A Portuguese user reported "Skip Intro" rendering in English on Android TV.
The locale files were not the problem - all 22 were structurally complete.
skip_marker_button.dart simply never imported strings.g.dart and assigned
'Skip Intro' / 'Skip Credits' / 'Next Episode' as plain literals. An audit of
lib/ found ~120 more sites in the same state, in four shapes that need
different fixes:
A literal in a file that never imported the i18n layer is the easy one -
skip_marker_button, performance_stats, track_label_builder and codec_utils all
render text with no `t` in the file at all. TrackLabelBuilder._compose now takes
a fallbackLabel builder instead of an English fallbackPrefix, so the caller
supplies t.audioTracks.track / t.videoControls.subtitleTrack and every unnamed
audio and subtitle row in the track menus is localized.
English reaching the user through an exception message is the widest one, and
it needs care: MediaServerException.message feeds both toString() - logs and
Sentry grouping - and verbatim UI display. Localizing it in place would make
bug-report logs follow the user's locale and split one Sentry issue into 22.
The MediaServer and Seerr families instead gain a nullable `display` alongside
the English `message`, and the six screens that print these errors read
`display ?? message`. PlaybackException keeps the opposite rule, because it
already carries a PlaybackFailureReason for logic and classifyPlaybackFailure
already builds it from t.messages: its stragglers are localized at the throw
site. That also removes the literal "Exception: " prefix Live TV users saw on
a tune failure, since PlaybackException.toString() returns the bare message.
Localized parts hand-concatenated with bare English are the shape no search for
Text('...') can find: '${t.common.pause} auto-scroll' on the home carousel,
'${day} at ${time}' on the Live TV schedule row, and an actor-screen count that
hand-rolled its plural as `n == 1 ? 'title' : 'titles'` - wrong for ru and pl
regardless of translation, now a real Slang plural.
Finally a literal assigned to provider state that a widget renders later:
DownloadProgress.errorMessage, and the four background_downloader notification
bodies, which sit inside a plugin config call where no widget-shaped search
reaches them.
Two things surfaced while converting. track_chapter_controls compared a track
label against 'Audio Track N' to swap in a localized version; once the builder
localized its own fallback that branch became unreachable, so it and the
orphaned _joinTrackLabel are gone. And discovery_view's PeerError fallback arm
looks like a leak but is not - its producers already localize, and a test says
so - so it stays as it is.
All 21 non-base locales are translated, including the 21 keys left empty by
earlier commits that were falling back to English. No locale has an empty value.
scripts/check_hardcoded_strings.py guards the three shapes a structural check
can see, and runs in ci_checks.sh after translation hygiene. Its first draft
passed its own tests while missing this very bug, because 'Skip Intro' is bound
to a local rather than handed to Text(); the name-bound rule that closes that
gap is restricted to phrase-shaped literals, or it cannot tell copy from the
identifiers this codebase binds constantly ('cast_row', 'auto', 'liveTv'). It
cannot see English inside a throw or assigned to a provider field - neither is
distinguishable from a log message without dataflow analysis - and the docstring
says so. label: and actionLabel: are deliberately unscanned: here they name a
diagnostic operation, and a check that is chronically red is a check that gets
switched off.
One commit rather than one per area: the keys, the 22 locale files and the
generated output are a single unit, and any partial split fails the repo's own
unused-key scan on the way through.
close#1856
Watchlist membership was only reachable from Explore cards and the
detail screen's action row, which drops the bookmark first on narrow
screens with no fallback in the overflow menu. Add an entry to
MediaContextMenu for movies and shows whenever a connected catalog
source can hold the item, covering card long-press everywhere and the
detail screen's overflow.
External-id resolution is session-cached per item on
CatalogSourcesProvider and shared with the detail screen. A cold cache
labels the entry "Add to Watchlist" and always adds (idempotent), so a
press can never turn into a surprise removal; "Remove" is offered once
cached membership proves it. Several capable sources open the same
per-source chooser the detail screen uses.
close#1822
The Top Shelf extension now fetches Continue Watching directly from
Plex/Jellyfin/Emby instead of replaying a cache the app wrote on its
last foreground Discover pass. The app publishes per-profile server
descriptors on every shelf sync (`updateSources`): token-free metadata
in the app group, tokens in an app-group-shared keychain item, both
wiped by `clear`. On success the extension rewrites the cached payload
as the offline fallback; any fetch failure falls back to the previous
cache-replay behavior. Poster images are passed as remote URLs, so the
extension no longer depends on app-side artwork downloads.
