From 5bf4eec3d8ae163fcda9b5c225abd87c54bdbf9b Mon Sep 17 00:00:00 2001
From: Roo Code <roomote@roocode.com>
Date: Sun, 21 Dec 2025 16:28:23 +0000
Subject: [PATCH 1/2] feat: improve context budget truncation notice with total
 lines and continuation example

When files are truncated due to context budget limits, the truncation notice now includes:
- Total number of lines in the file
- The next line number to continue from
- A concrete example of the line_range syntax

This helps models understand why they received fewer lines than expected and how to continue reading.

Addresses Issue #10239
---
 src/core/tools/ReadFileTool.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/core/tools/ReadFileTool.ts b/src/core/tools/ReadFileTool.ts
index 58f3cc495e1..b4ee651a6dd 100644
--- a/src/core/tools/ReadFileTool.ts
+++ b/src/core/tools/ReadFileTool.ts
@@ -547,8 +547,9 @@ export class ReadFileTool extends BaseTool<"read_file"> {
 						content = addLineNumbers(result.content)
 
 						if (!result.complete) {
-							// File was truncated
-							const notice = `File truncated: showing ${result.lineCount} lines (${result.tokenCount} tokens) due to context budget. Use line_range to read specific sections.`
+							// File was truncated due to context budget
+							const nextLine = result.lineCount + 1
+							const notice = `File truncated at line ${result.lineCount} of ${totalLines} total lines due to context budget (${result.tokenCount} tokens used). To continue reading, use the read_file tool again with line_range starting at line ${nextLine} (e.g., <line_range>${nextLine}-${Math.min(nextLine + 499, totalLines)}</line_range>)`
 							const lineRangeAttr = result.lineCount > 0 ? ` lines="1-${result.lineCount}"` : ""
 							xmlInfo =
 								result.lineCount > 0

From 6e9486964ef3afcb637461aa0b9255f8b3edc816 Mon Sep 17 00:00:00 2001
From: Roo Code <roomote@roocode.com>
Date: Sun, 21 Dec 2025 16:40:06 +0000
Subject: [PATCH 2/2] fix: update remaining truncation notices with concrete
 line_range examples

---
 src/core/tools/ReadFileTool.ts                | 5 +++--
 src/core/tools/__tests__/readFileTool.spec.ts | 6 +++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/core/tools/ReadFileTool.ts b/src/core/tools/ReadFileTool.ts
index b4ee651a6dd..0093e89e08d 100644
--- a/src/core/tools/ReadFileTool.ts
+++ b/src/core/tools/ReadFileTool.ts
@@ -458,7 +458,7 @@ export class ReadFileTool extends BaseTool<"read_file"> {
 								task.rooIgnoreController,
 							)
 							if (defResult) {
-								const notice = `Showing only ${maxReadFileLine} of ${totalLines} total lines. Use line_range if you need to read more lines`
+								const notice = `Showing code definitions only (0 of ${totalLines} total lines). To read file content, use the read_file tool with line_range (e.g., <line_range>1-${Math.min(500, totalLines)}</line_range>)`
 								updateFileResult(relPath, {
 									xmlContent: `<file><path>${relPath}</path>\n<list_code_definition_names>${defResult}</list_code_definition_names>\n<notice>${notice}</notice>\n</file>`,
 									nativeContent: `File: ${relPath}\nCode Definitions:\n${defResult}\n\nNote: ${notice}`,
@@ -493,7 +493,8 @@ export class ReadFileTool extends BaseTool<"read_file"> {
 								nativeInfo += `\nCode Definitions:\n${truncatedDefs}\n`
 							}
 
-							const notice = `Showing only ${maxReadFileLine} of ${totalLines} total lines. Use line_range if you need to read more lines`
+							const nextLine = maxReadFileLine + 1
+							const notice = `File truncated at line ${maxReadFileLine} of ${totalLines} total lines. To continue reading, use the read_file tool again with line_range starting at line ${nextLine} (e.g., <line_range>${nextLine}-${Math.min(nextLine + 499, totalLines)}</line_range>)`
 							xmlInfo += `<notice>${notice}</notice>\n`
 							nativeInfo += `\nNote: ${notice}`
 
diff --git a/src/core/tools/__tests__/readFileTool.spec.ts b/src/core/tools/__tests__/readFileTool.spec.ts
index d22c163636f..08b0edc7ade 100644
--- a/src/core/tools/__tests__/readFileTool.spec.ts
+++ b/src/core/tools/__tests__/readFileTool.spec.ts
@@ -423,7 +423,7 @@ describe("read_file tool with maxReadFileLine setting", () => {
 			expect(result).toContain(`<list_code_definition_names>`)
 
 			// Verify XML structure
-			expect(result).toContain("<notice>Showing only 0 of 5 total lines")
+			expect(result).toContain("<notice>Showing code definitions only (0 of 5 total lines)")
 			expect(result).toContain("</notice>")
 			expect(result).toContain("<list_code_definition_names>")
 			expect(result).toContain(sourceCodeDef.trim())
@@ -450,7 +450,7 @@ describe("read_file tool with maxReadFileLine setting", () => {
 			expect(result).toContain(`<file><path>${testFilePath}</path>`)
 			expect(result).toContain(`<content lines="1-3">`)
 			expect(result).toContain(`<list_code_definition_names>`)
-			expect(result).toContain("<notice>Showing only 3 of 5 total lines")
+			expect(result).toContain("<notice>File truncated at line 3 of 5 total lines")
 		})
 
 		it("should truncate code definitions when file exceeds maxReadFileLine", async () => {
@@ -481,7 +481,7 @@ describe("read_file tool with maxReadFileLine setting", () => {
 			expect(result).not.toContain("50--60 | function bar()")
 			expect(result).not.toContain("80--90 | function baz()")
 
-			expect(result).toContain("<notice>Showing only 30 of 100 total lines")
+			expect(result).toContain("<notice>File truncated at line 30 of 100 total lines")
 		})
 
 		it("should handle truncation when all definitions are beyond the line limit", async () => {