Target: <2min CI test wall time.

Runs the Tests workflow as a 4-way matrix instead of one job. Each
shard runs ~3,000 tests on its own ubuntu-latest runner (4 cores) with
-n auto xdist inside. Total effective parallelism: 16 workers across
4 machines (vs 4 workers on 1 machine today).

Was previously tried in #11566 and closed — shard 3 hung at 97% complete
for 100+ seconds with dozens of E/F markers. Root cause was cross-test
pollution exposed by splitting test files across shards (e.g. the three
test files that mutated sys.modules['dotenv'] at import time poisoned
whichever shard they landed in). That's now fixed by #11453 and #11577:
conftest is hermetic, the dotenv stub bombs are removed, and tests no
longer depend on each other's env-var side effects.

Changes:
- pyproject.toml: add pytest-split>=0.9,<1 to dev extras
- .github/workflows/tests.yml: 'test' job becomes matrix-split into 4
  groups with fail-fast: false. Runs 'pytest --splits 4 --group N'.
  pytest-split composes with -n auto from pyproject addopts.

e2e job is unchanged (already small, 20s).

Expected timing:
  Before: ~4m total (243s test step + ~25s setup)
  After:  ~90-115s total (shard wall time ~60-90s + ~25s setup)

Hash-based split is deterministic; no .test_durations file needed yet.
Can add one later via --store-durations for better shard balance.

Target: <2min CI test wall time.

Runs the Tests workflow as a 4-way matrix instead of one job. Each
shard runs ~3,000 tests on its own ubuntu-latest runner (4 cores) with
-n auto xdist inside. Total effective parallelism: 16 workers across
4 machines (vs 4 workers on 1 machine today).

Was previously tried in #11566 and closed — shard 3 hung at 97% complete
for 100+ seconds with dozens of E/F markers. Root cause was cross-test
pollution exposed by splitting test files across shards (e.g. the three
test files that mutated sys.modules['dotenv'] at import time poisoned
whichever shard they landed in). That's now fixed by #11453 and #11577:
conftest is hermetic, the dotenv stub bombs are removed, and tests no
longer depend on each other's env-var side effects.

Changes:
- pyproject.toml: add pytest-split>=0.9,<1 to dev extras
- .github/workflows/tests.yml: 'test' job becomes matrix-split into 4
  groups with fail-fast: false. Runs 'pytest --splits 4 --group N'.
  pytest-split composes with -n auto from pyproject addopts.

e2e job is unchanged (already small, 20s).

Expected timing:
  Before: ~4m total (243s test step + ~25s setup)
  After:  ~90-115s total (shard wall time ~60-90s + ~25s setup)

Hash-based split is deterministic; no .test_durations file needed yet.
Can add one later via --store-durations for better shard balance.

….sh (NousResearch#11577)

* test: make test env hermetic; enforce CI parity via scripts/run_tests.sh

Fixes the recurring 'works locally, fails in CI' (and vice versa) class
of flakes by making tests hermetic and providing a canonical local runner
that matches CI's environment.

## Layer 1 — hermetic conftest.py (tests/conftest.py)

Autouse fixture now unsets every credential-shaped env var before every
test, so developer-local API keys can't leak into tests that assert
'auto-detect provider when key present'.

Pattern: unset any var ending in _API_KEY, _TOKEN, _SECRET, _PASSWORD,
_CREDENTIALS, _ACCESS_KEY, _PRIVATE_KEY, etc. Plus an explicit list of
credential names that don't fit the suffix pattern (AWS_ACCESS_KEY_ID,
FAL_KEY, GH_TOKEN, etc.) and all the provider BASE_URL overrides that
change auto-detect behavior.

Also unsets HERMES_* behavioral vars (HERMES_YOLO_MODE, HERMES_QUIET,
HERMES_SESSION_*, etc.) that mutate agent behavior.

Also:
  - Redirects HOME to a per-test tempdir (not just HERMES_HOME), so
    code reading ~/.hermes/* directly can't touch the real dir.
  - Pins TZ=UTC, LANG=C.UTF-8, LC_ALL=C.UTF-8, PYTHONHASHSEED=0 to
    match CI's deterministic runtime.

The old _isolate_hermes_home fixture name is preserved as an alias so
any test that yields it explicitly still works.

