feat(observability): route eval scores through ScoreEvent bus

[intojhanurag]

Description

Wires Mastra eval scores through the unified observability bus so every exporter implementing onScoreEvent automatically receives them. Replaces the deprecated per-exporter addScoreToTrace side-channel that bypassed the pipeline. Also unblocks Mastra spans appearing under Braintrust experiment eval spans (#11097) as a side effect of the unified path.

• Producer alignment: packages/core/src/mastra/hooks.ts no longer iterates exporters with addScoreToTrace. MastraScorer.run() (already on main from PR Add scorer tracing and export scores through the observability bus #14920) remains the single producer of ScoreEvents through mastra.observability.addScore().
• Consumer side: implemented onScoreEvent on Langfuse (LangfuseClient.score.create), Laminar (/v1/evaluators/score), Braintrust (logger.logFeedback), Datadog (tracer.llmobs.submitEvaluation), and LangSmith (Client.createFeedback).
• Backwards compatibility: Langfuse addScoreToTrace and Laminar _addScoreToTrace are preserved as @deprecated wrappers that forward to a shared private submitScore helper.
• Bug fix in observability/mastra/src/recorded.ts: buildScoreEvent now forwards scorerName and targetEntityType from ScoreInput to ExportedScore (without this, exporters silently fell back to scorerId).
• Tests: rewrote core hook test to assert the hook no longer publishes a ScoreEvent; added per-exporter onScoreEvent tests; added a regression test for buildScoreEvent field forwarding.
• Seven single-package changesets created (@mastra/core, @mastra/observability, @mastra/langfuse, @mastra/laminar, @mastra/braintrust, @mastra/datadog, @mastra/langsmith) per the project's changeset style guide.

Related Issue(s)

Fixes #10896 (also unblocks #11097)

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Code refactoring
• Performance improvement
• Test update

Checklist

• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works
• I have addressed all Coderabbit comments on this PR

ELI5

When Mastra assigns an evaluation score, this PR sends that score exactly once into a single observability "bus" so all monitoring/exporter integrations (Langfuse, Laminar, Braintrust, Datadog, LangSmith, etc.) automatically receive it — avoiding exporter-specific wiring and duplicate deliveries.

Overview

Routes Mastra evaluation scores through the unified observability ScoreEvent bus (mastra.observability.addScore) so any exporter implementing onScoreEvent receives them. MastraScorer.run() remains the single producer of ScoreEvent; the core scorer hook no longer iterates exporters to call addScoreToTrace. Per-exporter addScoreToTrace/_addScoreToTrace behaviors are preserved as @deprecated wrappers that forward to shared submit helpers where applicable. Fixes a bug in buildScoreEvent so scorerName and targetEntityType from ScoreInput are forwarded into emitted ExportedScore.

Changes by Component

Core (@mastra/core)

• Removed exporter-iteration and addScoreToTrace republishing from createOnScorerHook; the hook now only persists scores to the legacy scores store.
• Ensures MastraScorer.run() is the single producer of ScoreEvent.
• Registers static workflow-step scorers synchronously during addWorkflow and resolves dynamic scorers asynchronously so scorers are registered before use.
• Updated core test to assert the hook does not emit ScoreEvent.

Observability (@mastra/observability)

• Fix: buildScoreEvent (observability/mastra/src/recorded.ts) now includes scorerName and targetEntityType in emitted ScoreEvent.
• Bus routing: route-event now prefers onScoreEvent; if an exporter lacks onScoreEvent but implements deprecated addScoreToTrace, the bus maps the ScoreEvent into the legacy addScoreToTrace payload and calls it (avoids duplicate delivery when both exist).
• Added unit tests for score routing behavior and the buildScoreEvent regression.

Exporter Integrations (new onScoreEvent handlers + tests)

• Langfuse (@mastra/langfuse)

  • Added onScoreEvent → LangfuseClient.score.create with a shared submitScore helper and centralized error logging.
  • Preserved addScoreToTrace as a deprecated wrapper forwarding to submitScore.
  • Tests updated to cover onScoreEvent and mark addScoreToTrace deprecated.

