feat: add bounded file byte reads

docs/DEV_PLUGINS.md

@@ -85,12 +85,13 @@ Frontend bundles are mounted with a plugin-scoped API created by
 - `capabilities.list/get/has`
 - `commands.register/execute` for handlers declared in `contributes.commands`
 - `events.publish/subscribe` using the bundled frontend event bus
-- `files.list/metadata/readText/writeText/createFolder/move/trash/openExternal/showInFolder`
+- `files.list/metadata/readText/readBytes/writeText/createFolder/move/trash/openExternal/showInFolder`
   for canonical vault-relative slash paths guarded by `files.read`,
   `files.write`, `files.delete`, and `files.openExternal`. Backslashes,
   Windows absolute paths, UNC paths, traversal, `.verstak` variants, and
   symlink read/write/move/trash/external-open operations are rejected. Text
-  read/write is UTF-8 only and limited to 2 MB for reads.
+  read/write is UTF-8 only and limited to 2 MB for text reads; `readBytes`
+  returns base64 for regular files up to 8 MB.
 - `workbench.openResource/editResource` for routing vault resources to
   contributed `openProviders`. Plugins must declare `workbench.open`; this is a
   policy/contract check. Files and Notes plugins call this API and do not import

docs/PLUGIN_RUNTIME.md

@@ -437,6 +437,8 @@ contributions summary.
 - `files.list(relativeDir)` — list directory using a vault-relative path.
 - `files.metadata(relativePath)` — returns file/folder/symlink metadata.
 - `files.readText(relativePath)` — reads a UTF-8 regular file, with a size limit.
+- `files.readBytes(relativePath)` — reads a regular file up to 8 MB and returns
+  `{ relativePath, size, mimeHint, dataBase64 }` for bounded binary preview use.
 - `files.writeText(relativePath, content, options)` — atomically writes text via
   temp-file-and-rename. `options.createIfMissing` and `options.overwrite`
   control conflicts.
@@ -464,8 +466,9 @@ contributions summary.
 - `files.metadata` may report a final symlink as `type: "symlink"`, but
   `files.list` through a symlink directory and all read/write/move/trash
   operations through symlinks are forbidden in Milestone 6a.
-- Files API is text-only for read/write in Milestone 6a. `readText` is limited
-  to UTF-8 regular files up to 2 MB. Binary streaming is deferred.
+- Files API writes are text-only. `readText` is limited to UTF-8 regular files
+  up to 2 MB. `readBytes` is a bounded read-only byte contract up to 8 MB;
+  write streaming is deferred.
 - Live watcher refresh is active while Verstak is running and a vault is open.
   It performs an initial no-event snapshot, then publishes `file.changed` for
   external creates, updates, and deletes outside `.verstak/`. It does not keep a
@@ -540,6 +543,7 @@ bundled runtime. Это реальный runtime contract для cooperative bun
 | `api.files.list(relativeDir)` | ✅ Работает | Список vault-relative директории, `.verstak` скрыта |
 | `api.files.metadata(relativePath)` | ✅ Работает | Metadata для файла/папки/symlink без чтения содержимого |
 | `api.files.readText(relativePath)` | ✅ Работает | Читает UTF-8 regular file до 2 MB |
+| `api.files.readBytes(relativePath)` | ✅ Работает | Читает regular file до 8 MB как base64 payload |
 | `api.files.writeText(relativePath, content, options)` | ✅ Работает | Atomic text write с явным create/overwrite policy |
 | `api.files.createFolder(relativePath)` | ✅ Работает | Создаёт vault-relative folder |
 | `api.files.move(from, to, options)` | ✅ Работает | Move file/folder с conflict и path-policy checks |