## Layer 2 — scripts/run_tests.sh canonical runner

'Always use scripts/run_tests.sh, never call pytest directly' is the
new rule (documented in AGENTS.md). The script:
  - Unsets all credential env vars (belt-and-suspenders for callers
    who bypass conftest — e.g. IDE integrations)
  - Pins TZ/LANG/PYTHONHASHSEED
  - Uses -n 4 xdist workers (matches GHA ubuntu-latest; -n auto on
    a 20-core workstation surfaces test-ordering flakes CI will never
    see, causing the infamous 'passes in CI, fails locally' drift)
  - Finds the venv in .venv, venv, or main checkout's venv
  - Passes through arbitrary pytest args

Installs pytest-split on demand so the script can also be used to run
matrix-split subsets locally for debugging.

## Remove 3 module-level dotenv stubs that broke test isolation

tests/hermes_cli/test_{arcee,xiaomi,api_key}_provider.py each had a
module-level:

    if 'dotenv' not in sys.modules:
        fake_dotenv = types.ModuleType('dotenv')
        fake_dotenv.load_dotenv = lambda *a, **kw: None
        sys.modules['dotenv'] = fake_dotenv

This patches sys.modules['dotenv'] to a fake at import time with no
teardown. Under pytest-xdist LoadScheduling, whichever worker collected
one of these files first poisoned its sys.modules; subsequent tests in
the same worker that imported load_dotenv transitively (e.g.
test_env_loader.py via hermes_cli.env_loader) got the no-op lambda and
saw their assertions fail.

dotenv is a required dependency (python-dotenv>=1.2.1 in pyproject.toml),
so the defensive stub was never needed. Removed.

## Validation

- tests/hermes_cli/ alone: 2178 passed, 1 skipped, 0 failed (was 4
  failures in test_env_loader.py before this fix)
- tests/test_plugin_skills.py, tests/hermes_cli/test_plugins.py,
  tests/test_hermes_logging.py combined: 123 passed (the caplog
  regression tests from PR NousResearch#11453 still pass)
- Local full run shows no F/E clusters in the 0-55% range that were
  previously present before the conftest hardening

## Background

See AGENTS.md 'Testing' section for the full list of drift sources
this closes. Matrix split (closed as NousResearch#11566) will be re-attempted
once this foundation lands — cross-test pollution was the root cause
of the shard-3 hang in that PR.

* fix(conftest): don't redirect HOME — it broke CI subprocesses

PR NousResearch#11577's autouse fixture was setting HOME to a per-test tempdir.
CI started timing out at 97% complete with dozens of E/F markers and
orphan python processes at cleanup — tests (or transitive deps)
spawn subprocesses that expect a stable HOME, and the redirect broke
them in non-obvious ways.

Env-var unsetting and TZ/LANG/hashseed pinning (the actual CI-drift
fixes) are unchanged and still in place. HERMES_HOME redirection is
also unchanged — that's the canonical way to isolate tests from
~/.hermes/, not HOME.

Any code in the codebase reading ~/.hermes/* via `Path.home() / ".hermes"`
instead of `get_hermes_home()` is a bug to fix at the callsite, not
something to paper over in conftest.

….sh (NousResearch#11577)

* test: make test env hermetic; enforce CI parity via scripts/run_tests.sh

Fixes the recurring 'works locally, fails in CI' (and vice versa) class
of flakes by making tests hermetic and providing a canonical local runner
that matches CI's environment.

## Layer 1 — hermetic conftest.py (tests/conftest.py)

Autouse fixture now unsets every credential-shaped env var before every
test, so developer-local API keys can't leak into tests that assert
'auto-detect provider when key present'.

Pattern: unset any var ending in _API_KEY, _TOKEN, _SECRET, _PASSWORD,
_CREDENTIALS, _ACCESS_KEY, _PRIVATE_KEY, etc. Plus an explicit list of
credential names that don't fit the suffix pattern (AWS_ACCESS_KEY_ID,
FAL_KEY, GH_TOKEN, etc.) and all the provider BASE_URL overrides that
change auto-detect behavior.

Also unsets HERMES_* behavioral vars (HERMES_YOLO_MODE, HERMES_QUIET,
HERMES_SESSION_*, etc.) that mutate agent behavior.

Also:
  - Redirects HOME to a per-test tempdir (not just HERMES_HOME), so
    code reading ~/.hermes/* directly can't touch the real dir.
  - Pins TZ=UTC, LANG=C.UTF-8, LC_ALL=C.UTF-8, PYTHONHASHSEED=0 to
    match CI's deterministic runtime.

