diff --git a/apps/readest.koplugin/library/syncbooks.lua b/apps/readest.koplugin/library/syncbooks.lua
index 0e93e258..3c01d2d4 100644
--- a/apps/readest.koplugin/library/syncbooks.lua
+++ b/apps/readest.koplugin/library/syncbooks.lua
@@ -673,6 +673,27 @@ function M.downloadCover(book, opts, cb)
     end)
 end
 
+-- ---------------------------------------------------------------------------
+-- extractLocalCover(file_path, dst_png) → true on success
+-- ---------------------------------------------------------------------------
+-- Render the book's embedded cover to dst_png as PNG via coverbrowser's
+-- BookInfo:getCoverImage, which opens the document, honors any custom cover
+-- the user set in KOReader, and returns a native-resolution blitbuffer.
+-- Passing a nil document + the file path makes BookInfo open + close the
+-- document itself (same call form calibre.koplugin uses). Live-KOReader only
+-- (FileManagerBookInfo + blitbuffer); the success/failure wiring is exercised
+-- by a busted test that injects a fake BookInfo.
+function M.extractLocalCover(file_path, dst_png)
+    if not file_path or not dst_png then return false end
+    local ok, FileManagerBookInfo = pcall(require, "apps/filemanager/filemanagerbookinfo")
+    if not ok or not FileManagerBookInfo then return false end
+    local got, cover_bb = pcall(FileManagerBookInfo.getCoverImage, FileManagerBookInfo, nil, file_path)
+    if not got or not cover_bb then return false end
+    local wrote = cover_bb:writeToFile(dst_png, "png")
+    if cover_bb.free then cover_bb:free() end
+    return wrote == true
+end
+
 -- ---------------------------------------------------------------------------
 -- uploadBook(book, opts, cb) — push a local book file to Readest cloud.
 -- ---------------------------------------------------------------------------
@@ -684,10 +705,12 @@ end
 --      downloadBook for the same UX trade-off — UI freezes during the
 --      upload but the dialog stays visible).
 --
--- Cover.png handling is intentionally minimal in v1: if a cover is
--- already cached at <covers_dir>/<hash>.png (from a prior cloud
--- download), upload it too. Books without a cached cover skip the cover
--- step silently — the server tolerates books with no cover row.
+-- Cover.png handling: if a cover is already cached at <covers_dir>/<hash>.png
+-- (from a prior cloud download) upload it as-is; otherwise extract the
+-- embedded cover from the local file via extractLocalCover so books that
+-- originated on this device still get a cover in the cloud (issue #4374).
+-- Best-effort: books with no extractable cover skip the cover step silently
+-- and the server tolerates a book with no cover row.
 --
 -- opts: { sync_auth, sync_path, settings, covers_dir = optional }
 -- book: row with { hash, format, file_path, title, source_title }
@@ -723,6 +746,20 @@ function M.uploadBook(book, opts, cb)
     local cover_attr = cover_path and lfs.attributes(cover_path) or nil
     local has_cover = cover_attr and cover_attr.mode == "file"
 
+    -- No cached cloud cover (e.g. a book that originated on this device and
+    -- was never downloaded from the cloud): extract the embedded cover from
+    -- the local file so it still ships a cover.png. Cached under covers_dir so
+    -- the Library view reuses it just like a downloaded cover would.
+    if not has_cover and cover_path then
+        if not lfs.attributes(opts.covers_dir, "mode") then
+            lfs.mkdir(opts.covers_dir)
+        end
+        if M.extractLocalCover(book.file_path, cover_path) then
+            cover_attr = lfs.attributes(cover_path)
+            has_cover = cover_attr and cover_attr.mode == "file"
+        end
+    end
+
     -- Synchronous PUT helper. Returns (ok, code, body_or_err) — body
     -- captures the S3/R2 XML error response on failure, so the caller
     -- can log something more useful than just "table: 0x...". Bug
diff --git a/apps/readest.koplugin/spec/library/syncbooks_spec.lua b/apps/readest.koplugin/spec/library/syncbooks_spec.lua
index dccf2885..b4139b08 100644
--- a/apps/readest.koplugin/spec/library/syncbooks_spec.lua
+++ b/apps/readest.koplugin/spec/library/syncbooks_spec.lua
@@ -251,6 +251,81 @@ describe("library.syncbooks", function()
         end)
     end)
 
+    -- =====================================================================
+    -- extractLocalCover(file_path, dst_png) — render a book's embedded cover
+    -- to dst_png as PNG via coverbrowser's BookInfo:getCoverImage so
+    -- uploadBook can ship a cover for books that originated on this device
+    -- (issue #4374), not just ones previously downloaded from the cloud.
+    -- The blitbuffer/document work is live-KOReader-only, so we inject a fake
+    -- BookInfo via package.loaded and assert the success/failure wiring.
+    -- =====================================================================
+    describe("extractLocalCover", function()
+        local BI_KEY = "apps/filemanager/filemanagerbookinfo"
+        local saved_bookinfo
+
+        before_each(function()
+            saved_bookinfo = package.loaded[BI_KEY]
+        end)
+        after_each(function()
+            package.loaded[BI_KEY] = saved_bookinfo
+        end)
+
+        it("writes the cover as PNG and returns true when the book has a cover", function()
+            local wrote, freed
+            local fake_bb = {
+                writeToFile = function(_self, path, fmt)
+                    wrote = { path = path, fmt = fmt }
+                    return true
+                end,
+                free = function() freed = true end,
+            }
+            package.loaded[BI_KEY] = {
+                getCoverImage = function(_self, document, file)
+                    -- Called with a nil document + the book's path so BookInfo
+                    -- opens the file itself (matches calibre.koplugin's usage).
+                    assert.is_nil(document)
+                    assert.are.equal("/books/foo.epub", file)
+                    return fake_bb
+                end,
+            }
+
+            local ok = syncbooks.extractLocalCover("/books/foo.epub", "/cache/abc.png")
+
+            assert.is_true(ok)
+            assert.are.equal("/cache/abc.png", wrote.path)
+            assert.are.equal("png", wrote.fmt)
+            assert.is_true(freed, "the cover blitbuffer must be freed")
+        end)
+
+        it("returns false when the book has no extractable cover", function()
+            package.loaded[BI_KEY] = {
+                getCoverImage = function() return nil end,
+            }
+            assert.is_false(syncbooks.extractLocalCover("/books/foo.epub", "/cache/abc.png"))
+        end)
+
+        it("returns false when the PNG write fails", function()
+            package.loaded[BI_KEY] = {
+                getCoverImage = function()
+                    return { writeToFile = function() return false end, free = function() end }
+                end,
+            }
+            assert.is_false(syncbooks.extractLocalCover("/books/foo.epub", "/cache/abc.png"))
+        end)
+
+        it("returns false when coverbrowser's BookInfo isn't available", function()
+            -- Neither package.loaded nor package.path resolves the module in
+            -- the test env, so require() errors and the pcall guard kicks in.
+            package.loaded[BI_KEY] = nil
+            assert.is_false(syncbooks.extractLocalCover("/books/foo.epub", "/cache/abc.png"))
+        end)
+
+        it("returns false for missing arguments", function()
+            assert.is_false(syncbooks.extractLocalCover(nil, "/cache/abc.png"))
+            assert.is_false(syncbooks.extractLocalCover("/books/foo.epub", nil))
+        end)
+    end)
+
     -- =====================================================================
     -- syncBooks(opts, mode, cb, before_push) — bidirectional orchestration.
     --