[ankit]

Migrations ran on every background start, forever. `chat-removal` read all of storage with `get(null)` each time, which is megabytes for big profiles.

• The runner now records a `migration_` completion key after a migration succeeds, and skips it on later starts. All keys are read in one targeted `get`.
• `everyStart: true` opts out. Only `styles-metadata-update` and `styles-modified-time-update` use it, because synced data can still need those repairs.
• `chat-removal` and `commands-to-browser` drop their own flag checks. `commands-to-browser`'s old flag already matches its new key.

Review notes: `default-shortcut-update` and `sync-storage-update` keep checking their legacy flags, so upgraders run each one last time as a no-op before the new key is set. A migration that throws gets no key and runs again next start.

Testing: runner tests cover recording keys, skipping done migrations, `everyStart`, and a failed read. Typecheck, lint and `yarn test` pass.

🤖 Generated with Claude Code

[github-actions]

Bundle size

No change to what the popup or content scripts load.

Bundle	Size	Change	Gzip	Change
Popup	174.7 KB	–	48.1 KB	–
fonts/fonts.css	2.9 KB	–	458 B	–
popup/index.css	23.3 KB	–	5.2 KB	–
popup/index.js	148.5 KB	–	42.5 KB	–
Content script (document_start)	78.5 KB	–	21.2 KB	–
editor/index.js	40.2 KB	–	10.2 KB	–
inject-css/index.js	35.2 KB	–	9.6 KB	–
site-bridge/index.js	3.1 KB	–	1.4 KB	–