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Vance IngallsandClaude Opus 5
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* feat(core): audio FX registry One declarative description of every effect that can be applied to an audio track: fourteen across filters, dynamics, non-linear and time, each exposing its full parameter surface rather than a curated subset. Parameters carry the range, step, unit and scale a control needs, so a panel can generate its UI from this rather than hard-coding a form per effect, and a value that survives `normalizeAudioFxParams` is always safe to realise. Everything is declared in the units a person thinks in — dB, ms, Hz. Parsing rejects an unknown effect id rather than skipping the node. A chain that quietly loses an effect renders something other than what was authored, which is worse than refusing to load it. Data only: no audio is produced here. The graph that realises each effect is referenced by the `web` id and lands in the next change, which keeps this module free of browser globals so the engine and the linter can import it. * fix(core): stop declaring knobs that move nothing Three parameters were declared with ranges, defaults and hints, and read by no builder — dials an author could turn with no audible result. - `chorus.decay` and `bitcrush.aa`: removed. FFmpeg's chorus feeds a decay back into its delay line and a bitcrusher's anti-alias needs a real filter; adding either is new DSP, not a fix, so the honest move is to stop advertising them. - `lowshelf.q` / `highshelf.q`: removed. The Web Audio spec leaves Q unused for shelving filters, so the control moved nothing — and because the shared Q helper marks it automatable, an author could draw an envelope on it and hear nothing at all. `phaser.decay` and `gate.knee` stay: the first drives the sweep depth, and the second is now read by the gate's processor. A test asserts each of these directly, since the existing exposure invariant only checks that a flagged parameter reaches an AudioParam — a parameter the node then ignores passes it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(core): Web Audio graphs for the FX registry One graph builder per `web` id, turning the registry's declarations into running audio. Every node exposes `update`, so turning a dial re-parameterises the live graph rather than rebuilding it: an AudioParam change lands on the next 128-sample quantum, about 2.7 ms at 48 kHz. `buildFxChain` reports whether an update could be applied in place — adding or bypassing an effect, or switching a filter between one and two poles (which changes the node type from BiquadFilterNode to IIRFilterNode), changes the graph's shape and returns false so the caller rebuilds. Four effects have no native node and run as AudioWorklet processors: compressor, limiter, gate and bitcrush. The module is registered from a data: URL rather than a blob:, because a blob inherits the page origin and is opaque on a file:// page, where it fails with an unhelpful AbortError. Reverb has no single node either. `synthesizeReverbImpulse` generates a tail from the room parameters, seeded so the same room sounds the same on every machine, and the ConvolverNode uses it. Tests cover the wiring — which nodes get built, how they connect, parameter application and clamping, in-place update versus rebuild, disposal — against a fake AudioContext, since happy-dom has no Web Audio. * fix(core): reverb level, phaser wiring, per-channel dynamics, one-pole rebuild Four defects in the graph builders, all found by review rather than by ear. **Reverb was unusable at its own defaults.** A ConvolverNode applies the impulse's gain whole — the graph sets `normalize = false` so a room is deterministic rather than browser-defined — but the impulse was raw decaying noise. Measured L2 at the registry default (size 0.7 / damping 0.5): 46.4, or +33.3 dB, putting the wet path ~24 dB over dry at the default `wet: 0.35`. It is now normalised to unit energy, so the wet knob means what it says. Preview and render both convolve this buffer, so they stayed identical throughout — equally deafening before, equally correct now. **Phaser in_gain/out_gain trim the signal entering and leaving the effect**, not a wet/dry pair. Wired to the wet and dry legs, "Input" muted the dry path and the two defaults summed to 1.14, so inserting a phaser raised the track level. They are now input and output trims with the legs summed at unity. Its declared waveform is also honoured: `lfo.type` was never assigned, so the default "Triangular" was silently a sine. **The dynamics worklets held one envelope across a channel-major loop.** The followers advance per sample, so on stereo a 20 ms attack behaved as 10 ms, and the right channel's gain came from an envelope that had already traversed the left — the two ducked differently from the same input and the image pumped. State is now per channel, as is the gate's smoothed gain and bitcrush's sample-hold counter, which previously advanced only on the last channel and left every earlier one frozen for a whole quantum. The gate also honours the knee it declares instead of chattering on material sitting at the threshold. **A one-pole filter's cutoff was swallowed in preview.** Its coefficients are fixed at construction, so `update` cannot push a new frequency — but the shape signature carried only type and pole count, so a cutoff change looked like a values-only edit and went into a no-op updater. Preview kept filtering at the old frequency while the render used the new one: a preview/render divergence in exactly the two effects that do not use a BiquadFilterNode. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(engine): render audio FX in an OfflineAudioContext Reads `data-fx-chain` off an audio element and runs the chain over the trimmed WAV before volume automation is baked in — effects should see the raw signal, and the envelope belongs on their output. The processing happens in an OfflineAudioContext inside the headless browser the engine already drives, running the same graph builders the studio previews with. That is the point of the approach: one implementation per effect, so the render agreeing with the preview is a property of the architecture rather than a tolerance to police. Reimplementing each effect as an FFmpeg filter would mean two implementations to keep in step, and for the dynamics processors and modulated delays there is no filter that behaves the same way. `build:audio-fx-runtime` bundles the graph builders into an injectable IIFE, following the same pattern as the existing runtime artifacts, so the browser runs exactly the code the studio does. The page loads from a file:// URL rather than about:blank because AudioWorklet is only exposed in a secure context — the compressor, limiter, gate and bitcrush processors would otherwise fail to register with an opaque error. file:// qualifies and needs no listening socket. The chain is serialised into the attribute the way colour grading carries its config, so there is no side-car file to resolve or lose. An FX failure is fatal for the whole mix rather than a per-track soft failure. Every other audio failure mode degrades gracefully — the track drops, siblings continue — but substituting the dry signal for a processed one ships a render that sounds plausible and is not what the author set up. Since the per-element work races under Promise.all, an internal AbortController chained off the caller's signal aborts in-flight siblings before workDir is removed. * feat(core): voiceover carve analysis Finds the bands a voice occupies so a music bed can be dipped there, letting the voice sit in front without ducking the whole track. Carve is a relationship between two tracks rather than an effect on one, so it stays out of the FX chain. What it emits is an ordinary chain of peaking filters, so a carve composes with whatever else is on the track and needs no separate rendering path. Selection is weighted toward intelligibility rather than raw voice energy. Ranking purely by power lands on the fundamental almost every time, because that is where a voice is loudest — but the masking that actually hurts a voiceover happens higher up, and dipping 160 Hz mostly just thins the bed. The bias is a control, not a constant: at 0 it follows raw energy, at 1 it weights toward 1-3 kHz. Ranking happens in dB, which matters more than it looks. Speech spreads 20-30 dB across these bands — it falls off roughly 6 dB per octave above the fundamental — so a weighting has to be on that scale to move anything at all. A multiplicative weight of `1 - bias + bias * shaped` is bounded below by `1 - bias`, capping its influence at 10*log10(1/(1 - bias)): 5.2 dB at the 0.7 default, 3 dB at 0.5. That is no influence against a real voice — every bias short of ~0.95 would rank exactly like bias 0 and carve the fundamental, the outcome the bias exists to prevent, while looking decisive against a fixture whose bands sit 2 dB apart. So the bias is a dB penalty, zero at 2 kHz and worth up to 30 dB at full strength, and relative cut depths come from a dB difference rather than a ratio of weighted linear powers. The bias reweights ranking without overriding the spectrum — a band the voice has no energy in is not worth carving, and scores -Infinity rather than competing — so a strongly low-pitched voice can still select low at full bias. What the tests hold is that biasing never selects lower than the unbiased ranking, that the DEFAULT bias reaches the presence region on a voice with a realistic tilt, and that bias 0 still follows raw power exactly. Includes a radix-2 FFT rather than a dependency; one Welch-style averaged spectrum over third-octave bands does not justify pulling in a DSP library. * fix(engine): keep the FX render 16-bit, stereo, and correctly sized Three defects in the offline FX path, none of which any test could see. **Float output silently disabled sample-accurate volume automation.** The writer emitted 32-bit IEEE float; the very next mixer step bakes the volume envelope into the samples and accepts only 16-bit PCM, returning null otherwise. So enabling any effect downgraded that track to the ffmpeg expression path — capped at 32 straight segments, quantising a curved envelope, and on a dense one falling back to base volume. It now writes 16-bit PCM, clamped rather than wrapped so a limiter at 0 dB or a resonant filter cannot turn overshoot into a click. A test asserts the baker accepts the writer's own output and actually fades it. **Everything was folded to mono.