diff --git a/docs/api/openapi.yaml b/docs/api/openapi.yaml
index 6274c3408..1736800d0 100644
--- a/docs/api/openapi.yaml
+++ b/docs/api/openapi.yaml
@@ -15716,15 +15716,18 @@ paths:
         `sourceId` (its id there, printable, up to 128 characters; needs `sourceSystem`) key the upload. A re-send with
         a known key is a duplicate: 200 with the live row (`meta.duplicate: true`), or, when the owner DELETED that
         document, 200 with `data.deleted: true` and `meta.deleted: true` and nothing stored; this holds after the 30-day
-        purge too. The key may instead ride the query string (`?sourceSystem=…&sourceId=…`): it is then answered before
-        the body is read and before the hourly allowance is charged, so a re-send of a document already held costs
-        neither; a key in both places must agree (else 422). A key that is answered with an existing document by its
-        bytes is remembered for that document, so deleting it keeps that key deleted too. `OTHER` is one shared
-        namespace per account: two different systems both sent as `OTHER` must not reuse each other's ids. An upload
-        answered as a duplicate or as deleted hands its slot of the hourly allowance back. `aiRead=defer` holds back
-        automatic AI reading for this upload: the thumbnail and a local text index still run, the summary and lab
-        staging do not, and the document stays out of the summary catch-up until the person reads it with AI or
-        generates its summary. Absent, behaviour is unchanged.
+        purge too. The key may also ride the query string (`?sourceSystem=…&sourceId=…`): a key the vault already holds
+        is then answered at once, the file is not stored or processed, and the request counts only toward the lookup
+        allowance shared with `GET /api/documents/inbound/source` (5000 an hour per token, per person for a session; 429
+        past it), not toward the hourly upload limit. A key in both places must agree (else 422). Every other upload
+        counts toward the hourly upload limit, duplicates included. A key that is answered with an existing document by
+        its bytes is remembered for that document, so deleting it keeps that key deleted too; one document takes at most
+        20 such keys, beyond which the upload is refused 409 (`documents.inbound.sourceAliasLimit`). `OTHER` is one
+        shared namespace per account: two different systems both sent as `OTHER` must not reuse each other's ids.
+        `aiRead=defer` holds back automatic AI reading for this upload: the thumbnail and a local text index still run,
+        the summary and lab staging do not, and the document stays out of every automatic AI path (the summary catch-up,
+        the automatic index, Index all for search) until the person reads it with AI or generates its summary. Absent,
+        behaviour is unchanged.
 
 
         **Narrow token.** Also reachable with a `documents:write` Bearer (minted at `POST /api/tokens/documents`), which
@@ -15746,8 +15749,9 @@ paths:
               - PAPERLESS
               - PAPRA
               - OTHER
-          description: Import source key, first half. Sent here instead of (or agreeing with) the form field, it is checked before
-            the body is read or the hourly allowance is charged.
+          description: "Import source key, first half. Sent here (and, if also in the form, agreeing with it), a key the vault
+            already holds is answered at once: the file is not stored or processed and the request does not count toward
+            the hourly upload limit, only toward the lookup allowance shared with `GET /api/documents/inbound/source`."
         - name: sourceId
           in: query
           required: false
@@ -15833,7 +15837,13 @@ paths:
               schema:
                 $ref: "#/components/schemas/DocumentUploadEnvelope"
         "401": *a1
-        "409": *a7
+        "409":
+          description: The same bytes are already stored under 20 other import source ids (`documents.inbound.sourceAliasLimit`).
+            Nothing was stored or remembered.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ErrorEnvelope"
         "413":
           description: "Too large: `meta.reason` is `fileTooLarge` (with `maxFileBytes`) or `quotaExceeded` (with `quotaBytes` +
             `usedBytes`)."
@@ -15860,8 +15870,8 @@ paths:
         `known`, the document `id` (null once a deleted document was purged), and whether the owner `deleted` it. Checks
         the document's own key, keys remembered for it when an import sent the same bytes under another key, and the
         keys of purged documents. Reachable with a `documents:write` Bearer (the scope's second and last route) or a
-        cookie session; stores nothing. 5000 lookups an hour per token (per person for a session); gated on the
-        `inboundDocuments` module."
+        cookie session; stores nothing. 5000 lookups an hour per token (per person for a session), shared with the
+        upload's query-string key check; gated on the `inboundDocuments` module."
       parameters:
         - name: sourceSystem
           in: query
@@ -30816,21 +30826,22 @@ components:
                 documents.inbound.invalidUpdate, documents.inbound.localOcrDisabled, documents.inbound.notFound,
                 documents.inbound.notIndexed, documents.inbound.pdfNeedsAnthropic,
                 documents.inbound.providerUnsupported, documents.inbound.quotaExceeded, documents.inbound.rateLimited,
-                documents.inbound.restoreDuplicate, documents.inbound.restoreGone, documents.inbound.uploadBusy,
-                documents.inbound.uploadTimeout, documents.inbound.vaccinationNotFound; 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 — ingest.rate_limited; insights — insights.generate.budgetExceeded,
-                insights.generate.outboundScreened, insights.generate.profileScopeChanged,
-                insights.generate.scopeChanged; labs — labs.biomarker.create.invalid, labs.biomarker.duplicate,
-                labs.biomarker.notFound, labs.biomarker.update.invalid, labs.biomarker.update.referenceRangeInvalid,
-                labs.create.invalid, labs.ocr.budgetExceeded, labs.ocr.extractFailed, labs.ocr.fileTooLarge,
-                labs.ocr.fileType, labs.ocr.localOcrDisabled, labs.ocr.pdfNeedsAnthropic, labs.ocr.providerUnsupported,
+                documents.inbound.restoreDuplicate, documents.inbound.restoreGone, documents.inbound.sourceAliasLimit,
+                documents.inbound.uploadBusy, documents.inbound.uploadTimeout, documents.inbound.vaccinationNotFound;
+                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 —
+                ingest.rate_limited; insights — insights.generate.budgetExceeded, insights.generate.outboundScreened,
+                insights.generate.profileScopeChanged, insights.generate.scopeChanged; labs —
+                labs.biomarker.create.invalid, labs.biomarker.duplicate, labs.biomarker.notFound,
+                labs.biomarker.update.invalid, labs.biomarker.update.referenceRangeInvalid, labs.create.invalid,
+                labs.ocr.budgetExceeded, labs.ocr.extractFailed, labs.ocr.fileTooLarge, labs.ocr.fileType,
+                labs.ocr.localOcrDisabled, labs.ocr.pdfNeedsAnthropic, labs.ocr.providerUnsupported,
                 labs.ocr.rateLimited, labs.restore.invalid, labs.result.notFound, labs.update.invalid,
                 labs.update.linkedFieldsImmutable, labs.update.numericExpected, labs.update.qualitativeExpected,
                 labs.update.referenceRangeInvalid, labs.update.sourceReferenceRangeInvalid; managed_profile —
diff --git a/scripts/__tests__/import-documents.test.ts b/scripts/__tests__/import-documents.test.ts
index c547945be..4117e1048 100644
--- a/scripts/__tests__/import-documents.test.ts
+++ b/scripts/__tests__/import-documents.test.ts
@@ -90,6 +90,8 @@ async function healthlog(
     noLookup?: boolean;
     /** The address redirects elsewhere (http → https, a moved host). */
     redirect?: string;
+    /** Lookups are spent: every lookup answers 429 with a long Retry-After. */
+    lookup429?: boolean;
   } = {},
 ) {
   const stored = new Set<string>();
@@ -110,6 +112,13 @@ async function healthlog(
       !opts.noLookup
     ) {
       lookups.push(queryKey);
+      if (opts.lookup429) {
+        return {
+          status: 429,
+          headers: { "retry-after": "3600" },
+          json: { data: null, error: "Too many lookups." },
+        };
+      }
       const deleted = opts.deleted?.includes(queryKey) ?? false;
       const known = deleted || stored.has(queryKey);
       return {
@@ -158,9 +167,17 @@ async function healthlog(
         size = v.size;
       }
     }
-    // The key rides the query string, where HealthLog reads it first.
-    fields.sourceSystem = url.searchParams.get("sourceSystem") ?? "";
-    fields.sourceId = url.searchParams.get("sourceId") ?? "";
+    // The key rides the query string, where HealthLog reads it first, and
+    // the form; HealthLog refuses the two disagreeing.
+    if (
+      fields.sourceSystem !== url.searchParams.get("sourceSystem") ||
+      fields.sourceId !== url.searchParams.get("sourceId")
+    ) {
+      return {
+        status: 422,
+        json: { data: null, error: "source key mismatch" },
+      };
+    }
     received.push({ auth: req.headers.authorization, fields, filename, size });
     const key = queryKey;
     if (opts.tooLarge?.includes(key)) {
@@ -546,6 +563,28 @@ describe("import-documents.mjs — edges", () => {
     expect(res.stdout).toMatch(/Imported: 2/);
   });
 
