fix: Avoid mutating live network requests

[philprime]

📜 Description

Copy URLSessionTask.currentRequest before adding trace propagation headers and install the copied request through setCurrentRequest:. This prevents Sentry from mutating a request that CFNetwork may be reading concurrently.

Add regression coverage that verifies a mutable current request remains unchanged while the replacement request receives the trace headers.

💡 Motivation and Context

Network instrumentation previously mutated mutable currentRequest instances in place. Repeated or concurrent task resumes could race CFNetwork's access to the same request header storage and crash in CoreFoundation or CFNetwork.

The Swift network tracker conversion does not remove this path because header injection still delegates to SentryTracePropagation.

Fixes #8519

💚 How did you test it?

• make format
• make analyze
• make build-ios FOR_AGENTS=true
• make build-macos FOR_AGENTS=true
• make test-ios FOR_AGENTS=true ONLY_TESTING=SentryTests/SentryTracePropagationTests,SentryTests/SentryNetworkTrackerTests

The focused iOS run executed 100 tests with 0 failures. The equivalent macOS test command is currently blocked by unrelated test-target compilation errors in SentryOptionsDictionaryTests, SentrySpotlightTransportTests, and SentryTransportFactoryTests on the base branch.

📝 Checklist

You have to check all boxes before merging:

• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.
• Public API changes reviewed by another Mobile SDK team member or implemented according to the develop docs spec.
• If I added a new public API, I also added it to the SentryObjC wrapper.

[sentry]

📲 Install Builds

iOS

🔗 App Name	App ID	Version	Configuration
SDK-Size	io.sentry.sample.SDK-Size	9.25.0 (1)	Release

⚙️ sentry-cocoa Build Distribution Settings

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1235.51 ms	1264.82 ms	29.31 ms
Size	24.14 KiB	1.27 MiB	1.25 MiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
dcb456a	1220.98 ms	1246.74 ms	25.76 ms
952f116	1221.55 ms	1248.72 ms	27.17 ms
706c4c0	1213.06 ms	1252.94 ms	39.88 ms
b6b0d1d	1236.69 ms	1270.22 ms	33.52 ms
8693a8f	1222.37 ms	1249.31 ms	26.95 ms
52f26a1	1227.29 ms	1261.50 ms	34.21 ms
b6fa517	1218.83 ms	1257.47 ms	38.63 ms
7f28cd4	1215.77 ms	1242.98 ms	27.21 ms
5df460d	1230.49 ms	1260.69 ms	30.20 ms
f2e9a12	1223.86 ms	1264.56 ms	40.70 ms

App size

Revision	Plain	With Sentry	Diff
dcb456a	24.14 KiB	1.22 MiB	1.20 MiB
952f116	24.14 KiB	1.24 MiB	1.21 MiB
706c4c0	24.14 KiB	1.26 MiB	1.23 MiB
b6b0d1d	24.14 KiB	1.18 MiB	1.16 MiB
8693a8f	24.14 KiB	1.16 MiB	1.13 MiB
52f26a1	24.14 KiB	1.19 MiB	1.17 MiB
b6fa517	24.14 KiB	1.14 MiB	1.12 MiB
7f28cd4	24.14 KiB	1.23 MiB	1.21 MiB
5df460d	24.14 KiB	1.22 MiB	1.20 MiB
f2e9a12	24.14 KiB	1.27 MiB	1.25 MiB

Previous results on branch: philprime/network-instrumentation-8519

Startup times

Revision	Plain	With Sentry	Diff
7d22285	1211.29 ms	1255.36 ms	44.06 ms
65f5b6f	1206.22 ms	1244.58 ms	38.36 ms
be2121d	1233.62 ms	1265.92 ms	32.29 ms
dca42ff	1205.02 ms	1254.36 ms	49.34 ms

App size

Revision	Plain	With Sentry	Diff
7d22285	24.14 KiB	1.26 MiB	1.23 MiB
65f5b6f	24.14 KiB	1.27 MiB	1.25 MiB
be2121d	24.14 KiB	1.27 MiB	1.25 MiB
dca42ff	24.14 KiB	1.26 MiB	1.23 MiB

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[philipphofmann]

LGTM thanks