Merge pull request 'Ask iOS for the playback audio session on a page with a video' (#14) from video-audio-session-on-ios into main

Reviewed-on: #14

.gitea/workflows/publish.yml

@@ -157,19 +157,26 @@ jobs:
     # it is a candidate for, so there is nothing yet to move past.
     if: github.ref_type == 'tag' && !contains(github.ref_name, '-')
     runs-on: ubuntu-latest
+    # npm does the bump, so this one job wants node. A job in a container is
+    # given `sh -e {0}` as its shell rather than the bash the runner's own jobs
+    # get, and dash has neither `pipefail` nor the `10#` below — which failed
+    # the first line of the first step the one time this ran. node:22 is Debian
+    # and carries bash, so asking for it keeps these scripts the same as the
+    # ones in the job above.
     container:
       image: node:22
+    defaults:
+      run:
+        shell: bash
     steps:
       # The tag names a commit in main's history, but the bump belongs on the
-      # branch, so this checks out main rather than the tag.
+      # branch, so this checks out main rather than the tag. The full history
+      # because a shallow clone cannot reliably push a branch back.
       - uses: actions/checkout@v4
         with:
           ref: main
-          # The task token can push only if the instance allows Actions to
+          fetch-depth: 0
-          # write to the repository. Where it does not, set VERSION_BUMP_TOKEN
+          token: ${{ secrets.GITHUB_TOKEN }}
-          # to a personal access token with write access and it is used
-          # instead.
-          token: ${{ secrets.VERSION_BUMP_TOKEN || secrets.GITEA_TOKEN }}
 
       - name: Work out the next patch version
         id: next
@@ -211,30 +218,59 @@ jobs:
           echo "changed=true" >> "$GITHUB_OUTPUT"
           echo "package.json ${current} -> ${NEXT}"
 
-      - name: Commit it to main
+      # The bump arrives as a pull request rather than as a commit straight to
+      # main. Pushing a branch asks nothing of the task token beyond ordinary
+      # write access, so nothing here depends on being allowed past whatever
+      # protects main; and the pull request puts the changed package.json
+      # through the build before it lands. Since main is never pushed, the
+      # `[skip ci]` that would otherwise be needed to stop this rebuilding the
+      # image just published is not.
+      - name: Open a pull request for it
         if: steps.bump.outputs.changed == 'true'
         env:
           NEXT: ${{ steps.next.outputs.next }}
+          RELEASED: ${{ github.ref_name }}
+          TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           set -euo pipefail
 
+          branch="release/bump-${NEXT}"
+
           # A name that is not a person, and a reserved address that can never
           # resolve to one. Nothing here names the instance it runs on.
           git config user.name 'Release bot'
           git config user.email '[email protected]'
 
+          git checkout -b "${branch}"
           git add package.json package-lock.json
-          # `[skip ci]` because this commit is a number and nothing else:
+          git commit -m "Set the working version to ${NEXT}"
-          # without it the push to main starts another build of the very image
+          git push origin "${branch}"
-          # that was just published.
-          git commit -m "Set the working version to ${NEXT} [skip ci]"
 
-          if ! git push origin HEAD:main; then
+          # node rather than jq to build the request body: jq is not in this
-            echo >&2
+          # image, and node is the one thing that certainly is.
-            echo "Could not push the version bump to main. Either the Actions" >&2
+          payload="$(BRANCH="${branch}" node -e 'process.stdout.write(JSON.stringify({
-            echo "token has no write access to this repository, or main is" >&2
+            head: process.env.BRANCH,
-            echo "protected against direct pushes. Set VERSION_BUMP_TOKEN to a" >&2
+            base: "main",
-            echo "token that may push to main, or allow that token past the" >&2
+            title: `Set the working version to ${process.env.NEXT}`,
-            echo "branch protection." >&2
+            body: `${process.env.RELEASED} has shipped, so the tree was left on a version that is published and immutable. This moves it on to ${process.env.NEXT}, which is deliberately not a version that exists.`,
-            exit 1
+          }))')"
-          fi
+
+          api="${GITHUB_SERVER_URL}/api/v1/repos/${GITHUB_REPOSITORY}"
+          response="$(mktemp)"
+          code="$(curl -sS -o "${response}" -w '%{http_code}' \
+            -X POST "${api}/pulls" \
+            -H "Authorization: token ${TOKEN}" \
+            -H 'Content-Type: application/json' \
+            -d "${payload}")"
+
+          case "${code}" in
+            201) echo "Opened ${branch} against main." ;;
+            # A release re-run that got this far: the branch and its pull
+            # request are already there, which is the state we wanted anyway.
+            409) echo "A pull request for ${branch} is already open." ;;
+            *)
+              echo "Could not open the pull request (HTTP ${code}):" >&2
+              cat "${response}" >&2
+              exit 1
+              ;;
+          esac

