base

evals/diff-edits/diff-apply/diff-06-26-25.ts

@@ -492,6 +492,12 @@ async function constructNewFileContentV1(diffContent: string, originalContent: s
 		if (isReplaceBlockEnd(line)) {
 			// Finished one replace block
 
+			if (searchMatchIndex === -1) {
+				throw new Error(
+					`The SEARCH block:\n${currentSearchContent.trimEnd()}\n...is malformatted.`,
+				)
+			}
+
 			// Store this replacement
 			replacements.push({
 				start: searchMatchIndex,

src/core/assistant-message/diff.test.ts

@@ -156,6 +156,45 @@ replaced
 			expected: "line2\nreplaced\nline4",
 			isFinal: true,
 		},
+		{
+			name: "malformed diff - missing separator",
+			original: "line1\nline2\nline3",
+			diff: `------- SEARCH
+line2
++++++++ REPLACE
+replaced`,
+			shouldThrow: true,
+		},
+		{
+			name: "malformed diff - trailing space on separator",
+			original: "line1\nline2\nline3",
+			diff: `------- SEARCH
+line2
+======= 
+replaced
++++++++ REPLACE`,
+			shouldThrow: true,
+		},
+		{
+			name: "malformed diff - double replace markers",
+			original: "line1\nline2\nline3",
+			diff: `------- SEARCH
+line2
++++++++ REPLACE
+first replacement
++++++++ REPLACE`,
+			shouldThrow: true,
+		},
+		{
+			name: "malformed diff - malformed separator with dashes",
+			original: "line1\nline2\nline3",
+			diff: `------- SEARCH
+line2
+------- =======
+replaced
++++++++ REPLACE`,
+			shouldThrow: true,
+		},
 	]
 	//.filter(({name}) => name === "multiple ordered replacements")
 	//.filter(({name}) => name === "delete then replace")

src/core/assistant-message/diff.ts

@@ -380,6 +380,10 @@ async function constructNewFileContentV1(diffContent: string, originalContent: s
 		if (isReplaceBlockEnd(line)) {
 			// Finished one replace block
 
+			if (searchMatchIndex === -1) {
+				throw new Error(`The SEARCH block:\n${currentSearchContent.trimEnd()}\n...is malformatted.`)
+			}
+
 			// Store this replacement
 			replacements.push({
 				start: searchMatchIndex,