** `prepareAudioTrack` goes out of its way to emit stereo — its pan filter exists to dodge ffmpeg's 3 dB mono-to-stereo rematrix — and this folded it, then wrote one channel. So adding a single peaking EQ collapsed a bed's width and cost ~3 dB in the render, while preview stayed stereo. Channels now travel as one plane each, through an OfflineAudioContext of the same width, and come back interleaved. **Small results decoded the wrong length.** `new Float32Array(buf.buffer)` discards byteOffset and byteLength, and Node pools small allocations: a 400-byte payload sits at offset 8 inside an 8 KiB pool, so a clip under ~1024 samples decoded as 2048 samples of unrelated memory — and the empty-result guard could not see it. The reader has the mirror-image fix: a float data chunk on an odd boundary (ffmpeg's pcm_f32le writes fmt(18) + fact, landing `data` at 58) now copies instead of throwing RangeError on an unaligned view. The tail limitation is now stated rather than mis-stated: the context is exactly as long as the input, so a reverb or delay still ringing is cut there. The old comment claimed the opposite. How far a tail may run past a clip's end changes the clip's length in the mix, so it is a product decision, not one to make here. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix(producer): report an FX render failure as an audio error `processCompositionAudio` reports per-track failures in its result, but an FX failure it cannot degrade past — a browser that will not launch, a chain that will not build — rejects instead. `runAudioStage` had no try, so that rejection escaped to the orchestrator as an unclassified pipeline exception, losing the stage/owner/retryable classification this stage exists to attach, and skipping its abort check on the way out. It now lands in `audioError` alongside every other cause, while an abort still keeps its own shape rather than being reported as an audio problem. Not done here: committing the generated `audio-fx-runtime-inline.ts` so a fresh clone typechecks packages/engine without building first. The bundle is built from the stub, and the stub changes three times across this stack — so the artifact differs per branch and would conflict on every restack. Its model, position-edits-render-inline.ts, is committed only because it is stable. Building before testing is this monorepo's existing contract (studio's tests need core's dist too), so the gap is not specific to audio FX and is better closed by a build ordering gate than by committing a per-branch artifact. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * test(engine): skip the browser FX render cases when there is no browser CI's `Test` job was red on this PR with four failures, all the same cause: Failed to launch the browser process: spawn /home/runner/.cache/hyperframes/chrome/chrome-headless-shell The job installs ffmpeg and no browser, deliberately — every other suite that needs an external binary already guards on it (`describe.skipIf(!HAS_FFMPEG)`). These cases were the only ones assuming a Chrome, so they failed on an absent dependency rather than on anything about the code. Guards on `resolveHeadlessShellPath()` — the same resolver `acquireBrowser` launches through, so the check cannot drift from the thing it guards the way a hard-coded cache path would. A configured path that does not exist throws; that is caught and read as "cannot run here". Checked both directions rather than just the green one: with a browser all 11 cases run and pass, and with `HYPERFRAMES_BROWSER_PATH` pointed at a missing binary exactly 3 skip and the other 8 still run. A guard that silently skipped everything would have looked identical in CI. They keep their value where it exists — every developer machine, and any job that has run `hyperframes browser ensure`. Not touched: the CodeQL failure on this PR is a run from 2026-08-07, five days and several force-pushes stale. None of the 17 open repo alerts are in files this PR changes; it re-runs on this push. * chore(engine): suppress the temp-file alert with the reason it is safe CodeQL flags `writeWav`'s `writeFileSync` as js/insecure-temporary-file (high) — the one new alert on #3021, and the reason its CodeQL check is red. It is a false positive, and the comment says why rather than just silencing it: `path` is always inside a directory made by `mkdtempSync`, never a name assembled directly under `tmpdir()`. Both callers are covered — the browser host page writes into `mkdtempSync(join(tmpdir(), "hf-fx-host-"))`, and the render output goes to the producer work dir, itself `mkdtempSync(join(tempRoot, "producer-project-"))`. mkdtemp picks the random suffix and creates the directory 0700 in one syscall, so the predictable filename inside it cannot be pre-created or symlinked by another user, which is the attack the rule is about. The analyzer sees the dataflow reach `tmpdir()` and not the mkdtemp in between. Suppressed inline rather than dismissed in the UI, so the justification lives next to the code and the rule stays live for anything added later in this file. Matches the repo's existing convention — `planV2.ts:222` carries an `lgtm[js/insecure-temporary-file]` for a different reason on the same rule. Correcting myself: I first reported this alert as not real, having intersected the PR's files against the default-branch alert list, which does not contain PR-ref alerts. Querying ?ref=refs/pull/3021/merge returns it straight away. * feat(core): register the audio-fx-rack canary at 0% Lands the rollout switch dark, per the registry's own procedure: "Start at percentage: 0 and merge that — a canary at 0 is dead code you can land safely and ramp without a code review." Declared at the bottom of the stack so every branch above can read it. The gate itself goes in at wa-4-fx-panel, where the rack first appears. Scope is deliberate and stated in the description: it gates the AUTHORING surface only. A composition that already carries `data-fx-chain` still plays and renders it. A canary should stage who can REACH a feature, not make an attribute somebody already wrote silently inert — an agent that writes a chain through the skill would otherwise produce a file whose audio processing vanishes with no error. * feat(studio): audio FX panel generated from the registry Controls for the whole chain: add, remove, reorder, bypass, and every knob each effect declares. Nothing in the panel knows what a compressor is. The registry supplies each parameter's range, step, unit and scale and the panel renders what it finds, so adding an effect or a knob upstream needs no change here, and the panel cannot offer a value the renderer would reject — a typed-in figure is clamped into the declared range on the way through. Frequency and time controls span three or four decades, so those declare a log scale and the slider maps exponentially; a linear slider would spend most of its travel somewhere useless. Reorder is a first-class control because chain order changes the sound: a reverb before a compressor is not the same as after. Carve gets its own block rather than an entry in the add menu, with a picker for the voice track to listen to. It processes this track based on another one, which is how a sidechain control works — it lives on the track that changes, and names the source. * feat(studio): show the Audio FX section on audio tracks Adds `audioFx` to the editing-affordances contract and renders the FX panel in the inspector when an `<audio>` element is selected. The section is audio-only. A `<video>` carries its sound on a separate `<audio>` element, so an FX chain on the video would have nothing to process. Chain and carve settings are written straight back onto the element as serialised attributes, the way colour grading carries its config, so persistence is an ordinary attribute write and needs no new server route. A chain that cannot be parsed renders as empty rather than breaking the panel, and the attribute is left untouched until the user changes something. The collapsed group summarises what is on the track ("2 effects + carve") so the state is visible without expanding it. Wired into PropertyPanelFlat rather than PropertyPanel: STUDIO_FLAT_INSPECTOR_ENABLED defaults to true, so the flat inspector is what actually renders. * refactor(studio): lift audioFxSummary out of PropertyPanelFlat `PropertyPanelFlat.tsx` is 612 lines here against the repo's 600-line cap, so the required File size check is red — the sole reason this PR is blocked. The review says as much: "mechanical fix (~5 min), not a design problem. Code itself is LGTM." Moves `audioFxSummary` to `audioFxSummary.ts`, the same file a later branch creates for it. Deliberately the smallest cut that clears the cap rather than the whole `AudioFxGroup` extraction: every later commit in the stack edits AudioFxGroup, so moving it here would collide with each of them, while almost nothing touches this function. 