diff --git a/apps/api/prisma/migrations/20260811120000_doe_notice_url_backfill/migration.sql b/apps/api/prisma/migrations/20260811120000_doe_notice_url_backfill/migration.sql
new file mode 100644
index 0000000..7df484b
--- /dev/null
+++ b/apps/api/prisma/migrations/20260811120000_doe_notice_url_backfill/migration.sql
@@ -0,0 +1,43 @@
+-- Backfill for the DÖE notice links.
+--
+-- Until 2026-08-11 the doe-opendata adapter stored the OCDS document's own
+-- `uri` as Tender.sourceUrl. That is the API address of the record: it serves
+-- OCDS JSON by design, so every user who followed the link from the results
+-- list, the detail view, or an alert mail landed on raw JSON instead of the
+-- notice. The adapter now builds the human-readable notice page instead, but
+-- rows already ingested keep the broken URL until this migration rewrites
+-- them.
+--
+-- The id inside the API URL is the same value the row already carries in
+-- sourceNoticeId (verified against the live feed on 2026-08-11: for a single
+-- notice, `uri`'s id and `releases[0].id` are identical). The page address is
+-- therefore derivable from stored data alone -- no refetch, no user input
+-- interpolated.
+--
+-- Two shapes of notice id occur in the feed and both were verified to render
+-- the correct notice in a browser: numeric ("25673764") and UUID
+-- ("7085ba12-c7f4-4f8c-8599-2fe9e4e2737c"). The WHERE clause restricts the
+-- rewrite to ids made of those characters, so a row with an unexpected id
+-- shape keeps its old value rather than getting a URL built from something
+-- that was never checked.
+--
+-- Idempotent: only rows still pointing at /api/notices/ are touched. Running
+-- it twice changes nothing the second time.
+
+UPDATE "Tender"
+SET "sourceUrl" =
+  'https://oeffentlichevergabe.de/ui/de/search/details?noticeId=' || "sourceNoticeId"
+WHERE "sourcePortal" = 'doe-opendata'
+  AND "sourceUrl" LIKE 'https://oeffentlichevergabe.de/api/notices/%'
+  AND "sourceNoticeId" ~ '^[A-Za-z0-9-]+$';
+
+-- Same rewrite for the per-source rows behind a deduplicated tender. The
+-- detail view lists these separately (tenders.controller.ts), so leaving them
+-- untouched would keep broken links visible even after the primary column is
+-- fixed.
+UPDATE "TenderSource"
+SET "sourceUrl" =
+  'https://oeffentlichevergabe.de/ui/de/search/details?noticeId=' || "sourceNoticeId"
+WHERE "sourcePortal" = 'doe-opendata'
+  AND "sourceUrl" LIKE 'https://oeffentlichevergabe.de/api/notices/%'
+  AND "sourceNoticeId" ~ '^[A-Za-z0-9-]+$';
diff --git a/apps/api/src/tenders/adapters/doe-opendata.adapter.spec.ts b/apps/api/src/tenders/adapters/doe-opendata.adapter.spec.ts
index e008e08..1b2d702 100644
--- a/apps/api/src/tenders/adapters/doe-opendata.adapter.spec.ts
+++ b/apps/api/src/tenders/adapters/doe-opendata.adapter.spec.ts
@@ -2,7 +2,7 @@ import AdmZip from 'adm-zip';
 import { readFileSync } from 'fs';
 import { join } from 'path';
 import { afterEach, describe, expect, it, vi } from 'vitest';
-import { DoeOpenDataAdapter } from './doe-opendata.adapter';
+import { buildDoeNoticeUrl, DoeOpenDataAdapter } from './doe-opendata.adapter';
 
 /**
  * Real, trimmed DÖE day-export fixtures (8 notices, captured live from
@@ -129,6 +129,42 @@ describe('DoeOpenDataAdapter', () => {
     await expect(adapter.fetchTenders(TEST_PUBDAY)).rejects.toThrow();
   });
 
+  // Backlog item 2026-08-05: sourceUrl used to be the OCDS document's own
+  // `uri`, which is the API address and answers with JSON. Users following a
+  // link from the results list, the detail view or an alert mail landed on raw
+  // JSON instead of the notice.
