ekp/.phrase/phases/phase-kp-overhaul-20260726/change_hot_loop_performance_20260728.md

Change Log: Hot-loop Performance 2026-07-28

task012

• Modify — ekp-utils.el

  • Accumulate tokenizer box fragments in reverse and concatenate once when a box is emitted.
  • Preserve zero-width attachment and text-property behavior.

• Modify — ekp-hyphen.el

  • Distinguish cache misses from cached nil with an uninterned sentinel.
  • Build dense inserted output from original word slices in one concatenation.

• Modify — tests/ekp-tests.el, tests/ekp-bench.el

  • Add nil call-count, long propertized token, and dense insertion regressions.
  • Add reusable 1k–8k adversarial builder measurements.

• Modify/Add — developer/audit/issue documentation and postmortem/20260728-linear-text-builders.md

  • Record the evidence threshold, measurements, ownership decision, and rollback boundary.

Validation

• Nil cache red/green: 0/1 → 1/1; focused behavior tests: 3/3.
• Source-mode 8,000-character tokenizer: 3.133 s → 1.100 s.
• Source-mode 8,000-character dense insertion: 0.945 s → 0.013 s.
• Full ERT: 124/124; C/Elisp fuzz: 300/300.
• Warning-as-error production byte compilation and production checkdoc: pass.

Behavior and Risk

• Public tokenization and hyphenation output is unchanged.
• The cache now retains negative results until its existing invalidation boundary.
• The implementation adds no builder abstraction or dependency.