feat(observability): identify agent spans

[Ankcorn]

Why

Users need to compare Agent token usage, cost, model preferences, latency, and errors without stitching together different identity fields.

Closes #1975

What

Add a consistent identity block to SDK-created Agent spans:

• instrumentation_scope.name
• instrumentation_scope.version
• cloudflare.agents.session.id
• cloudflare.agents.session.name
• gen_ai.agent.name

---

[changeset-bot]

🦋 Changeset detected

Latest commit: 8d724ca

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
agents	Patch
@cloudflare/agent-think	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[devin-ai-integration]

Devin Review found 1 potential issue.

[devin-ai-integration]

🟡 Telemetry reports a frozen SDK version that no longer matches the actual release

The reported instrumentation version is written as a fixed string ("0.18.0" at packages/agents/src/observability/agent-span-attributes.ts:12) instead of being read from the package version, so it stops matching the real SDK version as soon as the package is bumped (this PR is already a version bump).
Impact: Anyone reading the traces sees a version label that is wrong, making it impossible to reliably tell which SDK version produced a span.

Version constant drifts from package.json on every release

The current packages/agents/package.json version is 0.18.0, matching the literal. However this PR ships a patch changeset (.changeset/curly-agents-trace.md), so the released version becomes 0.18.1 while instrumentation_scope.version stays 0.18.0. There is no build-time injection (scripts/build.ts performs no version substitution) and the accompanying test (packages/agents/src/tests/observability/agent-span-attributes.test.ts:14) hardcodes the same literal, so it cannot detect drift against package.json. Every future release requires a manual edit here or the emitted scope version silently diverges from the true SDK version.

Prompt for agents

The instrumentation_scope.version in packages/agents/src/observability/agent-span-attributes.ts is hardcoded to "0.18.0" and will drift from the real package version on every release (this PR itself is a patch bump to 0.18.x). There is no build-time version injection in packages/agents/scripts/build.ts. Consider deriving the version from packages/agents/package.json (e.g. an import of the version, or a build-time define/replace injected into the bundle) so the emitted instrumentation_scope.version always matches the shipped SDK version. Update the test in packages/agents/src/tests/observability/agent-span-attributes.test.ts accordingly so it validates against the single source of truth rather than duplicating the literal.

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[mattzcarey]

can we remove this. froxen versions are not gonna be fun

[pkg-pr-new]

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agents

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@cloudflare/ai-chat

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@cloudflare/codemode

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create-think

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hono-agents

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@cloudflare/shell

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@cloudflare/think

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@cloudflare/voice

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@cloudflare/worker-bundler

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commit: 8d724ca