diff --git a/packages/blocks-cli/scripts/fast-deploy-kv.test.ts b/packages/blocks-cli/scripts/fast-deploy-kv.test.ts
index c8659074..910bfeb9 100644
--- a/packages/blocks-cli/scripts/fast-deploy-kv.test.ts
+++ b/packages/blocks-cli/scripts/fast-deploy-kv.test.ts
@@ -10,6 +10,7 @@ import {
   snapshotKey,
 } from "@decocms/blocks/cms";
 import { createKvRestClient, type KvRestClient, kvConfigFromEnv } from "./lib/cf-kv-rest";
+import { readDecofileFromDir } from "./lib/read-decofile";
 import { kvNamespaceIdFromToml, kvNamespaceIdFromWrangler } from "./lib/wrangler-config";
 import {
   buildSnapshot,
@@ -341,3 +342,71 @@ describe("sync-helpers", () => {
     expect(paths).not.toContain(undefined);
   });
 });
+
+describe("readDecofileFromDir — CSV redirects", () => {
+  /** A site tree: `.deco/blocks/*.json` + `public/*.csv`. Returns the blocks dir. */
+  function makeSite(blocks: Record<string, unknown>, csv: Record<string, string>): string {
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), "decofile-csv-"));
+    const blocksDir = path.join(root, ".deco", "blocks");
+    fs.mkdirSync(blocksDir, { recursive: true });
+    fs.mkdirSync(path.join(root, "public"), { recursive: true });
+    for (const [name, value] of Object.entries(blocks)) {
+      fs.writeFileSync(path.join(blocksDir, name), JSON.stringify(value));
+    }
+    for (const [name, value] of Object.entries(csv)) {
+      fs.writeFileSync(path.join(root, "public", name), value);
+    }
+    return blocksDir;
+  }
+
+  it("materializes a CSV loader nested under site.routes[] into a top-level block", () => {
+    // The shape that broke production: the CSV loader is nested inside
+    // `site.json -> routes[]`, where `loadRedirects` (top-level only) can't see
+    // it, and the CSV itself was only ever read by the unported Fresh loader.
+    const blocksDir = makeSite(
+      {
+        "site.json": {
+          __resolveType: "site/apps/site.ts",
+          routes: [{ __resolveType: "website/loaders/redirectsFromCsv.ts", from: "static/r.csv" }],
+        },
+      },
+      { "r.csv": "from,to,type\n/old,/new,permanent\n/tmp,/other\n" },
+    );
+
+    const { blocks } = readDecofileFromDir(blocksDir, { silent: true });
+
+    expect(blocks["__csv_redirects__r.csv"]).toEqual({
+      __resolveType: "website/loaders/redirects.ts",
+      redirects: [
+        { from: "/old", to: "/new", type: "permanent" },
+        { from: "/tmp", to: "/other", type: "temporary" },
+      ],
+    });
+    // The real blocks are untouched.
+    expect(blocks.site).toBeDefined();
+  });
+
+  it("lets a real block win over the synthetic one on a key collision", () => {
+    const blocksDir = makeSite(
+      {
+        "site.json": {
+          routes: [{ __resolveType: "website/loaders/redirectsFromCsv.ts", from: "r.csv" }],
+        },
+        // Decodes to exactly the synthetic key the CSV materializer produces.
+        "__csv_redirects__r.csv.json": { curated: true },
+      },
+      { "r.csv": "/old,/new\n" },
+    );
+
+    const { blocks } = readDecofileFromDir(blocksDir, { silent: true });
+
+    // `{ ...csv, ...blocks }` — the curated block wins, never the synthetic one.
+    expect(blocks["__csv_redirects__r.csv"]).toEqual({ curated: true });
+  });
+
+  it("is a no-op when no CSV loader is referenced", () => {
+    const blocksDir = makeSite({ "site.json": { __resolveType: "site/apps/site.ts" } }, {});
+    const { blocks } = readDecofileFromDir(blocksDir, { silent: true });
+    expect(Object.keys(blocks)).toEqual(["site"]);
+  });
+});
diff --git a/packages/blocks-cli/scripts/lib/read-decofile.ts b/packages/blocks-cli/scripts/lib/read-decofile.ts
index fab18a40..5aca0fce 100644
--- a/packages/blocks-cli/scripts/lib/read-decofile.ts
+++ b/packages/blocks-cli/scripts/lib/read-decofile.ts
@@ -6,7 +6,7 @@
  * the fast-deploy CI scripts (`migrate-blocks-to-kv.ts`, `sync-blocks-to-kv.ts`)
  * produce a decofile byte-identical to the bundled `blocks.gen` snapshot.
  *
- * Reuses `scripts/lib/blocks-dedupe.ts`.
+ * Reuses `scripts/lib/blocks-dedupe.ts` and `scripts/lib/csv-redirects.ts`.
  */
 
 import * as fs from "node:fs";
@@ -18,6 +18,7 @@ import {
   decodeBlockNameWithPasses,
   mergeCandidates,
 } from "./blocks-dedupe";
+import { buildCsvRedirectBlocks } from "./csv-redirects";
 
 export interface ReadDecofileResult {
   /** Decoded block key → parsed block JSON. */
@@ -66,5 +67,15 @@ export function readDecofileFromDir(blocksDir: string, opts: { silent?: boolean
   for (const [key, candidate] of Object.entries(winners)) {
     blocks[key] = candidate.parsed;
   }
-  return { blocks, collisions };
+
+  // Synthetic `__csv_redirects__*` blocks, exactly as `generate-blocks` builds
+  // them. Without this the KV snapshot is NOT byte-identical to `blocks.gen`:
+  // a site whose redirects come from a CSV would lose every one of them the
+  // moment the bundled snapshot stops being the fallback (the fastDeploy stub
+  // makes KV the only source), turning migration 301s into silent 404s.
+  // Same precedence as the generator — a curated CMS redirect wins over CSV.
+  const csvBlocks = buildCsvRedirectBlocks(blocks, { blocksDir, silent: opts.silent });
+  const merged = Object.keys(csvBlocks).length ? { ...csvBlocks, ...blocks } : blocks;
+
+  return { blocks: merged, collisions };
 }