+  it('points sourceUrl at the human-readable notice page, never at the API', async () => {
+    stubFetchWithFixtures();
+    const adapter = new DoeOpenDataAdapter();
+
+    const records = await adapter.fetchTenders(TEST_PUBDAY);
+
+    expect(records.length).toBe(EXPECTED_TENDER_TAGGED_COUNT);
+    for (const record of records) {
+      expect(record.sourceUrl).toBe(
+        `https://oeffentlichevergabe.de/ui/de/search/details?noticeId=${record.sourceNoticeId}`,
+      );
+      // The exact shape that was broken — an API address serving OCDS JSON.
+      expect(record.sourceUrl).not.toContain('/api/notices/');
+      expect(record.sourceUrl).not.toContain('format=ocds');
+    }
+  });
+
+  it('builds the notice URL from both id shapes the feed uses, escaping the id', () => {
+    // Numeric and UUID ids both occur in the live feed; both were verified in
+    // a browser on 2026-08-11 to render the correct notice.
+    expect(buildDoeNoticeUrl('25673764')).toBe(
+      'https://oeffentlichevergabe.de/ui/de/search/details?noticeId=25673764',
+    );
+    expect(buildDoeNoticeUrl('7085ba12-c7f4-4f8c-8599-2fe9e4e2737c')).toBe(
+      'https://oeffentlichevergabe.de/ui/de/search/details?noticeId=7085ba12-c7f4-4f8c-8599-2fe9e4e2737c',
+    );
+    // An id is directory data, not something to paste into a URL unchecked.
+    expect(buildDoeNoticeUrl('a b&c=d')).toBe(
+      'https://oeffentlichevergabe.de/ui/de/search/details?noticeId=a%20b%26c%3Dd',
+    );
+  });
+
   it('never imports or uses axios (native fetch is the sole HTTP client convention)', () => {
     const source = readFileSync(
       join(__dirname, 'doe-opendata.adapter.ts'),
diff --git a/apps/api/src/tenders/adapters/doe-opendata.adapter.ts b/apps/api/src/tenders/adapters/doe-opendata.adapter.ts
index 667bd6d..e5da0be 100644
--- a/apps/api/src/tenders/adapters/doe-opendata.adapter.ts
+++ b/apps/api/src/tenders/adapters/doe-opendata.adapter.ts
@@ -43,6 +43,27 @@ interface OcdsDocument {
   releases?: OcdsRelease[];
 }
 
+/**
+ * Human-readable notice page for a DÖE notice id.
+ *
+ * The OCDS document's own `uri` field is the API address of the record — it
+ * serves OCDS JSON by design, so a user who follows it lands on raw JSON
+ * instead of the notice. The id in that URL is the same `releases[0].id` the
+ * adapter already stores as sourceNoticeId, so the page can be addressed
+ * without a second lookup.
+ *
+ * `/ui/de/search/details?noticeId=…` is the redirect target of
+ * `/ui/de/notices/…` and therefore the form that needs no redirect. Verified
+ * in a browser on 2026-08-11 for both id shapes that occur in the feed: the
+ * numeric one (25673764 -> "Feuerwehr-Gerätehaus Miehlen Fliesenarbeiten")
+ * and the UUID one (7085ba12-… -> "Holzfassade"). Note that the page is a
+ * single-page app: it answers HTTP 200 with an identical shell for ANY id,
+ * so a status-code check proves nothing here — only rendered content does.
+ */
+export function buildDoeNoticeUrl(noticeId: string): string {
+  return `https://oeffentlichevergabe.de/ui/de/search/details?noticeId=${encodeURIComponent(noticeId)}`;
+}
+
 /**
  * D-02 open-tender filter (RESEARCH.md Pattern 2 / Pitfall C): positive
  * tag-presence match only. Missing/other tags (award, planning, or no tag
@@ -124,7 +145,8 @@ export class DoeOpenDataAdapter implements TenderSourceAdapter {
         sourcePortal: 'doe-opendata',
         sourceNoticeId: release.id,
         ocid: release.ocid,
-        sourceUrl: ocdsDocument.uri,
+        // NOT ocdsDocument.uri — that is the API address and serves JSON.
