diff --git a/docs/api/openapi.yaml b/docs/api/openapi.yaml
index 5be68b466..22c56b089 100644
--- a/docs/api/openapi.yaml
+++ b/docs/api/openapi.yaml
@@ -21065,7 +21065,7 @@ paths:
                   maxLength: 2048
                 organizationId:
                   type: string
-                  pattern: ^[A-Za-z0-9_-]{1,128}$
+                  pattern: ^org_[a-z0-9]{24}$
                 token:
                   type: string
                   minLength: 1
@@ -21085,7 +21085,9 @@ paths:
         "404": &a55
           description: "`documents.sources.unavailable`: the operator has not listed any origin in `DOCUMENT_SOURCE_ORIGINS`, so
             the picker is off. `documents.sources.notConnected`: no connection is saved for this system.
-            `documents.sources.notFound`: the source has no such document, or (Papra) no such organization."
+            `documents.sources.notFound`: the source has no such document, or (Papra) no such organization, including
+            one the key's user is not a member of (Papra 403 `user.not_in_organization`) and one Papra cannot parse
+            (400)."
           content:
             application/json:
               schema:
@@ -21104,7 +21106,8 @@ paths:
             all, its HTTP status in `meta.upstreamStatus` (its body is never passed on): `documents.sources.unreachable`
             (no connection, timeout, or a destination refused at dial time), `documents.sources.redirected` (the source
             answered with a redirect, which is never followed), `documents.sources.authRefused` (401/403 from the
-            source), `documents.sources.versionTooOld` (Paperless-ngx older than 2.16 / API version 9),
+            source), `documents.sources.permissionMissing` (Papra: the key cannot read tags; needs `tags:read`),
+            `documents.sources.versionTooOld` (Paperless-ngx older than 2.16 / API version 9),
             `documents.sources.badResponse` (not the documented JSON, or larger than 1 MiB)."
           content:
             application/json:
@@ -21327,9 +21330,10 @@ paths:
         "404":
           description: "`documents.sources.unavailable`: the operator has not listed any origin in `DOCUMENT_SOURCE_ORIGINS`, so
             the picker is off. `documents.sources.notConnected`: no connection is saved for this system.
-            `documents.sources.notFound`: the source has no such document, or (Papra) no such organization.
-            `documents.sources.linkTargetNotFound`: the record in `link` is not the caller's own live conditionEpisode /
-            encounter / vaccination."
+            `documents.sources.notFound`: the source has no such document, or (Papra) no such organization, including
+            one the key's user is not a member of (Papra 403 `user.not_in_organization`) and one Papra cannot parse
+            (400). `documents.sources.linkTargetNotFound`: the record in `link` is not the caller's own live
+            conditionEpisode / encounter / vaccination."
           content:
             application/json:
               schema:
@@ -31239,13 +31243,13 @@ components:
                 documents.sources.authRefused, documents.sources.badResponse, documents.sources.browserOnly,
                 documents.sources.invalidAddress, documents.sources.linkTargetNotFound, documents.sources.notConnected,
                 documents.sources.notFound, documents.sources.organizationRequired, documents.sources.originNotAllowed,
-                documents.sources.rateLimited, documents.sources.redirected, documents.sources.tokenRequired,
-                documents.sources.unavailable, documents.sources.unreachable, documents.sources.versionTooOld; encounter
-                — encounter.invalid, encounter.link.invalid, encounter.practitioner-not-found,
-                encounter.reminder-conflict, encounter.reminder-not-found; environment — environment.invalid,
-                environment.no_home, environment.range_too_large, environment.travel.not_found; export —
-                export.selection.empty, export.selection.unknown_leaf; familyHistory — familyHistory.invalid; feedback —
-                feedback.body.invalid; health_score_config — health_score_config.invalid,
+                documents.sources.permissionMissing, documents.sources.rateLimited, documents.sources.redirected,
+                documents.sources.tokenRequired, documents.sources.unavailable, documents.sources.unreachable,
+                documents.sources.versionTooOld; encounter — encounter.invalid, encounter.link.invalid,
+                encounter.practitioner-not-found, encounter.reminder-conflict, encounter.reminder-not-found; environment
+                — environment.invalid, environment.no_home, environment.range_too_large, environment.travel.not_found;
+                export — export.selection.empty, export.selection.unknown_leaf; familyHistory — familyHistory.invalid;
+                feedback — feedback.body.invalid; health_score_config — health_score_config.invalid,
                 health_score_config.too_narrow; illness — illness.day-log.invalid, illness.disabled,
                 illness.episode.chronic-no-resolve, illness.episode.invalid, illness.episode.invalid-window,
                 illness.episode.parent-not-found, illness.insights.invalid; import — import.write_failed; ingest —
diff --git a/messages/de.json b/messages/de.json
index b0426eec2..3dead10f6 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -6711,7 +6711,7 @@
       "baseUrl": "Adresse",
       "allowedOrigins": "Auf diesem Server erlaubt: {origins}",
       "organizationId": "Organisations-ID",
-      "organizationHelp": "Der Teil nach /organizations/ in der Adresszeile von Papra.",
+      "organizationHelp": "Der Teil nach /organizations/ in der Adresszeile von Papra. Papra-Organisations-IDs sehen aus wie org_ gefolgt von 24 Buchstaben und Ziffern.",
       "token": "API-Token",
       "tokenSaved": "Für diese Adresse gespeichert. Leer lassen, um es zu behalten.",
       "tokenHelpPaperless": "In Paperless-ngx: Mein Profil, API-Token.",
@@ -10220,7 +10220,7 @@
         "authRefused": "Das Archiv hat das Token abgelehnt. Prüfe das Token und seine Berechtigungen.",
         "versionTooOld": "Das Archiv ist zu alt. Nötig ist Paperless-ngx 2.16 oder neuer.",
         "badResponse": "Die Antwort des Archivs ließ sich nicht lesen. Prüfe, ob die Adresse auf das Archiv selbst zeigt.",
-        "notFound": "Das Archiv kennt dieses Dokument oder diese Organisation nicht.",
+        "notFound": "Das Archiv kennt dieses Dokument nicht, oder die Organisations-ID ist falsch oder nicht deine.",
         "linkTargetNotFound": "Der Eintrag, mit dem verknüpft werden sollte, existiert nicht mehr.",
         "rateLimited": "Zu viele Anfragen. Warte eine Minute und versuche es erneut.",
         "browserOnly": "Dokumentarchive lassen sich nur im Browser verwenden.",
@@ -10233,7 +10233,8 @@
         "uploadLimit": "Das stündliche Upload-Limit ist erreicht. Versuche es später erneut.",
         "uploadBusy": "Andere Uploads laufen noch. Versuche es gleich noch einmal.",
         "moduleDisabled": "Dokumente sind in den Einstellungen ausgeschaltet.",