frontend/src/lib/plugin-host/VerstakPluginAPI.js

@@ -242,6 +242,12 @@ export function createPluginAPI(pluginId) {
           return App.ReadVaultTextFile(pluginId, relativePath);
         });
       },
+      readBytes: function(relativePath) {
+        assertActive('files.readBytes(' + relativePath + ')');
+        return callBackend(pluginId, 'files.readBytes(' + relativePath + ')', function() {
+          return App.ReadVaultFileBytes(pluginId, relativePath);
+        });
+      },
       writeText: function(relativePath, content, options) {
         assertActive('files.writeText(' + relativePath + ')');
         return callBackendErrorString(pluginId, 'files.writeText(' + relativePath + ')', function() {

frontend/src/lib/test/wails-mock.js

@@ -1287,6 +1287,23 @@
       if (node.type !== 'file') return Promise.resolve(['', 'not-regular-file: ' + norm.path]);
       return Promise.resolve([node.content || '', '']);
     },
+    ReadVaultFileBytes: function (pluginId, relativePath) {
+      var err = requirePluginPermission(pluginId, 'files.read');
+      if (err) return Promise.resolve([{}, err]);
+      var norm = normalizeVaultPath(relativePath, false);
+      if (norm.error) return Promise.resolve([{}, norm.error]);
+      var node = vaultFiles[norm.path];
+      if (!node) return Promise.resolve([{}, 'not-found: ' + norm.path]);
+      if (node.type !== 'file') return Promise.resolve([{}, 'not-regular-file: ' + norm.path]);
+      var content = node.content || '';
+      var dataBase64 = typeof btoa === 'function' ? btoa(content) : '';
+      return Promise.resolve([{
+        relativePath: norm.path,
+        size: content.length,
+        mimeHint: norm.path.toLowerCase().endsWith('.png') ? 'image/png' : '',
+        dataBase64: dataBase64
+      }, '']);
+    },
     WriteVaultTextFile: function (pluginId, relativePath, content, options) {
       var err = requirePluginPermission(pluginId, 'files.write');
       if (err) return Promise.resolve(err);

frontend/tests/plugin-api-files-test.mjs

@@ -11,8 +11,12 @@ globalThis.window = {
   go: {
     api: {
       App: {
+        ReadVaultFileBytes: (pluginId, relativePath) => {
+          calls.push({ method: 'ReadVaultFileBytes', pluginId, relativePath });
+          return Promise.resolve([{ relativePath, size: 4, mimeHint: 'image/png', dataBase64: 'iVBORw==' }, '']);
+        },
         RestoreVaultTrash: (pluginId, trashId, options) => {
-          calls.push({ pluginId, trashId, options });
+          calls.push({ method: 'RestoreVaultTrash', pluginId, trashId, options });
           return Promise.resolve(['Docs/restored.txt', '']);
         },
       },
@@ -33,12 +37,23 @@ const api = apiModule.createPluginAPI('verstak.files');
 if (!api.files || typeof api.files.restoreTrash !== 'function') {
   throw new Error('api.files.restoreTrash is missing');
 }
+if (typeof api.files.readBytes !== 'function') {
+  throw new Error('api.files.readBytes is missing');
+}
+
+const bytes = await api.files.readBytes('Docs/image.png');
+if (bytes.dataBase64 !== 'iVBORw==' || bytes.mimeHint !== 'image/png') {
+  throw new Error(`unexpected readBytes result: ${JSON.stringify(bytes)}`);
+}
 
 const restored = await api.files.restoreTrash('trash-1', { overwrite: true });
 if (restored !== 'Docs/restored.txt') {
   throw new Error(`unexpected restore result: ${JSON.stringify(restored)}`);
 }
-if (calls.length !== 1 || calls[0].pluginId !== 'verstak.files' || calls[0].trashId !== 'trash-1' || calls[0].options.overwrite !== true) {
+if (calls.length !== 2 || calls[0].method !== 'ReadVaultFileBytes' || calls[0].pluginId !== 'verstak.files' || calls[0].relativePath !== 'Docs/image.png') {
+  throw new Error(`unexpected ReadVaultFileBytes call: ${JSON.stringify(calls)}`);
+}
+if (calls[1].method !== 'RestoreVaultTrash' || calls[1].pluginId !== 'verstak.files' || calls[1].trashId !== 'trash-1' || calls[1].options.overwrite !== true) {
   throw new Error(`unexpected RestoreVaultTrash call: ${JSON.stringify(calls)}`);
 }
 

frontend/wailsjs/go/api/App.d.ts

@@ -102,18 +102,20 @@ export function ReadPluginSetting(arg1:string,arg2:string):Promise<any>;
 
 export function ReadPluginSettings(arg1:string):Promise<Record<string, any>|string>;
 
