Updated 2026-06-20
DeepSeek Reasonix config guide: treat `~/.reasonix/config.json` and Flash-to-Pro switching as the official baseline
This page targets a narrower support query than the broader Reasonix overview: how DeepSeek's own docs now tell you to launch Reasonix, where the first-run wizard stores the API key, and how the official Flash-first workflow escalates to stronger reasoning. That makes it a useful inner page for people searching specific Reasonix setup details instead of a general 'what is Reasonix' article.
1. Start Reasonix from the repository you actually want it to inspect
DeepSeek's official Reasonix page is explicit about the startup contract: enter the target project directory and run `npx reasonix code` there.
That repo-scoped launch matters because it defines what files the agent can read and edit. Many vague setup posts skip that boundary and leave users thinking the tool is broken when it simply started in the wrong directory.
cd /path/to/my-project
npx reasonix codeSources checked
- DeepSeek official Reasonix integration guide - Primary source for the startup command, config location, and slash-command routing.
2. The official first-run wizard stores the key in `~/.reasonix/config.json`
The most useful new DeepSeek-side detail is not just the startup command. It is that the first run prompts for the API key and persists it to `~/.reasonix/config.json`.
That gives support-query pages a concrete answer when users ask whether Reasonix uses an environment variable, a local config file, or both. DeepSeek's official page now gives a specific local file path.
{
"apiKey": "sk-..."
}3. DeepSeek's official workflow is Flash-first, then Pro when the task is harder
The docs say Reasonix defaults to DeepSeek V4 Flash for cost-efficient iteration. That is important because it frames Reasonix as a practical development loop, not a permanently maxed-out reasoning session.
DeepSeek then exposes two escalation paths: `/pro` for the next turn and `/preset max` for a stronger whole-session mode. That distinction gives search traffic a better answer than generic 'use Pro for hard tasks' advice.
| Command or mode | What it does | Best use |
|---|---|---|
| Default launch | Starts Flash-first for cheaper iteration | Broad repo exploration, fast edits, repeated tool loops |
| /pro | Arms V4 Pro for the next turn | One harder debugging or review step without changing the whole session |
| /preset max | Keeps the session on the strongest route | Longer architecture, debugging, or reasoning-heavy sessions |
4. Common Reasonix setup mistakes this official page helps avoid
The official DeepSeek page closes three easy failure loops: starting outside the target repository, assuming the key must stay only in an environment variable, and overpaying by forcing a Pro-heavy workflow for every turn.
If Reasonix still misbehaves after that baseline, compare `/guides/reasonix-deepseek-coding-agent` for broader workflow context and `/guides/deepseek-openclaw-setup` or `/guides/deepseek-oh-my-pi` for other official DeepSeek agent patterns.
5. Keep the business boundary clean
Reasonix is guide content, not a stocked product card. This page should not add or edit `/pricing`, `SUBSCRIPTION_PLANS`, payment configuration, or Supabase plan data.
The DeepSeek-first conversion path is still educational: understand the official Reasonix setup, then visit `/pricing` only if you need an in-stock DeepSeek API key route.
FAQ
What is the official command to start Reasonix with DeepSeek?
DeepSeek's official guide says to enter the project directory and run `npx reasonix code`.
Where does Reasonix store the DeepSeek API key?
The official DeepSeek page says the first-run wizard persists the key to `~/.reasonix/config.json`.
Does Reasonix default to DeepSeek V4 Pro?
No. DeepSeek's page says Reasonix defaults to DeepSeek V4 Flash for cost-efficient iteration, then lets you escalate when needed.
What is the difference between `/pro` and `/preset max` in Reasonix?
`/pro` is the lighter-weight escalation for the next turn, while `/preset max` is the stronger whole-session route described in DeepSeek's official setup page.
Does this guide make Reasonix a purchasable product on this site?
No. This page is support content for an official DeepSeek integration workflow. Purchasable products still depend on actual stocked inventory on `/pricing`.
The practical Reasonix setup rule is simple: start in the right repository, let the wizard write `~/.reasonix/config.json`, stay Flash-first by default, and escalate with `/pro` or `/preset max` only when the task actually needs it.
Related model comparisons
Continue from this guide into structured DeepSeek-first comparison pages with model tables, routing advice, and pricing context.