diff --git a/buyer/.env.example b/buyer/.env.example
index 8c30755..eb7de34 100644
--- a/buyer/.env.example
+++ b/buyer/.env.example
@@ -42,6 +42,8 @@ NETWORK_ID=0
 # Upload a PDF → chunk it → pay suppliers to summarize each chunk (one escrow
 # per map + reduce call) → full-book summary. All knobs are optional; defaults
 # shown. Tune the caps to bound spend/abuse on mainnet.
+# Kill switch: "0" disables the feature entirely (every /v1/pdf-* route 503s):
+# PDF_ENABLED=1
 #
 # Hard caps (a job is refused if it would exceed these):
 # PDF_MAX_PAGES=400               # reject books larger than this
diff --git a/buyer/src/config.ts b/buyer/src/config.ts
index 44358b4..9c512ff 100644
--- a/buyer/src/config.ts
+++ b/buyer/src/config.ts
@@ -42,6 +42,10 @@
  *                         API key" page knows where to POST /signup. When
  *                         unset, the SPA falls back to deriving "api." +
  *                         current host.
+ *   PDF_ENABLED         — "1" (default) serves the PDF book summarizer
+ *                         (/v1/pdf-* routes). Set "0" to disable the feature
+ *                         entirely: no PDF job store is opened and every
+ *                         /v1/pdf-* route responds 503.
  */
 
 const HEX64_RE = /^[0-9a-fA-F]{64}$/;
@@ -62,6 +66,7 @@ export interface BuyerConfig {
   password: string;
   sessionSecret: string;
   cookieSecure: boolean;
+  pdfEnabled: boolean;
   gatewayPublicUrl: string;
 }
 
@@ -148,6 +153,18 @@ export function loadConfig(env: Record<string, string | undefined>): BuyerConfig
     cookieSecure = cookieSecureStr === "1";
   }
 
+  // PDF_ENABLED: defaults to true. Set "0" to disable the PDF book summarizer
+  // entirely — runMain skips the JobStore wiring and every /v1/pdf-* route
+  // responds 503. Accept only "0" / "1" to keep boot-time misconfig loud.
+  let pdfEnabled = true;
+  const pdfEnabledStr = env.PDF_ENABLED;
+  if (pdfEnabledStr !== undefined && pdfEnabledStr !== "") {
+    if (pdfEnabledStr !== "0" && pdfEnabledStr !== "1") {
+      throw new Error('loadConfig: PDF_ENABLED must be "0" or "1"');
+    }
+    pdfEnabled = pdfEnabledStr === "1";
+  }
+
   // GATEWAY_PUBLIC_URL — optional. Public base URL of the gateway, surfaced to
   // the SPA via the boot block (no trailing slash). Empty string means the SPA
   // derives the URL from its own host ("api." + location.host).
@@ -167,6 +184,7 @@ export function loadConfig(env: Record<string, string | undefined>): BuyerConfig
     password,
     sessionSecret,
     cookieSecure,
+    pdfEnabled,
     gatewayPublicUrl,
   };
 }
diff --git a/buyer/src/index.ts b/buyer/src/index.ts
index f95c014..4e0be24 100644
--- a/buyer/src/index.ts
+++ b/buyer/src/index.ts
@@ -96,29 +96,36 @@ export async function runMain(env: Record<string, string | undefined>): Promise<
 
   // PDF book summarizer: one job registry, sharing the live marketplace SDK,
   // chain, wallet, and (optional) archive. Caps come from PDF_* env vars.
+  // PDF_ENABLED=0 skips the whole wiring; createApp then registers every
+  // /v1/pdf-* route as a 503 stub (feature disabled).
   const pdfCaps = loadPdfCaps(env);
-  // Durable job store (SQLite under ARCHIVE_DIR) so past summaries survive
-  // restarts and navigation. Best-effort: if it can't open, jobs fall back to
-  // in-memory only (lost on restart) but the feature still works.
-  let pdfJobDb: PdfJobDb | undefined;
-  try {
-    pdfJobDb = new PdfJobDb(config.archiveDir);
-    console.log(`[buyer] pdf job store at ${config.archiveDir}/pdf-jobs.db`);
-  } catch (err) {
-    console.error(
-      `[buyer] failed to open pdf job store at ${config.archiveDir}:`,
-      err instanceof Error ? err.message : String(err),
-    );
+  let jobStore: JobStore | undefined;
+  if (config.pdfEnabled) {
+    // Durable job store (SQLite under ARCHIVE_DIR) so past summaries survive
+    // restarts and navigation. Best-effort: if it can't open, jobs fall back to
+    // in-memory only (lost on restart) but the feature still works.
+    let pdfJobDb: PdfJobDb | undefined;
+    try {
+      pdfJobDb = new PdfJobDb(config.archiveDir);
+      console.log(`[buyer] pdf job store at ${config.archiveDir}/pdf-jobs.db`);
+    } catch (err) {
+      console.error(
+        `[buyer] failed to open pdf job store at ${config.archiveDir}:`,
+        err instanceof Error ? err.message : String(err),
+      );
+    }
+    jobStore = new JobStore({
+      marketplace,
+      chain,
+      walletKey,
+      indexerUrl: config.indexerUrl,
+      archive,
+      caps: pdfCaps,
+      db: pdfJobDb,
+    });
+  } else {
+    console.log("[buyer] pdf summarizer disabled (PDF_ENABLED=0)");
   }
-  const jobStore = new JobStore({
-    marketplace,
-    chain,
-    walletKey,
-    indexerUrl: config.indexerUrl,
-    archive,
-    caps: pdfCaps,
-    db: pdfJobDb,
-  });
 
   const app = createApp({
     distPath,
diff --git a/buyer/src/pdf/routes.ts b/buyer/src/pdf/routes.ts
index a89bed9..be9f0c3 100644
--- a/buyer/src/pdf/routes.ts
+++ b/buyer/src/pdf/routes.ts
@@ -40,7 +40,7 @@ export function registerPdfRoutes(
         res,
         503,
         "service_unavailable",
-        "PDF summarizer disabled (buyer booted without chain/marketplace/archive deps)",
+        "PDF summarizer disabled",
       );
     app.post("/v1/pdf-upload", disabled);
     app.all(/^\/v1\/pdf-jobs(\/.*)?$/, disabled);
diff --git a/tests/unit/buyer-server-config.test.ts b/tests/unit/buyer-server-config.test.ts
index a706785..040005a 100644
--- a/tests/unit/buyer-server-config.test.ts
+++ b/tests/unit/buyer-server-config.test.ts
@@ -87,6 +87,19 @@ describe("loadConfig(env)", () => {
     const env = { ...VALID_ENV, COOKIE_SECURE: "true" };
     expect(() => loadConfig(env)).toThrow(/COOKIE_SECURE/);
   });
+
+  it("defaults pdfEnabled to true when PDF_ENABLED is not provided", () => {
+    expect(loadConfig(VALID_ENV).pdfEnabled).toBe(true);
+  });
+
+  it('honours PDF_ENABLED="0" (summarizer kill switch)', () => {
+    const config = loadConfig({ ...VALID_ENV, PDF_ENABLED: "0" });
+    expect(config.pdfEnabled).toBe(false);
+  });
+
+  it("throws when PDF_ENABLED is not 0 or 1", () => {
+    expect(() => loadConfig({ ...VALID_ENV, PDF_ENABLED: "false" })).toThrow(/PDF_ENABLED/);
+  });
 });
 
 // ─── createApp tests ──────────────────────────────────────────────────────────