+  it("does not wait on spent lookups: the keyed upload answers instead", async () => {
+    const hl = await healthlog({ lookup429: true });
+    const pl = await paperless();
+    const started = Date.now();
+    const res = await runScript(
+      [
+        "paperless",
+        "--paperless-url",
+        pl.url,
+        "--healthlog-url",
+        hl.url,
+        "--tag",
+        "HealthLog",
+      ],
+      env,
+    );
+    expect(res.code).toBe(0);
+    expect(res.stdout).toMatch(/Imported: 2/);
+    // A Retry-After of an hour was not honoured for a lookup.
+    expect(Date.now() - started).toBeLessThan(20_000);
+  });
+
   it("stops on a redirecting HealthLog address and names where it points", async () => {
     const hl = await healthlog({ redirect: "https://health.example" });
     const pl = await paperless();
diff --git a/scripts/import-documents.mjs b/scripts/import-documents.mjs
index 06f679248..307247b35 100644
--- a/scripts/import-documents.mjs
+++ b/scripts/import-documents.mjs
@@ -201,7 +201,7 @@ function retryAfterSeconds(response, fallback) {
  * service pacing us), a 5xx or a dropped connection is retried a few times
  * with a growing pause, and anything else is returned to the caller.
  */
-async function request(label, url, init, makeBody) {
+async function request(label, url, init, makeBody, { waitOn429 = true } = {}) {
   let transient = 0;
   for (;;) {
     let response;
@@ -218,7 +218,7 @@ async function request(label, url, init, makeBody) {
       await wait(TRANSIENT_BACKOFF_MS[transient++], `${label} did not answer`);
       continue;
     }
-    if (response.status === 429) {
+    if (response.status === 429 && waitOn429) {
       await response.arrayBuffer().catch(() => {});
       const seconds = retryAfterSeconds(response, 60);
       await wait(seconds * 1000, `${label} asked to slow down`);
@@ -569,12 +569,20 @@ function stopOnRefusal(response, body, url) {
  */
 async function lookup(options, source, doc) {
   const url = `${options.healthlogUrl}/api/documents/inbound/source?${keyQuery(source, doc)}`;
-  const response = await request("HealthLog", url, {
-    headers: {
-      Authorization: `Bearer ${options.healthlogToken}`,
-      Accept: "application/json",
+  // Not worth waiting for: if the lookups are spent, the upload with the key
+  // answers the same question.
+  const response = await request(
+    "HealthLog",
+    url,
+    {
+      headers: {
+        Authorization: `Bearer ${options.healthlogToken}`,
+        Accept: "application/json",
+      },
     },
-  });
+    undefined,
+    { waitOn429: false },
+  );
   const body = await readBody(response);
   stopOnRefusal(response, body, url);
   if (!response.ok || !body?.data?.known) return null;
@@ -603,6 +611,9 @@ async function upload(options, source, doc, file) {
       if (doc.date) form.append("documentDate", doc.date);
       if (kind) form.append("kind", kind);
       if (!options.aiRead) form.append("aiRead", "defer");
+      // In the form as well as the address; HealthLog checks they agree.
+      form.append("sourceSystem", source.system);
+      form.append("sourceId", doc.sourceId.slice(0, SOURCE_ID_MAX));
       return form;
     },
   );
@@ -789,8 +800,7 @@ function printSummary(options, tally, listed, totalBytes, unknownSizes) {
   if (!options.dryRun && tally.imported > 0 && !options.aiRead) {
     out(
       `${tally.imported} document(s) imported without automatic AI reading. ` +
-        "To have one read, open it in HealthLog and choose Read with AI or Generate summary; " +
-        "Documents > Index all for search reads the ones that had no text to search.",
+        "To have one read, open it in HealthLog and choose Read with AI or Generate summary.",
     );
   }
 }
diff --git a/src/app/api/documents/inbound/__tests__/route.test.ts b/src/app/api/documents/inbound/__tests__/route.test.ts
index 8bb21a712..bcb479701 100644
--- a/src/app/api/documents/inbound/__tests__/route.test.ts
+++ b/src/app/api/documents/inbound/__tests__/route.test.ts
@@ -56,6 +56,7 @@ vi.mock("@/lib/db", () => {
       documentSourceAlias: {
         findUnique: vi.fn(),
         createMany: vi.fn(),
+        count: vi.fn(),
       },
       extractedFact: {
         groupBy: vi.fn(),
@@ -247,6 +248,7 @@ beforeEach(() => {
   vi.mocked(prisma.documentSourceAlias.createMany).mockResolvedValue({
     count: 1,
   } as never);
+  vi.mocked(prisma.documentSourceAlias.count).mockResolvedValue(0 as never);
   // No settings row / no user override → policy defaults (25 MiB / 1 GiB).
   vi.mocked(prisma.appSettings.findUnique).mockResolvedValue(null as never);
   vi.mocked(prisma.user.findUnique).mockResolvedValue(null as never);
@@ -844,7 +846,28 @@ describe("POST /api/documents/inbound — document import", () => {
     );
     expect(res.status).toBe(200);
     expect((await res.json()).data).toEqual({ id: "doc-src", duplicate: true });
-    expect(checkRateLimit).not.toHaveBeenCalled();
+    // Metered on the lookup bucket only; no upload slot is spent.
+    expect(
+      vi.mocked(checkRateLimit).mock.calls.map((c) => [c[0], c[1]]),
+    ).toEqual([["documents-source:token:tok-1", 5000]]);
+  });
+
+  it("429s the query-string check once the lookup bucket is spent", async () => {
+    armToken([DOCUMENTS_WRITE_SCOPE]);
+    vi.mocked(checkRateLimit).mockResolvedValueOnce({
+      allowed: false,
+      remaining: 0,
+      limit: 5000,
+      resetAt: Date.now() + 60_000,
+    } as never);
+    const res = await post(
+      new Request(
+        "http://localhost/api/documents/inbound?sourceSystem=PAPRA&sourceId=doc_1",
+        { method: "POST", body: "x" },
+      ),
+    );
+    expect(res.status).toBe(429);
+    expect(prisma.inboundDocument.findFirst).not.toHaveBeenCalled();
   });
 