Episodes now render season/series poster art (2:3, `.poster` shape)
instead of 16:9 episode stills, and labels lead with the S/E marker so
long titles no longer hide it behind the focused-item marquee. Shelf
schema v3 (Dart, Android, tvOS envelopes bumped together) discards
stale wide-art caches instead of letterboxing them into poster slots.
close#1474close#1835
Pausing an episode on one device, finishing it on another and pressing
Refresh left the first device showing the old "minutes left". Restarting the
app showed the right value. Two independent defects produce that, and either
alone reproduces the report.
The first is the watch-state overlay. Every local watch event lands in
WatchStateStore as a patch, and WatchStateSnapshot.apply overwrites
viewOffsetMs unconditionally; isNewerThan only ever orders one patch against
another, never against the server row underneath. Nothing expires a patch and
nothing clears the map except a profile switch, so the Mac's own paused
position kept winning over every subsequent fetch until the process died.
A patch exists to bridge the gap between a local action and the next server
read of that item, so it should stop applying once that read happens. The
store now records the watermark at which a successful authoritative response
returned each key, and suppresses an acknowledged session patch at or below
it. Only a watermark is stored, never the observed state: WatchStateSnapshot
cannot hold a container's leaf counts, and keeping max() per key makes the
order two concurrent responses complete irrelevant. Suppression is a
read-time predicate, so nothing mutates during build.
The barrier covers the parentChain too. patchForItem picks the newest of the
item's own entry and its ancestors', so retiring only the item's entry would
let an older season mark win and render watched/0 -- worse than either the
stale value or the fresh one. An authoritative read of a child already
reflects any container mark that preceded it, so the child's observation
judges its ancestors as well; a newer container action still wins.
Provenance decides what may be suppressed at all. WatchStateEvent now carries
serverAcknowledged, defaulting to false so an unclassified emit site degrades
to today's behaviour rather than silently becoming retireable. An offline
write is owed to the server and a read must never retire it, so it stays
until a WatchPatchPromotionNotifier promotion says the queue replayed it. That
channel is deliberately not a WatchStateEvent: OfflineWatchSyncService reacts
to watched/unwatched by purging queued progress, so replaying one there would
delete a newer rewatch. Promotion matches an exact WatchPatchId -- session
minted for live crossings, derived from the persisted (profile, row, revision)
for queued ones so it still joins after a restart.
Report acceptance is not delivery: PlaybackReportSession resolves true for a
same-state startup heartbeat it drops, so acknowledgement now keys on
onDelivered. A MediaBrowser Started saves play count and last-played date but
not the position, so it cannot acknowledge an offset. No report-derived
watched crossing is acknowledged on any backend -- Jellyfin hard-codes its
threshold and Plex never loads the server pref that would tell it the real
one -- so only an awaited explicit markWatched settles one.
The second defect is that a failed Refresh reported success. Plex _fetchHubs
and the Jellyfin hub legs both degrade a failure to an empty list, and the
library prefetch discarded its failures, so a server whose every hub request
failed was recorded as succeeded; DiscoverProvider then kept the previous rows,
set loaded and surfaced nothing. Worse, the background Continue Watching
refresh wiped the row outright on zero success.
Hub legs now report what they degraded through a HubFetchDiagnostics sink,
which keeps partial rows alongside the failure and leaves every existing
caller untouched. Failures ride through the aggregation results, a leg that
could not run because discovery failed contributes that failure rather than a
successful no-op, and loaded-server ids became succeeded - failed - cancelled
so one bad leg no longer caches a server as covered and blocks its retry. The
toolbar awaits a DiscoverRefreshOutcome and shows the existing unableToLoad
snackbar on failure while the retained rows stay on screen. Rollback after a
mid-pass exception is version-guarded, refilters against the current hidden
libraries and no longer publishes a system shelf the pass never committed.
Observations are staged with the pass and flushed only once the same disposal,
generation and exception checks that authorise committing those rows have
passed, so a discarded or rolled-back response can never suppress a patch.
Also fixes a live data-loss race the promotion work would have built on:
upsertProgressAction stamped a millisecond timestamp and updated the row in
place, so a rewatch queued during an in-flight replay was deleted by id.
