Claude Skills
The open format is called Agent Skills and works in Claude Code, Codex, Cursor and other agents — most people know it as Claude Skills.
Every Agent Skill we could find on GitHub, deduplicated by content. 79 600 files from 1 763 authors, of which 61 947 are unique — the rest is the same skill repackaged into someone else's repository. For each one: what it weighs in tokens, whether it ships runnable scripts, and which MCP servers it needs.
One StateFlow holds a growing playback queue but has two write paths on purpose — a full setter that resets derived snapshots, and continuation appends that write the backing field directly so those snapshots survive. Use when a feature keyed on "where the queue came from" stops working once the queue auto-extends, or before refactoring two queue write paths into one.
Reading a type marker the remote source declares for itself — normalizing before every comparison because locally stored rows from older app versions hold labels the app invented, treating null as "the source did not say" rather than as a default, exposing an is-known predicate so callers branch on knowledge, and correcting old rows by write-through instead of a migration. Use when a stored type column holds several spellings, when an item is treated as the wrong kind, or before adding a database migration to fix historical values.
Split a span into buckets of exactly equal width and let the remainder fall outside, pick the bucket unit from how many rows a person will read, and never draw a partial newest bucket at full width. Use when a bar chart's oldest or newest bar is inexplicably long or short, when a range produces thirty rows nobody reads, or when one range in a set renders in the opposite direction from the others.
Fire a one-shot celebration effect from the click that caused it, never from the state that click produced — an effect watching a boolean for a false→true edge cannot tell a tap from data arriving a beat later, so moving to an already-marked record fires the same edge. Covers the @Stable holder that owns live effects, judging the meaning at tap time, why the previous-value variable is a second source of truth, and keeping concurrent effects additive. Use when an effect plays by itself while skipping between records, when it celebrates something the user did not do, or when the first genuine tap after a screen returns is silently swallowed.
Clamp long text to a few lines with a more/less affordance driven by measured overflow instead of a character count, and make timestamps or URLs inside the same text tappable. Use when "more" shows on text that already fits, never shows on text that does not, gets truncated along with the text, or when tapping a link expands the block instead of following the link.
Expose a device capability to shared Compose code as a @Composable expect function, with a full implementation on the platform that has it and a stub that returns the neutral value on the platform that does not. Covers the three shapes these take — a measurement, an effect with an undo, and a subscription read as state — and why a stub must still be correct. Use when shared UI needs a window measurement, a keep-awake flag or a windowing-mode state, when one platform stops the app the first time a screen paints, or when a shared screen behaves as if a capability is off on a platform that has it.
Suppress the "ended" playback state at a forwarding-player boundary while the underlying player is being replaced, so the media service is not torn down in the gap between one player finishing and the next starting. Use when background playback stops partway through a queue on some devices but never on your development phone, when the playback notification disappears between tracks, or when the app is frozen by the system mid-queue.
Two independent features want entries in one engine property that holds the WHOLE chain, so writing it replaces everything — keep each feature's entries in its own field, compose them in a single writer, and let "clear" drop only its own tier. Use when a second effect is added beside an existing one, or when one of two effects works and then randomly stops working after a transition.
Counting entities encountered for the first time means taking MIN over the entity's whole history and asking whether that minimum lands inside the window — the natural version, which filters to the window and then groups, calls every entity new. Covers why the wrong query passes its first test, why the window belongs in HAVING rather than WHERE, what an unbounded scan needs from the index, and how a retention prune quietly redefines "ever". Use when a "new this period" figure tracks the distinct count exactly, when discovery rate is implausibly close to 1, or before writing any first-seen query.
Re-subscribe a downstream flow whenever a key flow changes using flatMapLatest, then collapse the resulting high-frequency stream to a composite key with distinctUntilChanged before firing expensive one-shot work. Use when a fetch re-runs on every progress tick, when it fires for the wrong item after a fast switch, or when a side effect never runs because one of its inputs arrives last.
When a user setting picks between two renderings of the same control — an expensive decorative one and a plain twin — every geometry decision has to be mirrored between them (item width, bar height, indicator size, inset, and the rule that computes the width budget) so toggling changes the material and never the layout; the compiler cannot pair two constants declared in two files. Also covers recolouring an icon that arrives as a slot lambda, which only CompositionLocalProvider(LocalContentColor) can reach. Use when switching a visual setting also moves things, when the plain variant's indicator sits off its item, or when a slot-lambda icon ignores every tint you pass.
