[vite-plugin] Vitest fails at startup since 1.58.0: "There is already a server associated with the config."

Finding: In an external report, running `vitest run` (vitest 5.0.2, vite 8.3.1, wrangler 4.144.0, Node 24.18.0, pnpm 12.6.0, macOS arm64) in a project whose Vite config includes `cloudflare()` from @cloudflare/vite-plugin fails at startup with "There is already a server associated with the config." on plugin 1.58.0 and 1.62.2, while 1.57.3 passes (https://github.com/cloudflare/workers-sdk/issues/15969). The reporter's results table also shows that 1.62.2 passes when `cloudflare()` is removed from the plugins array of the single vite.config.ts, and the reporter says a jsdom test environment makes no difference. Reported evidence: the reporter supplies a five-file minimal reproduction and a stack trace running from Vite `_createServer` through Vitest `createViteServer`, `createClusterServer` and `attachProjectsFromEntries` (https://github.com/cloudflare/workers-sdk/issues/15969). An automated triage comment, itself an LLM-generated summary that may contain errors, states it reproduced the failure once on the pinned versions and that 1.57.3 passed in a baseline run (https://github.com/cloudflare/workers-sdk/issues/15969#issuecomment-5912340795). It labels the issue a regression. This is external-report and automated-triage evidence only, not an independent human reproduction. Hypothesis, not confirmed: the reporter, reading the 1.62.2 dist, attributes the failure to the container cleanup added in 1.58.0 (#15765). They say `getDevContainerCleanup` replaces `server.config` with a copy, Vitest 5 matches projects to servers by config object identity, the lookup misses, and Vitest calls `createServer()` again, which trips Vite's guard against reusing a config (https://github.com/cloudflare/workers-sdk/issues/15969). No maintainer has confirmed this in the supplied data. The reporter's suggested code fix, a module-level WeakMap or in-place mutation, is a suggestion only. Status: the issue is open. No fix commit or released fix appears in the supplied sources. Limitations: this is one issue, on one OS and package manager, with possibly omitted middle comments. KFA did not reproduce it. The reporter's table records outcomes only: 1.57.3 passes, and 1.62.2 with `cloudflare()` removed from the plugins array of the single vite.config.ts passes. The source does not present either as a recommended workaround, and it does not report testing a separate test-only config without the plugin. Neither outcome is verified by KFA.