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Limrun Android: `fill` inserts at the cursor instead of replacing the field's text

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@thymikee is already working on this.

Since Oct 10, 2026.

  • #3362 by @thymikee — open

Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
62/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
android, typescript
Domain
mobile

Research direction

Start in the Android fill path where agent-device returns after the provider-native provider.text call, since that call skips the adb clear, verify and retry steps (KEYCODE_MOVE_END and KEYCODE_DEL). The Limrun instance client's setText and pressKey calls are the relevant entry points. Done means fill on a field with existing text leaves exactly the new value, and a mismatch is reported rather than passing silently. Reproduce with the Settings search field commands in the issue.

Written by the indexing model from the issue text.

Description

Summary

On a Limrun Android instance, fill does not replace the existing contents of a text field. The new text is inserted wherever the tap leaves the cursor, so filling a field that already has a value produces a concatenation of the old and new text. The help text says fill <target> <text> replaces, and that is what happens on local emulators.

Environment

  • agent-device: 0.21.15, and the same code path is present in 0.21.24 (latest at the time of writing)
  • Provider: Limrun, Android instance (agent-device connect limrun --platform android)
  • Keyboard on the instance: com.android.inputmethod.latin (the agent-device test IME is not active)
  • App: the system Settings app (any EditText reproduces it)

Steps to reproduce

agent-device connect limrun --platform android --run-id fill-repro --session repro
agent-device open settings --platform android --session repro
agent-device snapshot -i --platform android --session repro   # find "Search Settings"
agent-device click @e2 --platform android --session repro      # opens the search field
agent-device fill @e7 "[email protected]" --platform android --session repro
agent-device fill @e7 "[email protected]" --platform android --session repro
agent-device snapshot -i --platform android --session repro

Expected

After the second fill, the field contains:

[email protected]

Actual

The second fill taps the field center, which puts the cursor inside the existing value, and inserts the text there:

[email protected][email protected]

Both fill calls exit successfully. A caller that does not re-read the field carries on with the wrong value.

Cause

On Android, fill first checks whether the device provider supplies its own text entry. Limrun does (provider.text → the Limrun instance client's setText({ x, y }, text)), so agent-device returns after that call. It never reaches the Android path that clears the field (KEYCODE_MOVE_END + KEYCODE_DEL), verifies the result and retries, or uses the test IME.

Calling the Limrun Android instance client directly on the same instance shows that setText never replaces:

Call Result
setText({ x, y }, text) (what agent-device sends) inserted at the cursor
setText({ selector: { focused: true } }, text) inserted at the cursor
setText(undefined, text) inserted at the cursor
setText({ selector: { focused: true } }, '') rejected: text is required

So with the provider-native path there is currently no way to clear the field before typing.

Workaround that worked

Selecting all and deleting with hardware key events before setText, through the same Limrun instance client:

await client.pressKey('a', ['ctrl']);
await client.pressKey('del');
await client.setText(undefined, text);

This left the field holding exactly the requested text in 3 of 3 runs. The select and delete took about 350 ms together; setText took about 1 s.

Suggested fix

For a Limrun Android fill, clear the focused field before the provider-native setText (for example with the Ctrl+A / Delete key events above), then run the existing verification so a mismatch is reported instead of passing silently. Alternatively, route Limrun Android fill through the existing adb clear/verify/retry path or the test IME.

Possibly related (not reproduced)

In one run, a fill into a field that had just taken focus from another field lost its first character (jane… arrived as ane…). I could not reproduce it on a single field in 4 attempts, so it is mentioned only in case it shares the cause.

Dominant language
TypeScript
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Forks
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Avg merge
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Merged PRs (30d)
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