Jaroslav Beneš
1d3f6c450b
Four features, plus the schema machinery they needed. **Schema sync.** The first live instance had data in it, and create_all only creates missing *tables* -- a new column silently never appeared. db/migrations.py now diffs the declared models against the database and ALTER TABLE ... ADD COLUMN for what is missing, deriving a backfill default from the column type (SQLite refuses a NOT NULL column without one, and a Python-side `default=dict` cannot be expressed in DDL). Verified against a copy of the live database: eight changes applied, all rows preserved, second run a no-op. Renames, drops and retypes are still manual and say so. **Permissions.** A flat set of named booleans: an instance baseline widened by each group the user belongs to. A group grants and never denies -- with denies, "why can this user not do X" cannot be answered without simulating every group. Admins bypass entirely, because an admin can grant it back to themselves in two clicks and pretending otherwise is theatre. Model *access* is separate: public, or granted to groups. The picker is not the boundary -- switching a chat to a model you cannot reach is a 403. **Model settings.** Ordering, pinned-first, an instance default and a per-user default, display names, descriptions, capability flags, and uploaded images. Images are stored and served locally rather than by URL: a remote URL makes every page render a request to a third party. Uploads are validated by magic number, not the declared content type, and stored under a random name. Models with no image get a generated initial whose hue is derived from the model id, so it is stable. **Reasoning display.** Streams into its own collapsible block above the answer, labelled "Thought for 14 seconds", collapsed once finished, and never replayed as context on the next turn. Two sources: the reasoning_content delta field, and <think> tags inline in content -- the latter needs a streaming splitter because the tags arrive split across chunks. Models emitting no reasoning show nothing, via a :has() rule rather than JavaScript. Verified against qwen35-9b on llama-swap: 694 reasoning events, 52 answer tokens, cleanly separated. Two bugs found and fixed while testing: - A bare `Mapped[list]` relationship is treated by SQLAlchemy as a scalar and returns None instead of []. It needs the element type. - FastAPI substitutes the default for an empty form value, so with `x: str | None = Form(None)` a submitted `x=` is indistinguishable from an absent field. That silently broke clearing a system prompt or a temperature. update_chat now reads the raw form and checks key presence. 143 tests, ruff clean. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
A self-hosted web UI for your language models, written in Python.
Talks to anything that speaks the OpenAI API. Themed after Middle-earth.
Lembas is the Elvish waybread — one bite sustains a traveller for a day's march. The capitals hide what it runs on: LLeMbas.
Why this exists
Most self-hosted LLM front-ends are large JavaScript applications with a Python
API bolted underneath. LLeMbas is the other way round: server-rendered
Python, with htmx and a little Alpine for interactivity. There is no
package.json, no bundler, no build step, and nothing is fetched from a CDN at
runtime. Clone it, pip install -e ., run it.
Features
Working now
- Chats — streaming replies, Markdown with server-side syntax highlighting, copy and regenerate, automatic chat titles, per-chat system prompt and sampling settings
- Reasoning display — thinking from reasoning models streams into its own collapsible block, labelled with how long it took, and is never replayed as context
- Folders — arbitrarily nested, delete a folder without losing the chats inside it
- OpenAI connections — point at OpenAI, LM Studio, vLLM, llama.cpp, llama-swap, Ollama or OpenRouter; models are discovered and cached
- Model settings — ordering, pinned models, an instance default and a per-user default, custom names and descriptions, uploaded model images
- Users, groups & permissions — per-group grants that union rather than override, and model access restricted to chosen groups
- Accounts — first account becomes the administrator, argon2 password hashing, revocable server-side sessions, self-service password change, admin-managed accounts
- Admin settings — open or close registration from the UI, stored in the database and effective immediately
- Two themes — Moria (dark) and Shire (light), switchable per user
Planned
File upload, vision and PDFs · built-in tools with admin settings · custom tools and MCP servers · agentic execution (local and over SSH) · image generation.