   it("422s half a query-string key", async () => {
@@ -871,7 +894,7 @@ describe("POST /api/documents/inbound — document import", () => {
     expect(txCreate).not.toHaveBeenCalled();
   });
 
-  it("remembers the key when keyed bytes are already stored, and refunds the slot", async () => {
+  it("remembers the key when keyed bytes are already stored, and keeps the slot charged", async () => {
     // Own-key lookup misses; the content lookup finds a live row.
     vi.mocked(prisma.inboundDocument.findFirst)
       .mockResolvedValueOnce(null as never)
@@ -891,10 +914,27 @@ describe("POST /api/documents/inbound — document import", () => {
       ],
       skipDuplicates: true,
     });
-    expect(refundRateLimit).toHaveBeenCalledWith("documents-upload:user-1");
+    // The body was read: the slot stays spent, so the same bytes under id
+    // after id are not free.
+    expect(refundRateLimit).not.toHaveBeenCalled();
     expect(txCreate).not.toHaveBeenCalled();
   });
 
+  it("refuses a further id for bytes already held under the maximum", async () => {
+    vi.mocked(prisma.inboundDocument.findFirst)
+      .mockResolvedValueOnce(null as never)
+      .mockResolvedValueOnce(docRow({ id: "doc-manual" }) as never);
+    vi.mocked(prisma.documentSourceAlias.count).mockResolvedValue(20 as never);
+    const res = await post(
+      mkUpload({ sourceSystem: "PAPRA", sourceId: "doc_21" }),
+    );
+    expect(res.status).toBe(409);
+    expect((await res.json()).meta.errorCode).toBe(
+      "documents.inbound.sourceAliasLimit",
+    );
+    expect(prisma.documentSourceAlias.createMany).not.toHaveBeenCalled();
+  });
+
   it("resolves a key held as an alias of a deleted document to deleted", async () => {
     vi.mocked(prisma.documentSourceAlias.findUnique).mockResolvedValue({
       document: docRow({ id: "doc-gone", deletedAt: new Date() }),
@@ -908,22 +948,18 @@ describe("POST /api/documents/inbound — document import", () => {
       duplicate: true,
       deleted: true,
     });
-    expect(refundRateLimit).toHaveBeenCalled();
+    expect(refundRateLimit).not.toHaveBeenCalled();
     expect(txCreate).not.toHaveBeenCalled();
   });
 
