Slideshow authoring contract

A HyperFrames slideshow is a normal HyperFrames composition — scenes, clips, GSAP timelines — with one extra ingredient: a JSON island that declares which scenes are slides and how they connect. The player's SlideshowController reads the island and turns the continuous GSAP timeline into a discrete, navigable deck.

Read /hyperframes-core first for the base composition contract (clips, tracks, data-* attributes, determinism rules). This skill covers only what is new: the island schema, slide writing rules, fragments, branching, validation, and the wrapping component.

---

The two pieces

1. Scenes — declared the normal way

Every slide is backed by a scene. Declare scenes with data-composition-id, data-start, data-duration, and data-label:

<div
  data-composition-id="problem"
  data-start="0"
  data-duration="8"
  data-label="The problem"
  data-width="1920"
  data-height="1080"
>
  <!-- clips go here -->
</div>

Branch slides (reachable only via a hotspot, excluded from the main line) are declared exactly the same way — they just appear only in a slideSequences entry in the island, not in the main slides array.

2. The JSON island — one script block per composition

Add exactly one <script type="application/hyperframes-slideshow+json"> block to the composition HTML. It holds all slideshow metadata:

<script type="application/hyperframes-slideshow+json">
  {
    "slides": [...],
    "slideSequences": [...]
  }
</script>

The island is the single source of truth for slide order, notes, fragment hold-points, hotspots, and branch sequences. Keep it near the top of the <body>, before the scene divs, so it is easy to find.

---

Schema

`SlideshowManifest` (the top-level island object)

{
  "slides": [
    /* SlideRef[] — the main line, in order */
  ],
  "slideSequences": [
    /* SlideSequence[] — off-line branch sequences */
  ]
}

`SlideRef`

{
  "sceneId": "problem",
  "notes": "Lead with the pain, not the company.",
  "fragments": [3.5, 5.2, 7.0],
  "hotspots": [
    /* SlideHotspot[] */
  ],

  "ttsScript": null,
  "ttsAudioUrl": null,
  "ttsDurationMs": null
}

Field	Required	Notes
`sceneId`	yes	Must match a scene's `data-composition-id` exactly. The lint rule resolves both `data-composition-id` and `.clip[id]`.
`notes`	no	Presenter-only text. Never shown to the audience.
`fragments`	no	Array of times (seconds) within the slide's `[start, end]` range — see Fragments below.
`hotspots`	no	Interactive overlays that trigger a branch — see Branching below.
`startTime`	no	Optional. Override the matched scene's time bounds; defaults to the scene's start/end.
`endTime`	no	Optional. Override the matched scene's time bounds; defaults to the scene's start/end.
`ttsScript`, `ttsAudioUrl`, `ttsDurationMs`	no	Reserved. Schema fields exist but TTS playback is not yet wired. Omit unless you are pre-populating for a future build.

`SlideHotspot`

{
  "id": "h1",
  "label": "How did we calculate this?",
  "target": "market-deep-dive",
  "region": { "x": 60, "y": 10, "w": 35, "h": 20 }
}

Field	Required	Notes
`id`	yes	Unique within the slide.
`label`	yes	Tooltip / button text shown to the audience.
`target`	yes	Must match a `SlideSequence.id` in `slideSequences`.
`region`	no	Percentage-of-slide bounding box: `{x, y, w, h}` in `0–100`. Omit to render the hotspot as a full-slide labeled button instead.

`SlideSequence`

{
  "id": "market-deep-dive",
  "label": "Market sizing methodology",
  "slides": [{ "sceneId": "mkt-1" }, { "sceneId": "mkt-2" }]
}

slides inside a sequence uses the same SlideRef shape as the main line. Fragments and nested hotspots are allowed.

---

Slide writing rules

These are hard constraints, not suggestions. A slide that violates them will be outright replaced when a reviewer sees it.

Headline is a complete-sentence claim, not a label. Write "SMBs spend 14 hours/week on manual scheduling" not "Scheduling problem". The sentence should stand alone if the visual is ignored.
One idea + one visual per slide. If you are tempted to add a second bullet cluster or a second chart, split the slide.
Lead with the punchline. The strongest point goes first — on the slide and in the deck order. Investors read left-to-right, top-to-bottom, and they stop.
Bottom-up market sizing only. Never write "$50B TAM" without showing the math. Build from unit economics up: accounts × ACV, or transactions × take-rate.
Font minimum 30pt equivalent. At 1920×1080, a headline is 72–96px; body copy is 48px. Never go below 40px for any text the audience must read.

