dep-resolver.ts

Create the default ImportResolver (TypeScript + tsconfig).

Uses ts.resolveModuleName against host (default ts.sys) — no ts.Program is built. Identity is a fresh symbol per call, so each session that constructs its own default gets a unique cache scope. Multiple sessions sharing one resolver instance share the cache scope (correct, since resolver state is shared too).

ts.resolveModuleName cannot resolve real .svelte files (no compiler option teaches it the extension), so relative and absolute .svelte specifiers — with or without the extension written — fall back to manual resolution against fromFile through the same host. Non-relative .svelte specifiers (tsconfig paths aliases, package subpaths) stay unresolved; supply a custom resolveImport for those setups.

The resolution cache lives for the resolver's lifetime and caches failed lookups alongside successful ones, so invalidate clears it — the session calls that whenever its owned set's membership changed (see ImportResolver).

Ensure es-module-lexer's wasm runtime is initialized.

Idempotent and cheap after the first call. The session awaits this once at the top of setFiles so phase 1's per-file lex is purely synchronous.

Token-paired import resolver.

identity is a stable opaque token that keys the session's resolve cache alongside content. Cache hits require both (a) byte-for-byte identical source content and (b) identity equality. Naive function-reference keys would silently destroy cache reuse when callers wrap the resolver in fresh closures (a very common pattern in Vite/Rollup plugins) — opaque tokens lift the responsibility to the caller, where it can be done correctly.

Whether a lexed specifier names a Node builtin (fs, node:fs/promises, …).

Builtins can never be a project source file, so resolving them is pointless — and routing them through a host resolver (Vite/Rollup) makes that host emit "externalized for browser compatibility" warnings for browser-targeted configs. Callers skip resolution for these and treat them as unresolved (null), which the downstream isSource filter would do anyway.

Lex import specifiers from prepared content.

Sync — caller must have awaited ensureLexerReady at least once before invoking. For .svelte files, pass the svelte2tsx-transformed virtual content, not the raw .svelte source (which isn't lex-able as JS/TS).

Dynamic imports (import(specifier) with non-literal arg) are omitted.

Shared no-op ImportResolver for the "dependency resolution disabled" case.

Stable string identity ('no-deps') instead of a per-call symbol so that repeated ingests within a long-lived session cache-hit on identity. Each session still owns its own cache (entries live on the per-session owned map; sessions don't share state), but within one session every reference to noDepsResolver is === to every other — so a Vite re-save of byte-identical content with resolveDependencies: false exercises the cache-hit branch. The resolver always returns null, so any two calls with identical content under this identity produce identical resolution results — string identity correctly captures that. Used by both the one-shot analyzeFromFiles path and the long-lived Vite plugin (resolveDependencies: false).

Normalize the public ResolveImport union to an ImportResolver.

Wraps a bare function via wrapResolveImport (fresh synthesized identity); passes a token-paired resolver through unchanged. undefined in, undefined out — callers fall back to the session default. Call once per logical resolver scope: at session construction for the default, per call for an override.

Public resolver shape accepted across the API — a bare ResolveImportFn or the token-paired ImportResolver.

Every entry point that accepts resolveImport (analyze, analyzeFromFiles, createAnalysisSession, and the session's setFile/setFiles per-call override) takes this union, so the same value copy-pastes between them. Pass:

• a bare function for the common case — a fresh cache identity is synthesized at the boundary. Correct for one-shot use (analyze, analyzeFromFiles) and for a session default (wrapped once at construction, so identity is stable for the session's lifetime).
• an ImportResolver with a stable identity when you need the session to reuse its resolve cache across calls where the same logical resolver is rebuilt as a fresh closure (Vite/Rollup plugins). A bare function handed to a *per-call* setFile/setFiles override is treated as a distinct resolver each call (fresh identity → touched files re-resolve), which is the expected behavior for a deliberate one-off override.

Bare import-resolver function — the convenience form.

Resolve an import specifier to an absolute file path, or null if the specifier is unresolvable (external package, missing file, etc.). May return synchronously or asynchronously; sync returns are awaited harmlessly in the session's parallel resolve phase.

Wrap a bare resolveImport function into an ImportResolver token.

identity is optional; when omitted, a fresh Symbol('wrapped') is synthesized per call. The synthesized default suits single-use scopes — normalizeResolveImport relies on it to wrap a bare function for a one-shot analyze call or for a session default (wrapped once at construction, so the identity stays stable for the session's lifetime).

For a long-lived session that re-wraps the *same* logical resolver across calls (Vite plugin, LSP), a throwaway identity cache-misses every time — the fresh Symbol('wrapped') never compares equal. Pass a stable identity here, or — simpler — construct an ImportResolver ({resolve, identity}) directly and pass it through the ResolveImport union.