fix: preserve live resumption transparency

[he-yufeng]

Summary

• stop forcing session_resumption.transparent = True when run_live() reconnects with a saved handle
• keep the caller's original SessionResumptionConfig.transparent value intact
• add a regression test for the default basic session-resumption path

Why

Gemini Developer API supports live session resumption, but not transparent session resumption. The reconnect path was mutating the config from a basic resumption request into transparent resumption, which makes Gemini reject the reconnect.

To verify

• uv run pytest tests/unittests/flows/llm_flows/test_base_llm_flow.py -q
• uv run pyink --check src/google/adk/flows/llm_flows/base_llm_flow.py tests/unittests/flows/llm_flows/test_base_llm_flow.py
• git diff --check

Fixes #5771

[he-yufeng]

Rebased this onto current main and reran the focused checks.

Validation:

PYTHONUTF8=1 .\.venv\Scripts\python.exe -m pytest tests\unittests\flows\llm_flows\test_base_llm_flow.py -q --basetemp .tmp\pytest-5784-rebase
# 31 passed, 1 warning

PYTHONUTF8=1 .\.venv\Scripts\python.exe -m pyink src\google\adk\flows\llm_flows\base_llm_flow.py tests\unittests\flows\llm_flows\test_base_llm_flow.py --check
PYTHONUTF8=1 .\.venv\Scripts\python.exe -m py_compile src\google\adk\flows\llm_flows\base_llm_flow.py tests\unittests\flows\llm_flows\test_base_llm_flow.py
git diff --check upstream/main..HEAD

[he-yufeng]

Rebased onto current main again; no code changes beyond the rebase.\n\nValidation on Windows:\n- uv run --no-sync pytest tests\unittests\flows\llm_flows\test_base_llm_flow.py -q --basetemp .tmp\pytest-5784-20260524 -p no:cacheprovider -> 31 passed, 1 existing experimental warning\n- uv run --no-sync pyink --check src\google\adk\flows\llm_flows\base_llm_flow.py tests\unittests\flows\llm_flows\test_base_llm_flow.py\n- uv run --no-sync python -m py_compile src\google\adk\flows\llm_flows\base_llm_flow.py tests\unittests\flows\llm_flows\test_base_llm_flow.py\n- git diff --check upstream/main..HEAD

[he-yufeng]

Rebased onto current upstream/main. Current head is 1e2e450.

Validation on Windows after rebase:

• uv run --no-sync pytest tests\unittests\flows\llm_flows\test_base_llm_flow.py -q --basetemp .tmp\pytest-5784-20260527 -p no:cacheprovider -> 31 passed, 1 warning
• uv run --no-sync python -m py_compile src\google\adk\flows\llm_flows\base_llm_flow.py tests\unittests\flows\llm_flows\test_base_llm_flow.py
• uv run --no-sync pyink --check src\google\adk\flows\llm_flows\base_llm_flow.py tests\unittests\flows\llm_flows\test_base_llm_flow.py
• git diff --check upstream/main...HEAD

The warning is the existing experimental JSON_SCHEMA_FOR_FUNC_DECL warning from this test file.

[rohityan]

Hi @he-yufeng , Thank you for your contribution! We appreciate you taking the time to submit this pull request. Your PR has been received by the team and is currently under review. We will provide feedback as soon as we have an update to share.

[rohityan]

Hi @wyf7107 , please review this.