/dev/null on TV

A big-screen client for dev-null.sh, the social network for developers (source), packaged as a Samsung Tizen TV app. It reads the site's public, read-only API, so it needs no login: the log shows commits from the developers you add on the TV, drawn the way the site draws them, as a git log --graph.

Showcase

Captured in desktop Chrome at 1920×1080 against the live API, with the TV's four default people.

In motion

Ambient: Scroll	Menu and Settings	Ambient: Terminal

Screens

Log. Everyone on this TV on one graph rail; code is highlighted like on the site.	Commit. The full commit, link card and images; the QR code opens it on your phone.
Profile. Lane ring, counts, activity graph, Commits and Replies.	Image viewer. A commit's images, full screen.
Menu. ◀ from any screen.	People. The TV's own follow list.
Settings. Pick an ambient style; ▶ previews the focused one.	About. What dev-null.sh is, and the TV's engine.
Ambient: Scroll. One commit per screen on a continuous rail.	Ambient: Still. Commits cross-fade beside a fixed node.
Ambient: Timeline. A node per commit along the bottom.	Ambient: Terminal. git show, then the commit types itself out.
Boot. Shown until the log has loaded.

Why a separate app

The site itself can't run on these TVs. Their web engine is an older Chromium that can't handle the site's Tailwind 4 stylesheet, so it loads as a giant unstyled logo. This app is plain HTML, CSS and ES2017 with the fonts bundled, and talks only to the public API.

Screens

Screen	What it shows
Log	Commits from everyone on this TV, newest first on one graph rail, with day markers, HEAD@{last visit}, and a "↑ N new commits" pill when the minute poll finds more. The aside previews the focused author.
Commit	The full commit with its link card and images, the parent when it is a reply, and a QR code that opens it on your phone for replying or starring.
Profile	Avatar with lane ring, mirrored GitHub details, counts, the public activity graph, and Commits / Replies tabs.
Image viewer	Full-screen images, stepping through a commit's images.
People	The TV's own follow list: add a GitHub username (checked against the API first) or remove one. Stored on the TV.
Ambient	After two idle minutes, or on PLAY, the latest commits one at a time, read from across the room. The text takes the largest size (104 to 40 px) at which the whole commit fits; an image, or a short commit's link picture, sits beside it. Each commit shows for 12 s (AMBIENT_MS) in one of four styles picked in Settings: Scroll (the log scrolls up, one node per screen on a continuous rail), Still (commits cross-fade beside a fixed node), Timeline (a row of nodes along the bottom) or Terminal (git show, then the commit types itself out). The key hint fades after 5 s (AMBIENT_HINT_MS). CH ▲▼ browses; any other key returns.
Settings	The ambient style, stored on the TV, each shown as a small animated sketch. OK picks a style; PLAY previews the focused one without picking it.
About	What dev-null.sh is, the refresh rate and the TV's web engine version.

Remote keys

Key	Does
▲ ▼	Move between commits (on the commit page: scroll)
◀ ▶	◀ opens the menu; on a commit, move between author, link and images; on a profile's tabs, switch tabs
OK	Open the focused commit, author, link (in the TV's browser) or image
CH ▲ ▼	Jump 5 commits; on the commit page, previous / next commit; in ambient mode, newer / older commit
PLAY	Ambient mode (on Settings: preview the focused style)
BACK	Back; on the log, exit

Install on your TV

Samsung TVs only install apps signed with a Samsung certificate made for that TV, and only in Developer Mode. Setting that up takes about 15 minutes once. These steps are for macOS; Linux is the same apart from the installer file.

You need: just, Node 18+, and the TV and your computer on the same network.

1. Turn on Developer Mode on the TV. Open Apps and enter 1 2 3 4 5 (with an on-screen number pad if your remote has no number keys). Switch Developer Mode On, enter your computer's IP address as Host PC IP, then restart the TV by holding the power button until the logo appears.

2. Install the Tizen Studio command-line tools (no IDE needed):

curl -O https://download.tizen.org/sdk/Installer/tizen-studio_6.1/web-cli_Tizen_Studio_6.1_macos-64.bin
chmod +x web-cli_Tizen_Studio_6.1_macos-64.bin
./web-cli_Tizen_Studio_6.1_macos-64.bin --accept-license ~/tizen-studio
~/tizen-studio/package-manager/package-manager-cli.bin install --accept-license cert-add-on

If the package manager says the JDK is missing, an earlier failed run left an empty ~/.package-manager/jdk folder behind: remove it with rmdir ~/.package-manager/jdk and run the command again.