+        sourceUrl: buildDoeNoticeUrl(release.id),
         fetchedAt,
         publishedAt: ocdsDocument.publishedDate
           ? new Date(ocdsDocument.publishedDate)
diff --git a/apps/api/src/tenders/doe-url-migration-sql.spec.ts b/apps/api/src/tenders/doe-url-migration-sql.spec.ts
new file mode 100644
index 0000000..32dbcfc
--- /dev/null
+++ b/apps/api/src/tenders/doe-url-migration-sql.spec.ts
@@ -0,0 +1,68 @@
+import { readdirSync, readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { describe, expect, it } from 'vitest';
+
+/**
+ * Prüft das hand-geschriebene Backfill-SQL für die DÖE-Bekanntmachungslinks
+ * ohne Datenbank — reiner Textabgleich, gleiches Muster wie
+ * groups/migration-sql.spec.ts.
+ *
+ * Der Adapter allein repariert nur neue Importe. Ohne den Nachlauf behalten
+ * die bereits importierten Ausschreibungen ihre kaputte API-URL, und genau
+ * die sieht der Nutzer heute in Trefferliste, Detailansicht und Alarm-Mail.
+ */
+
+const MIGRATIONS_DIR = join(__dirname, '../../prisma/migrations');
+
+function readMigrationSql(suffix: string): string {
+  const dirs = readdirSync(MIGRATIONS_DIR, { withFileTypes: true })
+    .filter((entry) => entry.isDirectory() && entry.name.endsWith(suffix))
+    .map((entry) => entry.name);
+
+  if (dirs.length !== 1) {
+    throw new Error(
+      `Expected exactly one migration directory ending in "${suffix}", found ${dirs.length}: ${dirs.join(', ')}`,
+    );
+  }
+
+  return readFileSync(join(MIGRATIONS_DIR, dirs[0], 'migration.sql'), 'utf-8');
+}
+
+describe('doe_notice_url_backfill migration.sql', () => {
+  const sql = readMigrationSql('_doe_notice_url_backfill');
+
+  it('schreibt die Bekanntmachungsseite, nicht die API-Adresse', () => {
+    expect(sql).toContain(
+      "'https://oeffentlichevergabe.de/ui/de/search/details?noticeId=' || \"sourceNoticeId\"",
+    );
+    expect(sql).not.toMatch(/SET\s+"sourceUrl"\s*=\s*'[^']*\/api\/notices\//);
+  });
+
+  it('fasst beide Tabellen an — sonst bleiben die Quell-Links der zusammengefuehrten Tender kaputt', () => {
+    expect(sql).toMatch(/UPDATE\s+"Tender"/);
+    expect(sql).toMatch(/UPDATE\s+"TenderSource"/);
+  });
+
+  it('ist idempotent: nur Zeilen, die noch auf die API zeigen', () => {
+    const updates = sql.match(/UPDATE\s+"[A-Za-z]+"[\s\S]*?;/g) ?? [];
+    expect(updates.length).toBe(2);
+    for (const stmt of updates) {
+      expect(stmt).toContain(
+        `"sourceUrl" LIKE 'https://oeffentlichevergabe.de/api/notices/%'`,
+      );
+      expect(stmt).toContain(`"sourcePortal" = 'doe-opendata'`);
+    }
+  });
+
+  it('baut keine URL aus einer Kennung unerwarteter Form', () => {
+    const updates = sql.match(/UPDATE\s+"[A-Za-z]+"[\s\S]*?;/g) ?? [];
+    for (const stmt of updates) {
+      expect(stmt).toContain(`"sourceNoticeId" ~ '^[A-Za-z0-9-]+$'`);
+    }
+  });
+
+  it('fasst ausschliesslich DÖE-Zeilen an — andere Portale behalten ihre Links', () => {
+    expect(sql).not.toMatch(/UPDATE[\s\S]*?service-bund/);
+    expect(sql).not.toMatch(/UPDATE[\s\S]*?cosinex/);
+  });
+});