fix: keep unstretched selection line ends natural

[dergigi]

Fixes #266 by keeping reader selection cursors anchored to the natural text end when a justified line has no stretchable spaces. This avoids displaced selection handles on mixed CJK plus inline URL lines that do not actually receive inter-word justification.

• keeps inter-word justification accounting limited to real spaces
• prevents line-end cursors from jumping to the full paragraph width when nothing was stretched
• adds regression coverage for unstretched justified line ends and CJK plus inline URL spacing

Checks:

• git diff --check
• Local Gradle/JVM tests blocked because Java/JAVA_HOME is missing on this host

Summary by CodeRabbit

• Bug Fixes

  • Corrected cursor positioning at the end of justified lines without expandable spaces.
  • Justified text now distributes extra spacing across spaces only; inter-character CJK gaps are no longer expanded.

• Tests

  • Added coverage for natural line-end positioning and space-only justification behavior.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 354a16b4-41e8-4030-91fb-24ea49307b80

📥 Commits

Reviewing files that changed from the base of the PR and between 3a393bb and 22fca72.

📒 Files selected for processing (2)

• app/src/main/java/org/dergigi/boris/ui/reader/JustifiedLayout.kt
• app/src/test/java/org/dergigi/boris/ui/reader/JustifiedLayoutTest.kt

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📝 Walkthrough

Walkthrough

JustifiedLayout now counts spaces only for justification. Line ends with no stretch units keep their natural position. Tests cover the updated cursor positioning and CJK behavior.

Changes

Justified layout

Layer / File(s)	Summary
Stretch-unit positioning app/src/main/java/org/dergigi/boris/ui/reader/JustifiedLayout.kt	visualCursor reuses the full-line stretch-unit count. visualX returns the natural position when no stretch units exist. stretchUnitCount counts spaces only, so adjacent CJK characters do not create stretch units.
Stretch-unit validation app/src/test/java/org/dergigi/boris/ui/reader/JustifiedLayoutTest.kt	Tests use the renamed stretch-unit parameters. Tests cover natural line ends, space-only counting, and the removal of CJK-gap justification.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~15 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 22fca

The selection-positioning correction is covered by focused regression tests, with no remaining concrete merge-blocking risk identified.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	For #266, the reviewed head does not count CJK, Kana, or Hangul inter-character gaps as stretch units. stretchUnitCount increments only for ASCII spaces. The regression test `stretchUnitsCountSpaces…	Restore stretch-unit detection for the required CJK, Kana, and Hangul inter-character gaps. Keep the pointer mapping and selection rendering calculations based on those units. Add regression tests for mixed CJK text with an inline URL and f…
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 11 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Out of Scope Changes check	✅ Passed	The changes remain limited to justified-layout cursor mapping and its regression tests in JustifiedLayout.kt and JustifiedLayoutTest.kt. The line-end behavior and stretch-unit tests support the li…
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main implemented fix: keeping selection line ends at their natural positions when no justification stretch applies.

Full details: Linked Issues check

Explanation

For #266, the reviewed head does not count CJK, Kana, or Hangul inter-character gaps as stretch units. stretchUnitCount increments only for ASCII spaces. The regression test stretchUnitsCountSpacesOnly() asserts zero units for adjacent CJK text and a URL. Therefore visualCursor, highlightRects, and offsetAt do not apply the required justification mapping to the affected mixed-script lines. The line-end natural-position fix does not satisfy the CJK anchor requirement.

Resolution

Restore stretch-unit detection for the required CJK, Kana, and Hangul inter-character gaps. Keep the pointer mapping and selection rendering calculations based on those units. Add regression tests for mixed CJK text with an inline URL and for the required scripts.

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Commit to this branch
• Create a new PR

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

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Inline comments:
In `@app/src/main/java/org/dergigi/boris/ui/reader/JustifiedLayout.kt`:
- Line 56: Update stretchUnitCount in JustifiedLayout so it counts only
inter-word spaces and no longer includes isCjkJustificationGap boundaries. Keep
the existing full-line and prefix calculations unchanged, without adding special
prefix-boundary handling.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: f2ad0aee-63f8-4f3b-b034-58b5961ef80f

📥 Commits

Reviewing files that changed from the base of the PR and between 81ed01b and 3a393bb.

📒 Files selected for processing (2)

• app/src/main/java/org/dergigi/boris/ui/reader/JustifiedLayout.kt
• app/src/test/java/org/dergigi/boris/ui/reader/JustifiedLayoutTest.kt

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.