• Laminar (@mastra/laminar)

  • Added onScoreEvent delegating to a private submitScore that POSTS to /v1/evaluators/score.
  • submitScore converts trace/span IDs to Laminar/OTel UUIDs, merges metadata/reason, enforces timeouts via AbortController, and logs non-OK/timed-out responses.
  • Preserved _addScoreToTrace as a @deprecated wrapper forwarding to submitScore.
  • Tests verify POST payload mapping and wrapper behavior.

• Braintrust (@mastra/braintrust)

  • Added onScoreEvent that calls logger.logFeedback using spanId (falling back to traceId) and skips when neither is present.
  • Maps scorer name/ID, reason, and metadata into the feedback payload and logs failures.
  • Tests cover span/trace fallback and skip behavior.

• Datadog (@mastra/datadog)

  • Added onScoreEvent: validates traceId/spanId, looks up exported dd-trace span context (traceState), and calls tracer.llmobs.submitEvaluation with mapped fields (label/value/metricType/mlApp/timestamp/reason/metadata).
  • Drops scores when identifiers or exported span context are missing and warns when scores arrive before the span is exported.
  • Tests cover successful submission, unknown IDs (no-op), and dropping out-of-order scores.

• LangSmith (@mastra/langsmith)

  • Added onScoreEvent that submits Client.createFeedback when a spanId→LangSmith runId mapping exists.
  • Introduced a configurable bounded LRU spanId→runId cache (runIdCacheMaxEntries) populated from RunTree building; evicts oldest entries when full and is cleared on shutdown.
  • Ensures authoritative scorerId/scoreSource are preserved in sourceInfo and ignores events when span/run mapping is absent.
  • Tests cover mapping semantics, eviction, metadata protection, and skipping unseen spans.

Tests

• Core hook test rewritten to assert the hook does not publish ScoreEvent.
• Per-exporter onScoreEvent test suites added for Langfuse, Laminar, Braintrust, Datadog, and LangSmith covering field mapping, identifier fallbacks, ordering/dropping, timeout handling, and cache eviction.
• Bus tests added to assert onScoreEvent preferred and legacy addScoreToTrace fallback behavior.
• Regression test added to ensure buildScoreEvent forwards scorerName and targetEntityType.

Backwards Compatibility

• Deprecated addScoreToTrace/_addScoreToTrace preserved (where present) as wrappers that forward to the new onScoreEvent/submit helpers to avoid breaking existing callers.
• Observability interface docs updated to deprecate addScoreToTrace in favor of onScoreEvent/ScoreEvent bus.
• No breaking public API surface changes beyond documented additions and deprecations.

Commits & Release Notes

• Seven package-scoped changesets created for @mastra/core, @mastra/observability, @mastra/langfuse, @mastra/laminar, @mastra/langsmith, @mastra/datadog, and @mastra/braintrust documenting onScoreEvent support and the buildScoreEvent fix.
• Exporter-specific notes documented (Datadog ordering caveat; Laminar timeout/error logging; LangSmith runId cache behavior).

Related Issues

Fixes #10896 and unblocks #11097.

[vercel]

@intojhanurag is attempting to deploy a commit to the Mastra Team on Vercel.

A member of the Team first needs to authorize it.

[changeset-bot]

🦋 Changeset detected

Latest commit: 2503c14

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

This PR includes changesets to release 35 packages

Name	Type
@mastra/langfuse	Minor
@mastra/core	Minor
@mastra/langsmith	Minor
@mastra/laminar	Minor
@mastra/observability	Patch
@mastra/braintrust	Minor
@mastra/datadog	Minor
mastracode	Patch
@mastra/mcp-docs-server	Patch
@internal/playground	Patch
@mastra/client-js	Patch
@mastra/opencode	Patch
@mastra/longmemeval	Patch
@mastra/express	Patch
@mastra/fastify	Patch
@mastra/hono	Patch
@mastra/koa	Patch
@mastra/nestjs	Patch
@mastra/otel-bridge	Patch
@mastra/otel-exporter	Patch
@mastra/posthog	Patch
@mastra/sentry	Patch
mastra	Patch
@mastra/deployer-cloud	Minor
@mastra/deployer-vercel	Patch
@mastra/playground-ui	Patch
@mastra/react	Patch
@mastra/arize	Patch
@mastra/arthur	Patch
@mastra/server	Minor
@mastra/deployer	Minor
create-mastra	Patch
@mastra/deployer-cloudflare	Patch
@mastra/deployer-netlify	Patch
@mastra/temporal	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

