feat: add optional line range params to read_file tool (#2516)

AGENTS.md

@@ -283,6 +283,10 @@ When rebasing a branch that has drizzle migrations conflicting with upstream (e.
 4. Create/update the snapshot file (`drizzle/meta/00XX_snapshot.json`) with the new index, updating `prevId` to reference the previous snapshot's `id`
 5. If the PR had subsequent commits that deleted/modified its migration files, those changes become no-ops after renaming — just accept the deletion conflicts by staging the renamed files
 
+### tsgo is stricter than tsc for type checking
+
+The pre-commit hook runs `tsgo` (via `npm run ts`), which is stricter than `tsc --noEmit`. For example, passing a `number` to a function typed `(str: string | null | undefined)` may pass `tsc` but fail `tsgo` with `TS2345: Argument of type 'number' is not assignable to parameter of type 'string'`. Always wrap with `String()` when converting numbers to string parameters.
+
 ### OpenAI reasoning model errors with conversation history
 
 When using OpenAI reasoning models (o1, o3, o4-mini) via LiteLLM/Azure, you may see:

e2e-tests/snapshots/local_agent_ask.spec.ts_local-agent-ask-mode-1.txt

@@ -61,6 +61,18 @@
               "path": {
                 "type": "string",
                 "description": "The file path to read"
+              },
+              "start_line_one_indexed": {
+                "description": "The one-indexed line number to start reading from (inclusive).",
+                "type": "integer",
+                "minimum": 1,
+                "maximum": 9007199254740991
+              },
+              "end_line_one_indexed_inclusive": {
+                "description": "The one-indexed line number to end reading at (inclusive).",
+                "type": "integer",
+                "minimum": 1,
+                "maximum": 9007199254740991
               }
             },
             "required": [

e2e-tests/snapshots/local_agent_auto.spec.ts_local-agent---auto-model-1.txt

@@ -201,6 +201,18 @@
             "path": {
               "type": "string",
               "description": "The file path to read"
+            },
+            "start_line_one_indexed": {
+              "description": "The one-indexed line number to start reading from (inclusive).",
+              "type": "integer",
+              "minimum": 1,
+              "maximum": 9007199254740991
+            },
+            "end_line_one_indexed_inclusive": {
+              "description": "The one-indexed line number to end reading at (inclusive).",
+              "type": "integer",
+              "minimum": 1,
+              "maximum": 9007199254740991
             }
           },
           "required": [
@@ -482,6 +494,7 @@
     "include": [
       "reasoning.encrypted_content"
     ],
+    "store": false,
     "dyad_options": {
       "enable_lazy_edits": true,
       "enable_smart_files_context": true

e2e-tests/snapshots/local_agent_basic.spec.ts_local-agent---dump-request-1.txt

@@ -196,6 +196,18 @@
               "path": {
                 "type": "string",
                 "description": "The file path to read"
+              },
+              "start_line_one_indexed": {
+                "description": "The one-indexed line number to start reading from (inclusive).",
+                "type": "integer",
+                "minimum": 1,
+                "maximum": 9007199254740991
+              },
+              "end_line_one_indexed_inclusive": {
+                "description": "The one-indexed line number to end reading at (inclusive).",
+                "type": "integer",
+                "minimum": 1,
+                "maximum": 9007199254740991
               }
             },
             "required": [

src/ipc/utils/versioned_codebase_context.ts

@@ -40,7 +40,7 @@ export function parseFilesFromMessage(content: string): string[] {
   const matches: TagMatch[] = [];
 
   // Parse <dyad-read path="$filePath"></dyad-read>
-  const dyadReadRegex = /<dyad-read\s+path="([^"]+)"\s*><\/dyad-read>/gs;
+  const dyadReadRegex = /<dyad-read\s+path="([^"]+)"[^>]*><\/dyad-read>/gs;
   let match: RegExpExecArray | null;
   while ((match = dyadReadRegex.exec(content)) !== null) {
     const filePath = normalizePath(match[1].trim());

src/pro/main/ipc/handlers/local_agent/tools/read_file.ts

@@ -5,9 +5,41 @@ import { safeJoin } from "@/ipc/utils/path_utils";
 
 const readFile = fs.promises.readFile;
 
