M1: backend core + proposal engine

- FastAPI skeleton, SQLAlchemy models (§13), Alembic initial migration
- SchedulingProvider interface with google_calendar (free/busy read-only),
  partner_api (Appendix B client) and mock implementations
- Proposal engine: create → provider-routed delivery → owner actions
  (resolve/confirm+SMS/reject) → expiry + reminders (§9)
- Signed single-use action links, .ics METHOD:REQUEST attachment
- Partner outcome webhook with HMAC verification + polling fallback
- SmsProvider (console) with Bosnian templates (§5.5), EmailProvider (console/SMTP)
- Fake partner API server in tests/ — Appendix B reference implementation
- 43 tests: slot math, proposal lifecycle, action links, partner contract

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_action_links.py

@@ -0,0 +1,133 @@
+"""Owner email action links over HTTP (§9.1-9.2, idempotency per §15)."""
+
+import re
+from datetime import UTC, datetime, timedelta
+
+from gogo.domain import BookingStatus
+from tests.test_proposal_lifecycle import create
+
+
+def extract_links(text: str) -> dict[str, str]:
+    """Pull action URLs out of the plain-text proposal email."""
+    links = {}
+    resolve = re.search(r"RIJEŠENO[^\n]*\n\s+(http\S+)", text)
+    confirm = re.search(r"POTVRDI[^\n]*\n\s+(http\S+)", text)
+    reject = re.search(r"ODBIJ[^\n]*\n\s+(http\S+)", text)
+    if resolve:
+        links["resolve"] = resolve.group(1)
+    if confirm:
+        links["confirm"] = confirm.group(1)
+    if reject:
+        links["reject"] = reject.group(1)
+    return links
+
+
+async def test_resolve_link_closes_request_no_sms(session, tenant, emails, sms, gogo_client):
+    req, _ = await create(session, tenant)
+    await session.commit()
+    links = extract_links(emails[0].text)
+
+    resp = await gogo_client.get(links["resolve"])
+    assert resp.status_code == 200
+    assert "Označeno kao riješeno" in resp.text
+
+    await session.refresh(req)
+    assert req.status == BookingStatus.resolved_by_owner.value
+    assert sms == []
+
+    # idempotent: second click shows friendly "already handled" page
+    resp2 = await gogo_client.get(links["resolve"])
+    assert resp2.status_code == 200
+    assert "već obrađen" in resp2.text
+
+
+async def test_confirm_link_sends_sms(session, tenant, emails, sms, gogo_client):
+    req, _ = await create(session, tenant)
+    await session.commit()
+    links = extract_links(emails[0].text)
+
+    resp = await gogo_client.get(links["confirm"])
+    assert resp.status_code == 200
+    assert "Termin potvrđen" in resp.text
+
+    await session.refresh(req)
+    assert req.status == BookingStatus.confirmed.value
+    assert len(sms) == 1
+    assert "Potvrđen termin" in sms[0][1]
+
+
+async def test_reject_link_shows_editable_form_then_sends(
+    session, tenant, emails, sms, gogo_client
+):
+    req, _ = await create(session, tenant)
+    await session.commit()
+    links = extract_links(emails[0].text)
+
+    # GET shows the form with the default template prefilled — nothing sent yet
+    resp = await gogo_client.get(links["reject"])
+    assert resp.status_code == 200
+    assert "<textarea" in resp.text
+    assert sms == []
+
+    resp = await gogo_client.post(
+        links["reject"] + "/reject", data={"sms_body": "Nažalost, popunjeni smo. Salon Merima"}
+    )
+    assert resp.status_code == 200
+    await session.refresh(req)
+    assert req.status == BookingStatus.rejected.value
+    assert sms == [("+38765123456", "Nažalost, popunjeni smo. Salon Merima")]
+
+
+async def test_forged_token_rejected(gogo_client, session, tenant):
+    resp = await gogo_client.get("/a/forged-token-value")
+    assert resp.status_code == 400
+    assert "Nevažeći link" in resp.text
+
+
+async def test_action_after_expiry_shows_status(session, tenant, emails, sms, gogo_client):
+    from gogo.proposals import engine as pe
+
+    req, _ = await create(session, tenant)
+    req.expires_at = datetime.now(UTC) - timedelta(minutes=1)
+    await pe.process_expirations(session)
+    await session.commit()
+    sms.clear()
+
+    links = extract_links(emails[0].text)
+    resp = await gogo_client.get(links["confirm"])
+    assert resp.status_code == 200
+    assert "već obrađen" in resp.text
+    assert "istekao" in resp.text
+    assert sms == []
+
+
+async def test_confirm_link_warns_when_slot_taken(session, tenant, emails, sms, gogo_client):
+    """Recheck finds slot busy → warning page with force-confirm, no SMS yet."""
+    from gogo.scheduling.mock import MockProvider
+
+    req, _ = await create(session, tenant)
+    await session.commit()
+    links = extract_links(emails[0].text)
+
+    async def is_slot_free(self, service_id, slot_):
+        return False
+
+    MockProvider.is_slot_free = is_slot_free
+    try:
+        resp = await gogo_client.get(links["confirm"])
+        assert resp.status_code == 200
+        assert "u međuvremenu zauzet" in resp.text
+        await session.refresh(req)
+        assert req.status == BookingStatus.pending.value
+        assert sms == []
+
+        # owner forces the confirmation anyway
+        resp = await gogo_client.post(links["confirm"] + "/force-confirm")
+        assert resp.status_code == 200
+        assert "Termin potvrđen" in resp.text
+    finally:
+        del MockProvider.is_slot_free
+
+    await session.refresh(req)
+    assert req.status == BookingStatus.confirmed.value
+    assert len(sms) == 1