+export function ReadVaultFileBytes(arg1:string,arg2:string):Promise<files.FileBytes|string>;
+
 export function ReadVaultTextFile(arg1:string,arg2:string):Promise<string|string>;
 
 export function RecordDesiredPlugin(arg1:string,arg2:string,arg3:string):Promise<string>;
 
 export function ReloadPlugins():Promise<number|string>;
 
-export function RestoreVaultTrash(arg1:string,arg2:string,arg3:files.RestoreOptions):Promise<string|string>;
-
 export function RenameWorkspace(arg1:string,arg2:string):Promise<string>;
 
 export function RenameWorkspaceNode(arg1:string,arg2:string):Promise<string>;
 
+export function RestoreVaultTrash(arg1:string,arg2:string,arg3:files.RestoreOptions):Promise<string|string>;
+
 export function SelectDirectory():Promise<string>;
 
 export function SelectVaultForOpen():Promise<string>;

frontend/wailsjs/go/api/App.js

@@ -190,6 +190,10 @@ export function ReadPluginSettings(arg1) {
   return window['go']['api']['App']['ReadPluginSettings'](arg1);
 }
 
+export function ReadVaultFileBytes(arg1, arg2) {
+  return window['go']['api']['App']['ReadVaultFileBytes'](arg1, arg2);
+}
+
 export function ReadVaultTextFile(arg1, arg2) {
   return window['go']['api']['App']['ReadVaultTextFile'](arg1, arg2);
 }
@@ -202,10 +206,6 @@ export function ReloadPlugins() {
   return window['go']['api']['App']['ReloadPlugins']();
 }
 
-export function RestoreVaultTrash(arg1, arg2, arg3) {
-  return window['go']['api']['App']['RestoreVaultTrash'](arg1, arg2, arg3);
-}
-
 export function RenameWorkspace(arg1, arg2) {
   return window['go']['api']['App']['RenameWorkspace'](arg1, arg2);
 }
@@ -214,6 +214,10 @@ export function RenameWorkspaceNode(arg1, arg2) {
   return window['go']['api']['App']['RenameWorkspaceNode'](arg1, arg2);
 }
 
+export function RestoreVaultTrash(arg1, arg2, arg3) {
+  return window['go']['api']['App']['RestoreVaultTrash'](arg1, arg2, arg3);
+}
+
 export function SelectDirectory() {
   return window['go']['api']['App']['SelectDirectory']();
 }

frontend/wailsjs/go/models.ts

@@ -369,6 +369,24 @@ export namespace capability {
 
 export namespace files {
 	
+	export class FileBytes {
+	    relativePath: string;
+	    size: number;
+	    mimeHint: string;
+	    dataBase64: string;
+	
+	    static createFrom(source: any = {}) {
+	        return new FileBytes(source);
+	    }
+	
+	    constructor(source: any = {}) {
+	        if ('string' === typeof source) source = JSON.parse(source);
+	        this.relativePath = source["relativePath"];
+	        this.size = source["size"];
+	        this.mimeHint = source["mimeHint"];
+	        this.dataBase64 = source["dataBase64"];
+	    }
+	}
 	export class FileEntry {
 	    name: string;
 	    relativePath: string;

internal/api/app.go

@@ -876,6 +876,21 @@ func (a *App) ReadVaultTextFile(pluginID, relativePath string) (string, string)
 	return text, ""
 }
 
