[FEATURE]: GUI for per-model profile/context parameters (system prompt, temperature, context window)

Summary

• I have searched for existing issues before filing this

Allow users to configure per-model context parameters (system prompt / "bio", temperature, max tokens, context window size, reasoning effort, and more) directly from the new GUI — without touching opencode.jsonc.

---

Problem

OpenCode supports many LLMs with wildly different capabilities, but configuring them requires manual JSON editing. Users who aren't comfortable in config files cannot:

• Set a custom system prompt / "bio" / profile for a specific model
• Override the context window size for models that report incorrect metadata
• Adjust temperature or reasoning effort for model-specific behavior
• Set model-specific parameters that control how the model generates output

---

This Request Subsumes Existing Issues

This intentionally broadens and subsumes the following open feature requests into a unified concept — a Model Profile:

Existing Issue	Scope	This Issue Adds
#40818	Context window per model	+ system prompt, temperature, max tokens
#41287	Show model capabilities in picker	+ editable fields, not just display
#42929	Show context window limit in TUI	+ writable profile config in GUI
#43601	设置大模型上下文窗口大小	+ full profile, not just window size
#38057	Incorrect context params for StepFun	+ the ability to override and fix it

---

Proposed Solution

A Model Profile Configuration UI accessible from:

• The model picker (... menu per model)
• Settings → Model Profiles
• A /profile slash command

Each profile:

{
  "model": "gpt-4o",
  "systemPrompt": "[custom bio/profile text]",
  "temperature": 0.7,
  "maxTokens": 4096,
  "contextWindow": 128000,
  "reasoningEffort": "medium"
}

Profiles must be:

• Named and persistent — saved to config
• Assignable per-model — one profile per model
• Editable from GUI — no JSON required
• Exportable/importable — share profiles across machines

---

Plugin Angle

A modelProfile(params) plugin hook would let plugins:

• Inject or override profile parameters dynamically
• Enforce enterprise compliance system prompts
• Cap maxTokens per model for cost control
• Sanitize system prompts via security plugins

---

OS

Cross-platform (Desktop + TUI).

---

🦙 Creative Monkey at FrenzyPenguin Media — open-source security hardening & privacy tools