Add USB camera and uhubctl support for new test suite. Also included some bug fixes (#10204)

* Add USB camera and uhubctl support for new test suite. Also added some bug fixes

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Refactor test messages for clarity and consistency in regex tests

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

mcp-server/tests/ui/_screen_log.py

@@ -0,0 +1,176 @@
+"""Parse `Screen: frame N/M name=X reason=Y` log lines from `_debug_log_buffer`.
+
+The firmware emits one line per frame transition when
+`USERPREFS_UI_TEST_LOG` is defined (see src/graphics/Screen.cpp). Tests use
+these helpers to assert which frame is shown / to wait for a transition to
+settle before taking a camera capture.
+"""
+
+from __future__ import annotations
+
+import re
+import time
+from dataclasses import dataclass
+from typing import Iterable, Iterator
+
+FRAME_RE = re.compile(
+    r"Screen: frame (?P<idx>\d+)/(?P<count>\d+) name=(?P<name>\S+) reason=(?P<reason>\S+)"
+)
+
+
+@dataclass(frozen=True)
+class FrameEvent:
+    idx: int
+    count: int
+    name: str
+    reason: str
+    raw: str
+
+    @classmethod
+    def parse(cls, line: str) -> "FrameEvent | None":
+        m = FRAME_RE.search(line)
+        if not m:
+            return None
+        return cls(
+            idx=int(m["idx"]),
+            count=int(m["count"]),
+            name=m["name"],
+            reason=m["reason"],
+            raw=line,
+        )
+
+
+def iter_frame_events(lines: Iterable[str]) -> Iterator[FrameEvent]:
+    for line in lines:
+        evt = FrameEvent.parse(line)
+        if evt is not None:
+            yield evt
+
+
+def get_current_frame(lines: list[str]) -> FrameEvent | None:
+    """Return the most recent FrameEvent in `lines`, or None if none found."""
+    for line in reversed(lines):
+        evt = FrameEvent.parse(line)
+        if evt is not None:
+            return evt
+    return None
+
+
+def wait_for_frame(
+    lines: list[str],
+    expected_name: str,
+    *,
+    timeout_s: float = 5.0,
+    poll_interval_s: float = 0.1,
+    reason: str | None = None,
+) -> FrameEvent:
+    """Poll `lines` (the `_debug_log_buffer`) until a FrameEvent with
+    `name=expected_name` appears after the call started. Raises TimeoutError
+    with context if it doesn't arrive in `timeout_s`.
+
+    `reason` optionally filters to events matching a specific cause
+    (e.g. `"fn_f1"`, `"next"`, `"rebuild"`).
+    """
+    start_idx = len(lines)
+    deadline = time.monotonic() + timeout_s
+    last: FrameEvent | None = None
+    while time.monotonic() < deadline:
+        # Scan only lines appended since we started waiting.
+        for line in lines[start_idx:]:
+            evt = FrameEvent.parse(line)
+            if evt is None:
+                continue
+            last = evt
+            if evt.name == expected_name and (reason is None or evt.reason == reason):
+                return evt
+        time.sleep(poll_interval_s)
+
+    seen = [e.name for e in iter_frame_events(lines[start_idx:])]
+    raise TimeoutError(
+        f"frame name={expected_name!r} reason={reason!r} not seen in {timeout_s}s; "
+        f"saw {len(seen)} transition(s): {seen!r}; last={last!r}"
+    )
+
+
+def wait_for_any_frame(
+    lines: list[str],
+    *,
+    timeout_s: float = 5.0,
+    poll_interval_s: float = 0.1,
+) -> FrameEvent:
+    """Wait for ANY frame transition to appear after call-start. Useful for
+    `no-op` tests that want to confirm a transition did NOT happen (via
+    TimeoutError) vs. one that did.
+    """
+    start_idx = len(lines)
+    deadline = time.monotonic() + timeout_s
+    while time.monotonic() < deadline:
+        for line in lines[start_idx:]:
+            evt = FrameEvent.parse(line)
+            if evt is not None:
+                return evt
+        time.sleep(poll_interval_s)
+    raise TimeoutError(f"no frame transition in {timeout_s}s")
+
+
+def wait_for_reason(
+    lines: list[str],
+    reason: str,
+    *,
+    timeout_s: float = 5.0,
+    poll_interval_s: float = 0.1,
+) -> FrameEvent:
+    """Wait for a frame event with `reason=<reason>` after call-start.
+
+    Matches only on `reason` — useful when the caller knows *why* a
+    transition should happen (e.g. `fn_f1`, `rebuild`) but not which named
+    frame the firmware will land on for this particular board.
+    """
+    start_idx = len(lines)
+    deadline = time.monotonic() + timeout_s
+    last: FrameEvent | None = None
+    while time.monotonic() < deadline:
+        for line in lines[start_idx:]:
+            evt = FrameEvent.parse(line)
+            if evt is None:
+                continue
+            last = evt
+            if evt.reason == reason:
+                return evt
+        time.sleep(poll_interval_s)
+    raise TimeoutError(
+        f"no frame with reason={reason!r} in {timeout_s}s; last={last!r}"
+    )
+
+
+def assert_no_frame_change(
+    lines: list[str],
+    *,
+    wait_s: float = 2.0,
+) -> None:
+    """Assert that NO new FrameEvent lines arrive within `wait_s`.
+
+    Used by idempotency / no-op tests (e.g. BACK on home frame).
+    """
+    start_idx = len(lines)
+    time.sleep(wait_s)
+    new = [
+        e for e in (FrameEvent.parse(ln) for ln in lines[start_idx:]) if e is not None
+    ]
+    if new:
+        raise AssertionError(
+            f"expected no frame change in {wait_s}s, but saw {len(new)} event(s): "
+            f"{[(e.reason, e.name) for e in new]!r}"
+        )
+
+
+__all__ = [
+    "FRAME_RE",
+    "FrameEvent",
+    "assert_no_frame_change",
+    "get_current_frame",
+    "iter_frame_events",
+    "wait_for_any_frame",
+    "wait_for_frame",
+    "wait_for_reason",
+]