@@ -762,7 +762,7 @@ describe("ClineProvider.delegateParentAndOpenChild()", () => {
 		expect(durableParent.awaitingChildId).toBe("child-1")
 	})
 
-	it.each(["legacy", "pending", "flushed", "resolved", "read-failure", "write-failure"] as const)(
+	it.each(["legacy", "pending", "flushed", "resolved", "missing-tool-use", "read-failure", "write-failure"] as const)(
 		"rolls back without automatic action replay after a metadata failure (%s)",
 		async (scenario) => {
 			const persistError = new Error("parent metadata persist failed")
@@ -803,6 +803,10 @@ describe("ClineProvider.delegateParentAndOpenChild()", () => {
 					],
 				})
 			}
+			if (scenario === "missing-tool-use") {
+				// No owning tool_use: a standalone tool_result would be rejected by native tool-call providers.
+				durableMessages = []
+			}
 			if (scenario === "resolved") {
 				durableMessages.push({
 					role: "user",
@@ -893,7 +897,7 @@ describe("ClineProvider.delegateParentAndOpenChild()", () => {
 			expect(removeClineFromStack).toHaveBeenNthCalledWith(1)
 			expect(removeClineFromStack).toHaveBeenNthCalledWith(2)
 			expect(deleteTaskWithId).toHaveBeenCalledWith("child-1", false)
-			if (scenario === "read-failure" || scenario === "write-failure") {
+			if (scenario === "read-failure" || scenario === "write-failure" || scenario === "missing-tool-use") {
 				expect(createTaskWithHistoryItem).not.toHaveBeenCalled()
 			} else {
 				expect(createTaskWithHistoryItem).toHaveBeenCalledExactlyOnceWith(historyItem)
 
@@ -127,7 +127,13 @@ describe("TaskHistoryStore", () => {
 				await expect(store.invalidate("owner")).resolves.toBeUndefined()
 				expect(store.get("owner")).toBeUndefined()
 			} else {
-				await expect(store.invalidate("owner")).rejects.toThrow()
+				await expect(store.invalidate("owner")).rejects.toMatchObject(
+					scenario === "read-error"
+						? { code: "EISDIR" }
+						: scenario === "malformed"
+							? { name: "SyntaxError" }
+							: { message: expect.stringContaining("Invalid task history record") },
+				)
 				expect(store.get("owner")).toEqual(owner)
 			}
 		})
 
@@ -4049,7 +4049,14 @@ export class ClineProvider
 									(block) => block.type === "tool_use" && block.id === pendingActionId,
 								),
 						)
-						const nextMessage = toolUseIndex === -1 ? undefined : messages[toolUseIndex + 1]
+						// A standalone tool_result with no owning tool_use is invalid API history that
+						// native tool-call providers reject; leave the parent for an explicit retry instead.
+						if (toolUseIndex === -1) {
+							throw new Error(
+								`[delegateParentAndOpenChild] Cannot resolve pending action ${pendingActionId}: no matching tool_use exists`,
+							)
+						}
+						const nextMessage = messages[toolUseIndex + 1]
 						if (nextMessage?.role === "user") {
 							const content =
 								typeof nextMessage.content === "string"
@@ -4059,7 +4066,7 @@ export class ClineProvider
 							content.splice(firstNonTool === -1 ? content.length : firstNonTool, 0, result)
 							messages[toolUseIndex + 1] = { ...nextMessage, content }
 						} else {
-							messages.splice(toolUseIndex === -1 ? messages.length : toolUseIndex + 1, 0, {
+							messages.splice(toolUseIndex + 1, 0, {
 								role: "user",
 								ts: Date.now(),
 								content: [result],