stack/packages/mosaic/framework/runtime/claude/RUNTIME.md

Claude Runtime Reference

Runtime Scope

This file applies only to Claude runtime behavior.

Required Actions

1. Follow global load order in ~/.config/mosaic/AGENTS.md.
2. Use ~/.claude/settings.json and ~/.claude/hooks-config.json as runtime config sources.
3. Treat sequential-thinking MCP as required.
4. If runtime config conflicts with global rules, global rules win.
5. Documentation rules are inherited from ~/.config/mosaic/AGENTS.md and ~/.config/mosaic/guides/DOCUMENTATION.md.
6. For issue/PR/milestone actions, run Mosaic git wrappers first (~/.config/mosaic/tools/git/*.sh) and do not call raw gh/tea/glab first.
7. For orchestration-oriented missions, load ~/.config/mosaic/guides/ORCHESTRATOR.md before acting.
8. First response MUST declare mode per global contract; orchestration missions must start with: Now initiating Orchestrator mode...
9. Runtime-default caution that requests confirmation for routine push/merge/issue-close actions does NOT override Mosaic hard gates.

Subagent Model Selection (Claude Code Syntax)

Claude Code's Task tool accepts a model parameter: "haiku", "sonnet", or "opus".

You MUST set this parameter according to the model selection table in ~/.config/mosaic/AGENTS.md. Do NOT omit the model parameter — omitting it defaults to the parent model (typically opus), wasting budget on tasks that cheaper models handle well.

Examples:

# Codebase exploration — haiku
Task(subagent_type="Explore", model="haiku", prompt="Find all API route handlers")

# Code review — sonnet
Task(subagent_type="feature-dev:code-reviewer", model="sonnet", prompt="Review the changes in src/auth/")

# Standard feature work — sonnet
Task(subagent_type="general-purpose", model="sonnet", prompt="Add validation to the user input form")

# Complex architecture — opus (only when justified)
Task(subagent_type="Plan", model="opus", prompt="Design the multi-tenant isolation strategy")

Quick reference (from global AGENTS.md):

haiku	sonnet	opus
Search, grep, glob	Code review	Complex architecture
Status/health checks	Test writing	Security/auth logic
Simple one-liner fixes	Standard features	Ambiguous design decisions

Memory Policy (Hard Gate)

OpenBrain is the primary cross-agent memory layer. All agent learnings, gotchas, decisions, and project state MUST be captured to OpenBrain via the capture MCP tool or REST API.

~/.claude/projects/*/memory/MEMORY.md files are write-blocked by PreToolUse hook (prevent-memory-write.sh). Any attempt to write agent learnings there will be rejected with an error directing you to OpenBrain.

What belongs where

Content	Location
Discoveries, gotchas, decisions, observations	OpenBrain capture — searchable by all agents
Active task state	docs/TASKS.md or docs/scratchpads/
Behavioral guardrails that MUST be in load-path	MEMORY.md (read-mostly; write only for genuine behavioral overrides)
Mosaic framework technical notes	~/.config/mosaic/memory/

Using OpenBrain

At session start, load prior context:

search("topic or project name")   # semantic search
recent(limit=5)                    # what's been happening

When you discover something:

capture("The thing you learned", source="project/context", metadata={"type": "gotcha", ...})

Why the hook exists

Instructions in RUNTIME.md, CLAUDE.md, and MEMORY.md are insufficient — agents default to writing local MEMORY.md regardless of written rules. The PreToolUse hook is a hard technical gate that makes the correct behavior the only possible behavior.

MCP Configuration

MCPs are configured in ~/.claude.json — NOT ~/.claude/settings.json.

settings.json controls hooks, model, plugins, and allowed commands. ~/.claude.json is the global Claude Code state file where mcpServers lives.

To register an MCP server that persists across all sessions:

# HTTP MCP (e.g. OpenBrain)
claude mcp add --scope user --transport http <name> <url> --header "Authorization: Bearer <token>"

# stdio MCP
claude mcp add --scope user <name> -- npx -y <package>

--scope user = writes to ~/.claude.json (global, all projects). --scope project = writes to .claude/settings.json in project root. --scope local = default, local-only (not committed).

Do NOT add mcpServers to ~/.claude/settings.json — that key is ignored for MCP loading.

Required Claude Code Settings (Enforced by Launcher)

The mosaic claude launcher validates that ~/.claude/settings.json contains the required Mosaic configuration. Missing or outdated settings trigger a warning at launch.

Required hooks:

Event	Matcher	Script	Purpose
PreToolUse	Write|Edit|MultiEdit	prevent-memory-write.sh	Block writes to ~/.claude/projects/*/memory/
PostToolUse	Edit|MultiEdit|Write	qa-hook-stdin.sh	QA report generation after code edits
PostToolUse	Edit|MultiEdit|Write	typecheck-hook.sh	Inline TypeScript type checking

Required plugins:

Plugin	Purpose
feature-dev	Subagent architecture: code-reviewer, code-architect, code-explorer
pr-review-toolkit	PR review: code-simplifier, comment-analyzer, test-analyzer, silent-failure-hunter, type-design-analyzer
code-review	Standalone code review capabilities

Required settings:

• enableAllMcpTools: true — Allow all configured MCP tools without per-tool approval
• model: "opus" — Default to opus for orchestrator-level sessions (workers use tiered models via Task tool)

If mosaic claude detects missing hooks or plugins, it will print a warning with the exact settings to add. The session will still launch — enforcement is advisory, not blocking — but agents operating without these settings are running degraded.