Flack

Flack copies new Slack messages into the format Android Auto reads aloud: DMs, group DMs, public and private channels, and thread replies. When a notification provides one safe reply action, you can dictate and confirm a reply. Flack hands your words to that original Slack action, once. With optional Slack sign-in, notifications without a usable reply action can receive a top-level API reply when their conversation and workspace identifiers pass the checks in the sign-in design.

Status: experimental support for these notification types, with synthetic routing tests. Real Slack and car behavior, including readout without a reply action, still need device tests. See the device test record.

Download

On your Android phone, open flack.apk. This link always gets the newest release. Then follow the install steps, or use the download page.

Flack is not on Google Play. You install it yourself, and you turn on Android Auto's "Unknown sources" developer setting so it shows Flack's messages.

How it works

1. Flack reads notifications from the official Slack app only. It ignores every other app before reading anything.
2. While Android Auto is connected, it posts a readable copy of each eligible text notification. Group summaries are suppressed to avoid duplicate announcements.
3. When you confirm a reply in the car, Flack checks a one-time token and passes your text to Slack's reply action. Slack sends the message.

If Flack cannot tell where a reply would go, it keeps a read-only phone copy. Android Auto requires both reply and mark-as-read actions, so it may hide these read-only copies. For every conversation type, Flack uses the phone notification's single free-form action with the REPLY semantic action, after checking that it does not open an app. No label selects a route. Ambiguous semantic reply choices, unknown conversation shape, missing group context, or a shared source action disable replying. Flack never chooses a destination from a sender or channel name. The capability table records the rules and evidence limits.

Flack follows your Slack mobile notification settings. Whatever Slack notifies you about on your phone can reach the car. For channel messages, Slack must be set to notify you about mentions or All new messages.

The status screen's Hide Flack copies on the phone switch is on by default. It puts copies in a silent channel with minimum importance; Android cannot remove them from the phone shade completely. Android Auto may also hide these quiet copies. If the car stays empty, turn the switch off and receive a new Slack message. Switching clears current copies and their reply tokens. The alerting mode can produce a duplicate phone alert.

Privacy

• Slack sign-in is optional. Without it, Flack makes no network requests, and the Slack app does the sending.
• If you sign in, Flack talks only to Slack, over HTTPS. Its Slack token is encrypted with an Android Keystore key and is never logged or shown. Sign out deletes it and asks Slack to end the sign-in. See Slack sign-in.
• Message text stays in memory and is never saved, backed up or logged.
• Flack asks for two permissions: posting notifications, and internet for Slack sign-in. CI fails any build that asks for more.

The full privacy page covers what Flack reads, keeps and sends.

Supported phones

The intended test phones are a Samsung Galaxy S24 Ultra and a Samsung Galaxy S21. Neither has been tested yet; results and exact versions go in the device test record. Flack needs Android 12 or later.

Documentation

• Install and test steps
• Specification and project rules
• Test plan and device test record
• Roadmap
• Brand guide, design rules and writing rules
• Releasing and changelog
• Contributing and security policy

Build

./gradlew testDebugUnitTest lintDebug assembleDebug

Needs JDK 21 and the Android SDK. See CONTRIBUTING.md for the full checks.

License

Apache-2.0 for original work. See LICENSE and NOTICE. The Manrope font in site/fonts/ is under the SIL Open Font License.

Flack is an independent project. It is not made by, affiliated with or endorsed by Slack, Google or Samsung.