diff --git a/docs/api/openapi.yaml b/docs/api/openapi.yaml
index 756279cdb..291fc5562 100644
--- a/docs/api/openapi.yaml
+++ b/docs/api/openapi.yaml
@@ -26193,6 +26193,15 @@ components:
             - attachment
         hasContentIndex:
           type: boolean
+        contentIndexSource:
+          anyOf:
+            - type: string
+              enum:
+                - vision
+                - text-ocr
+                - local-pdf
+                - local-ocr
+            - type: "null"
         createdAt:
           type: string
         updatedAt:
@@ -26214,6 +26223,7 @@ components:
         - conditionLinks
         - servingClass
         - hasContentIndex
+        - contentIndexSource
         - createdAt
         - updatedAt
       additionalProperties: false
@@ -26222,8 +26232,10 @@ components:
         (plaintext); `documentDate` is the user filing date; `reportDate` is the model-transcribed date (null until
         extraction runs). `servingClass` says how `/original` delivers the file — render inline (`inline`) or
         download-only (`attachment`); render/download by it, never by MIME guess. `hasContentIndex` is true when the
-        document has a content-search index (drives the re-index affordance). Treat an unknown `kind` value as OTHER
-        when decoding.
+        document has a content-search index (auto-indexed on upload); `contentIndexSource` says how that index was
+        produced — `vision` means an AI provider read the original, the other values are provider-free local
+        extractions, and it is null when `hasContentIndex` is false. Treat an unknown `kind` value as OTHER when
+        decoding.
     DocumentConditionLink:
       type: object
       properties:
@@ -26448,6 +26460,15 @@ components:
             - attachment
         hasContentIndex:
           type: boolean
+        contentIndexSource:
+          anyOf:
+            - type: string
+              enum:
+                - vision
+                - text-ocr
+                - local-pdf
+                - local-ocr
+            - type: "null"
         createdAt:
           type: string
         updatedAt:
@@ -26473,6 +26494,7 @@ components:
         - conditionLinks
         - servingClass
         - hasContentIndex
+        - contentIndexSource
         - createdAt
         - updatedAt
         - facts
diff --git a/src/app/api/documents/inbound/[id]/route.ts b/src/app/api/documents/inbound/[id]/route.ts
index b7b76581d..2edea326d 100644
--- a/src/app/api/documents/inbound/[id]/route.ts
+++ b/src/app/api/documents/inbound/[id]/route.ts
@@ -27,7 +27,10 @@ import { serialiseDocumentDetail } from "@/lib/documents/store";
 import { annotate } from "@/lib/logging/context";
 import { requireModuleEnabled } from "@/lib/modules/gate";
 import { checkRateLimit, rateLimitHeaders } from "@/lib/rate-limit";
-import { documentUpdateSchema } from "@/lib/validations/inbound-documents";
+import {
+  documentUpdateSchema,
+  toContentIndexSource,
+} from "@/lib/validations/inbound-documents";
 import type { Prisma } from "@/generated/prisma/client";
 
 type RouteParams = { params: Promise<{ id: string }> };
@@ -80,7 +83,7 @@ export const GET = apiHandler(
       loadConditionLinks(user.id, [document.id]),
       prisma.documentContentIndex.findUnique({
         where: { documentId: document.id },
-        select: { id: true },
+        select: { source: true },
       }),
     ]);
 
