refactor(kernel-platforms): fs promises-only - #1055
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Remove `existsSync` from the fs capability, its config field, and the synchronous operation wrapper it was the only user of. Narrowed methods always forward through `E()` and every derived guard is `M.callWhen`, so a synchronous method cannot survive narrowing. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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added this pull request to stack #1060
September 11, 2026 11:44
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Explanation
Removes
existsSyncand all synchronous operation from thefsplatform capability: theFsCapabilitymember, thefsConfigStructfield,makeCaveatedSyncFsOperation, and the node and browser sync variants.Why: narrowed methods always forward through
E()and every derived guard isM.callWhen, so a synchronous method cannot survive narrowing. Going promises-only is a precondition for vendingfsas a narrowable exo in the next two PRs.makeNoSymlinksCaveatand itslstatSyncare untouched — patterns cannot see the filesystem, so anti-aliasing stays in the base implementation and narrowings inherit it by forwarding.Deletion-dominated: +8 / −189.
Notes for reviewers
This is the first of a three-PR chain (9a → 9b → 9c) intended to squash to a single commit on
main, so thatmainsees one breaking change to@metamask/kernel-platformsrather than three. Intermediate states never ship. The changelog entry therefore lands only in 9c — its absence here is deliberate, not an oversight.One migration the plan for this work had claimed was unnecessary.
packages/ocap-kernel/src/types.test.tspassedplatformConfig: { fs: { rootDir: '/tmp', existsSync: true } }and assertedisVatConfigreturnstrue. SincefsConfigStructis asuperstructobject(), it rejects unknown keys, so removing the field would have silently flipped that assertion tofalse. Now usespromises: { readFile: true }so the case still exercises a populated fs config.SyncPathCaveatis kept — it does not become unreferenced, because the caveats themselves stay synchronous even though the operations do not.Breaking for
@metamask/kernel-platforms, intentionally and with no compatibility shim.Stack
PR 9 of 12. Base: #1054.