fix(sdk): preserve partial assistant message on chat stream failure #8809

Job	Run time
Detect changes	7s
code-quality / code-quality	2m 17s
runops-guard / runops-guard	1m 56s
packages / 🧪 Unit Tests: Packages (3, 3)	4m 32s
packages / 🧪 Unit Tests: Packages (2, 3)	3m 12s
internal / 🧪 Unit Tests: Internal	6m 58s
e2e-webapp / 🧪 E2E Tests: Webapp	3m 48s
typecheck / typecheck	3m 33s
sdk-compat / Bun Runtime	2m 41s
sdk-compat / Deno Runtime	2m 20s
sdk-compat / Node.js 22.23 (warp-ubuntu-latest-x64-4x)	1m 30s
sdk-compat / Cloudflare Workers	2m 19s
packages / 🧪 Unit Tests: Packages (1, 3)	3m 17s
sdk-compat / Node.js 26.4 (warp-ubuntu-latest-x64-4x)	2m 21s
sdk-compat / Node.js 24.18 (warp-ubuntu-latest-x64-4x)	2m 16s
webapp / 🧪 Unit Tests: Webapp (9, 12)	7m 35s
sdk-compat / Node.js 20.20 (warp-ubuntu-latest-x64-4x)	1m 37s
webapp / 🧪 Unit Tests: Webapp (12, 12)	7m 2s
webapp / 🧪 Unit Tests: Webapp (7, 12)	7m 20s
webapp / 🧪 Unit Tests: Webapp (3, 12)	7m 30s
webapp / 🧪 Unit Tests: Webapp (4, 12)	7m 18s
webapp / 🧪 Unit Tests: Webapp (6, 12)	6m 58s
webapp / 🧪 Unit Tests: Webapp (2, 12)	6m 49s
webapp / 🧪 Unit Tests: Webapp (11, 12)	7m 34s
webapp / 🧪 Unit Tests: Webapp (8, 12)	7m 25s
webapp / 🧪 Unit Tests: Webapp (10, 12)	7m 6s
webapp / 🧪 Unit Tests: Webapp (5, 12)	7m 19s
webapp / 🧪 Unit Tests: Webapp (1, 12)	7m 4s
e2e	0s
packages / 📊 Merge Reports	16s
webapp / 📊 Merge Reports	17s
All PR Checks	4s
	2h 12m 21s

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