[coderabbitai]

Note

Reviews paused

It looks like this branch is under active development. To avoid overwhelming you with review comments due to an influx of new commits, CodeRabbit has automatically paused this review. You can configure this behavior by changing the reviews.auto_review.auto_pause_after_reviewed_commits setting.

Use the following commands to manage reviews:

• @coderabbitai resume to resume automatic reviews.
• @coderabbitai review to trigger a single review.

Use the checkboxes below for quick actions:

• ▶️ Resume reviews
• 🔍 Trigger review

Walkthrough

Centralizes evaluator score emission onto a ScoreEvent bus: scorer runs call mastra.observability.addScore(), buildScoreEvent now includes scorerName and targetEntityType, hooks no longer republish scores to exporters, and exporters implement new onScoreEvent handlers while preserving deprecated addScoreToTrace/_addScoreToTrace wrappers.

Changes

Unified Score Event Pipeline

Layer / File(s)	Summary
Data Shape observability/mastra/src/recorded.ts, observability/mastra/src/tracing.test.ts, packages/core/src/storage/domains/observability/record-builders.ts, .../record-builders.test.ts	buildScoreEvent now forwards scorerName and targetEntityType; persisted score records gain top-level scorerName (removed from metadata); tests updated.
Core hook & registration packages/core/src/mastra/hooks.ts, packages/core/src/mastra/hook.test.ts, packages/core/src/mastra/index.ts, packages/core/src/mastra/scorer-registration.test.ts, packages/core/src/workflows/handlers/step.ts	Removed legacy exporter republishing from scorer hook; hook now only saves to legacy scores store. Workflow registration synchronously registers static step scorers and asynchronously lists dynamic scorers; scorer execution registers scorers with engine.mastra; tests added for registration timing and hook behavior.
Score record shape / storage packages/core/src/storage/domains/observability/record-builders.ts, .../record-builders.test.ts	Score records now include top-level `scorerName: string
Bus routing / backward-compat observability/mastra/src/bus/route-event.ts, observability/mastra/src/bus/observability-bus.test.ts	ScoreEvent routing prefers onScoreEvent; when absent, routes to legacy addScoreToTrace with mapped fields; tests cover precedence and fallback.
LangSmith exporter observability/langsmith/src/tracing.ts, observability/langsmith/src/tracing.test.ts	Added bounded LRU spanId → langSmith runId cache with config runIdCacheMaxEntries; populate on RunTree build; implement onScoreEvent to createFeedback when mapping exists; clear cache on shutdown; tests for happy path, missing spans, and cache eviction.
Langfuse exporter observability/langfuse/src/tracing.ts, observability/langfuse/src/tracing.test.ts	Added private submitScore() and public onScoreEvent(event: ScoreEvent) delegating to it; refactored addScoreToTrace to call submitScore (deprecated wrapper); tests renamed/added for deprecated and new behavior.
Laminar exporter observability/laminar/src/tracing.ts, observability/laminar/src/tracing.test.ts	Introduced submitScore() helper (builds payload, converts IDs, enforces timeout, logs non-OK/errors); added onScoreEvent delegating to it; replaced _addScoreToTrace with deprecated wrapper; tests validate HTTP payload and UUID conversion.
Datadog exporter observability/datadog/src/tracing.ts, observability/datadog/src/tracing.test.ts	Added onScoreEvent(event: ScoreEvent) that validates traceId/spanId, looks up exported dd-trace context, and uses tracer.llmobs.submitEvaluation with mapped options; tests cover exported-span lookup, unknown spans, and early-event dropping.
Braintrust exporter observability/braintrust/src/tracing.ts, observability/braintrust/src/tracing.test.ts	Added onScoreEvent(event: ScoreEvent) to call logger.logFeedback using spanId or traceId as id; skips when identifiers are missing; tests cover id selection and no-op behavior.
Changesets / releases & docs .changeset/*, docs/src/content/en/reference/observability/tracing/interfaces.mdx	Added/updated changeset entries documenting minor/patch releases across @mastra/* packages describing the new onScoreEvent integrations and the buildScoreEvent fix; docs annotated addScoreToTrace as deprecated.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~55 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 40.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title clearly describes the main change: routing eval scores through the ScoreEvent bus. It is concise, specific, and uses imperative mood with proper capitalization.
Linked Issues check	✅ Passed	The PR fully addresses issue #10896 by implementing eval scoring support across all exporters through the unified observability pipeline via ScoreEvent bus and onScoreEvent handlers.
Out of Scope Changes check	✅ Passed	All changes are directly related to implementing eval score routing: exporter onScoreEvent implementations, ScoreEvent bus routing, deprecated addScoreToTrace wrappers, scorer registration for workflows, and supporting infrastructure. No unrelated changes detected.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Tip