A control floated over a scrolling column is a sibling that takes part in no measurement, so the column has to reserve the strip it covers explicitly — as a leading spacer, or as a header row whose twin spacers keep a centred title centred over the hole. Covers what the strip constant may and may not count, why every scrolling branch needs its own, and why floating is what keeps the control reachable once the page has scrolled. Use when a floating back button sits on top of the first line of content, when a centred title is off by half a button, or when a control scrolls out of reach on a long page.
Build a follower's playable item from the payload the shared session carries, not by re-resolving it from your own catalogue — a local resolver that infers the rendition from artwork shape lands on the wrong one, and a per-item network round trip inside the apply collector wedges every later command behind it. Use when a follower in a synchronised room gets silent video where the source has audio, or when one slow lookup freezes a client's whole command stream.
A follower in a shared session owns its own stop button — pausing is local and silent, and pressing play asks where the session is now rather than restoring where this device stopped. Use when a follower cannot pause because the next state update immediately resumes it, when a follower's pause stops everyone, or when resuming lands minutes behind the rest of the group.
Keep one part of a Compose app rendered dark — screens drawn over dark artwork — while the rest of the app follows the user's light theme, by providing a whole dark colour scheme plus your own token locals to that subtree; includes why a text-colour flag alone is not enough, and the verified fact that bottom sheets and dialogs inherit these locals across the window boundary while a freshly rooted composition does not. Use when icons or buttons on an image-backed screen turn grey and unreadable in light theme, when a sheet opened from such a screen comes out the wrong colour, or when a forced-dark screen still asks the system whether it is night.
The gesture and chrome layers of a fullscreen video screen — tap anywhere to toggle the controls, double-tap either half to seek, an auto-hide timer that every interaction postpones, and a picture-in-picture (PiP) guard that removes both layers. Use when single taps work on only half the screen, when the controls vanish while the user is dragging the seek bar, when the seek thumb snaps back under the finger, when a double-tap produces no ripple or a ripple that never fades, or when app chrome is still drawn over the video inside a small floating window.
Swap the underlying player beneath a `ForwardingPlayer` at runtime while the media session and the UI keep one stable reference — re-attaching listeners and the video output, and answering the playlist questions a one-item timeline cannot. Use when next/previous buttons vanish from the system notification, when nothing updates after the first swap, when video stops rendering after a track change, or when reporting a playlist index makes the app stop.
Ship one codebase in two forms — a full build carrying a proprietary or credentialed integration and an open build carrying a no-op stub — using twin modules with an identical public API selected by a Gradle property rather than product flavors, which do not exist for non-Android multiplatform targets. Reach for it when a tracking, casting, or paid-service dependency must be absent from an open-source build, when call sites are littered with build-flavor branches, or when the "clean" build still pulls the proprietary artifact through a transitive path.
Put a user's on/off setting for an optional decorative surface treatment inside the one shared primitive that draws it — published from the theme as a CompositionLocal defaulting to on — instead of asking every call site to check the flag. Covers why the off path must keep the shape and the hit target and change only the paint, why the default is true rather than false, and the difference between a call site that picks a material and one that picks a different composable. Use when a settings toggle reaches only some of the surfaces it names, when a gated component renders as a bare box in previews, or when turning an effect off also moves the layout.
One reusable helper that reads an entire table through a (limit, offset) data-access function in a bounded loop, stopping on the first short page — plus when reading everything is legitimate (export, backup, bulk mapping) and the smell that means you needed a real query instead. Use when several repositories each hand-roll the same paging loop, or when a "read all" call gets slower than linearly as the table grows.
Structure a GitHub Actions release pipeline for a multiplatform desktop app so one Linux runner cross-builds every platform's artifacts and a second, tiny macOS job does only the one step that genuinely requires macOS — with artifact handoff between them and no compilation on the costly runner; reach for it when your release workflow runs three OS jobs that each rebuild the world, or when macOS users hit a hard block dialog on an app the pipeline signed correctly.