+// ReadVaultFileBytes reads a bounded regular file as base64 for a plugin with files.read.
+func (a *App) ReadVaultFileBytes(pluginID, relativePath string) (corefiles.FileBytes, string) {
+	if _, err := a.requirePluginAccess(pluginID, "files.read"); err != nil {
+		return corefiles.FileBytes{}, err.Error()
+	}
+	if a.files == nil {
+		return corefiles.FileBytes{}, "files service not initialized"
+	}
+	data, err := a.files.ReadVaultFileBytes(relativePath)
+	if err != nil {
+		return corefiles.FileBytes{}, err.Error()
+	}
+	return data, ""
+}
+
 // WriteVaultTextFile atomically writes a UTF-8 text file for a plugin with files.write.
 func (a *App) WriteVaultTextFile(pluginID, relativePath string, content string, options corefiles.WriteOptions) string {
 	if _, err := a.requirePluginAccess(pluginID, "files.write"); err != nil {

internal/api/app_test.go

@@ -360,11 +360,29 @@ func TestFilesBridgeReadWriteListMoveTrash(t *testing.T) {
 		t.Fatalf("text = %q", text)
 	}
 
+	if err := os.WriteFile(filepath.Join(root, "Docs", "image.png"), []byte{0x89, 0x50, 0x4e, 0x47}, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	bytesResult, errStr := app.ReadVaultFileBytes("files.plugin", "Docs/image.png")
+	if errStr != "" {
+		t.Fatalf("ReadVaultFileBytes: %s", errStr)
+	}
+	if bytesResult.RelativePath != "Docs/image.png" || bytesResult.MimeHint != "image/png" || bytesResult.DataBase64 != "iVBORw==" {
+		t.Fatalf("bytes result = %+v", bytesResult)
+	}
+
 	entries, errStr := app.ListVaultFiles("files.plugin", "Docs")
 	if errStr != "" {
 		t.Fatalf("ListVaultFiles: %s", errStr)
 	}
-	if len(entries) != 1 || entries[0].RelativePath != "Docs/one.txt" {
+	hasOne := false
+	for _, entry := range entries {
+		if entry.RelativePath == "Docs/one.txt" {
+			hasOne = true
+			break
+		}
+	}
+	if !hasOne {
 		t.Fatalf("entries = %+v", entries)
 	}
 
@@ -594,6 +612,12 @@ func TestFilesBridgePermissions(t *testing.T) {
 			call:       func(app *App) string { _, errStr := app.ReadVaultTextFile("files.plugin", "one.txt"); return errStr },
 			wantPhrase: "files.read",
 		},
+		{
+			name:       "read bytes requires read",
+			perms:      []string{"files.write", "files.delete"},
+			call:       func(app *App) string { _, errStr := app.ReadVaultFileBytes("files.plugin", "one.txt"); return errStr },
+			wantPhrase: "files.read",
+		},
 		{
 			name:  "write requires write",
 			perms: []string{"files.read", "files.delete"},

internal/core/files/service.go

@@ -1,6 +1,7 @@
 package files
 
 import (
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io/fs"
@@ -148,6 +149,42 @@ func (s *Service) ReadVaultTextFile(relativePath string) (string, error) {
 	return string(data), nil
 }
 
+func (s *Service) ReadVaultFileBytes(relativePath string) (FileBytes, error) {
+	root, rel, full, err := s.resolveFile(relativePath)
+	if err != nil {
+		return FileBytes{}, err
+	}
+	if err := rejectSymlinkPath(root, rel, true); err != nil {
+		return FileBytes{}, err
+	}
+	info, err := os.Lstat(full)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return FileBytes{}, fmt.Errorf("not-found: %s", rel)
+		}
+		return FileBytes{}, err
+	}
+	if info.Mode()&os.ModeSymlink != 0 {
+		return FileBytes{}, fmt.Errorf("symlink-not-allowed: %s", rel)
+	}
+	if !info.Mode().IsRegular() {
+		return FileBytes{}, fmt.Errorf("not-regular-file: %s", rel)
+	}
+	if info.Size() > MaxBinaryReadBytes {
+		return FileBytes{}, fmt.Errorf("file-too-large: %s", rel)
+	}
+	data, err := os.ReadFile(full)
+	if err != nil {
+		return FileBytes{}, err
+	}
+	return FileBytes{
+		RelativePath: rel,
+		Size:         int64(len(data)),
+		MimeHint:     mime.TypeByExtension(filepath.Ext(info.Name())),
+		DataBase64:   base64.StdEncoding.EncodeToString(data),
+	}, nil
+}
+
 func (s *Service) WriteVaultTextFile(relativePath string, content string, options WriteOptions) error {
 	root, rel, full, err := s.resolveFile(relativePath)
 	if err != nil {

