fix(ai): detect Ollama overflow errors closes #2626

packages/ai/test/overflow.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, it } from "vitest";
+import type { AssistantMessage } from "../src/types.js";
+import { isContextOverflow } from "../src/utils/overflow.js";
+
+function createErrorMessage(errorMessage: string): AssistantMessage {
+	return {
+		role: "assistant",
+		content: [],
+		api: "openai-completions",
+		provider: "ollama",
+		model: "qwen3.5:35b",
+		usage: {
+			input: 0,
+			output: 0,
+			cacheRead: 0,
+			cacheWrite: 0,
+			totalTokens: 0,
+			cost: {
+				input: 0,
+				output: 0,
+				cacheRead: 0,
+				cacheWrite: 0,
+				total: 0,
+			},
+		},
+		stopReason: "error",
+		errorMessage,
+		timestamp: Date.now(),
+	};
+}
+
+describe("isContextOverflow", () => {
+	it("detects explicit Ollama prompt-too-long errors", () => {
+		const message = createErrorMessage("400 `prompt too long; exceeded max context length by 100918 tokens`");
+		expect(isContextOverflow(message, 32768)).toBe(true);
+	});
+
+	it("does not treat generic non-overflow Ollama errors as overflow", () => {
+		const message = createErrorMessage("500 `model runner crashed unexpectedly`");
+		expect(isContextOverflow(message, 32768)).toBe(false);
+	});
+});