forge-app-builder

forge-app-builder is a skill for Claude Code, Codex from atlassian/forge-skills. It costs 91 tokens per session (1,436 once invoked), scanned A, original, Apache-2.0.

A guide for planning, building and safely extending Atlassian Forge apps, which are apps that add features to Atlassian products.

In plain words
What is it for?
Use it to create or modify Forge apps, including manifests, user interfaces, backend functions, events, storage, permissions and API integrations.
Why use it?
It keeps app work aligned with current official Forge documentation and emphasizes checking permissions, manifests and existing projects before changes.

Skill for Claude CodeCodex ✓ vendor

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also agents/openai.yaml present.

Part of the forge-skills plugin — 6 skills, 2 MCP servers shipped together

Good fit Use it to create or modify Forge apps, including manifests, user interfaces…

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/atlassian/forge-skills/forge-app-builder
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.

Any agent
npx skills add atlassian/forge-skills --skill forge-app-builder
Clone the repo
git clone --depth 1 https://github.com/atlassian/forge-skills

Made for: Claude Code, Codex.

Or install forge-skills, the plugin that ships this one along with the rest of its 6 skills, 2 MCP servers.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for forge-app-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/atlassian/forge-skills/forge-app-builder.svg)](https://agentmods.dev/skills/atlassian/forge-skills/forge-app-builder)
Your own site
<a href="https://agentmods.dev/skills/atlassian/forge-skills/forge-app-builder"><img src="https://agentmods.dev/badge/skills/atlassian/forge-skills/forge-app-builder.svg" alt="Measured on agentmods" height="20"></a>
Per session 91 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,436 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00091 $0.01436
Opus 5 $0.00046 $0.00718
Sonnet 5 $0.00018 $0.00287
Haiku 4.5 $0.00009 $0.00144

Measured 7d ago against content hash 3cac8fd0028e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

forge-app-builder 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 7d ago.

The scan reads SKILL.md. This mod also ships 11 executable files (evals/fixtures/existing-ui-kit-app/src/index.js, scripts/__init__.py, scripts/create_forge_app.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/forge-app-builder/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Forge App Builder

Route each request through only the branches and capability gates it needs. Keep platform facts live and keep local guidance focused on safe decisions.

Preserve these invariants

  1. Retrieve current official Forge guidance before committing to platform syntax, modules, APIs, scopes, limits, runtimes, packages, lifecycle status, or CLI flags.
  2. Register every new deployable app with forge create; never hand-build an app identity or replace a failed creation with an unregistered scaffold.
  3. Inspect an existing app and its repository instructions before planning or editing it. Preserve unrelated user changes.
  4. Never request or accept credentials in chat. Use the relevant interactive CLI or secure configuration flow.
  5. Never accept Forge terms or billing consent, deploy, install, upgrade, promote, set a production variable, or change a live site without explicit authorization and a confirmed target.
  6. Validate every manifest change against the exact current reference and with forge lint.
  7. Use least privilege and avoid unnecessary egress, privileged backend operations, and migrations.
  8. Prefix Forge CLI commands run for this skill with ATL_FORGE_ATTRIBUTION_SKILL_NAME=forge-app-builder; exclude user-run forge login and forge tunnel.

Route the primary intent

Choose one primary route before loading implementation guidance:

Intent Route
Architecture, feasibility, or implementation plan only Read references/plan-only.md; stop before mutations
Create a deployable app Read references/create-new-app.md
Add or change behavior in an existing app Read references/extend-existing-app.md
Known error, failed command, blank UI, logs, or unexpected behavior Route to forge-debugger
Broad pre-deploy or release-readiness review Route to forge-app-review
Deep security review or static analysis Route to forge-security-review
Cost or platform-consumption optimization Route to forge-cost-optimizer
Teamwork Graph connector Route to forge-connector

Read the full file on GitHub · 80 lines

Files

What ships with it

33 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 80 lines · 91 tokens per session scan A 3cac8fd0028e

Subscribe to this mod's changes

forge-app-builder is a skill published in the GitHub repository atlassian/forge-skills (21 stars, last pushed yesterday), licensed Apache-2.0. It adds 91 tokens to every session and 1,436 once invoked, about $0.0005 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 2026-08-30.

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