595 lines. * feat(studio): put the audio FX rack behind its canary Gates the rack on `isCanaryEnabled("audio-fx-rack")`, which is registered at 0% — so the whole 47-PR stack can land without showing anyone a feature that has not been measured yet. The gate sits on the AUTHORING surface and nowhere else. The runtime and the render still honour a `data-fx-chain` already on an element, so a composition written through the skill or by `carve.mjs` keeps its processing rather than going silently dry for anyone outside the cohort. A canary should stage who can REACH a feature, not make an attribute somebody already wrote stop working with no error. Gated at the panel rather than in `resolveEditingSections`: the affordance resolver is a pure function in core describing what an element CAN support, and rollout state is not a property of an `<audio>` tag. Pinned the 0% with a test, and checked it fails at 25 — a ramp should have to break something that says "this ships dark" out loud. One gap, stated rather than papered over: the gate itself has no unit test. I wrote one and deleted it, because `PropertyPanel.test.tsx`'s harness never renders the Audio FX group for its audio fixture even with the gate removed — so the test passed for the wrong reason in the off case and could not pass at all in the on case. A test that cannot fail for the right reason is worse than none. Verifying the gate needs the panel harness to mount that section first, which is its own change. * feat(core,studio): hear the FX chain in preview, and run the carve analysis Splices an element's FX chain into the playback graph so preview stops being silent about effects, and wires the carve button that was previously inert. The chain goes between the decoded source and its gain stage: effects see the raw signal and volume automation rides on their output, matching the order the offline render uses. Since preview and render call the same graph builders, what is heard while scrubbing is what gets written. The splice lives in the transport rather than on the `<audio>` element. The transport plays each track from a decoded AudioBuffer and mutes the element to avoid doubling, so capturing the element with createMediaElementSource would have processed a stream nothing is listening to — it looked like it worked because the call succeeded, and the audio was unchanged. A chain that cannot be built plays dry rather than silencing the track, which is the right failure in preview: the author keeps working and hears the source. The render still refuses, because shipping the dry signal there would be wrong. Carve now analyses for real: it decodes the chosen voice track, ranks its bands and writes the resulting peaking filters onto this track. Generated nodes are tagged `fromCarve`, so re-running replaces the previous carve instead of stacking another set on top of hand-added effects. Known limitation: the graph is built when a source is scheduled, so a knob turned mid-playback takes effect on the next play or seek rather than immediately. Live re-parameterisation needs the transport to hold the handle and forward updates. * fix(studio,core): stop parameter drags from restarting playback Dragging a knob wrote the chain through the persisting attribute path on every input event. That path refreshes the preview, which reloads the composition and reschedules audio — so a single drag reloaded dozens of times and playback stuttered the whole way. Drags now go through `onSetAttributeLive`, the same path colour grading uses for scrubs: it coalesces undo entries and sets `skipRefresh`, so no reload happens. The persisting write fires once, when the gesture ends — pointer-up or blur for a slider, Enter or blur for a typed value. A select commits immediately since there is no drag to wait for. While dragging, the control is driven from local state. Waiting for the value to round-trip through the element attribute made the knob lag behind the pointer. For the change to be audible without a reload, the graph now follows the attribute: the chain installed by the transport observes the element and re-parameterises itself in place, so a value change lands on the next 128-sample quantum. A shape change (effect added, bypassed, pole count) cannot be patched into a running graph, so it still waits for the next schedule rather than cutting the audio mid-play. The regression test drags a slider through several values and asserts the persisting handler is untouched until release. * fix(core): register FX worklets before building nodes that need them An AudioWorkletNode cannot be constructed before its processor is registered — it throws, and the surrounding chain is lost with it. `attachElementFxChain` built the chain first and only then called `ensureAudioFxWorklets`, so every worklet-backed effect (compressor, limiter, gate, bitcrush) threw on construction and the track fell back to dry. Instrumenting the preview showed `hf-compressor: InvalidStateError` with addModule never called at all. When the module has not landed yet the track now plays dry and the graph is swapped in once registration resolves, so the effect arrives a moment late instead of never. Registration is also tracked per context rather than in one module-level promise. A processor registered on one AudioContext does not exist on another, so the shared promise made every context after the first believe it was ready when it was not — the studio's transport owns its own context, which is exactly that case. With the worklets actually running, the compressor's per-sample log10 and pow became real audio-thread work. Samples below the knee have a gain of exactly unity and need neither, so the envelope is now compared in the linear domain and the transcendentals only run for samples that are actually being compressed. * refactor(studio): split the FX node row out of FxSection Clears the health findings the FX stack left behind: the chain-node render callback was a 70-line closure over half of FxSection's state, and the two reorder arrows were the same button written twice. Also drops two exports with no consumers, and registers the audio FX runtime stub as an entry point — it is bundled by file path, so nothing imports it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * refactor(studio): lift the audio FX group out of PropertyPanelFlat `PropertyPanelFlat.tsx` was 672 lines against the repo's 600-line cap, so the required File size check was red — the sole reason #3014 and #3022 are blocked. Both reviews say the same thing: "mechanical fix, not a design problem. Code itself is LGTM." Moves `AudioFxGroup` and `audioFxSummary` into `propertyPanelAudioFxGroup.tsx`, which is where a later branch puts them anyway — done here so the file is under the cap from the point it first crosses it, rather than ten branches later. 533 lines now. The four audio imports it no longer needs go with it. Not fixed here: three `FxSection carve` tests fail on this branch with "Cannot read properties of undefined (reading 'toFixed')". Confirmed pre-existing by stashing this change and re-running — that is the separate `Test` failure the review also flags. * feat(core): automation envelope model for audio tracks Adds the data model behind Ableton-style automation lanes: breakpoint envelopes over track volume or one knob of one effect in the track's FX chain, stored on the element as `data-automation`. Times are clip-local, so an envelope travels with the clip when it moves — the clip-envelope model rather than arrangement automation. `sampleAutomationLane` is the single interpolator. The lane drawing, the preview scheduler and the render bake all call it, so the picture and the sound cannot disagree about the curve. Log-scaled parameters interpolate in log space, matching what their own knob already promises. FX nodes gain a stable `id`, minted by count rather than randomly so the document is the same on every machine. Lanes address nodes by id, so reordering a chain never re-points a lane at a different effect, and a lane whose effect was deleted is dropped rather than left to reattach. Also warns when a track carries both a volume lane and a GSAP volume tween, since only the lane is heard and the tween silently does nothing. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(core): expose the AudioParams behind automatable FX knobs Marks the knobs an automation lane can drive and has each graph builder hand back the AudioParam behind them, so a scheduler can write to a running effect without knowing what the effect is. A knob is not always one AudioParam. A wet/dry mix is two gains moving in opposition, and a knob in milliseconds drives a delay time in seconds, so each target carries the mapping out of the knob's own declared unit. What stays unautomatable is stated where it is decided: a WaveShaper curve, a convolution impulse and a one-pole filter's coefficients are all rebuilt wholesale rather than scheduled, and the four worklet effects take values by postMessage rather than through AudioParams. The registry flag is written by hand, so a test builds every effect and checks the exposure both ways — nothing flagged is missing, nothing exposed is unflagged. A flag that lied would offer a lane that silently did nothing. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(core): play automation envelopes in preview Schedules each lane onto the AudioParams behind its knob using native ramps and value curves. Nothing evaluates the envelope per frame: it is handed to the audio thread once, so it stays sample-accurate however busy the main thread is, and the offline render will schedule it the same way. Timing comes from the transport, so an envelope survives seeking into the middle of a clip, a clip that has not started yet, and a playback rate that compresses clip seconds into context seconds. A straight line is only scheduled as a ramp when nothing bends it — no curvature, a linear parameter scale, and no unit mapping. Log-scaled parameters and mapped ones are sampled instead, since a delay knob in milliseconds and a wet/dry pair moving in opposition are not linear in the parameter they drive. Lanes with nowhere to write are skipped rather than reported: a one-pole filter exposes no frequency param, and the worklet effects expose none at all. Editing an envelope mid-playback re-aims it at the live playhead rather than restarting the track. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(engine): bake automation envelopes into the render The offline render schedules FX lanes with the same scheduler preview uses, inside the OfflineAudioContext that already runs the same graph builders. The input WAV is the clip's own audio from its first sample, so clip-local time is offline time and the envelope needs no offset. Volume lanes take the existing PCM bake rather than a second mechanism: the lane is converted to keyframes, so a straight fade stays two of them and only a bent segment is sampled — the baker interpolates linearly and would otherwise quietly straighten the curve. A volume lane supersedes keyframes probed from the timeline, which `lint` already warns about. A browser test sweeps a lowpass from below a 2 kHz tone to well above it and measures both ends. Parsing the envelope is not the same as scheduling it, and only running the real thing tells the two apart. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix(core): make the volume lane audible in preview The envelope was scheduled onto the transport's gain AudioParam, but the runtime rewrites that gain every tick from `data-volume` and the GSAP-seeked value — so it was erased within a frame. Volume automation was correct in the render and inaudible while previewing. The lane now feeds the per-tick path where the probed volume keyframes already sit, checked ahead of them so the two cannot fight, and the transport no longer schedules volume at all: one mechanism instead of two racing. The cost is honest — in preview the level steps per tick rather than per sample, exactly as the existing keyframe path does. The render still bakes it into the PCM sample-accurately, and FX parameters are still scheduled on their own AudioParams, since nothing rewrites those. Parsed lanes are cached by attribute text: the runtime asks once per tick per track, and parsing there would run the JSON parser 60 times a second for a value that only changes on an edit. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix(core): apply chain edits to the running graph A structural edit — an effect added, removed, bypassed, or a filter's pole count switched — was dropped. `buildFxChain`'s update reports false when the change is not merely new values, and the attribute observer ignored that, so the edit only took hold when the persisting write reloaded the composition. That reload restarted every playing track, which is what was heard as the audio chopping. The graph is now swapped in place: the old effects are detached, the new ones built and connected between the same source and gain, and any lanes re-scheduled onto the new nodes. The source node is never touched, so playback does not restart. A track with no chain is watched too, rather than wired through and forgotten, so adding its first effect is heard the same way. That means the function always returns a disposer instead of null for the empty case. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(studio): the geometry and plumbing behind automation lanes Everything an automation lane needs before there is a lane to look at, kept apart from the component so the maths can be read and tested without a pointer. `automationLaneGeometry` is pure: which parameters a clip can automate (its fader, then each automatable knob of each effect that carries a node id), how a value maps to a position in the lane, and how a lane is edited. Two decisions live here and are worth review: - A log-read knob maps on its own log scale, so the middle of a 100 Hz–20 kHz lane is the geometric mean. Dragging and drawing then agree with what the knob's own scale already promises. - `withLane` replaces a lane in place rather than appending. A lane with no explicitly chosen parameter shows whichever comes first, so moving the edited one to the end would switch the lane out from under the pointer on the first edit. `automationLaneData` parses the two attributes, cached by their text so the identity only changes when the text does — the lane holds an optimistic draft while a point is dragged and compares against that identity, and a fresh object on every playhead tick would throw the drag away. It binds automation to the chain the way preview and the render bind it, so a lane whose effect was deleted is dropped rather than drawn against the wrong axis. `useAutomationLanes` routes edits through the DOM edit session, targeting the selected element because that is what the attribute commit path writes to. Row height reserves each lane at its own height rather than counting it as another keyframe lane, and `TimelinePropertyLanes` gains a footer slot so the lanes share the keyframe disclosure — and its `aria-controls`. `TimelineElement` moves to its own module: playerStore had reached the 600-line studio ceiling exactly and could not carry another field. It is re-exported from there, so no importer changes. 🤖 Generated with [Claude Code](https://claude.com/claude-code) * fix(studio): make automationLaneData reviewable, and evict one entry not all The cache key held a literal NUL byte instead of its escape, so git classified the whole module as binary: it landed as `Bin 0 -> 2677 bytes` with zero diffable lines, invisible to review, to grep, and to any textual merge. The escape is behaviour-identical. With the file readable, two things in it needed fixing. Eviction cleared the entire map. Clearing changes the identity of every lane's automation at once, and a lane compares its drag draft against that identity — so one unrelated element arriving at the limit would release an in-progress drag and snap the point back. It now drops the oldest entry, and a hit is re-inserted so it counts as recently used. Nothing tested this module, which is what let the binary blob through. Now covered: identity stability, re-parsing when the chain changes but the automation text does not, a hot entry surviving 40 evictions, and an unreadable attribute reading as nothing. The geometry module's exports are ignored for dead-code while its consumer sits one PR upstack, following the convention already used for the fast-capture stack. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix(studio): carry the audio FX attributes onto every timeline row Both element builders read `data-fx-chain` and `data-automation` off the host element, and an expanded sub-composition child is built without one — so an audio track inside a sub-composition reserved no automation height and drew no lanes, while the property panel, which reads the live DOM selection rather than the row, still showed its chain and its toggles. `hostElementState` exists to re-inherit exactly this class of host-only field; it now covers these two alongside `hidden`, `timelineLocked` and `timelineRole`. `parseTimelineFromDOM` had the same gap and now reads both directly. Also exempts the offline FX render's browser entry from the health gate: it runs only inside the headless page the engine drives, so its CRAP score is coverage-driven rather than complexity-driven, and its behaviour is covered by the engine's real-browser render tests. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(engine): render audio FX in an OfflineAudioContext Reads `data-fx-chain` off an audio element and runs the chain over the trimmed WAV before volume automation is baked in — effects should see the raw signal, and the envelope belongs on their output. The processing happens in an OfflineAudioContext inside the headless browser the engine already drives, running the same graph builders the studio previews with. That is the point of the approach: one implementation per effect, so the render agreeing with the preview is a property of the architecture rather than a tolerance to police. Reimplementing each effect as an FFmpeg filter would mean two implementations to keep in step, and for the dynamics processors and modulated delays there is no filter that behaves the same way. `build:audio-fx-runtime` bundles the graph builders into an injectable IIFE, following the same pattern as the existing runtime artifacts, so the browser runs exactly the code the studio does. The page loads from a file:// URL rather than about:blank because AudioWorklet is only exposed in a secure context — the compressor, limiter, gate and bitcrush processors would otherwise fail to register with an opaque error. file:// qualifies and needs no listening socket. The chain is serialised into the attribute the way colour grading carries its config, so there is no side-car file to resolve or lose. An FX failure is fatal for the whole mix rather than a per-track soft failure. Every other audio failure mode degrades gracefully — the track drops, siblings continue — but substituting the dry signal for a processed one ships a render that sounds plausible and is not what the author set up. Since the per-element work races under Promise.all, an internal AbortController chained off the caller's signal aborts in-flight siblings before workDir is removed. * feat(core): voiceover carve analysis Finds the bands a voice occupies so a music bed can be dipped there, letting the voice sit in front without ducking the whole track. Carve is a relationship between two tracks rather than an effect on one, so it stays out of the FX chain. What it emits is an ordinary chain of peaking filters, so a carve composes with whatever else is on the track and needs no separate rendering path. Selection is weighted toward intelligibility rather than raw voice energy. Ranking purely by power lands on the fundamental almost every time, because that is where a voice is loudest — but the masking that actually hurts a voiceover happens higher up, and dipping 160 Hz mostly just thins the bed. The bias is a control, not a constant: at 0 it follows raw energy, at 1 it weights toward 1-3 kHz. Ranking happens in dB, which matters more than it looks. Speech spreads 20-30 dB across these bands — it falls off roughly 6 dB per octave above the fundamental — so a weighting has to be on that scale to move anything at all. A multiplicative weight of `1 - bias + bias * shaped` is bounded below by `1 - bias`, capping its influence at 10*log10(1/(1 - bias)): 5.2 dB at the 0.7 default, 3 dB at 0.5. That is no influence against a real voice — every bias short of ~0.95 would rank exactly like bias 0 and carve the fundamental, the outcome the bias exists to prevent, while looking decisive against a fixture whose bands sit 2 dB apart. So the bias is a dB penalty, zero at 2 kHz and worth up to 30 dB at full strength, and relative cut depths come from a dB difference rather than a ratio of weighted linear powers. The bias reweights ranking without overriding the spectrum — a band the voice has no energy in is not worth carving, and scores -Infinity rather than competing — so a strongly low-pitched voice can still select low at full bias. What the tests hold is that biasing never selects lower than the unbiased ranking, that the DEFAULT bias reaches the presence region on a voice with a realistic tilt, and that bias 0 still follows raw power exactly. Includes a radix-2 FFT rather than a dependency; one Welch-style averaged spectrum over third-octave bands does not justify pulling in a DSP library. * fix(engine): keep the FX render 16-bit, stereo, and correctly sized Three defects in the offline FX path, none of which any test could see. **Float output silently disabled sample-accurate volume automation.** The writer emitted 32-bit IEEE float; the very next mixer step bakes the volume envelope into the samples and accepts only 16-bit PCM, returning null otherwise. So enabling any effect downgraded that track to the ffmpeg expression path — capped at 32 straight segments, quantising a curved envelope, and on a dense one falling back to base volume. It now writes 16-bit PCM, clamped rather than wrapped so a limiter at 0 dB or a resonant filter cannot turn overshoot into a click. A test asserts the baker accepts the writer's own output and actually fades it. **Everything was folded to mono.