test: give the suite a real localStorage on Node 25

[ivanmkc]

The stack

#	PR	What it adds	Tests at this point
1	#311	A real localStorage for the test suite on Node 25	viewer 747
2	#312	@ivanmkc/termchart-canvas; injectable interact transport	canvas 473 · viewer 278
3	#313	lifeboard PWA: fact log, boards, service worker	lifeboard 36
4	#314	Shell, family profiles, tap layer	lifeboard 82
5	#315	The agent turn, four providers, Connections	lifeboard 142
6	#316	Packs, recipes, shopping-list arithmetic	lifeboard 231
7	#317	Provenance and lineage	lifeboard 257
8	#318	Calendar, Gmail, mail triage	lifeboard 301
9	#319	The bridge and long jobs	cli 314 · lifeboard 320
10	#310	Proactivity, scheduled boards, Google sign-in	cli 320 · lifeboard 343
11	#320	Persistence audit fixes: multi-tab, stale builds, no-storage boot	lifeboard 350
12	#321	User guide, bridge setup, QA guide, persistence audit	lifeboard 350
13	#322	A plan for third-party integrations (docs only)	unchanged
14	#323	A practice drill a board can define: audio + Q&A	canvas 485 · lifeboard 372
15	#325	Export and restore	lifeboard 389
16	#326	Draft a message, approve it, then send	lifeboard 399
17	#327	Hand long work to the Mac	lifeboard 406
18	#328	A Packs screen, and authoring one by describing it	lifeboard 418
19	#329	Activity — what changed, who changed it, undo	lifeboard 428
20	#330	Four defects found reviewing the stack	cli 323 · lifeboard 431

Every branch in the stack was checked out on its own and verified independently: npm install, tsc --noEmit for every package, npm test across the workspace, and the offline e2e where it exists. All twenty are green — no branch depends on a later one to build or pass. Full viewer e2e (11 suites, 106 assertions) was run on #312 as the behaviour-preservation evidence for the extraction.

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Stack position: 1 of 10. Base: design/lifeboard.

Node 25 defines a global localStorage whose methods do nothing unless the process was started with --localstorage-file. It is installed before the test environment gets there, and happy-dom's window is globalThis under vitest — so window.localStorage is the same stub, and there is no browser storage anywhere to fall back to.

Two tests have been failing locally on Node 25 while CI, pinned to Node 20 and 22, stays green. That is the worst shape a failure can have: it bites only the person running the tests, and only on a runtime newer than the one CI proves.

A setup file installs a Map-backed Storage instead — spec-shaped in the ways the code under test relies on: string values, null for a missing key, and length/key() enumerating in insertion order.

Verified: viewer 747 tests pass on Node 25 (was 746 passing, 1 failing).

🤖 Generated with Claude Code