diff --git a/AGENTS.md b/AGENTS.md
index d8306d9bdb8..e89c819844e 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -1289,65 +1289,22 @@ scripts/run_tests.sh                                  # full suite, CI-parity
 scripts/run_tests.sh tests/gateway/                   # one directory
 scripts/run_tests.sh tests/agent/test_foo.py::test_x  # one test
 scripts/run_tests.sh -v --tb=long                     # pass-through pytest flags
-scripts/run_tests.sh --no-isolate tests/foo/          # disable subprocess isolation (faster, for debugging)
 ```
 
-### Subprocess-per-test isolation
+### Subprocess-per-test-file isolation
 
-Every test runs in a freshly-spawned Python subprocess via the in-tree plugin
-at `tests/_isolate_plugin.py`. This means module-level dicts/sets and
-ContextVars from one test cannot leak into the next — the historic
-`_reset_module_state` autouse fixture is gone.
+Every test file runs in a freshly-spawned Python subprocess via `run_tests_parallel.py`. This means module-level dicts/sets and
+ContextVars from one test file cannot leak into the next.
 
-Implementation notes:
+### Why the wrapper
 
-- The plugin uses `multiprocessing.get_context("spawn")`, which works on
-  Linux, macOS, and Windows alike (POSIX `fork` is not used).
-- Per-test overhead is ~0.5–1.0s (Python startup + pytest collection). xdist
-  parallelism amortizes this across cores; on a 20-core box the full suite
-  finishes in roughly the same wall time as before, but flake-free.
-- `isolate_timeout` (configured in `pyproject.toml`) caps each test at 30s.
-  Hangs are killed and surfaced as a failure report.
-- Pass `--no-isolate` to disable isolation — useful when debugging a single
-  test interactively, or when you specifically want to verify state leakage.
-- The plugin disables itself in child processes (sentinel envvar
-  `HERMES_ISOLATE_CHILD=1`), so there's no fork-bomb risk.
+|                     | Without wrapper                             | With wrapper                              |
+| ------------------- | ------------------------------------------- | ----------------------------------------- |
+| Provider API keys   | Whatever is in your env (auto-detects pool) | All env vars except a specific few unset. |
+| HOME / `~/.hermes/` | Your real config+auth.json                  | Temp dir per test                         |
+| Timezone            | Local TZ (PDT etc.)                         | UTC                                       |
+| Locale              | Whatever is set                             | C.UTF-8                                   |
 
-### Why the wrapper (and why the old "just call pytest" doesn't work)
-
-Five real sources of local-vs-CI drift the script closes:
-
-| | Without wrapper | With wrapper |
-|---|---|---|
-| Provider API keys | Whatever is in your env (auto-detects pool) | All `*_API_KEY`/`*_TOKEN`/etc. unset |
-| HOME / `~/.hermes/` | Your real config+auth.json | Temp dir per test |
-| Timezone | Local TZ (PDT etc.) | UTC |
-| Locale | Whatever is set | C.UTF-8 |
-| xdist workers | `-n auto` = all cores | `-n auto` (safe — subprocess isolation prevents cross-worker flakes) |
-
-`tests/conftest.py` also enforces points 1-4 as an autouse fixture so ANY pytest
-invocation (including IDE integrations) gets hermetic behavior — but the wrapper
-is belt-and-suspenders.
-
-### Running without the wrapper (only if you must)
-
-If you can't use the wrapper (e.g. inside an IDE that shells pytest directly),
-at minimum activate the venv. The isolation plugin loads automatically from
-`addopts` in `pyproject.toml`, so you get the same per-test process isolation
-either way.
-
-```bash
-source .venv/bin/activate   # or: source venv/bin/activate
-python -m pytest tests/ -q
-```
-
-If you need to bypass isolation for fast feedback while debugging:
-
-```bash
-python -m pytest tests/agent/test_foo.py -q --no-isolate
-```
-
-Always run the full suite before pushing changes.
 
 ### Don't write change-detector tests