The composable widget toolkit is not Compose with a different import — it has no aspect ratio, its weight is always 1 so an even split is the entire vocabulary, its corner radius only applies from API 31, and a widget always fills the launcher's cell so the spare height must be spent deliberately. Covers the weighted-spacer trick that keeps square tiles square, and where a fill modifier swallows a whole band. Android only. Use when a square tile renders as a rectangle, when a widget shows a block of dead colour below its content, or when corners are round on one device and square on another.
Build a home-screen widget that renders the app's existing state holder rather than a parallel copy of it, by injecting the same shared state object and the same long-lived scope the app already uses and re-issuing the widget update whenever that state changes. Covers dispatching the app's own UI events from widget buttons, why the injection target must be a singleton rather than a screen-scoped definition, making the whole widget a tap target, turning off hardware bitmaps for artwork the widget must read, and the leak to avoid when starting those collectors from the widget's provide-glance callback. Android only. Use when a widget shows stale playback or session state, when its artwork is blank, when a tap on it opens the launcher's menu or does nothing at all, or when its buttons need their own duplicate logic.
Keep the start conditions of a feature that fires from two entry points — typically a polling loop and an end-of-item callback — identical on both paths, because a condition added to only one of them is dead code that produces no error, no log and no crash. Use when a newly added guard, exclusion or feature flag appears to have no effect at all, or when a feature behaves correctly most of the time and wrongly in one specific timing.
A style or effect option is correctly hidden from a settings picker below some OS version or capability floor, yet the effect it names still shows up broken — flat, unblurred, or simply wrong — on a device that should never be able to select it, because the picker gates what a user can choose next, not what a stored preference already holds. Use when a version-gated visual feature has a capability check in one place but the bug still reproduces, or when adding an expect/actual boolean for a modifier that fails silently instead of throwing.
Move dependency injection from an annotation-processed compile-time framework (Hilt/Dagger) to the multiplatform runtime container (Koin) — the mechanical mapping for providers, view models and qualifiers, what happens to assisted injection, and the two failure modes the migration introduces: a graph that no longer fails at compile time, and a module definition that blocks the thread starting the container. Use when planning the migration, when a binding resolves to nothing at runtime after it, or when app start got slower afterwards.
Bundle a multi-field setting into one immutable value and hand it to a hot consumer as a supplier, so the consumer asks "has this changed?" with a single reference comparison instead of diffing N numbers per buffer — and can never observe the fields half-updated. Use when a per-buffer or per-frame consumer has to react to a user setting, or when a setting made of several fields is read inconsistently.
Retry a record's image at a variant the source guarantees when the high-resolution one is missing, by holding the URL in composition state and swapping it once in onError. Covers making the disk-cache key follow the mutated URL, resetting the state per record, keeping the swap a no-op the second time so it cannot loop, and the invisible cost — everything hanging off onSuccess (a palette, and the page theme derived from it) silently never runs. Use when a page keeps its fallback colour for particular records, when a retried image is re-fetched on every visit, or when an image request appears to retry forever.
Diagnosing Gradle failures of the form "cannot mutate a configuration after its child configuration was resolved" — why the message names the configuration you touched rather than the plugin that resolved it, how to bisect plugins against a minimal working template, and which fixes are documented dead ends. Reach for it when adding a perfectly ordinary dependency line makes the build refuse to configure, and rewriting that line every possible way changes nothing.
Share the boolean that drives a fade, never the tween that runs it — each look derives its own curve, so one can go asymmetric (fast in, slow out) without changing how the other feels; covers why a symmetric linear fade over a bright backdrop makes container-backed controls read as the wrong colour, and why the shared animated value must stay published anyway. Use when buttons look lighter or darker than their neighbours only while something is fading, when one visual style needs a different timing from another, or before pulling an `animateFloatAsState` up into a shared state holder.
Specify a user-facing exchange file — why a version field can be worse than none, rejecting a file whose parse yields nothing, stating the same-length rule that positionally-aligned arrays imply, naming the legacy values a producer must never emit, and, when the producer is someone else's published format, placing values by the key that means something instead of by position. Use when designing an import/export or backup format, when writing a parser for a published one, or when a user reports importing a file and getting nothing with no error.