Revisions are now strictly monotonic per row, replay deletes and retry updates
compare against them, and the upsert resets the retry fields because a new
revision is a new logical action.
close#1829
Since 2.10.0 the app opens on a Flutter-owned startup frame, and that frame
paints an opaque themed Scaffold before any preference is readable. Its
themeMode defaults to system, so the theme comes from platform brightness --
and a TV has no system dark-mode toggle, so Fire TV and Shield report light.
The result was a near-white #F7F7F8 sheet held for the whole gate, from
prefs through Sentry to the database open, over an Android window the
television resource qualifier had already painted black. Before 2.10.0 the
gate ran ahead of runApp and no Flutter frame existed to cover it.
Nothing in the loading frame is worth covering the launch screen for. Android
composites Flutter in TransparencyMode.transparent over a window whose colour
MainActivity already restored from plezy_prefs, so the loading Scaffold is
transparent there and the launch screen carries the launch. Every other
platform composites opaquely with nothing behind Flutter, so they keep
painting their own background.
The spinner and the failure screen still need a colour, and platform
brightness is the wrong one for exactly the devices this bug is about, so the
startup frames now adopt the persisted theme once it can be read. TV
detection has to run before that read: the theme_mode default is TV-aware and
isTVSync answers false until its singleton exists, which would resolve a
fresh Android TV install to the light theme. Both singletons are memoised and
awaited again by the gate. The read is best-effort -- an unreadable store is
the gate's failure to report, not this path's -- and it also stops a startup
failure from rendering as a full-screen white error page on a TV.
darkThemeFor and materialThemeModeFor move onto ThemeProvider so the startup
frames and the provider resolve OLED from one mapping rather than two.
Verified on an Android TV emulator in television/notnight mode, clean install,
cold start: peak frame luma 228 for 78 frames before, 0 frames above 120
after, and the same on a returning launch.
close#1833
Marking a movie or episode watched left it sitting in Continue Watching with a
checkmark, and the only way to shift it was to play it and skip to the end.
Continue Watching membership on a MediaBrowser server is derived from
UserData.PlaybackPositionTicks alone; Played is never consulted. Marking played
normally zeroes that position as a side effect, so the row usually disappears
and nothing ever checked that it had. When something writes a position back
afterwards the item is left played *and* resumable, which the resume route
happily keeps returning forever. markWatched now reads the UserItemDataDto the
mark already returns and clears the bookmark itself when the server left one
behind, so the postcondition holds however the item got into that state. The
follow-up write costs a request only when the invariant is actually broken.
The writer putting items there is our own offline queue. insertWatchAction
already drops queued progress for an item when the mark is itself queued, but
the online mark writes straight to the server and queues nothing, so a progress
row recorded earlier survived and replayed afterwards — pending actions go out
oldest first — restoring the very position the mark had cleared. The sync
service now listens for watch-state events and discards queued progress for
that item as the mark lands. Progress recorded after a mark is a rewatch and is
queued later, so it is untouched. Plex never showed this because it forwards the
recorded-at timestamp and lets the server discard a stale replay; the
MediaBrowser stop report has nowhere to put one.
Continue Watching also drops the row locally now instead of waiting a round trip
for the refetch to confirm it, matching what removal events already did, and
marking a season or show takes its on-deck episode with it.
Watched items are deliberately still not filtered out of the shelf: Jellyfin
keeps Played set when new progress arrives, so a rewatch in progress is
indistinguishable from a stuck row, and filtering would hide it.
close#1812
Connects MDBList through its OAuth device-code grant, registered as a
Device Code app so no client secret or redirect URI ships in the binary
and TV, mobile and desktop all use the same flow.
MDBList omits `verification_uri_complete`, but its device page seeds the
code field from a `user_code` query parameter and the sign-in redirect
preserves the query string, so the activation link is built locally and
the dialog's open button lands on a filled-in form instead of an empty
one. A server-supplied complete URL still wins if one ever appears.
Poll state is read from the response body rather than the status code:
`authorization_pending` and `slow_down` both arrive as HTTP 400, and a
missing grant answers 404 `device_not_found`.