-  it("refunds the slot on a plain content duplicate", async () => {
+  it("keeps a plain content duplicate charged and writes no alias", async () => {
     vi.mocked(prisma.inboundDocument.findFirst).mockResolvedValue(
       docRow({ id: "doc-existing" }) as never,
     );
     await post(mkUpload());
-    expect(refundRateLimit).toHaveBeenCalledWith("documents-upload:user-1");
-    expect(prisma.documentSourceAlias.createMany).not.toHaveBeenCalled();
-  });
-
-  it("does not refund a stored upload", async () => {
-    await post(mkUpload());
+    expect(checkRateLimit).toHaveBeenCalledTimes(1);
     expect(refundRateLimit).not.toHaveBeenCalled();
+    expect(prisma.documentSourceAlias.createMany).not.toHaveBeenCalled();
   });
 
   it("persists the deferral on the row", async () => {
diff --git a/src/app/api/documents/inbound/reindex/__tests__/route.test.ts b/src/app/api/documents/inbound/reindex/__tests__/route.test.ts
index d975d002c..bcb3dc018 100644
--- a/src/app/api/documents/inbound/reindex/__tests__/route.test.ts
+++ b/src/app/api/documents/inbound/reindex/__tests__/route.test.ts
@@ -114,11 +114,16 @@ describe("POST /api/documents/inbound/reindex", () => {
 
   it("scopes both counts to the caller's LIVE documents (the gauge's own figures)", async () => {
     await POST(req() as never);
+    // Imports held back from AI reading (#1038) are not part of the run and
+    // stay out of both figures.
     expect(prisma.inboundDocument.count).toHaveBeenCalledWith({
-      where: { userId: "user-1", deletedAt: null },
+      where: { userId: "user-1", deletedAt: null, aiReadDeferred: false },
     });
     expect(prisma.documentContentIndex.count).toHaveBeenCalledWith({
-      where: { userId: "user-1", document: { deletedAt: null } },
+      where: {
+        userId: "user-1",
+        document: { deletedAt: null, aiReadDeferred: false },
+      },
     });
   });
 });
diff --git a/src/app/api/documents/inbound/reindex/route.ts b/src/app/api/documents/inbound/reindex/route.ts
index b5a60d403..5002aa2af 100644
--- a/src/app/api/documents/inbound/reindex/route.ts
+++ b/src/app/api/documents/inbound/reindex/route.ts
@@ -67,11 +67,16 @@ export const POST = apiHandler(async (request) => {
   let enqueued = 0;
   if (jobCreated) {
     const [indexedCount, totalCount] = await Promise.all([
+      // Imports held back from AI reading (#1038) are not part of this run
+      // and are left out of both figures.
       prisma.documentContentIndex.count({
-        where: { userId: user.id, document: { deletedAt: null } },
+        where: {
+          userId: user.id,
+          document: { deletedAt: null, aiReadDeferred: false },
+        },
       }),
       prisma.inboundDocument.count({
-        where: { userId: user.id, deletedAt: null },
+        where: { userId: user.id, deletedAt: null, aiReadDeferred: false },
       }),
     ]);
     enqueued = Math.max(0, totalCount - indexedCount);
diff --git a/src/app/api/documents/inbound/route.ts b/src/app/api/documents/inbound/route.ts
index e07b9c2df..70097db7b 100644
--- a/src/app/api/documents/inbound/route.ts
+++ b/src/app/api/documents/inbound/route.ts
@@ -70,6 +70,7 @@ import { enqueueDocumentSummary } from "@/lib/jobs/document-summary";
 import { enqueueDocumentThumbnail } from "@/lib/jobs/document-thumbnail";
 import { DOCUMENTS_WRITE_SCOPE } from "@/lib/documents/scopes";
 import {
+  checkSourceLookupRateLimit,
   findSourceKey,
   rememberSourceAlias,
   type SourceKeyMatch,
@@ -86,11 +87,7 @@ import { linkTargets } from "@/lib/links";
 import { annotate } from "@/lib/logging/context";
 import { requireModuleEnabled } from "@/lib/modules/gate";
 import { isP2002 } from "@/lib/prisma-errors";
-import {
-  checkRateLimit,
-  rateLimitHeaders,
-  refundRateLimit,
-} from "@/lib/rate-limit";
+import { checkRateLimit, rateLimitHeaders } from "@/lib/rate-limit";
 import {
   documentCreateSchema,
   documentListQuerySchema,
@@ -203,6 +200,19 @@ function deletedResponse(ctx: UploadContext, id: string | null): NextResponse {
   return receiptResponse(id, 200, { duplicate: true, deleted: true });
 }
 
+/**
+ * The same bytes have already been sent under too many source keys
+ * (`MAX_SOURCE_ALIASES_PER_DOCUMENT`). A conflict with what is stored, not a
+ * rate: nothing is remembered and nothing stored.
+ */
+function aliasLimitResponse(): NextResponse {
+  return apiError(
+    "This file is already stored under too many source ids.",
+    409,
+    { errorCode: "documents.inbound.sourceAliasLimit" },
+  );
+}
+
 /** Answer a source key that is already held: duplicate, or deleted. */
 function answerSourceKey(
   ctx: UploadContext,
@@ -307,6 +317,22 @@ async function processUpload(
       );
     }
     queryKey = parsedKey.data;
+    // Metered like the lookup route, on the same bucket: the check stores
+    // nothing and costs no upload slot, but it is not a free oracle either.
+    const lookupRl = await checkSourceLookupRateLimit(
+      scoped,
+      auth.session.id,
+      user.id,
+    );
+    if (!lookupRl.allowed) {
+      const response = apiError("Too many lookups. Try again later.", 429, {
+        errorCode: "documents.inbound.rateLimited",
+      });
+      for (const [k, v] of Object.entries(rateLimitHeaders(lookupRl))) {
+        response.headers.set(k, v);
+      }
+      return response;
+    }
     const match = await findSourceKey(
       user.id,
       queryKey.sourceSystem,
@@ -337,11 +363,10 @@ async function processUpload(
     scoped ? resolveDocumentUploadLimitPerHour() : UPLOAD_LIMIT_PER_HOUR,
     UPLOAD_WINDOW_MS,
   );
-  // A slot pays for a document stored. An upload that turns out to be one
-  // already held (same key, same bytes) hands its slot back, so re-sends —
-  // a Paperless workflow firing on every edit, a re-run over an archive —
-  // never eat into the allowance.
-  const refundSlot = () => refundRateLimit(bucketKey).catch(() => {});
+  // Every upload that reaches the body pays its slot, stored or not. The cheap
+  // way to re-send is the query-string key above, answered before this line;
+  // handing slots back after a full body read would let a leaked token send
+  // the same bytes under id after id for free.
   if (!rl.allowed) {
     const response = apiError("Too many uploads. Try again later.", 429, {
       errorCode: "documents.inbound.rateLimited",
@@ -452,10 +477,7 @@ async function processUpload(
   // the ledger remembers.
   if (sourceSystem && sourceId && !queryKey) {
     const match = await findSourceKey(user.id, sourceSystem, sourceId);
-    if (match) {
-      await refundSlot();
-      return answerSourceKey(ctx, match);
-    }
+    if (match) return answerSourceKey(ctx, match);
   }
 
