Photon's Node sidecar intentionally hides raw handler exceptions, but the Python adapter still needs a safe failure class and retryability bit so delivery retries do not collapse into an opaque generic 500.
Constraint: Sidecar responses must not leak raw stack traces or private exception text
Rejected: Retry every internal sidecar error | masks permanent auth/config failures
Confidence: high
Scope-risk: narrow
Directive: Keep sidecar error text generic; extend safe error classes instead of exposing raw SDK failures
Tested: uv run --with pytest-timeout pytest tests/plugins/platforms/photon/test_overflow_recovery.py -q
Tested: uv run --with pytest-timeout pytest tests/plugins/platforms/photon -q
Tested: uv run ruff check plugins/platforms/photon/adapter.py tests/plugins/platforms/photon/test_overflow_recovery.py
Tested: python3 -m py_compile plugins/platforms/photon/adapter.py tests/plugins/platforms/photon/test_overflow_recovery.py
Tested: node --check plugins/platforms/photon/sidecar/index.mjs
Tested: git diff --check
Tested: python3 scripts/check-windows-footguns.py --diff origin/main
Not-tested: Live Photon/Spectrum delivery against a real iMessage account
Related: #50971
91c4c6f9d2