Technical guide for creating a new Paperclip agent adapter. Use when building a new adapter package, adding support for a new AI coding tool (e.g. a new CLI agent, API-based agent, or custom process), or when modifying the adapter system. Covers the required interfaces, module structure, registration points, and conventions derived from the existing claude-local and codex-local adapters.
Installation
Installer avec Codex ou Claude Copiez ce prompt, collez-le dans Codex, Claude ou un autre assistant, puis laissez-le vérifier la page du skill et l'installer pour vous.
Technical guide for creating a new Paperclip agent adapter. Use when building a new adapter package, adding support for a new AI coding tool (e.g. a new CLI agent, API-based agent, or custom process), or when modifying the adapter system. Covers the required interfaces, module structure, registration points, and conventions derived from the existing claude-local and codex-local adapters.
Creating a Paperclip Agent Adapter
An adapter bridges Paperclip's orchestration layer to a specific AI agent runtime (Claude Code, Codex CLI, a custom process, an HTTP endpoint, etc.). Each adapter is a self-contained package that provides implementations for three consumers: the server, the UI, and the CLI.
1. Architecture Overview
packages/adapters/<name>/
src/
index.ts # Shared metadata (type, label, models, agentConfigurationDoc)
server/
index.ts # Server exports: execute, sessionCodec, parse helpers
execute.ts # Core execution logic (AdapterExecutionContext -> AdapterExecutionResult)
parse.ts # Stdout/result parsing for the agent's output format
ui/
index.ts # UI exports: parseStdoutLine, buildConfig
parse-stdout.ts # Line-by-line stdout -> TranscriptEntry[] for the run viewer
build-config.ts # CreateConfigValues -> adapterConfig JSON for agent creation form
cli/
index.ts # CLI exports: formatStdoutEvent
format-event.ts # Colored terminal output for `paperclipai run --watch`
package.json
tsconfig.json
Three separate registries consume adapter modules:
Registry
Location
Interface
Server
server/src/adapters/registry.ts
ServerAdapterModule
UI
ui/src/adapters/registry.ts
UIAdapterModule
CLI
cli/src/adapters/registry.ts
CLIAdapterModule
2. Shared Types (@paperclipai/adapter-utils)
All adapter interfaces live in packages/adapter-utils/src/types.ts. Import from @paperclipai/adapter-utils (types) or @paperclipai/adapter-utils/server-utils (runtime helpers).
Return structured diagnostics, never throw for expected findings.
Use error for invalid/unusable runtime setup (bad cwd, missing command, invalid URL).
Use warn for non-blocking but important situations.
Use info for successful checks and context.
Severity policy is product-critical: warnings are not save blockers.
Example: for claude_local, detected ANTHROPIC_API_KEY must be a warn, not an error, because Claude can still run (it just uses API-key auth instead of subscription auth).
type — the adapter type key, stored in agents.adapter_type
label — human-readable name for the UI
models — available model options for the agent creation form
agentConfigurationDoc — markdown describing all adapterConfig fields (used by LLM agents configuring other agents)
Writing agentConfigurationDoc as routing logic:
The agentConfigurationDoc is read by LLM agents (including Paperclip agents that create other agents). Write it as routing logic, not marketing copy. Include concrete "use when" and "don't use when" guidance so an LLM can decide whether this adapter is appropriate for a given task.
exportconst agentConfigurationDoc = `# my_agent agent configuration
Adapter: my_agent
Use when:
- The agent needs to run MyAgent CLI locally on the host machine
- You need session persistence across runs (MyAgent supports thread resumption)
- The task requires MyAgent-specific tools (e.g. web search, code execution)
Don't use when:
- You need a simple one-shot script execution (use the "process" adapter instead)
- The agent doesn't need conversational context between runs (process adapter is simpler)
- MyAgent CLI is not installed on the host
Core fields:
- cwd (string, required): absolute working directory for the agent process
...
`;
Adding explicit negative cases improves adapter selection accuracy. One concrete anti-pattern is worth more than three paragraphs of description.
3.3 Server Module
server/execute.ts — The Core
This is the most important file. It receives an AdapterExecutionContext and must return an AdapterExecutionResult.
