diff --git a/docs/01_run_sequence.md b/docs/01_run_sequence.md
index d6247e6..67c76ea 100644
--- a/docs/01_run_sequence.md
+++ b/docs/01_run_sequence.md
@@ -1,129 +1,315 @@
-# Run Sequence: What Happens When You Start Tests
-
-This document walks through the exact order of operations when you run the framework with pytest, what gets called, and where configuration/data is fetched from.
-
-## High-level flow
-
-1. You run pytest from PowerShell
-2. pytest reads `pytest.ini` and loads configured plugins (including our custom `conftest_plugin`)
-3. Test discovery collects tests under `tests/`
-4. Session fixtures run:
-   - `config()` loads YAML configuration
-   - `lin()` selects and connects the LIN interface (Mock, MUM, or the deprecated BabyLIN)
-   - `flash_ecu()` optionally flashes the ECU (if enabled)
-5. Tests execute using fixtures and call interface methods
-6. Our plugin extracts test metadata (Title, Requirements, Steps) from docstrings
-7. Reports are written to `reports/report.html` and `reports/junit.xml`
-
-## Detailed call sequence
-
-```mermaid
-sequenceDiagram
-  autonumber
-  participant U as User (PowerShell)
-  participant P as pytest
-  participant PI as pytest.ini
-  participant PL as conftest_plugin.py
-  participant T as Test Discovery (tests/*)
-  participant F as Fixtures (conftest.py)
-  participant C as Config Loader (ecu_framework/config.py)
-  participant PS as Power Supply (optional)
-  participant L as LIN Adapter (mock/MUM/BabyLIN)
-  participant X as HexFlasher (optional)
-  participant R as Reports (HTML/JUnit)
-
-  U->>P: python -m pytest [args]
-  P->>PI: Read addopts, markers, plugins
-  P->>PL: Load custom plugin hooks
-  P->>T: Collect tests
-  P->>F: Init session fixtures
-  F->>C: load_config(workspace_root)
-  C-->>F: EcuTestConfig (merged dataclasses)
-  F->>L: Create interface (mock, MUM, or BabyLIN SDK)
-  L-->>F: Instance ready
-  F->>L: connect()
-  alt flash.enabled and hex_path provided
-    F->>X: HexFlasher(lin).flash_hex(hex_path)
-    X-->>F: Flash result (ok/fail)
-  end
-  opt power_supply.enabled and port provided
-    Note over PS: owon_psu_quick_demo may open PSU via ecu_framework.power.owon_psu
-  end
-  loop for each test
-    P->>PL: runtest_makereport(item, call)
-    Note over PL: Parse docstring and attach metadata
-    P->>L: send()/receive()/request()
-    L-->>P: Frames or None (timeout)
-  end
-  P->>R: Write HTML (with metadata columns)
-  P->>R: Write JUnit XML
-```
-
-```text
-PowerShell → python -m pytest
-  ↓
-pytest loads pytest.ini
-  - addopts: --junitxml, --html, --self-contained-html, -p conftest_plugin
-  - markers registered
-  ↓
-pytest collects tests in tests/
-  ↓
-Session fixture: config()
-  → calls ecu_framework.config.load_config(workspace_root)
-    → determines config file path by precedence
-    → merges YAML + overrides into dataclasses (EcuTestConfig)
-    → optionally merges config/owon_psu.yaml (or OWON_PSU_CONFIG) into power_supply
-  ↓
-Session fixture: lin(config)
-  → chooses interface by config.interface.type
-    - mock    → ecu_framework.lin.mock.MockBabyLinInterface(...)
-    - mum     → ecu_framework.lin.mum.MumLinInterface(host, lin_device, power_device, ...)
