refactor(vscode): share context mention parsing and attachments

[marius-kilocode]

What Problem This Solves

Git and terminal context mentions duplicate the same standalone-boundary/span parsing and UTF-8 text attachment construction. Maintaining the copies separately risks differences in matching or source metadata.

Why This Change Was Made

Extract only these two algorithms into a browser-safe helper, retaining the feature-specific named wrappers, token constants, filenames, and patterns. Keep the already-shared request lifecycle untouched. This is a small semantic duplicate below the scanner threshold, not a new mention framework.

User Impact

No intended behavior change. Both mentions retain their boundaries, first-match spans, repeated-call behavior, source metadata, and exact encoded content. Git retains its 15-second timeout, repository gate, scope/default context, and disposal reset. Terminal retains its 10-second timeout, embedded-output fallback, empty-content rejection, and distinct disposal behavior.

Evidence

• Five focused files, +69/-72 lines: net -3 total LOC and -7 production LOC, including the new helper and imports.
• Duplication reports before and after: 21 pairs, 404 duplicated lines, 2,758 duplicated tokens. No scanner settings, suppression, or allowlist changes.
• Extension typecheck, lint, knip, compile, bundle, formatting, package guard, and 113 focused tests passed. Typecheck, lint, knip, bundle, and the focused tests were rerun after fast-forwarding to current main.
• Isolated VS Code submission with both @git-changes and @terminal produced git-changes.txt and terminal-output.txt. Verified exact data URLs against real Git and terminal context responses, source ranges, and fixture text containing non-ASCII characters and reserved URL characters. The disposable profile and fixture were removed.
• Model generation was intentionally unavailable through a local-only test provider; this checked attachment creation and submission, not a model response.

Manual check: modify a Git file, print terminal output, submit Inspect @git-changes and @terminal, and inspect both attachments.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (5 files)

• packages/kilo-vscode/webview-ui/src/hooks/context-mention-utils.ts
• packages/kilo-vscode/webview-ui/src/hooks/git-changes-context-utils.ts
• packages/kilo-vscode/webview-ui/src/hooks/terminal-context-utils.ts
• packages/kilo-vscode/tests/unit/terminal-context-utils.test.ts
• packages/kilo-vscode/tests/unit/terminal-architecture.test.ts

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_{Reviewed by grok-4.6 · Input: 98.8K · Output: 7.1K · Cached: 175.4K}

_{Review guidance: REVIEW.md from base branch main}