-const readFileSchema = z.object({
-  path: z.string().describe("The file path to read"),
-});
+const readFileSchema = z
+  .object({
+    path: z.string().describe("The file path to read"),
+    start_line_one_indexed: z
+      .number()
+      .int()
+      .min(1)
+      .optional()
+      .describe(
+        "The one-indexed line number to start reading from (inclusive).",
+      ),
+    end_line_one_indexed_inclusive: z
+      .number()
+      .int()
+      .min(1)
+      .optional()
+      .describe("The one-indexed line number to end reading at (inclusive)."),
+  })
+  .refine(
+    (data) => {
+      if (
+        data.start_line_one_indexed != null &&
+        data.end_line_one_indexed_inclusive != null
+      ) {
+        return (
+          data.start_line_one_indexed <= data.end_line_one_indexed_inclusive
+        );
+      }
+      return true;
+    },
+    {
+      message:
+        "start_line_one_indexed must be <= end_line_one_indexed_inclusive",
+    },
+  );
 
 export const readFileTool: ToolDefinition<z.infer<typeof readFileSchema>> = {
   name: "read_file",
@@ -17,11 +49,33 @@ export const readFileTool: ToolDefinition<z.infer<typeof readFileSchema>> = {
   inputSchema: readFileSchema,
   defaultConsent: "always",
 
-  getConsentPreview: (args) => `Read ${args.path}`,
+  getConsentPreview: (args) => {
+    const start = args.start_line_one_indexed;
+    const end = args.end_line_one_indexed_inclusive;
+    if (start != null && end != null) {
+      return `Read ${args.path} (lines ${start}-${end})`;
+    } else if (start != null) {
+      return `Read ${args.path} (from line ${start})`;
+    } else if (end != null) {
+      return `Read ${args.path} (to line ${end})`;
+    }
+    return `Read ${args.path}`;
+  },
 
   buildXml: (args, _isComplete) => {
     if (!args.path) return undefined;
-    return `<dyad-read path="${escapeXmlAttr(args.path)}"></dyad-read>`;
+    const attrs = [`path="${escapeXmlAttr(args.path)}"`];
+    if (args.start_line_one_indexed != null) {
+      attrs.push(
+        `start_line="${escapeXmlAttr(String(args.start_line_one_indexed))}"`,
+      );
+    }
+    if (args.end_line_one_indexed_inclusive != null) {
+      attrs.push(
+        `end_line="${escapeXmlAttr(String(args.end_line_one_indexed_inclusive))}"`,
+      );
+    }
+    return `<dyad-read ${attrs.join(" ")}></dyad-read>`;
   },
 
   execute: async (args, ctx: AgentContext) => {
@@ -32,6 +86,24 @@ export const readFileTool: ToolDefinition<z.infer<typeof readFileSchema>> = {
     }
 
     const content = await readFile(fullFilePath, "utf8");
-    return content || "";
+    if (!content) return "";
+
+    const start = args.start_line_one_indexed;
+    const end = args.end_line_one_indexed_inclusive;
+
+    if (start == null && end == null) {
+      return content;
+    }
+
+    const hasTrailingNewline = content.endsWith("\n");
+    const lines = (hasTrailingNewline ? content.slice(0, -1) : content).split(
+      "\n",
+    );
+    const startIdx = Math.max(0, (start ?? 1) - 1);
+    const endIdx = Math.min(lines.length, end ?? lines.length);
+    const result = lines.slice(startIdx, endIdx).join("\n");
+    return endIdx >= lines.length && hasTrailingNewline
+      ? result + "\n"
+      : result;
   },
 };