Files
MeshTerm/meshterm/platforms.py
T
Jean-Pierre MartineauandClaude Opus 5.5 3333201df8 MeshTerm starts from the Cardputer Zero's launcher, on its own battery
Tried on a real Cardputer Zero for the first time. It draws on the
panel, takes the keyboard, and opens from M5's app launcher:
scripts/cardputer-zero/launcher-entry.sh puts a source checkout there
(and `remove` takes it off) until there is a store package.

Three things the hardware showed:

- The splash opened with the highlight on /dev/ttyS0, the Cap's GPS
  UART, because serial is listed first as found. Below the companions
  we've used, anything that looks like one now comes before a port
  nothing vouches for, across transports.
- The title bar's battery is the handheld's own BQ27220, as the
  PicoCalc's is. The host pack is now found by what it is (a Battery
  supply that isn't a peripheral's), not by the PicoCalc's name.
- While the Cap is powered, I2C bus 1 turns noisy: a quarter to three
  quarters of the gauge's reads fail with an I/O error (one in ten of
  the clock's), none with the header off. A failed read is asked again,
  a status that won't read keeps its last verdict, and a good reading
  stands through six failed polls instead of blinking out.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-10-05 16:00:13 -04:00

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# SPDX-License-Identifier: Apache-2.0
"""The platform seam: a frozen spec every consumer binds to once, at boot.
MeshTerm runs its flavours from one codebase — the regular desktop terminal, the
PicoCalc's 53-column framebuffer console, and the Cardputer Zero's 53×14 panel — with no
forked screens and no runtime layer.
A :class:`Platform` is resolved once, at process start, and held in a module-level
singleton; everything downstream (the theme, the frame compositor, the header, the
session's width handling) reads it at *its own* construction/call time and binds its
behaviour accordingly, so the render loop itself never branches on platform.
Read the active platform through :func:`get_platform` (or the module-qualified
``platforms.PLATFORM``) — never ``from meshterm.platforms import PLATFORM`` at a
module's top level. That statement runs once, at import time, and copies whatever
:data:`PLATFORM` pointed to *then*; :func:`set_platform` rebinding the module global
afterwards would never reach that stale copy. A function call always re-reads the
current value, so it has no such trap.
"""
from __future__ import annotations
import os
from collections.abc import Callable, Iterator
from contextlib import contextmanager
from dataclasses import dataclass, replace
from pathlib import Path
@dataclass(frozen=True, slots=True)
class Platform:
"""One flavour's complete rendering/behaviour spec.
Every field is data a consumer binds to at its own construction/call time (see the
module docstring) — there is no code path that branches on ``platform.name`` itself
outside this module and the small set of binding points documented at each field.
Attributes:
name: Stable identifier — ``"regular"``, ``"picocalc-lyra"`` or ``"cardputer-zero"``
— used for ``--platform``/``MESHTERM_PLATFORM`` matching and diagnostics. A
handheld's is its product and the variant that sets it apart from its siblings:
M5Stack makes three Cardputers and only the Zero runs Linux, and the PicoCalc
takes several cores and only the Luckfox Lyra runs MeshTerm.
readable_cols: The readability standard (CLAUDE.md's "screens stay readable at
N columns") and the dual-platform gallery's test width.
readable_rows: The row *floor* a screen designs to. PicoCalc's live console is
53×26 (custom 6×12 font); a 6×8 font rebuild (P5) gives 53×40. Screens design
to this floor and exploit extra rows fluidly; the gallery renders picocalc-lyra at
both 26 and 40 rows.
frame_border: Whether the base screen draws inside a bordered ``Panel``. ``False``
swaps it for a title-bar row instead (+4 cols, +1 row reclaimed) — a PicoCalc
chrome saving, wired in P4.
menu_icons: Whether a *command row* leads with a decorative icon — the main menu's
per-tool mark, an action list's ``🗑``/``🕒``, a body action's ``✎``. The label
already names the action, so the icon is a family cue, not information; where
the console can only spell it as a one-glyph stand-in the cue is worth less
than the cells it costs and reads as noise besides (``@`` for both Map and
Mesh walk, ``…`` for both Live feed and Time machine — JP, on-device,
2026-08-11). ``False`` drops the whole lane, mark and emoji alike, and the
cells go to the label and its description. This is about *decoration* only:
a glyph that carries data — a channel's openness, a packet's class, a node's
type, a status mark on an outcome — is not a menu icon and is never dropped
(see :func:`~meshterm.ui.menus.command_label`).
