fix(mobile): keep the Android composer placeholder on one line

[SunkenInTime]

On Android the composer placeholder wraps to a second, clipped line on phones with a wide system font or a larger font scale (Samsung defaults), so the resting composer shows "Ask the repo agent, or run a / command" with the second line cut off. It never showed on a stock Pixel or the emulator at default settings, which is why it slipped through.

An editable TextView never applies ellipsize to its hint, so the hint wrapped whenever it ran out of width. The native editor now cuts the placeholder to one line with an ellipsis for whatever width it is measured at, and recomputes it when the width, font size, or font family changes. The expanded composer still shows the full text when it fits.

Reproduced on a Pixel 8 emulator at font scale 1.3 (Settings > Display > Font size).

Before / after (composer)

Before / after (full screen)

Tests: :t3-composer-editor:testDebugUnitTest (three new Robolectric cases for the placeholder, existing paste tests still green).

Claude Fable 5.1 via Claude Code in T3 Code.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Composer editor placeholders now truncate with an ellipsis when they exceed the available width.
  • Placeholders automatically update when the editor is resized or its font size changes.
  • Expanding the editor restores the full placeholder text.

• Tests

  • Added coverage for narrow, wide, and resized editor placeholder behavior.

[macroscopeapp]

Approvability

Verdict: Approved at 7222a22

Macroscope's review found this PR approvable — This is a narrowly scoped Android UI bug fix that ellipsizes the existing composer placeholder and adds focused Robolectric coverage for resizing behavior. It does not alter product defaults, APIs, security-sensitive code, deployment, or static-analysis configuration.

^{You can add or adjust custom eligibility rules. Learn more.}

[coderabbitai]

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ℹ️ Recent review info

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Run ID: 75a58ac9-ae9f-4eea-b6ac-bb48236fea26

📥 Commits

Reviewing files that changed from the base of the PR and between dfbb11b and 7222a22.

📒 Files selected for processing (2)

• apps/mobile/modules/t3-composer-editor/android/src/main/java/expo/modules/t3composereditor/T3ComposerEditorView.kt
• apps/mobile/modules/t3-composer-editor/android/src/test/java/expo/modules/t3composereditor/ComposerPlaceholderTest.kt

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📝 Walkthrough

Walkthrough

The Android composer now ellipsizes placeholder text to one line based on available width. It reapplies the placeholder after measurement and font-size changes. Robolectric tests cover narrow, wide, and resized editors.

Changes

Composer placeholder behavior

Layer / File(s)	Summary
Width-aware placeholder rendering apps/mobile/modules/t3-composer-editor/android/src/main/java/expo/modules/t3composereditor/T3ComposerEditorView.kt	The editor stores the placeholder separately, applies end ellipsization within the available width, and reapplies it during measurement and font-size updates.
Placeholder resizing tests apps/mobile/modules/t3-composer-editor/android/src/test/java/expo/modules/t3composereditor/ComposerPlaceholderTest.kt	Robolectric tests verify truncation at narrow widths, full text at wide widths, and restoration after widening the editor.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: chrisdeeming

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 13 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the main change: keeping the Android composer placeholder on one line.
Description check	✅ Passed	The description explains what changed, why the fix is needed, the UI impact, screenshots, and test coverage. It does not include the template's Checklist section, but the required information is other…

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