fix(core): replace numbered point callout with badge-neutral centered marker

[NianZheChao]

Summary


In the recorder's tap-to-describe flow, the model receives a screenshot with a temporary annotation marking the tapped point and is asked to describe the real UI element at that point. The old annotation was a red filled bubble with a white "1" digit connected by a leader line — visually near-identical to an Android notification badge. Vision-language models frequently described the annotation itself as if it were part of the page (e.g. "a back arrow with a red badge showing 1"), polluting the recorded element descriptions.

This PR replaces the numbered callout with a badge-neutral centered marker: a hollow ring with four crosshair ticks, no digit, no leader line, no offset. The prompt wording is aligned with the new marker.


How I found it



1. I was using Midscene Studio (Xiaomi device, adb + scrcpy, 1080×2400 screenshots) to record taps in a finance app.
2. After every tap, the recorder auto-generates an element description via the point-description path (describeElementAtPoint → service.describe → compositePointMarkerImg). The generated descriptions repeatedly mentioned a red badge that did not exist in the app. Examples from ai-call.log (back-translated):
   • "the back arrow icon in the top-left corner with a red badge showing the number 1"
   • "the fund group item … with a red unread-count badge (1) in the top-right corner"
3. This reproduced consistently with both models I tested — qwen3-vl-plus and qwen3.7-plus — so it did not look like a model-specific quirk.
4. I inspected the request payloads in the logs, then regenerated the exact image sent to the model by running the production compositePointMarkerImg code on a real 1080×2400 recording screenshot. The marker turned out to be a red filled circle with a bold white "1", drawn offset from the tap point with a leader line — structurally the same shape as an Android notification badge.
   

Root cause


drawPointMarker in packages/shared rendered the point marker as a numbered callout bubble (filled red circle + white digit + leader line, offset from the point). Even though the system prompt states the annotation is temporary, the badge-like appearance was strong enough that both models interpreted it as a genuine notification indicator and included it in the element description.


Before / after


Same real recording screenshot, same tap point — generated with the production code path (marker code from main on the left, this PR on the right):


The old marker is a red filled bubble with a white "1" connected by a leader line; the new marker is a hollow centered ring with crosshair ticks. The white halo ring and white ticks stay visible on dark/red backgrounds, while the red ring stays visible on light backgrounds, and the center is left untouched so the tapped element remains readable.


Changes


packages/shared/src/img/box-select.ts

• Rewrote drawPointMarker to draw a hollow marker centered exactly on the tap point: white halo ring + colored ring + four white crosshair ticks — no digit, no leader line, no callout offset. The center pixels are never painted. Red/blue marker variants (indexId) are preserved.
• Removed the now-unused drawCallout / drawEllipse helpers (dead code, no remaining callers).
  
  packages/core/src/ai-model/prompt/describe.ts
• System prompt now refers to "the temporary target marker (a ring with a crosshair)" and "marker center" instead of "callout" / "callout endpoint/center".
• The overlay ignore list explicitly covers ring, crosshair, line, color, marker, border, dot, or selection box.
  
  packages/core/src/service/index.ts
• User-facing image messages updated from "temporary callout" to "temporary target marker" wording (both the single-image path and the deep-describe multi-image path).
  
  Tests
• packages/shared/tests/unit-test/image/index.test.ts: pixel assertions updated for the centered ring (ring pixels at the expected offsets are colored; point-center pixels stay untouched; pixels outside the marker are untouched).
• packages/core/tests/unit-test/prompt/describe.test.ts (+ snapshot) and service-describe.test.ts: assertions updated to the new marker wording.
  

Validation



• npx rstest run tests/unit-test/image in packages/shared — 76/76 passed
• npx rstest run tests/unit-test/prompt/describe.test.ts tests/unit-test/service-describe.test.ts in packages/core — 23/23 passed
• npx nx build shared and npx nx build core — success
• Biome lint on all changed files — no findings
• Regenerated the exact image payload the model receives from a real Android recording screenshot via production code, confirming the new marker contains no badge-like or digit glyph (see before/after image above)
  
  No public API changes. The point marker is only used by the describe-for-point path; report rendering, planning, and element-index boxed annotations are untouched.