feat(libsy): record task_kind and agent_role on the run span

[yanyanz89]

What

run_span records session_id, agent_id, task_id, and correlation_id from the request Metadata, but not task_kind or agent_role. This adds them.

Why

Metadata::from_headers already parses both on every request, and they are the only fields describing what kind of work a request is; everything else is an opaque id. Today they are parsed and then dropped before reaching telemetry, so routing behaviour cannot be segmented by work type. #145 noted the same gap on live traffic and left it as a follow-up.

Both have real producers: Codex emits them inside x-codex-turn-metadata, and HEADER_CONFIG already normalizes them.

Span fields only. No metric gains a label, so the bounded-label invariant in docs/internal/metrics_reference.md is unaffected.

Related: #145

How tested

Rust-only change, so the Python gates do not apply.

• cargo fmt --all -- --check clean
• cargo clippy -p switchyard-libsy --all-targets -- -D warnings clean
• cargo test -p switchyard-libsy --test observability green (6 passed)

Extends the existing span assertions in successful_run_records_metrics_spans_and_decision_log. Stashing only the src change while keeping the test fails with left: None, right: Some("code_review"), so the coverage is load-bearing rather than incidentally green.

Checklist

• One class per file; filename = snake_case of the primary class. — N/A
• New public symbols exported from switchyard/__init__.py.__all__ if intended for downstream use. — N/A
• Unit tests added for new components / bug fixes.
• README / --help updated if customer-facing surface changed. — N/A
• Commits signed off (Signed-off-by: Your Name <email>) per the DCO.

Notes for reviewers

• Naming follows the bare-name siblings in the same array rather than the namespaced forms also present on this span. Happy to use an OpenTelemetry semantic-convention name instead.
• agent_kind left out to keep this to one concern.
• Touches the same file as feat(observability): add GenAI semantic attributes #224 and is meant to complement it; happy to rebase or defer.

Summary by CodeRabbit

• New Features
  • Run telemetry now records task type and agent role when available.
  • These fields are included in run spans, improving observability and filtering.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 6a8e0492-9fa7-44ce-8a0b-c6f2bc7f5cdd

📥 Commits

Reviewing files that changed from the base of the PR and between 3acf3d8 and 3278162.

📒 Files selected for processing (2)

• crates/libsy/src/observability.rs
• crates/libsy/tests/observability.rs

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Walkthrough

The change adds task_kind and agent_role fields to libsy.run spans. Request metadata populates these fields when available. Tests verify the recorded values.

Changes

Observability metadata

Layer / File(s)	Summary
Record and verify run metadata crates/libsy/src/observability.rs, crates/libsy/tests/observability.rs	libsy.run spans now include task_kind and agent_role. Request metadata populates both fields, and tests verify the values.
Estimated code review effort: 1 (Trivial)	~5 minutes

Poem

A rabbit hops through traced-out code,
Two labels join the span’s light load.
“code_review” and “reviewer” appear,
Tests confirm their meaning clear.
Hop, hop—metadata is here!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: recording task_kind and agent_role on the run span.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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