Writes go out as real-time `/scrobble/*` reports plus `/sync/watched`
for the marks that never pass through the player, with ratings on
`/sync/ratings`. Matching uses IMDb and TMDb only — MDBList's id block
has no `tvdb` field, so a TVDB-only item is skipped rather than written
under an empty id block.
Emby is Jellyfin's upstream ancestor and speaks a near-identical MediaBrowser
API, so the existing Jellyfin stack is parameterised by a `MediaBrowserDialect`
rather than forked. `JellyfinClient`, its auth service, endpoint discovery, LAN
discovery, and the add/edit connection screens all take the dialect and keep one
implementation; `MediaBackend.emby` and `ConnectionKind.emby` carry it through
the neutral models, the Drift `kind` discriminator, downloads, and caches.
Every divergence below was measured against a live Emby 4.9.5 server, not
inferred from documentation, and each is documented at its capability getter.
Jellyfin's request strings stay byte-identical so nothing about its behaviour
changes.
Routes and auth
- Emby only accepts the pre-10.9 user-scoped item routes (`/Users/{id}/Items/…`,
`/Users/{id}/PlayedItems/…`, `/Users/{id}/FavoriteItems/…`); the unprefixed
forms Jellyfin 10.11 added return 404.
- The API is also served under a legacy `/emby` prefix, and both dialects accept
the token as `X-Emby-Token` or `api_key=`.
- Emby answers only its own LAN discovery datagram ("who is EmbyServer?") and
ignores Jellyfin's; its default HTTPS port is 8920.
- No `/QuickConnect` route exists, so Quick Connect stays Jellyfin-only.
Row fields Emby withholds
- `ProductionYear`, `OfficialRating`, `PremiereDate` and `DateCreated` are absent
from list rows unless named in `Fields`, which would otherwise strip the year
and age-rating badge from every card in the app.
- `UserData.LastPlayedDate` never appears on a list row under `Fields=UserData`,
`EnableUserData=true` or the user-scoped `Ids=` form — only on the single-item
detail route, or when the Emby-specific `UserDataLastPlayedDate` token is
requested. Without it every recency-ordered surface silently degrades to
library-add time, and `JellyfinApiCache.applyWatchState` stamps
`DateTime.now()` on watched rows, so an offline watch-state pull would rewrite
the cached play time of everything it walked.
Continue Watching and Next Up
- Emby computes Next Up per series only: the library-wide `/Shows/NextUp` query
returns nothing under every parameter combination tried. The shelf is
therefore reconstructed from a played-episode recency scan plus one
`/Shows/NextUp?SeriesId=` per distinct series, bounded by a shared wall clock
that covers the scan as well — per-request timeouts cannot bound the pass
because `MediaServerHttpClient` times the connect and receive phases
independently. Rows are stamped with their series' newest play from the same
response that ordered them, so no per-series enrichment request is needed.
- `/Shows/NextUp` ignores `NextUpDateCutoff`, and no server-side played-date
filter exists to delegate to (`MinDatePlayed` and `MinDateLastPlayed` are
ignored; `MinDateLastSaved`, `MinDateCreated` and `MinPremiereDate` filter
unrelated dates), so the 365-day window is applied to the scanned dates.
- The resume route returns items with no saved position, including plain next
episodes, so the Emby resume leg reads from `/Items?Filters=IsResumable`.
- Emby is ahead of Jellyfin in one place: `/Users/{id}/Items/{id}/HideFromResume`
makes Continue Watching removal a real capability.
Everything else
- `/Sessions/Playing` and `/Sessions/Playing/Progress` reject a body with no
`PlaySessionId` (HTTP 400), so playback reporting always sends one.
- Passing any `MediaTypes` value to the playlist query returns an empty list.
- There is no aggregate `/Items/Filters` route; the four filter facets are
reassembled from `/Genres`, `/OfficialRatings`, `/Studios` and `/Tags`.
- Metadata writes take name-pair lists (`Genres: [{'Name': 'Action'}]`); the
plain string array is accepted and then silently discarded.
- Custom artwork uploads must be base64 text, not raw bytes — which was broken
for Jellyfin too and is fixed for both.
- Trickplay, media segments and lyrics 404 on Emby, so scrub previews are absent
and intro/credit markers fall back to chapter names.
Verified against a local Emby 4.9.5 and a Jellyfin 10.11.11 control server:
onboarding, browse, detail, playable stream URLs serving real bytes, subtitle
sidecars, watch-state write and restore, hubs, cross-server aggregation and
search across both backends simultaneously.
