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.
npx skills add arittr/spectacular --skill understanding-cross-phase-stackinggit clone --depth 1 https://github.com/arittr/spectacularWrote 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/skills/arittr/spectacular/understanding-cross-phase-stacking)<a href="https://agentmods.dev/skills/arittr/spectacular/understanding-cross-phase-stacking"><img src="https://agentmods.dev/badge/skills/arittr/spectacular/understanding-cross-phase-stacking/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/skills/arittr/spectacular/understanding-cross-phase-stacking"><img src="https://agentmods.dev/badge/skills/arittr/spectacular/understanding-cross-phase-stacking.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 | $0.00046 | $0.01733 |
| Opus 5 | $0.00023 | $0.00866 |
| Sonnet 5 | $0.00009 | $0.00347 |
| Haiku 4.5 | $0.00005 | $0.00173 |
Grade A, and why
understanding-cross-phase-stacking 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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 218 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Understanding Cross-Phase Stacking
Overview
Phases automatically build on each other's completed work. Understanding how phases chain together is essential for correct execution.
This is a reference skill - read it to understand cross-phase dependencies, not to execute a workflow.
When to Use
Use this skill when:
- Starting a new phase (need to understand what base to build from)
- Debugging stack relationships across phase boundaries
- Verifying phases are chaining correctly
- Understanding why parallel worktrees use specific base branches
Mental model check: If you're thinking "create worktrees from {runid}-main branch", you need this skill.
The Cross-Phase Inheritance Principle
MAIN WORKTREE CURRENT BRANCH = LATEST COMPLETED WORK
Key insight:
- Sequential phases leave main worktree on their last task's branch
- Parallel phases leave main worktree on their last stacked branch
- Next phase (sequential or parallel) inherits from current branch, not original base
This creates automatic linear chaining across all phases.
Example: Sequential → Parallel → Sequential
Phase 1 (Sequential) - Database Setup
# Working in: .worktrees/{runid}-main
# Starting from: {runid}-main (base branch)
# Task 1: Database schema
gs branch create {runid}-task-1-1-database-schema
# Creates branch, commits work
# Main worktree now on: {runid}-task-1-1-database-schema ← KEY STATE
Phase 1 result:
- Branch created:
{runid}-task-1-1-database-schema - Main worktree current branch:
{runid}-task-1-1-database-schema - This branch becomes Phase 2's base
Phase 2 (Parallel) - Three Feature Implementations
# Base detection (CRITICAL):
BASE_BRANCH=$(git -C .worktrees/{runid}-main branch --show-current)
# Returns: {runid}-task-1-1-database-schema ← Inherits from Phase 1
# Create parallel worktrees FROM Phase 1's completed branch
git worktree add .worktrees/{runid}-task-2-1 --detach "$BASE_BRANCH"
git worktree add .worktrees/{runid}-task-2-2 --detach "$BASE_BRANCH"
git worktree add .worktrees/{runid}-task-2-3 --detach "$BASE_BRANCH"
# All 3 parallel tasks build on Phase 1's database schema
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.
- 9d ago First seen · 218 lines · 46 tokens per session scan A 057348a6a247
understanding-cross-phase-stacking is a skill published in the GitHub repository arittr/spectacular (20 stars, last pushed 7mo ago), licensed MIT. It adds 46 tokens to every session and 1,733 once invoked, about $0.0002 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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