test: Wait for native view lifecycle completion

[mrousavy]

Harness rerender completion does not establish that Fabric has finished applying native props or recycling a removed view. The tests could therefore read old setter or lifecycle counts, particularly under sanitizer scheduling overhead.

Wait for changed hybridRef callbacks after prop updates and for the exact drop/recycle counts after removal. Publish lifecycle counts across the UI and JS threads using Android atomics and an iOS lock; publish recycle completion after resetting native state. This extracts only the view lifecycle changes from #1530 and uses Foundation's existing NSLock.withLock instead of custom locking helpers.

Validation:

• Workspace packages build; example TypeScript and targeted ESLint pass.
• Swift format lint and Kotlin lint pass. NSLock.withLock type-checks against the iOS 15 simulator target.
• Confirmed in generated native view bindings that prop setters run before the changed hybridRef callback.
• git diff --check passes. Fresh native builds and Harness tests run on this PR; earlier full Android validation is recorded in Stabilize Android Harness ASan and view lifecycle tests #1530.

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1 Skipped Deployment

Project	Deployment	Actions	Updated
nitro-docs	Skipped		Sep 5, 2026 1:02pm UTC

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Performance Report

⚠️ Advisory: Results do not fail this PR while the baseline is being calibrated.

iOS

Benchmark	Before	After	Difference
Swift bounce(4 KiB)	529.4 ns	451.1 ns	🟢 -14.78% faster
Swift copy(1 MiB)	94.21 µs	107.81 µs	🔴 +14.43% slower

All Benchmarks

Benchmark	Before	After	Difference
JavaScript addNumbers()	33.1 ns	35.2 ns	🟡 +6.13% slower (noisy)
C++ bounce(1 MiB)	391.9 ns	391.3 ns	🟡 -0.17% faster (noisy)
C++ bounce(4 KiB)	433.6 ns	383.7 ns	🟡 -11.5% faster (noisy)
C++ copy(1 MiB)	100.51 µs	89.07 µs	🟡 -11.38% faster (noisy)
C++ copy(4 KiB)	1.47 µs	1.51 µs	🟡 +2.19% slower (noisy)
C++ large array (1,024)	58.53 µs	58.06 µs	🟡 -0.8% faster (noisy)
C++ small array (16)	1.11 µs	1.21 µs	🟡 +8.77% slower (noisy)
C++ synchronousCallback()	335.6 ns	339.7 ns	🟡 +1.25% slower (noisy)
C++ create()	577.8 ns	622.6 ns	🟡 +7.77% slower (noisy)
C++ returnExisting()	287.5 ns	283.9 ns	🟡 -1.27% faster (noisy)
C++ typed map (8 entries)	2.27 µs	2.23 µs	🟡 -1.52% faster (noisy)
C++ optional trailing string	222.0 ns	224.7 ns	🟡 +1.22% slower (noisy)
C++ addNumbers()	122.8 ns	126.1 ns	🟡 +2.64% slower (noisy)
C++ simpleFunc()	103.4 ns	108.1 ns	🟡 +4.58% slower (noisy)
C++ immediatePromise()	1.34 µs	1.28 µs	ℹ️ -4.64% faster (advisory)
C++ number property get/set	194.3 ns	200.1 ns	🟡 +2.99% slower (noisy)
C++ short ASCII string	193.8 ns	195.1 ns	🟡 +0.67% slower (noisy)
C++ Unicode string	430.8 ns	474.0 ns	🟡 +10.03% slower (noisy)
C++ nested Car struct	2.99 µs	3.04 µs	🟡 +1.53% slower (noisy)
C++ number | string variant	199.1 ns	189.3 ns	🟡 -4.95% faster (noisy)
Swift bounce(1 MiB)	471.9 ns	512.3 ns	🟡 +8.57% slower (noisy)
Swift copy(4 KiB)	1.78 µs	1.96 µs	🟡 +10.4% slower (noisy)
Swift large array (1,024)	63.82 µs	69.05 µs	🟡 +8.19% slower (noisy)
Swift small array (16)	1.28 µs	1.53 µs	🟡 +19.11% slower (noisy)
Swift synchronousCallback()	411.7 ns	438.7 ns	🟡 +6.57% slower (noisy)
Swift create()	46.90 µs	36.88 µs	🟡 -21.37% faster (noisy)
Swift returnExisting()	444.2 ns	412.3 ns	🟡 -7.17% faster (noisy)
Swift typed map (8 entries)	3.27 µs	3.37 µs	🟡 +3.25% slower (noisy)
Swift optional trailing string	253.0 ns	238.8 ns	🟡 -5.63% faster (noisy)
Swift addNumbers()	118.7 ns	133.2 ns	🟡 +12.25% slower (noisy)
Swift simpleFunc()	102.2 ns	102.3 ns	🟡 +0.11% slower (noisy)
Swift immediatePromise()	2.35 µs	2.26 µs	ℹ️ -4.07% faster (advisory)
Swift number property get/set	242.0 ns	259.6 ns	🟡 +7.28% slower (noisy)
Swift short ASCII string	258.2 ns	264.1 ns	🟡 +2.31% slower (noisy)
Swift Unicode string	560.3 ns	585.5 ns	🟡 +4.51% slower (noisy)
Swift nested Car struct	3.20 µs	3.17 µs	🟡 -0.9% faster (noisy)
Swift number | string variant	352.5 ns	353.2 ns	🟡 +0.19% slower (noisy)
TurboModule addNumbers()	1.36 µs	1.56 µs	🟡 +14.78% slower (noisy)

