Investigate confirmed Android LINE ID duplicate input (#200)

[limeimetw]

Summary

• Adds the privacy-preserving investigation record for Android：LINE 新增好友 ID 搜尋欄重複輸入字元 #200.
• Tracks fix#200 Android in the public backlog.
• Separates verified report details, source findings, hypotheses, and unresolved runtime evidence.

Verified

• The reported path is LINE → Add Friends → ID search on Android 14.
• One reported j tap displays jj.
• A maintainer independently reproduced the Android：LINE 新增好友 ID 搜尋欄重複輸入字元 #200 behavior on a physical Samsung phone, confirming the Android defect is not limited to the reporter's ASUS device.
• The reporter supplied Android 14 ASUS_AI2202, LIME 6.1.36, and LINE 26.11.0; the defect reproduces from the Chinese keyboard but not from LIME's English keyboard.
• The current direct English software-key path contains one InputConnection.commitText() call per handleCharacter() invocation.

Unresolved blocker

The user-visible defect is confirmed on a physical Samsung phone, but the exact runtime boundary is still unknown. The reporter also recalls the same symptom in another unidentified app or input context; this keeps common Android editor conditions in scope but is not a second reproducible environment. The Samsung model/Android version, EditorInfo flags, key-dispatch count, and InputConnection call count have not yet been recorded. No production source fix is proposed until runtime evidence isolates the duplicate boundary.

Next verification

1. Preserve the confirmed Samsung reproduction and record its model/Android version when available.
2. Capture privacy-safe field flags and dispatch/commit counts on the reproduced path without logging the entered LINE ID.
3. Add a RED regression through the proven failing path.
4. Implement the smallest root-cause correction and verify both Chinese/English keyboard paths plus ordinary, password, email, and URL/search fields.

Checks

• git diff --check
• Manual source and documentation review
• Claude Code Opus read-only reviews, including the follow-up scope/privacy review, completed with no blocking findings.

Related: #200