-        "generic": "Etwas ist schiefgelaufen. Versuche es erneut."
+        "generic": "Etwas ist schiefgelaufen. Versuche es erneut.",
+        "permissionMissing": "Der Papra-Schlüssel darf keine Tags lesen. Gib ihm die Berechtigung tags:read."
       },
       "pickMore": "Weitere auswählen",
       "finishedHint": "Suche erneut oder ändere einen Filter, um weitere Dokumente auszuwählen.",
diff --git a/messages/en.json b/messages/en.json
index f42ec1e19..2e3c9feb5 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -6711,7 +6711,7 @@
       "baseUrl": "Address",
       "allowedOrigins": "Allowed on this server: {origins}",
       "organizationId": "Organization id",
-      "organizationHelp": "The part after /organizations/ in the Papra address bar.",
+      "organizationHelp": "The part after /organizations/ in the Papra address bar. Papra organization ids look like org_ followed by 24 letters and digits.",
       "token": "API token",
       "tokenSaved": "Saved for this address. Leave empty to keep it.",
       "tokenHelpPaperless": "In Paperless-ngx: My Profile, API token.",
@@ -10220,7 +10220,7 @@
         "authRefused": "The archive refused the token. Check the token and its permissions.",
         "versionTooOld": "The archive is too old. Paperless-ngx 2.16 or later is needed.",
         "badResponse": "The archive's answer could not be read. Check that the address points at the archive itself.",
-        "notFound": "The archive has no such document, or no such organization.",
+        "notFound": "The archive has no such document, or the organization id is wrong or not yours.",
         "linkTargetNotFound": "The record to link to no longer exists.",
         "rateLimited": "Too many requests. Wait a minute and try again.",
         "browserOnly": "Document archives can only be used in the browser.",
@@ -10233,7 +10233,8 @@
         "uploadLimit": "The hourly upload limit is reached. Try again later.",
         "uploadBusy": "Other uploads are still running. Try again in a moment.",
         "moduleDisabled": "Documents are switched off in Settings.",
-        "generic": "Something went wrong. Try again."
+        "generic": "Something went wrong. Try again.",
+        "permissionMissing": "The Papra key cannot read tags. Give it the tags:read permission."
       },
       "pickMore": "Pick more",
       "finishedHint": "Search again or change a filter to pick more documents.",
diff --git a/messages/es.json b/messages/es.json
index 6f9e5127b..5447d74ba 100644
--- a/messages/es.json
+++ b/messages/es.json
@@ -6711,7 +6711,7 @@
       "baseUrl": "Dirección",
       "allowedOrigins": "Permitido en este servidor: {origins}",
       "organizationId": "Id de organización",
-      "organizationHelp": "La parte que sigue a /organizations/ en la barra de direcciones de Papra.",
+      "organizationHelp": "La parte que sigue a /organizations/ en la barra de direcciones de Papra. Los id de organización de Papra tienen la forma org_ seguida de 24 letras y cifras.",
       "token": "Token de la API",
       "tokenSaved": "Guardado para esta dirección. Déjalo vacío para conservarlo.",
       "tokenHelpPaperless": "En Paperless-ngx: Mi perfil, token de la API.",
@@ -10220,7 +10220,7 @@
         "authRefused": "El archivo rechazó el token. Comprueba el token y sus permisos.",
         "versionTooOld": "El archivo es demasiado antiguo. Se necesita Paperless-ngx 2.16 o posterior.",
         "badResponse": "No se pudo leer la respuesta del archivo. Comprueba que la dirección apunta al propio archivo.",
-        "notFound": "El archivo no tiene ese documento o esa organización.",
+        "notFound": "El archivo no tiene ese documento, o el id de organización es incorrecto o no es tuyo.",
         "linkTargetNotFound": "El registro que se iba a vincular ya no existe.",
         "rateLimited": "Demasiadas solicitudes. Espera un minuto y vuelve a intentarlo.",
         "browserOnly": "Los archivos de documentos solo se pueden usar en el navegador.",
@@ -10233,7 +10233,8 @@
         "uploadLimit": "Se alcanzó el límite de subidas por hora. Inténtalo más tarde.",
         "uploadBusy": "Aún hay otras subidas en curso. Inténtalo en un momento.",
         "moduleDisabled": "Los documentos están desactivados en Ajustes.",
-        "generic": "Algo salió mal. Inténtalo de nuevo."
+        "generic": "Algo salió mal. Inténtalo de nuevo.",
+        "permissionMissing": "La clave de Papra no puede leer etiquetas. Dale el permiso tags:read."
       },
       "pickMore": "Elegir más",
       "finishedHint": "Busca de nuevo o cambia un filtro para elegir más documentos.",
diff --git a/messages/fr.json b/messages/fr.json
index 93f029e4c..e75cca526 100644
--- a/messages/fr.json
+++ b/messages/fr.json
@@ -6711,7 +6711,7 @@
       "baseUrl": "Adresse",
       "allowedOrigins": "Autorisé sur ce serveur : {origins}",
       "organizationId": "Identifiant d'organisation",
-      "organizationHelp": "La partie après /organizations/ dans la barre d'adresse de Papra.",
+      "organizationHelp": "La partie après /organizations/ dans la barre d'adresse de Papra. Les identifiants d'organisation Papra ont la forme org_ suivi de 24 lettres et chiffres.",
       "token": "Jeton d'API",
       "tokenSaved": "Enregistré pour cette adresse. Laissez vide pour le conserver.",
       "tokenHelpPaperless": "Dans Paperless-ngx : Mon profil, jeton d'API.",
@@ -10220,7 +10220,7 @@
         "authRefused": "L'archive a refusé le jeton. Vérifiez le jeton et ses droits.",
         "versionTooOld": "L'archive est trop ancienne. Paperless-ngx 2.16 ou plus récent est nécessaire.",
         "badResponse": "La réponse de l'archive est illisible. Vérifiez que l'adresse pointe vers l'archive elle-même.",
-        "notFound": "L'archive ne connaît pas ce document ou cette organisation.",
+        "notFound": "L'archive ne connaît pas ce document, ou l'identifiant d'organisation est faux ou n'est pas le vôtre.",
         "linkTargetNotFound": "L'élément auquel lier le document n'existe plus.",
         "rateLimited": "Trop de requêtes. Patientez une minute et réessayez.",
         "browserOnly": "Les archives de documents ne s'utilisent que dans le navigateur.",
@@ -10233,7 +10233,8 @@
         "uploadLimit": "La limite horaire d'envois est atteinte. Réessayez plus tard.",
         "uploadBusy": "D'autres envois sont en cours. Réessayez dans un instant.",
         "moduleDisabled": "Les documents sont désactivés dans les réglages.",
-        "generic": "Un problème est survenu. Réessayez."
+        "generic": "Un problème est survenu. Réessayez.",
+        "permissionMissing": "La clé Papra ne peut pas lire les étiquettes. Donnez-lui le droit tags:read."
       },
       "pickMore": "En choisir d'autres",
       "finishedHint": "Cherchez à nouveau ou changez un filtre pour choisir d'autres documents.",
diff --git a/messages/it.json b/messages/it.json
index 23f268c99..802991bbc 100644
--- a/messages/it.json
+++ b/messages/it.json
@@ -6711,7 +6711,7 @@
       "baseUrl": "Indirizzo",
       "allowedOrigins": "Consentito su questo server: {origins}",
       "organizationId": "Id organizzazione",
-      "organizationHelp": "La parte dopo /organizations/ nella barra degli indirizzi di Papra.",