The Discover tab fanned out its whole request set twice on every cold
start and replayed slow rows on a shrinking timeout ladder, so a healthy
remote server produced anywhere from 4s to 15s of loading.
Measured against a remote Jellyfin server with four libraries, 24
interleaved cold-start samples per side:
requests 19 -> 9 payload 219 KB -> 94 KB
settled 5231ms -> 2502ms median, 13222ms -> 5927ms p95
Four independent causes:
- Retry policy. `Client.send` resolves on response headers, so the
connect budget covers the server's think time and a slow-but-alive
query raises `connectionTimeout`. Replaying it made the server re-run
the query with a shorter budget than the one it just missed; the
`[10s, 8s, 5s]` ladder turned an 11s answer into an empty row after
23s. Hub surfaces now get one whole-request deadline, retry only
immediate connection errors, and the deadline bounds the whole call
including the request still in flight.
- Request shape. `/Items/Latest` groups a TV library by series, so its
rows are Series folder dtos and `RecursiveItemCount`/`ChildCount` cost
a DB count each, per row. Hub rows now ask for `Overview` only; watch
state survives because Jellyfin derives `UserData.Played` from
`UnplayedItemCount` when the count fields are absent. `/Shows/NextUp`
sends `NextUpDateCutoff` to bound the server's series-key scan, and
`Thumb` leaves `EnableImageTypes` since nothing reads it. `UserData`
and `PremiereDate` leave the browse set: neither is an `ItemFields`
member, so the server dropped them anyway.
- Fan-out. Per-library hubs ran in batches of three separated by a
barrier, so one slow library stalled every library behind it. A
sliding window keeps the same peak concurrency without head-of-line
blocking. Concurrent `fetchLibraries` calls now share one `/Views`
instead of racing two identical round trips, Plex's global and music
hub legs start together, and Jellyfin gets Plex's pool tuning.
- Duplicate pass. `DiscoverScreen.initState` starts a load and the
online-entry hook asked for a full refresh on top of it, which
`CoalescedLoadCoordinator` correctly queued as a trailing pass. The
hook now calls `primeRefresh`, which rides along with a load already
in flight; profile switches still go through `fullRefresh`.
Refs #1784
Trakt was the one service outside the tracker abstraction. TraktScrobbleService
re-implemented the whole playback lifecycle beside TrackerCoordinator, and
TraktSyncService pushed watched state from its own WatchStateNotifier
subscription, so the player called two objects at every lifecycle point and one
watch could be written twice. TraktTracker now implements RealtimeScrobbleTracker
like Simkl; the duplicated player call sites collapse to one each, and Trakt
shares the coordinator's ID resolver instead of re-fetching show ids every
episode.
Capabilities are split so a tracker declares what it is rather than being
special-cased: ScrobblePolicy carries each service's own resend/seek rules,
EpisodeHistoryTracker names the remote row a per-item history write targets, and
SeriesProgressTracker covers one-counter-per-series services. Writes from all
four trackers go through a shared TrackerWriteQueue, generalised from the
Trakt-only queue, with the legacy Trakt payload migrated on load. Trakt becomes
the fourth TrackersProvider slot and TraktAccountProvider is deleted, so one
object owns the active session per profile.
Two failure paths found while consolidating are fixed here too.
The queue's retries only ran on profile bind, connect and app foreground, so a
network blip mid-session left queued watches waiting for the next foreground.
OfflineModeProvider now notifies on connectivity changes, not just offline-state
or WiFi-flag changes, and main.dart flushes the queue when the network returns.
The queue also counted every failure toward the five attempts that permanently
drop an item, so a rate limit or a service having a bad hour could discard a
pending watch - the loss the queue exists to prevent. Only an answer about the
write itself now spends an attempt: 4xx counts, while rate limits, 5xx,
recoverable token-refresh failures and requests that never arrived do not. A
back-off answer also defers that service for the rest of the flush, so a queue
holding many rows does not fire all of them at a service that just asked for
quiet.
Explore shelf cards drew a poster, a title and a year. An audit of all six
catalog sources found the rest was lost at two boundaries — the wire-to-DTO
mapping and the DTO-to-CatalogItem mapping — and then simply not drawn: the
grid card fell through every branch of buildMetadataSubtitle to the year-only
case, while the list card used by search already composed certification,
runtime and rating from fields the synthesized MediaItem already held.
