flake: TestSyncCommands_Golden/start_with_dependencies

[flake-investigator]

CI Run: https://github.com/coder/coder/actions/runs/22639933232
Failing job: https://github.com/coder/coder/actions/runs/22639933232/job/65613285949
Commit: 6acdd6ca7d3cd935a3c23c424a47acffafb50388 (Danielle Maywood) — fix: wire agents-tab-visible metadata to experiments flag (#22553)

Summary
TestSyncCommands_Golden/start_with_dependencies failed on Windows with a golden file mismatch. The output sometimes skips the expected “Waiting for dependencies…” line and only prints “Success”, indicating a timing-dependent flaky test.

Failure evidence

=== FAIL: cli TestSyncCommands_Golden/start_with_dependencies (0.28s)
    clitest.go:86: invoking command: coder --global-config C:\Users\ADMINI~1\AppData\Local\Temp\TestSyncCommands_Goldenstart_with_dependencies2007397451\001 exp sync start test-unit --socket-path \\.\pipe\com.coder.agentsocket_test.TestSyncCommands_Golden/start_with_dependencies.EB5P5CXMZFVKOTNIWWZ2JHK2RW
    golden.go:192:
        Error:       Should be empty, but was  string(
            -   "Waiting for dependencies of unit 'test-unit' to be satisfied...\nSuccess\n",
            +   "Success\n",
          )
        Messages:   golden file mismatch (-want +got): testdata\TestSyncCommands_Golden\start_with_dependencies.golden

Root cause classification

• Flaky test (timing): the test relies on time.Sleep(100 * time.Millisecond) to ensure the “Waiting…” line appears. On Windows, the dependency completes quickly enough that the waiting message is skipped, causing the golden mismatch.
• No data race / panic / OOM indicators found.

Assignment analysis

• Function-level blame (git blame -L) isn’t available via current tooling.
• Used git log --oneline -10 --follow cli/sync_test.go to find recent meaningful changes.
• Most recent relevant change: 1069ce6e “feat: add support for agentsock on Windows (#22171)” by Spike Curtis, which introduced/updated Windows sync behavior and touches this test file.
• Assigning to @spikecurtis for triage.

Related issues searched (none found)

• “TestSyncCommands_Golden”
• “start_with_dependencies”
• “exp sync”
• Closed issues updated in last 30 days with “TestSyncCommands”

Reproduction (best effort)

• Windows: go test ./cli -run TestSyncCommands_Golden/start_with_dependencies -count=1

Suggested next steps

• Make the test output deterministic (e.g., explicit synchronization/ready signal instead of fixed sleep) or relax golden expectations for the optional waiting line on fast paths.