fix: allow partial args through parseToolCall finalization for write_to_file and other tools

When the model response gets truncated (e.g., due to output token limits),
required parameters like `content` for write_to_file arrive as `undefined`.
The finalization path in parseToolCall() required ALL params via AND conditions,
causing nativeArgs to stay undefined and the tool call to be silently dropped
or throw a generic error -- bypassing the tool's own user-friendly retry logic.

The streaming/partial path already uses OR conditions to allow partial args
through. This change aligns the finalization path with the same pattern,
so that partially-constructed args flow through to the tool's execute() method,
which can produce specific "missing parameter X, retrying..." messages that
get sent back to the model.

Fixes #12079

src/core/assistant-message/NativeToolCallParser.ts

@@ -794,7 +794,7 @@ export class NativeToolCallParser {
 					break
 
 				case "apply_diff":
-					if (args.path !== undefined && args.diff !== undefined) {
+					if (args.path !== undefined || args.diff !== undefined) {
 						nativeArgs = {
 							path: args.path,
 							diff: args.diff,
@@ -805,8 +805,8 @@ export class NativeToolCallParser {
 				case "edit":
 				case "search_and_replace":
 					if (
-						args.file_path !== undefined &&
-						args.old_string !== undefined &&
+						args.file_path !== undefined ||
+						args.old_string !== undefined ||
 						args.new_string !== undefined
 					) {
 						nativeArgs = {
@@ -819,7 +819,7 @@ export class NativeToolCallParser {
 					break
 
 				case "ask_followup_question":
-					if (args.question !== undefined && args.follow_up !== undefined) {
+					if (args.question !== undefined || args.follow_up !== undefined) {
 						nativeArgs = {
 							question: args.question,
 							follow_up: args.follow_up,
@@ -837,7 +837,7 @@ export class NativeToolCallParser {
 					break
 
 				case "generate_image":
-					if (args.prompt !== undefined && args.path !== undefined) {
+					if (args.prompt !== undefined || args.path !== undefined) {
 						nativeArgs = {
 							prompt: args.prompt,
 							path: args.path,
@@ -865,7 +865,7 @@ export class NativeToolCallParser {
 					break
 
 				case "search_files":
-					if (args.path !== undefined && args.regex !== undefined) {
+					if (args.path !== undefined || args.regex !== undefined) {
 						nativeArgs = {
 							path: args.path,
 							regex: args.regex,
@@ -875,7 +875,7 @@ export class NativeToolCallParser {
 					break
 
 				case "switch_mode":
-					if (args.mode_slug !== undefined && args.reason !== undefined) {
+					if (args.mode_slug !== undefined || args.reason !== undefined) {
 						nativeArgs = {
 							mode_slug: args.mode_slug,
 							reason: args.reason,
@@ -903,7 +903,7 @@ export class NativeToolCallParser {
 					break
 
 				case "write_to_file":
-					if (args.path !== undefined && args.content !== undefined) {
+					if (args.path !== undefined || args.content !== undefined) {
 						nativeArgs = {
 							path: args.path,
 							content: args.content,
@@ -912,7 +912,7 @@ export class NativeToolCallParser {
 					break
 
 				case "use_mcp_tool":
-					if (args.server_name !== undefined && args.tool_name !== undefined) {
+					if (args.server_name !== undefined || args.tool_name !== undefined) {
 						nativeArgs = {
 							server_name: args.server_name,
 							tool_name: args.tool_name,
@@ -922,7 +922,7 @@ export class NativeToolCallParser {
 					break
 
 				case "access_mcp_resource":
-					if (args.server_name !== undefined && args.uri !== undefined) {
+					if (args.server_name !== undefined || args.uri !== undefined) {
 						nativeArgs = {
 							server_name: args.server_name,
 							uri: args.uri,
@@ -940,8 +940,8 @@ export class NativeToolCallParser {
 
 				case "search_replace":
 					if (
-						args.file_path !== undefined &&
-						args.old_string !== undefined &&
+						args.file_path !== undefined ||
+						args.old_string !== undefined ||
 						args.new_string !== undefined
 					) {
 						nativeArgs = {
@@ -954,8 +954,8 @@ export class NativeToolCallParser {
 