---

Fragments: reveal hold-points within a slide

A fragment is a time (in seconds) within a slide's [start, end] range where the controller pauses before the next reveal.

How it works:

Player enters the slide — seeks to start, then plays.
Controller pauses at fragments[0]. The first element's GSAP entrance has just landed.
User presses Next (or →) — plays to fragments[1], pauses again.
After the last fragment, Next plays to slide.end and holds.
Next again advances to the next slide.

Fragment times must be strictly inside [start, end]. The lint rule rejects fragments outside that range.

Fragment times are absolute composition-timeline positions — the same coordinate space as data-start — not offsets relative to the scene's start.

Each fragment is a play-to-and-hold, not a seek jump — so every element that enters between the previous hold-point and this one plays its GSAP entrance animation. Design the clip entrance animations to work as sequential reveals.

---

Branching: hotspots and slide sequences

Branch slides are real scenes in the same composition timeline. They are listed only under slideSequences and are excluded from main-line navigation — the player never visits them unless a hotspot fires.

Navigation model:

Clicking a hotspot pushes {sequenceId, slideIndex: 0} onto the nav stack and enters the branch's first slide.
back() pops the stack and returns to the exact parent slide (the one that held the hotspot).
backToMain() clears the entire stack and returns to the root slide.
Breadcrumb renders from the stack: Main deck › Market sizing methodology › Slide 2.
The slide counter inside a branch is scoped to that sequence (1 of 2, not the main-deck total).

What to avoid:

Do not add branch scene IDs to the main slides array. They must appear only inside a slideSequences entry. The lint rule flags overlap.
Branch scenes are included in the continuous timeline, so a naive linear video export would include them. Export reads main-line slides only (deferred; flagged in the spec).

---

Worked example: 3-slide deck with fragments and a branch

Scene HTML (skeleton)

<body style="margin: 0">
  <script type="application/hyperframes-slideshow+json">
    {
      "slides": [
        {
          "sceneId": "hook",
          "notes": "Open with the stat. Pause on the $40B number."
        },
        {
          "sceneId": "problem",
          "notes": "Walk through each pain point one at a time.",
          "fragments": [11.0, 15.0],
          "hotspots": [
            {
              "id": "h1",
              "label": "Where does the $40B figure come from?",
              "target": "market-detail",
              "region": { "x": 55, "y": 60, "w": 40, "h": 20 }
            }
          ]
        },
        {
          "sceneId": "solution",
          "notes": "One sentence: what we do and who it is for."
        }
      ],
      "slideSequences": [
        {
          "id": "market-detail",
          "label": "Market sizing methodology",
          "slides": [{ "sceneId": "mkt-math", "notes": "Bottom-up: 2.3M SMBs × $17k ACV." }]
        }
      ]
    }
  </script>

  <!-- Slide 1 — hook -->
  <div
    data-composition-id="hook"
    data-start="0"
    data-duration="6"
    data-label="The hook"
    data-width="1920"
    data-height="1080"
    style="position: relative; width: 1920px; height: 1080px; overflow: hidden; background: #0a0a0a"
  >
    <section
      class="clip"
      data-start="0"
      data-duration="6"
      data-track-index="1"
      style="position: absolute; inset: 0; display: grid; place-items: center"
    >
      <h1 id="hook-headline" style="font-size: 80px; color: #fff; font-family: sans-serif">
        SMBs lose $40B/year to manual scheduling
      </h1>
    </section>
  </div>

  <!-- Slide 2 — problem (3 fragments) -->
  <div
    data-composition-id="problem"
    data-start="6"
    data-duration="15"
    data-label="The problem"
    data-width="1920"
    data-height="1080"
    style="position: relative; width: 1920px; height: 1080px; overflow: hidden; background: #0a0a0a"
  >
    <section
      class="clip"
      data-start="6"
      data-duration="15"
      data-track-index="1"
      style="position: absolute; inset: 0; padding: 120px 160px; box-sizing: border-box"
    >
      <h2 id="pain-headline" style="font-size: 64px; color: #fff; font-family: sans-serif">
        Three gaps operators can not close
      </h2>
      <p id="pain-1" style="font-size: 48px; color: #ccc; opacity: 0; font-family: sans-serif">
        No-shows cost 23% of booked revenue
      </p>
      <p id="pain-2" style="font-size: 48px; color: #ccc; opacity: 0; font-family: sans-serif">
        Manual reminders take 4h/week per staff
      </p>
      <p id="pain-3" style="font-size: 48px; color: #ccc; opacity: 0; font-family: sans-serif">
        Rescheduling friction drives 40% churn
      </p>
    </section>
  </div>