@@ -95,6 +98,7 @@ export const GET = apiHandler(
         document.facts,
         links.get(document.id) ?? [],
         contentIndex !== null,
+        toContentIndexSource(contentIndex?.source),
       ),
     );
   },
@@ -173,7 +177,13 @@ export const PATCH = apiHandler(
       omit: { contentEncrypted: true },
       include: { facts: { orderBy: { createdAt: "asc" } } },
     });
-    const links = await loadConditionLinks(user.id, [document.id]);
+    const [links, contentIndex] = await Promise.all([
+      loadConditionLinks(user.id, [document.id]),
+      prisma.documentContentIndex.findUnique({
+        where: { documentId: document.id },
+        select: { source: true },
+      }),
+    ]);
 
     const touched = [
       ...Object.keys(data),
@@ -199,6 +209,8 @@ export const PATCH = apiHandler(
         document,
         document.facts,
         links.get(document.id) ?? [],
+        contentIndex !== null,
+        toContentIndexSource(contentIndex?.source),
       ),
     );
   },
diff --git a/src/app/api/documents/inbound/route.ts b/src/app/api/documents/inbound/route.ts
index bf25857da..e3985b0f7 100644
--- a/src/app/api/documents/inbound/route.ts
+++ b/src/app/api/documents/inbound/route.ts
@@ -55,6 +55,7 @@ import { checkRateLimit, rateLimitHeaders } from "@/lib/rate-limit";
 import {
   documentCreateSchema,
   documentListQuerySchema,
+  toContentIndexSource,
 } from "@/lib/validations/inbound-documents";
 import type { Prisma } from "@/generated/prisma/client";
 
@@ -506,15 +507,16 @@ export const GET = apiHandler(async (request: Request) => {
     page.map((d) => d.id),
   );
 
-  // Which of the page's documents have a content index (drives `hasContentIndex`
-  // + the re-index affordance). One indexed grouped query; never the ciphertext.
-  const indexedIds = new Set<string>();
+  // Which of the page's documents have a content index (drives the searchable
+  // status + the provenance the UI reads to tell an AI-read document from a
+  // locally-indexed one). One grouped query; never the ciphertext.
+  const indexSources = new Map<string, string>();
   if (page.length > 0) {
     const indexed = await prisma.documentContentIndex.findMany({
       where: { userId: user.id, documentId: { in: page.map((d) => d.id) } },
-      select: { documentId: true },
+      select: { documentId: true, source: true },
     });
-    for (const row of indexed) indexedIds.add(row.documentId);
+    for (const row of indexed) indexSources.set(row.documentId, row.source);
   }
 