-    - babylin → ecu_framework.lin.babylin.BabyLinInterface(...)  [DEPRECATED]
-  → lin.connect()
-    - MUM connect() also powers up the ECU via power_out0 and waits boot_settle_seconds
-  ↓
-Optional session fixture: flash_ecu(config, lin)
-  → if config.flash.enabled and hex_path set
-  → ecu_framework.flashing.HexFlasher(lin).flash_hex(hex_path)
-  ↓
-Test functions execute
-  → use the lin fixture to send/receive/request
-  ↓
-Reporting plugin (conftest_plugin.py)
-  → pytest_runtest_makereport parses test docstring
-  → attaches user_properties: title, requirements, steps, expected_result
-  → pytest-html hooks add Title and Requirements columns
-  ↓
-Reports written
-  → reports/report.html (HTML with metadata columns)
-  → reports/junit.xml (JUnit XML for CI)
-```
-
-## Where information is fetched from
-
-- pytest configuration: `pytest.ini`
-- YAML config (default): `config/test_config.yaml`
-- YAML override via env var: `ECU_TESTS_CONFIG`
-- BabyLIN SDK wrapper and SDF path (DEPRECATED): `interface.sdf_path` and `interface.schedule_nr` in YAML
-- Test metadata: parsed from each test’s docstring
-- Markers: declared in `pytest.ini`, attached in tests via `@pytest.mark.*`
-
-## Key components involved
-
-- `tests/conftest.py`: defines `config`, `lin`, and `flash_ecu` fixtures
-- `ecu_framework/config.py`: loads and merges configuration into dataclasses
-- `ecu_framework/lin/base.py`: abstract LIN interface contract and frame shape
-- `ecu_framework/lin/mock.py`: mock behavior for send/receive/request
-- `ecu_framework/lin/mum.py`: MUM adapter (Melexis Universal Master via pylin + pymumclient)
-- `ecu_framework/lin/babylin.py`: BabyLIN SDK wrapper adapter (DEPRECATED real hardware path via BabyLIN_library.py; emits `DeprecationWarning` on use)
-- `ecu_framework/flashing/hex_flasher.py`: placeholder flashing logic
-- `conftest_plugin.py`: report customization and metadata extraction
-
-## Edge cases and behavior
-
-- If `interface.type` is `babylin` (deprecated) but the SDK wrapper or libraries cannot be loaded, hardware tests are skipped
-- If `interface.type` is `mum` but `pylin` / `pymumclient` aren't importable, or `interface.host` is unset, hardware tests are skipped with a clear message
-- If `flash.enabled` is true but `hex_path` is missing, flashing fixture skips
-- Timeouts are honored in `receive()` and `request()` implementations
-- Invalid frame IDs (outside 0x00–0x3F) or data > 8 bytes will raise in `LinFrame`
-- MUM `receive()` is master-driven: it requires a frame ID; `receive(id=None)` raises NotImplementedError. Diagnostic frames needing LIN 1.x Classic checksum should use `MumLinInterface.send_raw()`.
+# Run Sequence: What Happens When You Start Tests
+
+This document walks through the exact order of operations when you run
+the framework with pytest, what gets called, and where
+configuration / data is fetched from. The flow has two layers:
+
+- **Project-wide** fixtures in `tests/conftest.py` — `config`, `lin`,
+  `ldf`, `flash_ecu`, `rp`. Apply to every test.
+- **Hardware-suite** fixtures in `tests/hardware/conftest.py` — a
+  session-scoped, autouse PSU power-up plus the public `psu` fixture.
+  Apply only to tests under `tests/hardware/`.
+
+## High-level flow
+
+1. You run pytest from PowerShell (or any shell).
+2. pytest reads `pytest.ini` (markers, addopts, `junit_family=legacy`)
+   and loads `conftest_plugin` for HTML/metadata enrichment.
+3. Test discovery collects tests under `tests/`.
+4. **Project-wide** session fixtures resolve as needed:
+   - `config()` loads YAML configuration into typed dataclasses.
+   - `lin()` selects and connects the LIN adapter (Mock / MUM /
+     deprecated BabyLIN).
+   - `ldf()` loads the LDF database (when `interface.ldf_path` is set).
+   - `flash_ecu()` optionally flashes the ECU.
+5. **For hardware tests only**, the session-scoped autouse fixture
+   `_psu_powers_bench` realizes `_psu_or_none`, which:
+   - Opens the Owon PSU once via the cross-platform `resolve_port()`,
+   - Parks it at `config.power_supply.set_voltage` /
+     `set_current`,
+   - Enables output and leaves it on for the entire session.
+   This keeps the ECU powered for every test in the suite — even
+   tests that don't request `psu` by name.
+6. Per-test bodies execute — typically through the helper layer
+   (`FrameIO`, `AlmTester`, `apply_voltage_and_settle`) rather than
+   raw `lin.send()` / `lin.receive()`.