 				case "edit_file":
 					if (
-						args.file_path !== undefined &&
-						args.old_string !== undefined &&
+						args.file_path !== undefined ||
+						args.old_string !== undefined ||
 						args.new_string !== undefined
 					) {
 						nativeArgs = {
@@ -977,7 +977,7 @@ export class NativeToolCallParser {
 					break
 
 				case "new_task":
-					if (args.mode !== undefined && args.message !== undefined) {
+					if (args.mode !== undefined || args.message !== undefined) {
 						nativeArgs = {
 							mode: args.mode,
 							message: args.message,

src/core/assistant-message/__tests__/NativeToolCallParser.spec.ts

@@ -313,6 +313,91 @@ describe("NativeToolCallParser", () => {
 		})
 	})
 
+	describe("write_to_file tool", () => {
+		it("should parse write_to_file with both path and content", () => {
+			const toolCall = {
+				id: "toolu_wtf_1",
+				name: "write_to_file" as const,
+				arguments: JSON.stringify({
+					path: "src/test.ts",
+					content: "console.log('hello')",
+				}),
+			}
+
+			const result = NativeToolCallParser.parseToolCall(toolCall)
+
+			expect(result).not.toBeNull()
+			expect(result?.type).toBe("tool_use")
+			if (result?.type === "tool_use") {
+				const nativeArgs = result.nativeArgs as { path: string; content: string }
+				expect(nativeArgs.path).toBe("src/test.ts")
+				expect(nativeArgs.content).toBe("console.log('hello')")
+			}
+		})
+
+		it("should parse write_to_file with missing content (truncated response)", () => {
+			const toolCall = {
+				id: "toolu_wtf_2",
+				name: "write_to_file" as const,
+				arguments: JSON.stringify({
+					path: "src/test.ts",
+				}),
+			}
+
+			const result = NativeToolCallParser.parseToolCall(toolCall)
+
+			expect(result).not.toBeNull()
+			expect(result?.type).toBe("tool_use")
+			if (result?.type === "tool_use") {
+				const nativeArgs = result.nativeArgs as { path: string; content?: string }
+				expect(nativeArgs.path).toBe("src/test.ts")
+				expect(nativeArgs.content).toBeUndefined()
+			}
+		})
+
+		it("should parse write_to_file with missing path", () => {
+			const toolCall = {
+				id: "toolu_wtf_3",
+				name: "write_to_file" as const,
+				arguments: JSON.stringify({
+					content: "console.log('hello')",
+				}),
+			}
+
+			const result = NativeToolCallParser.parseToolCall(toolCall)
+
+			expect(result).not.toBeNull()
+			expect(result?.type).toBe("tool_use")
+			if (result?.type === "tool_use") {
+				const nativeArgs = result.nativeArgs as { path?: string; content: string }
+				expect(nativeArgs.path).toBeUndefined()
+				expect(nativeArgs.content).toBe("console.log('hello')")
+			}
+		})
+	})
+
+	describe("apply_diff tool with missing params", () => {
+		it("should parse apply_diff with missing diff (truncated response)", () => {
+			const toolCall = {
+				id: "toolu_ad_1",
+				name: "apply_diff" as const,
+				arguments: JSON.stringify({
+					path: "src/test.ts",
+				}),
+			}
+
+			const result = NativeToolCallParser.parseToolCall(toolCall)
+
+			expect(result).not.toBeNull()
+			expect(result?.type).toBe("tool_use")
+			if (result?.type === "tool_use") {
+				const nativeArgs = result.nativeArgs as { path: string; diff?: string }
+				expect(nativeArgs.path).toBe("src/test.ts")
+				expect(nativeArgs.diff).toBeUndefined()
+			}
+		})
+	})
+
 	describe("finalizeStreamingToolCall", () => {
 		describe("read_file tool", () => {
 			it("should parse read_file args on finalize", () => {