dialog_margin: Total columns a floating dialog leaves to the backdrop it sits over
— half of it on each side (see
:func:`~meshterm.ui.tui.frame._dialog_layout`). The gutter is what makes a
dialog read as floating rather than as a new screen, and three columns a side
do that comfortably at 72. On the 53-column console the *same* gutter is a
twelfth of the whole display, and it costs content: a packet card's reception
row folds ``rssi`` onto a line of its own for want of two cells (JP, on-device,
2026-08-10). Two columns a side still reads as floating and buys them back.
dialog_row_margin: Rows a floating dialog leaves to the frame around it — the header
above and the footer below, plus any blank row between them and the box. One row
of air above and below is what lets a box read as floating on a 24-row terminal
(4 in all). On the Cardputer's 14 rows every row a dialog gives up is a row it
can't show, its side gutters already say it floats, and there is no header row
above the title bar, so a tall box runs from the top row to the lane (1),
drawing over the bar — whose ends either side of the box are blanked rather than
left as fragments (see :func:`~meshterm.ui.tui.frame.composite_float`). Never
over the lane: a dialog's lane is the dialog's own, and the keys on it are named
nowhere else.
header_atoms: Which segments compose the persistent header, in the vocabulary
``"version"``, ``"device"``, ``"badges"``, ``"pulse"``, ``"battery"``. Wired
into :func:`~meshterm.ui.menu._header` in P4; unconsumed until then.
header_row: Whether the persistent header has a row of its own above the frame.
Where it doesn't (the Cardputer, JP 2026-10-03), the header's atoms ride the
borderless title bar's right end, after the way out — so its badges and battery
sit in the top-right corner they always had, one row up, and every screen gets
that row back — and the wordmark becomes the main menu's title (see
:func:`~meshterm.ui.menu._menu_title`). Only a borderless frame can fold it: the
bordered panel has no bar to carry it.
lane_deck: Which F-key lane deck the footer deals, by name (see
:data:`~meshterm.ui.tui.fkeys.DECKS`), or ``""`` where the footer is each
screen's own ``footer_hint`` string instead. A deck is everything about the lane
that belongs to one keyboard: which keycodes drive its slots, where its chips sit
on the row, how they are drawn, and which of a screen's lane definitions it reads
(``Screen.picocalc_lyra_lane``, ``Screen.cardputer_zero_lane``). Each handheld names its
own, so one can change without the other following. :attr:`footer_fkeys` is the
yes/no reading of it.
width_reclaim: Whether the session may report one extra terminal column (see
:class:`~meshterm.ui.tui.session._WidthExtendedOutput`). ``True`` only *lets*
it: the column is reclaimed where the terminal's size probe hid one, which is
prompt_toolkit's Windows console output and nothing else
(:func:`~meshterm.ui.tui.session._probe_hides_last_column`). ``False`` on
PicoCalc's exact-width console, where a phantom extra column tears the frame.
``MESHTERM_FULL_WIDTH`` remains an explicit override on top of this default.
emoji: Whether emoji icons render at all. ``False`` means every icon funnel routes
through a compact single-BMP-glyph table instead (P3), and neither half of the
emoji alignment runs — the reserve-two measurement
(:func:`~meshterm.ui.tui.emoji_width.install`) or the column pinning
(:mod:`~meshterm.ui.tui.colsnap`). Once no emoji are ever drawn, every glyph on
screen is one the console font has verified, and the stock widths are exact.
font: The glyph inventory the screen is drawn in, by name (see
:data:`~meshterm.ui.fontset.FONTS`), or ``""`` where a terminal draws whatever
it is sent. A handheld's every frame is folded down to its font at the render
boundary (:func:`~meshterm.ui.theme.fold_text`) — an accent the font lacks
stripped, an emoji turned to its compact glyph, anything else still missing a
narrow ``?`` — so nothing the panel can't draw is ever sent to it. Storage is
never touched.