+7. The `conftest_plugin` parses each test's docstring (Title /
+   Description / Requirements / Steps / Expected Result) and attaches
+   the values as JUnit `<property>` entries.
+8. At session end the PSU's `safe_off_on_close` sends `output 0`
+   before releasing the port; reports are written.
+
+## Detailed call sequence (Mermaid)
+
+```mermaid
+sequenceDiagram
+  autonumber
+  participant U  as User (shell)
+  participant P  as pytest
+  participant PI as pytest.ini
+  participant PL as conftest_plugin.py
+  participant T  as Test discovery (tests/*)
+  participant CF as tests/conftest.py
+  participant HCF as tests/hardware/conftest.py
+  participant C  as Config Loader
+  participant L  as LIN Adapter (mock/MUM/BabyLIN)
+  participant LD as LDF Database
+  participant PSU as PSU (session-scoped)
+  participant FH as Helper layer (FrameIO/AlmTester/psu_helpers)
+  participant X  as HexFlasher (optional)
+  participant R  as Reports (HTML/JUnit/Summary)
+
+  U->>P: python -m pytest [args]
+  P->>PI: addopts, markers, junit_family=legacy
+  P->>PL: Register custom plugin hooks
+  P->>T: Collect tests
+
+  rect rgba(200,220,255,0.25)
+    Note over CF: Project-wide fixtures (every test)
+    P->>CF: Resolve session fixtures
+    CF->>C: load_config(workspace_root)
+    C-->>CF: EcuTestConfig
+    CF->>L: Create interface (per interface.type)
+    CF->>L: lin.connect()
+    L-->>CF: ready (MUM also powers ECU via power_out0)
+    opt interface.ldf_path set
+      CF->>LD: LdfDatabase(ldf_path)
+    end
+  end
+
+  rect rgba(220,255,220,0.30)
+    Note over HCF: Hardware-suite fixtures (tests/hardware/*)
+    P->>HCF: Realize _psu_powers_bench (autouse, session)
+    HCF->>PSU: resolve_port + open + set V/I + output ON
+    PSU-->>HCF: powered, leave on for session
+  end
+
+  alt flash.enabled and hex_path provided
+    CF->>X: HexFlasher(lin).flash_hex(hex_path)
+    X-->>CF: ok / fail
+  end
+
+  loop for each test (function scope)
+    P->>FH: Test body uses FrameIO.send/receive/read_signal,
+    Note over FH: AlmTester.* and/or apply_voltage_and_settle
+    FH->>L: send() / receive()
+    L-->>FH: Frames / None
+    FH->>PSU: set_voltage() + measure_voltage_v() (voltage tests)
+    PSU-->>FH: settled value
+    P->>PL: pytest_runtest_makereport(item, call)
+    Note over PL: Parse docstring → user_properties
+  end
+
+  P->>R: HTML report with metadata columns
+  P->>R: JUnit XML (junit_family=legacy → record_property entries)
+  P->>R: summary.md, requirements_coverage.json
+
+  rect rgba(255,220,220,0.30)
+    Note over PSU: Session teardown
+    HCF->>PSU: close() → safe_off_on_close sends 'output 0'
+  end
+```
+
+## Text flow (project-wide + hardware-suite layers)
+
+```text
+shell → python -m pytest
+  ↓
+pytest loads pytest.ini
+  - addopts: -ra --junitxml=… --html=… --tb=short --cov=…
+  - junit_family = legacy   ← required for record_property() round-trip
+  - markers registered (hardware, mum, babylin (deprecated),
+                        slow, psu_settling, smoke, …)
+  ↓
+pytest collects tests in tests/
+  ↓
+─────────────────────────────────────────────────────────────────────
+PROJECT-WIDE fixtures (tests/conftest.py)  — apply to every test
+─────────────────────────────────────────────────────────────────────
+Session: config()
+  → ecu_framework.config.load_config(workspace_root)
+    → precedence: in-memory overrides > ECU_TESTS_CONFIG env >
+                  ./config/test_config.yaml > defaults
+    → optionally merges config/owon_psu.yaml (or OWON_PSU_CONFIG)
+      into power_supply
+  → returns EcuTestConfig (typed dataclasses)
+
+Session: lin(config)
+  → chooses adapter by interface.type:
+      mock    → ecu_framework.lin.mock.MockBabyLinInterface(...)
