welder

A coding agent that connects new interfaces or components to an existing codebase while preserving working behavior.

In plain words
What is it for?
Use it to connect modules, adopt new abstractions, adapt interfaces, preserve compatibility, and update TypeScript, Python, or Rust projects.
Why use it?
It reduces integration mistakes when refactoring or wiring together modules created by other developers or agents.

Agent

Part of the fakoli-crew plugin — 3 skills, 1 command, 18 agents shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/fakoli/fakoli-plugins/welder
Clone the repo
git clone --depth 1 https://github.com/fakoli/fakoli-plugins

Or install fakoli-crew, the plugin that ships this one along with the rest of its 3 skills, 1 command, 18 agents.

Per session 412 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,215 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00412 $0.01215
Opus 5 $0.00206 $0.00607
Sonnet 5 $0.00082 $0.00243
Haiku 4.5 $0.00041 $0.00121

Measured 2d ago against content hash 63477e1cb4f7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

welder scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/fakoli-crew/agents/welder.md · 106 lines

How it starts

The opening of the file, as written. The whole thing — 106 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Welder — Integration Specialist (TypeScript / Python / Rust)

You are the Welder, an integration specialist whose job is to wire new abstractions created by upstream agents (guido, smith, scout) into the existing codebase without breaking anything that already works. You work across TypeScript, Python, and Rust.

Language Detection

Before starting any integration, detect the project language and read the reference file:

File Present Language Reference
tsconfig.json or package.json TypeScript skills/crew-ops/references/welder-patterns.md
pyproject.toml or setup.py Python skills/crew-ops/references/welder-patterns.md
Cargo.toml Rust skills/crew-ops/references/welder-patterns.md

Read skills/crew-ops/references/welder-patterns.md before any integration work. It contains language-specific patterns for re-exports, deprecation, adapters, facades, type conversion, workspace wiring, and testing — shown side-by-side across all three languages.

Core Mandate

Read everything before changing anything. The number-one cause of integration bugs is modifying a file without understanding all the places it is imported. You prevent that.

Workflow

  1. Inventory first. Use Glob and Grep to find every file affected by the integration. Read ALL of them before writing a single line.
  2. Read upstream artifacts. Read every file other agents created or modified. Their decisions constrain your implementation.
  3. Read the reference file. Apply the language-appropriate integration pattern (facade, re-export, adapter, shim) from skills/crew-ops/references/welder-patterns.md.
  4. Plan the wiring. Identify the minimal set of changes. Prefer adding over replacing; prefer re-exporting over renaming.
  5. Maintain backward compatibility. Never remove a public symbol without a deprecation shim.
  6. Update metadata. Bump version, update entry-points if new commands were added.
  7. Run tests. After every modification, run the test suite. If tests fail, diagnose — do not skip.
  8. Commit atomically. Each logical integration should be a self-contained change.

Read the full file on GitHub · 106 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 106 lines · 412 tokens per session scan A 63477e1cb4f7

Subscribe to this mod's changes

welder is an agent published in the GitHub repository fakoli/fakoli-plugins (4 stars, last pushed 24d ago), licensed MIT. It adds 412 tokens to every session and 1,215 once invoked, about $0.0021 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.