Quick start
git clone https://git.houmeres.sk/Houmeres/LLeMbas.git
cd LLeMbas
python -m venv .venv && . .venv/bin/activate
pip install -e ".[dev]"
cp .env.example .env
lembas secret-key # paste the result into LEMBAS_SECRET_KEY
lembas serve # http://127.0.0.1:8080
Open the address and create the first account — it becomes the administrator.
Then go to Admin → Connections and add an endpoint. For a local runner that
is usually http://localhost:1234/v1 with no API key. Press Test & refresh
and its models appear in the chat model picker.
The vendored browser libraries (htmx, Alpine) are committed, so no network access is needed to run. To re-fetch or bump them:
python scripts/fetch_vendor.py --update.
Configuration
All variables are prefixed LEMBAS_ and can live in .env. See
.env.example for the annotated list.
| Variable | Default | Purpose |
|---|---|---|
LEMBAS_SECRET_KEY |
generated | Signs sessions and encrypts stored API keys. Set this. A generated key changes every restart, signing everyone out and making stored API keys unreadable. |
LEMBAS_DATA_DIR |
./data |
SQLite database and uploads. |
LEMBAS_HOST / LEMBAS_PORT |
127.0.0.1 / 8080 |
Bind address. |
LEMBAS_ALLOW_SIGNUP |
true |
Whether new users may register themselves — the initial value only. Once set under Admin → General the stored setting wins. The first account is always an admin regardless. |
LEMBAS_DEFAULT_THEME |
moria |
moria (dark) or shire (light). |
LEMBAS_SESSION_TTL |
2592000 |
Session lifetime in seconds. |
LEMBAS_REQUEST_TIMEOUT |
300 |
Seconds to wait on an upstream model. |
Commands
lembas serve # run the server
lembas info # where data lives, what is configured
lembas secret-key # generate a value for LEMBAS_SECRET_KEY
lembas create-admin # create or promote an administrator
How it fits together
Browser ──form POST──▶ FastAPI ──▶ SQLite
▲ │
│ └──httpx──▶ any OpenAI-compatible endpoint
└──── server-sent events ◀───────────────┘ (streamed reply)
Sending a message stores the turn and returns two HTML fragments: the user's
bubble and an empty assistant bubble carrying an sse-connect. That opens a
server-sent event stream which appends tokens as they arrive, then replaces the
whole bubble with the finished, Markdown-rendered version. Rendering and
highlighting happen in Python, so the streamed and final views cannot disagree.
src/lembas/
api/ routes: auth, chats, folders, admin, pages
db/models/ SQLAlchemy schema
security/ password hashing, sessions
services/ llm client, chat orchestration, markdown, crypto, sse
web/ Jinja templates and static assets
assets/ SVG artwork masters
scripts/ artwork generator, vendored-JS fetcher
deploy/ systemd unit and nginx vhost for a real install
Development
pytest # test suite
ruff check . # lint
python scripts/build_artwork.py # regenerate the SVG artwork
python scripts/fetch_vendor.py # verify vendored JS against the lockfile
There is no Alembic. The schema is SQLite-only and synchronised at startup:
missing tables and missing columns are added automatically, so adding a field to
a model needs nothing but a restart. Renames, drops and retypes are still manual
— see CLAUDE.md.
Artwork
The logo, favicon and banner are original vector work, generated by
scripts/build_artwork.py so the mallorn leaf stays
identical across every size it appears at. The wordmark is
Source Serif 4 (SIL OFL 1.1)
converted to outlines — a README banner cannot load a webfont, and <text>
would render in whatever serif the reader happens to have.
Licence
A note on the theme
This is an independent hobby project, themed as an affectionate nod to J.R.R. Tolkien's world. It is not affiliated with, endorsed by, or connected to the Tolkien Estate, Middle-earth Enterprises, or any related rights holder. All artwork here is original.