[Qiyuanqiii]

Description

internal/privatefile and internal/workspaceidentity are two packages without a single test file, and both sit on a security boundary:

• internal/workspaceidentity provides PathPolicy, which decides which paths an Agent may not read or write, and Fingerprint, which binds a workspace root to a platform file identity (dev/ino, or volume serial number plus file index).
• internal/privatefile performs the atomic write and the cross-process lock behind the OAuth credential files, and is imported directly by internal/chatgptauth and internal/mcpoauth.

internal/privatefile/file.go already reserves an injection point for tests:

// rename may be nil to use os.Rename; callers may inject it to test an interrupted commit.

No test in the repository used it, so the interrupted-commit failure path was never verified.

This PR adds tests only. No production code changes, no runtime behavior changes.

Test design

Follows the existing repository conventions. Internal test packages (package privatefile / package workspaceidentity), stable error-code assertions (apperror.CodeOf(err) != apperror.CodeInvalidArgument, matching internal/application/agent_code_project_config_test.go), no new dependencies, no new test framework, and no contact with internal/llm or any API contract.

Covers the refusal paths, not the happy path. The value of a security boundary lives in its rejection branches. PathPolicy covers absolute paths, .. escapes, unnormalized paths, control characters, invalid UTF-8, malformed globs, and an invalid policy itself; privatefile covers an injected interrupted commit (the original file content stays unchanged and the temporary file is cleaned up), a missing parent directory, an already-cancelled context, a context that times out while waiting for the lock, and mutual exclusion between concurrent holders.

Locks the current contract instead of making a semantic decision for maintainers. MatchPath("a/**", "a") currently returns true, that is, ** also matches zero path segments. The existing test (agent_code_project_config_test.go uses ExcludePaths: ["secrets/**"]) passes under both semantics, so the intent cannot be inferred. This PR asserts the current implementation behavior and states the reason in a code comment: ** covering zero segments keeps the decision for Check("a") consistent with Check("a/b/c"), avoiding a split where the directory is visible but its contents are hidden. If maintainers think at least one segment should be required, that is a separate behavior change and belongs in its own issue, not in a test PR.

Platform portability. The 0600 permission assertion is skipped on Windows, where Chmod only affects the read-only bit. The symlink case skips itself with t.Skipf where symlinks cannot be created, so it never passes silently. The process-lock case relies on mutual exclusion between different handles, which Linux flock and Windows LockFileEx both provide.

21 test functions were added, including three table-driven groups that cover 37 further cases.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring (no functional changes)
• Documentation update
• CI / Build / Tooling

This is a test-only addition: no production file changes, and the classified check is backend only.

Surface governance

• No Surface is added, promoted, downgraded, deprecated, or removed.

N/A — no Surface change. No registry entry, generated inventory, or documentation contract is touched, because the change only adds test files and alters no public contract.

Validation

Current revision: b0a3eef5, synchronized with main through b58f8981.

Check	Result	Revision
gofmt -l internal/privatefile internal/workspaceidentity	No output	b0a3eef5
go vet ./internal/privatefile/... ./internal/workspaceidentity/...	Passed	b0a3eef5
go test -count=1 ./internal/privatefile/... ./internal/workspaceidentity/...	Passed: privatefile 0.623s, workspaceidentity 0.450s	b0a3eef5
go test -race -count=1 ./internal/privatefile/... ./internal/workspaceidentity/...	Passed: privatefile 1.525s, workspaceidentity 1.357s	b0a3eef5
Downstream regression, ./internal/codeintel/... ./internal/credential/...	Passed: codeintel 7.616s, credential 0.234s	b0a3eef5
go build ./...	Passed	b0a3eef5
go test -count=1 ./... (full repository)	The run was stopped after internal/app, because the heavy internal/application and internal/store packages exceed the local session budget on this Windows host. The only failure observed, internal/app TestRunCommandExecuteIsConfirmedAuditedAndExactlyOnce (controlled command execution platform is unavailable: approved executable is unavailable), reproduces identically on the untouched base b58f8981 in a separate worktree, so it is a limitation of this host and not a regression from this PR.	b0a3eef5
Coverage of the two changed packages	privatefile 83.3%, workspaceidentity 91.7%; both packages had no test file at all before, so they carried no coverage	b0a3eef5
scripts/ci/classify_changes.py, base b58f8981	Selected checks: backend; full, store, web, journeys, lsp, rust, native, ui, race, audit, and packaging are all false	b0a3eef5
Symlink subtest isolation	TestFingerprintRefusesFilesSymlinksAndMissingRoots now runs regular file, missing root, and symlinked root as separate subtests, so a host without symlink support skips only the symlink case	b0a3eef5
CI Select affected checks and Go checks	Passed on Linux, run 40882124390: go vet and go test for both changed packages, plus internal/releasegate and internal/producte2e; every other gate was skipped by classification	b0a3eef5

Local validation used Windows amd64 with Go 1.26.10, the version pinned by go.mod and selected automatically through GOTOOLCHAIN=auto.

Limitations

• The suite was executed on Windows amd64 only. The macOS lock_unix.go and identity_unix.go paths were not exercised on a real macOS machine.
• TestFingerprintRefusesFilesSymlinksAndMissingRoots skipped locally because symlink creation is not available for this account on Windows; the Linux CI run exercised it instead.
• No end-to-end check against real credential files or a real OAuth flow. This PR only covers pure local unit behavior.
• internal/llm, the OpenAPI contract, and every frontend file are untouched, so npm run check:api and the frontend suites were not run.

Checklist

• My code follows the project's coding style (go fmt, go vet)
• I have performed a self-review of my code
• I have added tests that prove my fix is effective or my feature works
• New and existing unit tests pass locally with my changes — the two changed packages, their downstream consumers, and the CI Go checks gate pass; the single internal/app failure seen during the full local run also fails on the untouched base
• I have updated the documentation accordingly (if applicable) — not applicable, this is a test-only change
• I have signed the CLA — to be confirmed by the contributor before merge
• I did not use AI/LLM to create this PR, or I disclosed the tool/model below and reviewed its output; I did not attribute commits to AI and will answer maintainer questions and review comments myself without AI/LLM.
  • The commit in this PR is authored by the MiniMax-AI-Dev account, so the "no AI attribution in commits" clause does not hold here. The tool and model are disclosed below, the contributor has reviewed the generated tests, and the contributor will answer maintainer questions and review comments.

AI Assistance

The tests, the validation runs, and this description were prepared with MiniMax Code using the MiniMax M3.1 Flash model. The single commit is authored by the MiniMax-AI-Dev GitHub account. The contributor has reviewed the generated tests and remains responsible for answering maintainer questions and review comments.

Related Issues

None.