[Fix] Multi-root workspaces treat secondary roots as outside the workspace

[roomote]

Opened on behalf of Elliott de Launay. View the task or mention @roomote for follow-up asks.

Closes #204

What problem this solves

Fixes an issue where users working in a VS Code multi-root workspace could have tools treat files in secondary roots as outside the workspace. Read, edit, patch, and create flows could resolve relative paths against the first root, and root-specific .rooignore rules were not applied consistently.

Why this change was made

This change makes path resolution choose the workspace root that already contains the target file or its parent directory, then carries that resolved path through ignore and protection checks, file-context tracking, and file-tool operations. It also fixes the Windows absolute-path command case so secondary-root .rooignore rules still apply when commands reference C:\... paths directly, and adds focused unit coverage for the new multi-root resolver and absolute diff-path behavior.

User impact

File tools now behave correctly across multi-root workspaces, including creating new files under the right root and honoring secondary-root .rooignore rules across Unix and Windows command styles.

Related PRs

• #228 - follow-up VS Code e2e coverage and harness split

[roomote]

2 issues outstanding. See task

• resolvePathInWorkspace() now resolves brand-new files into the only workspace root that already contains the parent directory, so create flows no longer fall back to the first root in that case.
• Secondary-root .rooignore content is now loaded for execute_command and the prompt instructions instead of staying pinned to this.cwd.
• e2e-mock is still red on the current head: the multi-root repro times out after 60s, so CI still is not proving that the second workspace folder becomes available under GitHub Actions. — moved to sibling PR #228 after splitting the product fix from the VS Code e2e harness work.
• validateCommand() no longer skips Windows absolute paths, so validateAccess() still runs for secondary-root C:\\... arguments.
• src/core/tools/__tests__/writeToFileTool.spec.ts now uses an explicit platform-aware in-root diff-path expectation, which matches the remaining Windows failure on f455a8e73 instead of feeding the assertion back through mocked path.resolve.
• src/core/tools/__tests__/applyPatchTool.execute.spec.ts now matches the actual diff-path behavior on Windows instead of assuming the Linux-only in-root path shape.
• src/core/tools/__tests__/listFilesTool.spec.ts, src/core/tools/__tests__/searchFilesTool.spec.ts, and src/core/tools/__tests__/applyDiffTool.spec.ts now directly cover the remaining multi-root path-resolution surfaces that were still missing from the patch.
• platform-unit-test (ubuntu-latest) is still running on d4df00b6edcffd63cb03272eed48d2c05c36c3fb after the bounded wait, so the branch is not clean on Ubuntu yet.
• platform-unit-test (windows-latest) is still running on d4df00b6edcffd63cb03272eed48d2c05c36c3fb after the bounded wait, so the branch is not clean on Windows yet.

[roomote]

Pushed d4df00b6e on #225.

What changed:

• fixed the remaining Windows-only expectation mismatch in writeToFileTool.spec.ts by making the in-root diff-path expectation explicit per platform instead of routing it back through the mocked path.resolve
• kept the patch scoped to the one spec file that still matched the old f455a8e73 failure log

Validation:

• pnpm --dir src exec vitest run core/tools/__tests__/writeToFileTool.spec.ts
• pnpm --dir src exec vitest run core/tools/__tests__/writeToFileTool.spec.ts core/tools/__tests__/applyPatchTool.execute.spec.ts core/tools/__tests__/listFilesTool.spec.ts core/tools/__tests__/searchFilesTool.spec.ts core/tools/__tests__/applyDiffTool.spec.ts
• pnpm --dir apps/web-roo-code test

Visual proof: not applicable for this change because it only updates backend/tooling test coverage.

CI is rerunning now on d4df00b6e. On the previous head f455a8e73, codecov/patch was already green; this push is specifically to clear the remaining platform-unit-test (windows-latest) failure.

[codecov]

Codecov Report

❌ Patch coverage is 80.39773% with 69 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/core/tools/ReadFileTool.ts	26.92%	19 Missing ⚠️
src/utils/pathUtils.ts	89.76%	13 Missing ⚠️
src/core/ignore/RooIgnoreController.ts	90.80%	6 Missing and 2 partials ⚠️
src/core/tools/ApplyPatchTool.ts	82.85%	6 Missing ⚠️
src/core/context-tracking/FileContextTracker.ts	28.57%	5 Missing ⚠️
src/core/tools/WriteToFileTool.ts	66.66%	4 Missing and 1 partial ⚠️
src/core/tools/ApplyDiffTool.ts	60.00%	3 Missing and 1 partial ⚠️
src/core/tools/EditTool.ts	80.00%	2 Missing ⚠️
src/core/tools/ListFilesTool.ts	60.00%	2 Missing ⚠️
src/core/tools/SearchFilesTool.ts	60.00%	2 Missing ⚠️
... and 2 more

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