The old _isolate_hermes_home fixture name is preserved as an alias so
any test that yields it explicitly still works.

## Layer 2 — scripts/run_tests.sh canonical runner

'Always use scripts/run_tests.sh, never call pytest directly' is the
new rule (documented in AGENTS.md). The script:
  - Unsets all credential env vars (belt-and-suspenders for callers
    who bypass conftest — e.g. IDE integrations)
  - Pins TZ/LANG/PYTHONHASHSEED
  - Uses -n 4 xdist workers (matches GHA ubuntu-latest; -n auto on
    a 20-core workstation surfaces test-ordering flakes CI will never
    see, causing the infamous 'passes in CI, fails locally' drift)
  - Finds the venv in .venv, venv, or main checkout's venv
  - Passes through arbitrary pytest args

Installs pytest-split on demand so the script can also be used to run
matrix-split subsets locally for debugging.

## Remove 3 module-level dotenv stubs that broke test isolation

tests/hermes_cli/test_{arcee,xiaomi,api_key}_provider.py each had a
module-level:

    if 'dotenv' not in sys.modules:
        fake_dotenv = types.ModuleType('dotenv')
        fake_dotenv.load_dotenv = lambda *a, **kw: None
        sys.modules['dotenv'] = fake_dotenv

This patches sys.modules['dotenv'] to a fake at import time with no
teardown. Under pytest-xdist LoadScheduling, whichever worker collected
one of these files first poisoned its sys.modules; subsequent tests in
the same worker that imported load_dotenv transitively (e.g.
test_env_loader.py via hermes_cli.env_loader) got the no-op lambda and
saw their assertions fail.

dotenv is a required dependency (python-dotenv>=1.2.1 in pyproject.toml),
so the defensive stub was never needed. Removed.

## Validation

- tests/hermes_cli/ alone: 2178 passed, 1 skipped, 0 failed (was 4
  failures in test_env_loader.py before this fix)
- tests/test_plugin_skills.py, tests/hermes_cli/test_plugins.py,
  tests/test_hermes_logging.py combined: 123 passed (the caplog
  regression tests from PR NousResearch#11453 still pass)
- Local full run shows no F/E clusters in the 0-55% range that were
  previously present before the conftest hardening

## Background

See AGENTS.md 'Testing' section for the full list of drift sources
this closes. Matrix split (closed as NousResearch#11566) will be re-attempted
once this foundation lands — cross-test pollution was the root cause
of the shard-3 hang in that PR.

* fix(conftest): don't redirect HOME — it broke CI subprocesses

PR NousResearch#11577's autouse fixture was setting HOME to a per-test tempdir.
CI started timing out at 97% complete with dozens of E/F markers and
orphan python processes at cleanup — tests (or transitive deps)
spawn subprocesses that expect a stable HOME, and the redirect broke
them in non-obvious ways.

Env-var unsetting and TZ/LANG/hashseed pinning (the actual CI-drift
fixes) are unchanged and still in place. HERMES_HOME redirection is
also unchanged — that's the canonical way to isolate tests from
~/.hermes/, not HOME.

Any code in the codebase reading ~/.hermes/* via `Path.home() / ".hermes"`
instead of `get_hermes_home()` is a bug to fix at the callsite, not
something to paper over in conftest.

….sh (NousResearch#11577)

* test: make test env hermetic; enforce CI parity via scripts/run_tests.sh

Fixes the recurring 'works locally, fails in CI' (and vice versa) class
of flakes by making tests hermetic and providing a canonical local runner
that matches CI's environment.

## Layer 1 — hermetic conftest.py (tests/conftest.py)

Autouse fixture now unsets every credential-shaped env var before every
test, so developer-local API keys can't leak into tests that assert
'auto-detect provider when key present'.

Pattern: unset any var ending in _API_KEY, _TOKEN, _SECRET, _PASSWORD,
_CREDENTIALS, _ACCESS_KEY, _PRIVATE_KEY, etc. Plus an explicit list of
credential names that don't fit the suffix pattern (AWS_ACCESS_KEY_ID,
FAL_KEY, GH_TOKEN, etc.) and all the provider BASE_URL overrides that
change auto-detect behavior.

