Adapters Overview

Adapters are the bridge between Paperclip's orchestration layer and agent runtimes. Each adapter knows how to invoke a specific type of AI agent and capture its results.

How Adapters Work

When a heartbeat fires, Paperclip:

1. Looks up the agent's adapterType and adapterConfig
2. Calls the adapter's execute() function with the execution context
3. The adapter spawns or calls the agent runtime
4. The adapter captures stdout, parses usage/cost data, and returns a structured result

Built-in Adapters

Hermes local vs gateway

Use hermes_local when Paperclip should start the local hermes CLI on the same host for each heartbeat. Use hermes_gateway when Hermes is already running as an HTTP/SSE API server and Paperclip should call that server instead of spawning a process. Both type keys are stable built-ins.

The unified Hermes package owns both built-in adapters. The older @paperclipai/adapter-hermes-gateway package remains only as a deprecated compatibility shim that re-exports the gateway entrypoints for one release. New plugin overrides should target @paperclipai/hermes-paperclip-adapter and set the desired type key (hermes_local or hermes_gateway).

External (plugin) adapters

These adapters ship as standalone npm packages and are installed via the plugin system:

External Adapters

You can build and distribute adapters as standalone packages — no changes to Paperclip's source code required. External adapters are loaded at startup via the plugin system.

# Install from npm via API
curl -X POST http://localhost:3102/api/adapters \
  -d '{"packageName": "my-paperclip-adapter"}'

# Or link from a local directory
curl -X POST http://localhost:3102/api/adapters \
  -d '{"localPath": "/home/user/my-adapter"}'

See External Adapters for the full guide.

Adapter Architecture

Each adapter is a package with modules consumed by three registries:

my-adapter/
  src/
    index.ts            # Shared metadata (type, label, models)
    server/
      execute.ts        # Core execution logic
      parse.ts          # Output parsing
      test.ts           # Environment diagnostics
    ui-parser.ts        # Self-contained UI transcript parser (for external adapters)
    cli/
      format-event.ts   # Terminal output for `paperclipai run --watch`

Choosing an Adapter

• Need a coding agent? Use claude_local, codex_local, acpx_local, opencode_local, hermes_local, or install droid_local as an external plugin
• Need the richest live run feedback (especially for sandbox workers)? Use acpx_local — see Feedback granularity
• Need Hermes on another host or already running as a service? Use hermes_gateway
• Need to run a script or command? Use process
• Need to call a custom external service? Use http
• Need something custom? Create your own adapter or build an external adapter plugin

Feedback Granularity

Adapter choice determines how much structured, live detail a run's transcript can show while the agent is still working. Every adapter's stdout is streamed to the run log and rendered live in the UI — including runs on sandbox execution targets, whose logs are tailed and delivered incrementally — but the granularity of what you see depends on the event stream the adapter emits.

Rough tiers, richest first:

1. acpx_local — full structured event stream. ACPX emits a JSONL event per meaningful runtime moment: acpx.session (agent, mode, session identity), acpx.status (progress text plus context-window usage), acpx.text_delta (assistant/thinking token deltas), acpx.tool_call (tool title, call id, and status updates as the call progresses), acpx.result (stop reason summary), and acpx.error (code, message, retryability). The transcript renders these as live-updating message, thinking, tool, and status blocks, and repeated acpx.tool_call status updates fold into a single tool card instead of stacking duplicates.
2. CLI wrappers (claude_local, codex_local, cursor, opencode_local, …). These parse each CLI's own streaming JSON output. You get assistant text, tool calls/results, and a final usage/cost summary, but granularity is limited to what the CLI prints — some emit tool progress, others only call/finish pairs.
3. Generic adapters (process, http). Plain stdout/stderr lines with no structured transcript — you see raw output only.

Recommendation: for sandbox workers, prefer acpx_local. Sandbox run logs are streamed live, so the richer the event stream, the more useful the live transcript and status line are while a remote run is in flight. ACPX's status events (including context usage) and incremental tool-call updates give the closest thing to watching the agent work locally.

UI Parser Contract

External adapters can ship a self-contained UI parser that tells the Paperclip web UI how to render their stdout. Without it, the UI uses a generic shell parser. See the UI Parser Contract for details.