feat: add web search, file edit, MCP management, file refs, and /stop to CLI/TUI (#348)

apps/gateway/src/agent/tools/file-tools.ts

@@ -190,5 +190,169 @@ export function createFileTools(baseDir: string): ToolDefinition[] {
     },
   };
 
-  return [readFileTool, writeFileTool, listDirectoryTool];
+  const editFileTool: ToolDefinition = {
+    name: 'fs_edit_file',
+    label: 'Edit File',
+    description:
+      'Make targeted text replacements in a file. Each edit replaces an exact match of oldText with newText. ' +
+      'All edits are matched against the original file content (not incrementally). ' +
+      'Each oldText must be unique in the file and edits must not overlap.',
+    parameters: Type.Object({
+      path: Type.String({
+        description: 'File path (relative to sandbox base or absolute within it)',
+      }),
+      edits: Type.Array(
+        Type.Object({
+          oldText: Type.String({
+            description: 'Exact text to find and replace (must be unique in the file)',
+          }),
+          newText: Type.String({ description: 'Replacement text' }),
+        }),
+        { description: 'One or more targeted replacements', minItems: 1 },
+      ),
+    }),
+    async execute(_toolCallId, params) {
+      const { path, edits } = params as {
+        path: string;
+        edits: Array<{ oldText: string; newText: string }>;
+      };
+
+      let safePath: string;
+      try {
+        safePath = guardPath(path, baseDir);
+      } catch (err) {
+        if (err instanceof SandboxEscapeError) {
+          return {
+            content: [{ type: 'text' as const, text: `Error: ${err.message}` }],
+            details: undefined,
+          };
+        }
+        return {
+          content: [{ type: 'text' as const, text: `Error: ${String(err)}` }],
+          details: undefined,
+        };
+      }
+
+      try {
+        const info = await stat(safePath);
+        if (!info.isFile()) {
+          return {
+            content: [{ type: 'text' as const, text: `Error: path is not a file: ${path}` }],
+            details: undefined,
+          };
+        }
+        if (info.size > MAX_READ_BYTES) {
+          return {
+            content: [
+              {
+                type: 'text' as const,
+                text: `Error: file too large for editing (${info.size} bytes, limit ${MAX_READ_BYTES} bytes)`,
+              },
+            ],
+            details: undefined,
+          };
+        }
+      } catch (err) {
+        return {
+          content: [{ type: 'text' as const, text: `Error reading file: ${String(err)}` }],
+          details: undefined,
+        };
+      }
+
+      let content: string;
+      try {
+        content = await readFile(safePath, { encoding: 'utf8' });
+      } catch (err) {
+        return {
+          content: [{ type: 'text' as const, text: `Error reading file: ${String(err)}` }],
+          details: undefined,
+        };
+      }
+
+      // Validate all edits before applying any
+      const errors: string[] = [];
+      for (let i = 0; i < edits.length; i++) {
+        const edit = edits[i]!;
+        const occurrences = content.split(edit.oldText).length - 1;
+        if (occurrences === 0) {
+          errors.push(`Edit ${i + 1}: oldText not found in file`);
+        } else if (occurrences > 1) {
+          errors.push(`Edit ${i + 1}: oldText matches ${occurrences} locations (must be unique)`);
+        }
+      }
+
+      // Check for overlapping edits
+      if (errors.length === 0) {
+        const positions = edits.map((edit, i) => ({
+          index: i,
+          start: content.indexOf(edit.oldText),
+          end: content.indexOf(edit.oldText) + edit.oldText.length,
+        }));
+        positions.sort((a, b) => a.start - b.start);
+        for (let i = 1; i < positions.length; i++) {
+          if (positions[i]!.start < positions[i - 1]!.end) {
+            errors.push(
+              `Edits ${positions[i - 1]!.index + 1} and ${positions[i]!.index + 1} overlap`,
+            );
+          }
+        }
+      }
+
+      if (errors.length > 0) {
+        return {
+          content: [
+            {
+              type: 'text' as const,
+              text: `Edit validation failed:\n${errors.join('\n')}`,
+            },
+          ],
+          details: undefined,
+        };
+      }
+
+      // Apply edits: process from end to start to preserve positions
+      const positions = edits.map((edit) => ({
+        edit,
+        start: content.indexOf(edit.oldText),
+      }));
+      positions.sort((a, b) => b.start - a.start); // reverse order
+
+      let result = content;
+      for (const { edit } of positions) {
+        result = result.replace(edit.oldText, edit.newText);
+      }
+
+      if (Buffer.byteLength(result, 'utf8') > MAX_WRITE_BYTES) {
+        return {
+          content: [
+            {
+              type: 'text' as const,
+              text: `Error: resulting file too large (limit ${MAX_WRITE_BYTES} bytes)`,
+            },
+          ],
+          details: undefined,
+        };
+      }
+
+      try {
+        await writeFile(safePath, result, { encoding: 'utf8' });
+        return {
+          content: [
+            {
+              type: 'text' as const,
+              text: `File edited successfully: ${path} (${edits.length} edit(s) applied)`,
+            },
+          ],
+          details: undefined,
+        };
+      } catch (err) {
+        return {
+          content: [{ type: 'text' as const, text: `Error writing file: ${String(err)}` }],
+          details: undefined,
+        };
+      }
+    },
+  };
+
+  return [readFileTool, writeFileTool, listDirectoryTool, editFileTool];
 }