halkyon/apps/learn/README.md

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# Halkyon Learn
Halkyon Learn is for creating, sharing and collaborating on study material. It schedules
flashcards with [FSRS](https://github.com/open-spaced-repetition) to strengthen
retention, and organises study material together with the external references it draws
on. It is offline-first: everything works on the device, without a connection. And the
whole stack is transparent: the app, the server and everything needed to host an
instance are published, so anyone can see how an instance works and run their own.
- **Offline first.** Each device keeps its own database and syncs in the background
(`serverpod_offline_sync`). Edits made on two devices while offline are never lost:
card content is stored as append-only revisions, and a side changed differently on two
devices is shown as a conflict until the person picks a version
([ADR 0001](../../docs/adr/0001-offline-sync.md), [ADR 0003](../../docs/adr/0003-card-revisions.md)).
- **Every account has a way in**: SimpleLogin, whose ID alone the instance keeps, or an
email address with a password and an authenticator, the password never leaving the
device ([ADR 0020](../../docs/adr/0020-sign-in-with-simplelogin.md),
feat(base,app)!: GitHub signs nobody in any more (ADR 0020, D36) Every account signs in with SimpleLogin or a password now, so GitHub goes from the module, the shared app package, Learn and Todo, ahead of ADR 0017's GITHUB_SIGN_IN_ENDS. - halkyon_base: no `gitHubSignIn` endpoint, GitHub identity provider or GitHub refusals; no `githubClientId`/`githubClientSecret`, no `GITHUB_SIGN_IN_ENDS` and no `forgetGitHubAccounts`; the register loses `account-with-github`. `SignInWays.gitHub`, the basics' `gitHubClientId` and `gitHubSignInEnds`, and `PasswordRefusal`'s `signInAgain` and `noAddress` go. A first password takes a code mailed to the person's own address; an account without one sets none (`wrongCredentials`). - Learn's server: `instance.info()` without `gitHubClientId`, the pruning without GitHub, and `minimumAppBuild` 24, as builds up to 23 (v0.20.0) require `SignInWays.gitHub`: the server deploys with the release of build 24. - halkyon_app: no GitHub button or problems on the start screen, no password offered after a GitHub sign-in, and `ServerpodAuthGateway` without the browser half only GitHub used (`(client, base:)`). The account section offers a first password only to an account with an address. `LoopbackWebAuth` and the apps' schemes stay, SimpleLogin's ways back. - Learn's Profile lists no GitHub; the texts go (English, German). - Serverpod's `serverpod_auth_idp_github_account` stays, as its migrations make it; a row goes with its account, and ADR 0020's D36 gives operators the SQL to delete those left. - deploy/: compose.yaml and .env.example without GitHub. The READMEs, AGENTS.md files and ADR 0017 amended. BREAKING CHANGE: builds up to 23 can't read the instance's answers about an account's ways in; minimumAppBuild is 24. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
2026-10-25 12:52:52 +01:00
[ADR 0017](../../docs/adr/0017-password-totp-and-keys.md)).
- **Private studysets are end-to-end encrypted.** A private studyset's content is sealed
on the device with the account's keys; what isn't private, and what is published, the
operator of the instance can read, as on Mastodon
([ADR 0019](../../docs/adr/0019-private-studysets.md),
[ADR 0002](../../docs/adr/0002-no-end-to-end-encryption.md)).
Targets: Linux, Windows, macOS, Android and iOS. There is no web build.
## Packages
Learn lives in `apps/learn/` of the Halkyon repository, one workspace with Halkyon's
other apps and the packages they share ([the repository's README](../../README.md)).
| Package | What it is | Licence |
|---|---|---|
| `halkyon_learn_server` | The [Serverpod](https://serverpod.dev) server: endpoints, models, migrations | SSPL-1.0 |
| `halkyon_learn_client` | The client, generated from the server's models | AGPL-3.0-or-later |
| `halkyon_learn_flutter` | The app (`app.halkyon.learn`) | AGPL-3.0-or-later |
| `halkyon_learn_curator` | Turns dictionary sources into the files the server loads | AGPL-3.0-or-later |
It builds on the shared packages in `packages/`: `halkyon_base` (sign-in, accounts, the
instance's basics; a Serverpod module), `halkyon_app` (instances, sign-in, sync),
`halkyon_editor` (rich text) and `halkyon_ui` (the look).
