Agent Architecture Crystallizes: CLI Convergence, Multi-Agent Orchestration, and the Harness Layer
The CLI Convergence Is Real and Architecturally Significant
In a single week, Stripe Projects.dev, Ramp, Visa, ElevenLabs, Sendblue, Kapso, Resend, and Google Workspace all launched CLIs explicitly designed for AI agent operation. Stripe's is the highest-leverage example: stripe projects add posthog/analytics creates an account, provisions API keys, and sets up billing in a single subprocess call. The key design decision: Stripe built this to be 'deterministic enough for agents to operate safely' — meaning your next teammate to run stripe projects init might be an agent, not a human.
This displaces the MCP-adapter-first approach for service provisioning. Instead of maintaining typed client libraries or MCP adapters per vendor, you're looking at a subprocess execution layer: spawn process, pipe structured input, parse stdout, handle exit codes. The contract is dramatically simpler than HTTP-based integration. The trade-off is real: you lose typed error responses, retry semantics are unclear, and you're managing process lifecycles instead of HTTP connections. For provisioning and configuration — unambiguously better. For hot-path data operations — stick with SDKs.
Multi-Agent Orchestration Has a Reference Architecture
Cline Kanban solves the two problems that make multi-agent coding painful: sequential waiting and merge conflicts. Each agent gets an isolated git worktree (not a branch — a full working directory), tasks sit on a kanban board with dependency edges, and agents work in parallel. When a dependency chain completes, you review the diff and merge. It supports Claude Code, Codex, and Cline as backends — model-agnostic at the orchestration layer. The open question is semantic conflicts: two agents making logically incompatible changes to different files that both pass individual tests. For cleanly decomposable feature work, expect 3-5x wall-clock time reduction.
Anthropic's generator-evaluator harness is the other pattern to internalize. One agent generates code, another evaluates it against explicit grading criteria, and structured feedback flows back — a GAN-inspired loop that addresses the two actual failure modes of single-agent coding: context drift (agents losing coherence during long tasks) and poor self-evaluation (agents can't judge their own output quality). This is fundamentally different from asking the same model to review its own work.
Intercom's production deployment validates both patterns at scale: 13 plugins, 100+ composable skills, a hooks-based integration layer that intercepts Claude Code's execution at well-defined points. This is platform engineering for AI agents — middleware, not prompting. Their architecture maps cleanly to a three-layer context system that GitHub's analysis of 2,500+ instruction files also surfaced: repo-level rules, path-specific instructions, and custom agent personas via .agent.md files.
The RL Loop Is the New Moat
NVIDIA's ProRL Agent result is underreported: by fully decoupling rollout (I/O-bound agent execution) from optimization (GPU-bound gradient computation), they nearly doubled Qwen 8B's SWE-Bench Verified score from 9.6% to 18.0%. The insight: published agent benchmarks may be measuring infrastructure quality as much as model quality. Cursor's 5-hour Composer 2 checkpoint cadence is the productized version — they deploy checkpoints to production, observe user accept/reject as reward signal, retrain, and ship. Model quality compounds daily when you close this loop.
The harness layer — middleware, memory, orchestration, tool interfaces — is where differentiation lives now, not the base model.
What to do
Prototype a CLI-subprocess integration layer wrapping Stripe Projects.dev and at least one other vendor CLI as tool primitives for your agents
Create .github/copilot-instructions.md with your coding conventions, security defaults, and prohibited patterns for your 3 most active repos
Evaluate Cline Kanban for your next multi-task feature sprint
Read Anthropic's full harness design article and prototype a generator-evaluator loop for your highest-value AI-assisted workflow