+      mum     → ecu_framework.lin.mum.MumLinInterface(host, lin_device,
+                                                      power_device, …)
+      babylin → ecu_framework.lin.babylin.BabyLinInterface(...) [DEPRECATED]
+  → lin.connect()
+    - MUM also powers the ECU via power_out0 and waits
+      boot_settle_seconds before sending the first frame
+
+Session: ldf(config)
+  → if interface.ldf_path set: LdfDatabase(ldf_path)
+  → else: skip (tests requesting `ldf` are skipped with a clear msg)
+
+Session (opt): flash_ecu(config, lin)
+  → if flash.enabled and flash.hex_path set
+  → HexFlasher(lin).flash_hex(hex_path)
+
+Function: rp(record_property)
+  → convenience wrapper that records both as a JUnit property AND
+    echoes to captured stdout for fast diagnosis
+
+─────────────────────────────────────────────────────────────────────
+HARDWARE-SUITE fixtures (tests/hardware/conftest.py) — only for
+tests under tests/hardware/
+─────────────────────────────────────────────────────────────────────
+Session: _psu_or_none(config)
+  → if power_supply disabled / port unset / unreachable:
+      yield None (tolerant; does not raise)
+  → else:
+      params  = SerialParams.from_config(power_supply)
+      port    = resolve_port(power_supply.port,
+                             idn_substr=power_supply.idn_substr,
+                             params=params)
+        ↑ tries the configured port verbatim, then its
+          cross-platform translation (COM7 ↔ /dev/ttyS6 on WSL1),
+          then /dev/ttyUSB* / /dev/ttyACM* on Linux/WSL,
+          then a full scan_ports() with optional idn_substr filter
+      psu     = OwonPSU(port, params, eol, safe_off_on_close=True)
+      psu.open()
+      psu.set_voltage(set_voltage)
+      psu.set_current(set_current)
+      psu.set_output(True)         ← bench powered ON for session
+      yield psu
+      psu.close()                  ← end of session: 'output 0' first
+
+Session, autouse: _psu_powers_bench(_psu_or_none)
+  → realizes _psu_or_none so the bench is powered up even for
+    tests that don't request `psu` by name (no-op if PSU absent)
+
+Session: psu(_psu_or_none)
+  → public alias: skip cleanly if PSU is unavailable
+
+─────────────────────────────────────────────────────────────────────
+TEST BODIES — typically use the helper layer, not lin/psu directly
+─────────────────────────────────────────────────────────────────────
+Hardware-test helpers (sibling-imported from tests/hardware/):
+
+  frame_io.FrameIO(lin, ldf)
+    high  : send / receive / read_signal     (by frame and signal name)
+    mid   : pack / unpack                    (bytes ↔ signals)
+    low   : send_raw / receive_raw           (bypass LDF entirely)
+    intro : frame, frame_id, frame_length
+
+  alm_helpers.AlmTester(fio, nad)
+    force_off, read_led_state, wait_for_state,
+    measure_animating_window,
+    assert_pwm_matches_rgb,           ← uses vendor/rgb_to_pwm.py
+    assert_pwm_wo_comp_matches_rgb
+
+  psu_helpers
+    wait_until_settled(psu, target_v, *, tol, interval, timeout)
+    apply_voltage_and_settle(psu, target_v, *, validation_time, …)
+        1. psu.set_voltage(target_v)
+        2. poll measure_voltage_v() until within tol (or raise)
+        3. sleep validation_time so the firmware-side observer
+           can detect and republish status
+        → returns {settled_s, validation_s, final_v, trace}
+
+Per-file autouse fixtures often layer on a domain baseline:
+
+  test_mum_alm_animation.py:_reset_to_off       → alm.force_off()
+  test_overvolt.py:_park_at_nominal             → apply_voltage_and_settle(NOMINAL_V) + force_off
+  _test_case_template_psu_lin.py:_park_at_nominal → same pattern
+
+Reporting plugin (conftest_plugin.py)
+  → pytest_runtest_makereport parses docstring (Title / Description /
+    Requirements / Test Steps / Expected Result)
+  → attaches user_properties; pytest-html shows Title + Requirements