3. Copy out Samsung's TV CA certificates. They ship inside the certificate extension:

mkdir -p ~/tizen-studio-data/samsung-ca
unzip -j ~/tizen-studio/tools/certificate-manager/Certificate-manager.app/Contents/Eclipse/plugins/org.tizen.common.cert_*.jar \
  res/ca/vd_tizen_dev_author_ca.cer res/ca/vd_tizen_dev_public2.crt -d ~/tizen-studio-data/samsung-ca

4. Connect to the TV and read its device ID (DUID). The sdb server dies when started in the background on some setups, so run it in its own terminal:

just sdb-server                 # terminal 1, leave it running
TV=192.168.1.20:26101 just connect
~/tizen-studio/tools/sdb shell 0 getduid

5. Get your Samsung certificate. samsung-tv-cert signs you in to a free Samsung account in the browser and writes an author and a distributor certificate for your TV:

npx samsung-tv-cert@1.0.0 --duid <YOUR-DUID> --profile devnull-tv

6. Register the certificates as a signing profile:

C=~/tizen-studio-data/SamsungCertificate/devnull-tv
CA=~/tizen-studio-data/samsung-ca
PW="$(cat ~/.samsung-tv-cert-password)"
~/tizen-studio/tools/ide/bin/tizen security-profiles add -n devnull-tv -A \
  -a "$C/author.p12" -p "$PW" -d "$C/distributor.p12" -dp "$PW" \
  -dc "$CA/vd_tizen_dev_public2.crt" -c "$CA/vd_tizen_dev_author_ca.cer"
~/tizen-studio/tools/ide/bin/tizen cli-config "profiles.path=$HOME/tizen-studio-data/profile/profiles.xml"

7. Build, install and launch:

TV=192.168.1.20:26101 just deploy

It shows up in the TV's app list as dev-null.sh. just deploy re-signs and reinstalls after any change; TIZEN_PROFILE picks a different signing profile.

Development

There is no build step: app/ is the whole app, and just package signs it into build/dev-null.sh.wgt.

just preview    # open app/index.html in desktop Chrome at 1920×1080 against the live API
just deploy     # sign, install and launch on the TV
just run        # launch the installed app

Desktop Chrome is fine for layout work, but it is far newer than the TV's engine. Keep to what the TV supports:

• JavaScript: ES2017, plus the engine's RegExp lookbehind and \p{…} escapes. No ?., ??, private class fields or top-level await.
• CSS: no gap on flex containers (grid gap is fine), inset, aspect-ratio, :has(), oklch() or cascade layers.
• Text: every commit body, name and bio goes through textContent, never innerHTML.

Launch screen. The page's first paint is its own boot screen (#boot in app/index.html): the artwork in app/splash/splash.png with a pulsing node, until the log has loaded (with an 8 s fallback). On this 2021 TV, Samsung's own "dev-null.sh Loading…" screen shows briefly before that and can't be replaced. app/config.xml also declares Samsung's video splash (tizen:video_splash_screen, ready_when="first-paint") for TVs that support it: a two-second fade-in video, handing over to the identical boot screen. Its video attribute is required: without it the TV rejects the package with a parsing error. To change the artwork, edit design/splash.html, render it at 1920×1080 to app/splash/splash.png (under 200 kB), and rebuild the video:

ffmpeg -loop 1 -i app/splash/splash.png -t 2 -r 30 -vf "fade=t=in:st=0:d=1.2,format=yuv420p" \
  -c:v libx264 -crf 26 -movflags +faststart -an app/splash/intro.mp4

design/screens.html is the design document the app was built from: every screen at 1920×1080 with real commits, following dev-null.sh's design system. design/ambient-variants.html is the study the ambient styles came from: five transitions running side by side on sample commits from fictional people.

How it works

• Data: GET /api/v1/users/{u}, /api/v1/users/{u}/commits (and ?replies=1), /api/v1/commits/{id}, and the public activity graph at /@{u}/graph.svg?theme=dark. The API has no global feed, which is why the log is built from the people you add.
• Lane colors. The API doesn't return the lane someone picked in their dev-null.sh settings, but their activity graph is drawn in it, so the app reads each person's lane from /@{u}/graph.svg?theme=dark once per session and stores it on the TV. Anyone else (authors of parent commits) gets the site's automatic lane, a hash of the user id (User::automaticLane).
• Code. Fenced blocks and inline code follow the site's rules (CodeSpans.php): mentions, links and the wordmark never apply inside code. The site highlights code on its server with tempest/highlight, and the API returns only the raw text, so app/js/highlight.js is a JavaScript port of tempest 2.28.1 for PHP, shell, JS, TS and JSON with the site's token colors. It was checked token by token against tempest's own output.
• The /dev/null wordmark. Like the site, a standalone /dev/null in a commit renders as the wordmark with the outlined orange slash; longer paths, words and inline code stay plain.
• Links open in the TV's own browser through tizen.application.launchAppControl.
• Keys like PLAY and the channel buttons are registered with tizen.tvinputdevice.

Compatibility

Tested on a Samsung QE55Q65AAUXXC (2021, Tizen 6.0); other Tizen TVs are untested. Not yet confirmed on that TV: opening links in the TV's browser and typing a username on the People screen. The About screen shows the TV's web engine version, which helps when reporting problems.

If the app installs but shows only a black screen, the package's config.xml is the likely cause: during development, an app name containing / and a tizen:allow-navigation element both coincided with a black screen on this TV. Keep config.xml close to Samsung's template, as app/config.xml is.

Credits

• dev-null.sh by Nuno Maduro and contributors: the name, logo, design system and API. This app is unofficial.
• Geist and Geist Mono by Vercel, under the SIL Open Font License (app/fonts/OFL.txt).
• qrcodejs by Shim Sangmin, MIT license.

The app's own code is MIT. The dev-null.sh logo in app/icon.png belongs to dev-null.sh, whose repository has no license; it is used here as the TV app icon.