Required behavior:
Read config — extract typed values from ctx.config using helpers (asString, asNumber, asBoolean, asStringArray, parseObject from @paperclipai/adapter-utils/server-utils)
Build environment — call buildPaperclipEnv(agent) then layer in PAPERCLIP_RUN_ID, context vars (PAPERCLIP_TASK_ID, PAPERCLIP_WAKE_REASON, PAPERCLIP_WAKE_COMMENT_ID, PAPERCLIP_APPROVAL_ID, PAPERCLIP_APPROVAL_STATUS, PAPERCLIP_LINKED_ISSUE_IDS), user env overrides, and auth token
Resolve session — check runtime.sessionParams / runtime.sessionId for an existing session; validate it's compatible (e.g. same cwd); decide whether to resume or start fresh
Render prompt — use renderTemplate(template, data) with the template variables: agentId, companyId, runId, company, agent, run, context
Call onMeta — emit adapter invocation metadata before spawning the process
Spawn the process — use runChildProcess() for CLI-based agents or fetch() for HTTP-based agents
Parse output — convert the agent's stdout into structured data (session id, usage, summary, errors)
Handle session errors — if resume fails with "unknown session", retry with a fresh session and set clearSession: true
Return AdapterExecutionResult — populate all fields the agent runtime supports
Environment variables the server always injects:
Variable
Source
PAPERCLIP_AGENT_ID
agent.id
PAPERCLIP_COMPANY_ID
agent.companyId
PAPERCLIP_API_URL
Server's own URL
PAPERCLIP_RUN_ID
Current run id
PAPERCLIP_TASK_ID
context.taskId or context.issueId
PAPERCLIP_WAKE_REASON
context.wakeReason
PAPERCLIP_WAKE_COMMENT_ID
context.wakeCommentId or context.commentId
PAPERCLIP_APPROVAL_ID
context.approvalId
PAPERCLIP_APPROVAL_STATUS
context.approvalStatus
PAPERCLIP_LINKED_ISSUE_IDS
context.issueIds (comma-separated)
PAPERCLIP_API_KEY
authToken (if no explicit key in config)
server/parse.ts — Output Parser
Parse the agent's stdout format into structured data. Must handle:
Session identification — extract session/thread ID from init events
Unknown session detection — export an is<Agent>UnknownSessionError() function for retry logic
Treat agent output as untrusted. The stdout you're parsing comes from an LLM-driven process that may have executed arbitrary tool calls, fetched external content, or been influenced by prompt injection in the files it read. Parse defensively:
Never eval() or dynamically execute anything from output
Use safe extraction helpers (asString, asNumber, parseJson) — they return fallbacks on unexpected types
Validate session IDs and other structured data before passing them through
If output contains URLs, file paths, or commands, do not act on them in the adapter — just record them
server/index.ts — Server Exports
export { execute } from"./execute.js";
export { testEnvironment } from"./test.js";
export { parseMyAgentOutput, isMyAgentUnknownSessionError } from"./parse.js";
// Session codec — required for session persistenceexportconstsessionCodec: AdapterSessionCodec = {
deserialize(raw) { /* raw DB JSON -> typed params or null */ },
serialize(params) { /* typed params -> JSON for DB storage */ },
getDisplayId(params) { /* -> human-readable session id string */ },
};
server/test.ts — Environment Diagnostics
Implement adapter-specific preflight checks used by the UI test button.
Return check objects with deterministic code values
Map severity consistently (info / warn / error)
Compute final status:
fail if any error
warn if no errors and at least one warning
pass otherwise
This operation should be lightweight and side-effect free.
3.4 UI Module
ui/parse-stdout.ts — Transcript Parser
Converts individual stdout lines into TranscriptEntry[] for the run detail viewer. Must handle the agent's streaming output format and produce entries of these kinds:
Create ui/src/adapters/<name>/config-fields.tsx with a React component implementing AdapterConfigFieldsProps. This renders adapter-specific form fields in the agent creation/edit form.
Use the shared primitives from ui/src/components/agent-config-primitives:
Field — labeled form field wrapper
ToggleField — boolean toggle with label and hint
DraftInput — text input with draft/commit behavior
DraftNumberInput — number input with draft/commit behavior
help — standard hint text for common fields
The component must support both create mode (using values/set) and edit mode (using config/eff/mark).
3.5 CLI Module
cli/format-event.ts — Terminal Formatter
Pretty-prints stdout lines for paperclipai run --watch. Use picocolors for coloring.