+      "organizationHelp": "La parte dopo /organizations/ nella barra degli indirizzi di Papra. Gli id organizzazione di Papra hanno la forma org_ seguita da 24 lettere e cifre.",
       "token": "Token API",
       "tokenSaved": "Salvato per questo indirizzo. Lascia vuoto per mantenerlo.",
       "tokenHelpPaperless": "In Paperless-ngx: Il mio profilo, token API.",
@@ -10220,7 +10220,7 @@
         "authRefused": "L'archivio ha rifiutato il token. Controlla il token e i suoi permessi.",
         "versionTooOld": "L'archivio è troppo vecchio. Serve Paperless-ngx 2.16 o successivo.",
         "badResponse": "Non è stato possibile leggere la risposta dell'archivio. Verifica che l'indirizzo punti all'archivio stesso.",
-        "notFound": "L'archivio non ha questo documento o questa organizzazione.",
+        "notFound": "L'archivio non ha questo documento, oppure l'id dell'organizzazione è sbagliato o non è tuo.",
         "linkTargetNotFound": "L'elemento da collegare non esiste più.",
         "rateLimited": "Troppe richieste. Attendi un minuto e riprova.",
         "browserOnly": "Gli archivi di documenti si usano solo nel browser.",
@@ -10233,7 +10233,8 @@
         "uploadLimit": "È stato raggiunto il limite orario di caricamenti. Riprova più tardi.",
         "uploadBusy": "Altri caricamenti sono ancora in corso. Riprova tra un momento.",
         "moduleDisabled": "I documenti sono disattivati nelle impostazioni.",
-        "generic": "Qualcosa è andato storto. Riprova."
+        "generic": "Qualcosa è andato storto. Riprova.",
+        "permissionMissing": "La chiave Papra non può leggere le etichette. Dalle il permesso tags:read."
       },
       "pickMore": "Scegline altri",
       "finishedHint": "Cerca di nuovo o cambia un filtro per scegliere altri documenti.",
diff --git a/messages/ko.json b/messages/ko.json
index fef692073..ace3dd8ac 100644
--- a/messages/ko.json
+++ b/messages/ko.json
@@ -6711,7 +6711,7 @@
       "baseUrl": "주소",
       "allowedOrigins": "이 서버에서 허용됨: {origins}",
       "organizationId": "조직 ID",
-      "organizationHelp": "Papra 주소 표시줄에서 /organizations/ 다음 부분입니다.",
+      "organizationHelp": "Papra 주소 표시줄에서 /organizations/ 다음 부분입니다. Papra 조직 ID는 org_ 뒤에 영문자와 숫자 24자가 오는 형식입니다.",
       "token": "API 토큰",
       "tokenSaved": "이 주소에 저장됨. 유지하려면 비워 두세요.",
       "tokenHelpPaperless": "Paperless-ngx: 내 프로필의 API 토큰.",
@@ -10220,7 +10220,7 @@
         "authRefused": "보관함이 토큰을 거부했습니다. 토큰과 권한을 확인하세요.",
         "versionTooOld": "보관함 버전이 너무 오래되었습니다. Paperless-ngx 2.16 이상이 필요합니다.",
         "badResponse": "보관함의 응답을 읽을 수 없습니다. 주소가 보관함 자체를 가리키는지 확인하세요.",
-        "notFound": "보관함에 해당 문서나 조직이 없습니다.",
+        "notFound": "보관함에 해당 문서가 없거나, 조직 ID가 잘못되었거나 본인의 조직이 아닙니다.",
         "linkTargetNotFound": "연결할 기록이 더 이상 존재하지 않습니다.",
         "rateLimited": "요청이 너무 많습니다. 1분 후에 다시 시도하세요.",
         "browserOnly": "문서 보관함은 브라우저에서만 사용할 수 있습니다.",
@@ -10233,7 +10233,8 @@
         "uploadLimit": "시간당 업로드 한도에 도달했습니다. 나중에 다시 시도하세요.",
         "uploadBusy": "다른 업로드가 아직 진행 중입니다. 잠시 후 다시 시도하세요.",
         "moduleDisabled": "설정에서 문서 기능이 꺼져 있습니다.",
-        "generic": "문제가 발생했습니다. 다시 시도하세요."
+        "generic": "문제가 발생했습니다. 다시 시도하세요.",
+        "permissionMissing": "Papra 키가 태그를 읽을 수 없습니다. tags:read 권한을 부여하세요."
       },
       "pickMore": "더 고르기",
       "finishedHint": "다시 검색하거나 필터를 바꿔 문서를 더 고르세요.",
diff --git a/messages/pl.json b/messages/pl.json
index 7cb49c5ae..fef668a57 100644
--- a/messages/pl.json
+++ b/messages/pl.json
@@ -6711,7 +6711,7 @@
       "baseUrl": "Adres",
       "allowedOrigins": "Dozwolone na tym serwerze: {origins}",
       "organizationId": "Identyfikator organizacji",
-      "organizationHelp": "Część po /organizations/ w pasku adresu Papra.",
+      "organizationHelp": "Część po /organizations/ w pasku adresu Papra. Identyfikatory organizacji Papra mają postać org_ i 24 litery oraz cyfry.",
       "token": "Token API",
       "tokenSaved": "Zapisano dla tego adresu. Zostaw puste, aby go zachować.",
       "tokenHelpPaperless": "W Paperless-ngx: Mój profil, token API.",
@@ -10220,7 +10220,7 @@
         "authRefused": "Archiwum odrzuciło token. Sprawdź token i jego uprawnienia.",
         "versionTooOld": "Archiwum jest za stare. Potrzebny jest Paperless-ngx 2.16 lub nowszy.",
         "badResponse": "Nie udało się odczytać odpowiedzi archiwum. Sprawdź, czy adres wskazuje na samo archiwum.",
-        "notFound": "Archiwum nie ma takiego dokumentu ani takiej organizacji.",
+        "notFound": "Archiwum nie ma takiego dokumentu albo identyfikator organizacji jest błędny lub nie należy do ciebie.",
         "linkTargetNotFound": "Wpis, z którym miało nastąpić powiązanie, już nie istnieje.",
         "rateLimited": "Za dużo żądań. Odczekaj minutę i spróbuj ponownie.",
         "browserOnly": "Z archiwów dokumentów można korzystać tylko w przeglądarce.",
@@ -10233,7 +10233,8 @@
         "uploadLimit": "Osiągnięto godzinny limit przesyłania. Spróbuj później.",
         "uploadBusy": "Trwają jeszcze inne przesyłania. Spróbuj za chwilę.",
         "moduleDisabled": "Dokumenty są wyłączone w ustawieniach.",
-        "generic": "Coś poszło nie tak. Spróbuj ponownie."
+        "generic": "Coś poszło nie tak. Spróbuj ponownie.",
+        "permissionMissing": "Klucz Papra nie może odczytać tagów. Nadaj mu uprawnienie tags:read."
       },
       "pickMore": "Wybierz więcej",
       "finishedHint": "Wyszukaj ponownie lub zmień filtr, aby wybrać więcej dokumentów.",
diff --git a/src/components/documents/sources/source-errors.ts b/src/components/documents/sources/source-errors.ts
index 3c1739924..9ec63e293 100644
--- a/src/components/documents/sources/source-errors.ts
+++ b/src/components/documents/sources/source-errors.ts
@@ -22,6 +22,7 @@ export function isStoppingError(code: string | undefined): boolean {
     code === "documents.inbound.rateLimited" ||
     code === "documents.inbound.quotaExceeded" ||
     code === "documents.sources.authRefused" ||
+    code === "documents.sources.permissionMissing" ||
     code === "documents.sources.unreachable" ||
     code === "documents.sources.originNotAllowed" ||
     code === "documents.sources.notConnected" ||
@@ -45,6 +46,8 @@ export function sourceErrorMessage(t: T, code: string | undefined): string {
       return t("documents.sourcePicker.errors.redirected");
     case "documents.sources.authRefused":
       return t("documents.sourcePicker.errors.authRefused");
+    case "documents.sources.permissionMissing":
+      return t("documents.sourcePicker.errors.permissionMissing");
     case "documents.sources.versionTooOld":
       return t("documents.sourcePicker.errors.versionTooOld");
     case "documents.sources.badResponse":
diff --git a/src/lib/documents/sources/__tests__/clients.test.ts b/src/lib/documents/sources/__tests__/clients.test.ts
index 78f4f536b..ed6291335 100644
--- a/src/lib/documents/sources/__tests__/clients.test.ts
+++ b/src/lib/documents/sources/__tests__/clients.test.ts
@@ -41,7 +41,7 @@ const PAPRA = {
   system: "PAPRA" as const,
   origin: "https://papra.example.com",
   baseUrl: "https://papra.example.com",
-  organizationId: "org_123",
+  organizationId: "org_a1b2c3d4e5f6g7h8i9j0k1l2",
   token: "ppk_secret",
 };
 
