Splash 1.5.0

Splash now has a desktop app: download and run models, chat with them, and connect coding agents from one window. This release also adds local model loading, custom tools in the Responses API, faster decode on M5 and M6, and a fix for image requests that could crash the engine.

Splash for Mac

The desktop app includes its own runtime, shares models with the CLI, and supports:

Model downloads, switching, and launch settings.
Streaming chat, saved conversations, images, and reasoning controls.
Claude Code, Codex, OpenCode, Hermes, and Pi in your chosen project folder.
Menu bar controls and automatic update checks.

Requires Apple M3 or newer and macOS 26.4 or later. Download Splash, open the DMG, and drag Splash into Applications. Or install with Homebrew:

brew install --cask incoai/tap/splash-app

The app uses the default Hugging Face cache and does not inherit HF_HOME, HF_HUB_CACHE, or HF_TOKEN from your shell. Quitting it stops the model. GGUF files added locally run text only; use the CLI for a separate vision projector or local draft. MLX folders retain their vision support. (#610)

Speed and memory

Faster decode on M5 and M6. On a 32-core M5 Max, Qwen3.8-27B MLX 4-bit takes 11.7% less time per decode cycle with one request and 7.5–8.3% less with two to four. The 27B UD-Q4_K_M takes 2.2–4.4% less. On a 12-core M6, the 35B UD-Q2_K_XL takes 0.4–1.8% less. These are decode-cycle measurements; per-token gains for the batched 27B MLX are 1–2 percentage points smaller at three and four requests. Other GPU core counts were not measured end to end. (#235)
Lower MoE router memory. The 35B MLX 4-bit keeps its router quantized, saving 62 MB and reducing router reads from 84 MB to 22 MB per decode cycle. Quantized GGUF MoE routers also load; F16 routers remain unsupported. (#599)
Faster quantized kernels on M3, M4, and M5, including MLX 4-bit and several GGUF formats. These are kernel-level improvements; whole-model gains vary. (#600, #602)

Models and APIs

Local model files: serve a GGUF file or MLX directory with --model-dir, without contacting the Hub. Use --draft-model for a local DFlash2 draft and --mmproj for a GGUF vision projector. Otherwise, the matching draft must already be cached. (#338)
```
splash serve --model local/qwen \
  --model-dir /models/Qwen3.8-27B-GGUF/Qwen3.8-27B-UD-Q4_K_M.gguf \
  --draft-model /models/Qwen3.8-27B-DFlash2
```
Custom tools: Responses accepts freeform tools such as Codex's apply_patch and returns custom_tool_call items. Tool grammars are described to the model, not enforced; streamed tool input arrives when the call closes. (#426)
Request timings: Responses and Messages report prompt/decode counts, latency, rates, cached tokens, and draft counts. Messages also reports thinking-token usage. (#427)
Reasoning discovery: /v1/models reports supported reasoning efforts and defaults. (#610)
Pi prefix caching: splash pi enables later system messages when the model's template supports them, preserving reusable prefixes. (#609)
Shell completion: expands to 11 suggested models and completes local model, draft, and projector paths. (#338, #610)

Fixes

Image requests no longer trigger GPU timeouts on models whose experts stream from SSD. Image encoding runs before prefill in a separate GPU command, and image requests use Neural Engine prefill again. (#601, fixes #596)
Ctrl+C stops model downloads promptly. The next download from that repository cleans up interrupted partial files. (#610)
Browser chat asks for an API key only after a 401 response. (#610)
Update filelock to 4.2.4. (#603)

Upgrade

brew upgrade splash

Keep the CLI and desktop app on the same release.

Use full CLI option names: abbreviations such as --max-mem are no longer accepted.
Cached models: GGUF metadata is rebuilt from existing weights without downloading them again. Persistent caches for GGUF and MLX MoE models start fresh once; dense MLX caches remain usable. Switching between different App and CLI releases can repeat this.
Offline startup: if an older Splash downloaded your model and draft, run splash serve 1.5.0 for that family once with the Hub reachable before using it offline in the app or through --model-dir.
API clients: Responses and Messages add timings; Messages adds output_tokens_details.thinking_tokens. Responses' input_tokens_details.cache_write_tokens is always 0; compute uncached input as input_tokens - cached_tokens.
Numerical changes: kernel summation changes can slightly alter greedy output. On M5 and M6, output can also depend on concurrent requests.

Thanks to @zaiyang-zhang, @yannip1234, @ghisguth, and @lucaslie for contributions, and @shimbara for the detailed report. The zero-point kernel work builds on @ghisguth's #569.

Full changelog: 1.4.1...1.5.0

incoai/splash 1.5.0 Splash 1.5.0 on GitHub