import pc from"picocolors";
exportfunctionprintMyAgentStreamEvent(raw: string, debug: boolean): void {
// Parse JSON line from agent stdout// Print colored output: blue for system, green for assistant, yellow for tools// In debug mode, print unrecognized lines in gray
}
4. Registration Checklist
After creating the adapter package, register it in all three consumers:
4.1 Server Registry (server/src/adapters/registry.ts)
import { execute as myExecute, sessionCodec as mySessionCodec } from"@paperclipai/adapter-my-agent/server";
import { agentConfigurationDoc as myDoc, models as myModels } from"@paperclipai/adapter-my-agent";
constmyAgentAdapter: ServerAdapterModule = {
type: "my_agent",
execute: myExecute,
sessionCodec: mySessionCodec,
models: myModels,
supportsLocalAgentJwt: true, // true if agent can use Paperclip APIagentConfigurationDoc: myDoc,
};
// Add to the adaptersByType mapconst adaptersByType = newMap<string, ServerAdapterModule>(
[..., myAgentAdapter].map((a) => [a.type, a]),
);
import { printMyAgentStreamEvent } from"@paperclipai/adapter-my-agent/cli";
constmyAgentCLIAdapter: CLIAdapterModule = {
type: "my_agent",
formatStdoutEvent: printMyAgentStreamEvent,
};
// Add to the adaptersByType map
5. Session Management — Designing for Long Runs
Sessions allow agents to maintain conversation context across runs. The system is codec-based — each adapter defines how to serialize/deserialize its session state.
Design for long runs from the start. Treat session reuse as the default primitive, not an optimization to add later. An agent working on an issue may be woken dozens of times — for the initial assignment, approval callbacks, re-assignments, manual nudges. Each wake should resume the existing conversation so the agent retains full context about what it has already done, what files it has read, and what decisions it has made. Starting fresh each time wastes tokens on re-reading the same files and risks contradictory decisions.
Key concepts:
sessionParams is an opaque Record<string, unknown> stored in the DB per task
The adapter's sessionCodec.serialize() converts execution result data to storable params
sessionCodec.deserialize() converts stored params back for the next run
sessionCodec.getDisplayId() extracts a human-readable session ID for the UI
cwd-aware resume: if the session was created in a different cwd than the current config, skip resuming (prevents cross-project session contamination)
Unknown session retry: if resume fails with a "session not found" error, retry with a fresh session and return clearSession: true so Paperclip wipes the stale session
If the agent runtime supports any form of context compaction or conversation compression (e.g. Claude Code's automatic context management, or Codex's previous_response_id chaining), lean on it. Adapters that support session resume get compaction for free — the agent runtime handles context window management internally across resumes.
Never trust config values directly — always use asString, asNumber, etc.
Provide sensible defaults for every optional field
Document all fields in agentConfigurationDoc
Prompt Templates
Support promptTemplate for every run
Use renderTemplate() with the standard variable set
Default prompt should use DEFAULT_PAPERCLIP_AGENT_PROMPT_TEMPLATE from @paperclipai/adapter-utils/server-utils so local adapters share Paperclip's execution contract: act in the same heartbeat, avoid planning-only exits unless requested, leave durable progress and a next action, use child issues instead of polling, mark blockers with owner/action, and respect governance boundaries.
Error Handling
Differentiate timeout vs process error vs parse failure
Always populate errorMessage on failure
Include raw stdout/stderr in resultJson when parsing fails
Handle the agent CLI not being installed (command not found)
Logging
Call onLog("stdout", ...) and onLog("stderr", ...) for all process output — this feeds the real-time run viewer
Call onMeta(...) before spawning to record invocation details
Use redactEnvForLogs() when including env in meta
Paperclip Skills Injection
Paperclip ships shared skills (in the repo's top-level skills/ directory) that agents need at runtime — things like the paperclip API skill and the paperclip-create-agent workflow skill. Each adapter is responsible for making these skills discoverable by its agent runtime without polluting the agent's working directory.
The constraint: never copy or symlink skills into the agent's cwd. The cwd is the user's project checkout — writing .claude/skills/ or any other files into it would contaminate the repo with Paperclip internals, break git status, and potentially leak into commits.
The pattern: create a clean, isolated location for skills and tell the agent runtime to look there.
How claude-local does it:
At execution time, create a fresh tmpdir: mkdtemp("paperclip-skills-")
Inside it, create .claude/skills/ (the directory structure Claude Code expects)
Symlink each skill directory from the repo's skills/ into the tmpdir's .claude/skills/
Pass the tmpdir to Claude Code via --add-dir <tmpdir> — this makes Claude Code discover the skills as if they were registered in that directory, without touching the agent's actual cwd
Clean up the tmpdir in a finally block after the run completes
// From claude-local execute.tsasyncfunctionbuildSkillsDir(): Promise<string> {
const tmp = await fs.mkdtemp(path.join(os.tmpdir(), "paperclip-skills-"));
const target = path.join(tmp, ".claude", "skills");
await fs.mkdir(target, { recursive: true });
const entries = await fs.readdir(PAPERCLIP_SKILLS_DIR, { withFileTypes: true });
for (const entry of entries) {
if (entry.isDirectory()) {
await fs.symlink(
path.join(PAPERCLIP_SKILLS_DIR, entry.name),
path.join(target, entry.name),
);
}
}
return tmp;
}
// In execute(): pass --add-dir to Claude Codeconst skillsDir = awaitbuildSkillsDir();
args.push("--add-dir", skillsDir);
// ... run process ...// In finally: fs.rm(skillsDir, { recursive: true, force: true })
How codex-local does it:
Codex has a global personal skills directory ($CODEX_HOME/skills or ~/.codex/skills). The adapter symlinks Paperclip skills there if they don't already exist. This is acceptable because it's the agent tool's own config directory, not the user's project.