Pick one boundary convention for a stepping period navigator and hold it everywhere — a closed upper bound at 23:59:59 drops the last second's sub-second remainder, and half-open bounds handed to an inclusive BETWEEN double-count the shared instant — then reset the step offset whenever the granularity changes, because N periods back at one length is not N periods back at another. Covers clamping at the present, deriving the forward affordance from the same value, and why the current period's totals are not comparable to the previous one's. Use when a period navigator lands on the wrong span after switching granularity, when a boundary event is missing or counted twice, or when a first-of-the-month comparison reads catastrophically low.
Hand-writing a JVM binding for a C library with JNA (Java Native Access) — the open-flags option that means something else on Windows, structs read by raw offset, callbacks the binding holds weakly, search paths registered too late, and proving which file was actually opened. Reach for it when a binding works on every developer machine and fails on a clean one, or when the very first symbol lookup fails with "the specified module could not be found" while the library is sitting right there.
A component that is committed to running but not yet running reports "not running", so anything that means intent must read the intent flag, not the observed one — and at a transition the intent flag must be waited for with a timeout rather than sampled inline. Use when one client's buffering hiccup stops a whole synchronised group, when appending to a queue in the background silences the track that was about to start, when a resume command is issued on every tick, or when a state read is wrong on exactly the transitions it exists for.
The state a relay pushes to a new member is the source's last command replayed, so its position is however old that command is — obeying it drops the joiner at the start of something everyone else is halfway through. Ask for the live position the moment you are in, and again whenever this client rejoins the shared timeline. Use when a member who joins mid-session starts from the beginning, or restarts at whatever position they last had locally.
Judge and reduce a desktop JVM application's memory honestly — read the heap-to-footprint ratio rather than the resident figure, run the one experiment that separates a leak from an allocator holding idle pages, and understand why per-thread allocator arenas make the footprint depend on the user's core count. Use when a desktop app settles near a gigabyte or keeps climbing over a long session, when users on big machines report far worse memory than you can reproduce, or before tuning any allocator or garbage-collector flag.
Settings-file patterns for a many-module Kotlin Multiplatform repo — mapping deeply nested in-repo directories onto flat Gradle project paths, turning on typesafe project accessors and knowing how they mangle names, declaring repositories in the two places that need them, and pinning one transitive artifact repo-wide for a conflict that only shows at runtime. Reach for it when Gradle reports a project that "does not exist" from a module you never edited, when a project accessor will not resolve, or when a repository you added is invisible to plugin resolution.
Resolve two extension functions that differ only in their generic receiver's type argument and so compile to a single JVM method, using @JvmName on one of them. Covers what the annotation changes, why it beats renaming the Kotlin function, and what non-Kotlin callers see afterwards. Use when the compiler reports a platform declaration clash between declarations you can plainly see are different, when adding a second converter over the same collection type breaks a file that compiled yesterday, or when a Java caller cannot find a function every Kotlin caller uses.
Consume a git submodule as a set of Gradle modules in a multiplatform repo — mapping its nested directories onto flat project paths, making the recursive clone a hard prerequisite instead of tribal knowledge, and enabling submodules in every continuous-integration job that configures the build. Reach for it when a fresh clone fails with a project that "does not exist", when a build passes locally but fails on a runner, or when shared code changes vanish because the recorded submodule pointer was never moved.
Decode named, hexadecimal and decimal character entities in shared multiplatform code, where the platform's own markup helpers are unavailable. Covers the named table, the two numeric passes, the range check that keeps an out-of-range code point from ending the operation, why running the passes in one order over-decodes, and the rule that decoding happens once and at a boundary. Use when entity text such as `'` or `&` reaches the screen undecoded, when text decoded twice loses characters a user typed, or when a large code point stops the parse.
Put one small logging object in the shared module between every call site and the logging library, so a chatty subsystem can be silenced in one line and the library can be replaced without touching call sites. Covers the muted-tag set, a level-as-a-value enum for callers that pick severity at runtime, and why a single direct import of the library anywhere defeats both. Use when one subsystem drowns the log, when swapping or upgrading a logging library means editing hundreds of files, or when muting a tag has no effect on some of its output.