CLAUDE.md

@@ -96,6 +96,15 @@ Things worth knowing before editing:
   `src/media/registry.ts` and served from `/m/<id>` with the `Referer`/`Cookie` the CDN
   demands. `Range` is forwarded — without it the native video scrubber cannot seek.
   The exception is HLS (`direct: true`), because proxying would mean rewriting playlists.
+- **A video is sized by its poster**, not by the ratio the renderer puts on it. A
+  `<video>` with no data has a natural size of 300x150, and WebKit sizes it from that —
+  so one with no poster of its own gets an empty SVG of the right shape as a stand-in,
+  without which a portrait video sits in a squat landscape box until you press play.
+- **A page with a video claims the `playback` audio session** (`public/app.js`). iOS
+  hands inline video the ambient session, which the Ring/Silent switch mutes, so
+  without this the video plays and says nothing until it goes fullscreen — and the
+  report that arrives is "this one platform has no sound". The session only activates
+  once something plays, so declaring it costs nothing on a page nobody presses play on.
 - **Never a bare error page.** A failed resolve renders a card carrying the platform, the
   original URL and the copy button. A broken adapter must still leave the link one tap
   away.
@@ -144,16 +153,22 @@ Things worth knowing before editing:
   Video: `fallback_url` is the *video track alone* whenever `has_audio` is true, so a
   post with sound has to use `hls_url`, direct and unproxied; a silent one gets the
   proxied MP4. `scrubber_media_url` is not a poster — it is a second MP4 for the
-  timeline thumbnails, and the still is in `preview.images`. A gallery's pictures are in
+  timeline thumbnails, and the still is in `preview.images` — which belongs to both
-  `media_metadata`, keyed and unordered; their order is only in `gallery_data`. Comment
+  forms: the HLS one used to go without, and showed an empty box where a silent post
+  showed a frame. A gallery's pictures are in `media_metadata`, keyed and unordered;
+  their order is only in `gallery_data`. Comment
   bodies are Markdown, rendered by `src/render/markdown.ts` — escape first, then put
   back the constructs we chose to support, never `body_html`. An image in a comment is
   written as a token rather than an address — `![gif](giphy|Ve7wX45)`,
-  `![img](emote|t5_2th52|4358)`, `![img](jo8gf0ca92zd1)` — and in every case the token is
+  `![img](emote|t5_2th52|4358)`, `![img](jo8gf0ca92zd1)` — and the token is usually a key
-  a key in that same comment's own `media_metadata`, so `resolveInlineImages` is one
+  in that same comment's own `media_metadata`, so `resolveInlineImages` is one lookup
-  lookup rather than three special cases. A bare `preview.redd.it` address pasted into a
+  rather than three special cases. Usually: plenty of comments carry a Giphy token and
-  comment is in there too, keyed by the id inside the URL. Prefer `s.gif` over `s.mp4`
+  no `media_metadata` at all, and Giphy is the one of the three whose id means something
-  for an animated one: a GIF moves in an `<img>` and an MP4 needs a player. An address
+  off Reddit, so that token alone falls back to `i.giphy.com/media/<id>/giphy.gif`. A
+  variant name after the id is dropped — Giphy does not serve every variant of every
+  gif. A bare `preview.redd.it` address pasted into a comment is in there too, keyed by
+  the id inside the URL. Prefer `s.gif` over `s.mp4` for an animated one: a GIF moves in
+  an `<img>` and an MP4 needs a player. An address
   typed without a scheme counts as well, but only when it ends in an image extension —
   the rule wants a host, a path *and* that extension, because comments are full of
   dotted, slashed prose that must not turn into links.
@@ -183,6 +198,10 @@ Login walls are not passed through — those need an account and cannot be solve
 - **No ESLint** — `typescript-eslint` does not support TS 7 yet. `npm run typecheck` is
   the lint step.
 - Tests are `node:test` against captured fixtures. No network in the test suite.
+- `public/` is served as-is to the browser, so what is in there is plain JS, not TS.
+  `public/browsers.js` — the per-browser URL schemes behind the "open in" picker — is
+  a module rather than more of `app.js` so a test can import it; that is what `allowJs`
+  in `tsconfig.json` is for.
 - Comments explain *why*, especially where the code looks odd because a platform is odd.
   Match that; do not add narration of what the next line does.
 - Post text comes from strangers: everything goes through the `html` tagged template or
@@ -210,16 +229,22 @@ The registry comes from the `REGISTRY` repository variable, the image name from
 `IMAGE_NAME` or the repository name, and credentials from `REGISTRY_USER` and the
 `REGISTRY_TOKEN` secret. Nothing about any particular deployment is committed here.
 
