fix(describe): stop ordering a simulator reboot on every externally-booted read

[latekvo]

Fixes #521.

The report holds, and is worse than described

Reproduced against an unmodified origin/main tool-server driving a simulator booted the way a developer boots one (plain xcrun simctl boot, no argent involvement), iOS 18.6:

===== describe call #1 =====   ===== #2 =====   ===== #3 =====
hint: "This simulator was not booted through argent — system dialogs and native
modals may not appear. You MUST call boot-device with force=true now to restart
the simulator and apply full accessibility settings before continuing."

Identical on every call, as reported. The part that makes it more than a wording nit is what came back alongside it — a complete, working tree:

ROOT  AXGroup (0.000, 0.000, 1.000, 1.000)
  AXStaticText "19:51"  (0.139, 0.023, 0.102, 0.023)
  AXGroup "Maps" value="Widget"  (0.082, 0.096, 0.395, 0.206)
  ...

And the caveat's own claim does not hold either. Triggering a real system permission alert on that same externally-booted sim (simctl privacy reset location com.apple.Maps + launch):

  AXGroup "Allow “Maps” to use your location?"  (0.193, 0.367, 0.614, 0.296)
  AXButton "Allow Once"  (0.193, 0.524, 0.614, 0.046)
  AXButton "Allow While Using App"  (0.193, 0.570, 0.614, 0.046)
  AXButton "Don’t Allow"  (0.193, 0.617, 0.614, 0.046)

The system dialog reads fine, buttons and all. So an agent obeying "You MUST ... now" restarts the simulator — killing the Metro session, dev client and staged app state — to fix nothing.

Root cause

AXServiceApi.degraded is !entitlementBypassActive, read from IgnoreAXServerEntitlements. That pref is only writable pre-boot, so boot-device is the only thing that ever sets it and any externally-booted sim reads as degraded for its whole life. The pref bypasses the AX-server entitlement check introduced in iOS 26.5 — on earlier runtimes it is irrelevant to whether the read works. The flag describes how the sim was booted, never whether describe succeeded, and the hint conflated the two.

Change

Resolve the caveat against what the accessibility read produced:

• Blind read — the reboot has something to gain, so the actionable guidance stays, on every call, and now names what the reboot costs.
• Populated read — the read is its own proof no reboot is needed. States the limitation instead of ordering anything, once per device per server lifetime.

The per-device gate is applied at the describe tool boundary only. await-ui-element, the flow runner and await-screen-idle poll describeIos directly, treat a present hint on an empty tree as "this emptiness is untrustworthy" (isBlindRead), and fold it into one terminal timeout note — they keep every copy, so a hidden wait still cannot resolve off a blind read.

The native-devtools fallback can fill a tree the accessibility read left empty, and that split has to key on the accessibility read rather than on the tree that comes back. Its elements are the injected app's own view hierarchy: no SpringBoard chrome, no system dialog, and no evidence the accessibility subsystem works.

Found doing exactly that on a fresh iOS 18.6 sim. Describing within seconds of simctl boot leaves the accessibility read blind for the rest of that boot (3/3; it survives a tool-server restart, and only boot-device force=true recovers it). With the Maps location prompt on screen in that state, the fallback returned the app's own 20 elements with the dialog absent — and resolving against that tree picked the standing note, which the per-device gate then deleted, so from the second call the agent had a tree silently missing a modal blocking the screen and no caveat at all. The note it briefly carried says "everything else reads normally", which nothing there did. Keying on the accessibility read makes both wordings true of the state that produces them.

I skipped the suppression env var / flag the issue floated as a "maybe" — once the caveat is a single non-directive line per device, there is little left to suppress, and it seemed better not to add config surface for it. Happy to add it if you'd rather have the switch.

Verification

E2E against the branch build, same externally-booted sim:

	elements	hint
describe #1	14	standing caveat, no MUST/now
describe #2-4	14	(none)
after simctl shutdown (blind) ×2	0	blind caveat, both times
after boot-device force=true ×2	28	(none) — IgnoreAXServerEntitlements = 1

Unit: 6 new tests in describe-tool.test.ts. Each was mutation-checked — restoring the MUST wording, removing the dedup, collapsing the blind/standing split, keying the gate globally instead of per device, and re-resolving the caveat against the native-devtools tree each fail exactly one test and nothing else.

Full gate: vitest run 4715 passed / 1 skipped, tsc --build, typecheck:tests, eslint --max-warnings 0, prettier --check, test:scripts 59 passed.