   let buffer: Buffer;
@@ -522,9 +544,14 @@ async function processUpload(
     // none) is answered with that document — and the key is remembered for
     // it, so once the person deletes the document this key stays deleted too.
     if (sourceSystem && sourceId) {
-      await rememberSourceAlias(user.id, existing.id, sourceSystem, sourceId);
+      const remembered = await rememberSourceAlias(
+        user.id,
+        existing.id,
+        sourceSystem,
+        sourceId,
+      );
+      if (remembered === "limit") return aliasLimitResponse();
     }
-    await refundSlot();
     return duplicateResponse(ctx, existing);
   }
 
@@ -626,10 +653,7 @@ async function processUpload(
       // paths above would have.
       if (sourceSystem && sourceId) {
         const match = await findSourceKey(user.id, sourceSystem, sourceId);
-        if (match) {
-          await refundSlot();
-          return answerSourceKey(ctx, match);
-        }
+        if (match) return answerSourceKey(ctx, match);
       }
       const winner = await prisma.inboundDocument.findFirst({
         where: { userId: user.id, contentSha256, deletedAt: null },
@@ -637,9 +661,14 @@ async function processUpload(
       });
       if (winner) {
         if (sourceSystem && sourceId) {
-          await rememberSourceAlias(user.id, winner.id, sourceSystem, sourceId);
+          const remembered = await rememberSourceAlias(
+            user.id,
+            winner.id,
+            sourceSystem,
+            sourceId,
+          );
+          if (remembered === "limit") return aliasLimitResponse();
         }
-        await refundSlot();
         return duplicateResponse(ctx, winner);
       }
     }
diff --git a/src/app/api/documents/inbound/source/route.ts b/src/app/api/documents/inbound/source/route.ts
index bdc22cc83..caada8b66 100644
--- a/src/app/api/documents/inbound/source/route.ts
+++ b/src/app/api/documents/inbound/source/route.ts
@@ -20,22 +20,17 @@ import {
   sanitiseZodIssues,
 } from "@/lib/api-response";
 import { DOCUMENTS_WRITE_SCOPE } from "@/lib/documents/scopes";
-import { findSourceKey } from "@/lib/documents/source-key";
+import {
+  checkSourceLookupRateLimit,
+  findSourceKey,
+} from "@/lib/documents/source-key";
 import { annotate } from "@/lib/logging/context";
 import { requireModuleEnabled } from "@/lib/modules/gate";
-import { checkRateLimit, rateLimitHeaders } from "@/lib/rate-limit";
+import { rateLimitHeaders } from "@/lib/rate-limit";
 import { documentSourceKeySchema } from "@/lib/validations/inbound-documents";
 
 export const dynamic = "force-dynamic";
 
-/**
- * Lookups per caller per hour. Generous on purpose: an importer asks once per
- * document in the source, so a re-sync of a few thousand documents has to fit
- * in an hour. A lookup reads three indexed rows and stores nothing.
- */
-const LOOKUP_LIMIT_PER_HOUR = 5000;
-const LOOKUP_WINDOW_MS = 60 * 60 * 1000;
-
 export const GET = apiHandler(async (request: Request) => {
   const auth = await requireAuth(DOCUMENTS_WRITE_SCOPE);
   const { user } = auth;
@@ -43,12 +38,10 @@ export const GET = apiHandler(async (request: Request) => {
   const gate = await requireModuleEnabled(user.id, "inboundDocuments");
   if (!gate.enabled) return gate.response;
 
-  const rl = await checkRateLimit(
-    isScopedCredential(auth)
-      ? `documents-source:token:${auth.session.id}`
-      : `documents-source:${user.id}`,
-    LOOKUP_LIMIT_PER_HOUR,
-    LOOKUP_WINDOW_MS,
+  const rl = await checkSourceLookupRateLimit(
+    isScopedCredential(auth),
+    auth.session.id,
+    user.id,
   );
   if (!rl.allowed) {
     const response = apiError("Too many lookups. Try again later.", 429, {
diff --git a/src/lib/documents/__tests__/index-document.test.ts b/src/lib/documents/__tests__/index-document.test.ts
index 40fb7409d..1a06e6d38 100644
--- a/src/lib/documents/__tests__/index-document.test.ts
+++ b/src/lib/documents/__tests__/index-document.test.ts
@@ -169,6 +169,21 @@ describe("indexDocumentContent — provider-first path", () => {
 });
 
 describe("indexDocumentContent — local fallback path", () => {
+  it("a deferred row stays local even when the job did not ask for it", async () => {
+    // #1038 — the row decides: an automatic index of a deferred document
+    // never reaches a provider, whichever path enqueued it.
+    vi.mocked(loadOwnedDocument).mockResolvedValue({
+      ...DOC,
+      aiReadDeferred: true,
+    } as never);
+    vi.mocked(resolveDocumentVisionProvider).mockResolvedValue(PICK as never);
+    visionOk();
+    const outcome = await indexDocumentContent("user-1", "doc-1");
+    expect(outcome).toMatchObject({ indexed: true, source: "local-pdf" });
+    expect(resolveDocumentVisionProvider).not.toHaveBeenCalled();
+    expect(transcribeDocument).not.toHaveBeenCalled();
+  });
+
   it("a deferred import stays local even with an external pick and the toggle ON", async () => {
     // #1038 — `aiRead=defer`: the person asked for AI reading to wait.
     vi.mocked(resolveDocumentVisionProvider).mockResolvedValue(PICK as never);
diff --git a/src/lib/documents/ai-route-support.ts b/src/lib/documents/ai-route-support.ts
index 49cf6a6fb..5a903e484 100644
--- a/src/lib/documents/ai-route-support.ts
+++ b/src/lib/documents/ai-route-support.ts
@@ -113,6 +113,11 @@ export interface LoadedDocument {
   contentCodec: string;
   mimeType: string;
   status: string;
+  /**
+   * The import asked for `aiRead=defer` (#1038). Automatic paths read the
+   * document locally only while it is set.
+   */
+  aiReadDeferred: boolean;
 }
 
