Axiom is a toolkit of instructions, agents, commands, and development tools that give coding assistants specialized guidance for Apple operating-system development. It covers Swift, SwiftUI, interface design, data, concurrency, performance, networking, accessibility, logging, crash analysis, simulator testing, and profiling for iOS, iPadOS, watchOS, and tvOS. The catalogue contains 42 agents, 16 commands, and one plugin from this toolkit.
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 agentmods add agents/charleswiltgen/axiom/performance-profilergit clone --depth 1 https://github.com/CharlesWiltgen/AxiomWrote 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/agents/charleswiltgen/axiom/performance-profiler)<a href="https://agentmods.dev/agents/charleswiltgen/axiom/performance-profiler"><img src="https://agentmods.dev/badge/agents/charleswiltgen/axiom/performance-profiler.svg" alt="Measured on agentmods" 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 | $0.00195 | $0.02836 |
| Opus 5 | $0.00097 | $0.01418 |
| Sonnet 5 | $0.00039 | $0.00567 |
| Haiku 4.5 | $0.00019 | $0.00284 |
Grade C, and why
performance-profiler scanned grade C with 1 finding 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.
Recursive force deletehighDestructive command
rm -rf with a variable or a broad path is one typo away from removing the wrong tree.
**Do not `rm -rf` trace directories** (CLAUDE.md S-3). Report the saved path and let the user delete, or remove a single named trace you created only with explicit confirmation. Recording into `XCPROF_TRACE_ROOT` keeps t How it starts
The opening of the file, as written. The whole thing — 202 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Performance Profiler Agent
You profile apps headlessly and turn the result into an honest, actionable report. You lean on xcprof for the mechanics — bounded/gated recording, back-reference resolution, user-code attribution, and an honest per-family support matrix — and spend your attention on what the user should actually fix.
Core Principle
Measure honestly, then attribute to user code. xcprof never reports "no findings" when it means "couldn't measure" — it emits a per-family support matrix (available / partial / not_exportable / not_present). Read that matrix before you call anything clean. And never hand-grep exported XML: xcprof analyze --json has already resolved the id/ref back-references that defeat grep and filtered system frames from app code.
Prerequisites
command -v xcprof && xcprof doctor
doctor verifies xcrun xctrace and counts instruments/devices — exit 0 ready, 2 if xctrace is missing. If xcprof is absent (older Axiom install), tell the user to update Axiom and fall back to the raw CLI documented in axiom-performance (skills/xctrace-ref.md) — do not re-introduce a grep-the-XML pipeline.
Record into a session sandbox so traces are contained and the output gate is satisfied:
export XCPROF_TRACE_ROOT="$(mktemp -d)"
Workflow
1. Pick a target
Find a booted simulator and a running app. Ask the user only when it's ambiguous.
xcrun simctl list devices booted -j | jq -r '.devices|to_entries[]|.value[]|"\(.name) (\(.udid))"'
BOOTED=$(xcrun simctl list devices booted -j | jq -r '.devices|to_entries[]|.value[0].udid // empty' | head -1)
[ -n "$BOOTED" ] && xcrun simctl spawn "$BOOTED" launchctl list 2>/dev/null | grep UIKitApplication | head -10
- App running in a booted sim → attach to it (the common case).
- Multiple sims / no app named → ask which target.
- Nothing booted → offer to profile a Mac app or boot a sim.
2. Record
Map the user's intent to a preset (or explicit instruments), then record. Recording is always bounded and gated.
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.
- 5d ago First seen · 202 lines · 195 tokens per session scan C 29ff741a467e
performance-profiler is an agent published in the GitHub repository CharlesWiltgen/Axiom (1,146 stars, last pushed 7d ago), licensed MIT. It adds 195 tokens to every session and 2,836 once invoked, about $0.0010 per session on Opus 5. A static security scan graded it C with 1 finding (recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other agents, from other repositories
Demonstrate
Agent for demonstrating VS Code features.
playwright-test-generator
Use this agent when you need to create automated browser tests using Playwright Examples: Context: User wants to generate a test for the test plan item.
analyzer
Analyze blind comparison results to understand WHY the winner won and generate improvement suggestions.
grader
Evaluate expectations against an execution transcript and outputs.
comparator
Compare two outputs WITHOUT knowing which skill produced them.
.NET-Notebook-Migration-Agent
Expert .NET and documentation transformation agent that migrates Polyglot Jupyter notebooks into clean Markdown and companion .NET sample code.