FormerLab/fortransky: We built a terminal-only Bluesky / AT Protocol client written in Fortran, with a Rust native firehose decoder for the relay-raw stream path. Yes, that Fortran. · GitHub

Yes, that Fortran.

A terminal-only Bluesky / AT Protocol client written in Fortran, with a Rust
native firehose decoder for the relay-raw stream path.

Fortran TUI  (src/)
  └─ C libcurl bridge  (cshim/)
  └─ Fortran iso_c_binding module  (src/atproto/firehose_bridge.f90)
       └─ Rust staticlib  (bridge/firehose-bridge/)
            envelope → CAR → DAG-CBOR → NormalizedEvent → JSONL
            + firehose_bridge_cli binary  (used by relay_raw_tail.py)

Session state is saved in ~/.fortransky/session.json. Use an app password,
not your main Bluesky password.

sudo apt install -y gfortran cmake pkg-config libcurl4-openssl-dev

Requires rustc >= 1.70. Install via rustup if not present:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

The relay_raw_tail.py helper is launched as a subprocess by the TUI. It must
be able to import cbor2 and websockets using whichever python3 is on
PATH at the time Fortransky runs — not just in an active venv.

Option A — system-wide (simplest):

sudo pip install cbor2 websockets --break-system-packages

Option B — venv, then symlink or alias:

python3 -m venv .venv
source .venv/bin/activate
pip install cbor2 websockets

Then either run Fortransky with the venv active, or set:

export FORTRANSKY_RELAY_PYTHON=$PWD/.venv/bin/python3

(support for this env var is planned)

This builds the Rust bridge first (cargo build --release), then runs CMake.
The Rust step is skipped on subsequent builds if nothing changed.

Use an app password created for
Fortransky specifically. At the home prompt:

l
Identifier: yourhandle.bsky.social
Password/app password: 

Session is saved to ~/.fortransky/session.json and restored on next launch.
To log out: x

jetstream — connects to Bluesky’s Jetstream WebSocket service. Lower
bandwidth, JSON native, easiest to work with.

relay-raw — connects to the raw AT Protocol relay
(com.atproto.sync.subscribeRepos). Frames are binary CBOR over WebSocket.
The native Rust decoder (firehose_bridge_cli) handles envelope → CAR →
DAG-CBOR → normalized JSON. Python cbor2 fallback remains for fixture mode.

1. FORTRANSKY_FIREHOSE_DECODER environment variable
2. bridge/firehose-bridge/target/release/firehose_bridge_cli
3. bridge/firehose-bridge/target/debug/firehose_bridge_cli
4. firehose_bridge_cli on PATH

By default relay-raw uses a bundled synthetic fixture. To use the live relay:

FORTRANSKY_RELAY_FIXTURE=0 ./build/fortransky

Quick offline demo:

printf 'b\nm\nj\nb\nq\n' | ./build/fortransky

• JSON parser is hand-rolled and lightweight — not a full schema-driven parser
• relay-raw only surfaces app.bsky.feed.post create ops; other collections
  are filtered out at the normalize stage
• Stream view shows raw DIDs; handle resolution (DID → handle lookup) is not
  yet implemented
• The TUI is line-based (type command + Enter), not raw keypress
• m and j for stream control are home view commands — go b back to home
  first if you are in the post list

v1.1 — Native Rust firehose decoder integrated. relay_raw_tail.py prefers
firehose_bridge_cli when found. CMakeLists wires Rust staticlib into the
Fortran link. JWT field lengths bumped to 1024 to fit full AT Protocol tokens.
JSON key scanner depth-tracking fix (was matching nested keys before top-level
feed array).

v1.0 — Like, repost, quote-post actions. URL facet emission.

v0.9 — Typed decode layer (decode.f90). Richer post semantics in TUI.

v0.7 — C libcurl bridge replacing shell curl. Saved session support.
Stream mode toggle (jetstream / relay-raw).