-A release also moves `package.json` on to the next patch version, committed to main by
+A release also moves `package.json` on to the next patch version, opened as a pull
-the `bump` job — so the number in the tree is never one that has already shipped and
+request by the `bump` job — so the number in the tree is never one that has already
-been made immutable. It lives in `publish.yml` rather than a workflow of its own so it
+shipped and been made immutable. It lives in `publish.yml` rather than a workflow of its
-can say `needs: build`: a version that failed to publish has not been released, and
+own so it can say `needs: build`: a version that failed to publish has not been
-bumping past it would claim otherwise. Prereleases are skipped, being candidates for a
+released, and bumping past it would claim otherwise. Prereleases are skipped, being
-version that has not shipped. The bump goes through `npm version` rather than an edit in
+candidates for a version that has not shipped. The bump goes through `npm version`
-place, because the version is in the lockfile too, in more than one place, and the two
+rather than an edit in place, because the version is in the lockfile too, in more than
-have to agree. The commit carries `[skip ci]`, or pushing it would rebuild the image
+one place, and the two have to agree.
-that was just published. Pushing to main needs a token with write access —
+
-`VERSION_BUMP_TOKEN` overrides the task token where that one cannot.
+It arrives as a pull request rather than as a commit straight to main: pushing a branch
+asks nothing of the task token beyond ordinary write access, so it does not matter what
+protects main, and the changed `package.json` goes through a build before it lands.
+Nothing pushes to main, so no `[skip ci]` is needed to stop the bump rebuilding the
+image just published. The job is the only one that runs in a container (`node:22`, for
+npm), and a job in a container is handed `sh`, not bash — hence the explicit
+`shell: bash`, without which `set -o pipefail` fails the first line of the first step.
 
 Two things any deployment has to get right, both learned the hard way:
 

README.md

@@ -73,6 +73,35 @@ button hands back.
 `/` serves these rules with the live hostname already filled in, if you'd rather copy
 them from there.
 
+## Opening the original
+
+The rules are indiscriminate, which is the point — but that catches the way back out
+too. Tapping "Open on Instagram" in the browser the rules are installed in redirects
+straight back here, so the one button meant to get you to the app is the one button that
+cannot.
+
+The way past it is to hand the address to a *different* browser, by its own URL scheme.
+`/` has a picker for which one:
+
+| Browser | macOS | iOS |
+| --- | --- | --- |
+| Chrome | `googlechromes://…` | `googlechromes://…` |
+| Edge | `microsoft-edge:https://…` | `microsoft-edge-https://…` |
+| Orion | `orion://open-url?url=…` | `orion://open-url?url=…` |
+| Firefox | — | `firefox://open-url?url=…` |
+
+Firefox on macOS registers no scheme, so it is not offered there; nor is Safari itself,
+which is the browser being escaped. The choice is kept in that browser's own
+`localStorage` — not a cookie and not synced, because "which browser is installed" is a
+fact about the device, not about you, and the phone's answer is not the Mac's.
+
+Until a browser is chosen there is no "Open on …" button at all — the plain address is
+the one thing it must not offer, since following it only comes back here. The markup
+carries that address anyway, hidden, and the script swaps in the scheme and reveals the
+button once there is somewhere to send it. So with JavaScript off, or with the default
+left alone, the copy button and the selectable URL are the whole of it, which is all
+that was ever load-bearing.
+
 ## How it works
 
 Every request drives a real Chromium page load. One code path, and it survives markup
@@ -142,6 +171,10 @@ The one exception is Bluesky video, which is an HLS playlist — proxying it wou
 rewriting the manifest and every segment, so it is linked directly. Safari plays HLS
 natively; other browsers show a note.
 
+A page carrying a video asks iOS for the playback audio session. Without it a video
+playing inline is treated as ambience and the Ring/Silent switch mutes it, so the post
+plays perfectly and says nothing unless you go fullscreen.
+
 Resolved posts are cached in memory for an hour, so a reload or a back button doesn't
 drive the browser again.
 

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "antisocial",
-  "version": "1.2.1",
+  "version": "1.2.4",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "antisocial",
-      "version": "1.2.1",
+      "version": "1.2.4",
       "license": "UNLICENSED",
       "dependencies": {
         "@fastify/static": "10.1.3",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "antisocial",
-  "version": "1.2.1",
+  "version": "1.2.4",
   "private": true,
   "description": "Reads social posts back to you without the app.",
   "license": "UNLICENSED",

public/app.css

@@ -242,6 +242,30 @@ main { max-width: 680px; margin: 0 auto; }
 .index__table td { padding: 8px 8px 8px 0; border-top: 1px solid var(--line); vertical-align: middle; }
 .index__table code { overflow-wrap: anywhere; }
 
+.picker {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 8px 10px;
+  margin-top: 18px;
+  padding-top: 14px;
+  border-top: 1px solid var(--line);
+}
+/* The control ships hidden and is revealed by the script, and `display:
+   flex` above would otherwise beat the browser's own rule for [hidden]. */
+.picker[hidden] { display: none; }
+.picker__label { font-size: 13px; color: var(--ink-dim); }
+.picker__select {
+  font: inherit;
+  font-size: 14px;
+  padding: 7px 10px;
+  border-radius: 999px;
+  border: 1px solid var(--line);
+  background: var(--card);
+  color: var(--ink);
+}
+.picker__note { flex-basis: 100%; margin: 0; font-size: 12px; color: var(--ink-dim); }
+
 /* ---------- verification puzzle ---------- */
 
 .challenge__lede { margin: 14px; font-size: 14px; color: var(--ink-dim); }

public/app.js

@@ -1,7 +1,10 @@
 // Progressive enhancement only. Without this file the page still shows the
 // media in a swipeable rail and the original URL as selectable text.
 
