Modes

Modes let you customize behavior, tools, and prompts for different use cases.

CoStrict ships with two built-in modes: Build and Plan. You can customize these or create your own.

---

Built-in Modes

Build

Build is the default mode with all tools enabled — the standard mode for development work.

StrictPlan

StrictPlan provides a complete planning workflow. See the StrictPlan documentation for details.

---

Switching Modes

Press Tab in a session to cycle through modes, or use the configured agent_cycle shortcut.

---

Configuring Modes

Modes can be configured in two ways.

JSON Configuration

In costrict.json:

costrict.json

{
  "$schema": "https://opencode.ai/config.json",
  "mode": {
    "build": {
      "model": "anthropic/claude-sonnet-4-5",
      "tools": {
        "write": true,
        "edit": true,
        "bash": true
      }
    },
    "plan": {
      "model": "anthropic/claude-haiku-4-5",
      "tools": {
        "write": false,
        "edit": false,
        "bash": false
      }
    }
  }
}

Markdown Configuration

Place Markdown files in:

• Global: ~/.config/costrict/modes/
• Project: .costrict/modes/

The filename becomes the mode name (e.g. review.md creates a review mode).

.costrict/modes/review.md

---
model: anthropic/claude-sonnet-4-5
temperature: 0.1
tools:
  write: false
  edit: false
  bash: false
---

You are in code review mode. Focus on:

- Code quality and best practices
- Potential bugs and edge cases
- Security considerations

Provide constructive feedback without making direct changes.

---

Configuration Options

Model

Override the default model for this mode:

costrict.json

{
  "mode": {
    "plan": {
      "model": "anthropic/claude-haiku-4-5"
    }
  }
}

Temperature

Control response randomness (0.0–1.0):

• 0.0–0.2 — Focused and deterministic, good for analysis and planning
• 0.3–0.5 — Balanced, good for general development
• 0.6–1.0 — More creative, good for brainstorming

costrict.json

{
  "mode": {
    "plan": { "temperature": 0.1 },
    "brainstorm": { "temperature": 0.7 }
  }
}

Prompt

Specify a custom system prompt file for the mode:

costrict.json

{
  "mode": {
    "review": {
      "prompt": "{file:./prompts/code-review.txt}"
    }
  }
}

Tools

Control which tools are available in this mode:

costrict.json

{
  "mode": {
    "readonly": {
      "tools": {
        "write": false,
        "edit": false,
        "bash": false,
        "read": true,
        "grep": true,
        "glob": true
      }
    }
  }
}

Available tools to configure:

Tool	Description
bash	Execute shell commands
edit	Modify existing files
write	Create new files
read	Read file contents
grep	Search file contents
glob	Find files by pattern
list	List directory contents
patch	Apply patches to files
webfetch	Fetch web page content

---

Custom Mode Examples

Debug Mode

.costrict/modes/debug.md

---
temperature: 0.1
tools:
  bash: true
  read: true
  grep: true
  write: false
  edit: false
---

You are in debug mode. Investigate and diagnose issues.

Focus on:
- Understanding the problem through careful analysis
- Using bash commands to inspect system state
- Reading relevant files and logs

Do not make any changes to files. Only investigate and report.

Docs Mode

costrict.json

{
  "$schema": "https://opencode.ai/config.json",
  "mode": {
    "docs": {
      "prompt": "{file:./prompts/documentation.txt}",
      "tools": {
        "write": true,
        "edit": true,
        "bash": false,
        "read": true,
        "grep": true,
        "glob": true
      }
    }
  }
}

---

Mode Reference

Mode	Use Case
Build	Full development — all tools enabled
Plan	Analysis and planning — no file changes
StrictPlan	Complete requirements analysis and task planning workflow
Review	Code review — read-only access
Debug	Troubleshooting — bash and read tools enabled
Docs	Documentation writing — file ops, no shell commands