@@ -383,6 +383,74 @@ describe("Paperless-ngx tags", () => {
   });
 });
 
+describe("Papra, as it answers for real", () => {
+  it("quotes each word so a leading dash is not a negation, and sends the date range", async () => {
+    serve({
+      "/api/organizations/org_a1b2c3d4e5f6g7h8i9j0k1l2/documents": () =>
+        json({ documents: [], documentsCount: 0 }),
+    });
+    await sourceClient(PAPRA).search({
+      q: "-Knie  Entlass",
+      tagId: null,
+      from: "2024-01-01",
+      to: "2024-12-31",
+      page: 1,
+    });
+    const list = calledUrls().find((u) => u.pathname.endsWith("/documents"));
+    expect(list?.searchParams.get("searchQuery")).toBe(
+      '"-Knie" "Entlass" date:>=2024-01-01 date:<=2024-12-31',
+    );
+  });
+
+  it("refuses an organization id Papra would not issue", () => {
+    for (const org of ["org_123", "../admin", "ORG_A1B2C3D4E5F6G7H8I9J0K1L2"]) {
+      expect(() => sourceClient({ ...PAPRA, organizationId: org })).toThrow(
+        DocumentSourceError,
+      );
+    }
+    expect(safeFetch).not.toHaveBeenCalled();
+  });
+
+  it("reads 'not in this organization' and a malformed id as no such organization", async () => {
+    serve({
+      "/api/organizations/": () =>
+        json({ error: { code: "user.not_in_organization" } }, { status: 403 }),
+    });
+    expect(
+      ((await failure(sourceClient(PAPRA).test())) as DocumentSourceError).code,
+    ).toBe("notFound");
+    serve({
+      "/api/organizations/": () =>
+        json(
+          { error: { code: "server.invalid_request.params" } },
+          { status: 400 },
+        ),
+    });
+    expect(
+      ((await failure(sourceClient(PAPRA).test())) as DocumentSourceError).code,
+    ).toBe("notFound");
+    // Any other refusal of the key is still the key.
+    serve({
+      "/api/organizations/": () =>
+        json({ error: { code: "auth.unauthorized" } }, { status: 401 }),
+    });
+    expect(
+      ((await failure(sourceClient(PAPRA).test())) as DocumentSourceError).code,
+    ).toBe("authRefused");
+  });
+
+  it("fails the connection test when the key cannot read tags", async () => {
+    serve({
+      "/api/organizations/org_a1b2c3d4e5f6g7h8i9j0k1l2/tags": () =>
+        json({}, { status: 401 }),
+      "/api/organizations/org_a1b2c3d4e5f6g7h8i9j0k1l2/documents": () =>
+        json({ documents: [], documentsCount: 0 }),
+    });
+    const err = await failure(sourceClient(PAPRA).test());
+    expect((err as DocumentSourceError).code).toBe("permissionMissing");
+  });
+});
+
 describe("Papra", () => {
   const tags = {
     tags: [
@@ -393,8 +461,8 @@ describe("Papra", () => {
 
