macltok

# macltok

`macltok` is a compact Rust application backend built above `matrix-sdk` and

`matrix-sdk-ui`. It aims to provide the stateful behavior needed by a useful

Matrix client without depending on a GUI toolkit or inventing another protocol

SDK.

The crate currently provides

- typed commands, owned UI-safe events and bounded per-client transport

- Sliding Sync with normalized connection and room-list state

- independently retained live room timelines and backwards pagination

- text, emote, reply, edit, redaction, reaction, receipt and typing operations

- raw encrypted or unencrypted media acquisition with configurable byte limits

- encryption state, recovery-key import and SAS verification

- password login and session restoration with caller-owned encrypted SQLite stores

Matrix room, event, user, device and transaction identifiers remain strongly

typed. A toolkit timeline identity covers local echoes without pretending they

already have remote event IDs.

## Consuming the engine

Run `Engine::run` and drain its single `EventStream` independently of command

submission. `ClientHandle::send` returns an enqueue ID; match that ID against

`CommandSucceeded`, `CommandSucceededWithRoom`, or `CommandFailed` before

reporting completion. A successful message command only enters the SDK send

queue; the timeline item's send state reports subsequent network delivery.

Start a timeline from `TimelineReset`, then apply `TimelineChanged` diffs with

`TimelineDiff::try_apply`. If a diff does not match the current snapshot, stop

applying diffs for that timeline and send `TimelineCommand::Resync`. Resume only

after its fresh `TimelineReset`; the reset precedes the command completion.

With `sqlite`, persist the initial `Session::record()` separately from its

encrypted SQLite store. On `SessionTokensChanged`, obtain a new record from

`ClientHandle::session_record()` and replace the saved record atomically in

protected storage. Restore with the same store path and passphrase. Delete the

saved credentials after `LoggedOut` or `SessionAccessRejected`, but keep them

after `Stopped` so a restart can restore the session. The headless example is

login-only; it does not persist sessions across runs.

## Dependency policy

UI frameworks, image decoders, application-directory discovery and logging

subscribers do not belong in this crate. SQLite remains optional through the

`sqlite` and `bundled-sqlite` features. Media decoding belongs to the consumer.

## Verification

```sh

nix develop --command cargo fmt -- --check

nix develop --command cargo test --all-targets

nix develop --command cargo test --all-targets --features sqlite

nix develop --command cargo clippy --all-targets -- -D warnings

nix develop --command cargo clippy --all-targets --features sqlite -- -D warnings

nix flake check

```