PR 26720, exact head 85638d9f958cc9bc2958c371b4fbf49cf9d7cee4
Baseline github/main: 5732bbee39
Browser: repository Playwright, /usr/bin/google-chrome, Linux, 1440x1000.
State: fresh task-local databases, projects and threads created in the web UI.
Provider: Codex gpt-6.1-sol through the configured local proxy.
Main: COMPOSER_BASELINE_OK received.
PR: COMPOSER_BASELINE_OK and COMPOSER_CONTEXT_OK received.
PR: README file mention inserted using autocomplete, restored after reload, submitted.
PR: selection replacement and undo preserved draft.
PR: serialized rich-text clipboard output identical before and after reload.
Instrumented actual Vite-served serializer in browser only; no repository edits.
24,938-character draft; actual keyboard events, 30 typed keys then 30 arrows.
Main: typing 120 calls, 120 full walks, 32.20ms total serializer time.
PR: typing 120 calls, 30 full walks, 14.90ms total serializer time.
Main: arrows 90 calls, 90 full walks, 32.40ms total serializer time.
PR: arrows 90 calls, 0 full walks, 0.10ms total serializer time.
These are single capture serializer timings, not end-to-end latency or allocation measurements.
Blacksmith: 239 serializer unit tests passed.
Blacksmith: 18 existing composer browser tests passed (input, citation draft, list split).