## Setting up
- **Flutter v3.47.8**, the version CI uses (`FLUTTER_VERSION` in
`.forgejo/workflows/ci.yaml`). Set up each platform you build for with Flutter's own
guides: [Linux](https://docs.flutter.dev/platform-integration/linux/setup),
[Windows](https://docs.flutter.dev/platform-integration/windows/setup),
[Android](https://docs.flutter.dev/platform-integration/android/setup),
[macOS](https://docs.flutter.dev/platform-integration/macos/setup),
[iOS](https://docs.flutter.dev/platform-integration/ios/setup).
- **The Serverpod CLI v4.0.4**: `dart install serverpod_cli@4.0.4`. Pass `--no-analytics`
to every call; otherwise it reports the commands run to Serverpod.
- **Linux**, on top of Flutter's packages, the libraries of four plugins: WebKitGTK
(pulled in by the sign-in package), libsecret (keeps the session), GStreamer (plays
sounds) and libmpv (plays videos from Jellyfin; the app doesn't start without it).
On Debian or Ubuntu, Flutter's and these together:
```sh
sudo apt-get install clang cmake ninja-build pkg-config libgtk-3-dev libstdc++-12-dev \
libwebkit2gtk-4.1-dev libsecret-1-dev libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev \
libmpv-dev
```
- **Windows** needs Developer Mode (Settings › System › For developers): building makes
symbolic links, as Flutter links each plugin's native code into the build and the PDF
engine's build does too, and Windows lets ordinary users make them only in Developer
Mode.
- **No Docker** for development: `serverpod start` and the server's tests run an embedded
PostgreSQL. Docker Compose is only for running an instance (below).
- **For Learn's scripts in `apps/learn/tool/`**, run from `apps/learn`: Python 3; for
the apps' icons (the repository's `tool/app_icons.py`, run from the root) also Pillow,
PyGObject with librsvg and pycairo (`python3-pil`, `python3-gi`, `gir1.2-rsvg-2.0`,
`python3-cairo`); for releases what [Releases](#releases) lists.
The rich-text editor comes from our fork of AppFlowy Editor
([halkyon-days/appflowy-editor](https://code.halkyon.app/halkyon-days/appflowy-editor)),
which `flutter pub get` fetches by itself.
## Running it locally
The server's secrets live in `apps/learn/halkyon_learn_server/config/passwords.yaml`,
which is never committed. In a fresh clone, create it with a `development` and a `test`
section, each holding `database`, `serverSideSessionKeyHashPepper` and `serviceSecret`
feat(base,app)!: GitHub signs nobody in any more (ADR 0020, D36) Every account signs in with SimpleLogin or a password now, so GitHub goes from the module, the shared app package, Learn and Todo, ahead of ADR 0017's GITHUB_SIGN_IN_ENDS. - halkyon_base: no `gitHubSignIn` endpoint, GitHub identity provider or GitHub refusals; no `githubClientId`/`githubClientSecret`, no `GITHUB_SIGN_IN_ENDS` and no `forgetGitHubAccounts`; the register loses `account-with-github`. `SignInWays.gitHub`, the basics' `gitHubClientId` and `gitHubSignInEnds`, and `PasswordRefusal`'s `signInAgain` and `noAddress` go. A first password takes a code mailed to the person's own address; an account without one sets none (`wrongCredentials`). - Learn's server: `instance.info()` without `gitHubClientId`, the pruning without GitHub, and `minimumAppBuild` 24, as builds up to 23 (v0.20.0) require `SignInWays.gitHub`: the server deploys with the release of build 24. - halkyon_app: no GitHub button or problems on the start screen, no password offered after a GitHub sign-in, and `ServerpodAuthGateway` without the browser half only GitHub used (`(client, base:)`). The account section offers a first password only to an account with an address. `LoopbackWebAuth` and the apps' schemes stay, SimpleLogin's ways back. - Learn's Profile lists no GitHub; the texts go (English, German). - Serverpod's `serverpod_auth_idp_github_account` stays, as its migrations make it; a row goes with its account, and ADR 0020's D36 gives operators the SQL to delete those left. - deploy/: compose.yaml and .env.example without GitHub. The READMEs, AGENTS.md files and ADR 0017 amended. BREAKING CHANGE: builds up to 23 can't read the instance's answers about an account's ways in; minimumAppBuild is 24. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
2026-10-25 12:52:52 +01:00
(for example from `openssl rand -base64 32`).