truecolor: Whether the theme may use arbitrary 24-bit SGR colour. ``False`` selects
a 16-slot palette theme instead (the console's real ceiling — no per-cell RGB),
and quantizes the two scales that would otherwise spend a gradient — the
per-node key hue (:func:`~meshterm.ui.theme.node_style`) and the heard-age heat
(:func:`~meshterm.ui.widgets._recency_style`). Wired in P3.
solid_braille: Whether the console font draws a braille cell's eight dots as solid
tiles with no gap between them or between neighbouring cells — the PicoCalc's
built fonts (``scripts/picocalc-lyra``) do — so braille is a true 2×4 pixel grid,
fine enough for what must stay contiguous. It is what lets every QR code be
drawn in braille, one module a dot (:mod:`~meshterm.ui.qr`). A desktop font's
braille is dotted, and a code drawn in it scans as nothing.
url_codes: Whether a chat message's URLs are drawn as QR codes under it, side by
side (:meth:`~meshterm.ui.chat.ChatScreen._body_lines`) — so a link read on the
handheld opens on a phone without being typed out. The PicoCalc's alone: it
takes braille codes (:attr:`solid_braille`) to be small enough to sit in a
transcript at all, a quarter the area of the half blocks a desktop draws, and
it takes rows — a short link's code is 9 of them, which the Cardputer's 14
cannot spare under every message that carries one (JP, 2026-10-01).
effects: Whether animated/decorative rendering runs at all — the braille spinner,
which drops to a ``LINE`` fallback. Cheaper on a console where a repaint is
dear. The header battery gauge is deliberately *not* behind it: its sweep is
the charging state itself and its blink is the last warning before the pack
dies, and both ride the idle repaint that happens anyway. Wired in P2/P3.
tick_s: The :class:`~prompt_toolkit.application.Application` refresh interval — the
*idle* repaint cadence only, since every screen pushes its own repaint through
``TuiSession.invalidate`` when its data actually moves. Composing one frame was
measured at 74 ms on the PicoCalc at 53×26 (110 ms at 53×40), so a 1 Hz idle
tick alone costs 7–11% of a core doing nothing; it ticks at half that rate
there. What drifts is cosmetic — the header's per-minute pulse and its packet
counter — and none of it is legible at one-second resolution anyway.
spinner_tick_s: Seconds between frames of a "working" spinner. The single source for
every animated wait in the app. The desktop's 0.12 s is not a rate this hardware
can hold: a PicoCalc frame would claim 62% of a core at 53×26, and at 53×40 its
110 ms of compose would leave under 10 ms of each interval for the work actually
being waited on — and before this phase's savings it did not fit at all, at
152 ms against a 120 ms budget. It slows to a cadence the hardware can hold
comfortably while still reading as alive.
battery: Which source feeds the header's battery gauge — ``"companion"`` (read
from the connected MeshCore device) or ``"host"`` (the PicoCalc's own sysfs
``power_supply`` driver, confirmed present in P0). Wired in P5.
own_display: Whether MeshTerm draws this display itself (:mod:`meshterm.emulator`)
rather than running in a terminal — where the app is its own terminal, nothing
about the one it was started from (a classic Windows console to move out of, a
font to offer) is its business. True on the Cardputer Zero, whose launcher gives
an app no console; and for any platform while the emulator shows it in a window.
modifier_watch: The keyboard whose Shift state the optional evdev watcher follows,
flipping the displayed F-key lane live while Shift is held — a case-insensitive
substring of the input device's name, or ``""`` to leave the watcher off.
Handhelds only: desktop terminals have no lane to flip, and the watcher needs
``/dev/input`` access a handheld's deploy user has (the ``input`` group). Always
optional and lazy; wired in P4.
