| --- |
| tags: |
| - codesync |
| - devshub |
| - decision-model |
| - developer-tools |
| pipeline_tag: text-classification |
| --- |
| |
| # CodeSync Knack |
|
|
| **The free, private judgment model behind CodeSync.** |
|
|
| Every time you send CodeSync a message or it runs a shell command, it makes dozens of quick |
| calls: Is this command risky? Will it run forever? Are you asking to continue earlier work? |
| Is this a question or a task? Which mode fits? Knack makes those calls on your own machine, |
| in about 10 milliseconds. |
|
|
| - **Free.** Ships with every CodeSync install. No API key, no account, no usage limits. |
| - **Private.** Runs locally. Your prompts and commands never leave your machine to be judged. |
| - **Fast.** About 10 ms per decision on a GPU, about 250 ms on a plain CPU. |
| - **Small.** About 1 GB on disk. Installs itself in the background after CodeSync starts. |
| - **Accurate where it matters.** Trained on real CodeSync sessions, with extra focus on the |
| rare cases that cost the most when missed: destructive deletes, commands that never exit, |
| resuming interrupted work, refactor / test / documentation requests. |
|
|
| ## Results |
|
|
| Measured on CodeSync's own judgments (version v3, November 2026): |
|
|
| | Benchmark | Knack v3 | What it measures | |
| |---|---:|---| |
| | Hand-labelled set | **97.9%** | 233 decisions labelled by hand | |
| | Held-out set | **95.5%** | 3,267 decisions from real sessions, never trained on | |
| | Rare-case set | **93.7%** | 4,120 decisions on the hardest, rarest cases | |
| | Latency | **13 ms** | median per request on a laptop GPU | |
|
|
| ## How to get it |
|
|
| Install CodeSync. That's it. |
|
|
| ```bash |
| curl -fsSL https://app.devshub.ai/install.sh | bash |
| ``` |
|
|
| The installer stays as fast as before. On first start, CodeSync downloads Knack in the |
| background and keeps working while it does. Once Knack is ready it becomes CodeSync's first |
| judgment engine, and new versions are picked up automatically. |
|
|
| To turn it off: `CODESYNC_KNACK_DISABLED=1`. |
|
|
| ## What it decides |
|
|
| Knack answers CodeSync's fixed set of 29 decisions: |
|
|
| - **Every turn (21):** task intent, routing and reasoning depth, plan / ask / build mode, |
| new task vs continuing work, resume requests, screencast start and stop, browser and |
| messaging needs, whether the request is chat or a task, and more. |
| - **Every shell command (8):** risk level, activity type, long-running or not, whether it |
| verifies, mutates the repo, deploys, needs a running app, or starts a server. |
|
|
| It only answers the questions it was trained on. Anything else is passed to CodeSync's |
| cloud judgment service, so a new kind of question never gets a guess. |
|
|
| ## Files |
|
|
| | File | Purpose | |
| |---|---| |
| | `manifest.json` | current version, archive URL, sha256 (read by CodeSync) | |
| | `knack-<version>.tar.gz` | the model folder | |
|
|
| Built by [DevsHub](https://app.devshub.ai) for [CodeSync](https://app.devshub.ai). |
|
|