Android

Performance is unchanged! 😎

All Benchmarks

Benchmark	Before	After	Difference
JavaScript addNumbers()	31.4 ns	31.5 ns	⚪ ~0.31% unchanged
C++ bounce(1 MiB)	747.5 ns	752.1 ns	⚪ ~0.61% unchanged
C++ bounce(4 KiB)	748.2 ns	743.3 ns	🟡 -0.65% faster (noisy)
C++ copy(1 MiB)	46.20 µs	46.52 µs	⚪ ~0.69% unchanged
C++ copy(4 KiB)	1.49 µs	1.48 µs	⚪ ~0.7% unchanged
C++ large array (1,024)	57.75 µs	57.72 µs	⚪ ~0.05% unchanged
C++ small array (16)	1.27 µs	1.24 µs	⚪ ~1.99% unchanged
C++ synchronousCallback()	538.7 ns	537.9 ns	🟡 -0.15% faster (noisy)
C++ create()	989.8 ns	1.01 µs	⚪ ~2.33% unchanged
C++ returnExisting()	332.6 ns	332.5 ns	⚪ ~0.02% unchanged
C++ typed map (8 entries)	2.73 µs	2.75 µs	⚪ ~0.61% unchanged
C++ optional trailing string	230.8 ns	233.6 ns	⚪ ~1.21% unchanged
C++ addNumbers()	134.7 ns	133.4 ns	⚪ ~0.94% unchanged
C++ simpleFunc()	112.8 ns	112.8 ns	⚪ ~0.06% unchanged
C++ immediatePromise()	1.21 µs	1.20 µs	ℹ️ -0.98% faster (advisory)
C++ number property get/set	226.9 ns	229.1 ns	⚪ ~0.94% unchanged
C++ short ASCII string	215.0 ns	215.6 ns	⚪ ~0.27% unchanged
C++ Unicode string	424.3 ns	424.4 ns	⚪ ~0.05% unchanged
C++ nested Car struct	3.46 µs	3.44 µs	⚪ ~0.59% unchanged
C++ number | string variant	206.8 ns	207.9 ns	⚪ ~0.53% unchanged
Kotlin bounce(1 MiB)	1.88 µs	1.87 µs	🟡 -0.45% faster (noisy)
Kotlin bounce(4 KiB)	1.87 µs	1.88 µs	🟡 +0.36% slower (noisy)
Kotlin copy(1 MiB)	478.99 µs	477.90 µs	⚪ ~0.23% unchanged
Kotlin copy(4 KiB)	9.35 µs	9.18 µs	⚪ ~1.79% unchanged
Kotlin large array (1,024)	69.81 µs	70.42 µs	⚪ ~0.88% unchanged
Kotlin small array (16)	1.73 µs	1.75 µs	⚪ ~0.89% unchanged
Kotlin synchronousCallback()	1.78 µs	1.81 µs	🟡 +2.06% slower (noisy)
Kotlin create()	2.79 µs	2.73 µs	⚪ ~2.16% unchanged
Kotlin returnExisting()	953.1 ns	946.4 ns	⚪ ~0.7% unchanged
Kotlin typed map (8 entries)	12.02 µs	11.92 µs	⚪ ~0.79% unchanged
Kotlin optional trailing string	513.0 ns	509.0 ns	⚪ ~0.79% unchanged
Kotlin addNumbers()	185.1 ns	185.0 ns	⚪ ~0.03% unchanged
Kotlin simpleFunc()	155.2 ns	152.6 ns	⚪ ~1.69% unchanged
Kotlin immediatePromise()	3.66 µs	3.69 µs	ℹ️ +0.82% slower (advisory)
Kotlin number property get/set	369.6 ns	365.6 ns	⚪ ~1.09% unchanged
Kotlin short ASCII string	732.1 ns	731.4 ns	⚪ ~0.1% unchanged
Kotlin Unicode string	1.18 µs	1.17 µs	⚪ ~0.79% unchanged
Kotlin nested Car struct	8.39 µs	8.36 µs	⚪ ~0.3% unchanged
Kotlin number | string variant	658.4 ns	672.8 ns	⚪ ~2.18% unchanged
TurboModule addNumbers()	374.9 ns	372.7 ns	⚪ ~0.58% unchanged

Benchmarking Code Diff fe50d8fc...017e1b95 (view raw output)