Kimi prompt not applied to kimi-for-coding models k3 / k3-256k (falls back to default) #42059

Description

SystemPrompt.provider() in packages/opencode/src/session/system.ts selects the dedicated Kimi system prompt (prompt/kimi.txt, added in #20259 by Moonshot AI) only when the model API id contains the substring kimi:

if (model.api.id.toLowerCase().includes("kimi")) return [PROMPT_KIMI]
return [PROMPT_DEFAULT]

However, the official kimi-for-coding provider now serves its current flagship models under bare ids that do not contain kimi:

So the very same Kimi K3 model gets the Moonshot-tuned prompt when called via the Moonshot provider, but the generic fallback prompt when called via the official Kimi for Coding endpoint — which is likely the most common way K3 is used.

Expected behavior

Kimi-series models served by the official Kimi providers (kimi-for-coding, moonshotai, moonshotai-cn) should consistently use PROMPT_KIMI, regardless of whether the model id itself happens to contain the string kimi.

Suggested fix

Match on providerID in addition to the model id, e.g.:

if (model.api.id.toLowerCase().includes("kimi") || model.providerID.includes("kimi"))
  return [PROMPT_KIMI]

(Matching bare k3 by id substring would risk false positives, so keying off the provider seems safer.)

Environment

• opencode 1.18.15 (desktop CLI)
• Model: kimi-for-coding/k3
• Verified by inspecting the compiled binary: the provider() selection checks only model.api.id, and the resulting system prompt for a kimi-for-coding/k3 session starts with the default prompt text (You are opencode, an interactive CLI tool...) instead of the Kimi one (You are OpenCode, an interactive general AI agent...).