worktree-isolation

worktree-isolation is a cursor rule for coding agents from robertsfeir/atelier-pipeline. It costs 1,189 tokens per session, scanned A, original, Apache-2.0.

A set of rules for giving each coding session its own Git worktree, which is a separate working directory linked to a repository branch.

In plain words
What is it for?
Use it when pipeline sessions need isolated workspaces or when Agent Teams branches tasks across separate Git worktrees.
Why use it?
It keeps simultaneous agent sessions from changing the same files or interfering with one another. It also defines how sessions are created, branched, and cleaned up.

Cursor rule

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 rules/robertsfeir/atelier-pipeline/worktree-isolation
Clone the repo
git clone --depth 1 https://github.com/robertsfeir/atelier-pipeline

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 worktree-isolation

README.md
[![agentmods](https://agentmods.dev/badge/rules/robertsfeir/atelier-pipeline/worktree-isolation.svg)](https://agentmods.dev/rules/robertsfeir/atelier-pipeline/worktree-isolation)
Your own site
<a href="https://agentmods.dev/rules/robertsfeir/atelier-pipeline/worktree-isolation"><img src="https://agentmods.dev/badge/rules/robertsfeir/atelier-pipeline/worktree-isolation.svg" alt="Measured on agentmods" height="20"></a>
Per session 1,189 This file is loaded in full into every session.
When invoked 1,189 The same file — it is already loaded in full.
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 $0.01189 $0.01189
Opus 5 $0.00594 $0.00594
Sonnet 5 $0.00238 $0.00238
Haiku 4.5 $0.00119 $0.00119

Measured 5d ago against content hash 0c8203e3d9c9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

worktree-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 5d 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.

.cursor-plugin/rules/worktree-isolation.mdc · 124 lines

How it starts

The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Worktree-Per-Session Isolation

JIT-loaded reference. Extracted from pipeline-orchestration.md. Eva loads this file on demand when a pipeline session needs worktree creation, cleanup, or Agent-Teams branching details. The <protocol id="worktree-per-session"> anchor is preserved for downstream references.

Worktree-Per-Session Isolation (ADR-0038)

Every pipeline session gets a dedicated git worktree, regardless of sizing. Eva creates the worktree at pipeline start, before any Colby invocation.

Creation Sequence

After sizing decision and branch name determination, Eva runs:

# 1. Generate session ID (8 hex chars)
SESSION_ID=$(openssl rand -hex 4)

# 2. Determine branch name
# Micro/Small:   session/<session-id>
# Medium/Large:  feature/<adr-slug>-<session-id>
BRANCH_NAME="session/${SESSION_ID}"  # or feature/<slug>-${SESSION_ID}

# 3. Determine worktree path (sibling directory, NOT inside repo)
PROJECT_SLUG=$(basename "$(git remote get-url origin 2>/dev/null)" .git 2>/dev/null || basename "$PWD")
WORKTREE_PATH="../${PROJECT_SLUG}-${SESSION_ID}"

# 4. Create worktree with new branch
git worktree add -b "$BRANCH_NAME" "$WORKTREE_PATH"

# 5. Copy gitignored config (brain-config.json)
if [ -f ".claude/brain-config.json" ]; then
  cp ".claude/brain-config.json" "${WORKTREE_PATH}/.claude/brain-config.json"
fi

Branch naming table:

Pipeline Sizing Branch Prefix Merge Strategy
Micro session/<8-hex> Fast-forward to main
Small session/<8-hex> Fast-forward to main
Medium feature/<adr-slug>-<8-hex> MR/PR flow
Large feature/<adr-slug>-<8-hex> MR/PR flow

Worktree creation is not conditional — Micro and Small sessions create session branches and dedicated worktrees exactly as Medium and Large do.

Failure Handling

If git worktree add fails (branch name conflict, disk full, permissions), Eva announces the error verbatim and does NOT proceed to Colby. The pipeline is a blocker. The user resolves the issue (delete stale worktree, choose different branch name) and retries. No silent fallback to in-place operation.

Read the full file on GitHub · 124 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. 5d ago First seen · 124 lines · 1,189 tokens per session scan A 0c8203e3d9c9

Subscribe to this mod's changes

worktree-isolation is a cursor rule published in the GitHub repository robertsfeir/atelier-pipeline (25 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 1,189 tokens to every session, about $0.0059 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.