Also unsets HERMES_* behavioral vars (HERMES_YOLO_MODE, HERMES_QUIET,
HERMES_SESSION_*, etc.) that mutate agent behavior.

Also:
  - Redirects HOME to a per-test tempdir (not just HERMES_HOME), so
    code reading ~/.hermes/* directly can't touch the real dir.
  - Pins TZ=UTC, LANG=C.UTF-8, LC_ALL=C.UTF-8, PYTHONHASHSEED=0 to
    match CI's deterministic runtime.

The old _isolate_hermes_home fixture name is preserved as an alias so
any test that yields it explicitly still works.

## Layer 2 — scripts/run_tests.sh canonical runner

'Always use scripts/run_tests.sh, never call pytest directly' is the
new rule (documented in AGENTS.md). The script:
  - Unsets all credential env vars (belt-and-suspenders for callers
    who bypass conftest — e.g. IDE integrations)
  - Pins TZ/LANG/PYTHONHASHSEED
  - Uses -n 4 xdist workers (matches GHA ubuntu-latest; -n auto on
    a 20-core workstation surfaces test-ordering flakes CI will never
    see, causing the infamous 'passes in CI, fails locally' drift)
  - Finds the venv in .venv, venv, or main checkout's venv
  - Passes through arbitrary pytest args

Installs pytest-split on demand so the script can also be used to run
matrix-split subsets locally for debugging.

## Remove 3 module-level dotenv stubs that broke test isolation

tests/hermes_cli/test_{arcee,xiaomi,api_key}_provider.py each had a
module-level:

    if 'dotenv' not in sys.modules:
        fake_dotenv = types.ModuleType('dotenv')
        fake_dotenv.load_dotenv = lambda *a, **kw: None
        sys.modules['dotenv'] = fake_dotenv

This patches sys.modules['dotenv'] to a fake at import time with no
teardown. Under pytest-xdist LoadScheduling, whichever worker collected
one of these files first poisoned its sys.modules; subsequent tests in
the same worker that imported load_dotenv transitively (e.g.
test_env_loader.py via hermes_cli.env_loader) got the no-op lambda and
saw their assertions fail.

dotenv is a required dependency (python-dotenv>=1.2.1 in pyproject.toml),
so the defensive stub was never needed. Removed.

## Validation

- tests/hermes_cli/ alone: 2178 passed, 1 skipped, 0 failed (was 4
  failures in test_env_loader.py before this fix)
- tests/test_plugin_skills.py, tests/hermes_cli/test_plugins.py,
  tests/test_hermes_logging.py combined: 123 passed (the caplog
  regression tests from PR NousResearch#11453 still pass)
- Local full run shows no F/E clusters in the 0-55% range that were
  previously present before the conftest hardening

## Background

See AGENTS.md 'Testing' section for the full list of drift sources
this closes. Matrix split (closed as NousResearch#11566) will be re-attempted
once this foundation lands — cross-test pollution was the root cause
of the shard-3 hang in that PR.

* fix(conftest): don't redirect HOME — it broke CI subprocesses

PR NousResearch#11577's autouse fixture was setting HOME to a per-test tempdir.
CI started timing out at 97% complete with dozens of E/F markers and
orphan python processes at cleanup — tests (or transitive deps)
spawn subprocesses that expect a stable HOME, and the redirect broke
them in non-obvious ways.

Env-var unsetting and TZ/LANG/hashseed pinning (the actual CI-drift
fixes) are unchanged and still in place. HERMES_HOME redirection is
also unchanged — that's the canonical way to isolate tests from
~/.hermes/, not HOME.

Any code in the codebase reading ~/.hermes/* via `Path.home() / ".hermes"`
instead of `get_hermes_home()` is a bug to fix at the callsite, not
something to paper over in conftest.

….sh (NousResearch#11577)

* test: make test env hermetic; enforce CI parity via scripts/run_tests.sh

Fixes the recurring 'works locally, fails in CI' (and vice versa) class
of flakes by making tests hermetic and providing a canonical local runner
that matches CI's environment.

## Layer 1 — hermetic conftest.py (tests/conftest.py)

Autouse fixture now unsets every credential-shaped env var before every
test, so developer-local API keys can't leak into tests that assert
'auto-detect provider when key present'.

