#3393 Flaky test: AccessDataPoller "a grant created by a real method run through A stays staged on A and reaches B" fails under full-suite load

What happens

integration/serve_filesystem_access_data_poller_test.ts, test "AccessDataPoller: a grant created by a real method run through A stays staged on A and reaches B", fails intermittently when the whole suite runs:

AssertionError: Values are not equal: A's own run stays staged
-   allow
+   deny

How often

On plain main at 91d688f1 (no local changes), deno run test failed on this test in 2 of 6 full runs. The file passes when run alone (3 of 3), and deno run test integration passed 3 of 3, so it needs the load of the full parallel suite.

It also failed the run-tests step of a verify-build run for an unrelated branch (swamp-club#2528), which is how it was found.

Likely cause

The test starts poller A, runs a real grant create through A, waits for B to apply it, waits two more poll cycles on A, and then asserts A still decides deny. Under load, A's poller appears to treat the run's own writes (the data versions, or the method-summary report written into the grant directory after the ModelUpdated event) as a peer change and applies the grant. Either the product has a window where a serve instance's own run reads as a peer change, or the test's two-cycle wait races the event that marks those writes as its own. The test was added with swamp-club#3371.

Expected

The test passes under deno run test and deno test --repeats, or the window is closed if it is a real one.