+import { browsersFor, detectOs, openUrlFor } from './browsers.js';
+
 const VIEW_KEY = 'antisocial:view';
+const BROWSER_KEY = 'antisocial:browser';
 
 function setupCopy() {
   for (const button of document.querySelectorAll('.copy')) {
@@ -37,6 +40,62 @@ function setupCopy() {
   }
 }
 
+function storedBrowser() {
+  try {
+    return localStorage.getItem(BROWSER_KEY) ?? 'default';
+  } catch {
+    return 'default';
+  }
+}
+
+// The markup carries the plain address, which is the one thing the button
+// must not offer: followed in the browser the rewrite rules are installed
+// in, it redirects straight back to this page. So the link ships hidden and
+// is only revealed once a browser has been picked to hand it to. With no
+// choice made -- or none this system has a scheme for -- the copy button
+// and the URL below it are the whole of it.
+function applyBrowser(id) {
+  const os = detectOs();
+
+  for (const link of document.querySelectorAll('.original__open')) {
+    link.dataset.original ??= link.getAttribute('href');
+
+    const href = openUrlFor(link.dataset.original, id, os);
+    link.href = href;
+    link.hidden = href === link.dataset.original;
+  }
+}
+
+// Only on the index page, and only with this file running: the choice is
+// useless without the rewriting above, so the control ships hidden.
+function setupBrowserPicker() {
+  const select = document.querySelector('.picker__select');
+  if (!select) return;
+
+  for (const browser of browsersFor(detectOs())) {
+    const option = document.createElement('option');
+    option.value = browser.id;
+    option.textContent = browser.label;
+    select.append(option);
+  }
+
+  // A stored id with no scheme on this system would leave the control
+  // showing nothing at all, so fall back rather than render a blank.
+  const stored = storedBrowser();
+  select.value = [...select.options].some((option) => option.value === stored) ? stored : 'default';
+
+  select.addEventListener('change', () => {
+    try {
+      localStorage.setItem(BROWSER_KEY, select.value);
+    } catch {
+      // Private browsing. The choice just won't survive the page.
+    }
+    applyBrowser(select.value);
+  });
+
+  select.closest('.picker').hidden = false;
+}
+
 // One per rail: a post can carry several -- a thread of them, or a post and
 // the post it quotes -- and wiring only the first leaves the rest inert.
 function setupMedia(media) {
@@ -96,6 +155,19 @@ function setupMedia(media) {
   }
 }
 
+// On iOS a video playing inline gets the "ambient" audio session, which the
+// Ring/Silent switch mutes -- so the post plays perfectly and says nothing,
+// and the only way to hear it is to go fullscreen. Claiming "playback" says
+// what is true here: the sound is the point, not decoration. The session is
+// not activated until something actually plays, so declaring it up front
+// interrupts nothing; it is declared only on a page that has a video so an
+// ordinary text post never claims it at all.
+function setupAudioSession() {
+  if (!('audioSession' in navigator)) return;
+  if (!document.querySelector('video')) return;
+  navigator.audioSession.type = 'playback';
+}
+
 // Every comment is a <details open>, so folding one already works with this
 // file missing. All this adds is doing the whole page at once, which is why
 // the button ships hidden and is only revealed here.
@@ -127,7 +199,10 @@ function setupComments() {
 }
 
 setupCopy();
+applyBrowser(storedBrowser());
+setupBrowserPicker();
 for (const media of document.querySelectorAll('.media')) setupMedia(media);
+setupAudioSession();
 setupComments();
 
