Fix counting extra lines when lines wrap

[mogzol]

(note: this PR was originally submitted as #165, but I needed to change the source branch, so I am re-creating it)

Fixes #164

Previously, extra lines were counted only by the number of line breaks in them, so the number of lines cleared would be incorrect if any lines wrapped. Additionally, prevLineCount could be wrong if the size of the terminal changes between renders.

To fix this, the number of lines to clear is calculated immediately before clearing them, and the 'string-width' library is used to determine accurate widths and line counts. This is the same library used by 'wrap-ansi', so it should be reliable, and it is not actually a new dependency.

Summary by CodeRabbit

• Refactor
  • Reworked terminal log rendering to track previously rendered output more precisely, improving behavior across updates and terminal resizing.
• Bug Fixes
  • Fixed occasional line misalignment or incorrect clearing/erasing when output contains wide characters (e.g., full-width text) or when the terminal dimensions change.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: c78fbdcb-f6c9-4f21-8302-b20634c17231

📥 Commits

Reviewing files that changed from the base of the PR and between 4a335b0 and 4f7d1de.

⛔ Files ignored due to path filters (1)

• pnpm-lock.yaml is excluded by !**/pnpm-lock.yaml

📒 Files selected for processing (2)

• package.json
• src/utils/log-update.ts

🚧 Files skipped from review as they are similar to previous changes (2)

• package.json
• src/utils/log-update.ts

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📝 Walkthrough

Walkthrough

Adds string-width as a direct dependency and rewrites LogUpdate's internal line-tracking: prevLineCount (a number) is replaced by prevLines (a stored string), and a lineCount getter now computes the true number of terminal rows occupied by computing character widths with stringWidth against the current terminal column count.

Changes

LogUpdate line-wrap fix

Layer / File(s)	Summary
Dependency, state shape, and lineCount computation package.json, src/utils/log-update.ts	Adds string-width to dependencies, imports stringWidth, replaces the prevLineCount: number field with prevLines: string | null, updates render() to store the rendered string into prevLines, and rewrites the lineCount getter to split prevLines on \n and sum wrapped-line counts using stringWidth vs. current columns.
clear, done, and _onData using computed lineCount src/utils/log-update.ts	clear() erases using this.lineCount (now string-width-aware), done() resets prevLines to null, and _onData appends intercepted output into prevLines instead of incrementing a numeric counter.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐇 A long line once wrapped round the bend,
And the bar would just duplicate—no end!
Now I measure each glyph, count the rows,
Clearing just what the terminal shows.
No more ghost bars haunting the screen! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Fix counting extra lines when lines wrap' directly summarizes the main change: fixing how extra lines are counted when terminal lines wrap, which is the core issue addressed in the PR.
Linked Issues check	✅ Passed	The PR satisfies issue #164 by adding string-width dependency and refactoring log-update.ts to accurately count wrapped lines using character width calculations instead of newline counting.
Out of Scope Changes check	✅ Passed	All changes directly address the line wrapping issue: adding string-width dependency and refactoring LogUpdate to use it for accurate line counting.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/utils/log-update.ts`:
- Around line 72-75: The clear() method calls this.done() before erasing lines,
but this.done() sets this.prevLines to null, causing the lineCount getter to
return 0 and eraseLines(0) to produce an empty string. Fix this by reordering
the operations in the clear() method: call
this.write(eraseLines(this.lineCount)) before this.done() so that lineCount is
computed while prevLines is still set, ensuring lines are actually erased before
the state is reset.
- Around line 84-91: In the _onData method, the prevLines property is typed as
string | null and initialized as null, but at line 88 where this.prevLines +=
data is executed, if prevLines is still null, the += operator will concatenate
the string "null" to the data, corrupting the buffer. Add a guard to check if
prevLines is null before performing the concatenation—either initialize it to an
empty string if null, or use conditional logic to ensure the assignment only
happens when prevLines is a valid string.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 5242c2be-df6b-4c45-9fab-e8a98633d439

📥 Commits

Reviewing files that changed from the base of the PR and between c7d3c81 and 0f1cb60.

⛔ Files ignored due to path filters (1)

• pnpm-lock.yaml is excluded by !**/pnpm-lock.yaml

📒 Files selected for processing (2)

• package.json
• src/utils/log-update.ts