[Feature] Support for captureIdentifier (PhotoIdentifier/DocumentID) to group photo variants #stacking #versions #edits

[trommegutten]

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request.

• Yes

The feature

Description

Immich today assigns a unique asset ID per file, which works well for file uniqueness.
What is missing is a systematic way to detect that multiple files are variants of the same photo capture (e.g. iOS original + portrait edit, or RAW + exported JPEG).
Without this, stacking relies on manual action or fragile heuristics (like filenames + timestamps).

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Proposed behavior

On import (XMP sidecar takes precedence if present), Immich should ingest a capture identifier in this priority order:
1. PhotoIdentifier (Apple, HEIC/ProRAW)
2. XMP:DocumentID (Adobe/XMP workflows, some Android/RAW)
3. If neither exists → autogenerate a new UUID and store it as captureIdentifier

If two or more assets share the same captureIdentifier:
• Suggest auto-stacking (non-destructive, reversible).
• Use the identifier for duplicate review and version management.

Database change:
• Add one nullable field to asset:
• captureIdentifier TEXT NULL

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Why not use other metadata IDs?

Several existing fields are not reliably unique or stable enough:
• Exif:ImageUniqueID → Often missing, reused, or inconsistently written by vendors.
• Filename + timestamp → Altered by export, AirDrop, editing, timezone shifts.
• XMP:InstanceID → Changes on each save; cannot link original + edits.
• Device/local IDs (e.g. deviceAssetId) → Platform-specific, not portable, don’t survive migration.
• Heuristics (time + camera model + GPS + perceptual hash) → Helpful as fallback, but probabilistic; can misgroup bursts or HDR brackets.

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Why PhotoIdentifier and DocumentID?
• Apple PhotoIdentifier → 128-bit UUID that remains constant across original + edited/portrait variants. Represents one capture.
• XMP DocumentID → Stable 128-bit UUID persisting across edits/exports in RAW/Adobe workflows.

Both are true UUIDs:
• Length: 128 bits
• Possible combinations: 2^122 ≈ 5.3 × 10^36 (practically collision-free)

They are deterministic, extremely collision-resistant, and widely used in real workflows.
They align with Immich’s non-destructive policy: multiple versions, one capture.

When these are missing, an autogenerated captureIdentifier ensures every asset still belongs to a capture group, even if only containing itself.

Platform

• Server
• Web
• Mobile

[bo0tzz]

#2479