 // --- Verification puzzles -------------------------------------------------

public/browsers.js

@@ -0,0 +1,64 @@
+// The rewrite rules that send a shared link here catch the original link on
+// the way back out too, so in Safari "Open on <platform>" lands back on this
+// page. Handing the address to a different browser is the way out, and the
+// only way to do that from a web page is that browser's own URL scheme --
+// which every one of them spells differently. Some swap the scheme, some
+// prefix it, some take the whole address as a query parameter.
+
+/** http -> googlechrome://, https -> googlechromes:// */
+const chrome = (url) => url.replace(/^http(s?):/, 'googlechrome$1:');
+
+// Edge keeps the original scheme either way, but on macOS it stays in the
+// address and the scheme is prefixed, while on iOS it is folded into the
+// scheme itself.
+const edgeMacos = (url) => `microsoft-edge:${url}`;
+const edgeIos = (url) => url.replace(/^http(s?):/, 'microsoft-edge-http$1:');
+
+/** Firefox and Orion take the address as a parameter instead. */
+const openUrl = (scheme) => (url) => `${scheme}://open-url?url=${encodeURIComponent(url)}`;
+
+// `null` means the browser is there but ships no scheme to reach it on that
+// system, so there is nothing to offer beyond the plain link.
+export const BROWSERS = [
+  { id: 'default', label: 'Default browser', macos: null, ios: null },
+  { id: 'chrome', label: 'Chrome', macos: chrome, ios: chrome },
+  { id: 'edge', label: 'Edge', macos: edgeMacos, ios: edgeIos },
+  { id: 'firefox', label: 'Firefox', macos: null, ios: openUrl('firefox') },
+  { id: 'orion', label: 'Orion', macos: openUrl('orion'), ios: openUrl('orion') },
+];
+
+/**
+ * iPadOS calls itself MacIntel, so the platform string alone cannot tell the
+ * two apart; the touch points can. Everything else gets the desktop table --
+ * the only desktop this is ever opened on is a Mac.
+ *
+ * @param {{ platform?: string, maxTouchPoints?: number }} [nav]
+ */
+export function detectOs(nav = globalThis.navigator) {
+  const platform = nav?.platform ?? '';
+  if (/^iP(hone|ad|od)/.test(platform)) return 'ios';
+  if (platform === 'MacIntel' && (nav?.maxTouchPoints ?? 0) > 1) return 'ios';
+  return 'macos';
+}
+
+/** The browsers worth offering here: the default, plus the ones this system
+ *  actually has a scheme for. */
+export function browsersFor(os) {
+  return BROWSERS.filter((browser) => browser.id === 'default' || browser[os]);
+}
+
+function browserById(id) {
+  return BROWSERS.find((browser) => browser.id === id);
+}
+
+/**
+ * The address to open. A browser with no scheme on this system, an unknown
+ * id, or anything that is not an ordinary web link is handed back untouched:
+ * a dead custom scheme opens nothing at all, which is worse than the plain
+ * link opening in the wrong browser.
+ */
+export function openUrlFor(url, browserId, os) {
+  const rewrite = browserById(browserId)?.[os];
+  if (!rewrite || !/^https?:\/\//i.test(url)) return url;
+  return rewrite(url);
+}

src/platforms/reddit.ts

@@ -104,6 +104,10 @@ function fromRedditVideo(video: RedditVideo, poster: string | undefined): Media[
   const common = {
     ...sized(video.width, video.height),
     ...(video.duration ? { durationSec: video.duration } : {}),
+    // The still belongs to the video and not to the format it is served in.
+    // The HLS branch used to drop it, which is why a post with sound showed
+    // an empty box where every silent one showed a frame.
+    ...(poster ? { poster: { url: poster } } : {}),
   };
 
   if (video.has_audio !== false && video.hls_url) {
@@ -114,12 +118,7 @@ function fromRedditVideo(video: RedditVideo, poster: string | undefined): Media[
   if (url === video.hls_url) {
     return [{ kind: 'video', url, hls: true, direct: true, ...common }];
   }
-  return [{
+  return [{ kind: 'video', url, ...common }];
-    kind: 'video',
-    url,
-    ...(poster ? { poster: { url: poster } } : {}),
-    ...common,
-  }];
 }
 
 /** One entry of a gallery post. Reddit keeps the pictures somewhere other
@@ -192,14 +191,30 @@ function bodyOf(link: Link): string | undefined {
 /** The whole of `![...](...)`, with the target captured. */
 const INLINE_IMAGE = /!\[([^\]\n]*)\]\(([^)\s]+)\)/g;
 
+/**
+ * A Giphy token, which unlike the others says what it points at.
+ *
+ * Reddit writes a variant name after the id on some of them
+ * (`giphy|abc123|downsized`); only the id is kept, because Giphy does not
+ * serve every variant for every gif but always serves the full one.
+ */
+const GIPHY_TOKEN = /^giphy\|([A-Za-z0-9]+)(?:\|[a-z_]+)?$/;
+
 /**
  * Point a comment's inline images at something fetchable.
  *
  * Reddit writes them as `![gif](giphy|Ve7wX45)`, `![img](emote|t5_2th52|4358)`
- * or `![img](jo8gf0ca92zd1)` — a token rather than an address. In every case
+ * or `![img](jo8gf0ca92zd1)` — a token rather than an address. Usually the
- * the token is a key in that same comment's `media_metadata`, which is where
+ * token is a key in that same comment's `media_metadata`, which is where the
- * the real URL is, so one lookup covers all three and none of them needs
+ * real URL is, so one lookup covers all three and none of them needs naming
- * naming here.
+ * here.
+ *
+ * Usually, not always: Reddit ships plenty of comments carrying a Giphy token
+ * and no `media_metadata` at all, and with nothing to look the token up in
+ * those showed the token itself where the gif should have been. Giphy is the
+ * one kind that can be resolved without the lookup, the id in it being Giphy's
+ * own, so it falls back to Giphy's address for that id. The other two cannot:
+ * their ids mean nothing off Reddit.
  *
  * A target that is already an address is not a key, so it falls through
  * untouched.
@@ -208,15 +223,17 @@ export function resolveInlineImages(
   body: string,
   meta: Record<string, MediaMeta> | undefined,
 ): string {
-  if (!meta) return body;
-
   return body.replace(INLINE_IMAGE, (whole, alt: string, token: string) => {
-    const entry = meta[token];
+    const entry = meta?.[token];
-    if (!entry || entry.status !== 'valid') return whole;
+    if (entry?.status === 'valid') {
-    // An animated one has both; the GIF plays in an `<img>` on its own, which
+      // An animated one has both; the GIF plays in an `<img>` on its own,
-    // an MP4 does not.
+      // which an MP4 does not.
-    const url = entry.s?.gif ?? entry.s?.u;
+      const url = entry.s?.gif ?? entry.s?.u;
-    return url ? `![${alt}](${url})` : whole;
+      if (url) return `![${alt}](${url})`;
+    }
+
+    const giphy = GIPHY_TOKEN.exec(token)?.[1];
+    return giphy ? `![${alt}](https://i.giphy.com/media/${giphy}/giphy.gif)` : whole;
   });
 }
 

