profile

name	profile
description	Compiler profiling and hotspot analysis.
argument-hint	[fresh]
allowed-tools	Bash, Read, Grep, Glob, mcp__narsil-mcp__*
disable-model-invocation	true

./profile/ layout

./profile/all/ — all cases × prod/dev (just bench-flame-all):

• aggregate.top.txt — aggregated top across all cases
• <slug>_<mode>/top.txt — top of a single case
• <slug>_<mode>/profile.folded — folded stacks (can be up to 6 MB; do NOT read whole, only Grep by function name)
• <slug>_<mode>/profile.json, profile.json.syms.json — raw dumps, do NOT read whole; work through jq/grep surgically

./profile/one/ — a single case (just bench-flame <path> [--dev]):

• same artifacts as in <slug>_<mode>/ above

slug = path from tasks/benchmark/benches/compiler/ with / → _, without .svelte/.svelte.js. mode = prod | dev.

Step 1

If $ARGUMENTS == "fresh" — run just bench-flame-all. Tell the user the run takes ~4 min and start immediately, without asking for confirmation. After the run — read ./profile/all/aggregate.top.txt.

Otherwise — read the existing ./profile/all/aggregate.top.txt. If the file is missing — tell the user to run /profile fresh or just bench-flame-all manually and stop.

Step 2

Analyze ./profile/all/. Work through the top-5 hotspots from aggregate.top.txt — every one, not just the first. For each, find the driver-case: compare <slug>_<mode>/top.txt across subdirectories and pick where this function's self-% is highest.

Step 3

Report on the hotspots: what's hot, why, and what to do about it.

Later in the session

When the user picks an option — dig into the driver-case of that hotspot and propose concrete changes.

To profile a single case in isolation — just bench-flame <path> [--dev] (artifacts in ./profile/one/, see above).