Rename freshness

Two verbs read a file's text by different routes. compile, which builds the virtual code the editor shows, reads the open buffer through editorSource. diagnose, which produces the diagnostics, reads the compiler's DocumentSource — and in the editor that is raw disk. LoomMemo hides the split for a while: compile caches each module it builds from the buffer, and diagnose reuses that cache. But on a miss diagnose falls through to disk, and before a save disk holds the old text. So the corpus diagnose walks is a mix — some modules fresh from the buffer, some stale from disk — and a member that resolves in the buffer fails against the stale copy.

This never shows in a test. Every test feeds one in-memory source to both verbs, so the two always agree and diagnose is clean. The gap is the editor's alone, which is why it survived a green suite.

The tempting fix is to have editorSource read a sibling from Volar too, through ctx.getAssociatedScript. But that call registers an association, and registering one makes Volar project the sibling — so reading a sibling mid-build would re-enter the projector. The current disk read is a deliberate guard against exactly that: the source never calls back into Volar.

Keep one source of truth for a file's text — the editor's live buffer — and let both verbs read it without calling back into Volar. The plugin already sees every buffer: Volar hands it each snapshot as it creates, updates, and disposes a virtual code. So the plugin keeps those snapshots in a small registry and reads from it, passively, wherever a file's text is needed — editorSource for a sibling, and the compiler's DocumentSource for diagnose. A file the editor never opened is absent from the registry and still comes from disk, as it should.

The registry is the project's open buffers, held the way LoomMemo holds its cache: behind a SynchronizedRef, updated by the plugin's hooks. This chapter grows its code here — the registry service, and the two reads rerouted through it. When the diagnostic clears on an unsaved rename in the editor, the chapter graduates to Part VII.