src/render/challenge.ts

@@ -28,7 +28,7 @@ export function renderChallenge(challenge: Challenge, box: Box | undefined): str
     <footer class="post__foot">
       <div class="original">
         <button type="button" class="copy" id="give-up">Give up and show me the link</button>
-        <a class="original__open" href="${challenge.originalUrl}" rel="noopener noreferrer nofollow" target="_blank">
+        <a class="original__open" href="${challenge.originalUrl}" rel="noopener noreferrer nofollow" target="_blank" hidden>
           Open on ${challenge.platformLabel}
         </a>
         <p class="original__url"><code>${challenge.originalUrl}</code></p>

src/render/index-page.ts

@@ -30,6 +30,14 @@ export function renderIndex(platforms: readonly PlatformSpec[]): string {
         )}
       </tbody>
     </table>
+    <section class="picker" hidden>
+      <label class="picker__label" for="open-in">Open original links in</label>
+      <select class="picker__select" id="open-in"></select>
+      <p class="picker__note">
+        The rewrite rules catch the original link too, so in Safari “Open on …” comes
+        straight back here. Another browser is a way out of that. Kept on this device.
+      </p>
+    </section>
   </article>`;
 
   return layout('antisocial', body);

src/render/layout.ts

@@ -43,14 +43,19 @@ export function badge(platform: string, label: string): Raw {
 }
 
 /** The copy control, plus the URL itself so it is always selectable even if
- *  the clipboard API is unavailable. */
+ *  the clipboard API is unavailable.
+ *
+ *  The open link ships hidden: followed in the browser the rewrite rules are
+ *  installed in, it redirects straight back here, so it is only worth showing
+ *  once a browser has been picked to hand it to. The script reveals it, and
+ *  the href in the markup is the plain address it starts from. */
 export function originalUrlBlock(originalUrl: string, platformLabel: string): Raw {
   return html`<div class="original">
     <button type="button" class="copy" data-url="${originalUrl}">
       <span class="copy__idle">Copy original link</span>
       <span class="copy__done" hidden>Copied</span>
     </button>
-    <a class="original__open" href="${originalUrl}" rel="noopener noreferrer nofollow" target="_blank">Open on ${platformLabel}</a>
+    <a class="original__open" href="${originalUrl}" rel="noopener noreferrer nofollow" target="_blank" hidden>Open on ${platformLabel}</a>
     <p class="original__url"><code>${originalUrl}</code></p>
   </div>`;
 }

src/render/post.ts

@@ -14,11 +14,29 @@ function aspect(item: Media): string {
   return item.width && item.height ? `aspect-ratio: ${item.width} / ${item.height};` : '';
 }
 
+/**
+ * A stand-in poster carrying nothing but the video's shape.
+ *
+ * The ratio above is not enough on its own before the video has any data: a
+ * `<video>` in that state has a natural size of 300x150, and WebKit sizes it
+ * from that rather than from the ratio, so a portrait video sat in a squat
+ * landscape box until you pressed play and it snapped to shape. A video's
+ * size before its data arrives is its poster's, which makes an empty SVG of
+ * the right shape enough to put the box right, and as a data URI it costs no
+ * request. Only for a video the platform gave no poster for, since a real one
+ * already says the same thing.
+ */
+function placeholderPoster(item: Media): string | undefined {
+  if (!item.width || !item.height) return undefined;
+  const svg = `<svg xmlns="http://www.w3.org/2000/svg" width="${item.width}" height="${item.height}"/>`;
+  return `data:image/svg+xml,${encodeURIComponent(svg)}`;
+}
+
 function renderItem(item: Media, index: number): Raw {
   const src = proxyUrlFor(item);
 
   if (item.kind === 'video') {
-    const poster = item.poster ? proxyUrlFor(item.poster) : undefined;
+    const poster = item.poster ? proxyUrlFor(item.poster) : placeholderPoster(item);
     return html`<figure class="item item--video" data-index="${index}">
       <video
         controls

