[softglazee]

What was broken

Smart Autofill (Data Vault) left forms empty or garbled.

1. Nothing filled with "Minimize CDP footprint" on. rebrowser's enableDisable mode resolves the main world to a blank about:blank context on fingerprint-chromium, so page.$ returned null for every tagged field and the fill failed in ~10 ms ("Could not fill this form - nothing was entered").
2. Garbled text with the stock engine. The trusted focus click hit whatever covered the field - usually the open autofill panel - which clicked another identity row and started a second fill. Keystrokes from both interleaved in every field.
3. No feedback. The result toast rendered underneath the panel, squeezed to the 48 px host width.

Multi-step signups lost the identity after step 1, because it was marked used immediately; it disappeared from the list and later steps had nothing to fill with.

What changed

• browserEngine.js: the fill loop does all DOM work in the widget's isolated world (personaPrepareTarget / personaFocusTarget / personaIsFocused / personaCommitTarget / personaSetSelect). A click is used only when elementFromPoint hits the field; otherwise DOM focus. Focus is re-checked before every keystroke. Fill plans are serialized per tab.
• Active identity per site (registrable domain, 30 min idle, per browser session): new __sgPersonaActive handler; mark-used uses the URL recorded when the identity became active and then releases it.
• personaAutofill.js: picking an identity closes the panel and blocks a second pick while filling; a fill makes the identity active instead of marking it used; later steps (same page, SPA route change, or a new page) auto-fill empty fields - never the password; the final submit (Sign up / Register / Submit / Create account / Finish ...) marks it used while Next / Continue keep it; panel pins it as "In progress" with Mark as used / Release; toast fixed.
• pageBridge.js: keepalive on the fetch transport so a mark-used sent during the final navigation still lands.
• Firefox: sg-bridge.js / sg-background.js keep the active identity per tab + site; sg-widget.js regenerated. The signed .xpi still needs re-signing to ship these to Firefox profiles.

Testing

• npm test: 648/648 on this tree (test/autofillFillEngine.test.js is new).
• Reproduced and verified in fingerprint-chromium 148 on both the stock and rebrowser engines: a live Marketo demo form, a local signup with select / date / password + confirm, and a 3-step signup (in-page Next, route change, full page load, password step, Create account).
• Verified in the installed app (Minimize CDP footprint on): identity fields fill correctly; on the 3-step signup the identity stayed unused through every step and was marked used only on Create account.

Stacked on #14.