** `prepareAudioTrack` goes out of its way to emit stereo — its pan filter exists to dodge ffmpeg's 3 dB mono-to-stereo rematrix — and this folded it, then wrote one channel. So adding a single peaking EQ collapsed a bed's width and cost ~3 dB in the render, while preview stayed stereo. Channels now travel as one plane each, through an OfflineAudioContext of the same width, and come back interleaved. **Small results decoded the wrong length.** `new Float32Array(buf.buffer)` discards byteOffset and byteLength, and Node pools small allocations: a 400-byte payload sits at offset 8 inside an 8 KiB pool, so a clip under ~1024 samples decoded as 2048 samples of unrelated memory — and the empty-result guard could not see it. The reader has the mirror-image fix: a float data chunk on an odd boundary (ffmpeg's pcm_f32le writes fmt(18) + fact, landing `data` at 58) now copies instead of throwing RangeError on an unaligned view. The tail limitation is now stated rather than mis-stated: the context is exactly as long as the input, so a reverb or delay still ringing is cut there. The old comment claimed the opposite. How far a tail may run past a clip's end changes the clip's length in the mix, so it is a product decision, not one to make here. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix(producer): report an FX render failure as an audio error `processCompositionAudio` reports per-track failures in its result, but an FX failure it cannot degrade past — a browser that will not launch, a chain that will not build — rejects instead. `runAudioStage` had no try, so that rejection escaped to the orchestrator as an unclassified pipeline exception, losing the stage/owner/retryable classification this stage exists to attach, and skipping its abort check on the way out. It now lands in `audioError` alongside every other cause, while an abort still keeps its own shape rather than being reported as an audio problem. Not done here: committing the generated `audio-fx-runtime-inline.ts` so a fresh clone typechecks packages/engine without building first. The bundle is built from the stub, and the stub changes three times across this stack — so the artifact differs per branch and would conflict on every restack. Its model, position-edits-render-inline.ts, is committed only because it is stable. Building before testing is this monorepo's existing contract (studio's tests need core's dist too), so the gap is not specific to audio FX and is better closed by a build ordering gate than by committing a per-branch artifact. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * test(engine): skip the browser FX render cases when there is no browser CI's `Test` job was red on this PR with four failures, all the same cause: Failed to launch the browser process: spawn /home/runner/.cache/hyperframes/chrome/chrome-headless-shell The job installs ffmpeg and no browser, deliberately — every other suite that needs an external binary already guards on it (`describe.skipIf(!HAS_FFMPEG)`). These cases were the only ones assuming a Chrome, so they failed on an absent dependency rather than on anything about the code. Guards on `resolveHeadlessShellPath()` — the same resolver `acquireBrowser` launches through, so the check cannot drift from the thing it guards the way a hard-coded cache path would. A configured path that does not exist throws; that is caught and read as "cannot run here". Checked both directions rather than just the green one: with a browser all 11 cases run and pass, and with `HYPERFRAMES_BROWSER_PATH` pointed at a missing binary exactly 3 skip and the other 8 still run. A guard that silently skipped everything would have looked identical in CI. They keep their value where it exists — every developer machine, and any job that has run `hyperframes browser ensure`. Not touched: the CodeQL failure on this PR is a run from 2026-08-07, five days and several force-pushes stale. None of the 17 open repo alerts are in files this PR changes; it re-runs on this push. * chore(engine): suppress the temp-file alert with the reason it is safe CodeQL flags `writeWav`'s `writeFileSync` as js/insecure-temporary-file (high) — the one new alert on #3021, and the reason its CodeQL check is red. It is a false positive, and the comment says why rather than just silencing it: `path` is always inside a directory made by `mkdtempSync`, never a name assembled directly under `tmpdir()`. Both callers are covered — the browser host page writes into `mkdtempSync(join(tmpdir(), "hf-fx-host-"))`, and the render output goes to the producer work dir, itself `mkdtempSync(join(tempRoot, "producer-project-"))`. mkdtemp picks the random suffix and creates the directory 0700 in one syscall, so the predictable filename inside it cannot be pre-created or symlinked by another user, which is the attack the rule is about. The analyzer sees the dataflow reach `tmpdir()` and not the mkdtemp in between. Suppressed inline rather than dismissed in the UI, so the justification lives next to the code and the rule stays live for anything added later in this file. Matches the repo's existing convention — `planV2.ts:222` carries an `lgtm[js/insecure-temporary-file]` for a different reason on the same rule. Correcting myself: I first reported this alert as not real, having intersected the PR's files against the default-branch alert list, which does not contain PR-ref alerts. Querying ?ref=refs/pull/3021/merge returns it straight away. * test(engine): probe ffmpeg and Chrome instead of assuming them Two failures on #3021's Test job, both about the environment rather than the code under test. **Bare `ffmpeg` is not on PATH in CI.** The 16-bit fixture shelled out to `execFileSync("ffmpeg", ...)` and died with ENOENT. The job does provide ffmpeg, through `prepare-ffmpeg-bin`, which is what `getFfmpegBinary()` resolves — every other ffmpeg-dependent suite in this package already goes through it. Now this one does too, and the case is `skipIf(!HAS_FFMPEG)` so a contributor without ffmpeg skips rather than fails. **The browser guard trusted the wrong thing.** It asked `resolveHeadlessShellPath()` and treated a returned path as "a browser is here". CI's cache holds a chrome-headless-shell that resolves and then fails to spawn — a partial download is indistinguishable from a working one by `existsSync`, which is all that resolver checks. So the three browser cases ran anyway and failed on the launch. It now runs `--version` and requires exit 0, which is the same probe the ffmpeg suites use: ask the binary, do not infer from the filesystem. Checked both directions rather than just the green one. With a working browser all 11 cases run and pass; with `HYPERFRAMES_BROWSER_PATH` pointed at a binary that exits non-zero — CI's exact situation — exactly 3 skip and the other 8 still run. A guard that quietly skipped everything would have looked identical on the CI summary. * feat(core): register the audio-fx-rack canary at 0% Lands the rollout switch dark, per the registry's own procedure: "Start at percentage: 0 and merge that — a canary at 0 is dead code you can land safely and ramp without a code review." Declared at the bottom of the stack so every branch above can read it. The gate itself goes in at wa-4-fx-panel, where the rack first appears. Scope is deliberate and stated in the description: it gates the AUTHORING surface only. A composition that already carries `data-fx-chain` still plays and renders it. A canary should stage who can REACH a feature, not make an attribute somebody already wrote silently inert — an agent that writes a chain through the skill would otherwise produce a file whose audio processing vanishes with no error. * feat(studio): audio FX panel generated from the registry Controls for the whole chain: add, remove, reorder, bypass, and every knob each effect declares. Nothing in the panel knows what a compressor is. The registry supplies each parameter's range, step, unit and scale and the panel renders what it finds, so adding an effect or a knob upstream needs no change here, and the panel cannot offer a value the renderer would reject — a typed-in figure is clamped into the declared range on the way through. Frequency and time controls span three or four decades, so those declare a log scale and the slider maps exponentially; a linear slider would spend most of its travel somewhere useless. Reorder is a first-class control because chain order changes the sound: a reverb before a compressor is not the same as after. Carve gets its own block rather than an entry in the add menu, with a picker for the voice track to listen to. It processes this track based on another one, which is how a sidechain control works — it lives on the track that changes, and names the source. * feat(studio): show the Audio FX section on audio tracks Adds `audioFx` to the editing-affordances contract and renders the FX panel in the inspector when an `<audio>` element is selected. The section is audio-only. A `<video>` carries its sound on a separate `<audio>` element, so an FX chain on the video would have nothing to process. Chain and carve settings are written straight back onto the element as serialised attributes, the way colour grading carries its config, so persistence is an ordinary attribute write and needs no new server route. A chain that cannot be parsed renders as empty rather than breaking the panel, and the attribute is left untouched until the user changes something. The collapsed group summarises what is on the track ("2 effects + carve") so the state is visible without expanding it. Wired into PropertyPanelFlat rather than PropertyPanel: STUDIO_FLAT_INSPECTOR_ENABLED defaults to true, so the flat inspector is what actually renders. * refactor(studio): lift audioFxSummary out of PropertyPanelFlat `PropertyPanelFlat.tsx` is 612 lines here against the repo's 600-line cap, so the required File size check is red — the sole reason this PR is blocked. The review says as much: "mechanical fix (~5 min), not a design problem. Code itself is LGTM." Moves `audioFxSummary` to `audioFxSummary.ts`, the same file a later branch creates for it. Deliberately the smallest cut that clears the cap rather than the whole `AudioFxGroup` extraction: every later commit in the stack edits AudioFxGroup, so moving it here would collide with each of them, while almost nothing touches this function. 