Split one Kotlin Multiplatform UI module into a shared app LIBRARY plus thin per-platform launcher modules — an Android application module that only packages, and a JVM/desktop module that owns main() and hands off to a public function in the library. Reach for it when the Android Gradle Plugin refuses to let your app module also be a multiplatform target, when packaging config and shared UI are tangled in one build script, or when a resource accessor class stopped generating after a module became a library.
Wrap the multiplatform date-time library's instant-to-local-date-time conversions in a few named helpers — now, epoch converters, comparisons, a shifted-window helper and a relative \"time ago\" formatter — so call sites read as intent instead of ceremony. Covers what each wrapper must pin explicitly, and the trap family behind it: a helper reading one time zone while persistence reads another, arithmetic done on wall-clock types, a formatter that can only run during composition, and a parse failure that returns a legal value. Use when stored timestamps come back shifted by the device's offset, when a duration is wrong only around a clock change or only for some users, or when a relative label stays stale on screen.
A multiplatform HTTP stack where one expect/actual hands back the engine and each integration builds its own client from it — an instrumented client for API calls next to a deliberately bare one for bulk downloads, content negotiation registered per format, and a settings change that rebuilds the client rather than mutating it. Use when standing up networking in a Kotlin Multiplatform module, when a proxy setting appears to be ignored by some requests but not others, or when downloading a large file crawls and floods the log.
A lazy list's `spacedBy` arrangement applies between every pair of items and compounds with each item's own edge padding, so blocks that must read as one unit belong in ONE item carrying its own tighter spacing rather than in three items relying on the list's gap. Covers why the visible gap appears in no single constant, why an item boundary is a spacing boundary, and what to do when the group is conditional. Use when a band of dead space opens above one block, when tightening the gap for one pair moves every other pair, or before splitting a header into separate lazy items.
Building a swipeable now-playing page whose layers — a colour backdrop, a full-bleed looping video or image, and a centred square cover — all belong to one pager, with per-page colours taken from the bitmap that page actually painted and a scrim spanning the whole page. Use when a swipe makes the background and the cover slide out of step, when video from one track bleeds into the neighbouring page mid-swipe, when the backdrop colour belongs to the wrong track or flashes black between pages, when the bottom of the video shows through the controls, or when a tap overlay stops the pager from being dragged at all.
A complete drag-to-reorder state holder for a lazily composed Compose list — pointer offset accumulation, target-index math over the visible window, how the lift animation and the built-in item placement animation must not overlap, edge auto-scroll as a delta the caller drives, and the commit-on-drop contract with the data layer. Use when building reorder, or when a dragged row snaps back to its old slot, jitters as the list re-lays-out under it, commits a move that the user cancelled, or scrolls the list instead of moving the row.
Wiring view models through a runtime dependency-injection container without losing track of their lifetime — the service-locator base class and what it costs, annotation-based definitions that compile but register nothing, which store owner each accessor addresses and why that (not the accessor's spelling) decides whether two screens share an instance, and what registering a view model as a process-wide singleton makes you responsible for. Use when a view model resolves to a fresh instance that should have been shared, when a lookup fails at runtime for a class that is clearly annotated, or when state vanishes between screens.
Four small lazy-list utilities worth carrying between apps — scroll-direction as derived state, centre-an-item scrolling that waits a frame before measuring, an item's visible percentage, and a lookup into the visible window — with the trap each one hides. Use when a hide-on-scroll bar flickers or sticks, when scrolling to an item lands it at the edge or does nothing, or when viewport arithmetic returns values for the wrong item.
Match a string against a candidate list with a two-row edit-distance loop and no dependency, so the matcher lives in shared multiplatform code. Covers the two-row memory shape, normalizing before comparing, a similarity threshold that refuses rather than returning the least-bad candidate, picking a top-N without corrupting the indices, and the cases where fuzzy matching is the wrong tool. Use when a title-to-title lookup picks a confidently wrong candidate, when a "top 3" helper returns indices that point at the wrong rows or at -1, or when a matcher cannot move into shared code because the library it uses is platform-only.
Matching a machine-generated id inside a text or JSON column with LIKE — why `_` and `%` in the id silently widen the match, how to escape them with nested replace() plus an explicit ESCAPE character, and why the id must be matched as a quoted token rather than as a bare substring. Reach for it when a cleanup spares rows it should have deleted, when a lookup returns a row belonging to a different id, or before putting any id into a LIKE pattern.