  <!-- Slide 3 — solution -->
  <div
    data-composition-id="solution"
    data-start="21"
    data-duration="8"
    data-label="The solution"
    data-width="1920"
    data-height="1080"
    style="position: relative; width: 1920px; height: 1080px; overflow: hidden; background: #0a0a0a"
  >
    <section
      class="clip"
      data-start="21"
      data-duration="8"
      data-track-index="1"
      style="position: absolute; inset: 0; display: grid; place-items: center"
    >
      <h2 id="solution-headline" style="font-size: 72px; color: #fff; font-family: sans-serif">
        Acme automates scheduling for service SMBs — no-shows down 80% in 90 days
      </h2>
    </section>
  </div>

  <!-- Branch slide — excluded from main line -->
  <div
    data-composition-id="mkt-math"
    data-start="29"
    data-duration="7"
    data-label="Market math"
    data-width="1920"
    data-height="1080"
    style="position: relative; width: 1920px; height: 1080px; overflow: hidden; background: #111"
  >
    <section
      class="clip"
      data-start="29"
      data-duration="7"
      data-track-index="1"
      style="position: absolute; inset: 0; display: grid; place-items: center"
    >
      <p id="mkt-formula" style="font-size: 56px; color: #fff; font-family: sans-serif">
        2.3M SMBs × $17k ACV = $39B serviceable market
      </p>
    </section>
  </div>

  <script>
    window.__timelines = window.__timelines || {};

    // Slide 2 fragment entrance animations
    gsap.registerPlugin(); // load any plugins before use

    const tl = gsap.timeline({ paused: true });
    window.__timelines["problem"] = tl;

    // Insert positions are absolute composition-timeline times (same as data-start / fragment values).
    tl.from("#pain-1", { opacity: 0, y: 20, duration: 0.4 }, 11.0);
    tl.from("#pain-2", { opacity: 0, y: 20, duration: 0.4 }, 15.0);
    // pain-3 lands at end of slide
    tl.from("#pain-3", { opacity: 0, y: 20, duration: 0.4 }, 13.0);
  </script>
</body>

Key points in the example

The island sceneId values ("hook", "problem", "solution", "mkt-math") exactly match data-composition-id values on scene divs.
mkt-math appears only in slideSequences — it is never in the top-level slides array.
Fragment times (11.0, 15.0) are within the problem scene's [6, 21] range (times are absolute composition-timeline positions).
The hotspot region (x: 55, y: 60, w: 40, h: 20) positions the clickable area in the lower-right quadrant of the problem slide.
GSAP timelines are registered on window.__timelines and are paused — the HyperFrames engine drives playback; do not call .play() at construction time.

---

Wrapping component

Wrap the composition in <hyperframes-slideshow> around <hyperframes-player> in any embedding context:

<hyperframes-slideshow>
  <hyperframes-player src="deck.html"></hyperframes-player>
</hyperframes-slideshow>

<hyperframes-slideshow> provides the navigation chrome (Prev / Next buttons, progress dots, breadcrumb, counter), keyboard handling (← / → and Space / Backspace), touch swipe, and hotspot overlays.

Presenter mode: the Present button calls window.open('?mode=audience') for a fullscreen audience window; the originating tab becomes the presenter view (current slide reduced, next-slide preview, notes, elapsed timer). Both windows sync via BroadcastChannel('hf-slideshow').

---

Running a slideshow standalone (interim)

The durable answer is engine-hosted: hyperframes preview --slideshow / studio present mode will host the composition over the real HyperFrames engine, which drives seek-timelines, owns the gesture frame, and reads the island from the composition. That path is coming; prefer it once it ships.

Until then, standalone demos (a composition opened via the bare player bundle in a browser, without the engine) require workarounds for four gaps: the player does not drive GSAP seek-timelines, the island must be duplicated into the wrapper, audio must live in the parent frame, and animations must be self-driving. These patterns are documented in:

skills/slideshow/references/standalone-harness.md

Do not treat the patterns there as the blessed model — they exist only to bridge the gap until the engine-hosted path lands.

---

Validation

After authoring or editing a slideshow composition, run:

npx hyperframes lint

The slideshow lint rule checks:

Every slide.sceneId resolves to an existing scene (by data-composition-id).
Every hotspot.target references a defined slideSequence id.
Fragment times fall within each slide's [start, end] range.
No two main-line slides overlap in time.

Fix all violations before previewing. A composition that fails lint will not parse correctly in the player.