595 lines. * feat(core,studio): hear the FX chain in preview, and run the carve analysis Splices an element's FX chain into the playback graph so preview stops being silent about effects, and wires the carve button that was previously inert. The chain goes between the decoded source and its gain stage: effects see the raw signal and volume automation rides on their output, matching the order the offline render uses. Since preview and render call the same graph builders, what is heard while scrubbing is what gets written. The splice lives in the transport rather than on the `<audio>` element. The transport plays each track from a decoded AudioBuffer and mutes the element to avoid doubling, so capturing the element with createMediaElementSource would have processed a stream nothing is listening to — it looked like it worked because the call succeeded, and the audio was unchanged. A chain that cannot be built plays dry rather than silencing the track, which is the right failure in preview: the author keeps working and hears the source. The render still refuses, because shipping the dry signal there would be wrong. Carve now analyses for real: it decodes the chosen voice track, ranks its bands and writes the resulting peaking filters onto this track. Generated nodes are tagged `fromCarve`, so re-running replaces the previous carve instead of stacking another set on top of hand-added effects. Known limitation: the graph is built when a source is scheduled, so a knob turned mid-playback takes effect on the next play or seek rather than immediately. Live re-parameterisation needs the transport to hold the handle and forward updates. * fix(studio,core): stop parameter drags from restarting playback Dragging a knob wrote the chain through the persisting attribute path on every input event. That path refreshes the preview, which reloads the composition and reschedules audio — so a single drag reloaded dozens of times and playback stuttered the whole way. Drags now go through `onSetAttributeLive`, the same path colour grading uses for scrubs: it coalesces undo entries and sets `skipRefresh`, so no reload happens. The persisting write fires once, when the gesture ends — pointer-up or blur for a slider, Enter or blur for a typed value. A select commits immediately since there is no drag to wait for. While dragging, the control is driven from local state. Waiting for the value to round-trip through the element attribute made the knob lag behind the pointer. For the change to be audible without a reload, the graph now follows the attribute: the chain installed by the transport observes the element and re-parameterises itself in place, so a value change lands on the next 128-sample quantum. A shape change (effect added, bypassed, pole count) cannot be patched into a running graph, so it still waits for the next schedule rather than cutting the audio mid-play. The regression test drags a slider through several values and asserts the persisting handler is untouched until release. * feat(studio): put the audio FX rack behind its canary Gates the rack on `isCanaryEnabled("audio-fx-rack")`, which is registered at 0% — so the whole 47-PR stack can land without showing anyone a feature that has not been measured yet. The gate sits on the AUTHORING surface and nowhere else. The runtime and the render still honour a `data-fx-chain` already on an element, so a composition written through the skill or by `carve.mjs` keeps its processing rather than going silently dry for anyone outside the cohort. A canary should stage who can REACH a feature, not make an attribute somebody already wrote stop working with no error. Gated at the panel rather than in `resolveEditingSections`: the affordance resolver is a pure function in core describing what an element CAN support, and rollout state is not a property of an `<audio>` tag. Pinned the 0% with a test, and checked it fails at 25 — a ramp should have to break something that says "this ships dark" out loud. One gap, stated rather than papered over: the gate itself has no unit test. I wrote one and deleted it, because `PropertyPanel.test.tsx`'s harness never renders the Audio FX group for its audio fixture even with the gate removed — so the test passed for the wrong reason in the off case and could not pass at all in the on case. A test that cannot fail for the right reason is worse than none. Verifying the gate needs the panel harness to mount that section first, which is its own change. * fix(core): register FX worklets before building nodes that need them An AudioWorkletNode cannot be constructed before its processor is registered — it throws, and the surrounding chain is lost with it. `attachElementFxChain` built the chain first and only then called `ensureAudioFxWorklets`, so every worklet-backed effect (compressor, limiter, gate, bitcrush) threw on construction and the track fell back to dry. Instrumenting the preview showed `hf-compressor: InvalidStateError` with addModule never called at all. When the module has not landed yet the track now plays dry and the graph is swapped in once registration resolves, so the effect arrives a moment late instead of never. Registration is also tracked per context rather than in one module-level promise. A processor registered on one AudioContext does not exist on another, so the shared promise made every context after the first believe it was ready when it was not — the studio's transport owns its own context, which is exactly that case. With the worklets actually running, the compressor's per-sample log10 and pow became real audio-thread work. Samples below the knee have a gain of exactly unity and need neither, so the envelope is now compared in the linear domain and the transcendentals only run for samples that are actually being compressed. * refactor(studio): split the FX node row out of FxSection Clears the health findings the FX stack left behind: the chain-node render callback was a 70-line closure over half of FxSection's state, and the two reorder arrows were the same button written twice. Also drops two exports with no consumers, and registers the audio FX runtime stub as an entry point — it is bundled by file path, so nothing imports it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(core): automation envelope model for audio tracks Adds the data model behind Ableton-style automation lanes: breakpoint envelopes over track volume or one knob of one effect in the track's FX chain, stored on the element as `data-automation`. Times are clip-local, so an envelope travels with the clip when it moves — the clip-envelope model rather than arrangement automation. `sampleAutomationLane` is the single interpolator. The lane drawing, the preview scheduler and the render bake all call it, so the picture and the sound cannot disagree about the curve. Log-scaled parameters interpolate in log space, matching what their own knob already promises. FX nodes gain a stable `id`, minted by count rather than randomly so the document is the same on every machine. Lanes address nodes by id, so reordering a chain never re-points a lane at a different effect, and a lane whose effect was deleted is dropped rather than left to reattach. Also warns when a track carries both a volume lane and a GSAP volume tween, since only the lane is heard and the tween silently does nothing. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * refactor(studio): lift the audio FX group out of PropertyPanelFlat `PropertyPanelFlat.tsx` was 672 lines against the repo's 600-line cap, so the required File size check was red — the sole reason #3014 and #3022 are blocked. Both reviews say the same thing: "mechanical fix, not a design problem. Code itself is LGTM." Moves `AudioFxGroup` and `audioFxSummary` into `propertyPanelAudioFxGroup.tsx`, which is where a later branch puts them anyway — done here so the file is under the cap from the point it first crosses it, rather than ten branches later. 533 lines now. The four audio imports it no longer needs go with it. Not fixed here: three `FxSection carve` tests fail on this branch with "Cannot read properties of undefined (reading 'toFixed')". Confirmed pre-existing by stashing this change and re-running — that is the separate `Test` failure the review also flags. * feat(core): expose the AudioParams behind automatable FX knobs Marks the knobs an automation lane can drive and has each graph builder hand back the AudioParam behind them, so a scheduler can write to a running effect without knowing what the effect is. A knob is not always one AudioParam. A wet/dry mix is two gains moving in opposition, and a knob in milliseconds drives a delay time in seconds, so each target carries the mapping out of the knob's own declared unit. What stays unautomatable is stated where it is decided: a WaveShaper curve, a convolution impulse and a one-pole filter's coefficients are all rebuilt wholesale rather than scheduled, and the four worklet effects take values by postMessage rather than through AudioParams. The registry flag is written by hand, so a test builds every effect and checks the exposure both ways — nothing flagged is missing, nothing exposed is unflagged. A flag that lied would offer a lane that silently did nothing. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(core): play automation envelopes in preview Schedules each lane onto the AudioParams behind its knob using native ramps and value curves. Nothing evaluates the envelope per frame: it is handed to the audio thread once, so it stays sample-accurate however busy the main thread is, and the offline render will schedule it the same way. Timing comes from the transport, so an envelope survives seeking into the middle of a clip, a clip that has not started yet, and a playback rate that compresses clip seconds into context seconds. A straight line is only scheduled as a ramp when nothing bends it — no curvature, a linear parameter scale, and no unit mapping. Log-scaled parameters and mapped ones are sampled instead, since a delay knob in milliseconds and a wet/dry pair moving in opposition are not linear in the parameter they drive. Lanes with nowhere to write are skipped rather than reported: a one-pole filter exposes no frequency param, and the worklet effects expose none at all. Editing an envelope mid-playback re-aims it at the live playhead rather than restarting the track. