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findings: JSR npm-compat consumption (layout split, deno package.json interactions) #100

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findings: JSR npm-compat consumption (layout split, deno package.json interactions) #100

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45 changes: 45 additions & 0 deletions docs/findings.md
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Expand Up @@ -254,3 +254,48 @@ bench-suite artifact built with its `wizer-init` feature.
must run, name sections explicitly with `--delete`; never the
default form.


## Consuming @polymorph/test from JSR (the consumer migration)

From migrating the four conformance drivers off the npm-git facade
onto `jsr:@polymorph/test` / its npm-compat form (webcrypto#385,
tls#46, websocket#55, webrtc-datachannels#162; deno 2.9.5, npm 11).

26. **One JSR package, two on-disk layouts.** npm's install of the
npm-compat package (`@jsr/polymorph__test` from `npm.jsr.io`)
extracts the compat tarball, whose files sit under the path prefix
the generated exports use; deno's own materialization of the same
dependency (package.json dep resolved by `deno install`) lays the
package out JSR-natively — module root = the package root, no
prefix. File paths into `node_modules/@jsr/...` are therefore
layout-fragile; only export-map subpaths and `jsr:` specifiers are
stable across installers. (This is what made browser-driver's
old `<pkg>/js/viewer/*` mount assumption fail — fixed in #97 by
mounting the module's own directory.)

27. **deno 2.9 cannot parse scoped npm aliases in package.json.**
`"x": "npm:@jsr/polymorph__test@0.1.0"` fails config parsing
("Unexpected character '/'"); a plain scoped dependency
`"@jsr/polymorph__test": "0.1.0"` plus `.npmrc` scope routing
(`@jsr:registry=https://npm.jsr.io`) parses and resolves in both
npm and deno.

28. **`deno install` scopes prune each other's node_modules.** In a
directory with both deno.json and package.json, bare
`deno install` (package.json scope) and
`deno install --entrypoint a.ts b.ts` (module-graph scope) each
re-materialize node_modules for *their* dependency set, removing
the other's packages. Sequence that holds: bare `deno install`
owns node_modules; `deno check <entrypoints>` adds the module
graphs to deno.lock without touching node_modules. Note the lock
then carries a `workspace.packageJson.dependencies` section every
deno subcommand (including `deno bundle --frozen`) recomputes —
package.json edits require a lock regen or --frozen fails on the
stale entry.

29. **`minimumDependencyAge` gates npm-form deps under their npm
name.** A same-day JSR publish consumed through the npm-compat
registry needs the `npm:@jsr/*` pattern excluded (or the jsr:
equivalent where the dep enters as a `jsr:` specifier) — the
`jsr:@polymorph/*` exclusion alone does not cover the npm-form
resolution path.
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