   it("sends the name and the tag through searchQuery and re-checks both", async () => {
     serve({
-      "/api/organizations/org_123/tags": () => json(tags),
-      "/api/organizations/org_123/documents": () =>
+      "/api/organizations/org_a1b2c3d4e5f6g7h8i9j0k1l2/tags": () => json(tags),
+      "/api/organizations/org_a1b2c3d4e5f6g7h8i9j0k1l2/documents": () =>
         json({
           documentsCount: 60,
           documents: [
@@ -431,7 +499,7 @@ describe("Papra", () => {
     });
     const list = calledUrls().find((u) => u.pathname.endsWith("/documents"));
     expect(list?.searchParams.get("searchQuery")).toBe(
-      'blood tag:"Lab results"',
+      '"blood" tag:"Lab results" date:>=2025-01-01',
     );
     expect(list?.searchParams.get("pageIndex")).toBe("0");
     expect(list?.searchParams.get("pageSize")).toBe("25");
@@ -453,7 +521,9 @@ describe("Papra", () => {
   });
 
   it("matches nothing for a tag that no longer exists", async () => {
-    serve({ "/api/organizations/org_123/tags": () => json(tags) });
+    serve({
+      "/api/organizations/org_a1b2c3d4e5f6g7h8i9j0k1l2/tags": () => json(tags),
+    });
     await expect(
       sourceClient(PAPRA).search({
         q: "",
@@ -469,7 +539,9 @@ describe("Papra", () => {
   });
 