// From codex-local execute.tsasyncfunctionensureCodexSkillsInjected(onLog) {
const skillsHome = path.join(codexHomeDir(), "skills");
await fs.mkdir(skillsHome, { recursive: true });
for (const entry of entries) {
const target = path.join(skillsHome, entry.name);
const existing = await fs.lstat(target).catch(() =>null);
if (existing) continue; // Don't overwrite user's own skillsawait fs.symlink(source, target);
}
}
For a new adapter: figure out how your agent runtime discovers skills/plugins, then choose the cleanest injection path:
Best: tmpdir + flag (like claude-local) — if the runtime supports an "additional directory" flag, create a tmpdir, symlink skills in, pass the flag, clean up after. Zero side effects.
Acceptable: global config dir (like codex-local) — if the runtime has a global skills/plugins directory separate from the project, symlink there. Skip existing entries to avoid overwriting user customizations.
Acceptable: env var — if the runtime reads a skills/plugin path from an environment variable, point it at the repo's skills/ directory directly.
Last resort: prompt injection — if the runtime has no plugin system, include skill content in the prompt template itself. This uses tokens but avoids filesystem side effects entirely.
Skills as loaded procedures, not prompt bloat. The Paperclip skills (like paperclip and paperclip-create-agent) are designed as on-demand procedures: the agent sees skill metadata (name + description) in its context, but only loads the full SKILL.md content when it decides to invoke a skill. This keeps the base prompt small. When writing agentConfigurationDoc or prompt templates for your adapter, do not inline skill content — let the agent runtime's skill discovery do the work. The descriptions in each SKILL.md frontmatter act as routing logic: they tell the agent when to load the full skill, not what the skill contains.
Explicit vs. fuzzy skill invocation. For production workflows where reliability matters (e.g. an agent that must always call the Paperclip API to report status), use explicit instructions in the prompt template: "Use the paperclip skill to report your progress." Fuzzy routing (letting the model decide based on description matching) is fine for exploratory tasks but unreliable for mandatory procedures.
8. Security Considerations
Adapters sit at the boundary between Paperclip's orchestration layer and arbitrary agent execution. This is a high-risk surface.
Treat Agent Output as Untrusted
The agent process runs LLM-driven code that reads external files, fetches URLs, and executes tools. Its output may be influenced by prompt injection from the content it processes. The adapter's parse layer is a trust boundary — validate everything, execute nothing.
Secret Injection via Environment, Not Prompts
Never put secrets (API keys, tokens) into prompt templates or config fields that flow through the LLM. Instead, inject them as environment variables that the agent's tools can read directly:
PAPERCLIP_API_KEY is injected by the server into the process environment, not the prompt
User-provided secrets in config.env are passed as env vars, redacted in onMeta logs
The redactEnvForLogs() helper automatically masks any key matching /(key|token|secret|password|authorization|cookie)/i
This follows the "sidecar injection" pattern: the model never sees the real secret value, but the tools it invokes can read it from the environment.
Network Access
If your agent runtime supports network access controls (sandboxing, allowlists), configure them in the adapter:
Prefer minimal allowlists over open internet access. An agent that only needs to call the Paperclip API and GitHub should not have access to arbitrary hosts.
Skills + network = amplified risk. A skill that teaches the agent to make HTTP requests combined with unrestricted network access creates an exfiltration path. Constrain one or the other.
If the runtime supports layered policies (org-level defaults + per-request overrides), wire the org-level policy into the adapter config and let per-agent config narrow further.
Process Isolation
CLI-based adapters inherit the server's user permissions. The cwd and env config determine what the agent process can access on the filesystem.
dangerouslySkipPermissions / dangerouslyBypassApprovalsAndSandbox flags exist for development convenience but must be documented as dangerous in agentConfigurationDoc. Production deployments should not use them.
Timeout and grace period (timeoutSec, graceSec) are safety rails — always enforce them. A runaway agent process without a timeout can consume unbounded resources.
