feat(queen): Hive Queen Bee — native agent-building agent

feat(queen): Hive Queen Bee — native agent-building agent

Summary

Introduces Hive Coder (codename "Queen Bee"), a framework-native coding agent that builds complete Hive agent packages from natural language descriptions. This is a single-node, forever-alive agent inspired by opencode's while(true) loop — one continuous conversation handles the full lifecycle: understand, qualify, design, implement, verify, and iterate.

The agent is deeply integrated with the framework: it can discover available MCP tools at runtime, inspect sessions and checkpoints of agents it builds, run their test suites, and self-verify its own output. It ships with a dedicated MCP tools server (coder_tools_server.py) providing rich file I/O, fuzzy-match editing, git snapshots, and shell execution — all scoped to a configurable project root.

What's included

New: hive_coder agent (core/framework/agents/hive_coder/)

• agent.py — Goal with 4 success criteria and 4 constraints, single-node graph, HiveCoderAgent class with full runtime lifecycle (start/stop/trigger_and_wait)
• nodes/__init__.py — Single coder EventLoopNode with a comprehensive system prompt covering coding mandates, tool discovery, meta-agent capabilities, node count rules, implementation templates, and a 6-phase workflow
• config.py — RuntimeConfig with auto-detection of preferred model from ~/.hive/configuration.json
• __main__.py — Click CLI with run, tui, info, validate, and shell subcommands
• reference/ — Framework guide, file templates, and anti-patterns docs embedded as agent reference material

New: Coder Tools MCP Server (tools/coder_tools_server.py)

• 1500-line MCP server providing 15 tools: read_file, write_file, edit_file (with opencode-style 9-strategy fuzzy matching), list_directory, search_files, run_command, undo_changes, discover_mcp_tools, list_agents, list_agent_sessions, get_agent_session_state, get_agent_session_memory, list_agent_checkpoints, get_agent_checkpoint, run_agent_tests
• Path-scoped security: all file operations sandboxed to project root
• Git-based undo: automatic snapshots before writes with undo_changes rollback

Framework changes

• hive code CLI command — Direct launch shortcut for Hive Coder via cmd_code in runner/cli.py
• hive tui updated — Now discovers framework agents alongside exports/ and examples/
• Cron timer support — AgentRuntime now supports cron expressions (croniter) in addition to fixed-interval timers for async entry points
• Datetime in system prompts — prompt_composer._with_datetime() appends current datetime to all composed system prompts; EventLoopNode also applies it for isolated conversations
• max_node_visits default → 0 — Changed from 1 to 0 (unbounded) across NodeSpec and executor, matching the forever-alive pattern as the standard default
• TUI graph view — Timer display updated to show cron expressions and hours in countdown
• CredentialError handling — _setup() calls in TUI launch paths now catch and display credential errors gracefully

Tests

• New test_agent_runtime.py tests for cron-based timer scheduling

Architecture

User ──▶ [coder] (EventLoopNode, client_facing, forever-alive)
              │
              │  Tools: coder_tools_server.py (file I/O, shell, git)
              │         + meta-agent tools (discover, inspect, test)
              │
              └──▶ loops continuously until user exits

Single node. No edges. No terminal nodes. The agent stays alive and handles multiple build requests in one session — context accumulates across interactions.

Test plan

• hive code launches Hive Coder TUI successfully
• hive tui shows "Framework Agents" as a source option
• Agent can discover tools via discover_mcp_tools()
• Agent generates a valid agent package from a natural language request
• Generated packages pass AgentRunner.load() validation
• Cron timer tests pass (test_agent_runtime.py)
• Existing tests unaffected by max_node_visits default change