   it("lists tags by name and maps an unknown organization to notFound", async () => {
-    serve({ "/api/organizations/org_123/tags": () => json(tags) });
+    serve({
+      "/api/organizations/org_a1b2c3d4e5f6g7h8i9j0k1l2/tags": () => json(tags),
+    });
     await expect(sourceClient(PAPRA).tags()).resolves.toEqual([
       { id: "tag_a", name: "Health" },
       { id: "tag_b", name: "Lab results" },
@@ -482,9 +554,9 @@ describe("Papra", () => {
 
   it("reads a document and downloads its file", async () => {
     serve({
-      "/api/organizations/org_123/documents/doc_1/file": () =>
-        new Response(new Uint8Array([1, 2, 3])),
-      "/api/organizations/org_123/documents/doc_1": () =>
+      "/api/organizations/org_a1b2c3d4e5f6g7h8i9j0k1l2/documents/doc_1/file":
+        () => new Response(new Uint8Array([1, 2, 3])),
+      "/api/organizations/org_a1b2c3d4e5f6g7h8i9j0k1l2/documents/doc_1": () =>
         json({
           document: {
             id: "doc_1",
diff --git a/src/lib/documents/sources/clients.ts b/src/lib/documents/sources/clients.ts
index a5d1cfa85..33d9371bf 100644
--- a/src/lib/documents/sources/clients.ts
+++ b/src/lib/documents/sources/clients.ts
@@ -30,8 +30,9 @@ import {
   DOCUMENT_PICKER_MAX_TAGS,
   DOCUMENT_PICKER_PAGE_SIZE,
   isSourceDocumentId,
-  PAPRA_ID,
+  PAPRA_ORG_ID,
   type DocumentPickerSystem,
+  type DocumentSourceErrorCode,
   type DocumentSourceTagDto,
 } from "./types";
 
@@ -335,13 +336,33 @@ function paperless(connection: SourceConnection): SourceClient {
 
 // ── Papra ──────────────────────────────────────────────────────────────────
 
+/**
+ * Papra's error bodies carry a machine code. Two of them mean "no such
+ * organization" rather than "wrong key": a valid organization id the key's
+ * user is not a member of (403 `user.not_in_organization`), and one Papra
+ * cannot parse (400 `server.invalid_request.params`).
+ */
+function papraError(
+  status: number,
+  code: string | null,
+): DocumentSourceErrorCode | null {
+  if (status === 403 && code === "user.not_in_organization") return "notFound";
+  if (status === 400 && code === "server.invalid_request.params") {
+    return "notFound";
+  }
+  return null;
+}
+
 /** Papra's search syntax quotes a tag name that holds a space. */
 function papraTagTerm(name: string): string {
   return /[\s"]/.test(name) ? `tag:${JSON.stringify(name)}` : `tag:${name}`;
 }
 
 function papra(connection: SourceConnection): SourceClient {
-  if (!connection.organizationId || !PAPRA_ID.test(connection.organizationId)) {
+  if (
+    !connection.organizationId ||
+    !PAPRA_ORG_ID.test(connection.organizationId)
+  ) {
     throw new DocumentSourceError("notFound");
   }
   const org = `/api/organizations/${encodeURIComponent(connection.organizationId)}`;
@@ -352,6 +373,7 @@ function papra(connection: SourceConnection): SourceClient {
       Authorization: `Bearer ${connection.token}`,
       Accept: "application/json",
     },
+    classify: papraError,
   };
   const download: SourceTarget = {
     ...target,
@@ -384,13 +406,31 @@ function papra(connection: SourceConnection): SourceClient {
         `${org}/documents?pageIndex=0&pageSize=1`,
       );
       if (!asRecord(body)) throw shapeError();
+      // The tag filter needs `tags:read`; a key without it would save green
+      // and then fail on the first search.
+      try {
+        await sourceJson(target, `${org}/tags`);
+      } catch (err) {
+        if (err instanceof DocumentSourceError && err.code === "authRefused") {
+          throw new DocumentSourceError(
+            "permissionMissing",
+            err.upstreamStatus,
+          );
+        }
+        throw err;
+      }
     },
 