"""
name: str
readable_cols: int
readable_rows: int
frame_border: bool
menu_icons: bool
dialog_margin: int
dialog_row_margin: int
header_atoms: tuple[str, ...]
header_row: bool
lane_deck: str
width_reclaim: bool
emoji: bool
font: str
truecolor: bool
solid_braille: bool
url_codes: bool
effects: bool
tick_s: float
spinner_tick_s: float
battery: str
own_display: bool
modifier_watch: str
@property
def footer_fkeys(self) -> bool:
"""Whether the footer is an F-key lane rather than each screen's hint string."""
return bool(self.lane_deck)
#: Exactly today's behaviour — the desktop/ssh terminal, unchanged by this seam's arrival.
REGULAR = Platform(
name="regular",
readable_cols=72,
readable_rows=24,
frame_border=True,
menu_icons=True,
dialog_margin=6,
dialog_row_margin=4,
header_atoms=("version", "device", "badges", "pulse", "battery"),
header_row=True,
lane_deck="",
width_reclaim=True,
emoji=True,
font="",
truecolor=True,
solid_braille=False,
url_codes=False,
effects=True,
tick_s=1.0,
spinner_tick_s=0.12,
battery="companion",
own_display=False,
modifier_watch="",
)
#: The PicoCalc/Lyra/Calculinux framebuffer console. Field values not yet consumed by a
#: binding point (header_atoms, font, truecolor, effects beyond the
#: two P1 bindings, tick_s, battery, modifier_watch) are P2–P5's targets, recorded here
#: now so the seam exists before the flavour work lands.
PICOCALC_LYRA = Platform(
name="picocalc-lyra",
readable_cols=53,
readable_rows=26,
frame_border=False,
menu_icons=False,
dialog_margin=4,
dialog_row_margin=4,
# JP's call (2026-08-01, post-P7 review): the handheld's header brands the app —
# "MeshTerm vX" — rather than naming the device/port (on a soldered radio the port
# never changes), and the activity pulse takes whatever room remains.
header_atoms=("version", "badges", "pulse", "battery"),
header_row=True,
lane_deck="picocalc-lyra",
width_reclaim=False,
emoji=False,
font="picocalc-lyra",
truecolor=False,
solid_braille=True,
url_codes=True,
effects=False,
tick_s=2.0,
spinner_tick_s=0.5,
battery="host",
own_display=False,
modifier_watch="picocalc",
)
#: M5Stack's Cardputer Zero: a 320×170 panel drawn in 6×12 cells (53×14), under a
#: 46-key keyboard whose number keys 4–8 sit right below the display. Hardware not yet in
#: hand (2026-10-04), so this is chosen by ``--platform cardputer-zero`` / ``MESHTERM_PLATFORM``
#: only — no device-tree auto-detection until the device reports its own model string.
#:
#: The same 53 columns as the PicoCalc, which is why most of its flavour carries over; the
#: new constraint is rows. It has its own F-key lane deck (Fn+4…8, chips centred over their
#: keys), dealing the PicoCalc's lanes for now (JP, 2026-09-30). MeshTerm draws the panel
#: itself in RGB565 (:mod:`meshterm.emulator`), so it is not held to a 16-slot palette
#: (``truecolor``). Provisional until measured on the device: the cadences, taken from the
#: PicoCalc; and ``effects`` off. The battery is the handheld's own BQ27220 gauge, which the
#: kernel publishes as the ``power_supply`` ``bq27220-0`` (seen on the device, 2026-10-05) —
#: the pack the reader is holding, whichever radio is connected, as on the PicoCalc.
CARDPUTER_ZERO = Platform(
name="cardputer-zero",
readable_cols=53,
readable_rows=14,
frame_border=False,
menu_icons=False,
dialog_margin=4,
dialog_row_margin=1,
# No header row (JP, 2026-10-03): the badges and battery ride the title bar's right
# end, the wordmark is the main menu's title, and the pulse, which only ever had the
# header's leftover cells, goes — the dashboard draws the mesh's activity in full.
header_atoms=("badges", "battery"),
header_row=False,
lane_deck="cardputer-zero",
width_reclaim=False,
emoji=False,
font="cardputer-zero",
truecolor=True,
# The emulator draws its own braille, as the PicoCalc's built fonts do: solid
# tiles, no gap between dots (meshterm/emulator/font.py, BRAILLE).
solid_braille=True,
url_codes=False,
effects=False,
tick_s=2.0,
spinner_tick_s=0.5,
battery="host",
own_display=True,
modifier_watch="tca8418c",
)
_BY_NAME = {p.name: p for p in (REGULAR, PICOCALC_LYRA, CARDPUTER_ZERO)}
#: The active platform. Do not import this name directly (see the module docstring) —
#: read it through :func:`get_platform`, and change it only through :func:`set_platform`.