 /** Load one live, owner-scoped document with the columns the AI actions need. */
@@ -129,6 +134,7 @@ export async function loadOwnedDocument(
       contentCodec: true,
       mimeType: true,
       status: true,
+      aiReadDeferred: true,
     },
   });
 }
diff --git a/src/lib/documents/index-document.ts b/src/lib/documents/index-document.ts
index faf8e984e..9674b2e1d 100644
--- a/src/lib/documents/index-document.ts
+++ b/src/lib/documents/index-document.ts
@@ -388,17 +388,20 @@ export async function indexDocumentContent(
   const document = await loadOwnedDocument(userId, documentId);
   if (!document) return { indexed: false, reason: "not-found" };
   // v1.39.2 (#1038) — an import that asked for `aiRead=defer` gets the
-  // provider-free text layer only. An empty context is the same shape "no
-  // provider configured" already produces, so the tree falls straight to the
-  // local path without resolving a chain it would not use.
-  const provider: ResolvedIndexProvider = options.localOnly
-    ? {
-        chain: [],
-        pick: null,
-        consentOk: false,
-        dailyCap: 0,
-        costOwner: "operator",
-      }
-    : await resolveIndexProvider(userId);
+  // provider-free text layer only. The row decides, not only the job that
+  // asked: any automatic index of a deferred document stays local until the
+  // person reads it with AI themselves. An empty context is the same shape
+  // "no provider configured" already produces, so the tree falls straight to
+  // the local path without resolving a chain it would not use.
+  const provider: ResolvedIndexProvider =
+    options.localOnly || document.aiReadDeferred
+      ? {
+          chain: [],
+          pick: null,
+          consentOk: false,
+          dailyCap: 0,
+          costOwner: "operator",
+        }
+      : await resolveIndexProvider(userId);
   return indexLoadedDocument(userId, document, provider);
 }
diff --git a/src/lib/documents/source-key.ts b/src/lib/documents/source-key.ts
index 0ce97c450..0c5656f5b 100644
--- a/src/lib/documents/source-key.ts
+++ b/src/lib/documents/source-key.ts
@@ -15,6 +15,7 @@
  * route both ask here, so they cannot disagree about what a key means.
  */
 import { prisma } from "@/lib/db";
+import { checkRateLimit, type RateLimitResult } from "@/lib/rate-limit";
 import type { DocumentSourceSystemValue } from "@/lib/validations/inbound-documents";
 import type { SerialisableDocument } from "@/lib/documents/store";
 
@@ -54,6 +55,14 @@ export async function findSourceKey(
   return purged ? { state: "deleted", id: null } : null;
 }
 
+/**
+ * How many further keys one document may collect. Real archives hold a file
+ * under one or two ids; the cap stops a leaked token from growing the table
+ * by sending the same bytes under id after id. Past it the upload is refused
+ * (409) rather than answered without remembering the key.
+ */
+export const MAX_SOURCE_ALIASES_PER_DOCUMENT = 20;
+
 /**
  * Remember that `sourceId` in `sourceSystem` was answered with `documentId`
  * (same bytes, stored earlier). Without this the key would be forgotten, and
@@ -65,9 +74,36 @@ export async function rememberSourceAlias(
   documentId: string,
   sourceSystem: DocumentSourceSystemValue,
   sourceId: string,
-): Promise<void> {
-  await prisma.documentSourceAlias.createMany({
+): Promise<"remembered" | "known" | "limit"> {
+  const held = await prisma.documentSourceAlias.count({
+    where: { userId, documentId },
+  });
+  if (held >= MAX_SOURCE_ALIASES_PER_DOCUMENT) return "limit";
+  const { count } = await prisma.documentSourceAlias.createMany({
     data: [{ userId, documentId, sourceSystem, sourceId }],
     skipDuplicates: true,
   });
+  return count > 0 ? "remembered" : "known";
+}
+
+/**
+ * Lookups of a source key per caller per hour, shared by the lookup route and
+ * the upload's query-string check so neither is an unmetered way to ask.
+ * Generous: an importer asks once per document, and a re-sync of a few
+ * thousand documents has to fit in an hour. Keyed on the token for a
+ * `documents:write` caller, on the person otherwise.
+ */
+const SOURCE_LOOKUP_LIMIT_PER_HOUR = 5000;
+const SOURCE_LOOKUP_WINDOW_MS = 60 * 60 * 1000;
+
+export function checkSourceLookupRateLimit(
+  scoped: boolean,
+  tokenId: string,
+  userId: string,
+): Promise<RateLimitResult> {
+  return checkRateLimit(
+    scoped ? `documents-source:token:${tokenId}` : `documents-source:${userId}`,
+    SOURCE_LOOKUP_LIMIT_PER_HOUR,
+    SOURCE_LOOKUP_WINDOW_MS,
+  );
 }
diff --git a/src/lib/jobs/__tests__/document-content-index-backfill.test.ts b/src/lib/jobs/__tests__/document-content-index-backfill.test.ts
index ca33cee73..189bcc9b9 100644
--- a/src/lib/jobs/__tests__/document-content-index-backfill.test.ts
+++ b/src/lib/jobs/__tests__/document-content-index-backfill.test.ts
@@ -270,6 +270,10 @@ describe("runContentIndexBackfillForUser", () => {
       reason: "ok",
     });
     expect(upsertContentIndex).toHaveBeenCalledTimes(2);
+    // Imports held back from AI reading (#1038) are never candidates.
+    expect(
+      vi.mocked(prisma.inboundDocument.findMany).mock.calls[0]?.[0]?.where,
+    ).toMatchObject({ aiReadDeferred: false });
   });
 
