[alexander-alderman-webb]

Description

Issues

Reminders

• Please add tests to validate your changes, and lint your code using uv run ruff.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[sentry-warden]

Singleton AI response lists are now emitted as JSON arrays

set_data_normalized() now preserves list values, then JSON-serializes them as arrays. Several integrations pass text outputs as lists even when there is only one text block, so a span that previously exposed "Hi, I'm Claude." now exposes ["Hi, I'm Claude."]. This changes the shape of the emitted span attribute and conflicts with existing tests and consumers expecting a scalar. Flatten scalar-semantic outputs at those call sites, or update the tests and document the new attribute shape if this is intentional.

Evidence

• _normalize_data() preserves lists, and set_data_normalized() JSON-serializes non-scalars; a one-item list therefore remains a JSON array string.
• anthropic._set_output_data() collects text blocks in output_messages["response"] and passes that list to set_data_normalized().
• The Anthropic tests still assert a bare "Hi, I'm Claude." value for these responses, confirming the emitted shape no longer matches the existing expectation.
• LangChain also passes nested generation text lists to set_data_normalized(), so singleton generation results are affected as well.

_{Identified by Warden · code-review · 8XB-P9Q}