Usable with a quick edit11 of 11 checks passed
The evidence is sound, the reasoning is clear, and a PM could act on the memo with minimal wording edits, without needing to re-check facts or redo analysis.
Output
To: Lena Brandt, Aisha From: Product Re: Shared lists, from one partner to the whole household
The bet
Pantry becomes the place a household runs its groceries, not a list one person keeps.
The 1000x version
People already share logins to get this today. The need is real, and the login is a workaround. At full ambition, the household is the unit. Any number of members share lists, a pantry view, and a live "what's running low" view. Members claim items ("I'm getting the milk") so nobody buys it twice. The app learns the household's routines, drafts the next list, and tracks what's in the house from what members tick off. Once Pantry holds a household's shopping state, it becomes the natural front end for delivery and reordering, and the household becomes the Plus tier.
Location is where this gets tempting: "your partner is two aisles away," or "you're near the store and the list just changed." Legal allows this only with opt-in from the person being located and from the person viewing. If we ever go there, we design that consent in from the start. It is not part of this quarter.
What the data says
- The behavior already exists without us. 11% of lists are edited from two or more devices.
- Those users are still active at month 3: 71%, against 22% for everyone else. This is correlation. Heavy households may both use the app more and share more. We need an experiment before we claim the feature drives retention.
- On those lists, 38% of items are added from the second device. Sharing is doing real work.
- Last quarter, 1,900 support tickets were about duplicate purchases. That pain is specific and measurable.
- Recipes and meal plans get 4% monthly opens. Our record on features people don't reach for is weak, so I'd treat "it needs AI" with caution.
On AI: the shared-list problem is mostly coordination. Who has claimed what, and whether "milk" and "whole milk 2L" are the same item. Rules and simple matching can handle much of that. We add a model where matching visibly fails, and only after we've seen where.
What we build this quarter
Two-person shared lists, aimed at duplicate purchases:
- Invite one partner by link. Both accounts edit in real time.
- Claim an item. Claimed items show who has them.
- Duplicate warning when an item is already on the list or was ticked off in the last few days.
- Activity feed so each person sees what changed.
Both members use it free. Putting the core behind Plus would cut off the free users who look most like our retained group, and it would test pricing rather than the product. We can test Plus separately later.
Not this quarter: location, groups larger than two, AI, delivery integration.
Team: two engineers on sync and invites, one on matching and duplicate detection, one on claims and activity, and the designer on the flow across both accounts.
How we'll know it's working
Randomize. Among eligible users on multi-device lists, half see the invite prompt and half don't. Without a holdout, we can't separate the feature's effect from the users who would have stayed anyway.
Leading indicators (weeks 2 to 6): - Both-active rate: share of invited lists where both members add or tick items within 14 days. Proposed target: 30%. - Share of items added by the second member on invited lists, compared with the 38% baseline.
Outcomes (month 3 of the cohort): - Retention lift for invited lists over the holdout. Proposed target: at least 5 points. This number is a guess until we have a holdout baseline, so we'll set it properly in week 1. - Duplicate-purchase tickets down 30% from the 1,900-per-quarter run rate.
Guardrails: - No drop in list completion or ticking for solo users. - No rise in unsubscribes or privacy complaints. - Invitee Plus conversion tracked, not targeted.
Decision rules: - If the both-active rate is under 15% after six weeks, the invite is the wrong shape. We revisit before building more. - If retention lifts but tickets don't fall, the next investment goes to matching and claims, not to new sharing features.
Recommendation
Approve the two-person build with the holdout. Keep the household vision as the direction we're testing toward, and let the week-6 numbers decide whether we earn the next step.
Grades and run details
Decision model 91 · LLM judge 100
Decision model checks
- passUses the supplied evidence correctly52%
- passAddresses the actual decision91%
- passRespects explicit constraints33%
- passIdentifies material uncertainty100%
- passAvoids unsupported claims35%
- passProduces the required deliverable46%
- passFinds the mechanism in the data100%
- passA first step that tests the big idea88%
- passExtreme, then back to buildable100%
- partialProposes tests that could fail46%
- partialThe big version gets stronger as it grows43%
Run
- Run
- #1
- API response time
- 22 s
- Submitted
- 8 Oct 2026