nahid-sparktales / stack-detection
Establish what a frontend project actually uses — framework, router, package manager, styling, component layer, TypeScript posture — from package.json, lockfiles, config files and the source itself, before loading framework-specific guidance or writing a line of code. Fires at the start of any frontend task in an unfamiliar or half-remembered repo, and whenever you are about to assume a convention. Not for choosing a stack for a new project, and not a substitute for reading the code you are about to change.
Stack detection
Most wrong frontend edits are correct code for a stack the project does not use. Detection is
cheap; guessing is not.
When this fires
Before the first edit in a frontend repo you have not already mapped in this session, and again
whenever you catch yourself about to say "this project probably uses". It does not fire for a repo
whose conventions you have already read this session.
Procedure
Find the right
package.jsonfirst. In a monorepo the root one describes the workspace,
not the app. Locate the nearestpackage.jsonabove the file you are changing, and note
whether a root one also exists — dependencies can be hoisted, tooling config usually is.Read dependencies and scripts together.
dependenciesanddevDependenciessay what is
installed;scriptssay what is actually run. The dev, build and test commands are the ones to
use later — do not inventnpm run devif the project spells it differently.Get real versions from the lockfile, not the range.
^15.0.0inpackage.jsonis a
constraint. The lockfile (package-lock.json,pnpm-lock.yaml,yarn.lock,bun.lock*) holds
the resolved version, and its filename is also the only reliable statement of which package
manager to invoke. Two lockfiles present is a finding, not a choice.Read the config files that exist, and note the ones that do not. Build/framework config,
TypeScript config, lint and format config, test config. Their presence tells you the tool is
wired in; their contents tell you path aliases, strictness, and what is excluded.Confirm the routing and rendering model from the directory layout, not from the framework
name. Which route directories exist, where the entry file is, whether routes are file-based or
declared in code, and — for frameworks with a server/client split — which files carry the
directives that mark the boundary.Identify the styling layer and its version. A config file's existence does not pin a major
version; check the lockfile and how the stylesheet imports the framework. Also check for a CSS
modules / styled-in-JS / vanilla CSS layer coexisting with it — mixed styling is common and
changes what you should write.Check for a vendored component layer.
components.jsonor an equivalent marker plus a UI
directory means components were copied in and are now project source (seeshadcn-ui).Open two or three real source files in the area you will touch. Config says what is
possible; the source says what this team actually does — import style, file naming, test
colocation, state library usage.**Write the stack down in one short block, with the file each claim came from, and a separate
list of what you could not determine.** That list is part of the result.
What a signal does and does not license
A framework in
dependencies→ the framework is installed. It does not tell you which
router, rendering mode or directory convention is in use. Read the layout.A config file exists → that tool runs. It does not tell you the major version, and majors
move config between files. The lockfile decides.TypeScript installed → files are typed. It does not mean
strictis on, thatanyis
discouraged, or that generated types are current. Readtsconfigand one real file.A test framework installed → tests can run. It does not mean they pass, cover this area, or
are run in CI. Running them is a separate act.A state or data library installed → it is available somewhere. It does not mean the module
you are editing uses it. Grep the directory you are in.components.jsonpresent → a component CLI was used at some point. It does not mean the
components are unmodified, current, or the only UI layer.A lockfile entry → what would install.
node_modulesis what actually runs; if behaviour
contradicts the lockfile, the installed tree is the tiebreaker.
Checklist
- [ ] The
package.jsonread is the one governing the file being changed - [ ] Package manager identified from the lockfile, not from habit
- [ ] Framework and styling versions taken from the lockfile
- [ ] Routing/rendering model confirmed from the directory layout
- [ ] Dev, build and test commands quoted from
scripts - [ ] At least two real source files read for convention
- [ ] Unknowns written down rather than filled in by assumption
Failure handling
No lockfile — versions are unknown. Say so; do not resolve the range in your head. Behaviour
that depends on a major version has to be checked against the installed tree or the docs.Conflicting signals (two lockfiles, a config for a tool that is not installed, a framework
version that contradicts the layout) — report the conflict. Picking one silently makes you the
source of the next bug.Vendored or patched dependencies (
patches/, resolutions/overrides, a checked-in fork) —
upstream documentation may not describe what runs here. Read the patch.Detection disagrees with the user — say what you found and where, then follow the user.
Do not quietly rewrite their description of their own project.
Evidence to report
A short stack block — package manager, framework and version, router/rendering model, styling
layer and version, component layer, TypeScript posture, test setup, dev/build/test commands — with
the file each line came from, followed by an explicit "not determined" list. A stack summary with
no file references is a guess with formatting.