Hmbown/CodeWhale · error · ExecError

low-level press/release is not exposed by uitest uiInput…

Error message

low-level press/release is not exposed by uitest uiInput; use left_click_drag

What it means

The harmony backend exposes drags only through uitest's `swipe` sub-command (left_click_drag). There is no press-and-hold primitive, so `left_mouse_down` throws this ExecError directing callers to left_click_drag. It is an intentional fail-fast for the press half of the low-level mouse API.

Solutions

  1. Rewrite the gesture as a single left_click_drag({ from_target, to }) — the backend implements it as uitest swipe and is the fix the message names.
  2. For press-and-hold semantics (not movement), use perform_action({ target, action: "longClick" }) or hold_key({ text: "click" }).
  3. Buffer intermediate move points and collapse the down/move/up sequence into one drag call before dispatching to a harmony backend.
  4. If fine-grained path control is required, chain multiple left_click_drag calls along the path, or add a press/release primitive to harmonyos.mjs only if uitest grows one.

Example fix

// before
await backend.left_mouse_down({ target: from });
await backend.mouse_move({ target: to });
await backend.left_mouse_up({});

// after
await backend.left_click_drag({ from_target: from, to });
Defensive patterns

Strategy: fallback

Validate before calling

const supportsLowLevelMouse = (backend) => backend.kind !== "harmonyos";
if (!supportsLowLevelMouse(backend)) {
  throw new Error("use left_click_drag on harmony; no press primitive");
}

Type guard

const hasPressPrimitive = (backend) => typeof backend.left_click_drag === "function" && backend.kind !== "harmonyos";

Try / catch

try {
  await backend.left_mouse_down({ target });
} catch (e) {
  if (/low-level press\/release is not exposed/.test(e.message)) {
    // redo the gesture as an atomic drag instead
    await backend.left_click_drag({ from_target: from, to });
  } else {
    throw e;
  }
}

Prevention

When it happens

Trigger: Calling the left_mouse_down action ({ action: "left_mouse_down" }) on the harmony backend from harmonyos.mjs; custom drag loops that sequence left_mouse_down → mouse_move → left_mouse_up.

Common situations: Porting a desktop drag implementation that builds drags from raw down/move/up events; agents emitting granular mouse primitives; interaction frameworks that assume a full low-level mouse API on every backend.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of Hmbown/CodeWhale@73e0f67d83 (2026-09-22). Data as JSON: /api/errors/f2bc3087e8cfc415. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/plugins/computer-use/src/backends/harmonyos.mjs:229

      const buf = fs.readFileSync(file);
      displayPixels = jpegSize(buf) ?? displayPixels;
      return { file, bytes: buf.length, pixels: jpegSize(buf), scale: 1, points: jpegSize(buf) };
    },
    zoom: async ({ region, path: outPath }) => {
      throw new ExecError("zoom is not supported on the harmony backend yet — screenshot + region on the host is the workaround");
    },
    left_click: ({ target, strategy }) => { assertEventStrategy(strategy); return uiInput(["click", String(Math.round(target.x)), String(Math.round(target.y))]); },
    double_click: ({ target }) => uiInput(["doubleClick", String(Math.round(target.x)), String(Math.round(target.y))]),
    triple_click: async ({ target }) => {
      await uiInput(["doubleClick", String(Math.round(target.x)), String(Math.round(target.y))]);
      return uiInput(["click", String(Math.round(target.x)), String(Math.round(target.y))]);
    },
    right_click: async () => { throw new ExecError("uitest uiInput has no right-click; use longClick semantics via hold or left_click"); },
    middle_click: async () => { throw new ExecError("middle click is not exposed by uitest uiInput"); },
    mouse_move: async () => ({ action_sent: false, note: "hover without press is not exposed by uitest uiInput" }),
    left_click_drag: ({ from_target: from, to }) =>
      uiInput(["swipe", String(Math.round(from.x)), String(Math.round(from.y)), String(Math.round(to.x)), String(Math.round(to.y)), "200"], { timeoutMs: 30_000 }),
    left_mouse_down: async () => { throw new ExecError("low-level press/release is not exposed by uitest uiInput; use left_click_drag"); },
    left_mouse_up: async () => { throw new ExecError("low-level press/release is not exposed by uitest uiInput; use left_click_drag"); },
    scroll: ({ target, direction = "down", amount = 300 }) => {
      const dist = Math.max(60, Math.min(1200, amount * 24));
      const dx = direction === "left" ? dist : direction === "right" ? -dist : 0;
      const dy = direction === "up" ? dist : direction === "down" ? -dist : 0;
      return uiInput(["swipe", String(Math.round(target.x)), String(Math.round(target.y)), String(Math.round(target.x + dx)), String(Math.round(target.y + dy)), "400"]);
    },
    type: async ({ text }) => {
      if (!text) return { action_sent: false, note: "empty text" };
      await uiInput(["inputText", "300", "300", escDeviceText(text)]).catch(async (e) => {
        // Some builds require coordinates of the focused field; retry with a click-first pattern.
        throw e;
      });
      return { action_sent: true, chars: text.length, note: "inputText at 300,300 — click the field first for focused input" };
    },
    key: ({ text }) => {
      const KEYMAP = { enter: "Enter", return: "Enter", escape: "Esc", esc: "Esc", back: "Back", home: "Home", backspace: "Back", delete: "Del", tab: "Tab", left: "DPAD_LEFT", right: "DPAD_RIGHT", up: "DPAD_UP", down: "DPAD_DOWN", power: "Power", menu: "Menu" };
      const k = KEYMAP[String(text).toLowerCase()] ?? String(text);

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