Feature request: expose control-stdin pipe in headless mode for external integrators

[zts212653]

Context

Cat Café (multi-agent orchestrator) integrates DARE via headless CLI mode. Currently we use --auto-approve to bypass approval prompts, but this prevents us from implementing fine-grained approval control from the orchestrator side.

Request

When running in --headless mode, allow external integrators to write to DARE's stdin using the client-control-stdin.v1 protocol to:

1. Grant/deny approvals selectively (approvals:grant, approvals:deny) instead of blanket --auto-approve
2. Query runtime state (status:get, actions:list)
3. Manage MCP tools at runtime (mcp:reload, mcp:show-tool)
4. List available skills (skills:list)

Current Behavior

• --headless mode outputs structured JSON events to stdout (works great)
• --control-stdin flag exists in the codebase (client/render/control.py) but it's unclear if it's fully wired up for external consumption
• External integrators currently have no way to send control commands during a headless session

Desired Behavior

# Integrator spawns DARE with stdin pipe
python -m client --adapter openrouter --model zhipu/glm-5 \
  run --task "do something" --headless --control-stdin

# Integrator can write to stdin:
echo '{"schema_version":"client-control-stdin.v1","id":"1","action":"approvals:list","params":{}}' > /proc/$PID/fd/0

Why This Matters

Without stdin control, integrators must choose between:

• --auto-approve (no safety boundary)
• No approval at all (task hangs on approval.pending)

The control-stdin protocol would allow orchestrators to implement their own approval policies while preserving DARE's audit trail.

Related

• Issue Feature request: session resume support for headless mode #184 (session resume) — another integration gap for external consumers
• Issue Gap Analysis: DARE example CLI vs Claude Code/Codex CLI（可集成性差距） #135 (gap analysis) — original integration assessment
• Cat Café F050 spec: docs/features/F050-a2a-external-agent-onboarding.md

[bouillipx]

Status update: this issue is already covered by merged PRs.

PR mapping:

• ✅ feat(client): implement headless event envelope v1 baseline #145: landed explicit --headless host mode + versioned headless event envelope baseline.
• ✅ feat(client): implement external control plane v1 baseline for issue #135 #151: landed --control-stdin bridge with host actions for
  • approvals:list/poll/grant/deny/revoke
  • mcp:list/reload/show-tool
  • skills:list
  • status:get
• ✅ feat(client): expose host capability discovery via actions:list for issue #135 #158: added explicit capability discovery actions:list.

This matches the requested control surface in this issue (selective approvals, runtime status queries, MCP runtime management, skills listing, and host-discoverable action surface).

[bouillipx]

All slices landed: --headless + --control-stdin fully implemented with tests and docs. Closing as completed.