test/browsers.test.ts

@@ -0,0 +1,47 @@
+import assert from 'node:assert/strict';
+import { test } from 'node:test';
+import { browsersFor, detectOs, openUrlFor } from '../public/browsers.js';
+
+const URL = 'https://www.instagram.com/p/ABC/?a=1&b=2';
+
+test('each browser gets the scheme it actually answers to', () => {
+  assert.equal(openUrlFor(URL, 'chrome', 'macos'), 'googlechromes://www.instagram.com/p/ABC/?a=1&b=2');
+  assert.equal(openUrlFor(URL, 'chrome', 'ios'), 'googlechromes://www.instagram.com/p/ABC/?a=1&b=2');
+  assert.equal(openUrlFor('http://example.com/a', 'chrome', 'ios'), 'googlechrome://example.com/a');
+
+  // Edge folds the scheme into its own on iOS and prefixes it on macOS.
+  assert.equal(openUrlFor(URL, 'edge', 'macos'), `microsoft-edge:${URL}`);
+  assert.equal(openUrlFor(URL, 'edge', 'ios'), 'microsoft-edge-https://www.instagram.com/p/ABC/?a=1&b=2');
+
+  // The parameter form has to be encoded, or the original query string ends
+  // up read as the opener's own.
+  assert.equal(openUrlFor(URL, 'orion', 'macos'),
+    `orion://open-url?url=${encodeURIComponent(URL)}`);
+  assert.equal(openUrlFor(URL, 'firefox', 'ios'),
+    `firefox://open-url?url=${encodeURIComponent(URL)}`);
+});
+
+test('a browser with no scheme on this system keeps the plain link', () => {
+  // Firefox on macOS has none, and a dead scheme opens nothing at all --
+  // worse than opening in the wrong browser.
+  assert.equal(openUrlFor(URL, 'firefox', 'macos'), URL);
+  assert.equal(openUrlFor(URL, 'default', 'ios'), URL);
+  assert.equal(openUrlFor(URL, 'nonesuch', 'ios'), URL);
+});
+
+test('only ordinary web links are rewritten', () => {
+  assert.equal(openUrlFor('mailto:[email protected]', 'chrome', 'ios'), 'mailto:[email protected]');
+  assert.equal(openUrlFor('/reddit/r/a/comments/b', 'chrome', 'ios'), '/reddit/r/a/comments/b');
+});
+
+test('only the browsers reachable on that system are offered', () => {
+  assert.deepEqual(browsersFor('macos').map((b) => b.id), ['default', 'chrome', 'edge', 'orion']);
+  assert.deepEqual(browsersFor('ios').map((b) => b.id), ['default', 'chrome', 'edge', 'firefox', 'orion']);
+});
+
+test('an iPad is told from a Mac by its touch points, not its platform string', () => {
+  assert.equal(detectOs({ platform: 'iPhone', maxTouchPoints: 5 }), 'ios');
+  assert.equal(detectOs({ platform: 'MacIntel', maxTouchPoints: 5 }), 'ios');
+  assert.equal(detectOs({ platform: 'MacIntel', maxTouchPoints: 0 }), 'macos');
+  assert.equal(detectOs({}), 'macos');
+});

test/reddit.test.ts

@@ -56,6 +56,7 @@ test('a video with sound is the HLS playlist, because the MP4 has no audio track
         duration: 42,
       },
     },
+    preview: { images: [{ source: { url: 'https://external-preview.redd.it/still.png', width: 1920, height: 1080 } }] },
   });
 
   assert.deepEqual(media, [
@@ -67,6 +68,9 @@ test('a video with sound is the HLS playlist, because the MP4 has no audio track
       width: 1920,
       height: 1080,
       durationSec: 42,
+      // The still is the video's, not the MP4's. Dropping it here left every
+      // post with sound showing an empty box where a silent one showed a frame.
+      poster: { url: 'https://external-preview.redd.it/still.png' },
     },
   ]);
 });
@@ -224,13 +228,63 @@ test('a target that is already an address is left alone', () => {
 });
 
 test('a token with no entry, or a broken one, is not invented', () => {
-  assert.equal(resolveInlineImages('![gif](giphy|missing)', GIPHY), '![gif](giphy|missing)');
+  // An upload id and an emote id mean nothing off Reddit, so with no entry to
+  // look them up in there is nothing to point them at.
+  assert.equal(resolveInlineImages('![img](missing)', GIPHY), '![img](missing)');
   assert.equal(
     resolveInlineImages('![img](gone)', { gone: { status: 'failed', e: 'Image' } }),
     '![img](gone)',
   );
 });
 