internal/core/files/service_test.go

@@ -87,6 +87,9 @@ func TestPathPolicyRejectsUnsafeOperations(t *testing.T) {
 			if _, err := s.ReadVaultTextFile(input); err == nil {
 				t.Fatal("read: expected error")
 			}
+			if _, err := s.ReadVaultFileBytes(input); err == nil {
+				t.Fatal("read bytes: expected error")
+			}
 			if err := s.WriteVaultTextFile(input, "x", WriteOptions{CreateIfMissing: true}); err == nil {
 				t.Fatal("write: expected error")
 			}
@@ -137,6 +140,47 @@ func TestReadVaultTextFileRules(t *testing.T) {
 	}
 }
 
+func TestReadVaultFileBytesRules(t *testing.T) {
+	s, root := newTestService(t)
+	imageBytes := []byte{0x89, 0x50, 0x4e, 0x47}
+	if err := os.WriteFile(filepath.Join(root, "image.png"), imageBytes, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Mkdir(filepath.Join(root, "Folder"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "huge.bin"), []byte(strings.Repeat("a", int(MaxBinaryReadBytes)+1)), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	result, err := s.ReadVaultFileBytes("image.png")
+	if err != nil {
+		t.Fatalf("ReadVaultFileBytes image: %v", err)
+	}
+	if result.RelativePath != "image.png" {
+		t.Fatalf("relative path = %q, want image.png", result.RelativePath)
+	}
+	if result.Size != int64(len(imageBytes)) {
+		t.Fatalf("size = %d, want %d", result.Size, len(imageBytes))
+	}
+	if result.MimeHint != "image/png" {
+		t.Fatalf("mime hint = %q, want image/png", result.MimeHint)
+	}
+	if result.DataBase64 != "iVBORw==" {
+		t.Fatalf("dataBase64 = %q, want iVBORw==", result.DataBase64)
+	}
+
+	if _, err := s.ReadVaultFileBytes("Folder"); err == nil || !strings.Contains(err.Error(), "not-regular-file") {
+		t.Fatalf("read folder error = %v, want not-regular-file", err)
+	}
+	if _, err := s.ReadVaultFileBytes("missing.png"); err == nil || !strings.Contains(err.Error(), "not-found") {
+		t.Fatalf("read missing error = %v, want not-found", err)
+	}
+	if _, err := s.ReadVaultFileBytes("huge.bin"); err == nil || !strings.Contains(err.Error(), "file-too-large") {
+		t.Fatalf("read huge error = %v, want file-too-large", err)
+	}
+}
+
 func TestWriteVaultTextFileAtomicAndConflictBehavior(t *testing.T) {
 	s, root := newTestService(t)
 

internal/core/files/types.go

@@ -1,6 +1,7 @@
 package files
 
 const MaxTextFileBytes int64 = 2 * 1024 * 1024
+const MaxBinaryReadBytes int64 = 8 * 1024 * 1024
 
 type FileType string
 
@@ -39,6 +40,13 @@ type FileMetadata struct {
 	CanWrite     bool     `json:"canWrite"`
 }
 
+type FileBytes struct {
+	RelativePath string `json:"relativePath"`
+	Size         int64  `json:"size"`
+	MimeHint     string `json:"mimeHint"`
+	DataBase64   string `json:"dataBase64"`
+}
+
 type ExternalOpenTarget struct {
 	RelativePath string       `json:"relativePath"`
 	AbsolutePath string       `json:"absolutePath"`