pi-deepseek-reasoning-chain-fix

Pi extension that keeps DeepSeek reasoning working across tool-calling turns.

DeepSeek requires reasoning_content on every assistant message once the history contains tool calls. This extension fixes outbound requests so the field is always present and the real reasoning text survives between turns. Without it, DeepSeek stops reasoning (blank chain) or errors after the first tool call.

Install

From npm:

pi install npm:@amartinr/[email protected]

From GitHub:

pi install git:github.com/amartinr/[email protected]

Manual copy (single-file source, for development):

cp src/index.ts ~/.pi/agent/extensions/pi-deepseek-reasoning-chain-fix.ts

Then run /reload in pi.

Apply to the models you list in config.json — typical DeepSeek ids like deepseek/deepseek-v4-flash (direct or behind a gateway such as LiteLLM) work out of the box.

Configuration

The extension applies only to the model ids listed in ~/.pi/agent/extensions/pi-deepseek-reasoning-chain-fix/config.json:

{
  "models": [
    "deepseek/deepseek-v4-flash",
    "deepseek/deepseek-v4-pro"
  ],
  "replayReasoning": true
}

• models — model ids the fix applies to; exact or prefix match (case-insensitive), so "deepseek/" covers every deepseek-routed model. An empty or missing list leaves the extension inert — the safe default.
• replayReasoning — true (default): the real reasoning text is replayed on continuations (chaining). false: compliance only — a " " placeholder is sent to satisfy DeepSeek's contract, without chaining the real text.

Override the config path with PI_DEEPSEEK_REASONING_CONFIG. The load log reports the active ids and the mode.

Development

npm install          # dev dependencies
npm run build        # src/ -> dist/
npm run verify       # unit checks against the built artifact
node verify-live.mjs # live A/B against a gateway
npm pack --dry-run   # inspect the published tarball (dist only)

Versioning

Semver via npm version patch|minor|major (commit + vX.Y.Z tag). Bumps follow conventional commit types: fix: → patch, feat: → minor, breaking → major (pre-1.0: minor).

License

MIT