   it("includes PDFs as candidates for an image-input provider and rasterises them", async () => {
diff --git a/src/lib/jobs/document-content-index-backfill.ts b/src/lib/jobs/document-content-index-backfill.ts
index 17b616348..2dc1bceb9 100644
--- a/src/lib/jobs/document-content-index-backfill.ts
+++ b/src/lib/jobs/document-content-index-backfill.ts
@@ -231,6 +231,9 @@ export async function runContentIndexBackfillForUser(
         deletedAt: null,
         mimeType: { in: candidateMimes },
         contentIndex: { is: null },
+        // An import held back from AI reading (#1038) is read only when the
+        // person opens it and asks; "index all" leaves it local.
+        aiReadDeferred: false,
       },
       select: { id: true },
       orderBy: { id: "asc" },
diff --git a/src/lib/openapi/error-codes.ts b/src/lib/openapi/error-codes.ts
index f899f226c..92602141d 100644
--- a/src/lib/openapi/error-codes.ts
+++ b/src/lib/openapi/error-codes.ts
@@ -132,6 +132,7 @@ export const ERROR_CODE_CATALOGUE: Readonly<Record<string, readonly string[]>> =
       "documents.inbound.rateLimited",
       "documents.inbound.restoreDuplicate",
       "documents.inbound.restoreGone",
+      "documents.inbound.sourceAliasLimit",
       "documents.inbound.uploadBusy",
       "documents.inbound.uploadTimeout",
       "documents.inbound.vaccinationNotFound",
diff --git a/src/lib/openapi/routes/documents.ts b/src/lib/openapi/routes/documents.ts
index 002253923..d31ad375d 100644
--- a/src/lib/openapi/routes/documents.ts
+++ b/src/lib/openapi/routes/documents.ts
@@ -407,7 +407,7 @@ export const inboundDocumentPaths: NonNullable<ZodOpenApiObject["paths"]> = {
           required: false,
           schema: { type: "string", enum: [...DOCUMENT_SOURCE_SYSTEMS] },
           description:
-            "Import source key, first half. Sent here instead of (or agreeing with) the form field, it is checked before the body is read or the hourly allowance is charged.",
+            "Import source key, first half. Sent here (and, if also in the form, agreeing with it), a key the vault already holds is answered at once: the file is not stored or processed and the request does not count toward the hourly upload limit, only toward the lookup allowance shared with `GET /api/documents/inbound/source`.",
         },
         {
           name: "sourceId",
@@ -422,7 +422,7 @@ export const inboundDocumentPaths: NonNullable<ZodOpenApiObject["paths"]> = {
       summary: "Store a document (no extraction)",
       description:
         'STORE-ONLY upload. Stores the raw document ENCRYPTED at rest with `status: STORED` and runs NO extraction — provider-free, no AI consent / budget / egress. A file is always filable, even with no document-scan provider configured. `multipart/form-data`: a `file` plus optional `title`, `kind`, `documentDate` (YYYY-MM-DD), and repeated `episodeIds` form fields (pre-link to the caller\'s illness/condition episodes). Accepted types (magic-byte sniffed, never the wire Content-Type): PDF/JPEG/PNG/WebP/GIF render inline; Office (docx/xlsx/pptx/doc/xls/ppt), text/CSV/Markdown/RTF, TIFF, HEIC/HEIF, XML/JSON are stored verbatim and served download-only. HEIC is stored as-is but attachment-only — prefer transcoding to JPEG client-side for inline preview parity. Error contract: `413` with `meta.reason = "fileTooLarge"` (+ `maxFileBytes`) or `"quotaExceeded"` (+ `quotaBytes`, `usedBytes`); `415` with `meta.reason = "unsupportedType"`. A same-user duplicate (same bytes) returns 200 + `meta.duplicate: true` with the existing row — not an error. `Idempotency-Key` honoured. Read `GET /api/documents/inbound/usage` for the effective limits before offering an upload. AI extraction is a separate opt-in action — see `POST /api/documents/inbound/{id}/extract`.\n\n' +
-        "**Importing from another system (v1.39.2).** Optional `sourceSystem` (`PAPERLESS`, `PAPRA`, `OTHER`) and `sourceId` (its id there, printable, up to 128 characters; needs `sourceSystem`) key the upload. A re-send with a known key is a duplicate: 200 with the live row (`meta.duplicate: true`), or, when the owner DELETED that document, 200 with `data.deleted: true` and `meta.deleted: true` and nothing stored; this holds after the 30-day purge too. The key may instead ride the query string (`?sourceSystem=…&sourceId=…`): it is then answered before the body is read and before the hourly allowance is charged, so a re-send of a document already held costs neither; a key in both places must agree (else 422). A key that is answered with an existing document by its bytes is remembered for that document, so deleting it keeps that key deleted too. `OTHER` is one shared namespace per account: two different systems both sent as `OTHER` must not reuse each other\'s ids. An upload answered as a duplicate or as deleted hands its slot of the hourly allowance back. `aiRead=defer` holds back automatic AI reading for this upload: the thumbnail and a local text index still run, the summary and lab staging do not, and the document stays out of the summary catch-up until the person reads it with AI or generates its summary. Absent, behaviour is unchanged.\n\n" +
+        "**Importing from another system (v1.39.2).** Optional `sourceSystem` (`PAPERLESS`, `PAPRA`, `OTHER`) and `sourceId` (its id there, printable, up to 128 characters; needs `sourceSystem`) key the upload. A re-send with a known key is a duplicate: 200 with the live row (`meta.duplicate: true`), or, when the owner DELETED that document, 200 with `data.deleted: true` and `meta.deleted: true` and nothing stored; this holds after the 30-day purge too. The key may also ride the query string (`?sourceSystem=…&sourceId=…`): a key the vault already holds is then answered at once, the file is not stored or processed, and the request counts only toward the lookup allowance shared with `GET /api/documents/inbound/source` (5000 an hour per token, per person for a session; 429 past it), not toward the hourly upload limit. A key in both places must agree (else 422). Every other upload counts toward the hourly upload limit, duplicates included. A key that is answered with an existing document by its bytes is remembered for that document, so deleting it keeps that key deleted too; one document takes at most 20 such keys, beyond which the upload is refused 409 (`documents.inbound.sourceAliasLimit`). `OTHER` is one shared namespace per account: two different systems both sent as `OTHER` must not reuse each other\'s ids. `aiRead=defer` holds back automatic AI reading for this upload: the thumbnail and a local text index still run, the summary and lab staging do not, and the document stays out of every automatic AI path (the summary catch-up, the automatic index, Index all for search) until the person reads it with AI or generates its summary. Absent, behaviour is unchanged.\n\n" +
         "**Narrow token.** Also reachable with a `documents:write` Bearer (minted at `POST /api/tokens/documents`), which reaches only this route and the source-key lookup `GET /api/documents/inbound/source`. Such a caller draws on a bucket of its own, keyed on the token (default 120 an hour, `DOCUMENT_UPLOAD_LIMIT_PER_HOUR`, clamped 1-1000; the 429 carries `Retry-After` and `X-RateLimit-*`), and gets a `DocumentUploadReceipt` instead of the stored row; its 413 `quotaExceeded` carries no `quotaBytes` / `usedBytes`. The response is an untagged union (row or receipt) on purpose: a discriminator would need a new field on the row every existing client decodes. A cookie or wildcard caller keeps the 60-an-hour per-user bucket and the full row. With the vault module off the answer is 403 `module.disabled` for every caller.",
       requestBody: {
         required: true,
@@ -494,6 +494,11 @@ export const inboundDocumentPaths: NonNullable<ZodOpenApiObject["paths"]> = {
             "Too large: `meta.reason` is `fileTooLarge` (with `maxFileBytes`) or `quotaExceeded` (with `quotaBytes` + `usedBytes`).",
           content: { "application/json": { schema: errorEnvelope } },
         },
+        "409": {
+          description:
+            "The same bytes are already stored under 20 other import source ids (`documents.inbound.sourceAliasLimit`). Nothing was stored or remembered.",
+          content: { "application/json": { schema: errorEnvelope } },
+        },
         "415": {
           description:
             'Unsupported or unidentifiable type (`meta.reason = "unsupportedType"`). Executables, HTML/SVG, and generic archives are always refused.',
@@ -508,7 +513,7 @@ export const inboundDocumentPaths: NonNullable<ZodOpenApiObject["paths"]> = {
       tags: ["Documents"],
       summary: "Look up an import source key",
       description:
-        "Whether the vault already holds a document under this import source key, so an importer can skip a document before downloading it from the source system. Answers exactly what an upload with the same key would: `known`, the document `id` (null once a deleted document was purged), and whether the owner `deleted` it. Checks the document's own key, keys remembered for it when an import sent the same bytes under another key, and the keys of purged documents. Reachable with a `documents:write` Bearer (the scope's second and last route) or a cookie session; stores nothing. 5000 lookups an hour per token (per person for a session); gated on the `inboundDocuments` module.",
+        "Whether the vault already holds a document under this import source key, so an importer can skip a document before downloading it from the source system. Answers exactly what an upload with the same key would: `known`, the document `id` (null once a deleted document was purged), and whether the owner `deleted` it. Checks the document's own key, keys remembered for it when an import sent the same bytes under another key, and the keys of purged documents. Reachable with a `documents:write` Bearer (the scope's second and last route) or a cookie session; stores nothing. 5000 lookups an hour per token (per person for a session), shared with the upload's query-string key check; gated on the `inboundDocuments` module.",
       parameters: [
         {
           name: "sourceSystem",
diff --git a/tests/integration/documents-import.test.ts b/tests/integration/documents-import.test.ts
index cc67863a1..d6b82bcc7 100644
--- a/tests/integration/documents-import.test.ts
+++ b/tests/integration/documents-import.test.ts
@@ -400,7 +400,7 @@ describe("source keys that reach a document by its bytes (#1038)", () => {
   });
 });
 