💬 Introducing Slack Agent: The best way for teams to turn conversations into code.

Slack Agent is built on CodeRabbit's deep understanding of your code, so your team can collaborate across the entire SDLC without losing context.

• Generate code and open pull requests
• Plan features and break down work
• Investigate incidents and troubleshoot customer tickets together
• Automate recurring tasks and respond to alerts with triggers
• Summarize progress and report instantly

Built for teams:

• Shared memory across your entire org—no repeating context
• Per-thread sandboxes to safely plan and execute work
• Governance built-in—scoped access, auditability, and budget controls

One agent for your entire SDLC. Right inside Slack.

👉 Get started

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Actionable comments posted: 6

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In @.changeset/five-stars-smile.md:
- Around line 5-38: The changeset text currently includes exporter-side
migration details (mentions of onScoreEvent, addScoreToTrace deprecation, and
usage examples) that apply beyond `@mastra/core`; edit the
.changeset/five-stars-smile.md content so it only describes the core change
(MastraScorer.run() now producing score events via
mastra.observability.addScore() and that ScoreEvent is the unified pipeline) and
remove exporter migration examples and deprecation notes (onScoreEvent,
addScoreToTrace usage) from this file; if you want to keep exporter migration
guidance, create separate changeset(s) in the exporter package(s) with those
details and ensure the frontmatter only lists `@mastra/core`.

In @.changeset/giant-apes-accept.md:
- Line 5: Rewrite the changeset line to state the user-facing outcome instead of
implementation details: replace the sentence that mentions onScoreEvent,
mastra.observability.addScore(), and Client.createFeedback with a short
description of what `@mastra/langsmith` users will experience (e.g., "Evaluation
scores are automatically submitted to LangSmith and associated with the
corresponding run for easier tracking and review"), keeping the focus on the
product behavior and benefit rather than the internal function names.

In @.changeset/ready-socks-leave.md:
- Line 5: Edit the changeset description so it only refers to the package listed
in the frontmatter (`@mastra/observability`): remove or reword any mentions of
other exporter packages (Langfuse, Braintrust, LangSmith, Laminar) and the
broader behavior implications, and instead state the scoped change (forwarding
scorerName and targetEntityType onto ExportedScore) as applying solely to
`@mastra/observability`; keep the technical detail but restrict the impact
language to that single package.

In `@observability/datadog/src/tracing.test.ts`:
- Around line 1575-1620: The test suite is missing a case where a score arrives
before SPAN_ENDED and currently onScoreEvent drops such scores because it checks
this.traceState.get(score.traceId)?.contexts.get(score.spanId) and returns if
not exported; add a unit test that calls exporter.onScoreEvent(...) with a score
for an active span before emitting a SPAN_ENDED (use
createMockSpan/createTracingEvent to create the span), assert the current
behavior fails, then choose one remediation: either implement buffering inside
onScoreEvent (store pending scores keyed by traceId/spanId and flush them when
the SPAN_ENDED path sets exported in traceState) or add a clear comment and
runtime warning in the exporter code documenting that scores must only be sent
after SPAN_ENDED (update onScoreEvent to log/throw when a score is received for
an unexported span); update tests to reflect the chosen behavior.