PLATFORM = REGULAR
def get_platform() -> Platform:
"""Return the active :class:`Platform`.
Safe to call from anywhere, at any time — always reflects the most recent
:func:`set_platform` call, however that module was imported.
"""
return PLATFORM
#: Callbacks re-run on every :func:`set_platform`, so a module can bind platform-derived
#: state (a chosen theme, a swapped function implementation) once per *switch* instead of
#: re-deriving it per call in a render loop. Registered via :func:`on_platform`.
_BINDINGS: list[Callable[[Platform], None]] = []
def on_platform(binding: Callable[[Platform], None]) -> Callable[[Platform], None]:
"""Register (and immediately run) a platform binding.
The seam's principle is *bind at construction time, never per frame*: a consumer that
must swap behaviour with the platform (the theme's ``name_style`` impl, the
rasterizer's console cache) registers a binding here at its own import time. The
binding runs once right away — against the platform active *now* — and again on every
later :func:`set_platform`, so tests that swap platforms rebind automatically and the
consumer's hot path reads a plain module global.
Args:
binding: Called with the active :class:`Platform`; must be idempotent.
Returns:
``binding`` unchanged, so it can be used as a decorator.
"""
_BINDINGS.append(binding)
binding(PLATFORM)
return binding
def set_platform(platform: Platform) -> None:
"""Install ``platform`` as the active one and re-run every registered binding.
Called exactly once by the CLI callback, before :func:`~meshterm.ui.theme.make_console`
— every other read of :func:`get_platform` in the same process happens after this.
Idempotent (setting the same platform twice is a no-op in effect) and reversible, so
tests can swap in a platform for one test and restore the previous one afterwards
(see the ``_reset_platform`` autouse fixture in ``tests/conftest.py``).
Args:
platform: The platform to make active.
"""
global PLATFORM
PLATFORM = platform
for binding in _BINDINGS:
binding(platform)
@dataclass(frozen=True, slots=True)
class Resolution:
"""What :func:`resolve` looked at and what it landed on.
Exists so the ``meshterm platform`` diagnostic can report every input the resolution
considered, not just the final answer.
Attributes:
flag: The ``--platform`` value passed on the command line, if any.
env: The ``MESHTERM_PLATFORM`` environment variable's value, if set.
detected_model: The ``/proc/device-tree/model`` contents read during resolution
(trailing NUL/space stripped), or ``None`` when the file doesn't exist (every
non-Lyra machine, including every desktop and CI runner).
source: Which input decided the outcome — ``"--platform flag"``,
``"MESHTERM_PLATFORM env var"``, ``"auto-detect"``, or ``"default"``.
platform: The resolved :class:`Platform`.
"""
flag: str | None
env: str | None
detected_model: str | None
source: str
platform: Platform
#: Where the Lyra reports itself in the device tree. P0 (2026-08-01) recorded a trailing
#: space before the NUL; re-verified live on-device during P1 (2026-08-01) as exactly
#: ``b"Luckfox Lyra\x00"`` — no trailing space. :func:`_read_device_tree_model` strips
#: whatever surrounds it either way, so this is a documentation correction, not a behaviour
#: change — flagged here in case a different unit/firmware revision does carry one.
_LYRA_MODEL = "Luckfox Lyra"
_DEVICE_TREE_MODEL_PATH = Path("/proc/device-tree/model")
def _read_device_tree_model() -> str | None:
"""Read and normalize ``/proc/device-tree/model``, or ``None`` when it doesn't exist.
Absent on every machine that isn't running a device-tree-based Linux kernel — every
desktop, every CI runner, and (today) every ``ssh`` session onto one of those. This is
deliberately the *only* signal auto-detection consults (no terminal-size guessing), so
a small window on the desktop is never mistaken for the device.
