fix(google): map Gemini finish_reason via enum value, not str()

[WatchTree-19]

problem

in the Gemini -> giskard translator (llm/translators/google_chat.py), the finish reason is looked up with str(candidate.finish_reason):

finish_reason = FINISH_REASON_MAP.get(str(candidate.finish_reason), "stop")

but candidate.finish_reason is a google.genai FinishReason enum, and str(FinishReason.MAX_TOKENS) is "FinishReason.MAX_TOKENS", not "MAX_TOKENS". FINISH_REASON_MAP is keyed on the bare names ("MAX_TOKENS", "SAFETY", ...), so every non-STOP reason misses the map and falls back to "stop". STOP only "works" by accident because the fallback is also "stop".

net effect: Gemini truncations are reported as normal completions (length lost) and, more importantly for a safety tool, SAFETY blocks / refusals are never surfaced as refusals.

repro (real google-genai SDK)

from google.genai.types import FinishReason
str(FinishReason.MAX_TOKENS)          # 'FinishReason.MAX_TOKENS'  (not 'MAX_TOKENS')
FINISH_REASON_MAP.get(str(FinishReason.MAX_TOKENS), "stop")  # 'stop'  -> should be 'length'

fix

look up via the enum's .value (getattr(finish_reason, "value", finish_reason), robust to both the real enum and the plain-string form used in dict-validated inputs). also fixed the refusal_out line so refusal text is a clean reason string rather than "FinishReason.SAFETY".

test

added test_from_google_max_tokens_maps_to_length and test_from_google_safety_maps_to_refusal mirroring the file's existing tests. before: 2 failed (assert 'stop' == 'length', assert 'stop' == 'refusal'); after: pass. the existing translator tests only covered STOP, which is indistinguishable from the fallback, so the bug went unnoticed. ruff clean.

found by reading the translator.

[gemini-code-assist]

Code Review

This pull request fixes an issue in the Google Chat translator where the candidate.finish_reason enum was not being correctly mapped because its string representation included the enum class name (e.g., FinishReason.SAFETY). The fix extracts the underlying string value using getattr before performing the lookup. Additionally, regression tests have been added to verify that finish reasons like MAX_TOKENS and SAFETY map correctly. I have no further feedback to provide.

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[kevinmessiaen]

Thanks for the fix @WatchTree-19