-describe("re-sends cost no allowance and no body read (#1038)", () => {
+describe("re-sends with the key in the address cost no upload slot (#1038)", () => {
   it("answers a query-string key before the body and the bucket, and the lookup agrees", async () => {
     await seedUser({ inboundDocuments: true });
     token = await mintDocumentToken();
@@ -459,18 +459,25 @@ describe("re-sends cost no allowance and no body read (#1038)", () => {
     expect(blocked.status).toBe(429);
   });
 
-  it("a duplicate by bytes hands its slot back", async () => {
+  it("an upload that sends its body pays its slot, duplicate or not", async () => {
     await seedUser({ inboundDocuments: true });
     token = await mintDocumentToken();
     process.env.DOCUMENT_UPLOAD_LIMIT_PER_HOUR = "2";
     asToken();
     expect((await post(upload(pdf("one")))).status).toBe(201);
-    // Charged and handed back each time; without the refund the second of
-    // these would already meet a spent bucket.
-    expect((await post(upload(pdf("one")))).status).toBe(200);
-    expect((await post(upload(pdf("one")))).status).toBe(200);
-    expect((await post(upload(pdf("two")))).status).toBe(201);
-    expect((await post(upload(pdf("three")))).status).toBe(429);
+    // The same bytes under a new id: answered, remembered, and charged, so
+    // id after id is not a free way to grow the alias table.
+    const again = await post(
+      upload(pdf("one"), { sourceSystem: "OTHER", sourceId: "a1" }),
+    );
+    expect(again.status).toBe(200);
+    expect(
+      (
+        await post(
+          upload(pdf("one"), { sourceSystem: "OTHER", sourceId: "a2" }),
+        )
+      ).status,
+    ).toBe(429);
   });
 });