Guard non-positive mcp.timeoutMs to the default

Author: TheGreatAxios

src/tui/tool-execution-watchdog.test.ts

@@ -148,6 +148,19 @@ describe("tool execution watchdog", () => {
     ).toBe(100);
   });
 
+  test("non-positive or non-finite mcp.timeoutMs falls back to the default instead of a 1ms timeout", () => {
+    const call = { id: "1", name: "mcp__linear__get_issue", arguments: {} };
+    expect(resolveToolExecutionTimeoutMs({ mcpTimeoutMs: 0 }, call)).toBe(
+      DEFAULT_MCP_TOOL_TIMEOUT_MS,
+    );
+    expect(resolveToolExecutionTimeoutMs({ mcpTimeoutMs: -5 }, call)).toBe(
+      DEFAULT_MCP_TOOL_TIMEOUT_MS,
+    );
+    expect(resolveToolExecutionTimeoutMs({ mcpTimeoutMs: NaN }, call)).toBe(
+      DEFAULT_MCP_TOOL_TIMEOUT_MS,
+    );
+  });
+
   test("withTimeout dispose clears timer without leaving hung state", async () => {
     const parent = new AbortController();
     const budget = withTimeout(parent.signal, 50);
@@ -233,6 +246,23 @@ describe("tool execution watchdog", () => {
     10_000,
   );
 
+  test(
+    "mcp.timeoutMs: 0 does not instantly time out an mcp tool call (falls back to the default)",
+    async () => {
+      const runner = createDynamicToolRunner(
+        [stringTool("mcp__linear__get_issue", async () => "ok")],
+        { mcpTimeoutMs: 0 },
+      );
+      const result = await runner.run(
+        { id: "1", name: "mcp__linear__get_issue", arguments: {} },
+        new AbortController().signal,
+      );
+      expect(result.isError).toBeUndefined();
+      expect(result.content).toBe("ok");
+    },
+    10_000,
+  );
+
   test("parent cancel prefers execute salvage body over synthetic aborted", async () => {
     const parent = new AbortController();
     const salvage = {

src/tui/tool-execution-watchdog.ts

@@ -97,7 +97,14 @@ export function resolveToolExecutionTimeoutMs(
 
 function resolveMcpToolTimeoutMs(config: ToolWatchdogConfig | undefined): number {
   const max = config?.maxMs ?? MAX_TOOL_EXECUTION_TIMEOUT_MS;
-  const raw = config?.mcpTimeoutMs ?? DEFAULT_MCP_TOOL_TIMEOUT_MS;
+  const configured = config?.mcpTimeoutMs;
+  // A non-positive or non-finite configured value is not a valid budget (it
+  // would floor to a ~0ms timeout and instantly fail every MCP call, which is
+  // unconditionally armed) — fall back to the default instead of clamping to 1ms.
+  const raw =
+    configured !== undefined && Number.isFinite(configured) && configured > 0
+      ? configured
+      : DEFAULT_MCP_TOOL_TIMEOUT_MS;
   return Math.min(max, Math.max(1, Math.floor(raw)));
 }