alive:build-extensions

alive:build-extensions is a skill for Claude Code, Codex from alivecontext/alive. It costs 60 tokens per session (1,486 once invoked), scanned A, original, MIT.

A workflow for creating new skills, rules, or hooks for an ALIVE workspace. Skills describe repeatable processes, rules guide behaviour, and hooks run automatically when specified events occur.

In plain words
What is it for?
Use it to create custom workflows, enforce behavioural rules, automate actions on events such as saves, or package related capabilities for distribution.
Why use it?
It lets you turn repeated manual work or project constraints into reusable agent capabilities. It also checks compatibility and validates the result.

Skill for Claude CodeCodex

Part of the alive plugin — 17 skills, 5 hooks 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 skills/alivecontext/alive/build-extensions
Any agent
npx skills add alivecontext/alive --skill build-extensions
Clone the repo
git clone --depth 1 https://github.com/alivecontext/alive

Made for: Claude Code, Codex.

Or install alive, the plugin that ships this one along with the rest of its 17 skills, 5 hooks.

Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,486 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 $0.00060 $0.01486
Opus 5 $0.00030 $0.00743
Sonnet 5 $0.00012 $0.00297
Haiku 4.5 $0.00006 $0.00149

Measured 3d ago against content hash 21dd3ed8d247, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

alive:build-extensions 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 3d 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/alive/skills/build-extensions/SKILL.md · 204 lines

How it starts

The opening of the file, as written. The whole thing — 204 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Extend

Build custom capabilities that integrate cleanly with the ALIVE Context System.

Not about adjusting preferences or voice (that's alive:settings). Extend is about creating NEW things — skills, rules, hooks — that make the system do something it couldn't before.


What It Builds

Type What it is Where it lives
Skill Repeatable workflow with instructions .alive/skills/{skill-name}/SKILL.md
Rule Behavioral constraint or guide .alive/rules/{rule-name}.md
Hook Automated trigger on system events .alive/hooks/ (scripts + hooks.json)
Plugin Distributable package of skills + rules + hooks Hands off to contributor@alivecontext

Flow

1. Understand What the Human Wants

"I want to automatically tag emails by walnut" "Every time I save, it should update my project board" "I keep doing this manually every session — can we automate it?"

The squirrel determines: is this a skill (process), a rule (constraint), a hook (automation), or a combination?

╭─ squirrel that sounds like a hook — an automated trigger that fires on save.
│  Want me to build it?
│
│  It would:
│  - Fire after every alive:save
│  - Read the routed stash items
│  - Update your project board via API
│
│  > Build it / Tell me more / Not now
╰─

2. Check Compatibility

Before writing anything:

  • Read the current plugin version from plugin.json
  • Check which hook events are available (SessionStart, PreToolUse, PostToolUse, PreCompact, UserPromptSubmit)
  • Verify the name doesn't collide with existing skills, rules, or hooks
  • Check for rule contradictions with existing rules

3. Write to the Human's Space

NEVER write to the plugin cache. Plugin cache (~/.claude/plugins/) gets overwritten on update. Custom capabilities live in the human's own space:

  • Custom skills: $WORLD_ROOT/.alive/skills/{skill-name}/SKILL.md
  • Custom rules: $WORLD_ROOT/.alive/rules/{rule-name}.md
  • Custom hooks: $WORLD_ROOT/.alive/hooks/ (scripts + .claude/hooks.json additions)

Read the full file on GitHub · 204 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. 3d ago First seen · 204 lines · 60 tokens per session scan A 21dd3ed8d247

Subscribe to this mod's changes

alive:build-extensions is a skill published in the GitHub repository alivecontext/alive (127 stars, last pushed 8d ago), licensed MIT. It adds 60 tokens to every session and 1,486 once invoked, about $0.0003 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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