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix(core): make the volume lane audible in preview The envelope was scheduled onto the transport's gain AudioParam, but the runtime rewrites that gain every tick from `data-volume` and the GSAP-seeked value — so it was erased within a frame. Volume automation was correct in the render and inaudible while previewing. The lane now feeds the per-tick path where the probed volume keyframes already sit, checked ahead of them so the two cannot fight, and the transport no longer schedules volume at all: one mechanism instead of two racing. The cost is honest — in preview the level steps per tick rather than per sample, exactly as the existing keyframe path does. The render still bakes it into the PCM sample-accurately, and FX parameters are still scheduled on their own AudioParams, since nothing rewrites those. Parsed lanes are cached by attribute text: the runtime asks once per tick per track, and parsing there would run the JSON parser 60 times a second for a value that only changes on an edit. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * feat(engine): bake automation envelopes into the render The offline render schedules FX lanes with the same scheduler preview uses, inside the OfflineAudioContext that already runs the same graph builders. The input WAV is the clip's own audio from its first sample, so clip-local time is offline time and the envelope needs no offset. Volume lanes take the existing PCM bake rather than a second mechanism: the lane is converted to keyframes, so a straight fade stays two of them and only a bent segment is sampled — the baker interpolates linearly and would otherwise quietly straighten the curve. A volume lane supersedes keyframes probed from the timeline, which `lint` already warns about. A browser test sweeps a lowpass from below a 2 kHz tone to well above it and measures both ends. Parsing the envelope is not the same as scheduling it, and only running the real thing tells the two apart. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix(core): apply chain edits to the running graph A structural edit — an effect added, removed, bypassed, or a filter's pole count switched — was dropped. `buildFxChain`'s update reports false when the change is not merely new values, and the attribute observer ignored that, so the edit only took hold when the persisting write reloaded the composition. That reload restarted every playing track, which is what was heard as the audio chopping. The graph is now swapped in place: the old effects are detached, the new ones built and connected between the same source and gain, and any lanes re-scheduled onto the new nodes. The source node is never touched, so playback does not restart. A track with no chain is watched too, rather than wired through and forgotten, so adding its first effect is heard the same way. That means the function always returns a disposer instead of null for the empty case. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> * fix(studio): drop the FX panel's dead __testables export Fallow audit flagged it — no test imports the module. * fix(core,studio): clear the remaining Fallow audit findings on the FX panel - Split FxSection's per-node row into FxNodeRow + FxNodeControls so the CRAP score (31.6, threshold 30) splits across two smaller units instead of moving wholesale with one extraction. - Dedupe the repeated "open the add menu, read its items" block in propertyPanelFxSection.test.tsx into openAddMenuItems(). - Merge build-audio-fx-runtime.ts and build-position-edits-render.ts into one build-inline-artifact.ts, config-selected by CLI arg — the two scripts were a byte-for-byte clone save for names. - Exempt canary.test.ts's rawFnv (a deliberate independent reimplementation used to cross-check canaryBucket, per its own docstring) and the property-panel test files' shared renderInto/mount scaffolding (pre-existing across 9 files, 2 outside this stack) in .fallowrc.jsonc, consistent with this file's existing exemptions for the same class of intentional/pre-existing duplication. * fix(ci): allowlist the build-script consolidation in the no-main-deletions guard build-audio-fx-runtime.ts and build-position-edits-render.ts were merged into build-inline-artifact.ts to kill a fallow duplication finding; the deletion guard flagged that as an accidental loss since main still has both originals. * fix(core): dedupe the wet/dry mix math between delayFeedback and chorusLfo Both effect builders set wet.gain to the mix and dry.gain to its complement in identical two-line blocks; fallow kept re-flagging it as a 10-line clone on every unrelated change. Extracted setWetDryMix. * fix(core): remove the build-audio-fx-runtime.ts stray resurrected by a main merge An earlier merge with main brought this deleted file back (git's merge/delete handling on an unchanged-on-one-side file); package.json already points at build-inline-artifact.ts, so it sat unreachable and duplicating that file's config, both of which fallow flagged. --------- Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
Write HTML. Render video. Built for agents.
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HyperFrames is an open-source framework for turning HTML, CSS, media, and seekable animations into deterministic MP4 videos. Use it locally with the CLI, from AI coding agents with skills, or as the rendering core behind hosted authoring workflows.
Quick Start
With an AI coding agent
Install the HyperFrames skills, then describe the video you want:
npx skills add heygen-com/hyperframes --full-depth
The picker opens with nothing pre-selected — the Core Skills group is all you need: the
/hyperframesrouter installs each creation workflow on demand. Agents and non-interactive runs should usenpx hyperframes skills updateinstead — it installs exactly the core set, whereas a non-interactiveskills addwithout--skillinstalls all 19.
--full-depthdoes a full clone of the repo's currentmain. Without it,skills addfetches the skills.sh registry blob, which lagsmainby hours — you'd get an older copy of a skill. (hyperframes skills updatealready installs full-depth.)
Try a prompt like:
Using
/hyperframes, create a 10-second product intro with a fade-in title, a background video, and subtle background music.
The skills teach agents the HyperFrames production loop: plan the video, write valid HTML, wire seekable animations, add media, lint, preview, and render. They work with Claude Code, Cursor, Gemini CLI, Codex, and other coding agents that support skills.
Skills
HyperFrames ships 19 skills agents load on demand. Read /hyperframes first — it's the router and capability map; it picks a workflow for any "make me a…" request — video, deck, or composition port — and points to the domain skills below.
Default to the core set — the router installs each creation workflow on demand. npx hyperframes skills update installs exactly that from anywhere; the interactive picker (npx skills add heygen-com/hyperframes --full-depth) lists it as the "Core Skills" group, nothing pre-selected. The picker is interactive-only — a non-interactive or agent run without --skill installs all 19. Use npx skills add heygen-com/hyperframes --all --full-depth to install all 19 deliberately (skips the picker), or npx skills add heygen-com/hyperframes --skill <name> --full-depth for just one (bare name, no leading /). Keep --full-depth — it installs the current main; without it skills add fetches the skills.sh blob, which lags by hours.
Installs stay lean after that: npx hyperframes init keeps the core set fresh (the router, the hyperframes-* domain skills, and media-use — plus whatever is already installed; /figma stays on demand) and never expands a partial install; the creation workflows install on demand — the router runs npx hyperframes skills update <workflow> before entering one. Nothing re-pulls the full set behind your back.
Upload to Codex
Build the upload-ready Codex plugin archive from the committed HEAD version of the manifest, brand assets, and skills:
bun run package:codex-plugin
This writes dist/hyperframes-plugin.zip with a hyperframes/ root folder and fails if the archive exceeds Codex's 100 MB upload limit.
Router
| Skill | Use when |
|---|---|
/hyperframes |
Read first for any request to make / create / edit / animate / render a video, animation, or motion graphic. Capability map for the domain skills, the intent layer that confirms every creation brief up front, and intent router for the creation workflows below. |
Creation workflows
| Skill | Use when |
|---|---|
/product-launch-video |
Any website — marketing / launching / promoting a product (from its URL, a brief, or a script), or a site tour / showcase / social clip featuring the site's own visuals. Up to ~3 min (sweet spot 30-90s). |
/faceless-explainer |
Explaining a topic / concept from arbitrary text — no product, no URL, no website capture; every visual is LLM-invented (typography / abstract / diagram / data-viz). |
/pr-to-video |
A GitHub pull request (PR URL, owner/repo#N ref, or "this PR") → changelog / feature-reveal / fix / refactor explainer, read via the gh CLI. |
/embedded-captions |
Adding captions / subtitles to an existing talking-head video (footage untouched) — verbatim rail, embedded climax behind the subject, or pure-cinematic embed. |
/talking-head-recut |
Packaging an existing talking-head / interview / podcast video with designed graphic overlays — lower-thirds, data callouts, kinetic titles, pull-quotes, side panels, PiP. |
/motion-graphics |
A short, unnarrated, design-led motion graphic (~under 10s) — kinetic type, stat / chart hit, logo sting, lower-third, animated tweet / headline. MP4 or transparent overlay. |
/music-to-video |
A music track (audio file, video to pull audio from, or one generated from a mood brief) → a beat-synced video — lyric, slideshow, or kinetic promo; music drives pacing. |
/slideshow |
A presentation / pitch deck / interactive deck — discrete slides, fragment reveals, branching, hotspot navigation, presenter mode. Output is a navigable deck, not a rendered video. |
/general-video |
Anything else — longer or multi-scene pieces, brand / sizzle reel, title card, static loop, freeform composition. Input- and length-agnostic fallback, and the home of companion mode (co-create with the full toolbox). |
/remotion-to-hyperframes |
Porting an existing Remotion (React) composition's source to HyperFrames HTML. One-way migration, not creation. |
Domain skills (loaded on demand)
Atomic capabilities the creation workflows compose against — pull one when you need that specific layer.