     tags: listTags,
 
     async search(params) {
-      const terms: string[] = [];
-      if (params.q) terms.push(params.q);
+      // Each word quoted: Papra reads a leading `-` as a negation and a `:` as
+      // a field, and a quoted word still matches as a prefix.
+      const terms: string[] = params.q
+        .split(/\s+/)
+        .map((word) => word.replace(/"/g, ""))
+        .filter((word) => word.length > 0)
+        .map((word) => `"${word}"`);
       if (params.tagId) {
         const tag = (await listTags()).find((t) => t.id === params.tagId);
         // A tag that no longer exists matches nothing, rather than silently
@@ -398,6 +438,10 @@ function papra(connection: SourceConnection): SourceClient {
         if (!tag) return { items: [], hasMore: false };
         terms.push(papraTagTerm(tag.name));
       }
+      // The range goes to Papra as its own `date:` filter; the check on each
+      // row below stays as the net for a version that reads it differently.
+      if (params.from) terms.push(`date:>=${params.from}`);
+      if (params.to) terms.push(`date:<=${params.to}`);
       const pageIndex = params.page - 1;
       const query = new URLSearchParams({
         pageIndex: String(pageIndex),
diff --git a/src/lib/documents/sources/http.ts b/src/lib/documents/sources/http.ts
index 473d442ea..d5daf1b25 100644
--- a/src/lib/documents/sources/http.ts
+++ b/src/lib/documents/sources/http.ts
@@ -62,6 +62,8 @@ export interface SourceTarget {
   /** Origin plus the optional base path, no trailing slash. */
   baseUrl: string;
   headers: Record<string, string>;
+  /** How this source's error bodies read, when they say more than a status. */
+  classify?: ErrorClassifier;
 }
 
 async function sourceRequest(
@@ -103,13 +105,54 @@ async function discard(response: Response): Promise<void> {
   }
 }
 
+/**
+ * A source-specific reading of an error answer: given the status and the
+ * machine code in the body (if any), the error to report, or null for the
+ * generic mapping. The body itself is never passed on.
+ */
+export type ErrorClassifier = (
+  status: number,
+  code: string | null,
+) => DocumentSourceErrorCode | null;
+
+/** Longest error body read to find its machine code. */
+const ERROR_BODY_MAX_BYTES = 4 * 1024;
+
+/** The `code` (or `error.code`) of a JSON error body, if there is one. */
+async function errorCodeOf(response: Response): Promise<string | null> {
+  try {
+    const bytes = await readBoundedBody(response.body, ERROR_BODY_MAX_BYTES);
+    const body = JSON.parse(new TextDecoder().decode(bytes)) as unknown;
+    if (!body || typeof body !== "object") return null;
+    const record = body as Record<string, unknown>;
+    const nested = record.error as Record<string, unknown> | undefined;
+    const code =
+      typeof record.code === "string"
+        ? record.code
+        : nested &&
+            typeof nested === "object" &&
+            typeof nested.code === "string"
+          ? nested.code
+          : null;
+    return code && code.length <= 100 ? code : null;
+  } catch {
+    return null;
+  }
+}
+
 /** Map a non-2xx answer to the error the person sees. */
 export async function failFor(
   response: Response,
   notFound: DocumentSourceErrorCode = "notFound",
+  classify?: ErrorClassifier,
 ): Promise<never> {
-  await discard(response);
   const status = response.status;
+  if (classify) {
+    const specific = classify(status, await errorCodeOf(response));
+    if (specific) throw new DocumentSourceError(specific, status);
+  } else {
+    await discard(response);
+  }
   if (status === 401 || status === 403) {
     throw new DocumentSourceError("authRefused", status);
   }
@@ -124,10 +167,19 @@ export async function failFor(
 export async function sourceJson(
   target: SourceTarget,
   path: string,
-  options: { notFound?: DocumentSourceErrorCode } = {},
+  options: {
+    notFound?: DocumentSourceErrorCode;
+    classify?: ErrorClassifier;
+  } = {},
 ): Promise<{ body: unknown; response: Response }> {
   const response = await sourceRequest(target, path, SOURCE_JSON_TIMEOUT_MS);
-  if (!response.ok) return failFor(response, options.notFound);
+  if (!response.ok) {
+    return failFor(
+      response,
+      options.notFound,
+      options.classify ?? target.classify,
+    );
+  }
   const declared = Number(response.headers.get("content-length") ?? 0);
   if (declared > SOURCE_JSON_MAX_BYTES) {
     await discard(response);
@@ -162,7 +214,7 @@ export async function sourceDownload(
     path,
     SOURCE_DOWNLOAD_TIMEOUT_MS,
   );
-  if (!response.ok) return failFor(response);
+  if (!response.ok) return failFor(response, "notFound", target.classify);
   const declared = Number(response.headers.get("content-length") ?? 0);
   if (declared > maxFileBytes) {
     await discard(response);
diff --git a/src/lib/documents/sources/route-support.ts b/src/lib/documents/sources/route-support.ts
index a1b9aba86..126144674 100644
--- a/src/lib/documents/sources/route-support.ts
+++ b/src/lib/documents/sources/route-support.ts
@@ -83,6 +83,7 @@ const STATUS: Record<DocumentSourceErrorCode, number> = {
   unreachable: 502,
   redirected: 502,
   authRefused: 502,
+  permissionMissing: 502,
   versionTooOld: 502,
   badResponse: 502,
   notFound: 404,
@@ -99,6 +100,8 @@ const MESSAGE: Record<DocumentSourceErrorCode, string> = {
   redirected:
     "The document archive redirected the request. Use the address it redirects to.",
   authRefused: "The document archive refused the API token.",
+  permissionMissing:
+    "The API key cannot read the archive's tags. Give it the tags:read permission.",
   versionTooOld: "The document archive's version is too old.",
   badResponse: "The document archive gave an answer HealthLog cannot read.",
   notFound: "The document archive has no such document or organization.",
diff --git a/src/lib/documents/sources/types.ts b/src/lib/documents/sources/types.ts
index 6dd8ddf35..3fdbfd1aa 100644
--- a/src/lib/documents/sources/types.ts
+++ b/src/lib/documents/sources/types.ts
@@ -43,8 +43,10 @@ export const DOCUMENT_PICKER_MAX_TAGS = 1000;
 
