Slate v2 IME / Mobile / Browser Next Batch Plan

Purpose

Concrete next batch under the authority of 2026-04-11-slate-v2-ime-mobile-browser-zero-regression-rc-consensus-plan.md, using the current behavior/parity ledger as the gate truth.

This is not a new architecture plan. It is the next proof-recovery batch.

Constraint

Follow the consensus plan’s actual order:

1. recover currently missing proof rows
2. prefer real user-visible behavior proof
3. do not overclaim from proxy/setup wins
4. keep the behavior ledger as execution authority

Current Read

From 2026-04-11-slate-v2-ime-mobile-browser-file-ledger.md:

• Chromium IME rows are green
• Firefox/Desktop WebKit proxy composition rows are green
• Firefox/Desktop WebKit selection/focus rows are green
• Android browser-mobile setup proof is green through Appium
• Android placeholder input proof is explicitly red
• iOS Simulator setup/open/initial snapshot proof is green
• iOS post-input capture is still flaky

Still-blocking rows:

1. Android composition / diff / flush
2. iOS Safari / WebKit composition / focus
3. Firefox composition / selection recovery

Decision

Do not widen into more architecture or package design work yet.

The highest-leverage next batch is:

1. iOS post-input hardening
2. Firefox direct composition follow-up only if iOS stalls
3. do not spend more time on Android input API roulette until iOS is either green enough or proven equally dead

Why this order:

• Android already has a real browser session and a clean red proof. We know the problem.
• iOS still lacks the equivalent post-input readback seam, so the lane is less mature.
• Firefox is already further along than both because proxy composition plus direct browser selection/focus are green.

Batch Goal

Move one currently blocking row from:

• manual-device-blocking or vague setup-only status

to at least:

• automated-proxy with useful post-input evidence

without changing the RC claim yet.

Batch Scope

In scope

• agent-browser iOS Simulator post-input capture
• the current IME debug overlay and artifact readback on iOS
• one packaged proof command that goes beyond open + initial snapshot
• ledger/doc updates for the exact new evidence class

Out of scope

• new package architecture
• agent-device spike
• paid/cloud device labs
• broad Android refactors
• calling the iOS row closed unless the proof actually becomes trustworthy

Concrete Steps

Phase 1: iOS post-input readback matrix

Probe, in this order:

1. open + focus + keyboard inserttext
2. post-input debug JSON readback
3. post-input artifact markdown readback
4. post-input screenshot

Acceptance:

• at least one post-input readback path is repeatable enough to become the next iOS proof primitive

Failure rule:

• if all four still fail or hang, record iOS as setup-only and stop the batch there instead of inventing a fake proof story

Phase 2: package the winning iOS proof path

If a post-input path works:

• add a dedicated command under package.json
• keep it narrow
• prefer placeholder first
• update the current proof note and behavior ledger

Phase 3: only if Phase 1 fails hard

Use the remaining time for Firefox direct composition follow-up:

• try to upgrade the Firefox row from proxy-only composition to a stronger direct browser interaction path

Do not do this first.

Verification

Required fresh evidence in the same turn:

• pnpm lint:fix
• the packaged iOS proof command if one lands
• otherwise the exact shell probe output that proves the dead end

Closeout Rule

A good batch outcome is one of:

1. green primitive
   • iOS post-input readback is real enough to package
2. useful red
   • iOS post-input is still dead, but now with a tighter documented boundary

Bad batch outcome:

• more setup churn
• more transport swapping
• broader architecture debate without new proof