   annotate({
@@ -533,7 +535,8 @@ export const GET = apiHandler(async (request: Request) => {
         doc,
         factCounts.get(doc.id) ?? { factCount: 0, pendingCount: 0 },
         linkMap.get(doc.id) ?? [],
-        indexedIds.has(doc.id),
+        indexSources.has(doc.id),
+        toContentIndexSource(indexSources.get(doc.id)),
       ),
     ),
     nextCursor,
diff --git a/src/components/documents/__tests__/document-card.test.tsx b/src/components/documents/__tests__/document-card.test.tsx
index 9e58adefa..61680c65e 100644
--- a/src/components/documents/__tests__/document-card.test.tsx
+++ b/src/components/documents/__tests__/document-card.test.tsx
@@ -32,6 +32,7 @@ function doc(overrides: Partial<InboundDocumentDto> = {}): InboundDocumentDto {
     conditionLinks: [{ episodeId: "ep-knee", name: "Knie" }],
     servingClass: "inline",
     hasContentIndex: false,
+    contentIndexSource: null,
     createdAt: "2025-10-05T08:00:00.000Z",
     updatedAt: "2025-10-05T08:00:00.000Z",
     ...overrides,
diff --git a/src/components/documents/__tests__/episode-documents-card.test.tsx b/src/components/documents/__tests__/episode-documents-card.test.tsx
index 6e352ff82..9d838e54f 100644
--- a/src/components/documents/__tests__/episode-documents-card.test.tsx
+++ b/src/components/documents/__tests__/episode-documents-card.test.tsx
@@ -52,6 +52,7 @@ function doc(id: string, title: string): InboundDocumentDto {
     conditionLinks: [{ episodeId: "ep1", name: "Knee" }],
     servingClass: "inline",
     hasContentIndex: false,
+    contentIndexSource: null,
     createdAt: "2025-10-05T08:00:00.000Z",
     updatedAt: "2025-10-05T08:00:00.000Z",
   };
diff --git a/src/components/documents/__tests__/vault-utils.test.ts b/src/components/documents/__tests__/vault-utils.test.ts
index 2e9c79ca8..8af11a9c7 100644
--- a/src/components/documents/__tests__/vault-utils.test.ts
+++ b/src/components/documents/__tests__/vault-utils.test.ts
@@ -33,6 +33,7 @@ function doc(overrides: Partial<InboundDocumentDto> = {}): InboundDocumentDto {
     conditionLinks: [],
     servingClass: "inline",
     hasContentIndex: false,
+    contentIndexSource: null,
     createdAt: "2026-03-11T08:00:00.000Z",
     updatedAt: "2026-03-11T08:00:00.000Z",
     ...overrides,
diff --git a/src/lib/documents/store.ts b/src/lib/documents/store.ts
index c18f2fa70..7e6d38a00 100644
--- a/src/lib/documents/store.ts
+++ b/src/lib/documents/store.ts
@@ -19,6 +19,7 @@ import type {
 import { servingClassFor } from "@/lib/documents/upload-policy";
 import type {
   DocumentConditionLinkDto,
+  DocumentContentIndexSourceValue,
   ExtractedFactDto,
   FactData,
   FactProvenance,
@@ -135,6 +136,7 @@ export function serialiseDocument(
   counts: { factCount: number; pendingCount: number },
   conditionLinks: DocumentConditionLinkDto[] = [],
   hasContentIndex = false,
+  contentIndexSource: DocumentContentIndexSourceValue | null = null,
 ): InboundDocumentDto {
   return {
     id: doc.id,
@@ -157,6 +159,7 @@ export function serialiseDocument(
     conditionLinks,
     servingClass: servingClassFor(doc.mimeType),
     hasContentIndex,
+    contentIndexSource: hasContentIndex ? contentIndexSource : null,
     createdAt: doc.createdAt.toISOString(),
     updatedAt: doc.updatedAt.toISOString(),
   };
@@ -183,6 +186,7 @@ export function serialiseDocumentDetail(
   facts: ExtractedFact[],
   conditionLinks: DocumentConditionLinkDto[] = [],
   hasContentIndex = false,
+  contentIndexSource: DocumentContentIndexSourceValue | null = null,
 ): InboundDocumentDetailDto {
   const pendingCount = facts.filter((f) => f.status === "PENDING").length;
   // `factCount` excludes REJECTED facts (a rejected fact is discarded, not part
@@ -194,6 +198,7 @@ export function serialiseDocumentDetail(
       { factCount, pendingCount },
       conditionLinks,
       hasContentIndex,
+      contentIndexSource,
     ),
     facts: facts.map(serialiseFact),
   };
diff --git a/src/lib/openapi/routes/documents.ts b/src/lib/openapi/routes/documents.ts
index 565ed7265..f43b917cb 100644
--- a/src/lib/openapi/routes/documents.ts
+++ b/src/lib/openapi/routes/documents.ts
@@ -108,13 +108,16 @@ const inboundDocument = z
     conditionLinks: z.array(conditionLink),
     servingClass: z.enum(["inline", "attachment"]),
     hasContentIndex: z.boolean(),
+    contentIndexSource: z
+      .enum(["vision", "text-ocr", "local-pdf", "local-ocr"])
+      .nullable(),
     createdAt: z.string(),
     updatedAt: z.string(),
   })
   .meta({
     id: "InboundDocument",
     description:
-      "A stored document. The raw bytes are stored encrypted at rest and never returned; this is the metadata + staging summary. `status` is STORED for a freshly uploaded file (no extraction run). `title` is the user label (plaintext); `documentDate` is the user filing date; `reportDate` is the model-transcribed date (null until extraction runs). `servingClass` says how `/original` delivers the file — render inline (`inline`) or download-only (`attachment`); render/download by it, never by MIME guess. `hasContentIndex` is true when the document has a content-search index (drives the re-index affordance). Treat an unknown `kind` value as OTHER when decoding.",
+      "A stored document. The raw bytes are stored encrypted at rest and never returned; this is the metadata + staging summary. `status` is STORED for a freshly uploaded file (no extraction run). `title` is the user label (plaintext); `documentDate` is the user filing date; `reportDate` is the model-transcribed date (null until extraction runs). `servingClass` says how `/original` delivers the file — render inline (`inline`) or download-only (`attachment`); render/download by it, never by MIME guess. `hasContentIndex` is true when the document has a content-search index (auto-indexed on upload); `contentIndexSource` says how that index was produced — `vision` means an AI provider read the original, the other values are provider-free local extractions, and it is null when `hasContentIndex` is false. Treat an unknown `kind` value as OTHER when decoding.",
   });
 