+test('a giphy token resolves even when the comment carried no metadata', () => {
+  // Reddit ships plenty of these with no `media_metadata` at all. The id in
+  // the token is Giphy's own, so it does not need Reddit to be readable.
+  assert.equal(
+    resolveInlineImages('![gif](giphy|zUW23b6FmzB5e)', undefined),
+    '![gif](https://i.giphy.com/media/zUW23b6FmzB5e/giphy.gif)',
+  );
+  assert.equal(
+    resolveInlineImages('![gif](giphy|missing)', GIPHY),
+    '![gif](https://i.giphy.com/media/missing/giphy.gif)',
+  );
+});
+
+test('the metadata still wins where there is any, being what Reddit will serve', () => {
+  assert.match(resolveInlineImages('![gif](giphy|Ve7wX45gaOFmw8eeEM)', GIPHY), /redd\.it/);
+});
+
+test('a variant name after the id is dropped, not all of them being served', () => {
+  assert.equal(
+    resolveInlineImages('![gif](giphy|zUW23b6FmzB5e|downsized)', undefined),
+    '![gif](https://i.giphy.com/media/zUW23b6FmzB5e/giphy.gif)',
+  );
+});
+
+test('only a giphy token is guessed at, and only a well-formed one', () => {
+  for (const token of ['emote|t5_2th52|4358', 'giphy|', 'giphy|../evil', 'giphy|a|b|c']) {
+    assert.equal(resolveInlineImages(`![x](${token})`, undefined), `![x](${token})`);
+  }
+});
+
+test('a real comment carrying a giphy token gets the gif', () => {
+  // Captured from the post itself: the comment has the token and no
+  // `media_metadata`, which is the shape that used to show the token instead.
+  const post = toPost(fixture('reddit/video.json'), URL_);
+  const all: string[] = [];
+  const walk = (list: typeof post.comments) => {
+    for (const comment of list ?? []) {
+      if (comment.text) all.push(comment.text);
+      walk(comment.replies);
+    }
+  };
+  walk(post.comments);
+
+  const gif = all.find((text) => text.includes('giphy'));
+  assert.ok(gif, 'the fixture should still carry a giphy comment');
+  assert.match(gif, /!\[gif\]\(https:\/\/i\.giphy\.com\/media\/QfzMP70zmNQiDf5sGP\/giphy\.gif\)/);
+});
+
 test('inline images survive the walk into the comment tree', () => {
   const { comments } = commentsFrom({
     data: {

test/render.test.ts

@@ -90,6 +90,27 @@ test('a video gets native controls and a source, not an iframe', () => {
   assert.ok(!page.includes('<iframe'));
 });
 
+test('a video with no poster still carries its shape, so the box is right before play', () => {
+  // WebKit sizes a video from its natural size, which without data or a
+  // poster is 300x150 — a portrait video sat in a landscape box until you
+  // pressed play. The poster is where the shape comes from until then.
+  const page = renderPost(withMedia([
+    { kind: 'video', url: 'https://video.example/p.m3u8', hls: true, direct: true, width: 720, height: 1280 },
+  ]));
+  assert.ok(page.includes('aspect-ratio: 720 / 1280;'));
+  assert.match(page, /poster="data:image\/svg\+xml,[^"]*width%3D%22720%22[^"]*height%3D%221280%22/);
+});
+
+test('a real poster is left in place, and an unmeasured video gets none', () => {
+  const withPoster = renderPost(withMedia([
+    { kind: 'video', url: 'https://cdn/v.mp4', width: 720, height: 1280, poster: { url: 'https://cdn/p.jpg' } },
+  ]));
+  assert.match(withPoster, /poster="\/m\//);
+  assert.ok(!withPoster.includes('data:image/svg'));
+
+  assert.ok(!renderPost(withMedia([{ kind: 'video', url: 'https://cdn/v.mp4' }])).includes('poster='));
+});
+
 test('the copy button carries the clean original URL, and so does the page text', () => {
   const page = renderPost(post());
   assert.ok(page.includes('data-url="https://www.instagram.com/p/ABC/"'));
@@ -105,8 +126,12 @@ test('a failure still hands the link back', () => {
     detail: 'TikTok showed a verification puzzle instead of the post.',
   });
   assert.ok(page.includes('data-url="https://www.tiktok.com/@a/video/1"'));
-  assert.ok(page.includes('Open on TikTok'));
+  assert.ok(page.includes('<code>https://www.tiktok.com/@a/video/1</code>'));
   assert.ok(page.includes('verification puzzle'));
+  // Following the original link in the browser the rewrite rules are
+  // installed in only comes back here, so it stays hidden until the script
+  // has a browser to hand it to.
+  assert.ok(/<a class="original__open"[^>]* hidden>Open on TikTok<\/a>/.test(page));
 });
 
 function redditPost(overrides: Partial<Post> = {}): Post {

tsconfig.json

@@ -17,6 +17,10 @@
     // Source imports carry the real `.ts` specifier so `node --experimental-
     // strip-types` can run the tree directly for dev, tests and the resolve
     // CLI. tsc rewrites them to `.js` on the way into dist.
+    // The client-side scheme table is plain JS, because the browser loads it
+    // as-is out of `public`. Its types are inferred so the test can check it.
+    "allowJs": true,
+
     "allowImportingTsExtensions": true,
     "rewriteRelativeImportExtensions": true,