Collision kerning

The kerning_collision job checks explicit left-to-right glyph pairs against a requested sampled clearance. It loosens collisions by creating or updating pair exceptions while leaving shared group values intact.

{
  "document_id": "<document ID>",
  "kind": "kerning_collision",
  "options": {"pairs": [["A", "V"], ["T", "o"]], "targetGap": 5, "denseStep": 10}
}

Pass pairs in options.pairs; do not pass glyphs or delta. options.masters limits the master IDs, otherwise all masters are considered. The default target gap is 5 font units and dense step is 10.

Review before applying

The worker resolves native groups and exceptions, performs a coarse scan and refines near the target. get_job reports native effective values, stored exceptions, class keys, sampling density, minima and unavailable pairs. Inspect the full report when the compact sample is insufficient.

The result only loosens a pair toward the sampled target. It does not generate an optimal optical-kerning system or guarantee clearance between sample heights. RTL and vertical kerning storage can be read, but this collision geometry workflow accepts LTR only.

Verify the result

After apply_job completes, review the chosen pairs in Glyphs across the affected masters. Read the exact exception using read_entities with a kind="kerning" selector and fields=["value"]. An absent value is null; zero is a stored value and is not interchangeable with absence.

Native Undo/Redo retains exact values and exception presence. discard_job restores the job's current targets; when persistence is authorized, accept_job verifies the targets and saves the whole document. See Safety and recovery.