In `@observability/laminar/src/tracing.ts`:
- Around line 392-396: The POST to /v1/evaluators/score should use an
AbortSignal with the existing timeoutMillis to avoid hanging; update the code
around the fetch call in tracing.ts (where score is submitted) to create an
AbortController, pass controller.signal into fetch options, start a setTimeout
that calls controller.abort() after timeoutMillis (or
this.config.timeoutMillis), and clear the timer once fetch resolves or throws so
you don't leak timers; ensure any AbortError is handled/propagated consistently
by the surrounding function (e.g., the score submission method).

In `@observability/langsmith/src/tracing.test.ts`:
- Around line 1410-1451: The test reveals feedback uses Mastra span/trace IDs
that LangSmith doesn't know about; update buildRunTreePayload and span creation
so LangSmith run IDs are preserved or recorded, and make onScoreEvent look up
the LangSmith runId before calling client.createFeedback. Specifically, either
include span.id as the id field when instantiating new RunTree (and when calling
createChild) so LangSmith uses the Mastra span.id as its runId, or modify the
span creation flow to capture and store the LangSmith-allocated runId into
traceData (e.g., traceData[traceId].runId or traceData.spanRunIds[spanId]) and
then change onScoreEvent to read that stored LangSmith runId (instead of using
spanId/traceId directly) before invoking mockClient.createFeedback /
client.createFeedback.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 43c69fbf-759b-4c7e-87cf-87b800c6ca89

📥 Commits

Reviewing files that changed from the base of the PR and between 7679a63 and f6f07f4.

📒 Files selected for processing (21)

• .changeset/dark-rooms-build.md
• .changeset/five-stars-smile.md
• .changeset/giant-apes-accept.md
• .changeset/large-yaks-battle.md
• .changeset/ready-socks-leave.md
• .changeset/tiny-doodles-hang.md
• .changeset/violet-rules-design.md
• observability/braintrust/src/tracing.test.ts
• observability/braintrust/src/tracing.ts
• observability/datadog/src/tracing.test.ts
• observability/datadog/src/tracing.ts
• observability/laminar/src/tracing.test.ts
• observability/laminar/src/tracing.ts
• observability/langfuse/src/tracing.test.ts
• observability/langfuse/src/tracing.ts
• observability/langsmith/src/tracing.test.ts
• observability/langsmith/src/tracing.ts
• observability/mastra/src/recorded.ts
• observability/mastra/src/tracing.test.ts
• packages/core/src/mastra/hook.test.ts
• packages/core/src/mastra/hooks.ts

[coderabbitai]

Actionable comments posted: 3

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In @.changeset/five-stars-smile.md:
- Around line 5-7: Rewrite the changeset entry to lead with the user-facing
outcome: explain that scores are now emitted once via the unified observability
pipeline (mastra.observability.addScore()) and therefore exporters no longer
receive duplicate deliveries; remove implementation-focused references to
createOnScorerHook and the exporter iteration, but keep a short parenthetical
note that MastraScorer.run() is the single source of score events if extra
clarity is needed.

In `@observability/langsmith/src/tracing.ts`:
- Line 74: The private Map field `#langsmithRunIdBySpanId` (and the other similar
maps referenced) is unbounded and can cause memory leaks; replace it with a
bounded cache (e.g., an LRU or size-limited Map with eviction) or add TTL
eviction to cap growth, and update all usages (put/get/delete in the methods
that reference `#langsmithRunIdBySpanId` and the other two maps mentioned) to use
the new cache API so entries are evicted automatically when the capacity/age
limit is reached; ensure construction of the cache is configurable (max size /
TTL) so tests or shutdown logic can still clear it explicitly.
- Around line 142-146: The sourceInfo construction currently spreads
score.metadata last which allows metadata to overwrite reserved fields; in
tracing.ts change the order or sanitize metadata so reserved keys remain
authoritative — either spread ...(score.metadata ?? {}) first and then add
scorerId: score.scorerId and ...(score.scoreSource ? { scoreSource:
score.scoreSource } : {}), or prefilter score.metadata to remove "scorerId" and
"scoreSource" before spreading; update the sourceInfo creation to use one of
these approaches so scorerId and scoreSource in sourceInfo cannot be
overwritten.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: bc1f59ce-f282-4965-aaf6-4ed680440413

📥 Commits

Reviewing files that changed from the base of the PR and between f6f07f4 and 7d3db72.

