fix: stamp the real signing date next to the signature

backend/app/routers/applications.py

@@ -15,7 +15,7 @@
 from app.services import application_repository as repo
 from app.services import email_service
 from app.services.application_service import ApplicationService
-from app.services.contract_service import ContractService
+from app.services.contract_service import SIGNATURE_DATE_POS, ContractService
 from app.services.pdf_service import pdf_service
 from app.services.storage_service import storage_service
 from app.services.token_service import create_download_token
@@ -144,6 +144,10 @@ def sign_application(index: int, request: SignApplicationRequest):
 
     signed_path = source_pdf.parent / "signed.pdf"
 
+    # Stamp the date the coordinator actually signs, not the date the contract
+    # was generated (which can be days earlier).
+    signed_on = datetime.now(timezone.utc).date().isoformat()
+
     pdf_service.embed_signature(
         source_pdf=source_pdf,
         output_pdf=signed_path,
@@ -153,6 +157,7 @@ def sign_application(index: int, request: SignApplicationRequest):
         y=request.y,
         w=request.w,
         h=request.h,
+        text_stamps=[(signed_on, *SIGNATURE_DATE_POS)],
     )
 
     token = create_download_token(application.contract_task_id)

backend/app/services/contract_service.py

@@ -23,6 +23,11 @@
 _BEAR_BROWN = HexColor("#7A5A2E")
 _PAGE_W, _PAGE_H = A4
 
+# Where the signing date is stamped, in PDF points with a TOP-LEFT origin (the
+# convention pdf_service uses). Mirrors the reportlab position of the date line
+# below, which is drawn at 61 mm from the bottom.
+SIGNATURE_DATE_POS = (_PAGE_W - 73 * mm, _PAGE_H - 63 * mm)
+
 
 class ContractService:
     @staticmethod
@@ -109,9 +114,12 @@ def field(label: str, value: str):
         c.line(left, 61 * mm, left + 70 * mm, 61 * mm)          # signature line
         c.drawString(left, 55 * mm, "Signature of the Dean's Internship Supervisor")
 
+        # The date beside the signature is intentionally left blank here: it is
+        # the date the coordinator signs, which happens later (often days after
+        # the contract is generated). It is stamped during signing, at
+        # SIGNATURE_DATE_POS below.
         c.drawString(_PAGE_W - 85 * mm, 61 * mm, "Date:")
         c.line(_PAGE_W - 73 * mm, 61 * mm, _PAGE_W - 20 * mm, 61 * mm)
-        c.drawString(_PAGE_W - 73 * mm, 63 * mm, date.today().isoformat())
 
         c.setFont("Helvetica-Oblique", 7)
         c.drawString(left, 15 * mm,

backend/app/services/pdf_service.py

@@ -196,6 +196,7 @@ def embed_signature(
         y: float,
         w: float,
         h: float,
+        text_stamps: list[tuple[str, float, float]] | None = None,
     ) -> None:
         """Embed *image_bytes* on *page_index* of *source_pdf*, save to *output_pdf*.
 
@@ -204,6 +205,10 @@ def embed_signature(
                     using page top-left as origin with y growing downward.
             w, h — box width and height in PDF points (both must be > 0).
 
+        text_stamps — optional (text, x, y) items drawn on the same page in the
+            same save, for values that are only known at signing time (the
+            signing date). Same top-left origin as above.
+
         Save options (garbage=3, deflate=True, clean=True):
             - Drop orphan objects and duplicate streams (garbage=3).
             - zlib-compress all streams (deflate=True).
@@ -250,6 +255,13 @@ def embed_signature(
                     f"PyMuPDF rejected the signature image: {exc}"
                 ) from exc
 
+            for text, tx, ty in (text_stamps or []):
+                try:
+                    page.insert_text((tx, ty), text, fontsize=10, fontname="helv")
+                except (ValueError, RuntimeError) as exc:
+                    # A stamp is supplementary — never lose the signature over it.
+                    logger.warning("could not stamp %r: %s", text, exc)
+
             try:
                 doc.save(
                     str(part_path),

backend/tests/test_api.py

@@ -188,3 +188,42 @@ def test_sign_pdf_download_url_is_reachable():
     download = client.get(download_url)
     assert download.status_code == 200
     assert download.headers["content-type"] == "application/pdf"
+
+
+def test_signature_date_is_stamped_at_signing_not_generation(tmp_path):
+    """The date beside the signature must be the date the coordinator signed.
+
+    It used to be printed by create_contract_pdf, i.e. when the contract was
+    generated — often days before signing — so a contract signed on the 21st
+    still showed the 16th. Generation must leave it blank; signing stamps it.
+    """
+    from datetime import datetime, timezone
+
+    from app.services.contract_service import SIGNATURE_DATE_POS, ContractService
+    from app.services.pdf_service import pdf_service
+
+    unsigned = tmp_path / "contract.pdf"
+    ContractService.create_contract_pdf(
+        name="Ada Lovelace", email="ada@example.com",
+        recommended_role="Backend Developer Internship",
+        candidate_score=80, output_path=unsigned,
+    )
+
+    today = datetime.now(timezone.utc).date().isoformat()
+    unsigned_text = fitz.open(str(unsigned))[0].get_text()
+    # Only the header "Date:" field carries a date before signing.
+    assert unsigned_text.count(today) == 1
+
+    img = Image.new("RGBA", (60, 25), (0, 0, 255, 255))
+    buf = io.BytesIO()
+    img.save(buf, format="PNG")
+
+    signed = tmp_path / "signed.pdf"
+    pdf_service.embed_signature(
+        source_pdf=unsigned, output_pdf=signed, image_bytes=buf.getvalue(),
+        page_index=0, x=70, y=600, w=220, h=70,
+        text_stamps=[(today, *SIGNATURE_DATE_POS)],
+    )
+
+    signed_text = fitz.open(str(signed))[0].get_text()
+    assert signed_text.count(today) == 2      # header + signing date