 /** Paperless-ngx document ids are integers. */
 export const PAPERLESS_ID = /^\d{1,18}$/;
-/** Papra document and organization ids: letters, digits, `_` and `-`. */
+/** Papra document ids: letters, digits, `_` and `-`. */
 export const PAPRA_ID = /^[A-Za-z0-9_-]{1,128}$/;
+/** Papra organization ids, as Papra issues them. */
+export const PAPRA_ORG_ID = /^org_[a-z0-9]{24}$/;
 
 /**
  * Is `id` a document id `system` could have issued? Checked before an id is
@@ -134,6 +136,7 @@ export const DOCUMENT_SOURCE_ERROR_CODES = [
   "documents.sources.unreachable",
   "documents.sources.redirected",
   "documents.sources.authRefused",
+  "documents.sources.permissionMissing",
   "documents.sources.versionTooOld",
   "documents.sources.badResponse",
   "documents.sources.notFound",
diff --git a/src/lib/openapi/error-codes.ts b/src/lib/openapi/error-codes.ts
index f8bbf0e7b..bb300d4ae 100644
--- a/src/lib/openapi/error-codes.ts
+++ b/src/lib/openapi/error-codes.ts
@@ -145,6 +145,7 @@ export const ERROR_CODE_CATALOGUE: Readonly<Record<string, readonly string[]>> =
       "documents.sources.notFound",
       "documents.sources.organizationRequired",
       "documents.sources.originNotAllowed",
+      "documents.sources.permissionMissing",
       "documents.sources.rateLimited",
       "documents.sources.redirected",
       "documents.sources.tokenRequired",
diff --git a/src/lib/openapi/routes/document-sources.ts b/src/lib/openapi/routes/document-sources.ts
index 53f4cfe6f..0b97d283c 100644
--- a/src/lib/openapi/routes/document-sources.ts
+++ b/src/lib/openapi/routes/document-sources.ts
@@ -95,13 +95,13 @@ const refusal = {
 
 const unavailable = {
   description:
-    "`documents.sources.unavailable`: the operator has not listed any origin in `DOCUMENT_SOURCE_ORIGINS`, so the picker is off. `documents.sources.notConnected`: no connection is saved for this system. `documents.sources.notFound`: the source has no such document, or (Papra) no such organization.",
+    "`documents.sources.unavailable`: the operator has not listed any origin in `DOCUMENT_SOURCE_ORIGINS`, so the picker is off. `documents.sources.notConnected`: no connection is saved for this system. `documents.sources.notFound`: the source has no such document, or (Papra) no such organization, including one the key's user is not a member of (Papra 403 `user.not_in_organization`) and one Papra cannot parse (400).",
   content: { "application/json": { schema: errorEnvelope } },
 };
 
 const upstream = {
   description:
-    "The source could not answer usefully, with the reason in `meta.errorCode` and, when the source answered at all, its HTTP status in `meta.upstreamStatus` (its body is never passed on): `documents.sources.unreachable` (no connection, timeout, or a destination refused at dial time), `documents.sources.redirected` (the source answered with a redirect, which is never followed), `documents.sources.authRefused` (401/403 from the source), `documents.sources.versionTooOld` (Paperless-ngx older than 2.16 / API version 9), `documents.sources.badResponse` (not the documented JSON, or larger than 1 MiB).",
+    "The source could not answer usefully, with the reason in `meta.errorCode` and, when the source answered at all, its HTTP status in `meta.upstreamStatus` (its body is never passed on): `documents.sources.unreachable` (no connection, timeout, or a destination refused at dial time), `documents.sources.redirected` (the source answered with a redirect, which is never followed), `documents.sources.authRefused` (401/403 from the source), `documents.sources.permissionMissing` (Papra: the key cannot read tags; needs `tags:read`), `documents.sources.versionTooOld` (Paperless-ngx older than 2.16 / API version 9), `documents.sources.badResponse` (not the documented JSON, or larger than 1 MiB).",
   content: { "application/json": { schema: errorEnvelope } },
 };
 
diff --git a/src/lib/validations/document-sources.ts b/src/lib/validations/document-sources.ts
index d175c601c..4034d4c39 100644
--- a/src/lib/validations/document-sources.ts
+++ b/src/lib/validations/document-sources.ts
@@ -10,7 +10,7 @@ import {
   DOCUMENT_PICKER_LINK_KINDS,
   DOCUMENT_PICKER_MAX_PAGE,
   DOCUMENT_PICKER_QUERY_MAX,
-  PAPRA_ID,
+  PAPRA_ORG_ID,
 } from "@/lib/documents/sources/types";
 import {
   documentSourceIdSchema,
@@ -38,7 +38,7 @@ export const documentSourceSaveSchema = z.object({
   organizationId: z
     .string()
     .trim()
-    .regex(PAPRA_ID, "Expected letters, digits, _ or -")
+    .regex(PAPRA_ORG_ID, "Expected a Papra organization id (org_…)")
     .optional(),
   token: z
     .string()