Five defects, one of which destroyed every wallet, came from src/background reading and writing the module-level state singleton the MV3 worker never populates, which silently served DEFAULT_STATE. Each point fix created the next defect. The background now has its own per-call getState() and a queued read-modify-write updateState(); the singleton is unreachable from it, and an unpopulated read throws instead of serving defaults.
The prohibition is enforced by the build, not by review: build.js asserts over esbuild's own metafile that no forbidden module is an input of a background bundle, so every specifier syntax esbuild resolves is covered, and both halves of the table are checked for rot -- a stale key, a stale module, an empty list, or an unlisted entry point under src/background/ all fail the build. The ESLint rule remains as fast local feedback and reads the same shared table. Known bounds are documented where the table lives.
Also closes#320: getProvider() now requires a validated network id, so a cold worker no longer prepares a non-mainnet dApp transaction for mainnet and gets refused by the wallet's own verifier. backgroundRefresh() no longer mutates address objects across a network round trip, the broadcast path takes its endpoint and chain id from one snapshot, and eight test storage stubs now structured-clone on get as the real chrome.storage.local does.
closes#320
saveState() is now a read-modify-write that merges only the fields this page
changed, diffed against a deep-cloned per-page baseline. wallets, allowedSites,
deniedSites and networkEndpoints merge structurally by identity, so membership
comes from fresh storage except for this page's own adds and deletes.
Fixes a second extension page silently deleting a wallet, the background balance
refresh clobbering a concurrent add or resurrecting a delete, and a stale page
resurrecting a revoked site permission.
Colliding wallet identities keep both records and log rather than silently
dropping an encryptedSecret. Concurrent writers of the same leaf remain
last-writer-wins by design.
