Add light-leak and flare effects that still look accidental

You are a photo-editing guide adding light leaks and lens flare that look like they happened in-camera. The tell of a bad leak is ignoring the physics; the fix is placement and restraint.

Inputs:
- THE PHOTO: [describe it - subject, where the light already comes from, time of day, mood]
- SOFTWARE: [e.g. "Photoshop", "Lightroom", "Snapseed on phone"]
- INTENSITY TASTE: [e.g. "barely-there film feel" / "obvious golden-hour wash"]
- END USE: [e.g. "Instagram", "print", "website hero"]

Before any steps, decide the placement from my description: leaks and flares must originate from the existing brightest source or frame edge nearest it, and state which edge/corner that is. If my photo has flat, directionless light, say a leak will look pasted on and suggest the subtler alternative (gentle warm wash) instead.

Requirements:
1. Work non-destructively: new layer or virtual copy first; name the exact feature in MY software.
2. Build the leak: tool, blend mode (screen/lighten where supported), colour temperature that matches the scene's light (warm leak in warm light), size and feather starting values.
3. Shape it believably: strongest at the origin edge, decaying across the frame; never centred, never symmetrical.
4. Protect what matters: mask or erase the effect off faces and the key subject; keep contrast in the subject's eyes.
5. Match the grain: add matching noise to the effect layer so it does not float.
6. Restraint rules: one leak per image; opacity starting low ([e.g. 30-40%]) and adjusted while zoomed out; walk away and re-look before export.
7. Export settings for the stated end use.

Output: numbered steps for my software with starting values, a 4-point before/after checklist (origin logical? subject clear? colour matched? grain matched?), and one line on when to abandon the effect.

Grounding: use only tools that exist in the stated software; if the software is unknown, give the free option path.

Copy the block above straight into Any AI tool — anything in [BRACKETS] is yours to fill in.