Extend CatalogItem with the neutral facts every provider had been dropping:
attributed rating sources, leaderboard ranks that keep their season window,
audience counters that keep their timeframe, broadcast slots, next-episode air
times, server availability and request state, exact release dates, alternate
titles, format, source material, studios, countries, languages, credits, tags,
links, artwork variants, play state, gallery art and background prose. Replace
fetchCast and fetchRelated with one fetchDetail returning the enriched item,
its cast, its recommendations and labelled franchise relations without adding
a request: sources needing two calls keep two and run them concurrently with
isolated failures.
Map those fields in all six sources, widening only field selections that cost
no extra round trip — MAL's fields list, AniList's selection set and a bounded
row cast that lets detail skip its character call, Trakt's guest stars, Seerr's
language parameter and TMDB size ladder, and Plex's includeUserState. Plex hub
artwork widens only on TV, where the spotlight is its only consumer, because it
doubles the payload.
Render them: a rating-first caption and bounded badges on the shelf card,
labelled sections on the detail screen, provider hub styles and result counts
on shelves, and logo, banner and accent art in the TV spotlight.
Verified against live Plex, AniList, Simkl and MAL responses, and on a Pixel 7.
Plex Explore showed only the Watchlist row. `/hubs/sections/watchlist`
answers with placeholder hubs — every entry carries `placeholder: true`,
`size: 0` and no `Metadata` — so `fetchHubs` mapped each one to an empty
page and dropped all of them. That is true no matter what the profile has
watchlisted; the shelves never rendered.
Read `/hubs/sections/home` instead, the section Plex's own web client
renders on its Home > Trending tab, and hydrate each placeholder from its
own key (six at a time). `directory` shelves list browse categories and
`clip` shelves list trailers, neither of which becomes a catalog item, so
they are skipped before spending a request. A shelf that fails degrades to
the ones that succeeded; a pass where every shelf failed still throws.
Discover ignores container offsets on hub keys and truncates with `limit`
instead, so a hub is one page: View All takes the whole shelf in a single
request rather than replaying page one, and hub requests drop `Media` and
`Image` elements the catalog layer never reads.
`dart format --set-exit-if-changed` over lib and test rewrites these.
The analysis job never reached its formatting step, so the drift went
unnoticed. No behaviour changes.
Consolidates duplicated logic behind shared implementations — paginated
grid tabs, focus chrome, cached remote stores, sheet selection columns,
the server artifact store and a test fixture layer — and removes code
that had become unreachable. Net reduction of about 5,500 lines with no
behaviour change.
Where a fix had landed separately in code that moved into a shared
helper, the fix was re-applied inside the helper rather than left behind
in the copy that went away.
The search screens, the out-of-band auth dialogs, the live TV guide and the
list-download paths each carried their own copy of the same shell. Extracts
SearchInputField and PendingAuthDialog and routes the duplicated download
and guide helpers through one implementation.
Focus chrome was implemented twice, once in the focusable wrapper and once
in the focus builders; both now go through FocusChrome. TvColorPicker's
channel row was a copy of TvNumberSpinner and is now that widget in compact
density.
Also trims unused helpers and fields and simplifies the Jellyfin browse
paths.
Extracts the repeated toolbar fade into a single ToolbarScrim widget, folds
duplicated request/retry handling in the media server HTTP client, and
collapses the parallel playback-source, download-manager and live TV helper
paths into shared implementations.
- Merge SeerrMovieDetails/SeerrTvDetails into one SeerrDetails model and
route both detail endpoints through a single request helper.
- Replace the three parallel tracker session/store/rebind-generation
triples in TrackersProvider with a _TrackerSlot record plus one _rebind
path.
- Fold the three JellyfinSequentialLauncher entry points onto a shared
_launchLocalQueue helper that owns loading, abort, shuffle and publish;
each caller now supplies only its fetch.
Introduces shared seams for paginated views, D-pad reorder, media control
routing, async singletons and the device method channel, then points the
open-coded copies at them.
Also removes unused models and duplicated provider/server plumbing, folds
the twice-implemented artifact store in the server, and factors the
repeated Flutter toolchain prologue in CI into a composite action.
edde746