fix(read_file): VSCode decoding for native tool reads

[hannesrudolph]

Fixes non-UTF8 file decoding for native tool-calling reads by preferring VSCode’s document decoding (and falling back to the existing byte-based readers).

Closes #3555

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Test Files 2 passed (2)
Tests 73 passed (73)
Start at 08:28:19
Duration 759ms (transform 262ms, setup 82ms, collect 458ms, tests 189ms, environment 0ms, prepare 62ms)

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Important

Enhance ReadFileTool to use VSCode's document decoding for non-UTF8 files and add readTextWithTokenBudget() utility.

• Behavior:
  • ReadFileTool in ReadFileTool.ts now uses VSCode's document decoding for non-UTF8 files, falling back to byte-based readers if unavailable.
  • Introduces tryReadTextViaVscode() and sliceTextLines() functions for handling text reading and slicing.
  • Limits VSCode text reads to files under 2MB.
• Utilities:
  • Adds readTextWithTokenBudget() in read-text-with-budget.ts for reading text with a token budget, mirroring readFileWithTokenBudget().
• Tests:
  • Updates readFileTool.spec.ts to mock VSCode and test new VSCode decoding path.
  • Adds tests for readTextWithTokenBudget() behavior.

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[roomote]

Oroocle   See task on Roo Cloud

Review completed. I left 1 inline suggestion to keep native VSCode-decoded reads consistent with the existing out-of-range <line_range> behavior.

• Native VSCode-decoding path: handle out-of-range <line_range> the same way as readLines() (RangeError) rather than returning an empty slice.

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}

[roomote]

When native reads use VSCode-decoded text, out-of-range <line_range> values no longer error (for example range.start beyond the file length). readLines() rejects in that case, but sliceTextLines() returns an empty string and addLineNumbers() can emit a misleading blank line like 1000 | .

Suggested change

	const rawRangeText =
	useNative && maybeText !== undefined
	? sliceTextLines(maybeText, range.start - 1, range.end - 1)
	: await readLines(fullPath, range.end - 1, range.start - 1)
	if (useNative && maybeText !== undefined && range.start > totalLines) {
	throw new RangeError("Line with index ${range.start - 1} does not exist in \"${fullPath}\". Note that line indexing is zero-based")
	}
	const rawRangeText =
	useNative && maybeText !== undefined
	? sliceTextLines(maybeText, range.start - 1, range.end - 1)
	: await readLines(fullPath, range.end - 1, range.start - 1)

_{Fix it with Roo Code or mention @roomote and request a fix.}