+    columns; junit_family=legacy ensures record_property() round-trips
+
+Reports written
+  → reports/report.html              (HTML with metadata columns)
+  → reports/junit.xml                (JUnit XML — properties round-trip)
+  → reports/summary.md               (machine-friendly run summary)
+  → reports/requirements_coverage.json
+```
+
+## Where information is fetched from
+
+- pytest configuration: `pytest.ini` (markers, addopts,
+  `junit_family = legacy`)
+- YAML config (default): `config/test_config.yaml`
+- YAML override via env var: `ECU_TESTS_CONFIG`
+- Per-machine PSU override: `config/owon_psu.yaml` (or
+  `OWON_PSU_CONFIG`); merged into `power_supply`
+- LDF database: `interface.ldf_path` (typically
+  `vendor/4SEVEN_color_lib_test.ldf`); consumed by the `ldf` fixture
+  and by `FrameIO`
+- RGB→PWM calculator: `vendor/rgb_to_pwm.py`; consumed by
+  `AlmTester.assert_pwm_*`
+- BabyLIN SDF / schedule (DEPRECATED): `interface.sdf_path` and
+  `interface.schedule_nr`
+- Test metadata: parsed from each test's docstring
+- Markers: declared in `pytest.ini`, attached in tests via
+  `@pytest.mark.*` (file-level via `pytestmark = [...]`)
+
+## Key components involved
+
+### Project-wide
+
+- `tests/conftest.py` — defines `config`, `lin`, `ldf`, `flash_ecu`, `rp`
+- `conftest_plugin.py` — report customization and metadata extraction
+- `ecu_framework/config.py` — YAML → dataclasses
+- `ecu_framework/lin/{base,mock,mum,ldf,babylin}.py` — LIN abstraction
+  and adapters
+- `ecu_framework/flashing/hex_flasher.py` — flashing scaffold
+- `ecu_framework/power/owon_psu.py` — PSU controller +
+  `resolve_port()`
+
+### Hardware-suite (`tests/hardware/`)
+
+- `conftest.py` — session-scoped autouse PSU fixture (powers the ECU
+  for the entire session)
+- `frame_io.py` — `FrameIO` class (generic LDF-driven I/O)
+- `alm_helpers.py` — `AlmTester` class + ALM constants and tolerance
+  utilities
+- `psu_helpers.py` — `wait_until_settled` /
+  `apply_voltage_and_settle` (settle-then-validate pattern)
+- `_test_case_template.py`, `_test_case_template_psu_lin.py` —
+  copyable starting points (leading underscore → not collected)
+
+## Edge cases and behaviour
+
+### LIN side
+
+- `interface.type == 'babylin'` (deprecated): if the SDK wrapper or
+  libraries can't load, hardware tests skip cleanly.
+- `interface.type == 'mum'`: if `pylin` / `pymumclient` aren't
+  importable, or `interface.host` is unset, hardware tests skip.
+- MUM `receive()` is master-driven: it requires a frame ID;
+  `receive(id=None)` raises `NotImplementedError`. Diagnostic frames
+  needing LIN 1.x Classic checksum must go through
+  `MumLinInterface.send_raw()`.
+- `flash.enabled == true` but `hex_path` missing → flashing fixture
+  skips.
+- Invalid frame IDs (outside 0x00–0x3F) or data > 8 bytes raise in
+  `LinFrame`.
+
+### PSU / hardware side
+
+- PSU port resolution: if the configured port can't be opened on this
+  host (e.g. `COM7` on Linux), `resolve_port()` falls back to its
+  cross-platform translation (`COM7` → `/dev/ttyS6` on WSL1), then
+  `/dev/ttyUSB*` / `/dev/ttyACM*`, then a full scan filtered by
+  `idn_substr`. Returns `None` if nothing responds — the `psu`
+  fixture then skips cleanly.
+- The session-scoped PSU fixture **must not** be closed mid-session.
+  Tests that perturb voltage **must restore nominal in `finally`**;
+  they **must not** call `psu.set_output(False)` (would brown out the
+  ECU and break every later test).
+- `apply_voltage_and_settle()` raises `AssertionError` if the rail
+  doesn't reach the target within `settle_timeout` (default 10 s) —
+  surfacing real bench problems rather than letting voltage tests
+  silently assert against the wrong rail.
+- `record_property()` / `rp(...)` entries only appear in
+  `reports/junit.xml` when `junit_family = legacy` is set in
+  `pytest.ini` (default `xunit2` silently drops them with a
+  collect-time warning).