Then start the server, its embedded database and the app:
```sh
cd apps/learn/halkyon_learn_server
serverpod --no-analytics start
```
`serverpod start` applies pending migrations and reloads on changes. The app talks to the
server named by `--dart-define=SERVER_URL=…`, or else to the one in
`apps/learn/halkyon_learn_flutter/assets/config.json` (`http://localhost:8080`). Without
`--no-analytics`, the Serverpod CLI reports usage to Serverpod.
## Tests
From the repository's root,
```sh
dart run tool/check.dart
```
runs the format check, the analyzer with the strict lints of `leancode_lint` and every
package's tests, Learn's server's (against an embedded PostgreSQL, no Docker needed), its
curator's and its app's among them; `dart run melos run test:flutter
--scope=halkyon_learn_flutter` runs the app's alone. To run the checks before every push:
`ln -s ../../tool/pre-push .git/hooks/pre-push`. CI runs them on every push too
(`.forgejo/workflows/ci.yaml`).
The sync tests need a running server (`serverpod start`); run them in
`apps/learn/halkyon_learn_flutter` with `flutter test -t requires-server`.
## Running an instance
`deploy/`, at the repository's root, holds a Docker Compose setup: Caddy (HTTPS), the
server and PostgreSQL. Copy `deploy/.env.example` to `deploy/.env` and fill it in; it
explains every value. The licences require offering the source of what the instance runs
feat(assistant)!: no hand-off and no connector; the field searches the web (ADR 0022) The developer decided on 23 Oct to drop the hand-off to an AI assistant outside the app, and Claude's connector with it, in v0.19.0, the app and the server together: build 22 raises minimumAppBuild anyway, so no app calling the connector's endpoints uses the instance after it. An instance is to have one way to an assistant, its operator's (ADR 0021, proposed). The app: the field at the foot of Home, and the button in the Library, on a studyset and while studying, search the web alone, through the engine chosen in Settings or Android's own search, with the parts of a card the person picks; a studyset's name and description are never offered. Gone: the assistants a question opened in (AiAssistant, AssistantHandOff), the switch between them and the web, Settings' choice of assistant, Connect Claude with its route, cubit, repository and gateway, and their texts. A settings file from before keeps the old keys until the next change of a setting writes it anew; nothing reads them. The server: lib/src/assistant/ (MCP, its OAuth, the five tools, connect codes and tokens), AssistantEndpoint, the daily forgetting of the connector's secrets (its scheduled call cancelled at start), its lines in the deletion hook, instance.info().assistantConnectorUrl (nullable, so an older app reads it as none), and Caddy's forwarding of /mcp, /oauth/* and /.well-known/oauth-*. The migration drops the connector's five tables, children first: DROP TABLE "assistant_token" CASCADE; -- tokens of a connection DROP TABLE "assistant_grant" CASCADE; -- OAuth codes of a connection DROP TABLE "assistant_connection" CASCADE; -- a person's connected client DROP TABLE "assistant_connect_code" CASCADE; DROP TABLE "assistant_client" CASCADE; -- OAuth clients registered No other table references them, so CASCADE drops only their own foreign keys. For the minute between the maintenance run and the switch, the old server answers the connector with errors and fails to delete an account (its hook still deletes from these tables); ADR 0022 says so. BREAKING CHANGE: a connected Claude gets no answer from the deploy on, and the app no longer opens a question in an AI assistant. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>
2026-10-23 15:33:53 +02:00
to the people who use it.
learn.halkyon.eu itself deploys from `main` once CI is green: `deploy/redeploy.sh`, run by
the CI runner described in `deploy/runner/`, deploys only commits signed by a key in
`deploy/allowed-signers`. It backs up its database every hour, off-site and encrypted;
[`deploy/backups.md`](../../deploy/backups.md) says how to set that up and how to restore.
