Context Engineering Template is a repository of instructions, examples, workflows, and validation practices that give AI coding assistants the information they need to complete software tasks. It is for developers working with Claude Code or other coding assistants, and the catalogue entries package parts of its workflow as commands, agents, instructions, and a skill.
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.
git clone --depth 1 https://github.com/coleam00/context-engineering-introWrote 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.
[](https://agentmods.dev/commands/coleam00/context-engineering-intro/prime-isolation)<a href="https://agentmods.dev/commands/coleam00/context-engineering-intro/prime-isolation"><img src="https://agentmods.dev/badge/commands/coleam00/context-engineering-intro/prime-isolation/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/commands/coleam00/context-engineering-intro/prime-isolation"><img src="https://agentmods.dev/badge/commands/coleam00/context-engineering-intro/prime-isolation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00011 | $0.00895 |
| Opus 5.5 | $0.00004 | $0.00358 |
| Sonnet 5.5 | $0.00002 | $0.00179 |
| Haiku 4.5 | $0.00001 | $0.00089 |
Grade A, and why
prime-isolation 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 1mo 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.
This is a copy
100% identical to prime-isolation — 8 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
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.
Prime Isolation: Worktree Isolation and Git Ops Orientation
Objective
Orient on the isolation system (packages/isolation/) and low-level git operations
(packages/git/) before working on worktree lifecycle, branch management, or error handling.
Process
1. Understand the Package Structures
!ls packages/isolation/src/
!ls packages/git/src/
2. Understand Branded Git Types
Read packages/git/src/types.ts in full — branded types (RepoPath, BranchName,
WorktreePath) that prevent mix-ups between plain strings and typed git paths.
3. Understand Low-Level Git Operations
Read packages/git/src/worktree.ts first 60 lines — createWorktree, removeWorktree,
listWorktrees, worktreeExists, toWorktreePath (hashing strategy for unique paths).
Read packages/git/src/exec.ts — execFileAsync and mkdirAsync wrappers. Note:
always use execFileAsync (not exec) for git commands to avoid shell injection.
Read packages/git/src/branch.ts first 40 lines — checkout, getDefaultBranch,
isBranchMerged, findWorktreeByBranch.
4. Understand the Isolation Resolver
Read packages/isolation/src/resolver.ts first 130 lines — IsolationResolver class with
the 7-step resolution order:
- Existing environment reference (from conversation)
- No codebase → skip isolation
- Workflow reuse (same codebase + workflow identity)
- Linked issue sharing (cross-conversation)
- PR branch adoption (skill symbiosis)
- Limit check with auto-cleanup (default: 25 worktrees per codebase)
- Create new worktree
5. Understand Error Classification
Read packages/isolation/src/errors.ts in full — classifyIsolationError() maps raw git
errors (permission denied, no space left, timeout, not a git repo) to user-friendly messages.
IsolationBlockedError for limit-exceeded cases. isKnownIsolationError for detection.
6. Understand the Worktree Provider
Read packages/isolation/src/providers/worktree.ts first 60 lines — WorktreeProvider
implements IIsolationProvider: createEnvironment, removeEnvironment, environmentExists.
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.
- 1mo ago First seen · 106 lines · 11 tokens per session scan A 36f7d9777357
prime-isolation is a command published in the GitHub repository coleam00/context-engineering-intro (13,882 stars, last pushed 7mo ago), licensed MIT. It adds 11 tokens to every session and 895 once invoked, about $0.0000 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to prime-isolation, differing in 8 lines, and is treated as a copy.
Other commands, from other repositories
merge-conflict-analysis
You are analyzing merge conflicts for PR #${{ pr-number }}.
release-notes
Generate consistent, well-structured release notes from git history. Triggered on release tags following semver patterns (v..) to produce categorized changelog with breaking changes, features, fixes, and contributor attribution.
commit
A command that examines staged Git changes and proposes a commit message using the Conventional Commits format, such as feat, fix, or docs. Git is a tool for tracking changes to code.
repo-audit
Audit a codebase (local or remote GitHub/GitLab) against architecture principles and requirements, surfacing drift, risk, and missing decisions.
pr
Handle the full workflow from current branch state to an open, CI-monitored pull request.
codex-review
Use when asked to check, turn on, turn off, or switch this repo's Codex review mode (local, github, or off), or to report the effective mode and Codex sandbox status.