Pattern: unset any var ending in _API_KEY, _TOKEN, _SECRET, _PASSWORD,
_CREDENTIALS, _ACCESS_KEY, _PRIVATE_KEY, etc. Plus an explicit list of
credential names that don't fit the suffix pattern (AWS_ACCESS_KEY_ID,
FAL_KEY, GH_TOKEN, etc.) and all the provider BASE_URL overrides that
change auto-detect behavior.

Also unsets HERMES_* behavioral vars (HERMES_YOLO_MODE, HERMES_QUIET,
HERMES_SESSION_*, etc.) that mutate agent behavior.

Also:
  - Redirects HOME to a per-test tempdir (not just HERMES_HOME), so
    code reading ~/.hermes/* directly can't touch the real dir.
  - Pins TZ=UTC, LANG=C.UTF-8, LC_ALL=C.UTF-8, PYTHONHASHSEED=0 to
    match CI's deterministic runtime.

The old _isolate_hermes_home fixture name is preserved as an alias so
any test that yields it explicitly still works.

## Layer 2 — scripts/run_tests.sh canonical runner

'Always use scripts/run_tests.sh, never call pytest directly' is the
new rule (documented in AGENTS.md). The script:
  - Unsets all credential env vars (belt-and-suspenders for callers
    who bypass conftest — e.g. IDE integrations)
  - Pins TZ/LANG/PYTHONHASHSEED
  - Uses -n 4 xdist workers (matches GHA ubuntu-latest; -n auto on
    a 20-core workstation surfaces test-ordering flakes CI will never
    see, causing the infamous 'passes in CI, fails locally' drift)
  - Finds the venv in .venv, venv, or main checkout's venv
  - Passes through arbitrary pytest args

Installs pytest-split on demand so the script can also be used to run
matrix-split subsets locally for debugging.

## Remove 3 module-level dotenv stubs that broke test isolation

tests/hermes_cli/test_{arcee,xiaomi,api_key}_provider.py each had a
module-level:

    if 'dotenv' not in sys.modules:
        fake_dotenv = types.ModuleType('dotenv')
        fake_dotenv.load_dotenv = lambda *a, **kw: None
        sys.modules['dotenv'] = fake_dotenv

This patches sys.modules['dotenv'] to a fake at import time with no
teardown. Under pytest-xdist LoadScheduling, whichever worker collected
one of these files first poisoned its sys.modules; subsequent tests in
the same worker that imported load_dotenv transitively (e.g.
test_env_loader.py via hermes_cli.env_loader) got the no-op lambda and
saw their assertions fail.

dotenv is a required dependency (python-dotenv>=1.2.1 in pyproject.toml),
so the defensive stub was never needed. Removed.

## Validation

- tests/hermes_cli/ alone: 2178 passed, 1 skipped, 0 failed (was 4
  failures in test_env_loader.py before this fix)
- tests/test_plugin_skills.py, tests/hermes_cli/test_plugins.py,
  tests/test_hermes_logging.py combined: 123 passed (the caplog
  regression tests from PR NousResearch#11453 still pass)
- Local full run shows no F/E clusters in the 0-55% range that were
  previously present before the conftest hardening

## Background

See AGENTS.md 'Testing' section for the full list of drift sources
this closes. Matrix split (closed as NousResearch#11566) will be re-attempted
once this foundation lands — cross-test pollution was the root cause
of the shard-3 hang in that PR.

* fix(conftest): don't redirect HOME — it broke CI subprocesses

PR NousResearch#11577's autouse fixture was setting HOME to a per-test tempdir.
CI started timing out at 97% complete with dozens of E/F markers and
orphan python processes at cleanup — tests (or transitive deps)
spawn subprocesses that expect a stable HOME, and the redirect broke
them in non-obvious ways.

Env-var unsetting and TZ/LANG/hashseed pinning (the actual CI-drift
fixes) are unchanged and still in place. HERMES_HOME redirection is
also unchanged — that's the canonical way to isolate tests from
~/.hermes/, not HOME.

Any code in the codebase reading ~/.hermes/* via `Path.home() / ".hermes"`
instead of `get_hermes_home()` is a bug to fix at the callsite, not
something to paper over in conftest.

….sh (NousResearch#11577)

* test: make test env hermetic; enforce CI parity via scripts/run_tests.sh

Fixes the recurring 'works locally, fails in CI' (and vice versa) class
of flakes by making tests hermetic and providing a canonical local runner
that matches CI's environment.