"""
try:
raw = _DEVICE_TREE_MODEL_PATH.read_bytes()
except OSError:
return None
return raw.decode("utf-8", "replace").rstrip("\x00").strip()
def _lookup(name: str, *, source: str) -> Platform:
"""Resolve a platform name to its :class:`Platform`, or raise a clear ``ValueError``."""
try:
return _BY_NAME[name.strip().lower()]
except KeyError:
choices = ", ".join(sorted(_BY_NAME))
# Plain ASCII: this can surface through Typer/Click's own error path (raised
# before make_console() has reconfigured stdout/stderr to UTF-8), which mangles
# non-ASCII on a legacy Windows console the way make_console's docstring warns of.
raise ValueError(
f"unknown platform {name!r} (from {source}) - choose from: {choices}"
) from None
def resolve(flag: str | None = None) -> Resolution:
"""Decide which platform is active, and record what the decision looked at.
Resolution order: the explicit ``--platform`` flag, then the ``MESHTERM_PLATFORM``
environment variable, then device-tree auto-detection, then :data:`REGULAR`. Only the
input that actually decides the outcome is name-validated — an env var typo is
reported when the flag isn't set, but never blocks a session that passed an explicit
(correct) flag.
Args:
flag: The ``--platform`` command-line value, if given.
Returns:
The full :class:`Resolution`, for both immediate use (``.platform``) and the
``meshterm platform`` diagnostic's report.
Raises:
ValueError: The deciding input (flag or env var) named an unknown platform.
"""
found = _resolve(flag)
if _DRAWN_BY_MESHTERM and not found.platform.own_display:
return replace(found, platform=replace(found.platform, own_display=True))
return found
def _resolve(flag: str | None) -> Resolution:
""":func:`resolve`'s decision, before :func:`drawn_by_meshterm` has its say."""
env = os.environ.get("MESHTERM_PLATFORM") or None
model = _read_device_tree_model()
if flag:
return Resolution(flag, env, model, "--platform flag", _lookup(flag, source="--platform"))
if env:
return Resolution(
flag,
env,
model,
"MESHTERM_PLATFORM env var",
_lookup(env, source="MESHTERM_PLATFORM"),
)
if model == _LYRA_MODEL:
return Resolution(flag, env, model, "auto-detect", PICOCALC_LYRA)
return Resolution(flag, env, model, "default", REGULAR)
#: Set while :mod:`meshterm.emulator` runs MeshTerm in a display of its own drawing (see
#: :func:`drawn_by_meshterm`).
_DRAWN_BY_MESHTERM = False
@contextmanager
def drawn_by_meshterm() -> Iterator[None]:
"""Resolve every platform as one MeshTerm draws itself, for as long as this lasts.
The emulator shows a PicoCalc (Lyra) in a window: the platform is that device's in every
respect but one — no console draws it, MeshTerm does — so it resolves with
:attr:`Platform.own_display` set, and nothing about the terminal the emulator was
started from (a classic Windows console to leave, a font to offer) is the emulated
session's business. In-process only: nothing leaks into a child process's environment.
"""
global _DRAWN_BY_MESHTERM
previous = _DRAWN_BY_MESHTERM
_DRAWN_BY_MESHTERM = True
try:
yield
finally:
_DRAWN_BY_MESHTERM = previous
def without_emoji(platform: Platform) -> Platform:
"""The same platform with its icons routed through the compact glyph table.
A terminal that cannot draw emoji is not a different *flavour* — the classic Windows
console has the desktop's width, colour depth and keyboard, and wants every other
thing :data:`REGULAR` says. Only the one flag moves, which is what the seam's flags
being independent is for: ``font`` stays unset, so accents and the rest of the BMP
still come through.
Args:
platform: The resolved platform.
Returns:
``platform`` itself when its icons are already compact, else a copy with
``emoji`` cleared.
"""
return platform if not platform.emoji else replace(platform, emoji=False)
__all__ = [
"Platform",
"REGULAR",
"PICOCALC_LYRA",
"CARDPUTER_ZERO",
"without_emoji",
"PLATFORM",
"get_platform",
"set_platform",
"on_platform",
"Resolution",
"resolve",
]