test(setup): one answer for CODEMAN_DATA_DIR, the strip from #371

#356 and #371 fixed the same leak two ways. #356 pointed CODEMAN_DATA_DIR at a
second throwaway directory and cleaned it up in afterAll and on exit; #371
deletes the variable along with CODEMAN_INSTANCE and CODEMAN_TMUX_SOCKET, so
`getDataDir()` falls back to `homedir()`, which the temp HOME already redirects.
Merged as they were, setup.ts set the variable and deleted it a few lines
later, and the second directory was created for nothing.

The strip wins: same protection, one tree to clean up, and the isolation test
#371 adds pins the list statically. The extra directory, its restore and its
two rmSync calls go, the vitest config `env` entries that set the same variable
go (they were documented as inert and would now be contradicted by the setup
file either way), the two test comments that described the old mechanism are
reworded, and CLAUDE.md's testing paragraph names the three stripped variables
and why CODEMAN_INSTANCE has to be stripped in the setup file rather than a hook.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qg6bcATm1pNNY4kQWGwzgu

CLAUDE.md

@@ -407,7 +407,7 @@ Raw `npx vitest` skips the config (and with it `setup.ts`); always use `npm test
 
 **Config**: Vitest with `globals: true`, `fileParallelism: false`. Timeout 30s, teardown 60s. `config/vitest.config.ts` is the everything-config behind `test:all`; `config/vitest.ci.config.ts` is the gate and derives its excludes from `config/test-suites.ts`, which is also what `vitest.browser.config.ts` and `vitest.perf.config.ts` derive their includes from — so the exclusions and the runners cannot drift apart. Keep shared options in sync across them.
 
-**Tmux safety**: under vitest (`VITEST` env var, set automatically), `TmuxManager` no-ops ALL shell commands and becomes a pure in-memory mock — tests physically cannot create/kill/attach real tmux sessions (`IS_TEST_MODE` in `src/tmux-manager.ts`). Every docker IO path is no-op'd the same way. `Session` is test-gated too: instead of attaching a real tmux client, it spawns a raw-mode echo PTY (`TEST_PTY_SCRIPT` in `src/session.ts`), so integration tests get a live input/output loop that echoes each byte exactly once. `test/setup.ts` gives every test file a temporary `HOME`/`USERPROFILE` (all `homedir()`-derived state, `~/.codeman` and `~/codeman-cases` included, resolves into a per-file fixture; the Playwright browser cache path is preserved), and additionally strips `CODEMAN_PASSWORD`/`CODEMAN_USERNAME` (so auth state from the running instance can't leak into tests) and `CODEMAN_GESTURE` (a shell-exported gesture flag would flip render-injection assertions), and points `CODEMAN_DATA_DIR` at a throwaway dir (#356). ⚠️ That last one is what actually protects `~/.codeman`: `getDataDir()` reads `CODEMAN_DATA_DIR` as an ABSOLUTE override before it ever looks at `homedir()`, so one inherited from the shell (a second instance, a beta run) bypasses the temp HOME entirely, and a bare suite run once overwrote the real `remote-hosts.json` with a route test's fixture. `os.homedir()` itself DOES follow `$HOME`, so the temp HOME is what redirects everything else. Tests that delete case trees go through `safeRmHomeTree()` (`test/mocks`), which refuses any path outside the temp HOME, so a wrong anchor leaves a temp dir behind instead of deleting `~/codeman-cases`. ⚠️ Raw `npx vitest` without `--config` skips `setup.ts` and with it the temp-HOME isolation.
+**Tmux safety**: under vitest (`VITEST` env var, set automatically), `TmuxManager` no-ops ALL shell commands and becomes a pure in-memory mock — tests physically cannot create/kill/attach real tmux sessions (`IS_TEST_MODE` in `src/tmux-manager.ts`). Every docker IO path is no-op'd the same way. `Session` is test-gated too: instead of attaching a real tmux client, it spawns a raw-mode echo PTY (`TEST_PTY_SCRIPT` in `src/session.ts`), so integration tests get a live input/output loop that echoes each byte exactly once. `test/setup.ts` gives every test file a temporary `HOME`/`USERPROFILE` (all `homedir()`-derived state, `~/.codeman` and `~/codeman-cases` included, resolves into a per-file fixture; the Playwright browser cache path is preserved), and additionally strips `CODEMAN_PASSWORD`/`CODEMAN_USERNAME` (so auth state from the running instance can't leak into tests) and `CODEMAN_GESTURE` (a shell-exported gesture flag would flip render-injection assertions), and strips the three instance-selection vars `CODEMAN_INSTANCE`/`CODEMAN_DATA_DIR`/`CODEMAN_TMUX_SOCKET` (#356/#371; `test/test-env-isolation.test.ts` pins the list, and its STATIC half reads setup.ts so a dropped `delete` fails everywhere rather than only on a box that exports the var). ⚠️ `CODEMAN_DATA_DIR` is the one that matters: `getDataDir()` reads it as an ABSOLUTE override before it ever looks at `homedir()`, so one inherited from the shell (a second instance, a beta run, a shell left over from `codeman web -d`) bypasses the temp HOME entirely, and a bare suite run once overwrote the real `remote-hosts.json` with a route test's fixture. `os.homedir()` itself DOES follow `$HOME`, so the temp HOME is what redirects everything else; `CODEMAN_INSTANCE` must be stripped in the setup file and never in a hook, because `config/instance.ts` captures it into a module-level const on first import. Tests that delete case trees go through `safeRmHomeTree()` (`test/mocks`), which refuses any path outside the temp HOME, so a wrong anchor leaves a temp dir behind instead of deleting `~/codeman-cases`. ⚠️ Raw `npx vitest` without `--config` skips `setup.ts` and with it the temp-HOME isolation.
 
 **Ports**: Pick unique ports manually, 3150+. Search `const PORT =` before adding new tests. Never 3000 (the live instance).