Fix JSDoc comment formatting with tab indentation

[Copilot]

Problem

When formatting TypeScript/JavaScript files with tab indentation (ConvertTabsToSpaces: false), the formatter incorrectly placed spaces before tabs in JSDoc comment lines, resulting in malformed indentation.

For example, formatting this code:

class Foo {
	/**
	 * @param {string} argument - This is a param description.
	 */
	example(argument) {
		console.log(argument);
	}
}

Would produce incorrect output with spaces before tabs:

class Foo {
	/**
 	* @param {string} argument - This is a param description.
 	*/
	example(argument) {
		console.log(argument);
	}
}

Notice how the comment lines now have the pattern space tab * instead of the correct tab space *.

Root Cause

The bug was in the getIndentationString function in internal/format/span.go. When generating indentation with tabs, the function was concatenating spaces before tabs instead of tabs before spaces:

// WRONG:
res = strings.Repeat(" ", spaces) + res  // spaces + tabs

This was opposite to the TypeScript reference implementation in src/services/formatting/formatting.ts:

return spaces ? tabString + repeatString(" ", spaces) : tabString;  // tabs + spaces

Solution

Fixed the concatenation order to match the TypeScript implementation:

// CORRECT:
res = res + strings.Repeat(" ", spaces)  // tabs + spaces

This ensures that tabs always come before spaces in indentation strings, which is the standard convention and matches editor expectations.

Testing

Added a comprehensive test case format JSDoc with tab indentation that validates:

• Comment lines have the pattern \t * (tab, space, asterisk)
• The incorrect pattern \t* (space, tab, asterisk) is not present
• Other code indentation remains correct

All existing tests continue to pass, confirming no regressions.

Fixes the issue described in the problem statement where JSDoc comments with tab indentation were being incorrectly formatted.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Incorrect formatting of JSDoc comment with tab indentation</issue_title>
<issue_description>For a file that uses tab indentation, try running format:

class Foo {
	/**
	 * @param {string} argument - This is a param description.
	 */
	example(argument) {
console.log(argument);
	}
}

Bug
This incorrectly moves the spaces to the start of the doc comment lines so you end up with space tab *.

class Foo {
	/**
 	* @param {string} argument - This is a param description.
 	*/
	example(argument) {
		console.log(argument);
	}
}
```</issue_description>

<agent_instructions>Make a formatting test first, and make sure you look at the original formatting code in the submodule.</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

Fixes #1899

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[Copilot]

Pull Request Overview

This PR fixes a bug in the TypeScript formatter where JSDoc comments with tab indentation were incorrectly formatted, placing spaces before tabs instead of tabs before spaces.

Key changes:

• Fixed concatenation order in getIndentationString function to place tabs before spaces
• Added comprehensive test case to validate JSDoc formatting with tab indentation
• Ensured alignment with TypeScript reference implementation behavior

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
internal/format/span.go	Fixed concatenation order in getIndentationString to place tabs before spaces
internal/format/comment_test.go	Added test case to verify JSDoc formatting with tab indentation works correctly