if (Math.abs(cy - anchorY) > RADIUS) continue;
+    const lower = candidate.str.toLowerCase();
+    for (const { label, aliases } of RECIPIENT_LABELS) {
+      if (aliases.some((alias) => lower.includes(alias))) return label;
+    }
+  }
+  return null;
+}
+
+/**
+ * Extract per-page text + page dimensions from a PDF buffer. Uses
+ * pdfjs-dist (the same library powering react-pdf in the dialog). We
+ * import it dynamically so the heavy native-bindings dep only loads
+ * when the detector actually runs.
+ *
+ * Returns an empty array if pdfjs fails to parse — the rep gets the
+ * manual placement flow without an error toast.
+ */
+export async function extractPdfPages(pdfBuffer: Buffer): Promise<PdfPageView[]> {
+  try {
+    // pdfjs-dist 5.x ships a legacy ESM build that works in Node + Next
+    // server bundles without the worker wiring needed in the browser.
+    const pdfjsLib = await import('pdfjs-dist/legacy/build/pdf.mjs');
+    const data = new Uint8Array(pdfBuffer);
+    const loadingTask = pdfjsLib.getDocument({ data });
+    const pdf = await loadingTask.promise;
+    const pages: PdfPageView[] = [];
+    for (let i = 1; i <= pdf.numPages; i++) {
+      const page = await pdf.getPage(i);
+      const viewport = page.getViewport({ scale: 1 });
+      const content = await page.getTextContent();
+      const items = (content.items as Array<unknown>).filter(isPdfTextItem);
+      pages.push({
+        pageNumber: i,
+        widthPt: viewport.width,
+        heightPt: viewport.height,
+        items,
+      });
+    }
+    return pages;
+  } catch {
+    // Image-only scans or corrupt PDFs land here. The dialog falls
+    // back to manual placement — no rep-facing error needed.
+    return [];
+  }
+}
+
+function isPdfTextItem(item: unknown): item is PdfTextItem {
+  if (!item || typeof item !== 'object') return false;
+  const i = item as Record<string, unknown>;
+  return typeof i.str === 'string' && Array.isArray(i.transform);
+}

tests/unit/services/document-field-detector.test.ts

@@ -0,0 +1,107 @@
+import { describe, it, expect, vi } from 'vitest';
+
+// Mock pdfjs-dist before importing the service. The detector calls
+// `import('pdfjs-dist/legacy/build/pdf.mjs')` dynamically; we stub the
+// module with a fake document whose pages return canned text items so
+// we can assert the anchor-matching + coordinate-conversion logic
+// without needing a real PDF.
+vi.mock('pdfjs-dist/legacy/build/pdf.mjs', () => ({
+  getDocument: (_opts: unknown) => ({
+    promise: Promise.resolve({
+      numPages: 1,
+      getPage: async (_n: number) => ({
+        getViewport: ({ scale: _s }: { scale: number }) => ({
+          width: 595, // A4 in pt
+          height: 842,
+        }),
+        getTextContent: async () => ({
+          items: [
+            // Item 0: a signature anchor near the bottom-left
+            {
+              str: 'Signature: ',
+              transform: [1, 0, 0, 1, 50, 100],
+              width: 70,
+            },
+            // Item 1: a date anchor next to it
+            {
+              str: 'Date: ',
+              transform: [1, 0, 0, 1, 250, 100],
+              width: 40,
+            },
+            // Item 2: recipient label nearby
+            {
+              str: 'Buyer',
+              transform: [1, 0, 0, 1, 50, 130],
+              width: 40,
+            },
+            // Item 3: unrelated body text (should not match)
+            {
+              str: 'The parties hereby agree…',
+              transform: [1, 0, 0, 1, 50, 200],
+              width: 200,
+            },
+          ],
+        }),
+      }),
+    }),
+  }),
+}));
+
+import { detectFields } from '@/lib/services/document-field-detector';
+
+describe('detectFields', () => {
+  it('returns matches for known anchors with the right type + page', async () => {
+    const result = await detectFields(Buffer.from('%PDF-1.7'));
+    expect(result.length).toBeGreaterThanOrEqual(2);
+    const sig = result.find((r) => r.type === 'SIGNATURE');
+    const date = result.find((r) => r.type === 'DATE');
+    expect(sig).toBeDefined();
+    expect(date).toBeDefined();
+    expect(sig?.pageNumber).toBe(1);
+    expect(date?.pageNumber).toBe(1);
+  });
+
+  it('infers recipient label from nearby text', async () => {
+    const result = await detectFields(Buffer.from('%PDF-1.7'));
+    const sig = result.find((r) => r.type === 'SIGNATURE');
+    expect(sig?.inferredRecipientLabel).toBe('Buyer');
+  });
+
+  it('returns percent coordinates in [0, 100]', async () => {
+    const result = await detectFields(Buffer.from('%PDF-1.7'));
+    for (const f of result) {
+      expect(f.pageX).toBeGreaterThanOrEqual(0);
+      expect(f.pageX).toBeLessThanOrEqual(100);
+      expect(f.pageY).toBeGreaterThanOrEqual(0);
+      expect(f.pageY).toBeLessThanOrEqual(100);
+      expect(f.pageWidth).toBeGreaterThan(0);
+      expect(f.pageHeight).toBeGreaterThan(0);
+    }
+  });
+
+  it('attaches the anchor text + a confidence score', async () => {
+    const result = await detectFields(Buffer.from('%PDF-1.7'));
+    const sig = result.find((r) => r.type === 'SIGNATURE');
+    expect(sig?.anchorText).toMatch(/signature/i);
+    expect(sig?.confidence).toBeGreaterThan(0.5);
+    expect(sig?.confidence).toBeLessThanOrEqual(1);
+  });
+
+  it('does not match body text that lacks a signing-block keyword', async () => {
+    const result = await detectFields(Buffer.from('%PDF-1.7'));
+    // The "The parties hereby agree" item should not produce a TEXT
+    // detection (no underscore run, no keyword).
+    expect(result.find((r) => r.anchorText?.includes('parties'))).toBeUndefined();
+  });
+
+  it('gracefully returns [] when pdfjs throws', async () => {
+    // Force pdfjs to reject for this one call
+    const mod = await import('pdfjs-dist/legacy/build/pdf.mjs');
+    const orig = mod.getDocument;
+    (mod as unknown as { getDocument: typeof orig }).getDocument = () =>
+      ({ promise: Promise.reject(new Error('boom')) }) as ReturnType<typeof orig>;
+    const result = await detectFields(Buffer.from('not-a-pdf'));
+    expect(result).toEqual([]);
+    (mod as unknown as { getDocument: typeof orig }).getDocument = orig;
+  });
+});