Loom

Local-only desktop test harness for experimenting with LLM context-window editing. Edit any message in a conversation, fork it as a new branch, compare responses side-by-side. Think of it as git rebase -i for your prompts.

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Status

• v0.1.0-mvp — linear chat, branching via edit-and-fork, git-style commit graph with colored lanes, side-by-side word diff between sibling responses, JSON-on-disk session storage.
• Provider: Ollama on http://localhost:11434 (native /api/chat).
• Platform: desktop (Windows verified; macOS/Linux untested but scaffolded).

Features

• Edit any turn, fork a branch. Editing never mutates — every change creates a sibling turn on a new branch. History is always recoverable.
• Commit-graph sidebar. Every session's DAG rendered as a compact git-style graph. Click any node to jump to its branch.
• Per-branch colors. Stable assignment by branch creation order — branch tabs, lane edges, and node strokes share one identity.
• Side-by-side word diff between sibling responses via jsdiff.
• Streaming with metadata. Token counts (prompt + reply), durations, and the exact outbound request body are persisted with every assistant turn.
• Sampling knobs (temperature, top_p, num_ctx, seed) per-send.
• Atomic JSON storage (temp-write + fsync + rename; .bak rotated on every save).
• Remembers window geometry across restarts.
• Rolling context window. Set a per-session turn limit; the oldest non-pinned turns drop out of the outbound request. Excluded turns stay visible in the timeline (dimmed, badged) so you can change the limit or pin one and they re-enter context.
• Pin turns. Click the pin icon on any turn to keep it in the outbound context regardless of the limit. The root system turn is always included by policy.

Phase-7+ features (prefill via /api/generate + raw:true, raw-JSON request editor, swipes, system-prompt library, multimodal) are planned but not in v0.1.0.

Prerequisites

• Rust (stable, MSVC host on Windows) — install via rustup.
• Visual Studio 2022 Build Tools with the Desktop development with C++ workload (Windows only — for the MSVC linker Tauri needs).
• Node.js 20+ and npm.
• Ollama — install from ollama.com and pull at least one chat model:

  ollama pull llama3.1:8b
  

• WebView2 runtime (ships with Windows 11; installer otherwise pulls it automatically).

Run

cd <this directory>
npm install
npm run tauri dev

First run compiles the Rust dependency graph (~10 minutes, one-time). Subsequent runs start in seconds.

Make sure Ollama is running in another terminal:

ollama serve

Build

npm run tauri build

Outputs a Windows installer under src-tauri/target/release/bundle/.

How Loom thinks about sessions

Every session is one JSON file under your user app-data directory:

• Windows: %APPDATA%\loom\sessions\<ulid>.loom.json
• macOS: ~/Library/Application Support/dev.loom.app/sessions/
• Linux: ~/.local/share/dev.loom.app/sessions/

A session is a small DAG:

• Turn — one message (system / user / assistant / tool). Immutable once written; identified by a ULID. Stores role, content, created_at, optional generated_by metadata (endpoint, model, exact outbound request body, token counts, durations).
• Branch — a named pointer to a head turn, optionally tagged with forked_at (the turn the branch diverged from) and parent_branch.
• head_branch — the branch currently being read/written.

Editing a turn creates a sibling turn (same parent, same role, new content) and a new branch pointing at it. head_branch advances to the new branch. The edited turn itself is never mutated — old responses stay visible under their original branches.

Session file format (v1)

{
  "loom_schema": 1,
  "session": {
    "id": "sess_01H...",
    "title": "Exploring refusal after persona shift",
    "created_at": "2026-04-16T12:00:00Z",
    "model": "llama3.1:8b",
    "default_options": { "temperature": 0.7 },
    "default_endpoint": "http://localhost:11434/api/chat"
  },
  "turns": {
    "t_01H...": {
      "id": "t_01H...",
      "parent": null,
      "role": "system",
      "content": "You are a helpful assistant.",
      "created_at": "2026-04-16T12:00:00Z",
      "generated_by": null,
      "annotations": [],
      "swipe_group": null
    }
  },
  "branches": {
    "b_01H...": {
      "name": "main",
      "head": "t_01H...",
      "created_at": "2026-04-16T12:00:00Z",
      "parent_branch": null,
      "forked_at": null
    }
  },
  "head_branch": "b_01H..."
}

All fields except id, parent, role, content, created_at are optional and may be absent in older files.

Keyboard

• Ctrl+Enter in the composer — send.
• Double-click the session title — rename.
• Esc inside any modal — cancel.

Context window

• On session create, optionally set a context limit (turn count). Leave blank for unlimited.
• Change it later by clicking the ctx: … value in the session header.
• Click the pin icon on any turn to exempt it from rolling out.
• The root system turn is always in context even if unpinned — it anchors the whole conversation.

Layout

┌──────────┬──────────────────────────────────────┐
│ Sessions │  [branch tabs]                       │
│ sidebar  ├──────────────────────────────────────┤
│          │  Timeline of turns        │ Commit   │
│          │  (cards, Edit on hover)   │ graph    │
│          ├──────────────────────────────────────┤
│          │  Composer (CodeMirror + sliders)     │
└──────────┴──────────────────────────────────────┘

Development

Run the full verification matrix before a commit:

cargo test --manifest-path src-tauri/Cargo.toml
cargo clippy --manifest-path src-tauri/Cargo.toml --all-targets -- -D warnings
npm run build
npx tsc --noEmit

License

MIT — see LICENSE.