iOS Ettrace Performance

What it does

When your agent uses it

• Asked to profile an iOS app flow
• Gather simulator performance traces
• Identify CPU-heavy stacks
• Compare before/after traces

Example prompts

• “/ios-ettrace-performance”

Requirements

• Python 3
• A Bash shell

Workflow steps

7 steps, taken from the first numbered list in SKILL.md.

1. 1Pick one focused flow and write down the expected start and stop points.
2. 2Build the exact simulator app that will be installed and profiled.
3. 3Temporarily link ETTrace into that app target for simulator/debug profiling.
4. 4Collect UUID-matched dSYMs for the app executable and embedded dynamic frameworks.
5. 5Capture one launch or runtime trace.
6. 6Preserve the processed flamegraph JSON immediately after the run.
7. 7Analyze only the processed JSON and report the flow, artifacts, hotspots, and caveats.

What it can do on your machine

Read from SKILL.md and the folder at commit da69700. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Ships 2 files in scripts/ (Python and Shell), which the agent can run.

  Shell commands in SKILL.md call:

  • xcodebuild
  • brew
  • git
  • python3

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Hosts in commands or code, which the agent is likely to contact:

  • github.com

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

iOS Ettrace Performance loads about 2.3k tokens when it runs. Until then it costs about 97 tokens; SKILL.md has 787 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~97

When it runs · the whole SKILL.md, loaded when a task matches

~2.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from omarshahine/HomeClaw at commit da69700, republished under its MIT licence (© omarshahine). 787 words, ~2,262 tokens.

name

ios-ettrace-performance

description

Capture and interpret ETTrace profiles for iOS simulator apps, including symbolicated launch and runtime flamegraphs. Use when asked to profile an iOS app flow, gather simulator performance traces, identify CPU-heavy stacks, compare before/after traces, or produce flamegraph evidence for startup, scrolling, navigation, rendering, or other user-visible latency.

if [ -z "${RUN_DIR:-}" ]; then
  RUN_DIR="$(mktemp -d "${TMPDIR:-/tmp}/codex-ios-ettrace.XXXXXX")"
fi
mkdir -p "$RUN_DIR"

brew install emergetools/homebrew-tap/ettrace

ETTRACE_TAG="${ETTRACE_TAG:-v1.1.0}" # Override to match the installed runner when Homebrew updates.
ETTRACE_SRC="$RUN_DIR/ETTrace-src"
if [ ! -d "$ETTRACE_SRC" ]; then
  git clone --depth 1 --branch "$ETTRACE_TAG" https://github.com/EmergeTools/ETTrace "$ETTRACE_SRC"
fi

rm -rf "$RUN_DIR/ETTrace-iphonesimulator.xcarchive" "$RUN_DIR/ETTrace.xcframework"
pushd "$ETTRACE_SRC" >/dev/null
xcodebuild archive \
  -scheme ETTrace \
  -archivePath "$RUN_DIR/ETTrace-iphonesimulator.xcarchive" \
  -sdk iphonesimulator \
  -destination 'generic/platform=iOS Simulator' \
  BUILD_LIBRARY_FOR_DISTRIBUTION=YES \
  INSTALL_PATH='Library/Frameworks' \
  SKIP_INSTALL=NO \
  CLANG_CXX_LANGUAGE_STANDARD=c++17

xcodebuild -create-xcframework \
  -framework "$RUN_DIR/ETTrace-iphonesimulator.xcarchive/Products/Library/Frameworks/ETTrace.framework" \
  -output "$RUN_DIR/ETTrace.xcframework"
popd >/dev/null

load("@rules_apple//apple:apple.bzl", "apple_dynamic_xcframework_import")

package(default_visibility = ["//visibility:public"])

apple_dynamic_xcframework_import(
    name = "ETTrace",
    xcframework_imports = glob(["ETTrace.xcframework/**"]),
)

SKILL_DIR="<absolute path to this loaded skill folder>"
APP="<path-to-built-simulator-App.app>"
DSYMS="$RUN_DIR/dsyms"

"$SKILL_DIR/scripts/collect_ios_dsyms.sh" \
  --app "$APP" \
  --out-dir "$DSYMS" \
  --search-root "$(dirname "$APP")" \
  --search-root "$PWD" \
  --extra-dsym "$RUN_DIR/ETTrace-iphonesimulator.xcarchive/dSYMs/ETTrace.framework.dSYM"

dwarfdump --uuid "$APP/$(/usr/libexec/PlistBuddy -c 'Print :CFBundleExecutable' "$APP/Info.plist")"
find "$DSYMS" -maxdepth 1 -type d -name '*.dSYM' -print -exec dwarfdump --uuid {} \;

cd "$RUN_DIR"
CAPTURE_MARKER="$RUN_DIR/.ettrace-capture-start"
: > "$CAPTURE_MARKER"
find "$RUN_DIR" -maxdepth 1 \( -name 'output.json' -o -name 'output_*.json' \) -delete
ettrace --simulator --launch --verbose --dsyms "$DSYMS"

cd "$RUN_DIR"
CAPTURE_MARKER="$RUN_DIR/.ettrace-capture-start"
: > "$CAPTURE_MARKER"
find "$RUN_DIR" -maxdepth 1 \( -name 'output.json' -o -name 'output_*.json' \) -delete
ettrace --simulator --verbose --dsyms "$DSYMS"

PRESERVED_DIR="$(mktemp -d "$RUN_DIR/run-$(date +%Y%m%d-%H%M%S).XXXXXX")"
: > "$PRESERVED_DIR/summary.txt"
if [ ! -e "$CAPTURE_MARKER" ]; then
  echo "error: capture marker missing; start a fresh ETTrace capture before preserving outputs" >&2
  exit 1
fi
find "$RUN_DIR" -maxdepth 1 -name 'output_*.json' -newer "$CAPTURE_MARKER" -print | while IFS= read -r json; do
  preserved="$PRESERVED_DIR/${json##*/}"
  cp "$json" "$preserved"
  {
    echo "## ${preserved##*/}"
    python3 "$SKILL_DIR/scripts/analyze_flamegraph_json.py" "$preserved"
  } >> "$PRESERVED_DIR/summary.txt"
done
if [ ! -s "$PRESERVED_DIR/summary.txt" ]; then
  echo "error: no fresh processed ETTrace output JSON found in $RUN_DIR" >&2
  exit 1
fi

© omarshahine, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 3 other files (scripts) in .claude/skills/ios-ettrace-performance of omarshahine/HomeClaw.

• SKILL.md
• agents/openai.yaml
• scripts/analyze_flamegraph_json.py
• scripts/collect_ios_dsyms.sh

Open the folder on GitHubat commit da69700

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in omarshahine/HomeClaw, which our catalogue first saw on October 7, 2026.

• AstraFoundry/KumoApp.agents/skills/ios-ettrace-performance