| Skill | Covers |
|---|---|
/hyperframes-core |
The composition contract — data-* timing attributes, class="clip", tracks, sub-compositions, variables, framework-owned media playback, determinism rules. |
/hyperframes-animation |
All animation knowledge — atomic motion rules, scene blueprints, transitions, runtime adapters (GSAP / Lottie / Three.js / Anime.js / CSS / WAAPI / TypeGPU). |
/hyperframes-keyframes |
Seek-safe keyframe authoring across runtimes — GSAP timelines, CSS keyframes, Anime.js, WAAPI, FLIP, paths, masks, SVG morph/draw, 3D depth — plus hyperframes keyframes diagnostics for rendered motion. |
/hyperframes-creative |
Non-animation creative direction — frame.md / design.md, palettes, typography, narration, beat planning, audio-reactive visuals, composition patterns. |
/media-use |
The media OS — resolve any media need (BGM, SFX, image, icon, logo, voice, color grade, LUT) into a frozen local file or paste-ready block + ledger record, generate via TTS/music/image models when the catalog misses, transcribe, caption, remove backgrounds, and reuse assets across projects. One shared audio engine + manifest tracking. |
/hyperframes-cli |
CLI dev loop — init, lint, check, snapshot, preview, render, publish, doctor, plus HeyGen-hosted cloud rendering (cloud render) and AWS Lambda rendering (lambda deploy / render / progress). |
/hyperframes-registry |
Install and wire registry blocks and components into compositions via hyperframes add. Authoring a new block or component to contribute upstream. |
/figma |
Import Figma assets, tokens, components, and storyboard sections → reconstructed motion (frames read as states, not slides) (REST/CLI) plus Motion animations (MCP) and shaders (MCP source / native export) into a composition. |
For visual design handoff workflows, see the Claude Design guide and Open Design guide.
Manually with the CLI
npx hyperframes init my-video
cd my-video
npx hyperframes preview # preview in browser with live reload
npx hyperframes render # render to MP4
Requirements: Node.js 22+, FFmpeg
What You Can Build
Need ideas? Browse the Showcase for finished videos you can watch, read, run, and remix.
- Product launch videos and feature announcements
- PR walkthroughs with animated code diffs, narration, and captions
- Data visualizations, chart races, and map animations
- Social videos with kinetic captions, overlays, and music
- Docs-to-video, PDF-to-video, and site-tour explainers
- Reusable motion graphics for automated content pipelines
Frame.md
frame.md — your design system, ready for video.
Every brand has a design.md. None of them were written for a camera. frame.md is the missing translation layer: it takes your web-context design spec and inverts it for the frame — the same tokens, the same rules, but rewritten so an AI agent can compose a promo video without guessing at scale or reaching for web chrome.
The output is a DESIGN.md superset your whole toolchain can read. Atoms stay sacred. Composition stays free. Numbers come from the script.
Biennale Yellow |
BlockFrame |
Blue Professional |
Bold Poster |
Broadside |
Capsule |
Cartesian |
Cobalt Grid |
Coral |
Creative Mode |
Browse and remix them all at hyperframes.dev/design.
How It Works
Define a video as HTML. Add data attributes for timing and tracks. Use GSAP, CSS, Lottie, Three.js, Anime.js, WAAPI, or your own frame adapter for seekable animation.
<div id="stage" data-composition-id="launch" data-start="0" data-width="1920" data-height="1080">
<video
class="clip"
data-start="0"
data-duration="6"
data-track-index="0"
src="intro.mp4"
muted
playsinline
></video>
<h1 id="title" class="clip" data-start="1" data-duration="4" data-track-index="1">Launch day</h1>
<audio
data-start="0"
data-duration="6"
data-track-index="2"
data-volume="0.5"
src="music.wav"
></audio>
<script src="https://cdn.jsdelivr.net/npm/gsap@3/dist/gsap.min.js"></script>
<script>
const tl = gsap.timeline({ paused: true });
tl.from("#title", { opacity: 0, y: 40, duration: 0.8 }, 1);
window.__timelines = window.__timelines || {};
window.__timelines.launch = tl;
</script>
</div>
Preview instantly in the browser. Render locally or in Docker. The renderer seeks each frame in headless Chrome and encodes the result with FFmpeg, so the same input produces the same video.
HyperFrames Stack
HyperFrames is the open-source rendering engine, plus a growing set of tools around HTML-native video creation.
| Piece | Status | What it does |
|---|---|---|
| CLI | Available | Scaffold, preview, lint, inspect, and render local video projects |
| Core / Engine / Producer | Available | Parse compositions, drive headless Chrome, encode video, and mix audio |
| Catalog | Available | Reusable blocks and components for transitions, overlays, captions, charts, maps, and effects |
| Agent skills | Available | Teach coding agents the video-production patterns that generic web docs miss |
| Studio | Available, evolving | Browser surface for previewing and editing compositions |
| AWS Lambda rendering | Available | Deploy a distributed render stack and drive renders from your laptop or CI |
| hyperframes.dev | Available | Community playground for previewing, iterating, sharing, and rendering HTML-native video projects |
| frame.md | Available | Invert your design system for the camera — a DESIGN.md superset an agent can compose video from |
Catalog
Install ready-to-use blocks and components:
npx hyperframes add flash-through-white # shader transition
npx hyperframes add instagram-follow # social overlay
npx hyperframes add data-chart # animated chart
Browse the catalog at hyperframes.heygen.com/catalog.
Why HyperFrames?
- HTML-native: compositions are HTML files with data attributes. No React requirement, no proprietary timeline format.
- Agent-friendly: agents already write HTML, and the CLI is non-interactive by default.
- Deterministic: same input, same frames, same output. Built for CI, regression tests, and automated rendering.
- No build step: an
index.htmlcomposition plays as-is and can be previewed directly in the browser. - Adapter-based animation: bring GSAP, CSS animations, Lottie, Three.js, Anime.js, WAAPI, or a custom runtime.
- Open source: Apache 2.0 license, with no per-render fees or commercial-use thresholds.
HyperFrames vs Remotion
HyperFrames is inspired by Remotion. Both tools render video with headless Chrome and FFmpeg. The main difference is the authoring model: Remotion's bet is React components; HyperFrames' bet is plain HTML that humans and agents can both write easily.
| HyperFrames | Remotion | |
|---|---|---|
| Authoring | HTML + CSS + seekable animation | React components |
| Build step | None; index.html plays as-is |
Bundler required |
| Agent handoff | Plain HTML files | JSX / React project |
| Library-clock animations | Seekable, frame-accurate via adapters | Wall-clock animation patterns need care |
| Distributed rendering | Local and AWS Lambda render paths | Remotion Lambda, mature cloud renderer |
| License | Apache 2.0 | Source-available Remotion License |
Read the full comparison in the HyperFrames vs Remotion guide.
Documentation
Full documentation: hyperframes.heygen.com/introduction
Packages
| Package | Description |
|---|---|
hyperframes |
CLI for creating, previewing, linting, and rendering compositions |
@hyperframes/core |
Types, parsers, generators, linter, runtime, and frame adapters |
@hyperframes/engine |
Seekable page-to-video capture engine using Puppeteer and FFmpeg |
@hyperframes/producer |
Full rendering pipeline for capture, encode, and audio mix |
@hyperframes/studio |
Browser-based composition editor UI |
@hyperframes/player |
Embeddable <hyperframes-player> web component |
@hyperframes/shader-transitions |
WebGL shader transitions for compositions |
@hyperframes/aws-lambda |
AWS Lambda SDK and deployment surface for distributed renders |
Community
HyperFrames is used in production at HeyGen, with community examples from teams like tldraw, TanStack, and others in ADOPTERS.md. Open a PR if your team is using HyperFrames.
- Questions and ideas: Discord
- Bugs and feature requests: GitHub Issues
- User research: Book a casual 30-minute conversation with the HyperFrames team — no preparation or sales pitch
- Security reports: SECURITY.md
- Contributions: CONTRIBUTING.md
Development Note
The repo uses Git LFS for golden regression-test baselines under packages/producer/tests/**/output.mp4 (about 240 MB of .mp4 files). If you're cloning the full repo for development, install Git LFS first:
# macOS
brew install git-lfs
# Ubuntu / Debian
sudo apt install git-lfs
# Windows
winget install GitHub.GitLFS
# Then, once per machine
git lfs install
If you only need source files, you can skip LFS content:
GIT_LFS_SKIP_SMUDGE=1 git clone https://github.com/heygen-com/hyperframes.git