Task: Finalize AI design session freeze promotion

Identity

Finalize the user-authorized promotion of the reviewed AI Design rapid Conversation-switching fix, already present at canonical main 803e3d8.
Record the completed promotion and its canonical verification without changing product behavior or rewriting existing history.

Operate in an exclusively owned Integration Gate worktree with the integration lock.
Keep the source feature task and prior integration task records read-only; this task records only the final promotion evidence.
Leave main clean and ahead of origin/main by the intended local integration commits; publishing remains a separate release action.

main was fast-forwarded from 31332f6 to 803e3d8 after explicit user authorization to take over the clean worktree. No existing commit was reset, overwritten, or conflicted.

check_project_docs.py --target . passed before promotion.
git merge-base --is-ancestor 31332f6 803e3d8 passed and git merge --ff-only 803e3d8 completed successfully.
Canonical main: tests/unit/image-workspace-store.test.ts 31/31; tests/unit/image-canvas-page.test.tsx plus tests/unit/works-square-design-workspace.test.ts 79/79; scoped ESLint; TypeScript --noEmit all passed.
Existing React act(...) warnings appeared in the adjacent Canvas test and did not fail the suite.
Final task-aware documentation drift, git diff --check, and clean-worktree checks will run after this record is committed.

Run the real logged-in Electron slow-handshake Conversation-switching smoke from the source task; local tests do not claim production gateway behavior.
Publish local main commits through the normal repository review/release process when desired.

None. The reviewed fix is now present on canonical main and restores the existing stream-lifecycle invariant.