[TrystonPerry]

Summary

Every edit deep-cloned the whole collection, and every snapshot rebuilt every document. One field change gave every document a new object, so React.memo and useMemo in consumers could never skip work.

• Edits: applyDiff copies only the objects on the changed path. Siblings and unchanged nested objects keep their identity.
• Snapshots: each document and nested object that equals the current view is reused (replaceEqualDeep). This covers the confirmation of our own write and server write-backs during a pending edit.
• No in-place mutation: id injection, the rebase, remote deletes, add, remove, and serverTimestamp() display overrides copy on write.
• Dev freeze: outside production, notify() deep-freezes syncState and localState. An in-place mutation throws a TypeError instead of silently corrupting the diff baseline.
• Docs: README.md, docs/, and AGENTS.md describe the immutability contract.
• Version: 0.2.0.

Breaking change

State is immutable. Non-production builds throw a TypeError when code mutates data read from Firestate. applyDiff results share unchanged subtrees with their input.

Tests

• New src/__tests__/structural-sharing.test.ts: edits, one-document snapshots, write confirmations, write-back during a pending edit, add and remove, undo, and the freeze.
• New src/utils/diff.test.ts for the diff helpers.
• 284 tests pass. Typecheck and build are clean.
• The HVAKR app suite (2,583 tests) passes against this build. Only 4 of 368 app test files use a real Firestate store, so the dev app is the real check for in-place mutations.

Release

After merge, publish a GitHub release for v0.2.0 to trigger the npm publish workflow.

🤖 Generated with Claude Code

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