Build refracting "liquid glass" surfaces in Compose with a backdrop library, and avoid the three failures that waste the most time — a rim highlight that is directional by default and so goes nearly invisible on small round buttons, a backdrop source nested inside the glass it feeds, which is a render-feedback loop that stops the shader, and a source with nothing in it, which renders the control as a grey coin over a flat page. Covers the source/surface split, giving a flat page a ground worth refracting rather than dropping the effect, the white default tint that only suits forced-dark screens, the effect stack, keeping the press gesture observe-only, and the swap experiment that tells a geometry problem from a placement problem. Use when a glass surface renders as a flat rounded box or a grey coin, when the rim shows on a wide pill but not on a circular button, when its glyph disappears at light theme, or when the draw pass crashes inside the shader.
Build per-user listening or usage analytics entirely on-device — an append-only event table plus a denormalized per-contributor table that carries a copy of the timestamp, two completion thresholds instead of one, bare ids in events enriched to titles and artwork only at read time, and every window query parameterised as (start, end) so "last N days" stays an argument. Use when adding a "your year in review" or top-items screen without a backend, when a time-window chart is slow, when a chart is mysteriously shorter than the row count says it should be, or when a per-contributor total refuses to add up to the period's own figure.
Logging out must reset every setting that depended on being logged in, at the logout choke point itself — otherwise a gated switch stays on for a service you are no longer authenticated to and silently no-ops forever, or errors on every tick. Use when a feature toggle is stuck on, cannot be switched off, or keeps running against a credential that is gone.
Strip the `._*` companion files that macOS archiving writes beside files carrying extended attributes, after unpacking anything into a macOS app bundle and before the bundle is signed, because the signer seals those companions as ordinary bundle members and the OS deletes them the first time the file manager touches the app. Use when a signed macOS app launches fine on the build machine but users are told it is damaged and can't be opened, or when signature verification reports a sealed resource missing.
Render one heterogeneous list with one composable by tagging unrelated classes with an empty interface, plus a nested enum each implementor answers where the renderer has to branch. Covers when a tag beats a sealed hierarchy, the exhaustiveness you give up in exchange, and the ways an item silently stops rendering. Use when the items come from modules that cannot be sealed into one file, when a newly added item type appears as a blank row nobody noticed, or when two tags want the same accessor name and one class needs both.
Ship every icon as a generated ImageVector extension property on one receiver object, fetched from the icon font's own Compose generator, so the bytecode shrinker can drop the ones you never reference. Covers the generator request and its axis parameters, the edits that turn a generated file into an extension property, the filled/unfilled pairing for state icons, and which icons must stay as drawable resources. Use when adding or replacing an icon, when a set has drifted into mismatched weights and corner styles, or when a type error reports an ImageVector where a Painter was expected.
Write a custom audio processor for a Media3/ExoPlayer audio pipeline — a filter, a fade, a gain stage — that is toggled at runtime and shared across several concurrent players. Use when a processor you added does nothing until the next track, when playback wedges with no error, when `put(ByteBuffer)` throws on your own output buffer, or when two simultaneous players need one parameter to reach both.
Playing a separate audio-only stream and video-only stream as ONE source on JVM desktop through the media engine's edit-list URL form — the desktop counterpart of a merging media source — including length-prefixed quoting of stream URLs and why a merged two-URL item must not be prepared in the middle of a crossfade. Reach for it when desktop video plays back completely silent with nothing in the log, when a stream URL is truncated at the first semicolon, or when fading into a video track cuts the outgoing song short.
An opt-in switch that mirrors a local flag onto a signed-in remote account — turning it on back-fills everything already flagged, turning it off stops mirroring and deliberately does not undo, and the per-item call is three-valued so "not attempted" is distinguishable from "failed". Covers writing locally first and unconditionally, which of the two paths is allowed to speak to the user, and why the back-fill is sequential. Use when a mirrored flag silently disagrees with the account, when the user cannot tell a failure from a no-op, or before wiring a settings switch to a remote write.
Claude Skills — questions
Answers built from the skills we actually parsed.