v2.5.28 — pure-subagent agents + anti-deadlock gate message

What's new in v2.5.28

Pure-subagent agents on every provider + anti-deadlock planning-gate message.

🐻 Agents: spawn-only everywhere (was: main-agent leak on opencode)

All 6 matcha agents (planner, finder, auditor, reviewer, debugger, cleaner) are now mode: subagent in the canonical source — the previous mode: primary on the 4 read-only agents made opencode list them as Tab-switchable main agents, contradicting the spawn-only orchestration model.

Now the behavior is identical across every provider:

• opencode — mode: subagent → spawn-only via Task tool / @-mention, hidden from the Tab picker
• AGY / Antigravity — mainAgent: false → invoked behind the scenes
• Claude Code — transformed to Claude agent format

You can still @matcha-planner / @matcha-reviewer manually — they just won't appear as a main-agent option.

⛔ Planning gate: anti-deadlock deny message

Both deny messages (no plan + invalid plan) now state explicitly:

✅ Writing to .agents/plan/current.md is ALWAYS allowed — create the plan there now via Edit/WriteFile (that write is never blocked).

This cuts the panic loop where an agent, told to write a plan, tries alternate paths (Bash heredocs, other filenames) because the message didn't tell it the plan-file write itself is exempt.

✅ Validation

• 594/594 tests pass · copies consistent across all providers · build OK
• Version bumped to 2.5.28