📒 Files selected for processing (8)

• .changeset/five-stars-smile.md
• .changeset/giant-apes-accept.md
• .changeset/ready-socks-leave.md
• observability/datadog/src/tracing.test.ts
• observability/datadog/src/tracing.ts
• observability/laminar/src/tracing.ts
• observability/langsmith/src/tracing.test.ts
• observability/langsmith/src/tracing.ts

✅ Files skipped from review due to trivial changes (3)

• .changeset/giant-apes-accept.md
• observability/datadog/src/tracing.test.ts
• observability/langsmith/src/tracing.test.ts

🚧 Files skipped from review as they are similar to previous changes (2)

• .changeset/ready-socks-leave.md
• observability/laminar/src/tracing.ts

[coderabbitai]

🧹 Nitpick comments (1)

observability/mastra/src/bus/observability-bus.test.ts (1)

265-281: ⚡ Quick win

Strengthen fallback payload coverage with explicit non-default fields.

This test validates fallback dispatch, but it currently uses default score fixtures where scorerName, spanId, and metadata are unset. Setting them explicitly here would better protect against mapping regressions.

Proposed test hardening

-      const event = createScoreEvent();
+      const event: ScoreEvent = {
+        type: 'score',
+        score: {
+          ...createScoreEvent().score,
+          spanId: 'span-legacy-1',
+          scorerName: 'relevance-v2',
+          metadata: { source: 'eval-suite' },
+        },
+      };
       bus.emit(event);

       expect(addScoreToTrace).toHaveBeenCalledWith({
         traceId: event.score.traceId,
         spanId: event.score.spanId,
         score: event.score.score,
         reason: event.score.reason,
         scorerName: event.score.scorerName ?? event.score.scorerId,
         metadata: event.score.metadata,
       });

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@observability/mastra/src/bus/observability-bus.test.ts` around lines 265 -
281, The test "should fall back to deprecated addScoreToTrace for exporters
without onScoreEvent" uses default fixture values so update the created event
from createScoreEvent() to set explicit non-default fields (e.g., provide a
concrete scorerName, a non-empty spanId, and non-empty metadata) before calling
bus.emit(event); then assert addScoreToTrace was called with the mapped payload
containing those explicit values (ensure the scorerName vs scorerId selection
logic is exercised) so the fallback mapping in
createMockExporter/addScoreToTrace is robustly covered.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@observability/mastra/src/bus/observability-bus.test.ts`:
- Around line 265-281: The test "should fall back to deprecated addScoreToTrace
for exporters without onScoreEvent" uses default fixture values so update the
created event from createScoreEvent() to set explicit non-default fields (e.g.,
provide a concrete scorerName, a non-empty spanId, and non-empty metadata)
before calling bus.emit(event); then assert addScoreToTrace was called with the
mapped payload containing those explicit values (ensure the scorerName vs
scorerId selection logic is exercised) so the fallback mapping in
createMockExporter/addScoreToTrace is robustly covered.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: c13bcff5-6a1b-4d96-b2e4-bf73b286b8c5

📥 Commits

Reviewing files that changed from the base of the PR and between b62e978 and 1183a1f.

📒 Files selected for processing (6)

• .changeset/ready-socks-leave.md
• observability/mastra/src/bus/observability-bus.test.ts
• observability/mastra/src/bus/route-event.ts
• packages/core/src/mastra/index.ts
• packages/core/src/mastra/scorer-registration.test.ts
• packages/core/src/workflows/handlers/step.ts

🚧 Files skipped from review as they are similar to previous changes (2)

• .changeset/ready-socks-leave.md
• packages/core/src/mastra/index.ts