feat(attributes): Add gen_ai conversation compaction conventions

[cleptric]

Adds conventions for tracing GenAI conversation context compaction:

• gen_ai.compact span op and a new well-known gen_ai.operation.name value compact, for the operation that compacts a conversation's context (for example, summarizing earlier messages to fit the context window). Neither is in OpenTelemetry. The op also gets "Compaction" span name and description groups, and gen_ai.operation.type documents that compact spans map to other.
• gen_ai.conversation.compaction.reason (string, Sentry-specific) is set on the gen_ai.compact span and records what triggered it, for example manual, threshold or overflow.
• gen_ai.conversation.compacted (boolean, from the OpenTelemetry definition) is set on later requests that run on the compacted context. Instrumentations set it to true only when compaction was reliably applied and leave it unset otherwise, never false.

The resulting trace shape is a gen_ai.compact span with gen_ai.conversation.compaction.reason, its child gen_ai.chat span(s) for the model request that writes the summary, and later gen_ai.chat spans with gen_ai.conversation.compacted. Sentry's coding-agent tracing emits this shape.

Relay currently infers gen_ai.operation.type ai_client for unknown operation names, so it needs a follow-up to map compact to other.

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated
sentry-conventions	Ready	Preview	Oct 15, 2026 11:45am UTC

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Semver Impact of This PR

🟡 Minor (new features)

📋 Changelog Preview

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New Features ✨

Attributes

• Add gen_ai conversation compaction conventions by cleptric in #723

• Add http.request.duration by loewenheim in #697

Other

• (names) Add queue.publish/create/receive/process/settle to messaging span names by pabloDeputter in #705

Bug Fixes 🐛

• (attributes) Apply consistent scrubbing across deprecations by mjq in #692

Internal Changes 🔧

• (repo) Update CODEOWNERS to include @giortzisg by Lms24 in #708

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