US09-04: Write the User Manual with Generated Screenshots (#110)

docs/stages/duplicates.md

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+# Duplicate review
+
+[← Documentation index](../index.md) · [Guided first pass](../first-pass.md)
+
+![The duplicate cluster list](../images/duplicates.png)
+
+**What it is for.** Deciding which file is *the* copy of a picture, before anything
+expensive or irreversible happens to the others.
+
+**What you decide.** For each cluster: keep the recommended canonical, choose a
+different one, keep everything as variants, declare it not a duplicate, or defer.
+
+**What it changes.** Only the decision, recorded as an auditable event. **No file is
+ever deleted.** Non-canonical copies stay exactly where they are; they are simply
+excluded from analysis and upload.
+
+**What it refuses.** Exact byte and identical-pixel matches may be accepted on the
+recommendation. Anything fuzzy — a crop, a re-encode, a burst frame — requires an
+explicit confirmation, because a perceptual hash is evidence, not proof.
+
+## Reading a cluster
+
+Each member shows its path, role, pHash distance, and size, with synchronised zoom
+across the previews. The recommendation is visible but never pre-applied for fuzzy
+matches. The confidence band tells you how much the machine is claiming.
+
+Rejecting a pair records a negative link, so a later rescan does not keep proposing
+the same wrong match.
+
+## Why first
+
+Resolving duplicates before safety and analysis is what stops you reviewing and
+paying for the same photograph three times. It also means the album evidence is built
+from one copy of each picture rather than a skewed count.
+
+Next: [safety review](safety.md).