Anchors: the evidence
Sort your library by capture time and every photo without a location sits somewhere between photos that have one. Those geotagged neighbours are the photo's anchors. If you photographed the fountain at 14:02 with your iPhone, shot the same scene on your camera for half an hour, and photographed the bridge at 14:36 — the camera photos happened between those two known places. That is the entire idea, applied carefully.
Groups: the unit of review
Untagged photos that share the same pair of anchors, come from the same camera and span a short stretch of time are reviewed as one group. A morning at the market is one decision, not forty. Every photo in a confirmed group receives the same location — the app deliberately does not pretend to know that one shot was forty metres further down the street.
Confidence: what the app will and won't claim
Each group is classified by the distance between its anchors, the time between them, and the speed that implies. The class decides what you see on the map:
| Class | Evidence | What the map shows |
|---|---|---|
| Certain | Shot within seconds of an anchor, or both anchors at the same spot | A pin the app is not guessing about |
| Likely | Anchors close together, a walkable pace between them | A time-weighted pin, worth a glance |
| Uncertain | A flight, a long gap, anchors far apart | No pin. A dashed route and the honest facts |
| Manual | You dragged the pin yourself | Your placement, marked as yours |
The integrity rule: an uncertain proposal has no coordinate at all inside the app — so no screen, ever, can render a confident pin for a guess the engine cannot justify. Honesty is enforced by the architecture, not by a coat of paint.
Two details keep the honest cases honest. A burst shot seconds after an anchor is certain even when the rest of its group is not — the strongest signal is never dragged down. And every time window is judged against the group's furthest photo, never its nearest, so one lucky sibling can't vouch for a photo taken hours later.
The timeline bar
Every group card carries a bar: before-anchor, gap, after-anchor — with widths drawn to real elapsed time. A four-minute gap is a sliver you confirm without thinking. A six-hour gap is a wide band you instinctively distrust. It communicates confidence without printing a single number.
Review: a few swipes
- Confirm places every photo in the group at the proposed point.
- Swipe skips the group — it returns next session.
- Drag the pin anywhere to take over; the group becomes Manual.
- Tap opens the group's grid to pull out a stray photo.
- Groups the app is certain about can be accepted in bulk before you make a single swipe.
Apply & Undo: writes you can trust
Nothing touches your library while you review. Decisions are staged locally and written only when you press Apply — and before a single photo is changed, every write is recorded in a journal together with the photo's prior location, even when that prior location was “none”. If the app crashed mid-write, the journal would still be complete.
Undo replays the journal in reverse and restores every photo to exactly what it was. A photo you've edited since is skipped and reported — never overwritten. Prefer not to write to the library at all? Export the confirmed placements as a GPX track instead.