## Releases
Releases are published on [code.halkyon.app](https://code.halkyon.app/halkyon-days/halkyon/releases),
with the APK and the snap, and the APK also in the project's F-Droid repository
(`https://halkyon.app/fdroid/repo?fingerprint=E8082788756F6B7E682AA22FCEAD24B53E2A8B0912AD66D65E8C2D4F07BB94B0`,
added in the F-Droid app as a repository). The Snap Store (`halkyon-learn`) follows.
Their builds offer learn.halkyon.eu, the project's instance, at first start; people
may choose another there, and keep accounts on several.
- **Checking a download:** `SHA256SUMS` lists the checksum of every file, signed with the
maintainer's GPG key (`SHA256SUMS.asc`). The APK is signed with the app's key, whose
certificate has the SHA-256
`27:E2:43:FC:BD:C8:26:FF:98:AB:7D:BB:10:43:6C:98:C3:BE:A2:4B:2A:01:5E:94:E4:CF:C7:D1:FC:2A:00:6C`
(`apksigner verify --print-certs` shows it).
- **Versions** follow [semantic versioning](https://semver.org): `version` in
`apps/learn/halkyon_learn_flutter/pubspec.yaml`, `<major>.<minor>.<patch>+<build>`.
Since the last release, a commit typed `feat` raises the minor number, `fix` or `perf` the patch
number, and a breaking one (`feat!:` or a `BREAKING CHANGE:` line) the major number from
1.0 on, the minor one before; other commits release nothing by themselves. Every
release raises the build number: Android only installs a higher one over an older, and
the server tells apps below the build it supports to update.
- **Making one** is for maintainers, on their own machine and never in CI, from the
repository's root: `dart run tool/release.dart learn`, or with `minor` (or `major`,
`patch`) after `learn` to choose; `--dry-run` shows what it would do and changes
nothing. It is the apps' shared release tool ([ADR 0015](../../docs/adr/0015-one-repository.md)),
configured in `apps/learn/release.dart`. It needs `main` clean, pushed and green in CI, the app's key, the
F-Droid repository's key and a Forgejo token; its header says more. Tags are
`learn-vX.Y.Z`, and only commits touching Learn count for its version. It shows the version and its commits and asks
first, then writes the version into the pubspec in a signed release commit with a
signed tag, builds the APK and the snap (`snap/snapcraft.yaml`, built in LXD; its icon
comes from the repository's `tool/app_icons.py`), checks both, signs the checksums, pushes, and
publishes on code.halkyon.app, in the F-Droid repository and in the Snap Store's edge
channel (`snapcraft login` first). Besides Flutter and the Android SDK, it uses snapcraft with
LXD, a JDK (keytool), GnuPG, curl, jq, unzip, squashfs-tools, rsync and fdroidserver.
Release builds made without the app's key are signed with the debug key and can't
update a released app.
- **The F-Droid repository** is kept by `tool/fdroid_repo.sh` (fdroidserver v2.4.5,
e.g. `pipx install fdroidserver==2.4.5`); its settings and the app's listing are in
`tool/release/fdroid/`.
## More
- [`AGENTS.md`](AGENTS.md): how Learn's code is organised and the rules it follows; the
[repository's](../../AGENTS.md) for what holds for every app.
- [`docs/adr/`](../../docs/adr/): the architecture decisions and their reasons.
- [`CONTRIBUTING.md`](../../CONTRIBUTING.md): licences of contributions and the sign-off.
- [`LICENSE.md`](../../LICENSE.md): which licence covers what.