## Layer 1 — hermetic conftest.py (tests/conftest.py)

Autouse fixture now unsets every credential-shaped env var before every
test, so developer-local API keys can't leak into tests that assert
'auto-detect provider when key present'.

Pattern: unset any var ending in _API_KEY, _TOKEN, _SECRET, _PASSWORD,
_CREDENTIALS, _ACCESS_KEY, _PRIVATE_KEY, etc. Plus an explicit list of
credential names that don't fit the suffix pattern (AWS_ACCESS_KEY_ID,
FAL_KEY, GH_TOKEN, etc.) and all the provider BASE_URL overrides that
change auto-detect behavior.

Also unsets HERMES_* behavioral vars (HERMES_YOLO_MODE, HERMES_QUIET,
HERMES_SESSION_*, etc.) that mutate agent behavior.

Also:
  - Redirects HOME to a per-test tempdir (not just HERMES_HOME), so
    code reading ~/.hermes/* directly can't touch the real dir.
  - Pins TZ=UTC, LANG=C.UTF-8, LC_ALL=C.UTF-8, PYTHONHASHSEED=0 to
    match CI's deterministic runtime.

The old _isolate_hermes_home fixture name is preserved as an alias so
any test that yields it explicitly still works.

## Layer 2 — scripts/run_tests.sh canonical runner

'Always use scripts/run_tests.sh, never call pytest directly' is the
new rule (documented in AGENTS.md). The script:
  - Unsets all credential env vars (belt-and-suspenders for callers
    who bypass conftest — e.g. IDE integrations)
  - Pins TZ/LANG/PYTHONHASHSEED
  - Uses -n 4 xdist workers (matches GHA ubuntu-latest; -n auto on
    a 20-core workstation surfaces test-ordering flakes CI will never
    see, causing the infamous 'passes in CI, fails locally' drift)
  - Finds the venv in .venv, venv, or main checkout's venv
  - Passes through arbitrary pytest args

Installs pytest-split on demand so the script can also be used to run
matrix-split subsets locally for debugging.

## Remove 3 module-level dotenv stubs that broke test isolation

tests/hermes_cli/test_{arcee,xiaomi,api_key}_provider.py each had a
module-level:

    if 'dotenv' not in sys.modules:
        fake_dotenv = types.ModuleType('dotenv')
        fake_dotenv.load_dotenv = lambda *a, **kw: None
        sys.modules['dotenv'] = fake_dotenv

This patches sys.modules['dotenv'] to a fake at import time with no
teardown. Under pytest-xdist LoadScheduling, whichever worker collected
one of these files first poisoned its sys.modules; subsequent tests in
the same worker that imported load_dotenv transitively (e.g.
test_env_loader.py via hermes_cli.env_loader) got the no-op lambda and
saw their assertions fail.

dotenv is a required dependency (python-dotenv>=1.2.1 in pyproject.toml),
so the defensive stub was never needed. Removed.

## Validation

- tests/hermes_cli/ alone: 2178 passed, 1 skipped, 0 failed (was 4
  failures in test_env_loader.py before this fix)
- tests/test_plugin_skills.py, tests/hermes_cli/test_plugins.py,
  tests/test_hermes_logging.py combined: 123 passed (the caplog
  regression tests from PR NousResearch#11453 still pass)
- Local full run shows no F/E clusters in the 0-55% range that were
  previously present before the conftest hardening

## Background

See AGENTS.md 'Testing' section for the full list of drift sources
this closes. Matrix split (closed as NousResearch#11566) will be re-attempted
once this foundation lands — cross-test pollution was the root cause
of the shard-3 hang in that PR.

* fix(conftest): don't redirect HOME — it broke CI subprocesses

PR NousResearch#11577's autouse fixture was setting HOME to a per-test tempdir.
CI started timing out at 97% complete with dozens of E/F markers and
orphan python processes at cleanup — tests (or transitive deps)
spawn subprocesses that expect a stable HOME, and the redirect broke
them in non-obvious ways.

Env-var unsetting and TZ/LANG/hashseed pinning (the actual CI-drift
fixes) are unchanged and still in place. HERMES_HOME redirection is
also unchanged — that's the canonical way to isolate tests from
~/.hermes/, not HOME.

Any code in the codebase reading ~/.hermes/* via `Path.home() / ".hermes"`
instead of `get_hermes_home()` is a bug to fix at the callsite, not
something to paper over in conftest.