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Trace the transitive import weight of any TypeScript or Python entry point. Point it at a file, get back what gets pulled in at startup and how much code it costs.
Only static imports count toward the weight. Dynamic import() and type-only imports are tracked separately.
cargo install chainsaw-cli
Requires Rust 1.91+.
Works the same way. Resolution matches importlib behavior -- source roots, virtualenv, .pth files, sys.path modifications, C extensions.
$ chainsaw trace app/main.py
app/main.py
Static transitive weight: 2.1 MB (608 modules)
Heavy dependencies (static):
botocore 1.2 MB 340 files
-> app/main.py -> ... -> boto3 -> botocore
$ chainsaw trace src/index.ts --chain zod 3 chains to "zod" (3 hops): 1. src/index.ts -> src/api/routes.ts -> src/api/validation.ts -> zod 2. src/index.ts -> src/api/middleware.ts -> src/api/validation.ts -> zod 3. src/index.ts -> src/config/env.ts -> src/api/validation.ts -> zod
All three chains pass through src/api/validation.ts. Chainsaw finds that:
$ chainsaw trace src/index.ts --cut zod 1 cut point to sever all 3 chains to "zod": src/api/validation.ts (breaks 3/3 chains)
Make that import dynamic and zod drops out of your startup path.
When no single file can break all chains:
No single cut point can sever all 3 chains to "chalk". Each chain takes a different path — multiple fixes needed.
Compare two entry points:
$ chainsaw trace src/index.ts --diff src/worker.ts Diff: src/index.ts vs src/worker.ts src/index.ts 8.2 MB src/worker.ts 2.4 MB Delta -5.8 MB Only in src/index.ts: - undici 1.1 MB - date-fns 619 KB - zod 537 KB Only in src/worker.ts: + html-rewriter 84 KB Shared: 12 packages
Or save a snapshot and compare before/after:
$ chainsaw trace src/index.ts --save before.json # ... make changes ... $ chainsaw trace src/index.ts --diff-from before.json
The diff subcommand compares two saved snapshots directly: chainsaw diff before.json after.json
Compare against a git ref to see how weight changed over time:
$ chainsaw diff HEAD~10 --entry src/index.ts
In a monorepo, the diff target can be in a different package -- chainsaw builds a separate graph from that package's root automatically.
Run multiple queries against a cached graph without rebuilding:
$ chainsaw repl src/index.ts chainsaw> trace chainsaw> chain zod chainsaw> cut zod chainsaw> packages
$ chainsaw trace src/index.ts --max-weight 5MB --quiet --top 0 --top-modules 0 error: static transitive weight 8.2 MB (2140 modules) exceeds --max-weight threshold 5.0 MB
Exits non-zero when static weight exceeds the threshold. Accepts 5MB, 500KB, 100B.
$ chainsaw trace src/index.ts --json --quiet | jq .static_weight_bytes
chainsaw completions zsh > ~/.zfunc/_chainsaw chainsaw completions bash > /etc/bash_completion.d/chainsaw chainsaw completions fish > ~/.config/fish/completions/chainsaw.fish
Run chainsaw --help for the full flag reference.
git clone https://github.com/rocketman-code/chainsaw.git cd chainsaw cargo xtask install-hooks cargo test --workspace
See CONTRIBUTING.md for the full development guide.
GPLv3. See LICENSE.