 const inboundDocumentDetail = inboundDocument
diff --git a/src/lib/validations/inbound-documents.ts b/src/lib/validations/inbound-documents.ts
index 7b86b2c50..5a6cf8834 100644
--- a/src/lib/validations/inbound-documents.ts
+++ b/src/lib/validations/inbound-documents.ts
@@ -59,6 +59,45 @@ export const INBOUND_DOCUMENT_KINDS = [
 ] as const;
 export type InboundDocumentKindValue = (typeof INBOUND_DOCUMENT_KINDS)[number];
 
+/**
+ * How a document's content index was produced (mirrors the server `source`
+ * column). `vision` means an AI provider read the original (the AI-first path);
+ * every other value is a provider-free local extraction. The UI reads it to
+ * tell an AI-read document from a locally-indexed one — the former already had
+ * the richer read, the latter can still be offered "Read with AI".
+ */
+export const DOCUMENT_CONTENT_INDEX_SOURCES = [
+  "vision",
+  "text-ocr",
+  "local-pdf",
+  "local-ocr",
+] as const;
+export type DocumentContentIndexSourceValue =
+  (typeof DOCUMENT_CONTENT_INDEX_SOURCES)[number];
+
+/** True when the index was produced by an AI provider reading the original. */
+export function isAiReadSource(
+  source: DocumentContentIndexSourceValue | string | null,
+): boolean {
+  return source === "vision";
+}
+
+/**
+ * Narrow the free-String DB `source` column to the DTO union, or `null` for an
+ * absent / unrecognised value. The column is a free String server-side (adding
+ * a source needs no migration) so the read path guards it before it hits the
+ * contract.
+ */
+export function toContentIndexSource(
+  source: string | null | undefined,
+): DocumentContentIndexSourceValue | null {
+  return DOCUMENT_CONTENT_INDEX_SOURCES.includes(
+    source as DocumentContentIndexSourceValue,
+  )
+    ? (source as DocumentContentIndexSourceValue)
+    : null;
+}
+
 /** The document lifecycle states. STORED is the library default. */
 export const INBOUND_DOCUMENT_STATUSES = [
   "STORED",
@@ -230,10 +269,17 @@ export interface InboundDocumentDto {
   servingClass: "inline" | "attachment";
   /**
    * Whether the document has a content-search index (encrypted extracted text +
-   * blind token array). Drives the "index for search" / re-index affordances;
-   * `false` until the document is indexed.
+   * blind token array). `false` until the document is indexed (auto-indexed on
+   * upload; the UI reads this for the searchable status, not as a to-do).
    */
   hasContentIndex: boolean;
+  /**
+   * How that index was produced — `vision` (an AI provider read the original)
+   * vs a local extraction (`local-pdf` / `text-ocr` / `local-ocr`), or `null`
+   * when `hasContentIndex` is false. Lets the UI tell an AI-read document from
+   * a locally-indexed one and offer a richer "Read with AI" pass on the latter.
+   */
+  contentIndexSource: DocumentContentIndexSourceValue | null;
   createdAt: string;
   updatedAt: string;
 }