NextUI.AI.Harnesses.Cli

Structured CLI agent harnesses for the NextUI AI orchestration system (design V6): instead of swallowing raw stdout, each harness speaks the CLI's official machine protocol and maps its frames onto the stable NextUI agent event contract (13 event kinds).

• CodexAppServerHarness (nextui.cli2:codex-cli) — drives codex app-server (line-delimited JSON-RPC over stdio, without the "jsonrpc":"2.0" header field): initialize handshake, thread/start + turn/start lifecycle, streamed item/* notifications, protocol-native approvals (server→client requests answered through INextUIPermissionBroker), turn/steer interjections and turn/interrupt.
• ClaudeStreamJsonHarness (nextui.cli2:claude-code) — drives claude -p --input-format stream-json --output-format stream-json --verbose --include-partial-messages (plain JSONL in both directions, no id correlation): system/init session id capture, token-level stream_event deltas (text/thinking), whole assistant/user messages for read-only tool visibility, one result per submitted user message; queued interjections go out as the next stdin user message after the current round. The executable name is parameterized — the same harness drives the protocol-isomorphic openclaude CLI.
• GeminiStreamJsonHarness (nextui.cli2:gemini-cli) — drives gemini --output-format stream-json --prompt <text> (one-way JSONL on stdout; the prompt travels as argv and stdin is closed at start): init session id capture, assistant message delta chunks, tool_use/tool_result read-only tool visibility, error journal entries, one result per process. One run = one process = one prompt; interjections cannot be delivered and are journaled as rejected (contract-documented honest drop). Frame shapes are documentation-calibrated (no real binary was available); the contract lists the pending real-binary calibration items.

The package depends only on NextUI.AI.Abstractions plus the BCL (System.Diagnostics.Process, System.Text.Json, System.Threading.Channels). Per-backend compatibility contracts live in docs/agents/harness-contracts/ in the NextUI repository.