feat: move Files to its own process; add window server messaging (multi-format clipboard, drag and drop), undo/redo, sidebar, breadcrumbs, thumbnails, file type icons, New menu and proper text fields

kernel/src/Api/DataTransfer.hpp

@@ -0,0 +1,52 @@
+/*
+    * DataTransfer.hpp
+    * Multi-format payloads shared by the clipboard and drag and drop
+    * Copyright (c) 2026 Daniel Hammer
+*/
+
+#pragma once
+#include <cstdint>
+#include "Syscall.hpp"
+
+// A transfer is a small set of formats, each one MIME type plus bytes, all
+// owned by the kernel heap. Producers offer every representation they can
+// (a file list and its paths as text, say) and each consumer reads the one it
+// understands. The clipboard holds one transfer per user; the window server
+// holds the active drag's.
+namespace DataTransfer {
+
+    struct Format {
+        char     mime[montauk::abi::TRANSFER_MIME_MAX];
+        uint8_t* data;
+        uint32_t len;
+    };
+
+    struct Transfer {
+        Format   formats[montauk::abi::TRANSFER_MAX_FORMATS];
+        uint32_t count;
+    };
+
+    // Copy `count` formats in from user memory, validating every pointer the
+    // items carry (the item array itself must already be validated). On
+    // failure `out` is left empty. Returns a StatusCodes value.
+    int BuildFromUser(const montauk::abi::TransferItem* items, uint32_t count, Transfer& out);
+
+    // A transfer holding just `text` as TRANSFER_MIME_TEXT.
+    int BuildText(const char* text, uint32_t len, Transfer& out);
+
+    void Free(Transfer& transfer);
+
+    // Exact match first; a request without parameters ("text/plain") also
+    // matches a stored format that has them ("text/plain;charset=utf-8").
+    const Format* Find(const Transfer& transfer, const char* mime);
+
+    uint32_t ListFormats(const Transfer& transfer, montauk::abi::TransferFormatInfo* out, uint32_t max);
+
+    // Copy a format to a (validated) user buffer. *outLen always receives the
+    // full length; BufferTooSmall when it does not fit, nothing copied then.
+    int CopyOut(const Format& format, void* buffer, uint32_t bufferLen, uint32_t* outLen);
+
+    // MIME string checks shared by every entry point: "type/subtype" with
+    // optional parameters, printable ASCII, shorter than TRANSFER_MIME_MAX.
+    bool ValidMime(const char* mime);
+}