[codex] Preserve desktop user-data probe failures

[juliusmarminge]

Summary

• stop treating every legacy user-data path probe failure as path absence
• add a Schema-backed error carrying the inspected path and exact filesystem cause
• keep genuine path absence as the existing false result and cover permission failure with one focused test
• export the existing service make value to match module conventions

Verification

• vp test apps/desktop/src/app/DesktopAppIdentity.test.ts
• vp check (passes with 20 pre-existing warnings)
• vp run typecheck

Open PR overlap audit

Audited every open PR with gh pr list --limit 1000 and paginated per-PR files, checking both filename and previous_filename. The test file is also touched by unrelated feature/fix PRs #2901, #2916, #2925, and #2679; the source file has no open-PR overlap.

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Note

Medium Risk
Changes early startup path selection in DesktopApp; mis-handled errors could block launch, but the new behavior avoids silently using the wrong user-data directory on probe failures.

Overview
Legacy user-data path resolution no longer swallows filesystem errors from exists on the alpha directory. Probe failures now surface as DesktopUserDataPathResolutionError (path + underlying cause) instead of being treated like “path missing” and falling through to the new user-data dir.

resolveUserDataPath is typed to fail with that error; make is exported for module conventions. Tests simulate permission-denied probes and assert the error shape and message.

^{Reviewed by Cursor Bugbot for commit da565b0. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Preserve FileSystem.exists probe failures in DesktopAppIdentity.resolveUserDataPath

• Introduces DesktopUserDataPathResolutionError to surface failures when probing the legacy desktop user-data path via FileSystem.exists.
• Previously, any error from FileSystem.exists was swallowed and treated as "path does not exist", silently returning the non-legacy path. Now the error is mapped and propagated.
• resolveUserDataPath in the DesktopAppIdentity service interface now has a typed failure channel of DesktopUserDataPathResolutionError instead of being infallible.
• Behavioral Change: callers of resolveUserDataPath must now handle the new failure case; code that previously always received a success value may now receive an error.

^{Macroscope summarized da565b0.}

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[macroscopeapp]

Approvability

Verdict: Approved

Self-contained error handling improvement that preserves file system errors instead of silently swallowing them. The change includes test coverage and is made by the original author of the file.

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